IMAX Sonics Speakers

Does anyone know the theory behind the speakers used in IMAX cinemas? I know they are made by Sonics and are designed to simulate a point source. What I want is some information on how such a layout works. The subs used are a massive bank of subs that face into a slot, why? I have included a couple of pictures of their speakers so you can see what I am talking about.

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Need Help Identifying a Hammond Power Transformer Part Number

Please help me identify the part number on this power transformer. The transformer is on my Single Ended Triode tube amplifier was physically damaged and the bell end needs replacement. Not sure if the transformer still works. It will be tested later. The entire transformer may require replacement. I have emailed Hammond Mfg. and they informed me that they need the part number to determine if any or all can be replaced.

The transformer is from a: Welborne Labs Laurel II SET 300B monoblock amplifier (not the Laurel IIX, although they may be the same).

- Hammond custom power transformer: 350-0-350-5-6.3, 120Vac / 60Hz, Classic Design, Manufacture date: 1994/1995. Thanks.

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A particular LM317HV regulator

Hello,
talking to someone I know on the Bay I found out that, among other things, he sells a HV pcb as shown in the schematic,
To my question if it's some sort of Maida regulator he said no, nor a multiplier (until now I hadn't seen a LM317HV regulated by zeners).
He said it was designated by a technician friend of his. I was wondering if there is someone more expert than me who can tell me about the reliability of the circuit, possibly to be used for a preamp. Thank you

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Kenwood KA 601 Mute attenuator fail...

Hi, I have noticed that this mute attenuator switch fails and produces a hum in the left channel after a while and after switching it hundred times and spray ...
I probably need to take it apart and polish the contacts...
And I thought because I dont need this gimmick I maybe should just bypass the switch ...
Has somebody done this? I can solder... 🙂
Chris

help: B+ differences between monoblocks

Hi everyone, hope all is well. My monoblocks have been performing well until this afternoon. The Right channel plays louder than the Left. So, I started measuring and here is what I found:

LeftRight
B+ @ Rectifier Vdc355376
Ua @ driver Vdc314367
Bias @ driver Vdc3.653.86
Rectifier filament Vac4.024.19
driver filament Vdc4.714.77

I tried switching the driver tubes, same issues with the LEFT channel being lower B+ and Ua. Then I tried switching the driver tubes, same issue with the LEFT channel being lower B+ and Ua. So, the issue stays with the amp and not with the tubes.

As a side not, B+ on the output tube is the same for both amps, so the output circuit is behaving. The output has its own power supply. So, this leads me to believe that the driver power supply is where we have an issue. Schematic attached.

Thoughts?

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For Sale First Watt / Nelson Pass / Pass Labs / Passworks - BA3 or BBA3 Boards (BA-3 / BBA-3)

Hi all,

Since I will not be building a second set of these classy power amplifiers, I am offering two sets of the required circuit boards here.

IMG_6466D.JPG


Appropriate documentation / BOM / assembly plan is clearly available and will sen via email. ;-)

Good description and tips on assembly
As BA-3: https://www.diyaudio.com/community/...-illustrated-build-guide.258301/#post-3973243
As BBA-3: https://www.diyaudio.com/community/threads/burning-amp-ba-3b-balanced.201281/#post-2739404

So you could build 2 x balanced (1 x mono each) or 2 x stereo.

Costs?
  • Stereo set 70€
  • Symmetrical set = 130€

Shipping to Germany (without islands) as a parcel: 8€.

For other countries / options just ask.

Audio Research SP6B repair advice needed

Hi all. It's been awhile. Had a few health problems, so was out of it for almost a year...
Not sure I'm in the right forum - got this nice SP6B preamp, found a dead diode, burnt resistor and a shorted cap in power supply, replaced. Brought it up on variac - all is nice: current draw is about 350 mA, HV and LV all check out. But when I plug it in directly, and turn it on - boom! - fuses blow one after another. From what I was able to catch on my digital ampermeter, it draws a lot on turn-on, like 5 or 6 amps. there must be a problem somewhere in power supply. Any suggestions appreciated. Thank you.

Foster E100T10 ribbons - what quality?

I bought a pair of old speaker boxes with the plan of refitting them with a FR single driver. (The volume was right.)

The woofers and mids were shot - rotted foam.

There are however, two (2) Foster E100T10 ribbon tweeters, apparently in good condition.

I have found the tech specs, here: www.allenorgan.com/forsale/fosterWithOutFacePlate.pdf

What sort of quality were these ribbon units? Is it worth using them as a basis for another project?

Opinion?

Doug

Artificial Intelligence to design a 300B Amp?

I just had the following conversation with Elon Musk's AI, chatgpt, talking shop about 300B drivers and operating points. I've used this at work to get quick answers, but today I'd thought I'd see how much he knows about tubes. Pretty scary and pretty handy for looking up stuff. Here is some of the conversation sample:

New chat
Optimal 300B Operating Point.


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Richard Hansen
what is the optimal operating point for a 300b vacuum tube for lowest distortion?
The optimal operating point for a 300B vacuum tube for the lowest distortion depends on various factors such as the bias voltage, grid voltage, and plate voltage. In general, to minimize distortion, the operating point should be set at a point where the tube is operating in its linear region.

One approach to finding the optimal operating point is to use a load line analysis, which involves plotting the tube's plate characteristic curve and the load line of the output transformer on the same graph. The intersection of the two curves represents the operating point.

In practice, the optimal operating point for a 300B vacuum tube for lowest distortion may vary depending on the specific amplifier circuit, the type of music being played, and personal preference. It is often a matter of experimentation and fine-tuning to find the optimal operating point that provides the desired sound quality. It's best to consult the tube datasheet or a knowledgeable technician for guidance on specific parameters.




Richard Hansen
rank the various types of driver tubes that are used with the 300b tube
The choice of driver tube for a 300B tube amplifier is often a matter of personal preference and can depend on the specific amplifier circuit and the desired sound quality. However, here is a general ranking of the various types of driver tubes that are commonly used with the 300B tube:

6SN7: The 6SN7 is a dual-triode tube that is commonly used as a driver tube for the 300B. It has a high gain and low noise, and its sound quality is often described as warm, smooth, and detailed.

5687: The 5687 is a high-transconductance dual-triode tube that is often used as a driver tube for the 300B. It has a low distortion and high linearity, which makes it suitable for high-fidelity applications.

6SL7: The 6SL7 is a dual-triode tube that is sometimes used as a driver tube for the 300B. It has a lower gain than the 6SN7 but can provide a detailed and transparent sound.

5842: The 5842 is a high-gain dual-triode tube that is sometimes used as a driver tube for the 300B. It has a small size, low power consumption, and low noise, which makes it suitable for low-power applications.

ECC82/12AU7: The ECC82/12AU7 is a dual-triode tube that is sometimes used as a driver tube for the 300B. It has a medium gain and low noise, but its sound quality may not be as detailed or dynamic as some of the other options on this list.

Note that this is not an exhaustive list, and there may be other driver tubes that are suitable for use with the 300B tube depending on the specific amplifier circuit and application. It's always best to consult the amplifier's manual or a knowledgeable technician for specific recommendations.




Richard Hansen
this answer is incorrect. the 6sl7 has a higher gain than the 6sn7.
You are correct, I apologize for the mistake in my previous answer. The 6SL7 does indeed have a higher gain than the 6SN7. Therefore, I would like to update my ranking of the various types of driver tubes that are commonly used with the 300B tube as follows:

6SN7: The 6SN7 is a dual-triode tube that is commonly used as a driver tube for the 300B. It has a warm, smooth, and detailed sound quality, making it a popular choice for audiophiles.

5687: The 5687 is a high-transconductance dual-triode tube that is often used as a driver tube for the 300B. It has a low distortion and high linearity, which makes it suitable for high-fidelity applications.

6SL7: The 6SL7 is a dual-triode tube that is sometimes used as a driver tube for the 300B. It has a higher gain than the 6SN7 and can provide a detailed and transparent sound.

5842: The 5842 is a high-gain dual-triode tube that is sometimes used as a driver tube for the 300B. It has a small size, low power consumption, and low noise, which makes it suitable for low-power applications.

ECC82/12AU7: The ECC82/12AU7 is a dual-triode tube that is sometimes used as a driver tube for the 300B. It has a medium gain and low noise, but its sound quality may not be as detailed or dynamic as some of the other options on this list.

I hope this updated ranking is more accurate and helpful. Thank you for bringing the error to my attention.




Richard Hansen
would the Russian tube called 6S45P work well as a 300B driver?
The Russian 6S45P tube is a small signal pentode that is commonly used in audio amplifiers as a driver or preamp tube. While it is not one of the most popular driver tube options for the 300B, it could potentially work well depending on the specific amplifier circuit and personal preference.

The 6S45P has a high transconductance and low internal capacitance, which makes it suitable for driving high-current loads such as the 300B output tubes. It also has a relatively high plate voltage rating of 250V, which is within the range of the typical operating voltage for a 300B amplifier.

However, it's important to note that the 6S45P has a different pinout and different operating characteristics compared to the more commonly used driver tubes such as the 6SN7 or 5687. Therefore, using the 6S45P as a driver tube for the 300B may require modifications to the amplifier circuit and careful adjustment of the bias and operating points.

Ultimately, whether the 6S45P is a good choice as a driver tube for the 300B will depend on a variety of factors including the specific amplifier circuit, personal preference, and the desired sound quality. It's always best to consult the amplifier's manual or a knowledgeable technician for specific recommendations.





ChatGPT Mar 23 Version. Free Research Preview. ChatGPT may produce inaccurate information about people, places, or facts.
ChatGPT

Does BL affect the smoothness of a horn?

You guys have seen a bunch of the Unity horn projects I've built.

I tend to use cheap drivers, and those cheap drivers frequently have low BL.

Does high BL smooth out the response?

Some folks have been publishing hornresp sims of midbass horns, and I noticed that when they're using high BL prosound drivers, the response curve in the passband is epically smooth, compared to the sims I get for my cheap $10 and $20 midbasses.

I don't have many high BL drivers in my collection, but here's a Unity horn I made with a B&C 8" midbass:

71rL2tX.jpg


IKV53s5.png


Thread is here: https://www.diyaudio.com/community/threads/bend-it-like-bateman.378855/

For comparison's sake, here's a Unity horn I made last month using four Parts Express ND64-16s, which are low BL:

img_20230401_183838-jpg.1161637


2023-03-25-12_09_48-overlays-png.1157776


Thread is here: https://www.diyaudio.com/community/threads/nehalem.396920/page-2
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Audiopipe 30001D

On the board with the power supply the drives don't look right at the gate. Put on the pins on the back of the card they are perfectly fine. Could the driver card still be bad? There is 5v across pins 1 and 5 of the 6n137s and square wave in pins 6,7,11 and 12 on the driver card. Between the gates and source it reads
Q1- Q4=104
Q5-Q8=9.5k
On the back of the card the voltages are
Pin1= .01
Pin2=.02
Pin3= .01
Pin4=-11.4
Pin5=11.4
Pin6=2.4
Pin7=2.4
Pin8=0.2
Pin9=5
Pin10=2.3
Pin11=2.3

This is the drive on Q1-Q420230420_115916.jpg

This is the drive on Q5-Q820230420_115904.jpg

Best Sounding ChipAmp?

Folks:

I'd like to build a small integrated amplifier for one of my nieces. I've built quite a few LM3875 and LM3886 amps and could do so again, but wonder whether better-sounding options are readily available. To be clear, by "better-sounding" I mean better extension and a greater sense of the performances' spatial characteristics. More air between the performers would be nice, too. Although I'd prefer to populate pcbs myself, I'm open to partially-built solutions. My preference is to include a linear power supply and not use an SMPS.

So, should I pursue a tried-and-true LM38XX amp or head off in a new direction?

Thanks in advance for your considered advice!

Regards,
Scott

PCBs of layouts of Ampslab's C300 amplifier

I am working on building a stereo amplifier using the C300 amplifier of Michael Chua of Ampslab. It is a Class AB BJT-based stereo amplifier capable of 300 watts per channel. I have the PCB's on my github at

GitHub - profdc9/PowerAmpAudio: Power Amplifier based on Michael Chua's C300 amplifier

You can read about the C300 at

https://ampslab.com/c300.htm
c200 Power Amplifier @ AmpsLab

There are four PCBs in the project so far:

1. C300 amplifier PCB
2. Power supply rectifier and filter (low pass filters and common-mode chokes)
3. Soft start PCB for toroidal transformer and capacitor bank based on DIY audio's soft start
4. Balanced XLR to unbalanced input for the amplifier (based on THAT1200 / THAT1240 / SSM2141).

The schematics and gerbers are all there as well as BOMs with component part numbers mostly from LCSC.com , with a few digikey and Mouser parts as well. I release my projects under the Creative Commons license. The PCBs can be made at PCB factory like JLCPCB or PCBWay; I am using JLCPCB.

We have ordered all of the stuff and are going to photodocument the build. As an example I have a screenshot of the PCB. Check out the archive. I also have other many projects I have created on my github (but mostly not audio equipment related).

Dan

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FS: Earthworks M30BX precision measurement microphone

THIS HAS BEEN SOLD.

Selling my Earthworks M30BX precision measurement microphone. The BX option is battery powered and has very low noise. A removable XLR to RCA converter is also included so that you can connect the mic via an RCA input on your audio interface, if desired. You can always use it via a balanced mic cable and no phantom power is needed. MFG info here:
https://www.earthworksaudio.com/wp-content/uploads/2017/08/Earthworks-M30BX-Manual.pdf

When I purchased this mic in about 2016 I had Earthworks do an extended calibration on it that is valid from 0.1Hz to 80kHz. This was so that I could get reliable measurement data on tweeters up to 80k. I will provide the calibration file to the buyer.

I use other mics for my routine measurements the Earthworks has been used sparingly and always stored in a cool, dry place in its case.

I have the original case and will pack with padding for safe transit. I'm happy to provide pics upon request.

Filtering circuit to eliminate RPM-dependent whine in car audio system

I have an after-market navigation/audio receiver wired to my cars 12v system, with audio connected to my cars built-in AUX jack. When no audio is playing, I can hear a high-pitched whine, which changes with engine speed. I know this is a common issue with car audio, and that one can build a filter to eliminate it. I'm wondering what that filter should consist of, so I can build a good one to insert into system (I assume into the power line going to the receiver?)

Methods to widen top octave dispersion?

A few questions:
What is an optimal listening window, flat with on axis, or a slight decrease down to say -2dB at 20kHz?

What methods can be used to widen dispersion from 10-20kHz, and or to flatten the horizontal listening window (0-30°) and vertical listening window (0-10°). And can these methods apply to tweeter waveguides, although any other methods would also be interesting.

Panasonic 3 CD tray won't open SL-DH66

I have a Panasonic Stereo Audio System with Compact Disc Changer SL-DH66. It is circa 1995. It has worked like a champ until I moved it with 3 cds in the tray.


When I turned it on after the move, the tray would try to open, at least I heard the noise, but it seems obstructed.

From what i have been able to glean from videos, there may be an o-ring somewhere that slipped or broke. but i can't figure out how to access it. I have the unit apart and don't want to break it further. can't decide if access to this o-ring is under the 3 cd tray or from bottom of unit.

Maybe my theory is wrong. Looking to repair the open/close function of the cd tray.

BPI 3000c Distortion Analyzer Auto-Null Problem

I have been repairing a BPI 3000c auto-nulling distortion analyzer and have had to replace quite a few parts to get it working. Overall, things are looking pretty good but I’m having problems with the auto-nulling circuit for frequencies above 7 kHz. The unit should be able to read down to .005% distortion from 20-20,000 Hz. It now works to spec below 7 kHz but won't go below 2% at 20 kHz.

The auto-nulling has an auto-tuning notch filter circuit and an auto-gain circuit both based on optocouplers. Although they both work at lower frequencies, the gain setting reaches it limit on higher frequencies and so about 2% “distortion” remains in the signal after auto-nulling. The remaining waveform significantly shows the fundamental wave. Something is limiting the ability of the circuit to null correctly above 7 kHz. The tuning component appears to be working correctly but the gain circuit runs out of gas before the waveform is fully nulled.

I have spent quite a bit of time on this problem and haven’t figured it out. I have schematics and can explain the circuit topology fairly well but obviously I have some limits to my understanding of how it works.

Does anybody have familiarity with this unit?

Thank you,

John

Another look at how to measure the Baby Huey circuit

And what’s that resistance link across the middle doing? Does it help?

In this simulation the triodes are represented as Inverting Voltage Controlled Voltage Generators of voltage mu in series with a resistance of rp, their plate resistance.

And pentodes are represented as Voltage Controlled Current Generators of Gm (mA / V) in parallel with their plate resistance rp.

The switch ‘D’ sets no differential resistance or 100K. The switch ‘H’ controls the current in the middle link.

In Test A1 there is no differential current on the first stage, the voltages on the plates are very different. With no drive at all where is the voltage on the lower plate coming from? Checking the signal on the output stage plates they are equal. The OPT forces an equal but opposite voltage on the opposite plate. That gets fed back thru the resistive network resulting in a signal at the lower tube plate even tho no drive on its grid.

Checking the AC currents in the PP output stage, they are very different. It appears that inserting small resisters in their cathode leads to common would be a good addition. And AC measurements can be made there.

In Test A2 the switch H is closed, the circuit balance gets worse. But the voltages at the at the ends of the OPT still look OK. The currents are very different. The cross link in this case didn’t help at all.

In Test A3 the switch D connects a degree of differential coupling & the balance in the circuit improves. And the current balance in the OPT also improves.

In Test A4 the switch H connects the cross link & further improvement results.

Conclusion One- The Baby Huey cross link provides a degree of improvement in this circuit.

Conclusion Two- Checking the AC signal for voltage balance may not lead to a solution if there are problems. 😀

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Valvo E 88 CC vs. ECC88

Hi.

I'm building a Gyraf Oultec tube Q.

Circuit is designed for a ECC88 tube.

I have com a across a Valvo E88CC tube, but not sure if this will work.

I have read that the difference is in the amp current for filament. both have a voltage of 6.3V

Some datasheets for E88CC states the current for filament is 300 mA wheres others says 365 mA.

Current for ECC88 is 365 mA.

- Best A

Sennheiser Momentum $ or ???

I am looking into stepping up my headphone system and am in the market for new cans. I have a pair of cheap Sound Core Life Q20 cans (which actually sound much better than I expected) and Bose QC 35 cans. I'm looking at the Sennheiser Momentum 4s, but I'm hoping someone here can help me with a question. The Momentums have a lot of bells and whistles. Are they worthwhile? I want noise canceling, closed-back, over-the-ear, and a wired connection, so is there a different pair in the $300 range that would be better? The Momentums receive great reviews, but I want to make sure, as much as possible, I'm getting the best bang for my buck.
I also use a FiiO DAC and a JS Labs Cmoy amp.
Thanks,
Mike

HK Lucas quadamp question

Hi there. I'm new on this forum but I'm finding it hard to locate info on the web. I have been repairing an HK Lucas impact which had a fault inside the quadamp metal box. I've tracked down that problem but in the meantime my kid has fiddled with the 5dip switches in the red block. I can't recall how they were set so I'm wondering if anybody has photographed one of these to see how to set them. Any help would be very much appreciated

Switch-able Sound-base / Centre / Satellite Speaker

I changed my desktop speakers recently and was inspired when I lay them on their sides. I'm on a hybrid kick at the moment. I need a good quality sound when watching TV. I need extra oomph when enjoying music. I need serious warp power for watching movies.

Can this be wired?

Laying the Sony SS-Fe9s on their sides inspired me. Can I make a switch?

Pos 1: 4 x 3.5" woofers in a single cabinet would make an excellent sound-base for the TV (full-range, stereo),
Pos 2: (3.1) Centre woofers = centre channel. Outside woofers and tweeter: L/F and R/F.
Pos 3: (Centre-speaker) all drivers wired for mono.
I post a pic so you can use your imagination. Imagine it's a single cabinet.

C-Speaker.jpg

Breaking up with the Raspberry Pi

I'm new to this forum, usually post on tube/valves. This might be the wrong place to ask and if so, maybe someone can point me in the right direction.

With the Raspberry Pi supply situation being what it is and unlikely to improve anytime soon, what are the alternatives? Coding is not my thing, but have managed to setup two Pis, one running pCp and the other Volumio.

I recently saw a YouTube interview with the big kahuna at Raspberry Pi and he essentially stated they are supporting their commercial/industrial customers at the expense of educational and experimental users.

Are there other SBCs out there that have fairly straight forward audio implementation possible? I wouldn't likely need a HAT, just go with a USB connection to a DAC.

Thanks, Steve

Ouch! My son put live speaker wires into my DAC's RCA analog input!

My son erred and put speaker wires terminated with single banana plugs from a Hypex UCD 180 amp (powered on), into the RCA analog input and output of my Emotiva Stealth DAC which was also powered on.

I realized this and turned off all equipment. The long and thick nature of the Banana plug has stretched and damaged the width of the internal plastic section of the RCA plugs. At minimum I think I will need to replace and solder in new RCA plugs, as a test fit with an RCA cable was quite loose.

Besides messing up the RCA jacks, what other internal damage do you think this might have caused?

The DAC section still seems works fine via SPDIF in and balanced out cables, but I have yet to try the analog in/out as I am afraid to realize the results.

Upgrade Ideas EBB 150 Mosfet Module

Hi guys,

I built this simple power amp, 125w, first upgrades were changing the cheapy caps for Elna Silmic II, better power caps, hardwired input and output, hardwired dac everything is direct.
Now the only things I can think of trying next is an oversized transformer and increasing the rating of the power caps and using Mundorf M Lytic.

Can anyone suggest some other upgrades to these two modules, I cut out and bypassed the output coil but this is an older photo. The amp sounds stunning, just needs a bit more bass and low mid-range.

Thank you!

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Strange capacitor for analog oscilloscope

Hello , I have a problem with my analog oscilloscope . I want to replace the burnt capacitor of my oscilloscope, but the problem is that this capacitor is not available in a local store. writes up 0.1uf X 2x4000pf Y
.and I thought to replace with 3 capacitors. 2 are 4700pf and one is 100nf .. the problem is how exactly will I connect them? I researched the topic a bit and thought of this way in the photo with the design. if anyone knows i would appreciate it, i am also attaching the capacitor that is burned .

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Get audio from guitar pickup to be recorded do tape with minimum components possible.

Hi everybody! I think that got to the best place possible to look for help with my project.

I'm trying to build a tape delay with parts of a handheld recorder PANASONIC RQ L11.

My idea is to use just the recording heads and the motor, and would like to know what's necessary to get the signal from a guitar pickup to be recorded on the tape.

What would be the minimum circuit necessary to get the signal from the pickups to be recorded on the tape?

I want to build the circuit with as little parts as possible, because I want to mount everything inside of my guitar, so I can control the speed of the motor on the fly.

Using the actual board of the RQL11 I was able to record by soldering my input signal in place of the the mic of the recorder, but if anyone have a practical solution to put other simpler circuitry, that might just handle the signal from the guitar pickup direct to the tape, that would be perfect.

Any help will be great!

3.5-way Falcon like Baffleless Concept Speaker (some design study)

For several years I wanted to build loudspeakers based on the Falcon like Baffleless Concept Speaker designed by AmpsLab (Falcon, Falcon II, Falcon III). I recently sold my Klipsch Tangent 400, so there's an opportunity to build something new. Initially, I wanted to base the project on a Dayton RS52AN dome, but a friend convinced me that Visaton G 50 FFL would be better (easier to apply). As a partner for the G50FFL, I wanted the largest possible woofer (12" or 10"), but in turn, colleagues from this forum convinced me that a maximum of 8" woofer would be better. I chose the Visaton W200S (nice woofer good for 2-way also, 8" is good for cross with mid dome @ 800Hz, better for directivity match, should be quick enough). To help with baffle step correction and lower extension I decided to add 0.5 way and a second woofer - Visaton W250S in parallel. Lower woofer will be vented and upper woofer will closed (like in Tony Gee's speakers).
I need your help to make this concept work.
1. Is it the crossover concept from Zaph ZDT3.5 good for me (I mean the way woofers are connet in parallel)?
2. What tweeter will You recommend for Visaton G 50 FFL - crossed @ 3,5KHz (or so). I think small tweeter will be better for directivity match and closer sound center of both domes. My type is SB Acoustics SB21SDCN. Any better small tweeter for up to 50 Euro/pc?
3. Cabinet - high 90cm, 32-35cm wide and 30-32cm deep. Is it better make wider (lower frequency baffle step correction) or narrowest possible?
4. Should both woofers be as high as possible?
Visaton W250S, W200S and G 50 FFL I already have.
Thanks in advance for advice.

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Measurement for WM8978 audio codec, how to ?

Hi !

I made a custom audio development board with an esp32 microcontroller and a WM8978 audio codec.

All inputs and outputs work great but now I want to go further by measuring S/R and THD.

The datasheet of the codec gives values for SNR and THD but depending of the quality of the PCB routing I think these values may be quite different.

The question I face is how to do the measurement for my board ?

If you look at datasheet P14 (https://www.mouser.com/datasheet/2/76/WM8978_v4.5-1141768.pdf) we have lots of routing possibilities.

If I generate a pure 1KHz sine wave to feed the input and put a probe at the output to measure the added noise/distorsion by the codec and the board, I have to test it for all inputs, all outputs, and all the possible routing scenario !? Because we can have lots of different signal path I think the noise may be different for each but what is the value I put when I describe the features of my board ? 🤔

It is the first time I have to measure audio quality so I'm a bit lost.

Burson Audio OPA5 discrete+BB OPA627

For sale a pair of Burson Opa5 discrete opamps in original package and 6 x BB Opa627 opamps. I buy the bursons about 5-6 years ago for my cd player. The BB Opa627 I just found now when I have cleaning my hifi closet. I think I buy this long time ago directly by Mauser Usa. It must be more than 10 years ago. So the Bursons are also single opamps like the Opa627. The price for bursons would be 60 euro plus 4,80 euro shipping inside EU and for the Opas the price would be 15 euro/piece plus shipping or best offer. If someone will buy the whole pack, the price is 120 euro plus 4,80 euro shipping in Europe Union. Outside EU or overseas plese ask. Payment Paypal for friends.

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2SK177 replace with S2K170 - Technics SU-V8X - fet differential amp, pre drive, cascade servo pcb

A friend who knows Technics very well and has a large collection, helped me with my Technics SU-V8X. It can not set bias, at the outputs, it had high voltage across E CB and my friend said something is wrong on the amp board.

I took out all 24 transistors ( that included the 4 MosFets). The transistors seem to test fine, had some issues with C on Q315/6, however i think that was the micro clips, not making contact, so after 2 more readings C was fine under 800.

I then moved to the MosFets and followed a video online, and i never got OL( open on my meter is 1) readings, just low numbers like 148 158 on my 3.5 digit meter, so i assume they are defective?

Since 2SK117 is discontinued, by chance i went through my spares, and found my spare V4X phono pcb and found 4 2SK170 mosfets (which i hope are fine, as ive stored them in a box over the years).

Specs are very similar , voltage is lower with the 170s, and it actually appears lower noise? I tempted to try them, however will check some resistors first in the path to see if there is any defective. Only difference is VFDS -50v vs - 40v, otherwise pretty close

This might be useful thread for a reference for the parts as well, i hope.

2SK117 Product details
Low Noise Audio Amplifier Applications

• High |Yfs|: |Yfs| = 15 mS (typ.) (VDS= 10 V, VGS= 0)
• High breakdown voltage: VGDS= −50 V
• Low noise: NF = 1.0dB (typ.)
(VDS= 10 V, ID= 0.5 mA, f = 1 kHz, RG= 1 kΩ)
• High input impedance: IGSS= −1 nA (max) (VGS= −30 V)
------------------------------
2SK170 Product details
Low Noise Audio Amplifier Applications

• Recommended for first stages of EQ and M.C. head amplifiers.
• High |Yfs|: |Yfs| = 22 mS (typ.) (VDS = 10 V, VGS = 0, IDSS = 3 mA)
• High breakdown voltage: VGDS = −40 V
• Low noise: En = 0.95 nV/Hz1/2 (typ.) (VDS = 10 V, ID = 1 mA, f = 1 kHz)
• High input impedance: IGSS = −1 nA (max) (VGS = −30 V)

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Fet differential amps Q301-304.

(if Mods think it suits the part section - please move it there, as i was not sure which of the two this belonged thanks Sam )

Crown MA 5000vz and 50002vz

Hey everyone, I have a question to anyone with knowledge about crown's 5000vz n 5002vz
Is there any difference between these two?
I hear the 5002vz does'nt preform as good as the 5000vz, not sure if that true, that why i turned here to the professionals, and also
are spare parts hard to located for these.


I tried to loacted a guy on this site who's name is "OMNIFEX" but there wasn't any luck, he seemed to know alot about these amps.

bass reflex vs double chamber reflex (ABC/DCR and DCAAV)

I would like to know if anyone has compared the systems in the figure (and possibly also the load n ° 15 type B6 by Thieele) can tell me the disadvantages and advantages of each with evidence for the aspect of impulse response or transients (also with respect to a closed case), beyond the frequency response in cutoff frequency (F3).

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Cathode voltage

Hello, I am new to this tube stuff and I’m reading a book “Design and construction of tube amplifiers” by Robert Megantz.
I understand most of it at this point but there is one item he doesn’t explain well.

In this example he chose a tube, and an operating point and chose a -1.1v grid to cathode voltage. That all makes sense to me.
He then goes on to say that since -1.1v is the desired grid-to-cathode voltage, the cathode voltage should be 1.1v.
He doesn’t explain why the cathode voltage should be 1.1v. Where did he come up with the 1.1v?
I have attached the page, and highlighted the “1.1v” section I am referring to.

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For sale: 4 used Peerless 830452 10" XLS Subwoofers: $50 each, includes shipping

I have 4 used Peerless 830452 10" XLS Subwoofers that I want to sell. The price is $50 each and includes USPS flat rate shipping to 48 US states (no HI, AK). These subwoofers have been sitting on a shelf in my garage for at least 5 years. They were used in an open baffle project that I took apart.
Four subwoofers.jpg
Subwoofer label.jpg
Subwoofer part number.jpg

Attachments

My E5 Class A hifi headphone amp

Hello all,
I design three headphone amps: E3, E4, E5

E4 is the upgrade version of E3, E5 is the upgrade version of E4, E5 sounds more pure and natural. And better performance in the heat sink and protection.

They own different characteristics. (E3 refer to the beyerdynamic A1 headphone, E4 refer to the JC2 dual differential FET input construction, E5 using Marantz HDAM input structure)
Some audiophiles in my domestic discuss these headphone amps, they like the E5 best.

Here are the pictures of E5 headphone amp, work on class A.

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For Sale Firstwatt F4 complete kit with high quality parts

Hello dear diyaudio friends

I have a complete brand new kit, consisting of four F4 channels for a balanced mono construction. Everything is included, already partly assembled. The boards are from an older group buy in the German analog forum. As said the boards are partly assembled, please check pictures for details. Q1 and Q2 are precision matched 2SK370 and 2SJ108, the power transistors are precision matched IRFP240 and IRFP9240 (Keratherm Red insulators are included). Rectifying diodes are high quality HEXFRED HFA08TB60. BIAS resistors are Mills MRA non magnetic and non inductive ones, all other ones are non magnetic Dale RNC. Power Supply resistors are green Kiwame. Electrolytic capacitors on the amp boards are all Elna Silmic, power supply caps are all Panasonic 22000uF. With each power supply, you get two tiny rectifying boards for installing the diodes. I also have two custom made high quality 500VA (230Volts/50Hz) transformers that are fully MU capsuled. One transformer weights 4.85KG.


Price for the complete amp kit: 550 Euro SOLD Only the transformers are left


I’m also willing to trade for one or more of the following items:

(Of course, I will pay difference in value)
Manufacturer sealed bags of:
  • 2SJ74-BL
  • 2SK170-GR
  • 2SJ74-GR
  • 2SK370-BL
And maybe other rare signal JFETS or dual JFETS

  • BurrBrown PCM1704-K DAC chips
  • Analog Devices MAT02 and MAT03 dual monolithic transistors
  • 2 x Starkrimson® Ultra Amp Module
  • XRK Audio RTR TPA3255 Reference Class D amplifier

Please also take a look at my other offers in the Swap Meet

Shipping:


Shipping weight will be over 10KG for the amp kit and for the chassis over 20KG.
So the costs will strongly depend on your location. I will ship anywhere in the world. Shipping costs strongly depend on the shipping method you prefer.
Of course, I will only charge the real costs, I won't charge anything for packing materials and effort. I prefer to use Deutsche Post/DHL, but you can decide which shipper and which shipping method I should use. Very secure packing by me is obvious.

As payment method I prefer PayPal for friends and family, so no extra fees will be added. Other payment methods on request. Of course personal collection of modules in Cologne (Germany) and payment in cash is also possible.

Kind Regards
Phil
IMG_1286.JPEGIMG_1287.JPEGIMG_1288.JPEGIMG_1289.JPEGIMG_1290.JPEGIMG_1291.JPEGIMG_1292.JPEGIMG_1293.JPEG

12" woofer choice for 3-way with midrange dome (Scan Speak Discovery D7608)

I am looking for a 12" (or 11") woofer for a three-way construction with a midrange dome. Woofer and midrange dome will cross at about 500-700Hz. The woofer is supposed to go down quite low, but above all to play bass with great impact. The quick, energetic with significant dynamics. The speaker must be available in Europe.

For Sale DEQX HDP-Express II speaker/room processor in the UK

DEQX HDP Express II for sale. In excellent condition. Quick summary: it's a 3-way digital active crossover, speaker equaliser, room equaliser, DAC and system preamp.

See here for a summary of its capabilities and specs: https://www.deqx.com/products/hdp-express-ii/

In conjunction with a PC, it can measure speakers or individual drivers and then create and apply correction filters to produce ruler-flat response and phase. It can apply 3-way crossovers, either conventional minimum phase or linear phase, up to 300dB per octave. You can also use it to measure your room and apply room correction. It can act as a high-end dac/preamp, with or without the other functions.

This is part of the most recent generation of DEQX processors, along with the HDP-4 and HDP-5. (These all use much newer hardware than the HDP-3 and PDC 2.6.) It has only just been discontinued recently.

These really are amazing units, and it's been the heart of my system for the last three years.

I'm the second owner. The Earthworks M23 microphone was an additional £600 option.

It has 2 analogue and 4 digital inputs, but does not have the optional USB audio input. I have a Gustard USB to spdif converter which I've used with it, and which could be included if you're interested.

DEQX units, especially this newer generation, don't come up for sale very often at all.

I'm in Glasgow, UK. Willing to ship most places. Looking for £1300 plus shipping, which I feel is a good price, especially including the Earthworks mic.

Any questions please ask.

Adcom GFA 555ii (purchased in early 1990 with no significant use in last 20 years)

The amp works and has near zero voltage at the speaker terminals when nothing is connected. I am told this is a very good sign.
I was told if the amp is faulty it can fry speakers. I still have the 802 B&W speakers that came with the amp back in the early 1990s.
Is it safe to use the amp? It works fine with the current PA speakers attached to the amp. At most I have used the amp every three or four months during the last 20 years. It blew a fuse once and I was able to replace the fuse and it continued to work OK.

Should I service the amp even if it is in good working condition?

Free Nils Frahm ticket for tonight in Montreal Place des Arts

Hello All,

For the past two weeks I've been quite sick and I am still pretty much under the weather... So unfortunately, I will not be able to go to Nils Frahm show in Montreal, an artist that I really like and was REALLY looking forward to go see him.

I'm looking to give my pair of tickets to people wanting to go, not to try to resale the tickets.

Artist : Nils Frahm
Where : Place des Arts in Montreal
Hall : Salle Wilfrid-Pelletier
Time : 8pm (tonight 2023/04/19)
Seats : J13, J15 (first floor, good seats)
Tickets will be transferred via email, as soon as I can confirm it is someone from the area.

Thanks
Do

Egg-shaped WAW idea (my latest near-field iteration)

This is the latest in an ongoing journey into new territory for me. Previous tests around the near-field theme have arrived at various (somewhat personal) conclusions:
  • My situation is indeed well suited to speakers of modest SPL positioned quite close to the listening position (say around 50cm give or take). I like this, where room effects are reduced and the neighbours don't complain as much, and yet the apparent location of instruments and vocals (etc) seem more natural to me than with headphones.
  • My first attempts with full-range drivers were very positive indeed; I'm surprised by how much I like them. However (at least with a small enclosure) it transpires that I prefer them used in a WAW configuration.
  • Speakers positioned so close can feel intrusive and also be a bit annoying for practical reasons. I've found this to be greatly improved if they are a rounded shape (rather than with corners and points), and also if they're not taking up desk-space or blocking lines of sight.
  • It is to be a bespoke creation for a slightly unusual setup, so I'd like something that looks a bit unusual too.
So... the next step will be to try egg or pear-shaped WAW speakers. I'm returning to the concept of suspending them up near ear height to leave lines of sight (and any desk, if present) in the immediate working area more free from obstruction. Something like this, but hanging or supported from behind in some way (excuse the extraordinarily crude mock-up):
28and20cm-bowl-cone-mockup_approx-12L-internal.jpg

The circles are based on (existing drivers) an alpair 5.3 and a scanspeak 15w/8530k01, which can work rather well together IMO. The mock up comprises Ikea blanda bowls in 28cm and 20cm diameters; the height is somewhat less than two stacked spheres would be, and I calculate will offer about 12Litres internal volume (before internal bracing). Probably I'd go with sealed enclosures, partly for simplicity under the circumstances and partly because I'm happy enough with how the drivers sound in them.

The alpair would want a bit less than 2Litres for a Qtc of 0.7, which would leave the 15W with sufficient for a qtc of perhaps 0.75 (depending on stuffing and braces and how the internal volume is apportioned and divided into two chambers). This will be an an active system so could be corrected in any case, but I'd just like to begin from 'approximately' suitable volumes for future flexibility.

So that is the new embryo of a plan. I don't get a lot of time off and have no workshop these days so it may take a while to realise. Combined with the complicated shape, I'll probably therefore make use of the bowls and go for a painted finish, which will allow much use of glue and filler underneath. I had considered making a mould and then using glass-fiber and resin for the walls, but that all adds to time and cost. If this works then I can always use a finished speaker as a mould later, should I want to make a fiber-glass version in the future.

Cheers,
Kev
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Masked part numbers, New era Amplifier

Guys, why are some manufacturers still masking part numbers even on designs that aren’t proprietary and the part itself are been re-engraved by them?
Is it that they are making the repair harder, or they only needs the item to be repaired by their authorized centers?
Have anyone seen the newer SoundStreams (Taramps look alike circuit)....
What could these part numbers be?;
The output marking H8 and what IC are they driven by?
Power supply FETs H1 and what PWM chip is driving them?
What is the error amp IC number?

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Is it me, or is my integrated wired wrong?

Hi Everyone,

So for a variety of bad reasons I took my Luxman 507ux integrated amp apart. Mainly to examine up close the IEC inlet and see about replacing it. Anyway, that issue aside, it seems the amp fuses the wrong side of the AC line?


Here's the inlet as you'd see from the back of the amplifier. I'd expect the left pin to be the line, and therefore it would eventually be the fuse wire right? Please ignore the missing fuse holder except to orient yourself. The PCB the inlet is mounted on seems to be for multiple models and/or countries. The actual fuses are further down.

1681416280395.png

The issue is the wires at the bottom of the inlet, shown below:
1681416393770.png


Underneath the inlet tabs, from left to right the wire labels read BLK and WHT. This appears to be reverse of what I would expect at least in the US. Line should be black, but it's on the right.

OK, so maybe this is just bad color coding?

However if we trace the BLK wire back to the power supply control board the BLK wire IS fused, but the WHT wire is not. In the large PCB in the middle you'll find a black transformer on the right side, the wires from the inlet terminate here:

1681416541805.png


Measuring from the wiring or the pins (as seen above) it is the BLK wire which goes straight to the fuse. You can also see the copper traces underneath.

So am I completely incorrect or does this seem like a manufacturing error in the US?

For Sale Audiotechnology subwoofers (rare items)

To make some room... I will sell some units for projects that I won't build:

Audiotechnology 15E Flexunits Sub/woofer. VERY GOOD CONDITION

T/S parameters from Dayton Audio Test System: DATS V3:
Re 6.008 [Ohms]
Fs 22.61 [Hz]
Zm 37.73 [Ohms]
BL 16.59 [N/A]
Qms 3.361
Qes 0.6365
Qts 0.5351
Vas 219.4 [liters]
L10k 0.5365 [mH]
n0 0.3799 [%]
dBSPL 87.9 [1W/1m]
Ms 205.2 [grams]
Cms 0.242 [mm/N]





Need help to connect speakers to my Sansui R50 reciever

My twist locks at the rear of the amp have been removed so I thought I could connect the speaker cable directly to to power bord or somewhere closer to the power amp section. I don't understand the schematic drawings so naw I'm lost!. There must be something at the power bord to connect speakers A and B speakers or somewhere after eg at the volume knob or speaker selector switch. Please help I love this underrated beauty it just dilivers what you need.

Connecting two amps wirelessly?

Hello. My family owns a cafe, so I'm helping them out with technical stuff. They have both indoor and outdoor seating. We want to play the same music inside and outside, but there are no cable conduits of any kind (brand new governmental building with "hermetically sealed" fasade - windows over many floors). It has revolving doors, so cables through the door is not an option.
We use two normal home hi-fi (Onkyo) receivers with two iPads (one indoor, one outdoor), cabled speakers. Setup is simple to operate. But we need to connect them together without any lag.
I want to split the indoor iPad (to the indoor amp + the wireless transmitter). Then outside amp with a wireless receiver. Alternatively feed the indoor iPad signal into just the wireless transmitter, then attach receivers to both the indoor and outdoor amp. If both amps are on indentical receivers (BT mesh?), they won't have any lag between them.

Any suggestions on what to buy?

Threshold SA/1 with black face meters??

Not your typical amplifier question, more a Threshold trivia question. I have 2 pairs of SA/1 monoblocks, both black face wit the silver meters. A buddy of mine has a similar pair but just picked up a pair with black faces with black meters. They are the original meters as the amplifiers were purchased from the original owner AND they have a Threshold logo at the top. I have never seen Threshold black meters. Anyone know the history behind these? Was it a case of, "A few sitting around and we thought we'd use them" or was there an actual run of these with black meters?

Just curious!
SA-1 black meters.JPEG

Dual Mono Icepower 125asx2 Unbalanced source

Hello all, I am planning on a Dual Mono build of the icepower 125asx modules, my source is rca unbalanced. I was wndering if I could use the ART DTI transformer hum eliminator and converter instead of adding two of those RTX modules from ghent or any of the others on ebay etc. Will this work converting unbalanced to balanced?

https://www.amazon.com/ART-DTI-Tran...-channel+hum+eliminator&qid=1681288879&sr=8-4

Using A Digital Crossover with Passive Sub

Hi all.

I want to try using a passive sub (already own a JBL ASB6112) for my music listening at a computer desk. I've got spare amps and was thinking of using a Biamp TersiraForte DSP as the crossover.

When setting up the crossovers in the DSP, should I set the sub out to 80hz and below and the mains 80hz and above? Or, should there be some overlap?

BTW, does anyone have experience using a DSP for a crossover? This is a very expensive unit, but can get for free. Will it color the sound much?

Thanks!

Rockford T1500-1bd AF oscillation in XOVER card

I've got a T1500-1bd on the bench. Came in with the usual R2035 falling off the board and the LM5110s blown.

I believe the client had this unit mounted on his sub box or something, because all the little heat stakes holding the plastic lid are broken, and when I asked him why he said "the music", though he claims the amp is mounted properly. Inspecting the board doesn't reveal any obvious lead breakages on the heavy components.

Repaired the stuff in the output section, getting HF oscillations at the output transistor gates, but there's an AF oscillation coming from the crossover card (apparently: it's at the output of that card going into the EQ card, and it doesn't seem to be present at the differential input to XOVER, but it's hard to tell with all the common mode noise there thanks to the ingenious placement of the AF preamp next to the rail capacitors...) The frequency is dependent on the setting of the crossover pot, and the amplitude is dependent on the gain pot.

Pulled the HV rectifiers to make the thing safer to handle and less prone to burst into flames, still there.

I had the XOVER card out, and powered it from the bench supply for testing. The oscillation was present but lower amplitude. Was seeing an odd DC bias about the last op-amp in the chain on that board, replaced that, it looked better. Soldered it back in, it still oscillates.

Before I pull that card again (or tell my client to buy a Hifonics), anyone seen this and solved it?
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