The patents have now expired on these.... http://www.codrive.com/
I got a pair about 16 years ago and they were really special. The tech and design is unique and really sounds like an accurate midrange driver from 300Hz all the way down to low bass circa 22Hz.
I crossed them over at 300Hz to a pair of Manger drivers which are still among the fastest (step response and CSD) and the blend was seamless.
I have emailed and called Ron ( the owner) but no reply.
Has anyone got a pair of these or know a supplier/dealer who still has stock?

Thanks
A.

Does anyone here know what material exactly is used for pressing tweeter and midrange soft-domes?I assume it to be some thermoplast, such as nylon like material, but time and again silk is referred to..
And then, where to source that material?

I struggle since two weeks (hobby part time) to setup a working example of UAC1.0 USB to I2S - stereo 48kHz 16 bits on a stm32F4 discovery card (with CS43L22 CODEC).

I try to get the project developed as far as possible on existing code from ST:

• STM32CubeIDE generated code,
• The board Drivers/BSP code for the audio part.

I already know that the ST software is far from perfect, and that the implementation of Audio has been made overly complex / abstract / inconsistent. So no need to convince me of that fact: I know… I finally convinced that I understood it enough, and could leave with that.

But I don't succeed to get it working, and don't find why. The output is cracks + some part of (not correct) music. I checked with Music, and tests tracks with one stereo channel silent and the other with a 1000 Hz tone. On music, the volume on the streamer has an impact on the result:

• low volume: one channel plays something and nothing on the other
• Higher volume: more tracks and music+cracks seems to apppear on other channel

It looks like a problem with Buffer/DMA alignment. Channels mismatch, Main and Least significant bytes issues ?

I have the record and playback example working, from USB board. I normally use the same BSP and board drivers code. The I2C and CS42L22 configs are the same. The configuration of the I2S and associated DMA look the same…

In debug mode, I looked at the buffer values, with one channel active and the other with tome, and it looks correct. Pattern of values around 0 for the silent channet (0x00, 0xFF, 0x01…), and logically changing values for the tone.

I tried to modify the Sync function in usbd_audio.c to start playing the music when buffer is half filled instead of when buffer is 100% full and write pointer rollback to zero (which means that the USB is writing in the buffer just ahead of the DMA reading, seems…).

I looks at the HAL_init (mine generated from STM32CubeIDE, the other from the example), and they look similar, except for the prefetch which is enabled in my code, and is not in the ST "record and playback".

Would those symptoms trigger some thought about things to checks, or some corrections to make in the ST code that could result in that?

Help welcomed. Must be a small mistake somewhere that I fail to see…

I also have another issue (hope independent), that when I connect the USB, the board is always seen correctly by the PC (EP0 working OK), I can start music on Foobar and it plays… but EP01 is not receiving data (at least not activated). After 2-3 attempts, then it starts and I get the audio stream activate the DataOut procedure.

Best regards,

JMF11


JMF

Hi all,

I'm wanting some new speakers for my main living area in my new house.
The room is about 60m2. I will be building a Full Marty sub with an 18" UM18-22 to handle the low end.

I was going to buy some speakers and auditioned some towers on the weekend, then i auditioned a set of B&W 706 S3 2 way bookshelf speakers.
I was very impressed with them. So it got me thinking, if im going to spend $3200 AUD on a set of bookshelf speakers, surely i can DIY something myself.

I was originally a bit daunted by the thought of a 3 way tower build, but if i have a large sub handling base, a bookshelf should be a bit easier to achieve.

So firstly a couple of questions.

In such a big room, would a bookshelf keep up? I hear a lot about needing towers to fill the room etc. Does this apply in this situation?
If I'm building a 2 way bookshelf, I can focus more of the budget on high end drivers, surely i can build something to compete with the B&W?

I've built a couple of speakers in the past, have all the CNC/woodworking gear/Umik-1, so i'm well setup to actually do the building, i'll just have a lot to learn about crossovers etc in the proces, which i'm looking forward to.

I can get access to SB acoustic stuff easily and was thinking of a beryllium tweeter and a satori midwoofer. But i don't want to get ahead of myself yet.

What are your thoughts? Is a high end Bookshelf what i need?

Thanks in advance!

Hi everybody
If I take a specific design of 6SL7 driver for 71A
Fixed bias and wish to convert the 6SL7 to 6sn7 what does it takes to change it by a resistors values and capacitors
The dac that I'm talking about is the following:
https://sw1xad.co.uk/products/sw1x-dac-v/

Best regards

Months ago I received a Kind invitation from Burson Audio to try one of its discrete opamps, the ViVid V6 which I accepted.
I am used to discrete outputs since more than a decade I use a differential JFET zero FB amplifier from -ECDesigns- on several of my DACs (including one of my main) and players, and which has a smooth, refined and ellegant sound presentation whereever I use it. In fact, since then I have not played with opamps.
But recently, having upgraded my OTARI MX5050 to its highest performance I want to improve the critical Q501 equalizer amp, a JRC2043DD if I remember correctly. Unfortunatelly, the DIP8 adaptor socket there is very worn out and I had bad luck with my programmed opamp (2043; LN4562; OPA2064; Burson) comparison....I have to solve this issue ASAP.

Fortunatelly, I have here a humble but well built SD Card Player of Chinese Origin, a HiFi360.cn machine, with two SD Card slots and which has dual PCM1794 DACs (IF I remember correctly) had a passable sound in stock version and a competent Headphone out.
Of course, it did not stay in stock version for very long....I list below the upgrades which made it a very decent (as My Mom says) player...

-Reicherts Bifilar Current Baluns on AC input (varnished with Heavy Duty Varnish), and between PS caps and Voltage Regulators, both to Digital and to Analog (on PCB bottom) sections: 4 in total.
-Replacement VRegs for teddyregs, due to space cosntraints. The Heatsinks occult the former.
-Precision Clock.
-Dedicated 5V SPDIF out, to be used as transport with Elektro-optik connection to an outboard DAC.
-Many other caps, Pana FM and Rubycon Z on the output section.
-OPA2064 in class A, 3 in total: 2 for the stereo unbalanced out and one for the Headphone out, which receives the signal from the former.

The upgraded "Baluned" Regulated supply took it to a level where I could use it as only source for a whole week during my recent holidays, using my Beyerdinamic DT990 PRO.
I chose the OPA2064 years ago as it is a good allrounder without any "outstandings" but with many "goods" and "very good", especially on bass-midbass, warmth and color presentation that make me able to listen for prolonged time without irritation and fatigue. This player is really nice in its present condition, equally able with Classical and Jazz.

I swapped the Headphone section opamp from OPA2064 to Burson Audio V6 Vivid very easilly, though I consider that the pins that come with the unit are slightly thinner than what I am acustomed to. Looked fragile to me so I was careful.
Luckily, the overall tonal balance of the Burson mirrors the one of the OPA2064, which is no surprise you might say, as this opamp receives the signal from the previous unbalanced out opamps which are indeed OPA2064 (more on that later), yes but it sounds like the OPA on steroids, and after a week or of use I confirm that this is a significant upgrade, soundwise.
For example, the string attacks on Myaskovsky's String Quartets had more definition, bite and HF harmonics and the natural melodic curves are better delineated. I have a game which is called "where is the Viola" where one has to detect the sound of this (usually) "non-solist" instrument...well, here we can not only hear but follow the Viola's contribution. The sense of the recording space is more obvious and the decays of the notes is mopre prolonged. The OPAs produce a warm tone which is welcomed with modern digital recordings of chamber music and the Burson kept that warmth but reveiled more texture and nuances in the playing.
The attacks in percussion and bronze wind intruments is also more violent, richly textured and expansive in Mombasa's African style Jazz.
The scale of the sound presentation is increased and maitains a well kept order in Shostakovich Violin Concerto°1, also in big fff tuttis. The emotional tension of the long melodic lines is contagiously expressed. Overall, the Burson opamp made me see further into the music, with much more detail and tonal richness, better painting of the curves of the musical phrases, better enjoyment of the rithmic variation. to the point I am feeling I need to upgrade my Beyerdinamics...any advise is welcome.

But all of this improvement was with the signal fed from the previous OAP2064s....today I swapped the unbalanced out for LN4562, of which I have a bunch, and to my surprise the Player sounds now only a bit more "dry" or less warm, but not cold at all, which was my reason to abandon this opamp in the first place, but more and more detail is comming out, with the tonal balance now shifted towards the medium high and high frequencies, but with deep bass and punch when needed.
For example, in Ferenc Fricsay's 1954 version of "The Rite of The Spring" one is more able to folllow several richly textured instrumental lines at a time, which was previously very difficult, and the big strikes on the Big drum are very explosive with a long decay.
In Halley Cat from Nucleus the cymballs produce an all encompassing atmosphere around the playground of the trumpet and saxo, which was previously only guessed. I am having many gestaltic moments with this new combination, digging deeper into the music.

For those who know how to build one , a discrete output is very recommended. For those who can afford one (or 3) a Burson opamp will give you a much more Vivid (pun intended) musical experience.

This is my humble opinion.
Cheers,
M.

Prevailing design these days is for the rounding over of everything on the front baffle, commonly blending into a waveguide as wide as the woofer. I find this unbearably ugly. While considering the details for my current project (small 10l cabinet nearfields) I'm wondering a) how significant a difference this makes and b) are there any other options to the rounded over and smushed out.

If i put a flat 45 degree chamfer around the baffle edge, instead of rounded edges, what is the actual effect it is going to have? a wobble in the response of maybe 1-2db? or is it something more magnificent? the somewhat famous LS35a design had a thick ring of felt around the tweeter to prevent the wavefront even encountering the edge of the baffle. Is something like this a valid option? You don't see this approach being taken these days. Another thing you don't see are those odd JBL accoustic lenses, even they looked better than waveguides, just.

I suppose i am hoping for a cool looking 3d printable metamaterial lens or something 😀

Hello! This is my first time posting on this forum! I just finished a build for a personal set of speakers with a woofer and a compression driver with a horn attached which was very fun! I'm moving on to my next project where I would like to build a pair of studio monitors with a relatively flat frequency response, are there any well known drivers (tweeter and woofer) that anyone would recommend which would be a good fit for a reference pair? Thanks!

Hello,
I’ve recently bought a not working NAD 216THX for $110 the seller stated only relay not working needs replacement, I bought the amp knowing it’s not only the relay so not a disappointment, I did replace the relay with the exact same model not newer not older, and still nothing. All the caps seem visually fine so I’ve taken some voltage readings on some jumpers that make logical sense to me as I don’t know where to get started. Just some background I’ve never worked on amps or any kind of other electronics other than making some crossovers. Here are the readings I got (this is with black probe on chassis and red probe probing and AMP powered on)

Left Ch.

J303 -19.3V
J305 -61.9V
J307 0V (makes sense it’s GND)
J309 62V

Right Ch.
J304 -21.5V
J306 -61.7V
J308 0V (makes sense it’s GND)
J310 61.8V

+Vl 61.8V
+Vr 61.8V
-Vl -61.8V
-Vr -61.8V

I’ve also included some pictures of the AMP and I found the service manual but once again, don’t know where to start.

I've got a very nice example of this amplifier here but there is no sound output on either aux or video channels. Every other channel plays great but nothing from aux or video.
Looking at the schematic, I see no reason why these shouldn't be working while the rest are.
Has anybody had an issue similar to this with this model or similar?

Hi just wondering if anyone knew of a reasonable compact design for these speakers.
I previously had them in kirishima cabinets, but those days are gone of huge cabinets in my front room. so want to either build or buy some that are more compact. Appreciate the bass will be limited.
Thanks all.
Ps, if anyone has any cabinets that they are not wanting that will suit... Even better.

Dear diyAudio Community,

I'm currently restoring my Technics SU 8080 integrated amp. I replaced all the electrolitycs, except the power supply ones, with Panasonc FCs, FRs and Elna Silmic2s. Cleaned allthe switches, pots and the speaker relay. Replaced half of the small transistors and all double transistors (2SA798). I know this issue had been somewhat discussed on Audiokarma forums before and no one really had an answer. I'm hoping, that since then, maybe, someone on this forum managed to actually get this power limiter boards adjusted according to the service manual or not.

I used the service manual for all the adjustments as follows:
1. Adjustment of (-B) voltage (negative power supply). I adjusted it to -44.5v according to the service manual with no problem;
2. Adjustment of speaker terminal DC balance. I adjusted it according to the service manual to 0mV, both in "DC" and "low cut" switch positions with no problem;
3. ICQ (idling of power transistor) adjustment. I adjusted it according to the service manual to 15mV with no problem;
4. Adjustment of power limiter is THE PROBLEM for me. I could NOT adjust these boards’ value according to the service manual at all. Whatever I do with trimmer potentiomenters R350 and R351 according to the service manual the waveform on the oscilloscope screen does NOT change all, niether its' vertical symmetry, nor its' amplitude.

So, has anyone actually managed to adjust this power limiter boards on the amp as per service manual or adjustment section Number 4?
What 1kHz test signal amplitude/voltage has to be applied to the amp input?
Do you need to connect resistive load (8 or 4 Ohms) to speaker terminals for this adjustment to be made? The service manual doesn’t tell anything about test signal amplitude/voltage or resistive load for this adjustment.

Sincerely,
Ivan Terekhov

From Volume 3 of "Linear Audio". It sims out very well. Here's a possible PCB 3D image:

I received another bin of unfinished projects and I am trying to decide if I can salvage an almost complete β22 kit.

I do not understand the 3rd board for an "active ground" in the recommended set-up.
So, I would not want to use that.

I would most likely use 2 β22 boards for the amp and 1 σ22 board for the power supply.

The AMB website covers this option as follows:



With this note:

"The wiring scheme for the 2-channel passive-ground configuration is shown in the illustration above. Of particular note is the ground-return wiring from the headphone jack. It should be connected directly to ground at the power supply (e.g., one of the σ22's "G" terminals). Do not connect the ground-return from the jack back to the β22 board. If the PSU is located in a separate chassis (as shown), then the ground return wire should be part of the inter-chassis umbilical cable."

I am a little confused because according to the schematic, signal ground and power ground are connected on the β22 board, so the ground return from the headphone jack is in fact connected to both signal and power ground. Why insist that headphone jack ground return be a direct line back to the power supply ground?

Can this be built in a more "normal" way without risking ground loops?

hi, I am new to Speaker crossover building, I have a set of speaker, it original crossover was quiet complicated. as shown in the attachment, it has many components, at the crossover point:2300hz.

When I frequency test each speaker driver, I realize the woofer driver has natural slop from 2500hz. so I simplified the crossover: leave the Woofer as it is without any crossover components, just add a 3.3UF caps to the tweeter, the new Crossover point is at 3300HZ.

When I try to compare both of the crossovers, the frequency almost the same, sounding almost the same in term of bass, mids and heights, and my simplified crossover feeling more sensitive, plays slightly louder.

so my question is:
When designing a crossover is it that true having fewer components is better so to preserve the speaker's original sounding?
do more components make the speaker sound better?

Can anyone recommend a good uk service agent, other than Arcam themselves, that could take a look at an Arcam A49 integrated that is not turning on not even the led is lighting. Have checked the internal fuses can see and they are ok.

Cheers! I am seeking advice and guidance in attempts to restore a piece of analog audio history.
This Mitsubishi DAr10 receiver powers up passing a dim bulb test. However, relays do not click in; there is no sound produced in either channel. The preamp is OK. I can get a signal from the tuner with measurable output on REC OUT. Voltages in the amp circuits resemble what is shown at 'test points' in the SM.
(see attached jpgs. I could not upload the entire SM or copy/paste from the PDF. )
An STK1050 power IC produces output for each channel. Measurements for IC601/left channel were way off. Voltage readings on IC501 seem OK.

Additionally, the DC offset on L601 was in the order of volts! not mV! This could NOT be adjusted by VR601. Looks like the left channel either received a 'blow' or simply failed due to age. I removed the STKs, the impressive heat sink, and decades of domestic detritus. Also purchased new 1050s from SEMITRON on eBay.

I came upon a clever way to trouble shoot an amp circuit like this:
STKs removed, solder 4 resistors of equal value to jump in/out pin pads , gain down, preamp set to aux. My pairs are 1,4 and 0,7. — a Trouble-Shooting Setup…
I was expecting the relays to engage ---no click... suggesting the HA12002 protection IC failed. Replaced it. (I was correct) Now, relays engage and the DC offset on L601 was reduced but still high and unresponsive to turns on the trimmer (VR601).

Taking a closer 'look' at the circuit involved w/DC offset --the N-channel JFET (Q601)-- and the trimmer responsible for adjusting DC offset; desoldered and tested - it is OK. Readings from the gate to R615, 614 did not compare to those on Q501. Since this gate is linked to L601 through C606, R612, R613 I pulled these out- tested OK- reinstalled --Presto! the trimmer now works (very touchy) to zero out the DC on L601.
Must have been a 'cold' or oxidized joint. DC offset now acceptable.

Now, a return to comparing voltages between the two channels raises questions.
(pads 1,4 jumped; pads 0,7 jumped w/470 Ohm resistor)
Readings taken at the power IC terminals:
IC 601 terminals IC 501 terminals
pin 1 -3.5 V -.77 V
pin 2 -42.4 V -42.6 V
pin 4* 0.5 mV -0.2 mV
pin 7* 0.5 mV -0.2 mV
pin 8 ( not included )
pin 9 42.3 V 42.3 V
pin 0 3.48 V .75 V

Pins 3,5,6 not used in this amp design.
*(4,7 measured with Fluke DMM; mV setting w/an averaging function - these voltages tend to wander.)

Questions:
I can infer that there is a DC 'balance' within each channel, but what about between? Why is there that difference between the channels on the #1,#0 pads. Is this a problem? Is this a matter of incorrect idle current/DC bias?

Probing around the transistors with this Trouble-Shooting setup, I find the dc voltages between the two sides comparable until Q504/Q604, Q507/Q607 where a marked difference appears between the values @the collector of these transistors. The left channel, i.e., Q604/Q607 shows plus & minus 3.47V vs plus/minus .75V on Q504/Q507.
The schematic shows +1.2/-1.2 volts at the #0, #1 points which is the connection to these collectors. Maybe this is only when the STKs are in place. (I recall seeing this 1.2 V before the tear down on the 'good' IC501, right channel).


Here, my novice status becomes apparent.
Does this difference of about 2.75 V matter at all?
I can't explain why, at this drive stage, each side is not producing the same or comparable voltage. Indeed, what is the 'correct' voltage. I don’t see a way to adjust bias. Does this matter?

Testing Results:
A) the protection IC had failed; replaced - relays working
B) reflowing some components around the left channel JFET returned the DC
offset trimmer to 'functional’. DC offset now within specs.
C) the output module, IC601, had failed (via comparative ohms & diode testing) - I have two new STKs in hand
D) a difference of about 2.75V exists between the two sides with regard to DC being presented to the output modules.

Finally.....do you think I should simply install the new STKs at this point ?
Thanks for any feedback/insights.

SOLD I am selling these amplifier boards cheap as they are in unknown condition. They have been collecting dust in my closet for years . I found a spare set of output Mosfets I will throw in no charge. $30 plus $20.00 postage.

Hi,

I am modifying the PCB of a GuitarPort audio interface. It's a pretty old product and they go for penny's on eBay. I got this one for 99p, so just fancied hacking about.

I've disassembled it, and it's got a tl072c right next to the guitar jack input, so I'm assuming that's the preamp and therefore will be the most important component to replace if I want to upgrade this interface? I've not modified circuits like this before, but I've got a lot of experience in SMD rework (component replacement etc).

Received about a year ago a severely defective Hakko soldering iron, only discovered it is severely defective long after the warranty has expired. When set to 850*C and has fully warmed up, no increase in temperature, the actual temperature of the tip is just under 150*C. 😳

Has anyone experienced this and successfully repaired this terrible deficiency?

Thanks in advance! 🙂

PS Why is it nothing of any reliability comes out of China? Rhetorical question, we know it is because no fully Communist country can manufacture anything like the Western world. No one made anything as good as the Dutch, Germans, and the Swedish, though might be a tad biased being Dutch, English, Frisian, German, Irish, Norman, Pomeranian, Prussian, Swedish, and Welsh. Ha.

I have recently built a uTracer6 and noted a measurement accuracy issue using Ronald's GUI.
If you do a sweep with the (Va=Vs,Vg) the GUI seems to incorrectly report the test voltage for the screen current being measured.
The result can be large errors in the data collected for any (Va=Vs, Vg) sweep that involves a large test current delta between the anode and screen ports.
This is most notable at lower test voltages and high test currents.
For example if a high current pentode is measured in triode mode (think sweep tube) where a large delta is present between a high anode current and the screen current there can be a significant discrepancy in the test voltages used for the actual measurement and what voltage is reported by the GUI.
This can under some condition result in large errors in reported results.
To confirm this I measured a 50 ohm resistor on the anode port and then on the screen port.
With Ronald's GUI testing a 50 ohm resistor on the anode port and taking the reported test voltages and currents from the GUI, calculation confirms a 50 resistor is being measured.
Repeat this with the screen port and the GUI results suggest in error a 100 ohm resistor is being measured.

Note this seems to not be a defect with the uTracer6 hardware or firmware but only seems to be a issue with the present GUI.
I confirmed this by remeasuring the 50 ohm test resistor using the utMax GUI and then for both anode and screen ports the GUI returned the correct voltages and currents for a 50 ohm test resistor.
At this point I do not know if any other test modes other than (Va=Vs,Vg) on Ronald's GUI are affected on the uTracer6.

I have had a uTracer3+ for many years and not noticed this issue with the uTracer3+.
I do however use a older GUI version with my uTracer3+ than the latest version I am using with the uTracer6.
As well the uTracer3+ can not measure the high currents that a uTracer6 can and I only see this issue at higher currents on the uTracer6.

I have to move, everything must go including my Slagle Autoformers.

These are the nickel core inductors mounted to a circuit board design by John Chapman with gross and fine adjustments as sold on the Intact Audio site. I have just gently put them in a nice box, wired with Alpha silver plated copper wire. You can have the Mahogany case or not, DIYers might like their own soldering done and the modules are easy enough to free from their home and ship. - buyer pays actual shipping from 49685 Michigan, USA.

$300.00

Yaqin MC-5881A

I bought one of these off ebay, and as soon as it comes, I'll trace the circuit, measure the voltages etc. and ask you knowledgeable chums for advice what components to change/improve. Not a major rebuild, just obvious mistakes if any and similar.

Anyone that already has the circuit, perhaps? This thing is also known as Yaqin (or Yaoin) MC-6L6 and Markhill MC-6L6.

I have a sick Exposure IV, and am hoping someone can tell me what might replace the EXPP/EXPN o/p transistors please?
I'm aware that the MJ15004/3 combination can be used.

I'm 'informed' that the MJ21193/4 combo is also an option....and I'm interested in taking this further, as I have easy access to these 🙂
Can they be used, and would any changes to the circuit be required if I opt for 'em please??

I've attached a circuit diagram.

This is my modular AK4490 DAC that I made last year.


I started the design a few years back when I needed an optical SPDIF input for my TDA1541 DAC with tube buffer. Instead of buying something from China I decided to make my own. After all this is do-it-yourself audio, not buy-yourself-chinese-stuff audio.

First I made an integrated SPDIF board with AK4118 and STM32F030. Then I decided to add an AK4490 DAC. Then later AK4137 SRC. Soon I found a need to have a separate STM32F030 control board for other projects so I decided to make this more modular.

Now it contains 5 separate boards:
1. AK4118 receiver with optional AK4137. The board has coax and optical inputs as well as 1 optical output for SPDIF bridging. The board can output I2S via AK4137 or directly from AK4118 so the SRC can be truly bypassed. There is also an additional I2S input to AK4137 for an external USB-to-I2S board.
BTW fittingly the coax spdif input is based on Jocko's design (or rather advice to a fellow member) from 2005.
2. AK4490 board which is more or less according to datasheet with LM4562 as LPF Opamp. LT3042 regulators for VREFL/VREFR.
3. XLR "shield" for balanced output (2 LM4562 opamps).
4. STM32F030 control board with headers for HD44780, encoder, I2C, IR receiver and I/O.
5. Encoder board that has HW debouncers for encoder and switch. No SW debouncing needed.

The DAC can be powered by e.g. a SilentSwitcher with a battery pack (as seen in picture above).

The performance is close to datasheet level. THD is very close to the measurement limit of my setup. Here is the FFT spectrum for 44.1kHz/24bit SPDIF input.


Here are pictures of the DAC board and the XLR "shield".




Now all it needs is a chassis. Also the SW is still work-in-progress. But all in all a very educational project. Buying similar boards ready-made would have been much easier (and a lot cheaper!) but where's the fun in it.

Hello friends.

InConcert Miles 2022.
Project finished.

The original speaker was designed and constructed by Stig Erik Tangen.
You can find more information on the internet searching for "InConcert Miles".

Inspired by Hunsbedt Trebygg, "Karmann" from AVforum.ro, "BEF-NO" from AVSforum and "atledreier" from HomeTheaterShack".
I always had a weak heart for huge cone's.
Therefore I liked to built this configuration.
Here's the version in my own jacket.
Highs and lows designed and put in seperate cabinets.
I already heard the test installation here in my living room.
This sounds as music in my ears!
High-efficiency speakers with a wonderful depth, spaciousness and detail.
Also a very nice 3D sound production.
And now they are ready!
Fabulous!
This is sounding huge great open and very deep in my living room!
Very Happy with them.

Here some pictures during building process.

What is the Break-in time for the CHN-110 - Mark Audio?

somebody can give me some tips for the break-in time?

I am about to finish my box and want to break-in this speakers correctly

and also know more os less when I can expect beginning to hear what this speaker can give 🙂

Hello,

I've had my Adam A7X pair for about 8 years and one of the transformers just gave up. I sent it to my regular technician to try a recoil, but it seems like this is way more difficult than expected so I'll need to get a new transformer. The local distributor has changed hands a few times, so the new distributors don't seem too inclined to help much, since I did not buy the unit from them.

Would anyone know where I can buy a replacement transformer for an A7X?

For context, I live in Malaysia, so there aren't really a lot of options and will probably have to buy either recondition on ebay or from someone overseas and have it shipped.

Thanks in advance!

Error correcting feedbacks compare the weighted output with the input and feedbacks only the error. It is possible to correct in open loop by subtracting/adding the difference with a bridged amplifier.
Here is another way of subtracting with very little feedback.
The error is already between the inputs, it is added to the negative input after inverting. By this what was lacking in the output is add. Due to slight feedback, it is amplified by only 1.057 to near perfect cancelation.

This is a lm3886 model with a gain of 26db. Stand alone, it has a noise of 5.5mv in 20-20khz BW. By subtraction, it becomes 32uv. This is 180 times reduction in anomalies. The circuit as is, is unstable as it also increased the frequency response.
In real world, using NE5534 as differential, it needed a gain of 1.31 for minimum noise of 120uv and reduction in gain to set it back 26db. A capacitor made the circuit stable.

Selling 4x Lundahl LL1638 chokes
4H 400ma, like new

65€/piece, will ship worldwide

I’m going to apply a series capacitor tuning technique on my closed-box speakers. There is a confusion on the correct placement when there are examples with different locations.

Firstly, the papers such as Thiele, von Reckling- hausen, and SB Acoustic’s suggest placing the capacitor directly in series with the driver. However, some well-known speaker manufacturers such as Infinity, Wharfedale, etc. placed the capacitor in front of (before) woofer’s low-pass filter, according to the crossover schematics. And, finally, there’s a sense that the capacitor may be able to be installed at the speaker terminals. Thus, which one is the correct position?

Seems like I have an account since 2021 but never posted anything yet !
So, hello, Seon, living in Tokyo !
I have been messing with electronic for a few years now, learning by myself while fixing recording gears for friends and a few junks I find in second hand shops from time to time.
This year I'd love to level up and become able to make my own circuits too !
I would love to build a little mixer someday as a centre piece for my homestudio.
Nice to meet you!

In several places I've seen the method described for measuring/ calculating free air resonance Fs and Qts of a loudspeaker driver. For example, see Section 1.1 of this article by Rod Elliott-

http://www.sound-au.com/tsp.htm

So my question is, can this methodology be successfully applied to a closed-box loudspeaker system? After building a closed-box system, I wanted to check that Fc and Qtc actually are what I intended them to be. I imagine this is something that quite a few other builders would like to do.

Thanks if you know,
Pete

Hello guys, I hope you are all doing well.
I'm new to amplifiers and sound systems so I don't know much about them. I'm building a small sound system for my room, this is the setup for just the subwoofer. I have purchased the bluetooth module, pre-amp and power-amp from AliExpress so they aren't of very high quality.
The Pre-amp and Power-amp run on 12 volts while the bluetooth module operates at 5 volts. The Power-amp is rated at 150 watts max. My Subwoofer is dual coil, 1.2 ohm (I guess it becomes 2.4 ohms when I connect the coils in series), and 60 watts RMS, 150 watts max.
I need your help with the connections. Here's how I did it:
The three wires from Bluetooth module (R G L) go into the Pre-amp, the output wires (two wires) from the Pre-Amp go into the input of the Power-amp. The two output wires from the powe-amp go into the subwoofer.
I'm feeding this system with a 12v 10A power adapter.
These are the issues I'm facing:
1. There is a constant noise in the subwoofer. When I disconnect the audio input wires from the pre-amp, the noise goes away. If I take out the pre-amp completely, there's still a buzz in the Power-amp.
2. The sound volume starts to fluctuate after a while. It goes up and down on its own.
3. Sometimes I hear ticking noises in the subwoofer, it's not clipping because I can hear them even when the volume is very low.
I'm attaching a rough diagram of these circuits. Please pardon me if I'm doing something wrong. Your help will be appreciated.

it is out of audio topic but maybe some electrician expert can help me.
I live on Germany here we have 3 phase power star with center neutral to ground,each phase to neutral 230v and phase to phase 400v. max allowed current per phase 20A
unfortunately I have an electric car that can charge 7kw 230v 32A monophase no 3 phase
I could slavage 2 toroidal transformer 230v 230v 7kVA from solar inverter.
so I wired primaries in series connected to phase 1 and pase 2 they receive 400v, 200v each primary up to 20A
secondaries are in parallel they provide 200v up to 40A
electric car charges fine up to 24A but more than. that it stops because the voltage gore below 190v (sag from cables and toroids)
I am fine with that and at 24A all works fine.
To avoid the undervoltage cut off I added a third transformer at the secondaries of the 2 big toroids to increase the voltage from 200 to 220v
it is a 1KVA EI transformer 230v 24v 40A connected as autotransformer.
I get 220v the car charges up to 20A but if I increase the amps then the loading cable device (the one that tells to the car ar what amps it has to charge) makes a reset, screen goes dark and more strangely after a few seconds the 20A circuit braker at the primary (400v) side, trips. I reproduced this 3 times.
I suppose that maybe the loading cable device RCD senses a loss to ground, my EI transformer was lying on moist soil, I could understand a reset of three charging device
but why is the circuit brakes tripping?

hos is it possible that more than 20A are flowing for an instant? peak overcurrent?

Good day bros. I hope every body are well and good. It's my first time repairing a Deaf Bones car amp and did not expect that they replaced the part numbers of all the important components of the amplifier. As I found out after troubleshooting 2 output FETS are shorted I believe the chip drivers are gone too which caused the clipping problem upon power on. Can anybody please tell me the exact component part numbers of the output FETs (labeled B1) ,supply FETs (labeled H1) and the drive chip (labeled C5) which are all shown circled in white in my photos. It would be a big help to me because some Deaf Bones dealer pop out in my place lately and a lot now are in the market. Your response are very much appreciated. Thank you very much.
More power and good health to all.

I recently built a Sangaku and whenever I plug headphones into the 1/4 jack there is a persistent clicking sound. It's reminiscent of a chain moving through a gear, I've attached a video below. (it's very quiet, you may need to turn the volume up quite a bit.) This is most prominent on my Beyer T5p, although it's almost as present on my Beyer T70 (the 250 ohm version), Sennheiser HD800s, and less so on the Hifiman HE400i. It's basically nonexistent on the SJY Moonlight or HIfiman HE6se (not surprisingly). I'm not sure where I could have gone wrong here. The only thing I'm missing right now is the 3 switches for the front and the front and rear panels. I used a bit of cable to connect everything in the place of that. Any ideas what could be causing this?
Source is a Ayre Acoustics Codex and I already checked that.

Looking to purchase a quantity of 26DQ5 sweep tubes.

Please let me know if you have any

Thanks!

Greetings all,

Listening to the SSB voice on ham radio may be an unpleasant experience due to the speakers used (small, inefficient), their mounting (up or side firing), amplifiers with higher (10%) distortion, and the like, even in better transceivers. Although most transceiver include phone output, I do not like using phones for various reasons. Interestingly, some of the new higher tier - and price transceivers now include option to add (multiple) speakers with a rathr sophisticated processing.

That made me start to think about adding external speakers.

The SSB audio bandwidth is about 300 Hz to 3300 Hz, but adjustable filters are used to (usually) narrow the bandwidth, but sometimes the filters are used to shift the lower and/or higher edge, e.g. to avoid close signal. Thus the speaker should cover the bandwidth from 250 Hz to 3600 Hz with excellent intelligibility.

The speakers should have high efficiency so that a battery operated, and such small and low noise amplifier, could be used.

Although I do not think that a low distortion would be difficult to achieve, for the sake of completeness, I am adding this requirement so that the already distorted signal by, e.g., narrow filter settings, noise, etc. is not degraded further.

I was initially contemplating a single-driver speaker, but then I though that I will also be using the speakers for casual music or speech listening, so perhaps a two-way would be better choice. I was contemplated a wave-guide loaded tweeter (higher efficiency, better focus), either off-the shelf or using one aguerpro’s wave-guides from the "Open source Waveguides for CNC & 3D printing!" thread, mated to a low distortion mid-range/woofer.

So, if you could point me to some designs/kits, I would appreciate it.

Kindest regards,

M

I've got this Quadraflex Reference 450R receiver and I would like to replace the power supply capacitors. There are no schematics for it anywhere online or in print form so I'm hoping someone can say for certain if the two large black capacitors near the output transistors are for the output stage or the power supply. They are marked 6800uF 50V.

Please see the following photos. The third photo is of the Power Supply Board.





Power Supply Board...

I have some some Nichicon SE electrolytic caps that I found in the wrong place. Google could not find any data on them Does anyone know anything about them ? are they low leakage, audio or general purpose or ???

they are regular through the hole 47uf caps that have SE (M) printed on them



I am asking cause I just want to know !!

Hi all,

I've been winding a few custom output transformers using M6, Z11 (and some unknown laminates in the junkbox) for guitar amps with surprisingly good results. I once got this advice from Sensei Ingo:

Lamination: The old Marshall Transformers used the British steel named "Vicor", a semi processed steel. This "Quality" is obsolete and isn´t available any longer. So what to do. For good results for a first project just look for the semi processed steel 660-50.

Click to expand...

I have tried to found out what Ingo referred to but failed so far. Does anyone know what "semi processed steel 660-50" is and where to source it, or perhaps something that is similar?

My next project is an EL84 based 18W "Plexi". I would like to use this laminate and find out if it's the unicorn blood I've been looking for so long...

Thanks in advance!

/Mike

Hello all,

The output signal is attached. I wanted to know if it is normal to have such big frequency at both speaker outputs. This is there with and without signal given. Thank you

Update: all is sold.

Someone asked me to fix a Quake but the bridge and fuse area of the board was so badly burned out. I've tried to get it working but it sounds like DC leaking. The sub vibrates with a loud hum where the cone is moving so rapidly.

I'd like to fix it, I replaced the mosfets, and bridge diodes etc but was wondering if anyone with more knowledge than myself could help me find a replacement board to stick in there.

After developing some limited skills in bending wood with the Tasmanian Devil home streamer, I'd like to try next a pair of large bookshelf/small standmounts using bent wood.

This time I'd like to try a rounded triangular prism design which I find just as visually appealing as the rounded rectangle of the home streamer. Speakers in my experience spend a lot of time not being used so it's helpful if they look nice even while asleep. Curves I find relaxing but seem to be rarely used in the commercial world, possibly because of cost/difficulty of construction? As I'm already finding with the home streamer, curves also seem to help rather than hinder good sound. The triangular design has only front and rear on the same plane, bottom and sides are on 3 different planes. Dave has mentioned several times on the forum that BR shape is not important, only volume, so I hope that applies here. This would be a rear-ported design unless anyone has other thoughts.

I've found a few triangular speakers online but they seem to be mainly small corner speakers or floorstanding pyramids. Has anyone tried building something like this? I have no test or measuring equipment other than my ears (and Mac-based simulation software is hard to find), so would like your help in deciding a) whether the shape is viable and if so b) which driver configuration and units to use.

They will be used in a 6m x 5m lounge and I'd like them on cylindrical stands (I'm thinking the tree trunk look!) for all types of music. Good sound stage needed, balanced performance across the spectrum, to be used with an integrated streaming amp such as the Wiiim amp or Bluesound Powernode. Since appearance and geometry is important, the drivers will need to look and work well in a triangular baffle. Colour scheme this time will be black, white and silver, so no gold drivers this time around. Probably an all-white exterior with black, white or silver drivers. Tweeter if used must be robust to prevent finger-poking, so no soft domes unless they have a front grill.

Attached are four ideas: FR, 2-way, 2-way with ribbon tweeter and small 3-way. Would love to hear you thoughts on which one to go with and what drivers to use. WAW or coax could also be an option if they could be made to fit into the shape. The geometry of the standard 2-way currently appeals (best match for the sloping sides) but I'm open to any of them. Driver budget is US$500-700 for the pair (including crossovers if needed). Could go higher for something special. Size can be anything from 12 to 24 inches tall to suit the chosen driver(s) although volume will be about half that of a rectangular box of the same height and footprint. But to me that's worth it to have something that will hopefully bring a smile to everyone who sees and listens to them.

Thanks all.

Dear all,

I know the basics: a SE OPT amplifier needs a gap to avoid core saturation, the PP avoids the (big) gap as DC currents cancel out. Since I joined Diyaudio discussions regularly pop up about PP transformers being used with only one side driven, the other side being loaded by a CCS (a mosfet or a tube), this allows the SE sonic signature using PP OPTs (smaller, maybe available).

I can’t remember having seen an amplifier that allows (gradual) transition between PP and SE, preferably keeping the gain constant. I saw/have some ideas, like feeding a balanced PP amplifier with an input transformer loaded by a potentiometer, with the wiper connected to ground. In the middle position both legs get the same signal, the amp is PP. Turning the pot, each leg becomes a different signal, something between PP and SE. With the wiper at the extreme of the pot, the amp operates in a sort of SE (but take care that this one leg is not clipping because it now gets twice the signal as in PP operation). But say the amp uses triode output tubes, in the SE case one may not be amplifying, it is however still loading the transformer with its low plate impedance. Good or bad?

Please share existing projects, your ideas or schematics. Given the circuit is doable I am willing to build a prototype, I have input transformers (LL1540), OPTs, lots of different driver and output tubes, not afraid of using mosfets (enhancement and depletion), have multiple adjustable PS that can all be used for testing.

The purpose of this exercise is to have an amplifier that can play multiple distortion signatures by turning pots or maybe some switches, so the influence of variables as PS, employed output tubes, OPTs, being warmed up or not are kept to a minimum. Constant gain would be nice as I plan to use this for the midrange in a bi-amplified system, and because differences in gain can also be perceived as differences in SQ.

Many thanks for your ideas!
Erik

Hi guys and gals, liftime of electronics, found the tda7293,4, exploding caused by stanby and mute, chip manufacturing was changed but datasheet no longer relecrs the changes. The MAX voltages used to be the v+ but now causes the chip to explode, limit the stanby and mute voltage to 5 volts eather with zener diode or resistor devider, before the rc network described, also do not connect 2 chips mute or stanby together as if one chip fails both chips will blow.

Hello community from Germany.

I'm new to the forum and I can say that I'm ignorant in terms of calculation, development and especially the subtleties of a quality enclosure, but luckily I'm good at implementing it. In the last month I've spent a lot of time going through the forum and especially the FR part of it, looking for information related to a combo FR driver - enclosure for the listening room. Unfortunately, I am totally overwhelmed by the multitude of right combinations, for which I appeal to the well-known kindness of the community of this forum. I would like you to recommend me a combo driver - enclosure for a 30 square meter room which is already fairly neutral acoustically. Favorite music is Jazz and slow blues 90% the rest classical and others,low to medium listening level.For size it can reach up to medium (up to 1.2m high). As it is discussed heatedly and he knows that there is no perfection in measurements, so I will not want something like that, I want him to sing naturally as pleasantly as possible for connoisseurs. I am open to any proposal from you.
Thank you in advance for your support.
Alex

Hi all,

I picked up some GW-8004 coaxial full range drivers, they have a built in crossover. I picked them up because they have high Qts and seem to have quite a bit of excursion travel potential. This is the driver:

https://www.parts-express.com/Goldwood-GW-8004-8-8-Coaxial-Speaker-290-378?quantity=1



Here's the manufacturer graph response:



Here's the manufacturer T&S:



I went ahead and measured it myself on DATS V3. All 4 drivers measured very similar to this:





Here's a near field (3" non-anechoic) no baffle measurement (driver suspended in the air more than 3 feet away from surfaces, etc). I didn't gate or anything just to see a general idea of what it was doing. Mostly looking at that 3~6khz dip. The roll off is expected under 1khz I think here. And the rest was ok.



I used Basta to look at potential baffle sizes. After playing in that and doing some calculations for baffle width and all, I realized, it won't matter because I'll never make this large enough to support really low frequencies. I potentially would like to get down to 100~120hz with these after EQ with some boundary gain (they will mount near walls all the time). But I calculated a rather large 3.4m baffle to do that. Obviously impractical. And so the differences from 24 inches and smaller didn't seem to matter. So I figured, I'd just measure it and see what I could do.

I made a few baffles that were around the sizes I wanted to work within and made some temporary wings to extend the baffle while reducing the front baffle width here and there.

I started with 12" x 18" baffle with and without 3" wings on the sides.



Here's a few measurements. These are just near field but non-anechoic, I know they're not accurate, just looking at the overall shape of the response based on the baffle which should show up ok with fairly near field. The black line is no wings, so the baffle width for bass is 12" x 18". The other lines are two different position measurements with 3" wings ont he sides and they were more consistent but it was clear the extra baffle width helped lift the bass under 400hz.



Next, I wanted to shrink the front baffle some so I reduced to 10" x 15" and kept the 3" wings.





I later added some cut out notches around the tweeter to see if it would matter. I know this is a practice to explore with tweeter + woofer two-ways, but I didn't know if it would help with a coaxial driver like this. I don't think it matters at all, so I likely will leave the notch out in the final version. Overall I think the 10" x 15" with 3" wings (16" baffle width, by 15" height, for bass) still seems to keep enough bass for this purpose near a boundary (walls, ceiling, floor, etc). I know it will have different response from a vast distance. I will measure that soon. For now, just trying to get quick measurements just to see the baffle width changes and the bass response.

Blue line is no notch.
Black line is with a notch centered around the tweeter the size of the tweeter diameter.
It didn't seem to matter much. It maybe took down some output from the mids and treble by 1db to 2db or so here and there, but it also lost 1~2db in bass.



=================================================================

So, some comments and questions for anyone willing to help out:

1 - These are going to be used as surrounds so they will not get a lot of primary use. I mainly am looking at getting 100~120hz to 15~16khz bandwidth from them. They don't have to be flat and I'm going to EQ some. I plan on increasing the low frequency a bit with boosting and maybe some cutting on the 1~2khz range mids and a bit at 7~14khz treble ranges a little, but not a lot. That's just for context of use. It's going to be mostly ambient stuff, effects, rarely ever going to be voice or instruments and will not be the primary source when listening. Again, these will be surrounds, just for context.

2 - I'm trying to figure out what I can do about that 3~6khz null. It's the driver. You can see in the free air measurement and on different baffles, it doesn't change or move. I measured a 2nd driver to compare and it has a similar one but its shifted to different frequencies a bit. I imagine this is just a constant I will have to live with, with these drivers. Some sort of cone break up or interference between the tweeter and woofer? Any help on what this is really and if there's anything that can be done with it (I doubt it)?

3 - Any suggestions on baffle sizes and/or the wings or notches? I don't think the notches matter here since the tweeter is in a coaxial. But I'm open to any suggestions. Ultimately I'm going for a slim depth on these as they will be near walls, so figure they will pick up some boundary gain a bit. I'll measure that soon after getting the baffle width ironed out. Any suggestions on 10" and 3~4" wings? They probably will end up in a U shape, as I think doing angled wings will be a bit beyond my craftsmanship abilities on long panels. I can do that with a miter on studs and stuff, but I don't have anything to do that on long panels.

After some more tinkering, I'll do a rough baffle and wings build with plywood and do some on-wall measurements after figuring out, with any help here, any changes to the baffle.

Thanks 🙂

Very best,

In the process of making my uTracer3+ (400V), tube curve tracer from https://www.dos4ever.com/uTracer3/uTracer3_pag0.html

I ordered the processor with program from Ronald at dos4ever.com, and as a true diyer made my own version of the PCB. I added all the mods to the original 3+, and added FDTI cable USB connector and two extra sections for the Grid Loupe and the Capacitor forming options.

I have also the extra higher heater current bulk converter from Albert Valiente and Voltage Volt/current meter options. I bought the bulk converter PCB and meter from Aliexpress, and made my own pcb for the HR supply using Albert design.

Albert mods, grid Loupe and Cap forming circuits can be found in the uTracer Lab Notebook PDF document.

More pictures will follow.

I have an original untouched Pa7 I bought new in ‘86. I am looking for info on updates that can make it better. I saw something about improving the bass in that there is evidently a roll off in the low end that can be improved pretty easily. Right now the amp sounds great and has no issues. I am just looking to make it as good as it can be.
All I have done is adjust bias and checked dc offset. I also replaced output binding posts with Cardas. Any help would be much appreciated.

Anyone have experience with they SBA SB15 5x8 woofer?

https://www.madisoundspeakerstore.c...ics-sb15sfcr39-4-5x8-paper-cone-woofer-4-ohm/

I am considering a narrow (e.g. appox 6-7" wide) tower 3 way, with an SBA tweeter at 4k, and the Scanspeak 10F for the mid down to around 300. The SB15 seems like a great option for the low end to fit nicely on the front panel, and 89db sensitive for the 4ohm version.

I love the long racktrack design. It reminds me of the Linn Keltiks I heard back in 1999. Those speakers still live in my memory.

That dip at 50hz tho. Is that something to be concerned about?

For my small sealed sub project, I settled on a sealed box design of 12"w x 18"h x12"d and a 10" driver from SB Acoustics. Approx 1ft3 /30l of internal volume. I am using as a passive design with an external amp.

I am using 3/4" baltic birch, and routering the ends of the panels to create notches on the side and top panels to maximize glue contact area, eliminate any gaps, and minimize the plywood edge exposed. I plan to add extra 1"x1"xL" blocks inside on all the edges for more panel glue contact to really make a strong seal and joint all the way around. I should have about 1.5in of glued wood along every edge.

For a small box, do I need to worry about extra bracing?

And, I see mixed opinions on adding damping materials on the inside walls/ stuffing in the box. Should I line the walls, add stuffing, or at this small size does it really even matter?

The low pass filter on my amp is set around 100Hz. This is really just for low end extension in my basement music/ 3.1HT setup. Low ceilings in my 1927 house, so I get decent room gain, and I small sub is all I need (and have room for).

Does anyone know how to set bias, and the parameters? Running at 24v.http://www.pmillett.com/file_downloads/Nutube_buffer_sch.pdf

Hi All

I have a NAD L75 small format surround receiver that I use as a 2-channel amplifier for my PC speaker setup.
It has developed an issue when powering on the unit. You can hear one of the relays clicking away multiple times but the amp does not immediately switch on. Sometimes after just a few relay 'clicks', sometimes many clicks that could last a minute or two, the unit does eventually power on and there are no operating issues from then on; everything seems to work fine. Often if you turn the unit off again and then back on it will turn on fine without issue. If it's left for a few days then it's highly likely to have the initial startup issue again. Recently this was also accompanied by some popping from the speakers while it was trying to power on so I'm not sure if this is a related issue or not. There is a second relay click a second or two after the unit powers on which I assume is the speaker protection circuit. Another possible clue is that the display when in standby mode [it just shows the time] is very dim and flickers on and off. Once the unit powers on, the display works as normal.

Below is a link to the service manual with schematics:
https://www.manualslib.com/manual/1422086/Nad-L75.html

I isolated the clicking relay at startup to the "AC Outlet PCB - KUP11431-2" RY91 - BSL1A008ZE - RELAY - SDT-S-112DMR and thought that may have been the issue so I replaced it which made no difference at all.

There are no obviously swollen caps that I can see, no burnt components etc. I'm assuming that the issue lies somewhere in the initial power supply boards before all the amplifier, decoder etc. but I'm a bit out of my depth as to what it could be. If anybody can assist and give me some direction on what the issue could be... I'm more than capable with a multi-meter, soldering iron etc. so fixing the issue shouldn't be too hard if we can work out what it is!

Thanks
Dave

Over in the PTT6.5 and RS28F TL thread, I was very impressed with the Purifi's midrange and bass abilities, so when I had the cabinets built I asked my cabinet maker to build a second set of baffles with a cutout for the RAAL 70-20xr ribbon tweeter. As I am waiting for the TL to get re-worked/re-built due to an improper seal in the internal channels I started to look at the RAAL 70-20xr as a pairing to pass the time by designing a XO. Since I don't have a back cabinet yet, I mounted everything open baffle figuring I will just work on the XO as it will be at 3500Hz, far enough away from where the open baffle effects need to be considered.

Here is the TL cabinet that is getting built (aiming for -3dB at 36Hz):


So I installed the drivers on the spare baffle - everything went together nicely. I installed some MakerBeam channels to provide temporary support for the measurements. The initial measurements and XO started off in the other thread, but they turned out so good I thought it deserved its own titled thread.

Here is the setup:




My reasoning for the 3500Hz crossover point was mainly driven by the PTT6.5's natural falloff there so I wanted to take advantage of a similar higher order slope using just a few simple components with 2nd order electrical and maybe 4th order acoustic. The Purifi is rated 88.5 dB at 2.83v and the RAAL has several transformer taps to allow adjustment of sensitivity without using a lot of resistors. The 12ohm tap is stated as about 89dB sensitivity so I opted for that. The factory recommended single crossover component was 4.7uF for a 1700Hz 4th order acoustic and 2nd order electrical. I was thinking use 2.2uF for 3400Hz and go for a 4th order XO circa 3500Hz.

So I connect the drivers to measure the raw response for the FRD files to load into Xsim to do the XO simulation. I used a 2.2uF cap in series with the RAAL as it cannot be driven by directly since it presents a 0.6ohm load the amp at DC. I proceed to take the usual "raw" data sets of (1) tweeter only; (2) woofer only; and (3) tweeter and woofer in parallel. This is to do the acoustic interferometry to adjust the relative acoustic center delays (due to voice coil location differences and baffle/bezel offsets). What came out of the "raw" data was almost a perfect "accidental" crossover that looked like it had been worked on laboriously. The two drivers are apparently, ideally matched - like they were meant for each other.

I was having issues with my SPL calibtration meter (reads about 5dB too high relative to know standards - a new better one is on order). So for now, please ignore the absolute SPL on the vertical axis. Data was taken with 2.0vrms (set at 1kHz) and 0.5m away on tweeter axis.

Here was the measured "raw" response for the tweeter (green), woofer (red) and combined (blue):


The above doesn't look like any other "raw" set of woofer and tweeter data I have ever seen before... Almost a perfect auto-crossover (only one component being the mandatory 2.2uF coupling cap for the tweeter).

Raw system measured acoustical phase:


Raw system harmonic distortion (there are some peaks from the RAAL at 1.7k, 2.6k, and 3.4kHz that I will need to look into more, but they are 2nd harmonic so not terribly high or bad sounding):


and this was the raw Step Response:


Using the FRD's from the above and ZMA's from a DATS, I loaded everthing into Xsim and was able to get what I think must by a hybrid 1st order/2nd order XO where at the crossover frequency it is -6dB/octave and changes smoothly to -12 to -18dB/octave farther away. This allowed me to use the same absolute polarity for both drivers. Applying just a 0.33mH coil with a 6.8ohm in paralle for a high shelf filter, and a 6.8uF and 0.51ohm in series across the woofer terminals to quash out the stuff above 3.5khz, I was able to achieve this simple XO (note there is a 2.2uF for the RAAL that is part of the raw FRD so not shown):


I built this prototype XO using parts from my crossover development kit and Wago connectors in 10 minutes (highly recommended to have a complete kit of all major inductor/cap/resistor values on hand - a kit like this costs under $200 and allows what if XO's to be tried out and verified instantly without waiting 3-5 days for parts to come in):


And here is how the predicted (blue) and measured response (orange) looks:


This is the predicted Impedance for the system (note that as an open baffle there is only one peak on the woofer rather than two for a vented alignment - another reason to use a TL is to really flatten the high impedance peak here):


Here is the measured data at higher resolution 1/48th octave smoothing:


Here is the measured acoustical phase:


Here is the measured step response:


The measurements all match the simulations on Xsim almost perfectly. I am very confident that the crossover simulator is working well and I can refine this even further. This is XO1 and looks and sounds unbelievably good.

You know a new speaker sounds exceptional when you forgo sleep to listen to reference tracks in the wee hours of the night. I listened to this list and was very impressed. I used my 10F/RS225 TL on the left channel to help balance out the bass to give some weight to the bass that will come later once I put the baffle on a TL cabinet. But for now, the PTT6.5 and RAAL combo sound great as an OB. The combo provides a lifellike realism with lots detail, yet they are not harsh or fatiguing. I feel a sense of emotion from the performance really coming through. A beautiful sounding combo.

Playlist:
Yuri Honing Trio "Walking on the Moon"
Suzanne Vega "Rosemary"
Natalie Merchant "Maggie Said"
Ahmad Jamal "Autumn Rain"
Omer Avital "Maroc"
Circuit Bent "Orchestrality"
Eagles "Hotel California"
Steely Dan "Hey Nineteen"
Metallica "Enter Sandman"
Anne Bisson "September in Montreal"
Chris Brubeck "In Your Own Sweet Way"
The Who "See Mee Feel Me Listening to You"
Gordon Goodwin's Big Phat Band "Garaje Gato"
Norah Jones "Burn"

All I can say is that this combo really shines and shows a marriage made in heaven for these two drivers. These RAALs are on loan, and I am seriously thinking to myself that I will need to get myself a pair. 🙂

Is anyone familiar with the 6L6GC/KT-66 push pull amp from his book Vacuum Tube Amplifier Basics? I don't want to use the copyrighted schematic here so I'm hoping someone will be familiar with it. It looks pretty simple; but I'm wondering if maybe it is too simple for really good sound quality since it is from a book of "basics" and would be designed to be easy to build. Nothing fancy, cathode biased output tubes, 12AU7 for a driver/splitter

thanks,

I have been upgrading speaker wire from 14awg to 11awg, once I got the long wires ran from Amp to external x-overs,
I also upgraded the" sda interconnect wire" to 11 awg also, and the speaker wires from x-over to SDA speakers from 14
to 11awg also.
I ran out of connectors so the "stereo mid-woofers are still 14awg.
Waiting for more connectors in mail.
Listening , the speakers have never sounded so good.
I might not upgrade the Mid-woofer wires from 14 to 11awg.
I advise you to try this wiring scheme, of SDA input having less resistance than
the mid woofers.
Amazing.......

I've a couple of 13" woofers that I'm planning on building into a sealed box. I've done the TH measurements and calculated that a box of around 180 litres is the right ball park for a Qtc of 0.707. The EPB suggests a sealed box only. Large, I know...

Given that stuffing has an effect on Qtc would it be correct to build a smaller box of say 150 litres and progressively add stuffing and keep measuring until 0.707 is reached?

Box construction I'm thinking of thin-wall with bitumen pads, and acoustic foam (egg-crate) to reduce standing waves.

Stuffing I'm thinking old fabric based carpet underlay (not the dimpled rubber stuff) as I've got lots - or alternatively wool - except I'll have to wash and card the fleeces and that'll take many, many hours.

Am I on the right lines here?

I have an opportunity to listen to a closed enclosure bass-loading system with Qtc of 0.5. And, I do badly like it. I wish to build my four-way floor-standing loudspeakers project with this specification. My project is originally planned to be passive radiator system where the passive drivers are already arrived in the stock. Yet, the cabinets haven’t been designed and constructed. Thus, I’m curious to know whether it is possible to create a passive radiator system whose response or alignment resembles that of the closed enclosure with Q of 0.5 system. Has anyone ever tried it? If so, could you please instruct, or better provide the procedure, how to achieve it?

What's on YOUR bench?

Gentlemen, my living-room amplifier (Audio Agile Step AMP, the company "Audio Agile" does no longer exist and I have not been able
to source the amplifiers schematic for repair) passed away 2 month ago, and I need a replacement for it.

I do not like to use my SYMASYM as replacement.
The SYMASYM has been the "working-horse" for all of my projects and works perfectly with them.

Nor do I want and use any of Mr. Nelson Pass' amplifiers.
His amplifiers (I have built his A40, F5, ACA) are too weak (may I therefore call them "CORONA amplifiers" - without being put into the bin?)
to ventilate my speakers (f.e.: KAPPA Infinity 600).

I have remembered Prof. Nelson Pass' amplifier (Release 4.5) to sound very well and have done a layout of my own.
Image1 shows the schematic; Image2 shows the layout.

I have the needed MPSA06, MPSA56, 2N3439 and 2N5416 at hand for 5 pairs of the Leach_AMP PCBs.

I will use NJL0281DG / NJL0302DG with integrated thermal diodes as output transistors.
MOUSER does not currently offer the NJL. But ARROW does!

I have not yet ordered anything from ARROW. Is it a trustworthy company?
If so: I will order 25 pcs. of NJL0281DG/NJL0302DG each and match them (as well as the MPSA transistors) for you.

The PCB size is 228 x 79 mm.
The price for 1 PCB, 6xMPSA06, 5xMPSA56, 2x2N3439 and 2x2N5416 is 15€. A pair of PCBs will then cost 30€ (shipping cost not included).
2 pairs of the Leach AMP PCBs are already spoken for.

Are there any 3 (even more?) of you, who want to build this amplifier?
Give me a PM then.

Best regards - Rudi_Ratlos

Hi Guys, am looking for one of these, does anyone know of one please?

SOLD --- SOLD --- SOLD

My_Ref amps have been sold, so no longer available!

It’s time for a clear out! So, for sale are the following items, fully assembled and completed, and sounding great! Built by me as I progressed through my DIY audiophile journey, now surplus to my needs.

My_Ref Fremen Edition power amplifier, version 1.8 pcb’s
Built exactly as per official build guide as 2 x mono-blocks, with cost being no object. All ‘best’ components installed, including all recommended audiophile upgrades completed:
I/C’s: LM318 Op Amp, LM3886 Main Amp
Caps: Nichicon, Elna Cerafine, Mundorf MCap Supreme, Amtrans
Resistors: Vishay Dale, Charcroft Z-Foils, Mundorf MResist Ultra
Transformers: 2 x 240vac, 25vdc, 225VA
Enclosures: 2 x Galaxy Maggiorato GX288 (230 x 280), black with silver front panels
RCA + Speaker Posts: Hifi Collective gold plated
Front LED indicator

… and the result is a terrific sounding little amplifier! Total build cost was in the region of £700, but I would be happy with any sensible offers - say £300?

Some images attached, reasonable offers considered!

If you'd like any more info, please drop me a PM.

(Note - LM3886 Gainclone power amplifier is sold, so I've edited this post to remove the details as no longer relevant)

Cambridge Audio CXN V2 network player in perfect condition, in original box. Free shipping to continental US.

Asking $500.

VG

I am attempting to determine whether some JFETS I have on hand are behaving properly.
I breadboarded this circuit (I reversed battery polarity for P-channel JFETs):

And got these results (horizontal axis is volts and vertical axis is milliamps):

One P channel device is most certainly dead: 1-2 and 1-1 isn't linear.
But are the others alright?

Selling my fostex 208 NS drivers that were originally in my kirishima cabinets.

£300 collection only, sorry no packaging.
Selling / sold off my complete system.

Let me know if you want anymore pics etc.

Cheers all.

Here is some information on an MFB speaker I worked on and eventually made a couple of samples of for my own use back in the early 80s. At some point I hope to analyze it a bit with newer tools and share that information. Hopefully it will be of interest to at least a few. Frankly, I don't think that this will provide any new information for those here who are technically inclined and have experimented with the technology. There are certainly people here with a much better handle on electronics and control theory than I have. But it provides another example of an acceleration feedback system to read about. 🙂

I haven't worked on this sort of thing since that time but I find myself interested in giving it another go. But I have a lot to learn about the tools being used today for this sort of development. I may need some guidance on that.

But anyways, first a bit of history. Back around 1979, I had what I thought was the brand new, never-before tried and supremely brilliant idea of fixing the non-linearities of a low frequency loudspeaker with some sort of negative feedback. I constructed a very simple op amp adder feedback circuit (pushing the limit of my technical knowledge to the extreme) and fed back a position signal derived from a lamp, LDR and light blocking card attached to the back of the speaker cone to the preamp signal. Well, it worked right away and was stable. What's so hard about this! For a moment, I thought I had solved all the world's problems with accurate low frequency reproduction.

Then reality set in.

I knew it was working because I could push hard on the cone with my fingers and the amplifier was pushing back. If I pushed hard enough, the over-current protection on the amplifier would trip. But I soon discovered it only worked at very low frequencies. And as I rationalized later, it probably was only stable due to an extremely limited bandwidth of the sensor.

So after some trips to the University library, I realized there were already successful implementations of motion feedback using both velocity-sensing coil and accelerometer feedback methods. I discovered the 1968 Philips paper by Klaassen and Koning and discovered an MFB speaker had already been produced in Canada by PSB Speakers. This was the Beta II which employed a Philips MFB driver and, if memory serves, it had been in production since the mid 70's. In pursuit of a B.Eng.Sc. degree I needed a 4th year project so this became the "Motional Feedback Speaker" where I would try to develop a version on my own. Fortunately, I had access to lab equipment and a very good lab technician who frankly ran rings around me on the electronics side of things. And Paul Barton graciously forwarded additional technical articles that were not in the library. Without these, I seriously doubt a good result would have been possible.

I don't have any pictures of the original prototype, but attached is a pic taken recently of one of the two speakers that were built for my own use back in 1982 along with the MFB control box for a stereo pair. Note the drivers are P/N AD80671/MFB which were round versions of the original octagonal driver P/N AD8067/MFB. I think these were available in the later years the MFB drivers were produced. You could just order these drivers and 12" versions directly from a Philips distributor at the time.

Hi
So long time owner of the Marantz MM-8003 multi channel power amp. Had it from new and even if I have since purchased other amps I still use it to drive my rear channels in bi-amp mode. Now the issue is that I have had a re-occurring fault that have forced me to send it in for repair 3 times - every time with the same protection fault error.
Guess what - have now happened again. I have the service manual but honestly no direct clues except for measuring the whole amp.
I am guessing this is due to a component that should be replaced with a better version so that the error would not happen again. But, no clue available from the previous places that have repaired in the past and I honestly are getting a bit tired of paying for this.
So, does anyone have a clue to where this error is located? The amp will start but stop in protection mode with a fast blinking LED.
Would really appreciate if someone could give me a clue.. I know how to solder but not really equipped to do a complete fault finding (Yes, have measuring tools, multi meters etc. but still...)
THX

Hi, I need help in troubleshhooting my Magnepans 1.7i!

They emmit a kazoo like sound, when playing Trumpets or womens Voices.
It sounds distorted and only affects a small high frequency range.
It's not so much dependent on volume, even at low volumes it's recognizable.
Visualy the foils look ok. The alu-traces are OK and completly glued to the foil.
There are three dots in the middle of the membran, to spread resonances.
I suspect, there's a rubber between the discs that has hardened over time.

The speakers are 6 years old.

Did somebody experience a similar problem?
I ruled out the other components in the chain.
It's definitly the speaker.

What's your opinion?

Thanks
Olaf

Hi all,

I am in a process of rebuilding some old gear, namely a TAG Mclaren processor with new capacitors as the current ones are reaching the 15y old mark. This is done for quite a lot of folks and apparently is sufficient to fix some error codes / glitches that the processor exhibits in a device of this age.

Meanwhile, i was wondering if it would be sensible to "recap" the AKSA power amps after 2 decades of good old service too ? My eldest amps from Hugh are the AKSA 100N, dont remember the exact date but probably getting to 20 years now.....that is a lot ....wow...time flies.

Does it make sense to touch it, if no problem seem to be happening ?
Is there a % reduction in say power supply reservoir capacity with a 20 year old psu ? TAG fans seem to refer that a 10 year old amp, probably is at 70% capacity and this can be noticed in "midrange and bass". Does this make any sense ?

I honestly cant say if anything sounds different from 20y ago...as my memory is not THAT good. 😀

Food for thought and discussion 🙂
SAF

I am selling my trusted Audio Precision System One. Everything is working, and the device has been used less than 50 hours since last check. Good condition.

Old school top of the line dedicated audio measuring system.

The AP comes with:

• Rack mounts Currently not mounted in the AP (See picture).
• AES17 measurement filter PCB. Currently not mounted in the AP (See picture). Only used approx 20 hours. Cost is approx 200 USD.
• USB adapter for AP System One/Two. This makes it possible to run the AP from a modern computer without the parallel port. Only used for approx 50 hours. Cost 290 USD. https://www.s1usb.com/

Make me an offer 🙂

I stumbled over a decription to build a hybrid amp "br398 mostube" from brinck in denmark.

in the decription there is a dual triode "EV21" but i cannot find any infor about this tube.
Any hints

Can anyone recommend a repairer for Revox tuner? It is a B160.

Many thanks,

Brian

EDIT:

Also for TEAC T1 Transport!!!

I have tried everything, google, ai assistant and diy audio but I am not able to find answers to my question.

My questions,
first
in image 1 output transistor q4 is tied to r6 resistance which is part of constant current with q2.
but
in image 2 two out transistor is directly connected to rails.
what are the pro and cons of each approach.
why to chose one over another ?

second
in image one no constant current source is used with q1 while it is used in image two with q4.
what are the pro and cons of each approach.
why to chose one over another ?

third
i am looking for good resources so that i can learn how to properly bias the transistors and select optimum resistance values.
could someone put towards right direction or guide me how to calculate the current and resistance values for chosen transistors and operating voltage.

any assistance would be appreciated.
thanks and regards.

I have a 60" TV in my above garage man cave/bar that is mounted on the wall, here's a pic.




The Center channel that's in there now is a Klipsch, I think maybe a G-28 or something. Doesn't really matter as it's not very good. It's thin and fits in the space perfectly, but it sound terrible, sort of like a 1970s mini transistor radio.

So the space is almost 7" from the bottom of the TV to the top of the built in area where the electronics are, and it's 4' wide or so. I can probably get away with 3-4" deep and I can't cut back into the wall because there is a stud behind the center of the area. That stud is actually part of a truss for the structure, so I can't cut into that.

I'm thinking about trying to design a center channel speaker that would replace that klipsch. To prevent comb filtering I am considering just using a single speaker module. The idea would be to build a box in similar shape to the Klipsch so maybe 3" deep, 7" tall, and the length could be anything less than about 40" to accommodate the box volume needed. Could be a sealed box, or if we could get away with it, a ported box maybe with two ports on each side of the center speaker.

For driver choice, I might be able to get away with a 6" driver but it depends on the actual frame size and a few other factors, certainly can do a 5" or 4". I don't think there is anything below 4" that would perform better than the 4" and above drivers. For center channel, maybe there are some 4" offerings that work as well as the larger ones and that would be much easier to construct a box for. Since there is only one driver, power handling is a concern.

Since I will only buy one driver, cost is not an overriding concern but I would like to keep it below $200, although if there was something that was far superior to the rest, maybe I could be convinced. Thus far, I have looked at the following potential driver candidates.
Markaudio - chr90, alpair 10.3, pluvia 11, Pluvia 7HD - The Pluvia 11 looks nice, but it would be a very tight fit, so not sure it would work.
Foxtex - FW108HS, FF165WK, FF125WK, FF105WK. The FF165Wk would also be a very tight fit.
Scanspeak - 10F/8414G-10
Seas - Prestige FU10RB H1600

So, a few questions.

1. Is this just a stupid idea? Maybe I cannot do any better than the Klipsch "70s transistor radio" sound! I sure hope that's not the case.
2. Any opinions on driver selection? Not limited to the ones I have looked at, I'm totally open to any driver.
3. Any opinions on Sealed vs Ported design?
4. Has this idea already been done? I've searched diyaudio but I couldn't find anything. I would have thought this to be a common issue and was surprised I didn't find any other threads, maybe I'm just not good at searching.

Thanks.

Hello, maybe someone have a controller schematic and .hex file for PCM1792A software control?
I am interesting a PCM/DSD switch function.
Ready to buy it.

Hello to all diyAudio users!
Selling my Hi-End CD-Tuner Alpine F1 Status CDA-7990J, for Japanese domestic market. It is brand new, complete factory set with box. Tested to make sure it works. It has not been used or installed. It was purchased by me from Japan at the time. But never had a chance to install it. Stored carefully, in a box. These are rare nowadays.

I'll give it to you for 2000$.
Experience in shipments is available, so I will send around the world.
Sending from Latvia, as I live here.
+37125973099 whatsapp

Hi All

Just picked up a pair of Celestion Ditton 551 (1979)and managed to repair a tweeter and replace both blown 500mA
fuses. I have listened to them a bit using my Sansui 250 which is not a very high power tube amp. (10-15W a side?)
They sound great turned up about 1/2 way, but the bass response is not as powerful as I would imagine.
I have no previous experience with these speakers and wonder if it's just a characteristic of them
when not driven very hard or the crossovers need recapping for optimum bass?
I visually checked 1 cross-over and it looked original with no swelling caps and resistors measured almost within tolerance.
I really wanted to avoid recapping at this stage as:
They sound pretty good to my ears except bass a little underwhelming.
I am refinishing cabs and grille cloth (hands are full)
It's a real pain to pop out the woofers to get at crossovers and risk damaging something else.





So I was hoping some people who are familiar with these speakers may shed some light.
Would be much appreciated.
Thanks Rich