Hi,
while investigating my stashes I found these three devices that I had pulled from 1970ies equipment a long time ago. The designation of the left handed one is barely visible, but clearly shows INTERSIL as the manufacturer. The one in the middle and the right handed ones show AN 122 as the designator. They've got six pins, arranged in two groups of three each. Searching through the WWW didn't help to define them, most probably 'cause they're obsolete for a very long time. Does anyone know what I have here?
Best regards!

Dear all,

this is my first post here. Welcome everybody 🙂

I recently bought a Little Bear P5-1 preamp and was not happy with it (due to several reasons like cheap components, hum, power supply operated outside its specifications etc.).

So I thought that I will build my own "Big Bear" with the tubes from the Little Bear, which are chinese 6J1 (compatible types: 5654, 6AK5, EF95).

I already build the power supply, which provides +- 32V (-> 64V) and +12V for the heaters (DC -> please no discussion about that, I want it like this 🙂).

I drew a 10k load line in the "triode connected plate characteristics" in a graph of a 5654 tube (this one: http://6bm8-lab.fr/phpBB/download/file.php?id=41 which is from the Raytheon Manufacturing Company datasheet). The line goes from ~64V to ~6.4 mA.

I want the operating point to be at 1.8mA on the -1V grid line. So the cathode bias resistor should be 1V/1.8mA = 556 Ohm.

I started to play with the tubes on a breadboard building a "common cathode" circuit (the tube is connected as triode). The circuit is like this:

- 10k anode resistor connected to +32V
- 100k g1 (grid) resistor connected to -32V
- g2 connected to anode
- g3 is internally connected to cathode
- for my experiments I connected the cathode in various ways:
1. directly to -32V
2. with a 470 Ohm resistor to -32V
3. with a 1K resistor to -32V

If the cathode is directly connected to -32V then I get a anode plate voltage of ~38V and a current through the anode resistor of 2.6mA.

With a 470 Ohm resistor, I measured 0.75V across this resistor which corresponds to 1.6mA current through it.

With a 1k resistor I measured 1.1V and 1.1mA (52.9V at anode -> 0.95mA through the anode resistor).

-> So with increasing cathode resistor the voltage drop gets higher and the current lower. At 1.8mA I would have less than 0.75V and at 1V, I would have more than 0.95mA but less than 1.6mA (I guess around ~1.1mA).

First question: With the latter measurement I get approx. my -1V bias, but I was wondering why is the resistor value so far away from the theoretically calculated 556 Ohm? Further, ~1.8mA should flow through the plate, but I only calculated 0.95mA. This seems too far away from the datasheet.
BTW: I tried three different 6J1 tubes with similar results.

Second question: Should I set the bias such that a current according to the datasheet (1.8mA) is flowing to set my desired operating point or such that there is a certain voltage drop (-1V) at the cathode resistor? In any case if I cannot rely on the datasheet and the calculated resistor, then I have to use a pot and adjust it to my desired bias, right?

Third question: In the datasheet is written G2 and G3 connected to plate. How is this possible? The tube has an internal connection from G3 to the cathode. How can it be connected to plate without creating a short circuit?

Sorry for these "stupid" questions. Hope that someone can answer my questions.

Thanks!

Klaus

I have two transformers salvaged from broken amplifiers. I have plans to build some Chinese kit knockoffs. Building a dual mono with no plans on any form of bridging. One is 27-0-27 and the other is 30-0-30 according to my meter when connected to the mains. I was wondering if I should use some diodes to lower the voltage of the higher to get it in the same level as the other one. Like a second bridge rectifier in series. Don’t think it has to be perfect. Looking for better ideas or confirmation that my idea is ok.

Thanks.

Hello all
I picked up a Sunfire Theater Grand TGR-401 that needs service. Plugged in, power off the receiver makes a horrible vibrating/buzzing sound. Based on where I think the sound is coming from it is a speaker output relay. If anyone has experienced something similar? Confirmation would help before taking things apart. Flannery does not work on 401's as they were released after his departure from Sunfire.
Thank you

Hey folks!

I've seen several great ABX box projects on here already, but not one which was quite what I was looking for, so I thought I'd make my own, and make the design available as open source.

I thought I'd post the process along the way here in case any good feedback pops up 😀

Goals:

• Switching headphone-level signals
• Relatively inexpensive
• 3.5mm TRS jack inputs / output
• Simple push-button operation
• LEDs for status indication
• Operate from 9V battery
• Draw power only while a button is pressed (good battery life)
• Latching relays
• PCB design and Arduino firmware published on github (MIT license)
• Gerber files published for public use (order your own PCB's)
• Accessible to everyone: through-hole / easy to solder parts, Arduino Nano as drop-in processor, easy to program via USB.
• KISS!

Haven't thought too much about case options, but it will likely be a hammond cast aluminum stop box, or an aluminum extrusion, possibly with PCB endplates.

Non-goals:

• Switching amp-level / speaker-level signals
• "Money is no object" components / design

Functional description

• Physical inputs X and Y are mapped to conceptual inputs A and B, but this mapping is hidden from the user.
• User interface: 3 buttons (Re-roll, Switch, Reveal) and 4 LED's (X, Y, A, B).
• Each momentary button connects power to the circuit / Arduino. Power is drawn from the battery only while a button is depressed.
• Each button also connects power to a unique Arduino pin which identifies the function to the Arduino (8V_REROLL, 8V_REVEAL, 8V_SWITCH).
• "Re-roll" button: randomly decide a new X/Y to A/B mapping (stored in EEPROM), disconnect the output relay, switch the input and dummy relays several times in a manner which maintains the secrecy of the mapping, reconnect the output relay, illuminate the initial selection ("A") LED (which remains lit until the button is released).
• "Switch" button: switch from input A to input B or vice versa, then illuminate the "A" or "B" LED (which remains lit until the button is released). The switch selection is stored in EEPROM.
• "Reveal" button: A pair of LED's is illuminated which reveals the secret mapping to the user (one of A&X, A&Y, B&X, or B&Y).

Relay operation

• Left, Right and Return signal lines each have two relays in series
• The output relay is disconnected first,
• ...then the input relay is switched,
• ...then the output relay is reconnected.

I have a basic schematic drawn up (attached), and I thought I'd post here before drawing up the PCB, in case anyone has any good suggestions! 😉

How to diy a DAB radio tunner?

I am trying to diagnose a persistent but intermittent problem in the right channel that drops out. What should the voltage be between C11 and R24? I measure some voltage on the channel that works, but none whatsoever on the right channel. All the voltages on the test points in the Fig. 5 schematic are correct and moving upstream from C11 I also don't find any differences. The difference appears at C11 and R24. Thanks.

I would like to build a portable boombox with components I have on hand and am looking for pointers and suggestions.

I am a farmer and our farm had a big aiwa bluetooth speaker that played loud until it didn't. I have a bunch of hamfisted farm hands and want to build a portable speaker that can play loud and last a full day on a charge. I intend to mount this box on a stripped pressure washer cart. would be easy to mount a passive radiator in the down firing position.

I have

Soundstream D100 Amp
Soundstream D60 amp
2ea Dayton Dc160-8 6.5" woofers
2ea Tang Band 1320sj 4" drivers also 8 ohm
2 Dayton DC28F-8 1 1/8" silk tweeters

I like the idea of adding a passive radiator, but not familiar with which product. I like the idea of adding an active crossover so as to simplify the number of components stuffed into he box. I figure the tweeters could be dropped with minimal affect on the sound since the TB's play so nicely up high. A 16" by 21" box will fit nicely on the deck of the sprayer frame and I can go as high as needed upto 30".

I am open to using a head unit or a simple blue tooth receiver. I am unfamiliar with what battery and charger I should be looking for this project.

I am an experienced woodworker cabinet maker, have a full shop. I have wired 3phase machines and micro power controls, audio I am very inexperienced outside attending directed electronics snake pit course some 15 years ago.

All feedback is appreciated.

OK, huge turn on thump due to active crossovers being single rail power and 10uF coupling caps. Amp does not have a muting relay. I know the obvious solution is to add a relay either to the amp output or preamp output.

But, is it a reasonable approach to reduce the issue to start with by carefully selecting the output coupling cap?

For instance, my sub plate is 20K input. So rather than the 10uF electrolytic, I could drop in a 1uF giving a 8 Hz first order filter and 1/10th the DC energy stored. Same token on my main amp, 33K in, so a .22uF gives me a 20 Hz roll off for way less DC charge. ( Plus removing electrolytics from the path which is trivial but basically good)

Somewhere; Self, Cordell, Didden, Pass, someone much smarter than I had a reason not do do so, but I can't find the reference.

Hi,
I have an issue with a repair,
I been told the amp works pretty good at cold winter days and not very good at summertime.
The issue is that it after a while of playing it cuts into protect, then starts working again, to be in protect again, and it goes faster frequency after the first time.
its been checked by a man referred from b2 to repair, without finding any fault.
I just checking if any encounter this problem before.
I was suspecting the ntc resistors but i used a heat gun and multimeter and the resistance goes down with increased heat. both side seems to be alike.
Any ide where to start ?
psu board, comparator circuit ? or bad MOSFET that heats more then others ?
best regards
Niklas.

I saw the thread
http://www.diyaudio.com/forums/powe...or-replacement-sic-rectifier.html#post5348261
and wanted to be informed of these semiconductors.

The search for "GaN transistor" in parentheses turns out with no result:
"Sorry - no matches. Please try some different terms. "

Search without parentheses is useless. But as you see in the thread title
the phrase was used in the forum. "GaN" alone will give no result either.

What is going on ? Thanks.


PS "SiC transistor" search works ..

I have a Pro Ject RPM 1.3 turntable that will be over 30' from my AV rack, and I have a Music Fidelity phono preamp that will be next to the turntable. I cannot run balanced from the turntable as the table has RCAs.

Question: I prefer to spend under $500 for a balanced preamp (I could go up a bit more). I have looked on Ebay and see a lot of clones (MBL and Levinson JC2), but I am not sure if all balanced preamps with XLR, and RCA jacks will convert the unbalanced to balanced audio( I say this because my Music Fidelity phono preamp will not convert). I also would prefer to not lose any audio quality with the preamp. Do I need to spend more, and buy a non clone preamp?

Will a passive balanced preamp be able to drive such a long run?

I would like to build an SUT for my Denon DL-103R.

According to Theanalogdept website the Cinemag CMQEE 3440A with a step-up ratio of 1:35.4 should be a very good match-up but with the Denon DL-103 [.3mV].


However, the output voltage of the 103R is 0.25mV. Will 0.05mV make a difference?

The 103R has a 14 Ohm internal impedance which is quite different to the standard 103's 40 Ohms.


Cheers,

hi guys, i need some help. i am building a power supply for a mini pc based on this mic29752 regulator. what is not clear to me is how to choose the resistance values ​​to get the desired output voltage. I would use a 15V transformer to get about 21V in to the regulator and I would like to go out with about 20V. there are infinite combinations to obtain this value, for example r1 = 1000ohm and r2 = 70ohm, but also r1 = 200ohm and r2 = 13ohm etc ... can you explain to me? thanks!

Accordi to datasheet: Vout=1,240 x (1+R1/R2)

Heard of this cable? Curious about it? It is extraordinarily good. Ignore the price. I've used it exclusively in my system for about fifteen years, which is almost all Pass electronics. Before the Gotham, I had Audioquest Lapis (then top of the line) and then cables from FMS (a legendary cable here in New England). I don't have to tell you why I switched. I recently sent some to a friend who has the best system I've ever heard (outside a store) and who has very expensive cable from a very famous name. His response: "I need more of this wire".




If that's not enough, Pass Labs used Gotham Cable to connect the two halves of their $16,500 XP-30 pre-amp when it was used in mono. I'm guessing they didn't do it to cut costs.

I have three pairs of balanced interconnects built from Gotham Audio GAC-4/1 "star quad" microphone cable and Neutrik XLR connectors that need a new home. I'm selling them for less than the price of the connectors: $10 a pair. You couldn't build them yourself for less. I have two 2ft pairs and a 3ft pair. Easy way to try out this cable and see for yourself. Then you can buy the wire and make some yourself.

Shipping should be no more than $8.30 (in the US): Small flat rate box. We can probably do it for less.

Furamn RP-8 for sale. Doubt anyone wants to ship. Local pickup is fine. Zip 17403

$15.00

Thanks

Hi all,

I've been a long time lurker and have a little experience tinkering with guitars and guitar amps, as well as building handheld Nintendo 64s and other oddball projects. Just now looking to put together a decent phono stage, amp, speaker setup and figured it time to join the forum.

I'll post my projects as they come along, just making an introduction here and thanks in advance to the helpful forum members.

Brett

Hi all.
Does anyone have a service manual for the alpine pdx 4150 (4x 150rms)
Had mine burn up and can not read components as a result so a scematic will be needed
Thanks guys 😊

I've had this receiver since my high school days... it has been my trusty workhorse for over 30 years, and now I've gone and done something I don't know how to undo!

Recently I picked up a Polk Audio PSW505 powered subwoofer. Since this receiver has no "sub-out" connection in back but does have A and speaker B outputs, I tried hooking up the sub using the two channel speaker option, per the sub's owner's manual (attached photo) but using "front" speakers only, since I don't have rear speakers.

After setting this up, the stereo started shutting itself off within a few seconds of trying to play music. When I powered it on, it would shut off again.

So then I disconnected the sub and went back to my earlier configuration, just using the R/L speaker A connections, and the problem persists. Only now, it shuts itself off after a few seconds of play time, then shuts back on again, etc.

What have I done to my beloved old receiver?
Any suggestions to remedy the situation?

Thanks in advance!

Rear Panel - Yamaha RX-700U Owner's Manual [Page 8] | ManualsLib

Eric

Dear all,
In most Pioneer vintage amps the idle adjustment is set by two jumper cables. If it measures too low you're supposed to cut the jumper cables. See picture for an example.


I'd like to replace these jumper cables with a trimmer to precisely adjust it. Which type of trimmer would be suitable? How many Ohms and how to solder in the leads (three leads seem to be the standard)? Thanks in advance for your advice.

Okay. So. I still haven't finished my "top caps" project, and I have a 6DY7-based hifi project waiting behind that. But I spent the last week out of town and away from my stuff, so I started noodling on the next guitar amp project.

Donor is an early 70s Bogen CHB-35A. Original tube complement is 6EU7, 12AX7, 6C4 concertina PI, and a pair of 7868s in AB1. So let's see ... five triodes and a push-pull output section ... sounds like a one-channel AB763, if I do the reverb in solid state and eschew the tremolo. I've even got a pair of matching 1x12 cabinets that came as part of the complete PA.

The basic plan is to reuse the iron, chassis, and sockets. I recently bought some 6P41S tubes, so those can go in the power amp. I've also got a bunch of 6N2Ps, which make fine 12AX7 substitutes. Add a 6AV6 to go in the 7-pin socket and we've got everything we need.

I adapted Robrob's one-channel AB763. Notable changes:

• Reverb has been replaced with a simple BTDR-2 circuit. More on that.
• Power supply is very different. The donor uses a voltage doubler and a capacitor-coupled bias supply, so I pretty much had to stick with those. The 6P41S has very low screen voltage specs, so I'm pulling them from the 1/2 B+ point on the doubler. It also needs -65V bias, dang. And I'm omitting the choke in favor of an extra RC filter.
• No tremolo.
• 6N2P for phase inversion (as opposed to 12AT7). I like the hotter sound of a 12AX7 in the PI in BF Fenders.

Other than those things, depending on your perspective, it's either a Super Reverb with diode rectification, or a Bandmaster with reverb added. The preamp is pure AB763.

About the reverb ... I found a lot of conflicting information about how best to make use of the BTDR built-in to a circuit. I took the simplest approach I could: A voltage divider to attenuate down to its 1.5V limit, an LND150 source follower to handle the low input impedance, and a voltage divider network to get the signal back to the mixer tube. HOWEVER, I know this circuit isn't right. I would appreciate any thoughts y'all might have.

I'm copping out on the 5V power supply for the reverb and using a USB wall-wart, with some additional filtering.

Anyone has
proac reference 8 signature crossover schematic??

I have proac reference 8 and I recently got seas excel 4.5in woofers.

I will install it to reference 8, so I wanna retrofit the crossover.

what is different between
proac reference 8 crossover vs. proac reference 8 signature crossover??

Any idea what to change on the crossover?

I'm looking for the service manual for Marantz portable cassette player CP130. Hope you guys could help.

Thanks

Behringer Ultra-Q Pro 5 band parametric equalizer. Excellent condition. All functions work. Nice unit. Asking $40.00 plus PayPal fees and shipping.

Looking for good used EV MC8a.

Hi everyone.

I built the circuit several times using DN2540, and tried several different ones, and I can get down to 0.3 mA. No problem. Using different JFETs as the bottom device too.

I've read many times that a cascoded depletion mosfet CCS can be problematic if the Vgs of the top device is not large enough, as it limits Vds of the bottom device, and that limitis the minimum current that can be achieved.

Was I just lucky?

I just measured about -2.5V for the top device Vgs on one of those circuits I still have around, while set for around 0.4 mA.

I'm looking to add an arduino to control my dac. I'm not worried so much about writing code as that's already done and proven to work for others. This whole platform is new to me. I can see that the initial scrpt or program is the .ino file and that will contain commands as well as references to libraries but I'm not sure how to put this altogether in Arduino IDE to upload it to the Arduino Due.


I purchased this display for the project
5"TFT Display Arduino Touch Shield w/SSD1963 Library for Mega/Due


There is a download with examples in it here
https://www.buydisplay.com/arduino/Libraries-Examples_ER-TFTM050-4.zip


I want to test the 480x272 demo. I see the ino file and have downloaded the UTFT library and added it to Arduino IDE.


Do I open the ino file in sketch then include the UTFT library and complile then upload? Or am I missing steps?

Inspired by this
The Slot Loaded Open Baffle Project Article By Nelson Pass
I am phantasizing about a floor to ceiling slot loaded open baffle using 10 Tymphany XXLS-300F50AL01-04 per side.
As a little exercise I experimented a bit with slot loading on my Beyma 15BR100 U-shaped open baffles.

Thight fit, but moveable with rubber mallet




Anyone done the same, what are your perceptions?
I conclude with Pass'...there is gain, also I would say "attack" and "faster". On the negative a bit of change in tone, the mellow and effortless of true open baffle has changed to a bit of "hollow" and yes...boxiness. The cool thing is how easy it is to experiment 🙂

Hi everyone. I got a nice deal on some speaker boxes.
For a around 15$ i got two nice beefy speaker boxes with a nice paint job and woodwork. Anyway boxes are 24 cm wide by 50 cm high and 39 cm deep and have 14.7 cm cutout for woofer ( i think it is for 6.5") and 8 cm for tweeter and 9 cm hole for flared bass reflex tube...
They are made of 18mm MDF with a decent amount of bracing and feel super solid like a solid block of concrete lol. I think that volume is around 1 ft3 or around 30l. Calculations are not 100% accurate they are just approximated.
The first driver I was thinking of was a visaton w 170 s but I don't know how it would work in 2 way... And I want a hi fi sound but this visaton driver seems like it is more aimed towards low bass rather than quality bass
Second one I looked at is really expensive one compared to visaton but it also seems like it would fit in 1 ft3 enclosure. It is a tang band w6-1721. It seems nice but that is a lot of money to waste if it doesn't work out.
I was also looking at Dayton audio drivers but they require much smaller enclosure.
I want nice warm and punchy bass and mid-range rather then muddy low bass. Sorry for the wall of text and thanks in advance.
Here is a video of one of the boxes...

speaker boxes. - YouTube

Four new/unused Tang-Band W3-881SD need to find a project. Free, you pay shipping outside of San Jose, CA area.

Unfortunately, I find very little information about Aikido, as an output stage for the DAC (directly to the power amplifier), which I would like to build in balanced version and which has an impedance < 100 Ohm at the output, so to speak in buffer function. I found a table (attached) in the Broskie documents, in which some constellations appear, which make this possible. But approximately only with 9-pin tubes. For octal tubes, which I would like to use, only the type 6AS7 is to be found (B+ 100V), which however is accompanied by a very high current (Ik 100mA).

Can anyone tell me if there is a range of values that makes it possible to use octal tubes? With: B+ of 150V, lower Ik value and Zo < 100 Ohm. Otherwise I have to start with Noval tubes. But again, I can't find any values that would meet the requirement.

Does anyone have a tip?

I bought 24 pieces of LME49720HA TO-99 from member denaudio 1,5 years ago for my upcoming active crossover. But now I decide to go with SMT opamp, so I would like to sell some of them (20 pieces).

All of the opamps are new, never been soldered or installed in circuit.
Price will be 5 USD / pieces. The items will be shipped from Germany

TI

LME49710HA (TO-99, metal can)......5USD
LME49713HA (TO-99, metal can)......5USD
LME49720HA (TO-99, metal can)......5USD
LME49990MA (8L-SOIC)..................2USD

LME49600TS (KTT)......4USD
LME49810TB (TB-15).....7USD
LME49811TB (TB-15).....7USD
LME49830TB (TB-15).....7USD
LM4702BTA (TO220-15)........7USD

LM4780TA (TO220-27).......8USD
LM4781TA (TO220-27).......8USD
LM3875TF (TO220-11).......6USD
LM4765T (TA-15A).....6USD

BurrBrown

OPA549T (60V, 8/10A POWER AMP).....7USD
OPA548T (60V, 3/5A POWER AMP).....5USD
OPA547T (60V, 500mA POWER AMP).....3USD

PGA2310PA, PGA2311P,PGA2320I, PGA4311U...( Digital valume)....4USD

All the stuff is 100% genuine, from manufacturer, looks like mostly obsolete by now. I can send it worldwide for 6€, as long it can be send as regular letter, in bubble wrap protective envelope. Payment via PayPal or bank transfer. Will also be glad to swap for something that interest me, mostly PCBs for above listed components...Make me an offer..

Regards

This thread is to discuss everything about the Feixiang FX-98s PCM2704 USB DAC, including reviews, upgrades, mods, problems, troubleshooting, etc.

The FX98s is a budget USB DAC with a Burr-Brown PCM2704 DAC, XR1075 BBE, QS7779 Virtual Surround decoder, surround, bass, treble and volume controls, straight-through line amplifier (line in to line out) and headphone amplifier - all in a compact extruded aluminium chassis with good finish and production values.

It is upgrade friendly in a few areas - electrolytics and opamps, which are generally the only things that need upgrades, if at all. The pics below show the board and a few upgrades that I performed - the only upgrades that are really required are the opamps (2x NE5532 upgraded to LT1208 and LT1364) and C8, the analog regulated voltage bypass for the PCM2704 (upgraded from Rubycon YXA to Rubycon Black Gate PK). I upgraded some additional electrolytics in the signal path to Nichicon Muse SW and Black Gate PK, though not strictly required for a first-level upgrade.

I'd like to put (mono) amp & crossover on the same PCB, and can get 4-layer boards made. Crossover uses +/-12V (regulated); Amp PSU will have a separate bridge for each (25V) rail. My idea is to use one internal layer for 0V (shared by both supplies), and the other for signal Ground. Will this work?

I am looking for a transformer for my preamp project with a roughly 380 vct secondary but with both a 5 and 6.3 windings for heaters. Right now I have a Hammond 269ex which seems to be giving me the high output I need but only has one winding for heaters. I have been unable to find any transformer with both the 5 and 6.3 that has a vct under 400v. Does this exist?

Thanks.

Hi, first post! I hope I've done this correctly (I wasn't sure how to format links, if that's a thing) and I couldn't see any threads about this already. 🙂

I've recently been gifted my father's original 1978 model Rega Planar 2 and when replacing the motor suspension belt I stripped the head of one of the screws which hold the motor in place.

I'd read [1] that I should be replacing them nylon M3 screws, so I ordered some to find out they're too small - the threads don't bite properly and the screw head does not fully cover the hole in the platter. So I ordered a set of M4 screws to find they're much too large and wont even fit in the hole.

I've messed up twice so I do another Google search and find people saying it should be a M3.5 screw [2]. However as far as I know M3.5 isn't actually a standard and there for screw options are more limited. After an eBay glance it looks like I'll have to get white flat heads or white bolts instead of the original style black philips head screws. It would annoy me if they don't match the original style but as they wont actually be visible during normal operation (only when the platter is removed) it's not the end of the world.

So before I continued Goldilocks-ing with M3.5 I thought I'd ask more knowledgable folks if I'm doing something wrong?


Can anyone confirm I should be using M3.5 or could the M3 have had a manufacturing defect (like they're actually M2.5)?

I've included an image of all the screws in question - M3, Original, M4. The original screw is in the middle and 5mm long, the replacements are 6mm long as I wanted them to be a little easier to screw in. You can see the M3 seems quite small, it does have a tighter thread pitch. The M4 and the original might have the same thread pitch, I'm not certain.


(These screws are plastic/nylon in case anyone didn't notice, if you overtighten they're meant to fail before you do damage to the motor mount)


[1] '80s Rega Planar 3 motor suspension screws | pink fish media
[2] old planar 3 refurb - motor mount screws- Vinyl Engine


Thanks for any advice! 🙂

Hello guys! New member here 🙂



I'm trying to build my own microphone AB switch. Something like this:


https://www.palmer-germany.com/en/products/signal-splitter-switcher/5114/abo
or
HotShot DM-1 - Radial Engineering



But both of them are specified only for use with dynamic microphones. I want to use it also with condenser mic but I can't figure out how to do the wiring so there are no pops because of the phantom power.


What it should have:
1 XLR input
2 XLR outputs
Should be able to be used with dynamic or condenser microphones (with phantom power)
Optional LED indicator of either channel


Is there anyone who has already tried something like this? Or someone who would be able to help me?


Any help will be much appreciated!


Thanks,
Honza.

Troels tqwt is a speaker I would love to build one day. The problem is that once you add a shipping and the drivers and tax it is way out of my price range. Are there any more affordable alternatives available for this driver?

I was also wondering if someone could explain to me how Troels tunes the enclosure to increase the sensitivity of this driver as he mentions in the link below. I've never heard of this before and I thought sensitivity was solely a product of the driver(s) design and implementation. I.e. using two drivers in an mtm to increase sensitivity.

http://www.jantzen-audio.com/download/ja8008-tw034-kit/PD_JA8008_Aug10_v3.pdf

WANTED. 46volt SMPS for Hypex UCD180 class D amp.

My implementation of the Inverse RIAA Network (IRN) for testing phono preamplifiers, based on the Andrew Russell article (November 2016, http://hifisonix.com/wordpress/wp-content/uploads/2016/12/Accurate-Inverse-RIAA.pdf). For MM and MC preamps. Surface mount resistors and capacitors (<=0.5% R, 1%C) for better than 0.025% accurate performance. Requires a signal generator with output impedance of 50 ohms or less for testing.
$30 includes shipping to CUS only.


11/16/2020 Unit is SOLD

PCB's are still available


For those who want to practice/improve surface mount parts soldering skills, I have (8) pcb’s available. Thirty eight 0805 part size resistors and capacitors are required. It’s not too difficult to do.
$5/board shipped to CUS only

PM if interested. Thanks.

Hi,

I have a soekris DAC dam1021-02 (0,2%) for sale.

The DAC works well with the DIY INHK DXIO Xmos card.

asking: € 160.-

Shipping from Germany.

Best, Andi

IMG-4630 — ImgBB

Here ow the new "Measuring LDO with passive/active notches/filter", so that we no longer hijacking the "Low-distortion Audio-range Oscillator" thread.

Administrator please move last related to this one..

In other words the measure a LDO with passive components or using active components as with OPAMP's provides several challenges in terms of

. Notch Depth
. THD & Noise added given from the parts (R/C/OPAMP's)
. Noise alternations (reduced or amplified) in any form
. Harmonic's attenuation
. May consider balanced or none balanced use

..


Hp

Well, I did not know where to post this thread, if the moderators think there is a more appropriate place they are welcome to do so! 🙂

I would like to ask this: in what frequency range does impedance matching become important in order to avoid problems?

For example, I will try to pass a 2.5MHz square (or sawtooth, fast rising or falling edge anyway) to a small capacitor (50-100pF), but with lots of volts in amplitude (50-100). So I wondered:

Let's say I use an RF transformer to step the voltage up. There are 50 ohm transformers available for that purpose. But if I was to terminate the transformer properly, I would have to waste around 50Watts of power on these terminating resistors! 50-100Vpp into 50 Ohms should be something like that.

Then I wondered, what if I just hooked the transformer up and don't match impedances. Is my frequency high enough to encounter problems? A fast (20ns) falling or rising edge might hide frequencies up into 50-100MHz, so the spectrum is broader than 2.5MHz, and that got me into thinking.

And, sadly, I can barely find clear explanations around the web about how to proper match, and when to do so (frequency etc). If anyone knows a good place about all this I would be glad!

hi, can someone help me to clarify some doubts? I wanted to know the relationship between the capacitance of the filter capacitors after a rectifier bridge and the amount of maximum current that the rectifier diodes can accept. let me explain: I know that after the bridge, if the capacitance of the capacitors is too small there is too high a ripple, if instead it is too large, you can have a peak current at ignition that is too high which could damage the bridge. so given a certain voltage, what capacity to use ... what is an acceptable ripple (1v?)? (however using a downstream regulator)

Hello everybody .
can you tell me where to find information on the volume control configuration made in relay similar to R2R configuration?
I also need a schematic to understand how it works.
bye thank you

Hi all


The product features of the Cambridge Audio Digital DacMagic Plus product says:
"Twin Wolfson 24-Bit DACs"
but do you know specifically what Wolfson DAC chips are these?



https://www.amazon.com/Cambridge-Audio-Digital-DacMagic-Universal/dp/B006LEDXOE


Thank you

Hello,

Some two years ago I built speakers and made a decision to wind inductors myself. Not the greatest speakers by any means, but they're mine.
About a month ago, they started to act weird, - the bass driver in one of the speakers started to sort of lose connection - like headphones with broken cable. After a week of this on-off issue nonsense, the other one gave up too! Thought maybe the amp is going (never doubting yourself, right?) but upon opening one of the speakers - I noticed that the inductor, which I soldered directly on the driver terminal has come off.
Funnily enough, the other speaker has the exact same issue.
So I have few ideas as to what could be the cause and hoping, anyone can rule out one or more.
1. I did a poor job of soldering the inductor to driver (If I'm allowed to say so, I know how to solder (but not too bright with electronics 😀 ), been doing it for a long time and am aware of how cold solder joints are made). But maybe the copper wire and enamel is playing a role here? I did clean it off and anything remaining should have burned off.
2. The inductor got hot enough to cause it to fail eventually.
3. My amp is pushing large current through terminals which cause excessive heat? (this is pure guess without any backing)

The inductor is 0.793mH - not sure what else is of importance, so please ask.

I did jump the gun and got a new amp working on a foolish assumption that the speakers were fine, and now I'm a bit hesitant to connect them to the new amp if I just solder back the inductors.

p.s. At the time I finished the speakers, I checked the resistance and everything looked exactly according to calculations.

Regards

Hi All,

I am about to order a pair of Hypex FA123 to implement DSP and drive my clone Klipsch La Scala.

I was planning to mount the plate on a wooden board, which in turn, would be fixed to the rear of the bass cabinet using spacers. I would likely put a closer at the top to stop the majority of settling dust getting to the plate, but leave it open on the sides and bottom to give adequate ventilation.

The manual shows that the unit has a mounting depth of 55mm, would I get away with using 60mm spacers or would that not be adequate to prove ventilation?

Thanks

Hi all


Similar to my threa about a DAC Product based on the WM8741,
I am really interested to hear a DAC Product based on the AD1862 DAC Chip.

Does a ready-made product exist and is possible for purchase (new), in 2020,
or the only option is to build one?


Thank you

I built a set of FH3 for my son last year , after that i built a set of Tabak W5-2143 for my wife's daughter ( really cool too )

as they work really great i was impressed ....
But my parents were also impressed and wanted as set of speakers

So i digged the forum for another speaker construction and decided to built a set of Victor (FE166 woden design )

Now the problem is my wife ( i know it's not a pb in fact 🙂 ) =

She says The FE166 Victor are nice and sound really good 😎

I'll go for a LB ( nearly 100% confident )
No matter WAF factor or money : What would you build ?


ps : at the moment my wife says " i love that " so no Waf issues for me 😀

I have two used Dynaudio 17W-75-8 mid-woofers and two used D28AF-8 tweeters. These have been in a cabinet in my garage for 20 years. They need a new home and hopefully a project. The 17Ws are in great shape. The D28s have experienced some abuse. Little fingers poking the dome. This shows in the pictures. Pickup in San Jose, CA area or you pay shipping.

Hello all. I am trying to put together a BOM for a 12AX7 Baxandall tone control board that I bought quite some time ago. I can figure out most of the components by reading the rather good information in the silk screening on the board, but I am not experienced enough to determine resistor wattage by "eye".

Here is a pic I found of a finished board. If anyone could help me determine wattage values of the resistors it would be a huge help to me.



What I see are "small, medium and large" - I could assume 1w, 3w and 5w respectively, but I don't want to assume.

In an attempt to fill the hole left by Antek, I have contacted Primrose of SumR about a GB for Toroids. While they are more expensive, in theory they should be of higher quality and more suited for HiFi. In an effort to get largest possible discount, We need to try to limit the VA rating of the toroids to two, maybe 3 different power levels. I was thinking 400 and 800 VA. At a quantity of 25, we get about a 12% discount, with qty of 50 bringing about a 25% discount. This is supposed to be per VA rating, but i think he make an exception if we can get the numbers up. He is willing to drop ship to locations, so there will be no added shpping cost over what is normal.
I think the best idea is to post your name and desired values and lets see where this goes.

Hello all
I have just received my kit and am starting assembly. I am inserting the input/output RCA connectors. Should I dremel around the hole for better contact ofr the earth connection ??
Cheers
Bruce , Oz

Free x-over parts from GNP Valkyrie Speakers. Free pick up or will ship at your expense. Located in Ventura CA.

Hello All!

I have a Skar RP2000.1D that I am repairing. It had all the output fets shorted and also 3 of the power supply fets shorted, along with some of the gate resistors. I removed all the FETS, and was curious if I can check the gate waveforms with the FETS removed, or if the driver IC for the power supply needs them in place to get its power.

Just trying to learn while I wait for parts to arrive!

Thanks,
Mitch

Included is a stock photo of the guts. I'm at work right now and don't have the amp near me.

Hello! for long time i haven't had any bass amp to gig but i have some parts at hand to build one, i had experience giging with a improvised 12W tube amp for rock/heavy blues with a dirty bass tone with no issues, but i need a bit more power in the range to 18-30W to play more versatily with more headroom with enough OD.

Short story, my plan is to build a Marshall 1959SLP clone with a pair of EL84 at the end fixed bias, at 450V B+... yes is kinda high but has anyone tried it before? btw the screens are on the range, at <300V and plates idle at 24mA, with those voltages the amp gives me 25W-ish (10%-ish distortion) and 30W full clipping.

I've heard some people prefer cathode bias over fixed for this tubes because at higher voltages don't sound very good nor the linearity, anyway i'll attach the circuit if you wanna check if i'm way out of spec or there is any hope.

Hi,

I searched.. hope I'm not duplicating (again)

Do you like your beer / lager with a head or full to the brim?

Does anyone have a schematic for a Danelectro model 78?

It looks to be all original. Has the two prong cord.
I didn’t plug it in.

Hello!
I'm trying to rewire this plate amp to SE mode. Since I have no clue about what I'm doing I thought I might get some help on this forum. So far I've reconnected the cables as pictured. The problem arises when connecting the RCA. There's a loud howl when powering on and the cone starts to move outwards. At that point, a second or so, I turn off the amp.

Some clues about where and what to look for is appreciated. I have a basic multi meter.




Edit: SE mode = Stereo mode

I picked up a half dozen of these at a local estate sale that I would love to use. There are a few things I need to know that isn't mentioned in the datasheet.

1. Can I use capacitor or choke input?

2. Voltage drop

3. If capacitor input is ok, then max capacitance

If anyone has used these please let me know

I have a 120mm tunnel heatsink that I'd like to give away. It's 11.5" long and supports 120mm fans. Pickup in the San Jose, CA area or you pay shipping.

Many important things happened in 1977 in the audio world.The least important one was the fact that i was born that year, obviously...

One of the most important though was that E.F Taylor came with a very interesting phono preamp who's beneffits can be scrutinized in this document found here :

https://www.keith-snook.info/wireless-world-magazine/Wireless-World-1977/Distortion%20in%20low-noise%20amplifiers.pdf


I am trully thankful to KCP for pointing me towards this design a few months ago. As i'm lazy i ignored the original schematic and i told myself that maybe nowaday's op-amps can do the job without the frontend transistors, but i wanted to use one of my preffered and easy to use riaa network which leads to some problems as the headroom srinked heavily with available modern op-amps, but i wanted a 10x headphones amplifier next to that phono preamp and that was already built for the max headroom of Bayerdynamic DT880-250 ohms version, so i couldn't get Taylor's phono preamp gain on board too due to my needed overall gain of phono preamp + headphones amp... I built two different versions, one supplied with +-21.5v based on M5220, and one supplied with +-16v based on OPA2228. Some may wanna try different op-amps.

I could tell a lot about all the things i tried with this phono preamp but some may be unimportant so i won't dive too much into it. One of the most limiting factor was that my Technics Class AA based headphones amp is supplied at +-11v and with a gain of 10x the phono preamp headroom is really problematic on dusty records, so i tried some soft clipping methods, but in the end i chose to simply clean the records and let it go...Probably my next approach will be to build a proper compressor.

The only reason why this type of phono preamp never got famous is that you need to rewire the tonearm shielding wire in usual turtables (mine was Dual 701) and attach the preamp right at the end of the tonearm's wires and shield the whole thing which i did.The supply wiring are shielded, including the ground and the shield wire itself...i know...it's crazy, but the final result is fenomenal and if you didn't try that yet it's just about time!

I had two questions that I was wondering about. First is: has anyone tried swapping coupling caps to change the sound of the amp? Its been my experince so far that driver tubes didnt make a huge change in the sound and I was wondering if swapping in more expensive coupling caps would have much of an effect or not? Second question is does anyone know how big the holes on the pcb are for c9 and c11? Im wanting to use miflex copper caps but the leads and a twisted pair of wire and are pretty large. Thanks

Hi folks!
Since I bought Altec Voice of Theatre A5 speakers, I’m trying to materealize my idea and change my 300b amp to something even more low power.
Would love to try 205d. Any ideas what circuit and OPT I should try / use?
What about recreating Yamamoto 205d amplifier?
Also, any impresions on how 205d sound vs 300b, and in general low powered amps sound is more than welcome

I recently bought an LJM capacitance multiplier (power supply filter).

The 6800 uF 63V Nichicon KG have very messy printing/sleeves.

The United Chemi Con LXZ are a value that I can not find in the datasheet. 2700 uF 63V does not seem to exist.

Are these yet more fakes?

NAGRA Jean Claude Schlup Gİft 1 - Plasma Tweeter Schematic, Pictures

Hello there , I have an suprise to you. I am communicating with nagra chief designer and he sent me two gifts. First his lab plasma tweeter pictures and schematic , other is for driving tweeter , 300b active part and driver. Second will be at tube amp section.

If you want larger scans and video , visit libgen.rs - notice for later libgen visitors , last to digit changes , look from wiki , download links 1-2 should work. Search for NAGRA.

Lets tall about how to build plasma tweeter ?

I am looking for advice how to eventually improve Yamaha AX590, AX592, AX596, AX870 and AX890 amplifiers by modding them.

All of these amplifiers have basically the same power amp structure. And having read Douglas Self’s book on audio power amplifier design, I suspect some potential benefits in modding these amplifiers. I will try to enumerate my modding candidates along the specific circuit of the AX596:

- Input differential pair: Include Q103/Q105 collectors GM degeneration resistors for improved linearity ot the input pair (along with a suitable Ic)?
- Input differential pair current source: Split R123 and add a midpoint capacitor to V+ in order to improve PSSR?
- Input differential pair current mirror: Approximately match both Q107 and Q109 and reduce the values of R113 and R115 to max. 47 Ohm ... 100 Ohm?
- Dominant pole compensation: Is performed by C105/R117/R199 at base of Q113? A Cdom between - Base of Q113 and Collector of Q115 might be a better option, along implementing an output-inclusive compensation (Self, 6th edition, Page 339)?
- VAS: Quite low Ic for Q113? Increase it to fit the best possible value? Or exchange VAS type altogether?
- VAS: Cancel/omit the (Self: cruel – sic!) open loop gain reduction which is performed by Q115 collector’s loading down to ground by R201?
- Bias voltage generator: Insert a trimmer in Q117 R network (for all AX59x, the AX870 has one)?
- Output stage drivers: Fit a parallel bypassing capacitor along FR101 in order to improve switchoff behavior of Q119A and Q119C?
- Output stage power devices: Decrease Q121A, Q121C, Q123A and Q123C emmiter resistors R111 and R135 values to 0.1Ohm instread of 0.22Ohm, in order to improve linearity of gain in the crossover region?

I use several of these AX59n, AX870 and AX890 amps for multichannel projects. And it seems, that these inexpensive mods could more or less easily be done on the printboard. But is it really worth to switch on the soldering iron in order to perform some of them? And if so, which ones? And maybe I overlook some candidate mods?

Thanks for any advice. And also thanks for an eventual link pointing to an AX890 service manual – it seems nowhere to find in the net.

YamahaAX.jpg

Hi,

I bought a used 1970s era console stereo made by fleet wood with a garand 3000 turntable in it. It sounds pretty good (to me and for my purposes: a stereo my wife will let me have in our living room), but the left/right balance seems to be drifting, and it gets more dramatic as it warms up; but even when it’s cold the balance needs to be adjusted to be centered relative to the center position on the adjustment dial.

I’m not sure what this could be. I wonder if it’s a transistor dying or if it’s a capacitor? Anyone have any thoughts or suggestions on how I could figure it out?

Hello all,
Is anyone aware of a good source of information on reading THD frequency sweep graphs so as to identify the prevalent sources of distortion in a particular solid state amplifier?



I am working on version 2.1 of a solid state amplifier board and have made distortion sweep graphs (THD, 2nd harmonic, 3rd harmonic) at various operating conditions (1W, half power, 50W full power ; 8ohm, 4 ohm load) and now am working to unpack the graph lines to discern which amplifier distortion mechanisms are dominant and need attention most.



I have worked (several times) through my copy of Douglas Self's 6th edition work on power amplifiers, but would find it helpful to review an article or chapter that lays out how to ID the various distortion sources from test data in one consolidated source. That type of information is splattered across the whole length of Self's book and I have tried to sift it out slowly.


Any tips would be appreciated.
Mike Miller

Hi everyone🙂 Straight to the question, although it has whizzer, lighter cone, low mms and mmd; there is no information about that on the manufacturer website, not even full t/s parameter and frequency graph. Is it a full range driver?
Though they(Sweton, an indian speaker manufacturer) claim to be market leader in india and overseas, i have no hesitation in saying that this claim is absolutely false.
They will even fail to compete with reputable foreign speaker brands. No chance! But currently i have no other option 🙁

Hi there! I am new here and I will try to be precise with my wording. The plan is to build a subwoofer for my home theater. It'll be the Mivox XAW 320HC

It seems that it has the possibility to add several weights to it which changes the response quite a bit. What would your choice be? I am not sure what tuning frequency would be good but I would have no problem building a 200liter enclosure!

Thank you!

My brother gave me an old crown amp. Its been sitting in a closet for many years. This monster is too heavy to lug around to gigs, so I replaced the input jacks with rca jacks, and hooked it up to my acoustat 2+ 2's. It would sound great if it wasn't about 10 dB louder from about 2 kHz on up.
Considering my Acoustats are a real brutal load in this region, I am perplexed why.
I did not replace any caps as they all looked good. And replacing the big cans would be more expensive than I want to do at this time.
Would not replacing the cans cause this.
Also, the volume pots almost all the way up does not give the volume I'd expect from my cd player.
When using my pre amp (audible illusions) I can drive it better. So I assume that p a amps have a higher input sensitivity?
Thanks,
Paul

Hi all,

Last weekend we did some measurements on a big subwoofer I designed for a friend of mine who will be using it in the LBB Maastricht (The Netherlands), an alternative place for artists, creators and skaters. I am eager to learn what the crowd on this forum has to say about it. The good AND the bad! Maybe we can improve on it with things we hadn't thought of before.

When setting out the design there was a definite constraint: it had to fit in the elevator and fit through most doors. Everything else was no issue. Well, maybe except for price of components of course. Coverage: as deep as reasonably possible without sacrificing too much sensitivity, it is intended for PA use after all.

So... I took the proven 18SW115-4 as a starting point and tried different concepts, mostly FLH and TH. I ended up with a big box that would fit in the elevator and an extender that can be added for extra extension of the usable frequency range, sacrificing a little maximum SPL.

From the looks of it, and from the kind of music that was often going to be played on the system, I suggested to add kickbins to the PA. For that we built the Cubo kick 15, loaded with the 15NLW9300-8.

In the attachments I have included the Hornresp simulations of both subwoofer designs, so with and without extender. In the following post I will include the measurements (compared to the Cubo kick for "reference").

Hi all, I have for sale a brand new BMS 18N862 (8 Ohm) 18" subwoofer driver. Purchased for a project that never got off the ground. It is brand new and never used, still in the original box. Awesome cross between Pro audio and HiFi subwoofer.

Looking for £395.00 inc. UK shipping. Will ship worldwide at cost.

Thanks for looking!

Hello everyone
My name is Walter and I'm a newbie here.
I'm planning to buy a tube amps for guitar and I don't know which is better. Marshall Origin5C or Bugera V5 Infinium.
My budget is enough to buy one of them so I really need some advice
Thank you

Hi there,

El Menco , Zenith , Silvertone
anyone know that tubes? Are they good for audio use?(double-triodes)
Thanks,

Hello All,
I am in the process of repairing/ restoring a Citation 22. The relay was clicking on and off repeatedly at random times while on, and the amp froze in protection mode. I went into a thread about the protection problem and wound up replacing the C11 33uf cap on the main board. I found this solution on an old AudioKarma thread. This got it out of protection mode, but the relay was still clicking on and off while the amp was on. I decided I would go and recap both the relay board, and the protection board. I also cleaned the contacts on the relay and the power switch. I have to say, I think the problem the whole time was just the power switch and the relay contacts oxidizing. I was very happy when I powered it on and it quietly and quickly clicked on and timed out of protect mode quickly. There was an immediate issue though, in that the status lights in the front of the amp that indicate "High Current" and "High Voltage" (these also switch the amp B/W 4ohm and 8ohm mode) are now both totally dark. The High current one used to come on right away, even before it timed out of protect. Is anyone familiar with these amps and experienced the same problem? I checked every solder joint I touched 5 times. Nothing is loose or cracked. I can't bring myself to reassemble it as it is, even though it seems to be working correctly. Anything would help.

Also, this is the first time I have posted in one of these so please go easy on me and I hope I didn't break any rules or anything. Thank you!

Hi, I would like to learn more about Class D (PWM/PDM) amps, mainly for driving headphone loads (about say less than 5W into 32 ohms in the worst case scenario). I understand only the basics of how it works. I would like to know about the difficulties and implementation of good quality Audio Class D amps (like Hypex, Icepower etc), and posting here seeking for guides. I have fairly decent idea about BJT/MOS devices, especially linear amplification, and a little bit about feedback and regulated power supplies if that helps.

I also came across a category called Fully digital Amplifiers, and I would like to learn about it as well. I think I can code my sbc to do the necessary PWM/oversampling part so I could even skip the ic that does this conversion, and only focus on the Digital to analog conversion part.

Thanks.

Hello

Is there anybody who could provide me a service manual for the pioneer C73 pre-amplifier.

I have a problem with mine.

Please use: student_fhc@web.de

Thank you very much

Kind regards
Stefan