I've been here for a while but never posted anything.
I love this place.

Simple Full Complementary Simetry +/-80V. Voltage amplifier/driver biased with 30mA. This driver circuit stabilized BIAS in output stage. Exelent stability without oscilation, hum and noise, sound great.
RMS Power: 240W 8ohm, 350W 4ohm

Go to post #470 for schematic and PCB
http://www.diyaudio.com/forums/solid-state/162043-mosfet-amplifier-irfp240-irfp9240-47.html

Hello all I'm new to diyAudio - My main interests vacuum tube amplifiers and transmission line speakers

Illustrated build guide for the BA-3 amplifier (With complimentary output stage)

The “Burning Amplifier” series is a selection of modular amplifier pieces designed by our technical, spiritual, and menu advisor, Nelson Pass. The pieces can be mixed and matched, used with a range of PSU voltages and scaled up or down as you desire. (The limit, as always with class-A amplifiers being how much heatsink you have…)

There are two gain stages or ‘front-ends’, The BA-1&2 gain stage is a differential pair voltage amplifier with CCS, using some feedback. It can accept a single ended or balanced input. The BA-3 gain stage is a complimentary pair voltage amp with no feedback. There is no ‘better’ between the two stages, just different. You are encouraged to try both and report back your findings.

This guide uses this PCB - P-BAGSN-1V20 - Burning Amplifier Gain Stage for BA-3 (Requires bias boards and output stage; Makes 2 channels; Rev 2.0) - Circuit Boards


The output stages are Complimentary (Push-Pull) and Single-ended. Both these stages can be scaled to hold as many pairs of output Mosfet as you desire, the PCB have provisions for daisy-chain links to add as many boards as you like. (Heatsink and physical area of your case being the limit.)
The Complimentary output (push-pull) is identical to the F4, without the F4’s input buffer, and with the ability to add more Mosfets.
The Single-ended stage is similar to the Aleph amps, the difference being a fixed Constant Current Source instead of the Aleph CCS (which dynamically tracks the output) and the ability to add more mosfets.

This guide uses this PCB set - P-BAC-S4V20 - Burning Amplifier Complementary Bias and Output Set for the BA-2 & BA-3 (Requires a gain stage; Makes 2 channels; Rev 2.0) - Circuit Boards

Either gain stage can be used with either output stage. So not counting the PSU voltage or number of output mosfets there are 4 versions of this amp;

Differential FE, Complimentary output (BA-2)
Differential FE, Single-ended output (BA-1)
Complimentary FE, Complimentary output (BA-3)
Complimentary FE, Single-ended output (BA-3 SE)

Acceptable PSU voltage is from 20-32V, a bipolar supply is needed, you may utilize the diyAudio PSUv3 board or something similar. —

Universal PSU V3 - Circuit Boards

Of course, you will get more output power with higher voltage, at the expense of more heat. (Do you see a trend here…? 🙂 ) There is an upper limit to voltage, approximately 32V, as the input Jfets will start to become very unhappy at voltages much higher. (Of course, you can add a cascode circuit to the front-end to protect the Jfets from higher voltages, but there is no provisions on the PCB to do so.)


Anyway, this guide will show the construction of a BA-3 — a complimentary FE with one PCB of complimentary outputs. PSU will be +/- 32V .

If you haven’t yet, please read this article before continuing. If you have read it, might as well skim over it again, it has lots of great information —

Nelson Pass BA-3 article - Burning Amplifier BA-3 - diyAudio


And as we are using the output stage from the BA-2, this article is quite informative and instructional to read as well -

Nelson Pass BA-2 article - Burning Amplifier BA-2 - diyAudio


Now the one question you will have when reading the articles is this - “How much power does this amp have?” Well, it’s a very fluid design, remember? (So Nelson never said any numbers in his articles, although the information is in the graphs…) But an educated estimate is as follows -

Complimentary output, 24V rails - 25WPC, 8ohm. More into 4ohm
Complimentary output, 32V rails - 40WPC, 8ohm. More into 4ohm.
Single-ended output, 24V rails - 25WPC, 8ohm. Less into 4ohm.

More output devices doesn’t necessarily make more power, but it does provide more current, making difficult speaker loads easier to drive.


Schematic


Front-end

In this schematic note that the Mosfets types are not shown. The suggested pieces are Toshiba 2SK2013 / 2SJ313 (hard to find) and Fairchild FQP3N30 / FQP3P20 (easy to find). I’ve built using both types and can tell no real difference between the Toshiba and the Fairchild. If using Fairchild, use 1K pots for P1, P2. These Mosfets do not need to be matched.


Bias and output.

Schematic Changes (Suggested)


On the Front-end board P1 and P2 can be increased to 1000ohm to help accommodate different Mosfets. (As mentioned in the BA-3 article)

On the bias board I strongly suggest changing R25 to approximately 12K, and P2 to 5K. This will give more range to the circuit to zero the offset, using Fairchild output Mosfets I found it impossible to zero the offset with the original values. Those two minor changes made everything work as designed.

If you have well-matched Mosfets the source resistors (shown as 1.0 ohm 3W) can be reduced to 0.68ohm 3W or 0.47ohm 3W. You will get more output power with smaller source resistors.


Construction


BA-3 gain stage (Front-end) PCB. Note that there are PSU connections (V+, V-, GND) for each channel.
Also raise resistors R10 and R11 as shown, you will need to clip test lead there to set this stage’s bias and DC offset.


As the 5U chassis has enough space to fit the Fe board as shown, I decided to do so, it took only 4 holes drilled in the back. It has the advantage of keeping the input leads very short and away from the power transformer, and also keeping all the PSU wiring located in the same general area of the chassis.


Completed FE board.




FE board wiring. The PSU connections to the FE board are on the back, to keep those wires closer to the chassis. Then can, of course, be in front if you wish.


The completed and installed FE board. Note that the output from the FE to the output boards is not yet connected and shown. (Nor is it visible in this photo, it’s blocked by the bottom of the film caps…)


The diyAudio chassis is modular to the point that it’s easy to loosen a panel and make more room when construction get tight.



Complimentary output PCB.


Complimentary bias PCB.


The two resistor network is 10K+2.2K as I had no 12K in a single resistor. Also visible is a 2K pot in position P2. in the end I used a 5K.


Complimentary board and bias board on 4U heatsink.


Bias board connections - please note the extra washers raising the standoffs and PCB to clear the resistors underneath.


The bias/output connections are visible here - the black and red twisted pair is V+ and V- from the PSU, the white wire is the signal from the FE, labeled “D”, and pink is the speaker output positive (+). Speaker negative (-) is from the PSU GND.


Top view bias board.


It’s a bit busy, but not too bad back at the PSU connections.





Looking into the completed amp.
(Some may be asking, were did the big blue film caps go? Well... In a moment of extreme clumsiness I touched the iron against one of them while soldering another connection, and burnt a hole through. Whoops! Not having a direct replacement, I reached into my box of bits to see what I could come up with, and found some 10uF Silmic II and 0.10uF Rel-Cap film for bypass. That combo sounds great!)


The diyAudio soft start PCB. Not strictly necessary, the CL-60 thermistors in the primary circuit found in the original PSU work great, but this is kinda cool as well… Use the thermistors or the SoftStart.


If you center the LED and use bright blue ones, the glow comes out of the vents without shining out too bright… It's a nice look.

Power Supply

A stereo BA-3 requires a bipolar power supply from (+/-24V) to (+/- 32V). For 24V rails you need a 18V+18V (or 36V Center Tapped) transformer of suitable VA for your number of output devices. (a good rule of thumb is 50VA minimum per stereo pair of devices) and capacitor bank of 60,000 - 80,000uF per rail or more. I.E., a single output board, holding 3pr of Mosfet per channel (12 devices total) will need a 300VA transformer at the minimum. Most people will sure a 400VA. That’s fine. If you have more devices, you must have a bigger transformer. The other rule of thumb is you don’t want more total bias (in watts) than 1/2 of your transformer VA. More about that in the bias section.

The 32V PSU needs a 24V+24V (or 48V Center Tapped) transformer, and PSU capacitance of 60,000 - 80,000uF per rail or more.

Although not the exact PSU as shown in the Nelson Pass article, the diyAudio PSUv3 circuit board can be used to make a suitable power supply for the any of the Pass/Firstwatt amplifiers.

Using the PSUv3 board allows an easy addition of dual diode bridges, which will help keep the transformer mechanical noise to a minimum, and other benefits such as LEDs on each rail, room for (8) capacitors of up to 35mm diameter, the ability to use many different styles of connectors on the board itself, and not to mention the convenience of having everything on one PCB.

The diyAudio universal PSU v3 was made with the requirements of this very amp when it was designed.

The PSU shown in this guide has 50V caps of 18,000uF each, and a 24V+24V, 600VA transformer. (This happens to be the same PSU as used in the F5T guide.)

A build guide for the PSU itself can be found here - http://www.diyaudio.com/forums/powe...circuit-board-v3-illustrated-build-guide.html

Chassis

This is a high-wattage Class-A amplifier. It has lots of excess heat that needs to be dealt with. The 4U chassis can mount one PCB (6 devices) per heatsink. The 5U can mount 2 PCB (12 devices) per heatsink with a little creativity. But with 12 devices you will need to run at a bias amount (slightly reduced) that won’t overwhelm the heatsinks. (No worries, it will still sound fantastic!)

The 5U and 4U Deluxe chassis from the DIY audio store are basically identical except for size and that the 5U heatsinks are 2 pieces per side, so the guide for the 4U chassis is suitable for the 5U as well.

An illustrated guide to building the Deluxe Chassis (4U) can be found here - http://www.diyaudio.com/forums/parts/245959-illustrated-guide-4u-deluxe-chassis.html#post3704810

Testing and Powerup

Bias

Front-end

The procedure for setting bias on the BA-3 FE is almost identical to setting an F5, so this might seem familiar...

The Front-end bias and offset is separate from the output section. Do the FE first. Heck, you don’t even need to connect the output section to bias the FE.

Adjustments (Bias and Offset, set with P1 and P2)

This is easiest with three DMM.

Shorting the input jacks is very helpful, although not strictly necessary.

Before power up, dial pots P1 and P2 to 0 ohms . DON'T adjust P3 during bias

Place one voltmeter (Set to DC volts) across R12 - to observe DC offset

Place a voltmeter (Set to DC volts) across R11 another across R10.

For test - slowly dial up Variac ( presuming that you have one , as man with many skills) up to full mains voltage , observing rail voltage at PSU ....... thinking about max cap voltage ( 25V as in FW ? ) , because with 0 Iq PSU is unloaded and voltage is maxed (It’s useful to have another meter for this…) If nothing is smells bad, and the magic smoke is still in the circuit - leave Variac at full mains ;

IF you don’t have a Variac, you must build a lightbulb mains lead. (with a 25W bulb)

What's important - Iq (measured as the voltage across source resistors; the Mosfet bias) must be very low , offset is irrelevant in this moment .

Now turn one pot one turn ( assuming that you have multiturn pots) then turn other pot one turn. Continue, one turn at a time on each pot until something happens.

Observe voltage across resistors and output DC offset.

Proceed one then second pot , again just one turn

Observe Iq and offset

Again one turn + one turn

Now you are probably in range when you can see which pot is pulling offset in right direction - to 0 . It will feel like one of the pots is controlling the bias on both sides, and the other is controlling the DC offset.

It’s best to increase the bias a bit, and then zero the offset. As you zero the offset you will decrease some of the bias, so it will be two steps forward and one step back. That action is normal.

As you increase the bias and zero the offset, remember to always keep the offset near zero. If you run out of turn on the pots, determine your max bias, with zero offset. (It’s useful for troubleshooting)

Proceed iteratively with pots , while you set - say - 75% of desired bias, with zero offset. Remember, full bias is 1V across R10 and R11, with zero offset BEFORE the capacator. If you measure after the cap there should always be no DC.

Now - put lid on box and let it cook for a while - until you get thermal equilibrium on heatsinks

It's best to use wire/clips to leave those voltmeters in place ;

Open the lid , up bias to - say - 90% of desired one ,while maintaining offset

Put lid on , let it cook.

Check again.

If all is OK - move voltmeters for Bias and offset to other channel and repeat procedure.



Output section -

Do this only after the Front-end is set.

DC offset is adjusted by pot P2 on the bias board. Place a DMM set to DC volts on the speaker outputs and adjust for zero. If you have DC offset that drifts rapidly, it’s likely the TL431 is faulty. Replace.

Bias is adjusted by potentiometer P1 on the bias board. It’s measured by a DMM set to DC volts placed across any of the Mosfet source resistors. To start, set 0.25V measured across the 1.0ohm source resistors.

Use it few days at 90% of desired bias , then check and set to 100%

Remember - temp. equilibrium with lid on is important.


How much bias you can run is determined by a few factors, the most important being heat - the heat of the heatsinks, and the heat of the mosfets themselves.

The simple rules of thumb are -

HEAT = No more than 55C heatsink and 65C Mosfet. (The best place to measure Mosfet temp is pin 2)
TRANSFORMER = The amplifier’s total bias (in Watts) should be no more than 1/2 the VA of your transformer.

How do you determine watts? Simple - measure your bias current, the voltage drop across the 3W source resistors. Let’s say you measure .3V . Divide that by the value of the source resistor. If using 1.0 ohm, your answer is then .3A (.3 / 1 = .3) — but if using 0.47ohm resistors, a voltage drop of .3 is now .64A (.3 / .47 = .637) Back to the example using the 1.0 ohm resistors, multiply by your rail voltage, 32V, so each device will have a bias of 9.6W (.3 * 32 = 9.6) then multiply by the number of devices - 12 in this amp, (12 * 9.6 = 115W)


Setting P3

BEFORE installing and soldering P3 it’s best to adjust the pot so you have equal resistance from pin 1-2 and pin 2-3.

If you didn’t set it, determine how many turns the pot has. Run the pot all the way to one limit (they usually click) and then turn the adjustment the other way for 1/2 of it’s turns. (I.E.,if a 25-turn pot, adjust it 12.5 turns.)

Assuming well matched Jfets the neutral position is going to sound really nice, with 2nd harmonic dominant at the 1W level. IF you have access to a distortion analyzer, or a high-resolution FFT (or both…) give the amp a 1K test sine wave that outputs 1W into your load resistor. Then adjust P3 as necessary for the harmonics you prefer. If you adjust for minimum THD, you will likely have nulled out most of the 2nd harmonic and made it 3rd dominant, which in my opinion makes it very fast and clean, at the expense of soul. YMMV.

Anyway, if you DON’T have a distortion analyzer or similar, take careful notes and turn the pot a few turns (or more) in whatever direction you want and see what it sounds like. It’s a subtle change, but I think you will sense something. You can refer to you notes and see where you like the pot the best. And if you ever get lost, set it back to neutral, (with the power off) just bottom the pot in one direction and set it back to 1/2 it’s travel.


Lightbulb Mains lead notes -

If the bulb ever turns on and stays bright, you probably have a short.

Normal operation when turning on a cold amp will have the bulb glow bright for a second or two, then dim, perhaps off. (this is the capacitors charging, then full)

As you increase the bias of the amp the bulb will glow brighter, and this is linear with the bias amount. A fully biased amp can get the bulb to glow very bright.

You cannot set full bias with the bulb in place - as it increases the bulb will glow more, limiting the voltage to the amp and all the readings will be wrong compared to when the bulb lead is out.

You can, however, set the initial bias with the bulb in place. Start the procedure, turn the pots until something happens, and set, at maximum, 0.1V across the source resistors and zero offset. Getting the pots started this way is a good idea. Remember, this is with a reduced voltage, and the pots will make the circuit draw MUCH more bias when the normal mains lead in used. Expect to measure 0.2V or more with a normal cord. Continue biasing in small steps, always trying to keep the offset near zero.

Hi Folks; Minor panic here; A VOX Escort Bass 50 landed in my lap and is quit sick.
It is a capacitor coupled amp so the voltage between the output transistors should be half of B+. (80 V) It was around 19 V until some probing and now it is closer to only 1 volt.
All the transistors seem to test OK in circuit. It is a very simple amp but it has me stumped at the moment. Here are my voltage measurements;

Tr 1 E 2.1
B 9.4
C 0.0

Tr 2 E 0.7
B 0.0
C 0.9

Tr 3 E 1.5
B 0.0
C 0.9

Tr 4 E 2.3
B 0.9
C 72.0

Tr 6 E 0.01
B 0.58
C 1.4

Tr 7 E 1.8
B 2.3
C 72.5

I have got a HK audio lucas nano 300 in for repair. The issue was the unit not powering up, no indicator lights. Opening up the unit I found that something was shorting out +15V and -15V power rails. The culprit was 2 tantalum capacitors on the preamp board. There were actually 4 capacitors and it seems to be that 2 capacitors are in parallel with the 15V and -15V rail.
After removing the two shorted out capacitors I powered on the unit. This time the unit sprung to life but the amp is on mute mode. The indicator light is red and the LED on the main board labeled 'mute' is also lit. I measured the power rails and everything was ok and stable.
During troubleshooting one of the remaining tantalum capacitor on the preamp board shorted. So I have replaced all the capacitors now, there are no shorts now but the amp remains in mute mode. I tried playing back audio thinking that amp was in idle mode or something. No change, no sound but I heard very faint audio from the small satellite speakers.
I couldn't find any service manuals online, which makes the troubleshooting that much harder. I emailed the manufacturer but they are not willing to hand out the service notes unless its their authorized re-sellers, even for their legacy products. Any help on getting the service manual would be really appreciated.
The amplifier chip is LM4780. Nothing seemed to be shorted there. One thing I would remark is that the -VEE pin is tied to ground. I thought it would be connected to the -15V.
I traced the mute pin track to a SOT26 package transistor, the markings on it is '1Ft'. I couldn't find the pinout, knowing this would also help to figure out why the amplifier chip is mute.
Any help on this would be really appreciated.
Thanks in advance.

hi fellows, have been reading the original A75 publish and got a few questions wondering if i can find consultation here.

my electrical engineering study experience went no further than high school level.
DIY audio-wise, have successfully assembled and run AMB β22 singled-ended and balanced in these past 3 years.
started reading and assembling an A75 these 2 months.
can sense my understanding for audio amplifier components and circuits growing, but still won't say i am knowledgeable a all.

1. output stage circuit
   so i see in the amplifier wiring figure depicted in Part 2, it has speaker+ output connecting line coming from 'right in front of' the output stage circuit, rather than having OUT going through the output stage and then connect to speaker.
   i understand that the output stage is common drain mode in parallel, and it takes signal input from DRV+ and DRV-, right? so what would OUT be comparing to DRV? because in the complete amplifier circuit in Part 1, the OUT goes in to and through the whole output stage, and comes out as input to speaker terminal.
2. gerber drawing of power supply board
   is there an error with the section of where transformer secondary output goes into regulated circuit? R3 and R4 should definitely be between C4, C5 and AC, right?
   same thing with transformer secondary + and - marking in the wiring figure. (but probably most DIYer can make out these typo so no big deal?)
   after reading the article in these 2 months, i am 'guessing' there are minor errors with the gerber drawing but circuit diagram of amplifier and power supply are correct.

Would appreciate guidance on both A75 as well as suggestion on reading/studying direction to solve these questions.

Hello everyone, these last months I started designing a more accomplished NAP250 clone, I may have been too ambitious and suddenly I end up with a small problem of oscillation of the main regulator.

I respected the Naim audio diagram with the difference that I placed the amplifier and the regulator (NAPS) on the same PCB, routing level it was complicated to do.

After wanting to improve the amplifier I replaced the MPSA56/06 transistor references with ZTX753/653 which are more robust

the drivers and output transistors were also replaced by
TTC3710B/TTA1452B
and MJW18020 at the output.

The output filtering capacities are at good esr for stability and those at the input too.

everything else works fine the amp the phase compensation etc I even added the TGM10 speaker protection which works and also a front regulator (like the NAP250 DR) but for the moment I dismantled the front regulator to focus on the NAPS which is faulty.

I specify that on laboratory power supply everything worked without problem and the oscillation was therefore not present, I think it is the ripple of the symmetrical power supply which is not supported by the regulator.

do you have any ideas as to the cause of the problem compared to the original design? or do you have a modification to make that could stabilize this problem?

thank you in advance I put you pictures of scope and the new design.

the oscillation is a 150Khz component which makes 100 mv on the negative rail and 50 mv on the positive rail.

Dear all,

Recently acquired a Sansui Sr525. It was spinning very fast and with high wow and flutter as measured by an Android app.

Did these and managed to bring the speed down to 43rpm on the 33rpm setting:
1. Replaced the fine pitch controls and VR1 and VR2 on the motor board.
2. Opened the microswitch and cleaned it as much as possible.
3. Replaced all electrolytics caps on the power and motor control boards.

It is the slowest speed I could get by putting the fine pitch control and the trim pots to the slowest setting.

I have since replaced the zener 5.1v and 2 ceramic caps near the dual transistor at the motor circuit, to no avail as well.

Any suggestions? Thank you very much!

looking forward to learn everything that i can from fellow users

As part of an experiment I am looking into how best to replace the clocks feeding an Intel C222 chipset on a PC motherboard. The idea is to replace the crystals with XO clocks with separate power supplies. The power supply with be a 3.3v lifepo cell.

The suitable 25MHz XOs that I can find (eg https://uk.farnell.com/jsp/search/productdetail.jsp?SKU=2394158) appear to have an output signal voltage (high) of a minimum of 90% of VDD. Seeing as the lifepo outputs around 3.3v this means around 3v o/p signal voltage. However the chipset documentation states that the voltage should be no more than 1.2v.

I have read through a few threads on the subject of replacing clocks here and elsewhere but none seem to mention this issue. Is it a non-issue that I can ignore? Or, as I'm guessing that I shouldn't, how can I reduce the output of the clock with as little disruption to the signal as possible?

Many thanks,
Crom

I'm currently working on a high-power amplifier and I'm exploring different input stage designs. I'd love to get your insights on the performance and sonic characteristics of op-amp based input stages versus discrete transistor-based input stages.
I would greatly appreciate it if you could share your experiences and attach one best input stage schematic for each category that you believe excels in performance.

Looking forward to your valuable inputs!

G'day Guys,

I managed to find a 2KW single phase variac for 100 kiwibucks a wee while back.
https://www.aliexpress.com/item/100...OCdnqQdW&utparam-url=scene:search|query_from:

One of these but without the fuse holder which is problem #1
Problem #2 is the analog meter is pretty poopy. At 230Vac output according to my DMM the analog meter reads 220Vac.
Problem #3 is the connections. Having to wire things in ever time will be a pain in the buttocks.

So my evil plan is to graft a large plastic jiffy box on the front so that I can mount the extra bits to make it more usefull:

• Fused IEC socket for power in
• A digital meter: https://www.aliexpress.com/item/100...order_list.order_list_main.131.68d61802ltfBqQ
• Illuminated power on switch
• A slimline NZ power socket for the outlet.

Here's the block diagram.


So far I have tested the variac to make sure it works as intended: check.
I checked the accuracy on the built in analog meter as per above. 10Vac out at 230Vac
I also checked the function of the digital meter: much better. 2Vac out at 230Vac

Next up is to start cutting into the jiffy box to mount the goodies.
After that I will need to figure out how to mount the jiffy box to the front of the Variac chassis. Probably rivet nuts.

I have made two surround ”eggs” to complement my chn110 tower speakers , using the similar looking but much smaller chn50 driver in a small cabinet.

Two IKEA 12 cm wooden bowls and a 3 inch 22mm Mdf ring was glued and painted in black. I used a round black cable and making the drilled hole in the speakers very tight so they dont need any connectors. Inside there is sheeps wool and no crossover at all.

These speakers will be mounted on two speaker stands with a round base.

The reason I made these speakers is the new software in WiiM ultra , allowing dolby digital 4.0 with the help of my older WiiM PRO and my Hypex ncore 125 amplifier.

Feel free to chip in

Hi friends, a while back I built this amp for a friend(with some changes). He's been using it for several years without any issues. A few weeks ago, he told me he was hearing a noise on the right channel. I thought it was the 6v6s running out. I set up the oscilloscope and detected a noise/oscillation in the negative part of the sine wave that I can't detect. Can you give me any clues on how to locate the fault? Could it be the OPT? I've already tried another 12ax7 and re-soldered it.

The red marks are where I placed the oscilloscope and found the noise.
The other triode of the 12ax7 and the other 6v6 work ok, to eliminate the potentiometer.
I inverted the 6v6 too.

thanx a lot guys!!



https://diyaudioprojects.com/Schematics/DIY-Push-Pull-PP-6V6-Tube-Amplifier/

I have been using LifePO4 batteries for my FIFO and DAC project for a long time. And also ultra capacitor power supply recently. I'm very happy with their performance and the sound quality.

http://www.diyaudio.com/forums/digi...mate-weapon-fight-jitter-353.html#post4239435

http://www.diyaudio.com/forums/pc-b...i2s-dac-hats-raspberry-pi-57.html#post5478596

Both ultra capacitor power supply and LiFePO4 power supply are passive power source. They are totally different to all kinds of regulators which are based on feedback. The most important thing is the perfect load response, much better than any regulator.

Both of them are ideal solution for DAC projects with amazing sound quality. Ulara capacitor power supply is a little bit better but the difference is minor. However the LiFePO4 power supply would be cheaper and easy to integrate into a all in one solution.

I'll work on both for sure. But I'd like to start from LifePO4 power supply.


LiFePO4PowerSupply_1 by Ian, on Flickr

Ian

This is a group buy for circuit boards to make a diy clone of the First Watt F3 amplifier. This board set is designed to work with the diyAudio store UMS mounting pattern making life a little easier for those having UMS chassis.

The design is about 80% done and now it is time to gather input and make refinements before ordering a test set of boards to validate the layout.

The images below show the basics, and the .pdf has more details about the boards, preliminary pricing, and a tentative schedule for the group buy.

Here is a link to the F3 UMS Pattern Group Buy Sign Up Sheet

I will make every effort to post weekly status updates to share progress.

Need some help to repair a bad channel on Crown 400CSL power amp. Need a little help where to look. I seem to have a good signal up to C100 but signal after R101 seems bad. I made a couple videos:

Output off speaker terminals.

Signals at C100 input and R201 output.

Here is schematic: https://schematicsforfree.com/files/Audio/Products/Consumer/C/Crown CSL 460.pdf

Any suggestions appreciated.

A new wood enclosure in perfect condition, very solidly made of high quality plywood (no voids) with beautiful veneer, brass screen on top, vent opening on bottom, four pointed brass feet.

Overall outside dimensions 21" wide x 16" deep x 7-1/4" high, not including feet, 8-1/4" high with feet. Internal dimensions 19.5" x 14-3/4" x 6". Front opening 17" x 5-1/2". Screened top opening 14" x 7". Bottom opening 11" x 6".

$200 plus shipping.

So I am a DJ and occasionally do live shows corporate work as well. Our typical event is 300 people or less, mostly indoors but occasionally outdoors. I am looking to really make my load in/out as simple and easy as possible. Dragging VRX subs and SRX tops in and out of venues by myself is doable but I am getting older now and it seems like it just gets a bit more painful every year.

I would like to go with a Passive rig that can be run by two QSC GXD8 amplifiers or something similar. Keep the processing in the amps and have a simple 5U case at 35lbs. For subs, I have built two of single 15 enclosures using Beyma 15LEX1600nd. The enclosures are complete minus the handles. Waiting for the drivers to come in so I can get the COG right. They should weigh in at right about 55-60 lbs and are very compact. Supposedly they get decently loud. I guess we'll see. If they perform well I intend to build two more for outdoor work.

I am struggling a bit with a design for a lightweight 2-way top. But ultimately I would like to us an RCF HF94 coupled with 2 B&C 8MBX51 mid/low drivers. I would like to hp them at 80 to 90 hz and crossover at 900 - 1000. I spent several days in winISD and the attached screenshots are what I came up with so far. In this design I have baffle between the low and high frequency section to keep my volume down. Ultimately, I would like to achieve a true 125db and be under 40lbs.

So besides and suggestions you might have, I have two questions:

1. Is there anything wrong with using a rear port on a PA speaker? I really struggled to find a balance in enclosure volume and port dimensions that were reasonable without exceeding cone excursion parameters. And I could save a few inches in height if I could move the port to the back.

2. Is there a particular compression driver you would recommend pairing with the HF94?

Here they are, both K and K2 diagrams, may the interwebs never be void of them again!




For those who want to remove the Lpads on the Ks, here is an altered diagram:




Thanks to all who have contributed to this thread and a special thanks to @chrisng for his tracing and diagram skills! 🙂


--------- Original Post Below ----------

Hi,

I am after the crossover diagram for the Goodmans Magnum Ks.

In this post here: https://www.diyaudio.com/community/...sovers-and-potentiometers.112926/post-1971834 user alspe had previously uploaded the crossover diagram to google drive. It was some time ago though and the link is now dead. It’s not listed in the way back machine either.

I was hoping to contact alspe, but it looks like they are no longer a member here and I can’t tag them.

I have attempted to trace it, but these old xovers are a mess and I’m finding it difficult.

I thought it would be similar to the K2 but it’s not. Not only because of the Lpads, but the filters are different too.

Anyone got it or able to help?

For Sale

(2) New In Box, unopened SEAS L26R04Y D1004-04S speakers. Current Madisound price is $498/each.

I intended to make the Linkwitz LX mini + Sub, and never got around to it, I sold the LX mini a year or two ago, these have been on the shelf ever since. I'm sure somebody can use these woofers, they are by all accounts fantastic. 🙂

$390usd each + shipping


Stock photo

Hi All, been offline for quite a while, since i finished my major build. Despite it being a year long learning experience and trying to use best-practise on every aspect (within the limits of my requirements for a compact system) honestly ive never been totally happy with the sound. the subwoofers particularly have never really satisfied me, and the whole system seems to be missing something. The subwoofers (compact things with slot ports) do crank out bass, but its a bit resonant and boomy, and overall the system is missing "slam!"

i remember at the time, i had a laugh when somebody here described my chosen subwoofer drivers (https://www.daytonaudio.com/product/120/rss265ho-4-10-reference-ho-subwoofer-4-ohm) as "mud-shovels" and i assume the criticism was spot-on. i chose them since a) i got them for an amazing price and b) they allowed me to build the subs small (also they did have great reviews so im not a complete idiot)

so anyway, im evaluating options. specifically, im wondering if some other enclosure type might allow these sub drivers to sound better.. ideally also reaching higher to improve the punchiness of the sound. (they claim to go up to 600 hertz, id be happy with kick drum range at 2-300hz.) at the moment they cross over to my dual driver alpair fullrange cabinets (also ported enclosures) at around 85 hz.

Id not go higher with the current cabinets as first, they are not positioned well for stereo imaging if they go higher, second, the drivers are down-firing and third, with a 210 gram cone, they have a habit of jumping off the floor despite weighing close to 20kg.

i was playing with the idea of some kind of transmission line (pvc pipe?) or tapped horns, placed under or behind the fullranges, with the drivers forward firing.

i do vaguely remember however that these drivers were not well suited for tapped horns.

itll break my heart to replace the very pretty (imho) translam cabinets i spent months designing and building, probably with something 3x bigger and ugly. but if it doesnt sound good, whats the point?

any suggestions most appreciated.

Hate to see it go, but it's been gathering dust in the closet since I switched to an active monitor setup. I built this amp in 2016 and it sounds great. It has XLR inputs, but can easily be converted to RCA. It is quiet even with sensitive speakers.

Asking $500 obo. Local pickup preferred, but willing to ship within ConUS. I am located in San Francisco. Sold

Plan on post #83
latest sim and hr file on post#121


###########################
On my quest for a PA sub design that will let me reach 140dB SPL with 4 cabinets and do not use the 700+ Drivers from Beyma, 18sound and B&C that are staples
in high output PA cabinets
i looked for modest options and found a car driver that fits the criteria

since my hornresp skills are very modest, i can not simulate from scratch but punch in different drivers in to existing designs.
i think i found a winner combination.

i will take 2 sheets of ply and 2 skar drivers
143 a piece per driver is 286usd for 3kw power per cabinet
the original design costed about 325 bux in 2013, i calculate that this will cost about 400 to 450
wood plus , handles, casters, paint.

do you guys remember this LAB12 based design ?
https://www.diyaudio.com/community/threads/325-lab-12-based-pa-tapped-horn-35hz-extension.232219/



BP1 was very kind to help and do some mods to the original design that can only house a LAB12
he made S1-S2 baffle length longer so to accommodate 2 skar 12" drivers inline
using 4 cabinets with 2 skar 12 DDX drivers @1.5kW per driver (3kw per cab) we get this









with HP and LP applied we get this


what you guys think?
tweaks ,mods, and improvements are welcome
Max.

To spice up my boring 2 way build I am going to try some 3d printed edge diffraction pieces to see what difference they might make.

I will be starting with this aerofoil/teardrop shape. This is a pretty small one but I can make it wayyyyy bigger which is probably what I will try next.

Does anyone else have a shape they would like me to test? Let me know. Let's do some science!

Hi folks, I've noticed a lot of misinformation about people using ferrite (Fe2O3, or commonly referred to as rust) resistors in audio electronics and other electronics. It's actually a horrible choice of material for a resistor. Ferrite is used in antennas! If you want to get hacked offline or to pick up interference from random crap, ferrite is a great choice of material in your resistors.

I think a lot of you are making your own electronics specifically to avoid talentless hacks screwing everything up. If that is the case, you are perhaps better off with some sort of ceramic material for resistors, just make sure your power rating has sufficient watt throughput capability.

The benefit to using ferrite is that the resistors are very small. If you are shielding everything or are not worried about talentless hacks ruining your fun, ferrite is a great choice. Otherwise, choose resistors made out of a different material -- especially if you are in aerospace.

I just got a VPI SDS but I don't think it's operating correctly.

I connected it to my VPI TNT Jr and it worked but pressing the rpm button woudn't do anything nor would the up/down arrows. I messed around with it and was able to change speed by simultaneously pressing rpm & down arrow. I could change the frequency by pressing rpm & up arrow. This would lower the frequency but I can't figure out a way to raise it. I also can't get into setup. The output voltage & frequency match the display.

I assume this is a firmware issue?

Thanks.
Kevin Looker

I‘m trying to simulate the LM3886 with the LM3886.lib from Texas Instruments in LTspice XVII. The schematics is from the datasheet. When I run the simulation, the error log is telling me:



I assume that something is not connected properly but I can‘t figure out what it is?
I renamed the LM3886.asy to LM3886.asy.txt and the LM3886.lib to LM3886.lib.txt, so they can be uploaded with this post.

The Texas Instruments Support can't help with LTspice XVII, because they support only TINA-TI or PSpice.

his has been discussed on and off in the forums... I finally got around to designing and building an interface for using a sound card for making masurements.





Details are here: Soundcard Interface

Pete

Dear members,

I'm looking for a Krell KAV-400Xi KAV 400 XI schematic / service manual.
left power amp is broken.

This build thread associated with this GB:

http://www.diyaudio.com/forums/group-buys/229358-my_ref-fremen-edition-interest-group-buy.html

On the project's OneDrive folder it's available a PDF version of the tutorial, in addition to schematic, BOM, etc..

Also on 7/2013 I've added a video on YouTube of the SMD soldering part:

Apart support and sharing place for builders, goal of the thread is to generate content to complete the tutorial.

Builders, please post your experience, problems, pics and whatever related with your FE build... 😉

Good day,

Anyone happen to know what diode was in place at location D6? It was completely melted out of the amp when I got it. The MJD32C burned the pad up pretty good.

Thanks in advance!

I have a strange setup I'm looking to update. I do the bulk of my music listening in my kitchen and the only place to put speakers to get decent soundstage around the whole room is on the ceiling. So I stumbled on DML speakers and made some 2x2' panels from styrofoam. With some heavy DSP and a sub they sound great honestly.

However I am just kind of bored and looking for a change so I want to keep the same ceiling hung config but build new speakers that address the shortcomings of the DML panels. The shortcomings are basically general inefficiency, high LF rolloff (about 200-250Hz from what I remember) and the heavy handed DSP to flatten the response. The great thing about them is the imaging- there is basically no beaming, at least to my ears, which is great considering how much I move around the kitchen.

So I am looking to make new 2x2' panel speakers with conventional drivers that have minimal beaming/max dispersion all the way up the frequency range. My gut says to just pair an in ceiling speaker with a high QTS 10-12" driver and call it a day. But I'm also open to running a WMT 3 way setup as well. Imaging doesn't have to be perfect.... I just don't want any high frequency hot spots in the room. What do you recommend?

Great day guys, this amp keeps blowing out the rail caps mainly the negative side, what could be the issue why it’s doing that, power on ok, then even with low volume it’s just pops the caps, I’ve change them but there seems to be an issue otherwise.

Good Morning. Here’s my Second post to clean out some stuff I don't need.

1. I have a lot of Gotham Audio wires and connections I bought from swisher land and shipped to my house. Never used.

2. I have a few Belden speaker wires and so on for sale. Never used.

3. I have some Canare Wires all speaker wires and the 4S11 (O.F.C.) I paid more for per. Foot and the regular 4S11 cables. Never used.

4. I have some whirl wind speaker wires and cbi Speaker wire and West penn wire as well. I have Redco’s only House brand speaker wire too. I have very little Dayton Audio wire but, I have some.


I have some Binding post from Dayton Audio and Gotham Cables and RCA plugs as well.

I have quick connections Gold and silver ones for speaker cable and driver hook ups.

I can take pictures and send them to anyone who wants to see pictures of the products.

I would love to sell local it would be a lot of little things to ship out. I also Have the wire in a sealed container.


E mail me with Questions about things for sale. I can be reached at Jmboo1922@gmail.com. Thanks Jeff

diyAudio Universal Power Supply Circuit Board v3 illustrated build guide. (October 2013)

(Any photo with a link directly below will go to full-size file of the photo)

This build guide will show a typical use of the diyAudio PSU v3 circuit board. This specific build will be suitable for any of the Pass/Firstwatt amps that use a +/-25V supply. If you need a higher voltage make sure you use capacitors of a suitable voltage rating for your project. You may always have a higher voltage rating, but do not use a cap with a lower voltage rating than your rails.

Useful Links

BOM - https://www.diyaudio.com/forums/images/diy/store/board-documentation/P-PSU-1V30/P-PSU-1V30-bom.xls
Schematic - https://www.diyaudio.com/forums/ima...mentation/P-PSU-1V30/P-PSU-1V30-schematic.pdf


PSU18 - My Photo Gallery


((Do not connect 2-leg TO-220 diodes as shown. See photos in 'heatsink' section.))
PSU36 - My Photo Gallery
Fully stuffed






PCB scale

Dimensions -


PCB dimensions





PSU14 - My Photo Gallery
The heatsinks are one inch post spacing. Look at the BOM for a specific part suggestion and find something similar that you can use. The sinks I used in this guide are of the same outer profile, so they fit the pads perfectly, but are quite a bit taller. A number of parts will be available that will work.


IMG_2134 - My Photo Gallery
This board can accept capacitors of up to 35mm diameter.



Equally important is the lead spacing - the caps should be 10mm 'snap in'. 10mm radial leads will work as well, but usually the bigger diameter caps have the 'snap in' leads.

For more information on dimensions of the specific parts, please consult the BOM for suggested parts, and cross-reference from that part's datasheet. http://www.diyaudio.com/forums/images/diy/store/board-documentation/P-PSU-1V30/P-PSU-1V30-bom.xls

Board features -


The bridge diode section of the board can utilize either TO-247/TO-3P (larger) package devices or TO-220 (smaller). If heat dissipation / heatsinking is not an issue, you could also use conventional axial-leaded diodes. (Not shown.)


IMG_2135 - My Photo Gallery
If you would like to use snubbers on the rectifier diodes you will find that there is room for them on the top of the PCB, and inside the heatsinks.


IMG_2141 - My Photo Gallery
If you don't find enough room there, or would like to try a different snubber layout, there is plenty of place to connect on the bottom of the PCB, as you will always have one of the d=sets of diode pads empty - you can only use one type of diode at a time, for example if you are using the TO-220, the TO-247 pads will be empty and you may make connections there.


IMG_2142 - My Photo Gallery
For designs that require one, there is also room for a snubber on the output. (Per rail)

Also worth noting, in this photo you can see the multiple solder pads for the output - the row towards the edge is for the euroblock connectors, and the inner row, with the larger pads, for wire. There is also a place for a blade terminal. (Near the board edge, on the outside. To be better illustrated in a later photo.)



Building / Stuffing



PSU41 - My Photo Gallery
This photo shows all the parts that will be used in this guide.
Starting at top and circling clockwise -
Capacitors and 'euroblock' connectors
(8) filter or 'pi' resistors
Diode heatsinks and diodes (TO-220 package shown)
(2) bleeder resistors
LED and LED resistors
AMP terminal blades

As this board has the scoring to let you separate it if you so choose, you need to notice that there is no connection from the diodes to the first capacitors nor across GND. These must be connected.

The PCB has no connection from diodes to capacitor.


The PCB also has no connection to make GND.

Since I am planning on keeping this PCB intact for the amp I am building, I need to make a connection form the diodes to the capacitor bank, and a connection to establish ground.


You can see all the links here (diode links not soldered in this photo)


GND links. The pads on most of this PCB are all through-plated and big enough to solder from the top if you choose.


PSU28 - My Photo Gallery
In general stuffing should be from the smaller devices to the bigger devices, so the resistors and such should be first. The filter resistors are on the outside, then the LED and LED resistors (the small brown one) and inboard are the bleeder resistors.
The silkscreen markings at the LED pads are slightly obscured, and the break in the circle, indicating where the flat of the LED should go (cathode, negative, short leg) is a little bit confusing. The legs of the LED go as shown. You can also see another link at the top of the PCB where I joined GND together.


The blades are actually taller than the euroblocks, so don't solder them first!



PSU27 - My Photo Gallery
The output edge shown with all the connectors in place

Capacitors -



As mentioned before, this PCB can accept caps with 10mm lead spacing and up to 35mm diameter. This photo shows 35mm caps next to 30mm. You will also commonly find some appropriate values in 25mm diameter.


PSU32 - My Photo Gallery
The addition of the large solder pads has obscured the markings on the PCB and the ' + ' mark is somewhat hard to make out. In each case the Positive side is marked with the open rectangle and the negative the white or filled-in rectangle. Remember that electrolytic capacitors are usually only marked on the Negative side.


PSU9 - My Photo Gallery
Note capacitor direction - you can see the negative markings on each capacitor.

Heatsinks -





The heatsinks used in this guide were chosen as they were of proper dimension to fit the PCB, and in-stock at the time I ordered them. They are a little tall, but as Nelson Pass says, there is no such thing as too much heatsink… I do suggest you try to get something that will fit a TO-247/TO-3P package as it will also mount the TO-220, whereas the slightly narrower inner profile of this heatsink will only mount the smaller diode. Regardless, it's quite easy to get really nice, suitable diodes in whichever package - you want 20A, 200V minimum diodes.


A little grease is helpful on the full-pack devices. Secure to the heatsink with a nut and screw. This is a 4-40 screw, about the same size as M3.

Please Read - If you use a conventional TO-220 diode or TO-247/TO-3P it's a very good idea to use an insulator between the device and the heatsink. But it's not necessary - although if you choose not to the heatsinks will probably be live. The heatsinks themselves solder to the PCB and are in holes that have no electrical connection, and aluminum anodize is actually not very conductive, but I would still suggest using an insulator. (Or a full-pack TO-220)



Feel free to snap off the diode section and use bridges. They work and sound great!

NOTE - I strongly suggest not separating the capacitor board if at all possible. With it intact, you can run multiple jumpers (as shown) to tie GND together and have a low-impedance, and therefore quiet GND. Splitting it will complicate making a quiet circuit. FYI.


Example wiring.

I’m recently new to the hifi hobby and have always been intrigued by building things yourself. I’ve studied electronics and embedded systems in schools even though IT was always my major. Now I’m looking to re-ignite my interest in electronics via hifi. 🤓

Hello.

I have two couple of speakers with altec lansing 409-8c coaxial drivers, each of them driven by an integrated tube amp. One couple of these altec goes first through the speaker level imputs of two vintage Yamaha subwoofers. A couple of pictures, so you will understand:






These Altec speakers have a sensitivity of 97 db, nominal impedance 8 ohm and minimum impedance 6 ohm, and an advertised frequency response of 50 hz/14 khz.

I would like these speakers to be driven in parallel by just one amplifier, each channel going first through one active subwoofer, then two coaxials in parallel and, in order to have a higher impedance as a result, I would like to add a 16 ohm vintage compression driver and horn for each channel, with a crossover like EV c35.

Do you think it will work? What kind of impedance will I have? What vintage compression driver and horn do you recommend? What crossover?

(I can't build a crossover myself, I'm quite a novice)

What kind of sensitivity will I have with two 97db speakers in parallel for each channel? 100 db?

In short, each channel, after the amplifier, there will be a subwoofer, two coaxial drivers Altec 409 in parallel, then a crossover and a compression driver and horn. The horn will go on top of two speakers.

In short, if this is feasible, what I lack is compression drivers, horns and crossovers, and also the knowledge. Compression drivers and horns should not be very heavy. I've got fibromyalgia and can't lift heavy weights.

Thanks in advance.

Hello Everyone how are you all 🙂. My diy Lampucera has arrived. It has not come with any instructions. It has two power supply transformers I don't know where the one with yellow wires connects. As I look at everything to do with the dac it's starting to become clearer what to do and one of the things is ask a friend of mine who solders better than me to help me. To test it to see if it works do I need a metal case first and is everything I need to get it working in this kit I know I need a power cable to connect it to the on off power connector that comes with it.

https://www.ebay.co.uk/itm/18672783...46UT_E9QjS&var=&widget_ver=artemis&media=COPY

Hi All,

Im a hifi enthusiast from Malaysia with limited DIY experience. I picked up hifi during my university time in the mid 90s in the UK. It seems the bug is still with me until now. I run 2 sets of stereo separates, one with ole chrome and the other with olive naim amplifiers at the heart, sources are Arcams and Audiolabs and speakers are Epos and Mission.

3 days ago, my trusty 30 year old Arcam Black Box 50 stopped working. One thing I notice is that the sync lock light is stuck ON all the time (cannot be switched off) and there's no red light at the sync lock terminal at the back of the unit. My go-to CD player repairman asked if I can get a hold of the correct circuit schematics. He's got the repair manuals, but its not sufficient it seems.

I was wondering if anyone here can assist me on this issue, or even help with the circuit schematics of the Arcam Black Box 50. I can be contacted via WhatsApp at +60123827078. Thanking all in advance and looking forward to making your acquaintances and sharing of ideas here.

I recently published an article in audioXpress (September 2024) about a new family of loudspeaker crossovers that I call "DFE Crossovers". The filters that make up these crossovers are derived from elliptic filters (giving rise to the DFE name) are characterized by:

• steep transition bands, up to ~150dB/octave
• a stopband that is finite in depth, typically 40dB-50dB but sometimes more
• excellent LP+HP summation with very low ripple
• low group delay (below the threshold of audibility reported in the literature)

The elliptic filter is described by more parameters and has more degrees of freedom compared to all-pole crossovers. This provides additional degrees of freedom, making it possible to trade off steepness, stopband depth, ripple, and group delay. I used an optimization technique combined with an objective function that attempts to balance all of these characteristics of the crossover and its constituent filters. These crossovers make use of two lesser-known notch filter responses: the highpass-notch and the lowpass-notch. When expressed as a series of first and second order stages, an elliptic filter uses only the LP-notch or HP-notch 2nd order stages, with odd order filters having a single additional all-pole LP or HP filter. I described the LP-notch and HP-notch in an aricle in the August issue of AudioXpress. It includes a suggested circuit for an analog-active implementation as well as a C++ code to calculate the IIR transfer function coefficients that can be plugged into a DSP processor that can accept them.

The DFE family consists of over 30 examples, having order from 3 to 8. Variations such as "squared" crossovers (like the Linkwitz-Riley crossover) and combinations of all-pole and DFE crossovers (AP-DFE), are included in the "family". The AP-DFE type can be implemented as a mixed passive+active hybrid, with the all-pole part implemented as a passive crossover and the DFE part using analog active or IIR DSP means. This has the advantage of suppressing harmonic distortion within the LP filter passband (see this Purifi tech note for more information).

The audioXpress article provides full details on the DFE crossovers, but I will provide a couple of examples below. I typically present the lowpass filter response, a zoomed-in view of the LP+HP sum, and the group delay of the crossover. The highpass filters is simply the lowpass mirrored about the crossover frequency. Please see the following attachments:

The elliptic-like response of these crossovers is well suited to loudspeaker crossovers because stopband attenuation of more than about 50dB is not necessary. Instead it is better is to quickly transition between passband and stopband (e.g. the transition band is narrow). Most non-FIR filters with such narrow transition bands would produce excessively high group delay that would cause audible phase distortion, but I have used the extra degrees of freedom to design the DFE Family filters to have sufficiently low group delay as to not give rise to audible distortion in the time domain signal.

Overall these filters offer an interesting mix of capabilties that has not yet been available except through FIR filtering. The DFE filters can be implemented with analog active circuits or IIR DSP, and remain easy to use and relatively lightweight. You can download information about the complete DFE Crossover family at the following link:
https://audioxpress.com/files/attachment/2777




.

As spin-off of thread below I build a unbalanced tube input board for my purifi modules as mentioned in the thread below.
https://www.diyaudio.com/community/...urifi-1et400a-amps.379211/page-3#post-7027789



Picture from Jasper84

I made a PCB for the unbalanced version, a 6n6p tube with mu-follower topology.
The preamp has a gain of 9 times and no problems to drive the 2k2 input impedance of the 1et400a modules.
Timing circuit around Q1 has a 13 seconds delay. This gives the tubes time to heat up without getting a big thump and shutdown the amp modules without strange noises.
Led D2/3 is on the “amp on” signal and can be mounted in a B9A socket with a hole in the middle. Tube bottom will light up when amp is on.







Combined this input board with 2 x 1et400a Purifi amp and Hypex smps1200a400 and smps 265v/6.3V then you get amp in picture below.



This amp is a pleasure to listen to.

Would anyone have a Dynakit z565 output transformer, either a new or a used one in good electrical condition that you would be willing to sell?

Forgive me while I learn these full bridge amps.

This amp powers on, makes rail voltage but has clip light on.

Output doesn't seem to be switching. I believe if I lift Diodes 10/11 that will force the MIC8280 (U7) to send pulses? The driver ICs are CSC3127's? Can't find much of anything on them. They then seem to feed 2 pair of 1797/4672 buffers.

What's the best plan of approach here?

Outputs don't seem to be shorted.

One 1 set of outputs I have G(55v) D(124v) S(55v)
Other set of outputs I have G(0V) D(55v) S(0v)

Same on both sides of the amp.

I bought this massive transformer several years ago and never realised this project. It is the 15 watt OTL with EL509 Tubes.
It is made by a very well regarded German company, it also has a magnetic shield.
Some parts come with it, see Photo.
I also can add eight 6s45p tubes for 70€, they should work fine.
Preferably shipping to Europe, as it is pretty heavy which will drive shipping cost up.
Price 200 Euro for the whole package including tubes, 130 without.

(update) Wellers solding station not sold. Thanks everyone. Good Afternoon. I have the Following Items for sale. Fell feel to make me in offer even after I put what am asking for? I can also send pictures. Here is my
E mail. Jmboo1922@gmail.com

Items for sale.

Sold1.Bass box and Crossover pro programs with books cd and both product numbers. Asking $50.00 and You pay shipping. Books in excellent condition.

Sold/2.Dayton Dats v3 mint condition comes with everything and even the original box. I also thrown in the mass scale new and the Probe that slows down your speaker and so on and the original woofer test 2 from Smith and Larson with everything it comes with and even the box. and The winspeakerz and the subwoofer tool box program. Am asking $120.00. You pay for shipping. (If you do local pick up I will Give away a tripod and a 4x8 piece of acoustic foam to put around the tripod).

(Not sold yet)A. I have a digital Weller a soldering station with a soldering smoke fan. I’m asking $100.00. Brand new never used any of them. I have paper work on both. You pay for shipping.

I will only ship to the 48 United States. Thanks Jeff

2" Peerless by Tymphany - nice driver, right ?

https://audioxpress.com/article/test-bench-peerless-by-tymphany-full-range-2-pls-50n25al01-08

wait what is this ?



20% THD ? how ???

well ...

"For the distortion measurement, I mounted the Peerless by Tymphany 2” rigidly in free air"

he always does that ... FREE AIR ... WHY ??? he had it mounted in an enclosure for his other tests:

"I mounted the PLS-50N full-range in an enclosure, which had a 9” × 4” baffle and was filled with damping material (foam)."

but for distortion measurement it is now in free air ... "rigidly mounted" ... he says it like it's some kind of an achievement ... as if mounting it flexibly would produce a different result ...

that makes no sense ... of course without enclosure the low frequency of fundamental will get cancelled out by the back wave while the higher frequency of harmonics will not, causing the measured ratio of harmonic to fundamental to shoot way up to something absurd like 20% THD ...

does anybody actually believe that a driver from a major manufacturer would have 20% THD in the middle of the passband when measured correctly ?

why does he keep doing this ? isn't he the guy who wrote the loudspeaker design cookbook ? surely he knows better ?

what is going on ?

Omicron is:

• A compact, ultra-low distortion headphone amplifier that we developed jointly with @Rus2000 from the RCL-electro.ru forum
• Designed to work with 32 to 600 ohm headphones and tested with a range of over-the-ear and on-the-ear cans from AKG, Beyerdynamic, Grado, Klipsch, and Sennheiser but proved to be equally at ease with lower impedance headphones, such as 8-ohm AKG's K3003 3-way in-ear monitors and 18-ohm HIFIMAN's planar magnetic HE5XX; the ubiquitous white Apple EarPods (tethered ones, both 1st and 2nd generation) sound great with Omicron, too!
• Very musical, with pure, clean, liquid sound and perfect clarity even in the most harmonically complex pieces. Those who built the Omicron often report that its sound is addictive, and that it is hard to put the headphones down when listening to music.

First hand experiences:

The sound immediately fascinated me so much that I began listening without adjusting the quiescent current. You want to turn up the volume, no mess, even the quietest sounds are clearly heard, but at the same time the sound is very comfortable, not harsh, a beautiful three-dimensional scene. Very nice bass. In short, top notch!

Click to expand...

donovas said:

... sounds flawless and works equally well. [...] The claimed <140db probably holds true because this design sounds cleaner and smoother than anything ive built and that includes single opamp setups and well known discretes.

Click to expand...

bloqhed said:

This amp is fantastic, I've been listening away and taking notes for a better review, spent a few hours last night playing games with it, worked wonderfully. It really blows all of my other headphone amps and line amps out of the water. The clarity is surreal.

Click to expand...

Last night compared Omicron with my composite LT1210 based headamp. At first, it seemed that the LT1210 sounds softer and more beautiful, but after listening to Omicron for about an hour, I switched back and realized that now I want an Omicron for myself! With the same tonal balance, it gives an accurate, fast, assertive bass and better conveys space. Sounds great on good recordings.

Click to expand...

Will2226 said:

...the sound really is fantastic. [...] It's a huge step up from [...] bottlehead crack with the speedball upgrade.
The soundstage is really amazing with my hifiman cans and there's a wonderful amount of detail. Very liquid sounding and the amp just seems to do everything right. The amp runs very cold too, the case never even gets warm.

Click to expand...

jwchen119 said:

The Omicron is a fantastic headphone amp and preamp, the background is more black and bass is more deeper and punchier. Also the clarity is absolutely amazing, the vocal is no doubt much clear from the track "Mistakes from Lake Street Dive" than before.
And the crossfeed did something, especially from older track or some track that the musical instrument sounds are more biased toward the left and right channels. Toggle on the crossfeed makes the soundstage a bit wider and the sound is no more at the front but a bit lay back, more natural.

Click to expand...

I have the feeling my old Beyerdynamic DT-880S from 1984 in combination with the Omicron never sounded that good.

Click to expand...

Sounds good! [It has] no sound of its own. The resolution is there, and so is the bass. Highs and mids are very clean. I have been using it for a month, will put it in a case now.

Click to expand...

danbmellow said:

This little amp is something else. Listening last night it really started to open up after a couple of hours. Bass goes deeper than any of my other headamps. Very black background. Smooth yet detailed. I ended up listening much later than I had planned. Very musical. Definitely a keeper.

Click to expand...

ElArte said:

Easy to build and excellent.

Click to expand...

Features:

• Vanishingly low distortion: with THD and IMD better than -140dB (0.000 01% - that's only 100 parts-per-billion), Omicron is orders of magnitude more linear than other "high-performance" and "ultra-high performance" amplifiers
• Compact: Just one IC and two transistors per channel
• Inexpensive, commonly available parts (NE5532, BD139, BD140; under $40 at Mouser for the whole BOM)
• Easy through-hole construction (NEW: a smaller board with easy-to-hand-solder SMT parts has been developed, see its photo above)
• Functionally complete: One 80×110mm (60×90mm for the SMT version) board carries two amplifier channels, a sensitive DC protection for your headphones and an optional (switchable in the SMT version) cross-feed circuit, which helps create a realistic soundstage in headphones

Simplified schematic (links to the full schematic are below):

IMD 19+20kHz, 5Vpp @32ohm (see post #11 for more measurements):

Theory of operation:

• Schematic design: post #2
  • Mod: increasing input impedance: post #67 (this mod is now the stock version and part of the BOMs linked below)
• Loop gain (simulated): post #27
• Crossfeed schematic and frequency response: post #33
• DC protection: post #34
• Power supply: post #35

Measured performance:

• Distortion, clip, frequency response: post #11
• Distortion and clip for the SMT version with no heatsinks and half the quiescent current: post #109

Schematics, board outlines and other reference information:

• Through hole Omicron board
  • Schematic: post #295
  • Board outline: post #142 - includes a discussion of how to fit Omicron into 1U enclosure
  • Part list: post #155
  • Winding the output inductor: post #71
  • Mod: crossfeed switch board by @gajira: post #334
  • Mouser shared project - order all parts for this board in one click
• SMT Omicron board
  • Schematic: post #297
  • Board outline: post #299
  • Part list: post #298
  • Mouser shared project - order all parts for this board in one click
• Power supply board
  • Schematic and board outline: post #300
  • Part list: post #301
  • Mouser shared project - order all parts (except the power transformer, see post #174 for what's recommended) for this board in one click
• Assembly guide: post #225
• Choosing volume control: post #170
• Mod: running Omicron from +/-12V rails
• Opamp substitution: one, two.

Build examples:

• Post #173 - yours truly
• Post #226 - @bloqhed
• Post #287 - @ElArte - Fallout themed!
• Post #311 - @ElArte, another build
• Post #330 - @Will2226
• Post #393 - @Mulburg - in a vintage toaster!
• Post #402 - @emuffler
• Post #425 - @Mulburg, a more conservative build
• Post #479 - @jwchen119
• Post #545 - @namghiwook

Hi - The Undearm Incident here.
Never forget

Hiya, I'm joining this site in an attempt to learn how to fully fix my beloved NAD 7240PE and also just absorb more knowledge on audio amps in general 🙂

I am new to this site. From Australia. I have signed up to talk with audio professionals about live PA systems. I have built a 20hz tuned tapped horn, and a FLH line array kick bin for drum and bass/ house rave parties. I currently have an event startup for rave parties within my state. I am also a software engineer and have some ideas I'll be developing over the next few years. Id love to chat with individuals and share ideas I have.

Hi All,

Im a hifi enthusiast from China with limited DIY experience.

I’m from Montana and I’m here because I have a unique Rockford fosgate amp that nobody locally appreciates and so I’ve been having issues selling it for even half what it goes for. It’s a vintage t1000bd from what I can tell it’s a 25 to life edition and it works with no issues. Any help pointing me in the right direction would be neat oh and I’m looking to get somewhere between 3-500 out of it.

Hello,

i am embarked on my first DSP/Amp trial and ran into some issues regarding the gain structure with this board. While programming and measuring it with REW i got the board very easily into clipping (REW output measured at 1.5 Volts Output) without getting even full power on the outputs of the board (was not trying to anyway). So my question in general is, does someone have/had experience with tinysine boards and is able to tell, how to approach this whole topping of using an analog input without getting it into clipping/distortion whilst getting maximum output possible?
There are some dip switches on the board which i did not even touch and i am running it with a propper 36 Volts power supply.
Would be glad to getting pointed into some directions how to avoid clipping with the analog inputs!

Greets Swany

Hi.
I got the MF-A1 for repair.
Someone had tried to repair the beast before and has done some strange stuff.
I have tried to replace all suspect parts.
One side of output transistors were dead.

So now after replacing and recapping, the amp doesn´t work.
I have about 400mV on the outputs and my output transistors don´t work and are not turned on.
Output transistors are healthy and all other transistors too.
Anybody have an idea?
looks like I am missing something but I can´t figure it out...

Thx.

This is a new thread started from a rando post here: https://www.diyaudio.com/community/threads/headshakes-far-field-3way.382393/post-7434715

I've made a 3" ETON + t25b box before and this will be a reworking of the same setup. I like the idea of being able to swap out the HF/MF boxes.

The Seas L26ROY is in a PartsExpress box. It is by chance that it fits without any adjustment.

I will measure the drivers next and make an ideal sim to reference along the way.

The JA-0801 is in a foam baffle for now. I used some Loctite power grab and some wood skewers to hold the stand together. Metal screws are holding the driver down.



The hypex FA123 can be seen at the bottom of the image.

The tweeter will be picked later.

A translated info sheet about the dome:

I'm not really trying to transform the 'pi. I just to make it store and play music. I have the RPi 4 with 8gb ram. Is there any downsides to using it as a media player? The major upside for me is space. I'm using a big clunky PC in a ATX mid tower that is hooked up to my JVC Audio/receiver/dac/amp now. I'd really like to clean that area up nice and neat. I'd like to hear some dos/donts from people who are using one. I'm not looking to make chicken salad from chicken s**t but I would like a good sounding system. TIA

Hello,
You can make an offer !

I have a Nikko Beta II preamp (the D-TYPE) that has too much gain for modern sources.
Is there any way to decrease its gain by some 15dB?
Service manual attached.
Any input is appreciated!

Good morning,
I have an opamp in my hands, the OP27, possibly to be used as a reference for a regulator circuit. I later realized from the datasheet that an example circuit is also a phono stage in a preamp.
I was wondering out of curiosity if anyone has ever used it like this, and if it sounds good despite being a rather obsolete component. Thank you

Having just built a LM3886 chip amp and finding it too clean, I'm looking to add some tube warmness. I don't need any gain in a preamp, but a buffer with a cathode follower would probably be too clean. I need a grounded cathode stage. I whipped this up:



It seems to work on the bench, 2V P-P in, 2V P-P out. However, I have a very janky benchtop SMPS, and there's a lot of noise on the scope so I can't really measure anything. Is this thing a good idea, or an abomination? I would think the amount of feedback would squash a lot of the harmonic distortion. Should I go with a voltage divider at the input and AC couple the cathode follower without the feedback? Thanks, all.

Good Morning Everyone. I am cleaning out some of my Raw drivers that has never developed into projects I wanted to get done. So I have the following Drivers
for sale.They have never been used and are in a non smoke environment. They have been stored in a controlled environment and it never gets to hot or cold. They are in their original boxes. I will only ship to the 48 United States. I have the following for Drivers for sale. I will be moving into a smaller house Eventually and am going to get rid of everything I don’t use or needed anymore. Spring cleaning.

Mark Audio Drivers.

💥(Updates)1.MAOP 11- Driver’s. Original cost $589.00 a pair. Am asking $400. 00 for the pair . . You pay for shipping.

Sold/ 2.MAOP-5 Driver’s. Original Cost $277.00 a pair. Asking $200.00 you pay for shipping.


2. Puvia Seven HD in the gold color. Original cost $99.40 a pair. Am asking $60.00 a pair you pay shipping

Fostex Full Range driver.

1. FE126E speakers. Am asking a $100.00 A pair. You pay For shipping. New

2.FE126NV speaker. Original cost $140.00 a pair.New Asking $110.00you pay for Shipping.

(Updated)A. Dayton Audios RS125-4 5 inch reference 4 ohm speakers brand new. Cost per. Driver is $44.98. Asking $60.00 and you play for shipping.

Sold/ B. I have a pair of Vifa/ Peerless Ring tweeters the 4 ohm version. Model XT25SC90-04. $21.29 each. Asking 30.00 a pair you pay shipping .(Given away with Fostex speakers).

Sold/ C. I have some paper cone tweeters from Parts Express as a buy out. I think 4 of them at O.68 cents each. (Given away with Fostex Speakers).

I would like to sell for local pick up unless someone is willing to pay for shipping?
For these items listed below.

1. CHN-50P Driver’S. Original cost $40.00 a pair plus shipping was around $14.00. Am asking $25.00 a pair. You pay for shipping.

2.Auible Physics 2” inch speakers. (Newark Company and use to me MCM Electronics). Cost $22.40 each so $44.80 is the total cost plus $15.00 Shipping. So I would like to get $20.00 for the set. You pay shipping.

(Updated price)1. Used Am for sale. Dayton Audios
APA102 BT.Class D amplifier blue tooth. Cost. $184.98 I’m asking $80.00 and I will throw in a nice pair of Studio Master speakers for free. Local Pick up. Speakers

Speaker boxes for sale$

(Updated).A. Frugal Horn XL speaker boxes for sale. I have new Dayton Audio Binding post and Wire for these speakers. Pictures added now. Make me an offer for these boxes.

I can send pictures of speakers you are looking for or interested in. You can e mail me at
Jmboo1922@gmail.com with any questions and offers if you think it’s reasonable? Thanks Jeff

Sold ( Thank You) but, wasn’t in the selling post. Fostex FF166K ENAbled Drivers From planet 10 Hi-Fi.

Sold (Thank you) But, Wasn’t on this selling post. RCA ends. Sold. I have no more left of this item.

There's been a few threads about THD and its pros and cons and they always devolve into philosophical discussions.

So what about IMD (InterModulation Distortion)? I came across an article by Nelson Pass where he argues that it's a much bigger problem than THD and I agree with him, since IMD is a non-musical distortion. As we all know, all musical instrument produce harmonics, so harmonic distortion blends into the music, whereas IMD is going to be "off key".

I did a crude measurement of the IMD using the SMPTE method on my latest build. It came out to about 0.02% on a resistive load and slightly higher on a speaker. I think it was at around 5W. Is that good? Should I be worried? How do you mitigate IMD? Does a high OLG increase the risk of IMD? I know that Pass argues that you should get rid of the feedback altogether, but that opens a whole new can of worms.

I'm here to learn from you smarties. 😀 (And comments like "Don't measure, just listen" aren't useful. I want to understand the theory)

Good evening, I wanted to share my silly project about making two speakers from stuff I had lying around / was gifted to me
All the information relative to this are well written and illustrated on my blog https://www.mimifactory.com/, otherwise this post would've become too long.

A friend gifted me some old car speakers, instead of throwing them away. Plus I got some broken panasonic speakers that I had laying around for a while.
It was quite simple taking the plastic cover away, but then i realized there was no hole for the tweeter and there were two big open slots, that I had to cover if I wanted to make an enclosed loudspeaker.
I drilled a hole with a hole saw but it was too big so I had to 3D print a gasket lol
And make two wood pieces by hand to fill the two big slots.
Capacitor in series with the small speaker = high pass filter kinda
Disconnected central coil from second speaker otherwise I had too many highs

Glued everything, filled with silicone, covered the outer silver parts with some wood grain texture adhesive, and then made a front cover mesh from unused wood and old cloth.
I am currently using them with the subwoofer unit of a LM1875 based 2.1 sound system that had its satellites missing.
I wouldn’t call this Hi-Fi, but it’s pleasant enough to allow me to not always use my headphones and have my hair always messy xD
Great for youtube, videocalls, etc. Basically free as well

Hey everyone, got a JL Audio 500/1 that i disassembled to paint the heatsinks, unfortunately when reassembling i forgot to put insulator between output mosfets and the heatsink. when powering up i got green light, then low load warning light and smoke, i quickly disconnected power supply. upon first inspection i got one of output fets fried and 5 power supply transistors shorted. power supply gate resistors all measure about 47 ohm. any chance i can fix the thing just just using my soldering skills and a multimeter? i dont have oscilloscope on hand, any help would be appreciated.
Best regards

You will have seen that I'm pleased with my ER18RNX/27TDFC MTMs, so why a possible project?

It started when Mark (Islandpink) told me of his very successful speaker, Purify 6.5 inch with Satori beryllium in a TM reflex box; I know Mark and trust his judgement highly, so I know this is an exceptionally good speaker.
I need more sensitivity so I was wondering how good a MTM might be with these drivers.

Fun project?
I like what I have. The usual questions about an upgrade:
What don't you like about the present speakers?
What do you think could be improved?
What kind of change are you looking for?
My answers are pretty much nothing to all. So the project is a bit of a risk, in that I might find no substantial difference, or I might not like the differences. So I'd do it as a fun project,, for the sake of trying something (possibly) different; also I need to keep active for health reasons and a nice bit of DIY work is a good thing.

Research into the Purifi also suggested that Seas W18NX-003 nextel driver is of a similarly high quality, and this is often used with Seas Crescendo tweeter to good effect; yes, I know that tweeter is said to be overpriced, but if it's kind of similar to 27TDFC but usefully better it could suit me very well.

I know there are lots of good drivers out there, but the ER18RNX is excellent so I think only the above woofers are likely to be better.

The WAF factor remains the same, so size is limited to about 40ins high, 8 inches wide (perhaps 8.5), 12 inches deep (perhaps 13); MTM to get the cone area I need for SET amp.

2 choices so far.
Seas W18nx003, Crescendo tweeter; would give me very much what I have, but hopefully somewhat improved, little risk, not a major gain. Fairly easy to design and develop a crossover. Safe option, but less gain?

Purifi PTT6.5W08-NFA-01 (the higher sensitivity one), Satori beryllium; looks to give exceptional transparency, very good sound generally, likely more to gain but higher risk. Crossover could be awkward. Some people find the need for corrections to be applied; Dennis Murphy reckons it's harder to work with than most, may need 4th order crossover and I'm way out of my depth here!
However, these drivers are used in his Salk Bepure 2 in a 2 way TMM, and reports about this speaker are amazingly good, highly tempting. This, and Mark's info, are tempting me to have a go with these drivers.
If so, I'll need to do a lot of research into crossovers and will definitely need help here.

I think both would be excellent speakers.

Yes, I know the SEAS drivers would fit the existing cabinet. The problem is, I'd find it hard to evaluate the results, I really need both at the same time. But it's something to consider for the future.

If I go ahead, it won't be just yet, possibly about May time.

Any comments welcomed.

Looking for opinions. I'm a new owner of a Denafrips T2 DAC. Interesting piece, what is also interesting is their choice of WIMA caps. MKS from what I can tell are used in the filtering section, and I think FKP on the output. I've had mixed to poor results with WIMA polyester in the past, maybe in the filter section they might be ok, augment/bypass the electrolytic bank, but on the output and/or coupling the DAC resistor ladder, I would have chosen different if I were designing maybe.

Interested in opinions. I was looking at some Charcroft Audio Silver Mica as a possible FKP replacement, fitting MKP will be tough and wouldn't want to make a mess of it visually. Some polys in the filter section would have been nice, what are the thoughts on this? It's as good as it gets with WIMA MKS/FKP?

Some might remember my proof of concept using CDSP as a preamp. My initial tests sparked this DIY Amp project. I thought it would take some time but not this long! I wasn't even sure it would work but since its playing right now I thought I would share this build and my experiences from it. It will take several posts to cover it all so I thought I break it down into the following topics:

• Background
• Concept and Design
• Hardware Selection
• Fabrication
• RPi 2040 Pico and Controls
• HiFiBerry DAC+ ADC and UR23
• RPi Zero 2 W and CamillaDSP
• Final Thoughts

The background is already more or less covered by my proof of concept post. I will post the rest in this thread as soon as I get the time to put each piece together. Until then, a couple of images of the final amplifier, front, back and besides my custom built TD-115.

I just uploaded the best Rock songs from my Collaborations albums. Here's the link.
Login to view embedded media

Been way too long and missing many wonderful things happen in the forum
to busy sorry to say .
Most of you know that i currently construct P3A and allready produced 5231 different PCB implementing mods and different styles .
2026 will be 20 years ( man time flyies ) that i am doing that .....

So since i am having a brake from too much work ( had a really rough last year concidering volume of work ) i am willing to construct once more but this time with regulated rails or capacitance multiplier ....

Quad did in the past , Naim did in the past and soon (since classAB is a dead end ) we will see one of the big names of hi end comming with one machine ( range 50K ) that will be a typical hi end class AB ( includes extreme enclosure style and loads of transistors ) but this time with IGBT regulated rails .

Question is that if anyone thinks that is going to be any audible benefit from that ?
Question is that if this benefit will apply from low listening level till clip ?
Question is regulated rails or capacitance multiplier and why ?

My only previous expirience was with QUAD wich the all thing was single rail, capacitor coupled, sorry excuse of amplifier circuit .
BUT !!, people that used them actually as pro amps in small bars said that they sound very good , amplifier is indestructable and impossible to destroy a speaker with it ... ( probably this has not much to do with regulated rails , but mostly because is capacitor coupled )

Place your comments please
i will be more than happy to listen

thank you

hi, I'm making a stabilized power supply for tube filaments, it's a line + phono preamp.
I'm undecided whether to rectify with a mosfet bridge (lt4320 + mosfet in attached photo) or use 4 sic to220 diodes.
Which solution is less noisy? After the bridge and cap there is a lm350k or lm338k.
Thanks

I have a technical manual on guitar electronics entitled "Electric-Guitar Data and Analog Circuit Collection".
It's totally free and contains lots of information not normally found in design-build books.
Electronics techs and engineers are welcome to point out any errors I may have made. Post here or email me. hkurtrichter@gmail.com
Here's the link. Onsite click "File Share" at upper left to access PDF files with various sections of the book, and other information.
https://hkurtrichter5.wixsite.com/electric-guitar-data

Hi, I have this Rega Elicit R which was bought brand new and was working ok. However, after a year of low use it started having this problem of going silent with a click following fifteen to twenty minutes of music play. If I shutdown the amp and turn it back on after a few minutes, the amp would play but again become silent with a click after a few songs.

From the beginning the unit would run pretty hot, maybe some part inside has become weak. I am currently in a country where there is no Rega service center. Let me know if anyone has any idea about what is wrong with the Amp and how to get it fixed.

Thanks.

... only that this time it's me and not another new forum member.

So, let me introduce me briefly. I'm a tinkerer out of Germany (but I do like to pretend to be out of Palau because of .... reasons) and long story short: In the last months I've switched to a low budget CLASS-D amplifier setup (Fosi Audio V3 stereo & SMSL SU-1 as a DAC) ... but as this setup won't allow me to hook up my turntable (Refurbished & upgraded Metz Mecasound TX-4963) and I still have two Marantz power amplifiers in my possession. (Marantz PM4200 & Marantz PM-35 MK.II) I simply had the idea to repurpose the old amplifiers.

As it turns out, the Marantz PM-35 MK.II has several modular PCBs instead of one all-in one PCB ... I'm currently chasing the idea to strip down the Marantz PM-35 MK.II, removing it's original PSU & power amplification board and converting it to a preamplifier or better said a input source selector & phono stage, rehousing it's guts into a smaller chassis. Instead of just buying another source selector & phono preamp (Which would be convenient, indeed. But that won't satisfy the little tinkerer inside of me.)

So my main intention to post here, is to get some help in understanding the schematics of that amplifier (available here) or at least an educated opinion if my idea is practical or does require more effort than I actually anticipate. At least with the schematics I'm currently out of my comfort zone, and therefore I'll need some advice.

Therefore, I'll open another, dedicated thread to this project. Unless someone convinces me that it's a bad idea to repurpose that old amplifier with it's MM/MC capable phono stage.

So far for now, enjoy your weekend ! It's a beautiful and sunny day where I'm at and I hope it's the same at your location !

Company Background : Sun Valley Co., Ltd. [100% subsidiary of Toyota Industries Corporation]
Product specification
SV-S1628D Kit $1700.00
SV-S1628D 4 X VCAP ODAM installed - Made and Assembled in Japan $2,550.00

Type: 845/211 Single power amplifier
Input: Line 1 end with volume
Wiring specification: Hand wiring (power supply
part, BIAS adjuster, hum balancer is a circuit board)
SP impedance: 8Ω (4Ω or 16Ω setting is also available)
Vacuum tube: 845 or 211×2, 12BH7A×2, 12AU7×2
(*vacuum tubes are sold separately)
Rated output: more than 845/16W+16W
more than 211/7.5W+7.5W (8Ω, THD: 10%)
Frequency characteristic: 15Hz~60kHz(1W/8Ω/-3dB)
Gain: 845/25dB, 211/26dB (at 8Ω)
Size: W410xD275xH240(mm)
*including height of vacuum tube. No cage/cover.
Weight 15KG

Victor,

Some initial impressions….
The Sun Valley 211/845 amp is an elegant and beautifully designed audio component.
There are many things which are immediately apparent:
The materials are excellent, the finish of the Chassis is perfect and the coating is unusual, refined and almost indestructible. Very Nice.

This is s kit which has clearly gone through years of refinement and focus to obtain the highest level of performance. The circuits are designed with elegance and performance with dozens of notable features:
1. All of the passive components are very well specified and uniquely employed to provide the highest performance and durability. For example, the power supply employs very closely matched metal resistors for precis voltages while the audio path specifies carbon resistors, favored by manty including myself, for the audio path.
2. Extremely high quality multi strand internally tinned wire is supplied at various gauges optimized for the power and audio circuits.
3. The power transformer and filament filter/power supply design is VERY robust and can supply any 211/845 with stable well filtered power.
4. The main power supply board is designed to provide exceptional stability and filtration and separately address Blow voltage standby, and fixed bias reference voltages…very nice.
This build will be very different from anyone solely familiar with pre-printed circuit boards and step by step check box style instructions. The documentation is quite adequate, very precise and compact delivering all of the required information and guidelines BUT it is very important that the builder has noted all of the specifications and subcomponent relationships prior to the build… i.e. Know what the designers intended, why the approach the construction as they do and pay attention to the details.

Going through the instruction for the first few pages I made a few illustrative notes.

1. Note the sequence for construction and you will begin to get a feel for the relationship among the sub-assemblies and why, in many cases the parts specification is very specific.
2. The Parts list on page 6, describes not only the individual parts, but the subassemblies for which they were provided. Unlike many manufactures, Sun Valley does not package their components separately for each sub-assembly but has grouped them by component type. Thus for the Bias board the circuit board, potentiometers, connection block and resistors are all packaged in different locations but carefully packaged and verified by quality control (you will find an inspection sheet in the packaging to assure you receive all that is required. .
3. Note that you must know how components are coded, where they go or carefully follow the specifications on the parts index (pages 5-6) Sun valley does not print component values on the circuit boards (but does specify part designation relative to the parts list and schematic) and you need to attend to assuring that you employ the correct value, capacity and type of component. Resistor packs for example contain the resistors for several sub-assemblies in various wattages).
4. Mechanical assembly employs very high quality hardware with the capacity to make small adjustments to account for manufacturing variability in parts so you can obtain a perfect and symmetrical build. For example, there is just enough play in the M3 securing hardware for the tube sockets and bias boards to allow alignment of these assemblies in the exact center of the chassis holes for a perfect build and very attractive final product.








You are correct, the sound is incredible. Very beautiful design, excellent quality components; I made a few upgrades and small changes but basically and Very Well Designed.
Great and very specific guidelines for initial check and all measurements were within 3% of the reference voltages.
The sound is incredible and the power supply design, allowing a full warm up prior to applying B+ is exceptional.
I would love to comment on the noise floor... but I could not find any noise!!
This is a very quiet and refined component


"This was an interesting build. This amp is best built from the schematic with reference to the diagrams for component locations and wire routing suggestions ( I modified some of these to minimize hum). This amp has an awesome powers supply and with high quality components offers great flexibility for refinement. "

Building the F5 Turbo v2

This is the "in-progress" thread for the official build guide of the F5Turbo. This is not the final guide.

I am building a V2, with 2 outputs per side, source diodes, and no cascode. DIYaudio store PCB are being used and it will all go into a 5U 400mm "BIG Amp Chassis"

The Firstwatt F5 Turbo article from Nelson Pass, in case you haven't seen it - www.firstwatt.com/pdf/art_f5_turbo.pdf

Anyway, on to the build. 🙂


The Chassis in the shipping box and the PCB.


While we are at it, here is a good photo of the Front-end board


And here are the output boards. The component numbering on all these boards don't quite match up with the schematic, that will need to be clarified in the guide. In the time being, a bit of logic and inspection will let you figure it out.


A large transformer. 🙂



Building the PSU -


Components - PCB, Caps, resistors, thermal shutoff, inrush limiter, line cap, ground loop breaker, rectifier diodes. Not shown are rail LEDs, bleeder resistors.
Why 2 PCB? to hold the (16) 10,000uf 50v capacitors. 🙂


We will only need one Bridge PCB, and the rest can be cut off the boards.


The PSU will be built on the 'DIY friendly' baseplate, shown here with some of the chassis hardware.


The first PCB will hold only caps and the filter resistors. But there is only room for eight, and the board holds fourteen…


So a bit of stacking is required.




The other board will have the LEDs and bleeders. Please note that the resistor pads must be jumpered.


Testing the LEDs with a bench PSU


The 2 PCB now stuffed. The left will have the input from the rectifier, the right will be the output to the amp.


The other side of the PCBs


Looking down at the first PCB


Looking at the second. Again, please note the jumpers where there are the resistors.

Good evening, I was looking for some information, in particular if anyone ever created a 3D model for making a custom component in EasyEDA.
I would like to know the 3D/CAD program best suited for this.
I know how to use Blender3D quite well but I have no idea if it's possible to later on import it into EasyEDA easily, one would think that solidworks/autodesk fusion would be more suited for this. Did anyone ever try?

Regards.

Although the regulation circuit is physically connected to the incoming mains, it is disconnected electrically. A monitoring circuit detects the portion of the sine wave that is charging the first of a pair of electrolytic capacitors. Once this first capacitor is fully charged, the diode bridge rectifier turns off and a mosfet switching circuit transfers the charge from the first cap to the second. This cycle is repeated continuously.

Output voltage: -0V - +22Vdc, 0V - -22Vdc

• Output current: +/- 0.5 amps dc
• Mains: 3 Pin IEC moulded (socket on rear)
• Mains Voltage: 230Vac