Well here's some info on my newest project. (Skhorn is pronounced like the word scorn.)

In short this's something I've been working on for years to replace my Othorn cabs. The design goals going in were pretty much the same. PA or very high level music playback in large or outdoor spaces. The main areas that I wanted to improve over the Othorn are as below.

#1 Cut down on cabinet and panel vibration near the driver.
#2 Improve the fold or reduce build complexity.
#3 Higher overall performance.
#4 More driver options and some less expensive ones.
#5 Increase the “FUN” factor even further

After simulations of what seemed like every cab type and most of the commonly available drivers, I ended up ditching the 8th order BP I had, which looked really good on paper, but was an absolute nightmare to turn from a sim into a buildable cab. Not to mention the extreme sensitivity to mistuning, etc... After that a TH was going to be the follow up and I had it all drawn up but I just wasn't satisfied with it as it seemed like an incremental step rather than something new. Finally I settled on the cab type also used on the M.A.U.L.. It was basically a parallel effort on both designs. The big one just happened to get built and tested first.

The Skhorn is a 24x32x54" cab that is comparable in size to the low tuned dual 18 vented cabs on the market. It's 24cu ft or 680L external volume. Originally I wanted to keep the size the same as the Othorn which is 18cu ft external but using 2 large drivers simply required a bit more volume and a different shape. The Skhorn is exactly 33.33% bigger than the Othorn, so 3 Skhorn are the same volume of space as 4 Othorn cabs.

I settled on a quasi 6th order BP, where the low end is vented and the upper end of the loading is a short, expanding slot/horn, with an opposed pair of 15-21" drivers, in an OD arrangement. I ended up at this while trying to work on translating a standard 6th order sim into wood and screws. I was having trouble getting the upper bass vents to fit into the cabinet and this caused me to look at how a straight slot performed instead since it is MUCH simpler to fit into the cab design. From there it was natural to model the slot with both a positive and negative taper and see what happened. A positive flare seemed to offer some improvements over a simple vent and with tweaking of the length, area and expansion, I found that this type of loading for the drivers could produce a smooth response over a wide bandwidth while also exhibiting some gains over a standard vented system using the same driver.

EDIT: 02/20/18
I have improved the accuracy of HR simulation inputs when compared to the measured ground-plane performance of the final speaker. The HR inputs below are not nearly as accurate as those developed after testing the final cab.

Here’s the cab design.

Greetings everyone I am in need of some NEC 2SB795-L & 2SD986-L These are Darlington Transistors if anyone has any for sale please let me know.

Regards

The Yaoin Tube buffer...:

Arne K

Hello!
I wonder if someone have bought this item or similar?

I just found this on AliExpress:
5 631,87kr | TransAudio D5PRO Clone Dartzeel NHB-108 Hi-End 300W HiFi Stereo 2.0 Channel D5Pro BC capacitor version Power Amplifier
https://a.aliexpress.com/_Eu2kFpq

Hi *,
I bought the LC30 two weeks ago. In my eyes mechanical and optical a very well done device but for me it has two issues:

1. It does not self power on if 5V comes up via USB. Would like to see a jumper inside where this could be configured.
2. The display is uncalibrated. Nearly no movement at low levels and the meter swings much too fast.

I decided to develop an add on prototype PCB which I mounted into the box. There is much space inside so my additional prototype PCB nicely fits in there. It uses two AD8310 devices (used it as I never worked with it before and was curious) to create a real logarithmic output. Also I added some other components to be able to exactly calibrate the meters.

As I‘m not able to solder the tiny AD8310 I bought two of these PCBs, and mounted them on top of my breadboard. I had to modify them a bit to work with audio frequencies but this was quite straight forward.

With two potentiometers I’m now able to calibrate the 0dB and the -40dB levels at 1000Hz. After calibration the levels in between also fit. Only drawback is that the scale of the meters above 0dB is not logarithmic. So the values shown above 0dB are wrong. A damping resistor across the meter establishes critical damping so I get only a very small overshoot from pulses.
I‘m very happy now with this solution 🙂

I also integrated a NE555 and a small DIL Relais that simulates pressing the power button after 5V from USB comes up.

If someone is interested I offer to draw the schematics and publish it here. I also made some fotos during my work that I’m also willing to share. Maybe someone with skills in PCB layouting and producing will kick in and build a circuit board equipped with components so others also can upgrade their unit.

I uploaded the schematics and Fotos of my implementation in the Audiosciencereview thread of the LC30. Please follow the link for more information...
https://audiosciencereview.com/foru...speaker-amp-switcher-meter.57415/post-2270108

Best DrCWO

Hello guys.
Im from Sweden and i saw an older post of someone seraching for the "Audio Generator GAG-808D", and i have one at home if he still is interested, i especially created a account to reach out to him.

So i hope to get help to reach out to him, i tried to reply to his older post but i somehow wasnt allowed to post since i havnt "reach enough credit points" or something?

Hope you guys can help me/him out.

Cheers!

Hello, I am retired and live in Green Valley, Arizona.

Since I'm plugged into the latest GB on the Wolverine amp, I'll be putting in a production pcb from the list below...

PSU Board (2oz blue)


Small heatsinks SK 75 37,5 STS - price on request


MBR40250G - When ordering 100 pcs, the price on the mouser is already acceptable 😉

SSR protect (2oz blue)


Dual Ground Lift (2oz blue)

Bal/Unbal input

Support psu for bal/unbal input
...in proggress

If anyone would like, just write me a private message. The deadline will be 4.5.2025 and the boards will be ordered.

Hi everyone, hope all is well. This is the latest design that I came up with for a Low mu pre-amp with autoformer. Very simple design with a quiet power supply. The pre-amp is intended to drive a 10K impedance. Input will be a 2Vrms digital streamer. I can't find much user experience on the BH rectifier, other than the spec sheet (attached). Would like your thoughts on this design.

klh asw10-125c
Ports are annoying create too much noise . This annoying and unwanted noise is a pain.
Plus my line level inputs are broken .😞 I'll get a pic layer of them.
Amp and driver work fine. Except auto off which never worked .

Hi guys.
Today I'm messing around with a Yamaha B100-115ii bass amp from the '80s. Actually it's only the power amp, the preamp does not exist anymore.
The heatsink on this amp gets very hot, 84 - 88 degree Celsius, you can fry eggs on it...
My question is: is this normal?

Yeah I financed this with my bank
I was blown away after the first spray

Tim Stinson here. Owner of Luminous Audio. Just hoping to share ideas and perhaps obtain some knowledge from others on designs repairs.

As known, Oppo have already issued on market the new series UHD models, starting with a lite and cheaper edition - Oppo UDP 203. It will follow quite soon the next full edition model 205 (expected with the new DAC chip ESS9038 inside).
I may come soon with my considerations about this new model, based on the available pictures. I also hope to have quite soon the opportunity to improve this new model.

I think to open this new thread dedicated to these new Oppo products. Please feel free to come here with your opinions, appreciations, mods and/or improvements in this field.

Just uploaded to AudioMack an album of the best mellow tunes from my Collaborations albums.

https://audiomack.com/hkurtrichter/album/mellow-collaborations

Hopefully this is in the right area.

I have a Cocktail Audio X30 that doesn’t want to power up fully.

When the power button on the front is pressed, the LED briefly flickers green and the relay can be heard to click, but then it instantly powers down.

I had hoped that it was just a fault with the relay, it’s a Handouk HE-1A-DC, but when I have removed it and tested it it seems to operate as intended.

Does anyone have any experience with these?

Any help and all suggestions appreciated.

Hi,

continuing from this thread I would like to open a new thread about interfacing a TDA1541 based DAC to a PMD100 based frontend, but the information about this topic seems to be lost. Here are the links I found:

• Nakamichi glue logic
• philpoole's information
• guido's solution
• some useful diagrams about how to interface the TDA1541A

I also found some information on hifidiy:

• SM5813 to TDA1541
• SM5813 to TDA1541 follow up
• PMD100 to TDA1541A
• PMD100 to TDA1541A follow up 1
• PMD100 to TDA1541A follow up 2

I simulated the mentioned circuits:

• Nakamichi glue logic
• SM5813 glue logic
• PMD100 glue logic

Attached screen shots of the simulations where the timing of the created LE signal is shown.

EDIT: simulation of PMD100 glue logic for stand alone mode. Post #102 gives a summary of the reclocked glue logic circuit I installed into my Arcam Delta Black Box v.1, post #228 contains the final simulation, #229 the latest mcu code to configure the PMD100 in programmed mode and the latest schematics, #230 shows the final state of my Arcam.

The Keystone Sub™ cabinet works well with a variety of speakers of quite different parameters and sizes.
The Keystone is named for it’s exit shape, similar to a keystone. Like keystone lens correction for off axis projection, the keystone exit corrects some frequency response problems that result when a rectangular exit is used with the particular fold pattern employed in it’s construction.

Any person wishing to duplicate my Welter Systems designs for their own use is welcome to, any person or corporate entity that would like to produce them for sale please contact me to arrange a licensing deal to avoid violation of intellectual property rights as defined in section 27 of the Universal Declaration of Human Rights adopted as international law in 1976.

Similar in size to many 2x18” cabinets, exterior dimensions are 45 inches tall, 26.5 wide, 22.5 deep.
Weight is around 150 pounds, 68 Kilos, depending on the drivers and plywood used.
More information about the design are available in these posts:

Tapped Horn Vs. Bass Reflex Case Study - diyAudio

Horn Extender/Wave-guide for TH

Tapped Horn Directivity

Corrected plans are available in post # 487, including parts layout, thanks to NEO Dan, with the exception that the bottom of part "F" is 89 degrees, the front of "G" is a 5 degree angle, the back of "G" is 3 degrees as shown in post #478.
The previous plans #94 and #97 (thanks Oliver) have some errors due to my providing Oliver with some incorrect numbers, sorry for the confusion.
Assembly instructions are in post #1525:
https://www.diyaudio.com/community/...ng-18-15-12-inch-speakers.185588/post-7043072
Photos of finished Keystone Subs and the bass reflex (BR) cabinet as it was used for testing are in post 1039.
Photos of the cabinet interior are in Post #99 and clarification of the 9 braces used in #206 and #451.
Distortion results are in post #12, there is a typo: The * should read: third (odd order) harmonic louder than second.
Those tests were done using 77 volt sine waves (kids, don't try this at home!!), a bit less than "full power", used the 1500W AES power specification of another B&C driver rather than the 1700 W rating of the 18SW115-4.
The upper reduction in output noted in the TH sine wave tests compared to the BR tests are due to the TH upper pass band low impedance points, while the BR has a steadily rising impedance. As the tests were started from low frequency, which has better heat pumping, and ended with upper frequencies, which don't pump as much heat from the voice coil, the upper pass band compression noted in the TH compared to the BR was due to the lower upper impedance causing voice coil heating, raising impedance, causing "power compression" at 77 volts, after less than 50% duty cycle over a few minutes time.

Hornresp inputs are available in post #96 and 130.
The link explaining how distortion was measured expired, an explanation is in post #315, and a correction in #316.
PASC built a Keystone Sub TH ("tapped horn") and a xoc1 18" TH and reported his findings in posts #114 & 115.
The lower frequency response corners using a partially covered exit, ("step down" mode) is in #262, but the description is wrong:"TH18S20" has the upper 5 inches of the exit covered with plywood, exit is 20" from bottom to top. The "step down" cover results in as much as an 8 dB increase in 30 Hz level (with only 8" from bottom to top left open), but with progressive losses in the upper bass range, so for most music the trade off is not worth the extension.

The Keystone B-Low (a low "B" note is 30.87 Hz) testing started early October of 2017, initial reports using a B&C18TBW100-4 driver are in post #1135. Photos and the response curves with the B&C18TBW100-4 and the 15” Dayton PA385S-8 and a "step down" cover plate are in post #1167.

Comparative tests using the Keystone Sub loaded with an 18 inch B&C18SW115 (four ohm nominal), a 15 inch Eminence 4015LF (eight ohm), and two Eminence Lab 12 (6/2 =3 ohm) were conducted in March of 2011.

The same 16.6 inch diameter cut out was used in each case, the 4015LF used a “doughnut” adapter, the Lab 12s used an adapter that centered the two speakers on the cut out and provided a stand off so they would not slap at high excursions. The Lab 12s have a "saddle shape" frequency contour, the 96 Hz peak needs to be removed with EQ for flat response.

There are a few other peaks and dips in the response curves due to very windy conditions, often requiring waiting minutes between gusts to record responses. Test day was literally a sand storm, the bottom of the cabinet was filled with coal dust and tumbleweeds after.

All the speakers were driven with the same level. The 4015LF is actually about the same sensitivity as the 2x12 pair, since it has about double the impedance minima.

A BR (bass reflex) LAB 2x12" (36 FB) cabinet, exactly half the size of the Keystone sub is shown in the blue trace, it’s upper response is slightly reduced due to a Butterworth 125 Hz filter, all the other subs used a BW 1000 Hz filter.

As can be seen the 15.5 gross cubic foot Keystone Sub TH loaded with the B&C18SW115-4 sensitivity averages 6 dB greater than a 8.75 gross cubic foot BR.
Twice the power and drivers in a pair of BR cabinets weighing at least 40 pounds more, and occupying 2 cubic feet more trailer space are required to equal the SPL output of one Keystone Sub. The pair of BR would be capable of few dB more output below 45 Hz, the Keystone Sub +3dB or more SPL above 45Hz, more "punch" where you may want it.

There are subjective sonic differences between the TH Keystone Sub and the BR cabinet when they are driven hard enough to approach the thermal and linear excursion limits of the driver. Running subs at "full tilt boogie" is common for most applications desiring the maximum output for the minimum trailer space, and the most "bang for the buck".
1) The TH cone is under more stress at the same input voltage than the BR, this results in slightly more distortion, and the distortion spectra is at different harmonic points- the TH sounds "louder" when driven hard.
2) The BR looses LF output due to "port compression" (turbulence) relative to upper level. The TH does not suffer from any "port compression", but suffers from more upper pass-band "power compression" than the BR. The net result is the TH sounds a bit more "aggressive" (more 45-100 Hz output) at low drive levels compared to the BR, but at high drive levels, sounds "fatter" due to the LF range not reducing, while the upper range is "compressed".
These two differences are program dependent, music with wide dynamic range won't reveal the thermal problems, while compressed and droning LF content will increase both, subjectively and measurably.

Subjectively, with the same drive level, the Keystone Sub using the B&C18 seems a bit more “punchy”, more stuff falling off shelves in the shop, and more "foot feel" in the sidewalk vibrating during out door tests. The B&C18 takes full power from a bridged Crest CC2800 effortlessly, while the Eminence 4015L 15" seemed a bit “wheezy” at a lower drive level, the Eminence LAB 2x12" in between.

The Eminence speakers used in the tests are a bit more sensitive, the 4015LF would be the best “bang for the buck” output per watt/cost for low power applications. Making a slightly wider cabinet would allow two 15 inch speakers to fit, which would probably allow about 3 or 4 dB more output at the low corner, and 5 or 6 dB more upper level with only about 20% increase in cabinet size. The Lab 12s sound cleaner, and with the same voltage applied are louder than the 4015L. For those with limited amplifier or AC power or budget, the Eminence speakers are good choices for the Keystone cabinet.

Looking at the low excursion of the Keystone vs. BR in the region from 50-90 Hz, it is evident that the cone is under a lot of stress, quite audible sounds of distress may be heard at high drive levels using lightweight (low Mms) cones.

The very stiff cones of the Lab 12 and the B&C18SW125 can take the stresses and sound clean, when pushed hard the 4015LF sounds pretty awful.

The B&C18SW115-4, though less sensitive than the Eminence speakers, will go a lot louder with a cleaner sound given more power due to its greater linear excursion capabilities, more even BL curves (the magnet "pushes" harder further), more power handling with better cooling, and a super stiff cone and suspension.

Using Hornresp simulations at rated Xmax values, (and impedance minima) average level from 35-100 Hz, the Keystone has these output levels:
BC21SW152-4 131.6 dB, 92 volts, 3.4 ohms, 2489 watts
BC18SW115-4 130.1 dB, 76v, 3.43 ohms, 1683 watts
BC18TBW100-4 127.8 dB, 59v, 3.32 ohms, 1048 watts
Eminence 2xLab12 126.3 dB, 36.5v, 2.22 ohms, 600 watts (300W per driver) 128.4 dB at 40 Hz.
Eminence 4015LF 121.9 dB, 38v, 5.17 ohms, 279 watts

The average impedance is higher than the minima, closer to the nominal rating of the speakers.
Other than the 4015LF, which did not sound good (by comparison) in this cabinet, the other drivers are capable of considerably more peak level (140+dB) without sounding bad.

I consider "safe" limiting for the Keystone sub using a B&C18SW115-4 to be as follows:

A) Use the DCR of the loudspeaker to determine the voltage setting, the DCR of the B&C18SW115-4 is 3.3 ohms, the minimum impedance of it loaded in the Keystone Sub approaches that value at Fb, where cone movement (and forced air cooling) is also at minimum.
B) The manufacturer's "Continuous Program" rating of 3400 watts is OK for peak limiting, using short time constants of a few wavelengths duration.
C) Long term "RMS" limiting with a time constant of longer than 500 ms (milliseconds) should be no more than half the rating of 1700 watts (850 watts), as AES ratings are conducted in free air (the actual power dissipated is less than 1/2 the nominal "wattage"), while driver's voice coils heat up far more when loaded in the Keystone "tapped horn" due to the far lower average impedance than the free air test. If you tend to get "heavy handed" on the volume fader playing compressed music over long time periods, use 425 watts.

If using other drivers, substitute their "Continuous Program" and 1/4 to 1/2 of the "Nominal" RMS rating for peak and average limiting settings, using the DC resistance, not the nominal speaker impedance for figuring the compressor/limiter threshold voltage settings.

Compressor/limiters will not protect a loudspeaker from excursion related mechanical damage.
Your Keystone sub should use a 30Hz 24 dB per octave Butterworth high pass filter to protect drivers from mechanical damage if amplification capable of exceeding the driver's Xmech rating are used.

Art
Welter Systems, Inc.

Hello all - I hope your projects are going well.

Today I got a CA Azur 840a for a very reasonable price. The seller claimed input one was dead on both the RCA's and XLR's. Reading up on this amp - I discovered the inputs are controlled by relays - and my suspicion was that the input one relay had gotten sticky. Not so - I can hear it activate robustly. Turns out the wee toggle switch on the rear panel that selects either the RCA or XLR inputs has been broken and is flopping about.

I found the service manual and I cannot, for the life of me, find mention of this switch anywhere in it.

In my initial listening - I like the sound of this amp - and I'd like to get it working completely. All the other inputs operate fine.

I'm happy to either replace the switch - but would love to discover the part # so I can order it before taking the amp apart - or simply rewire the circuit so that input one is hardwired to the XLR inputs. I don't often sell gear and this will likely stay in my collection for a good while. So getting it back to factory spec isn't important to me.

But I can't discover in the schematics or the BOM what's needed for either approach.

Any tips?

Link to the service manual is here: https://elektrotanya.com/cambridge-audio_azur-840a_ver.2_sm.pdf/download.html

Thanks in advance!
RK

It's nice to present this project - separate delta sigma modulator for a dsc2 dac.
Special thanks to Jussi and Pavel.

The basic idea is to convert pcm to a dsd stream without the use of a PC.

Design flow goes as follows:

i2s serial data is converted to parallel, next we have the first interpolation fir filter,
in this filter the data is oversampled x2, x4 or x8 - this depends on the incoming data rate.
(for 44.1kHz we have x8 interpolation, for 96kHz x4 and for 192kHz x2)

next, the data is going to the two stage CIC filter and is oversampled x32 to final x256

Then the data is going into the sigma delta 7 order modulator, which has classical CRFB structure,
as I said earlier all arithmetics are done in CSD arith, so no multipliers here.
all coefficients are carefully optimized using delsig package
If someone asks, yes, there are g0, g1, g2 coeffs.

At the end the dsd streams are time aligned using ODDR2 primitives

XC6SLX9 is almost full, so there is no ability to add anything 🙂

The device was designed to run with a mclk of 22/24 MHz.

To upload the attached bitstream file to the board you need a Xilinx programmer cable and Xilinx program Impact.

In the next post my friend PJotr will post gerber files, BOM and some measurements.

I hope this project will be interesting for someone.

DIY use only!

--------------------------------------------------------------------------------------------------------------------------------------------------------
Update 24.07.2023 New firmware !

First of all, I'd like to thank Markw4 for your help!

The entire software is practically completely new.

The first FIR filter now has x8 fixed interpolation (fs 44.1kHz - 192kHz), has 2048 taps, 32 bit coefficients and 100dB stopband attenuation.
Then it's a two-stage CIC filter and it's oversampled to the final x256. Oversampling depends on the rate of incoming data.
Then we have a 5-order sigma delta modulator, which has classical CRFB structure, with noise shaping and dithering.
And as before, at the end the dsd streams are time aligned using ODDR2 primitives.

We made tens of different firmware configurations and finally chose this version after listening sessions.

Latest firmware:
https://www.diyaudio.com/community/threads/simple-dsd-modulator-for-dsc2.370177/page-42#post-7407495

I'm rebuilding a Classe CA-401 after one channel blew out. I'm documenting the entire experience to keep track of everything I've done and to help out others. Enjoy!

Every power transistor in the channel was blown. Here's a picture of the vaporization leftovers of the 10N20 and 10P20 gate resistors. Also, check out the 383R VBE multiplier resistor residue in the top right corner:

Does the IPS LCD LED display panel suffer wear and tear and loss of power performance of the LEDs, backlight and liquid crystal when stored for many years without use and without power?
Will the LCD develop dead pixels and become slow after storage long?

Hey, my name is Mike Flathers, I'm from Lake Stevens, WA (Seattle area). I do a lot of DIY, professionally I am a creative pastor and spend a lot of time in AV, building and maintaining PA systems. I love keeping old quality gear alive!

evotronix KARPEN

Good evening everyone,
my name is Fabio and I'm writing from South of Italy - signed up aware of my ignorance in DYI as well as that there is always time to learn if you have a pinch of good will!

This request is for a friend of mine and it's for the DAC module of Twisted Pear 9028 DAC, preferably from someone in EU.
There was one sold here not long ago but we missed that and hoping that someone else also has it in his closet.

Howdy... I'm a regular on SBAF, but a newbie here. I've built some bottlehead kits in the past, have also played around with some speaker kits. I want to delve a little bit deeper into speakers and figure this is a great place to get more info.

Single Ended Tokin SIT THF-51S Common Drain Mu Follower Amplifier , 45W?

Edit: 70W Version added:https://www.diyaudio.com/community/...mu-follower-amplifier-45w.371187/post-7855849

Edit: Stereo Version to suit 4U 400mm Chassis, 44VDC Power Supply, added: https://www.diyaudio.com/community/...mu-follower-amplifier-45w.371187/post-7928760

I used to be a huge fan of single ended common source SIT amplifiers. I had a 2SJ28 version of Michael Rothacher's Hammond 193V choked loaded L'Amp and I also have a THF-51S version of Mr. Pass's BAF2015 2SK77 amplifier (Zen Mod's version is the Singing Bush). I took the 193V out of the L'Amp and tried it in a higher Watt 2SK180 L'Amp. Unfortunately that did not work out as well as I had hoped in that it had thermal runaway issues. However that turned from bad to good when I tried the 2SK180 in common drain mode with the 193V as load, and I was pleasantly surprised:

https://www.diyaudio.com/forums/pas...93v-choke-loaded-2sk180-lamp-post6601437.html

So now I am a huge fan of SITs in follower mode. I suppose I shouldn't be surprised as Mr. Pass's recent DIY Sony VFET Part 1 is also a follower amplifier, and Mr. Pass has impeccable taste. So I got to thinking that my THF-51S BAF2015 monoblocks are good candidates for conversion to common drain follower (inverted BAF2015 THF-51S?).

For the CCS/mu follower I needed to find a suitable P-Channel enhancement mode Mosfet. Unfortunately they are not in great supply, especially when I was thinking power dissipation of about 100W. So with a safety factor/derating factor of say four, I was looking for a device rated at a minimum of 400W. After some searching the internet I found the IXTQ26P20P. However it was only rated at 300W. I was willing to give that a try though. Its datasheet had a Safe Operating Area chart showing DC parameters at Tc=70C, Tj=150C and it looked very feasible. Then I found an even better device that was used by diyAudio member Lynn Quam in his SIT3X amplifier design: the IXTN40P50P. It is rated at 890W, so plenty of headroom, and it is also the same form factor as the IXFN140N20P in the BAF2015 amp. Also Lynn had the Spice model posted so I didn't need to search for it. Thank you, Lynn.

Since my plan is to repurpose my BAF2015 THF-51S build, I will be using the existing chassis and power supply. The power supply was designed to comfortably output 60VDC at 3.0A. It is currently running at about 2.3A and 62.5VDC. The chassis has a fan cooled heatsink and temperature is not an issue.

So I started out with some LTSpice simulations and decided to go with the mu follower and not just straight CCS, as the mu follower's additional power output was enticing. I found 62VDC and 3.0A was a good operating point. Simulations showed 45W into 8 Ohms was feasible. In reality, to be determined.

EDIT:
New - PCB Available: Start of PCB Design at post #173

I am a relatively new tube amp DIYer. Built two spud amps, a 6BM8, and a 6LU8.

Now, I'd like to try a single ended EL84. I understand that there are at least three output modes, pentode, triode strapped, and ultralinear. I haveno interest in triode mode.

My understanding is that pentode mode would have highest power, and highest distortion. That is mitigated through global negative feedback which reduces distortion, but also decreases output. Ultralinear, reduces distortion,likely better than gnf, but doesn't it also reduce output power?

My goal is to drive the el84s to getthe highest listenable output, basically, headroom. I normallylistento my 6lu8 at a modest volume, and likely similar volume for the el84s. My quest would be not to have the lowest distortion at max output, but low(ish) distortion at listening level, butwiththe mostheadroom I can get.

Now, I know gnf is typically defined in dB negative feedback, but I do not have the knowledge to understand the relative significance of say 15db at a 3 watt output. Especially compared to say any power sacrifice going UL.

There are ma y schematics outthere using both either UL. or gnf.

Help me understand the benefits of each approach.

Tia,
Roger

Hi all,
my NAD c326bee has serious problem. It keeps turning on and the buttons on front of the panel are irresponsive and also the standby button. The only mode to turn the amp off is to use the hardware switch on the back panel. When the amp is in this state (power on but irresponsive), it becomes quite hot. The problem was fixed in april with a quite expensive repair, now the problem returns.
Is there a way to fix this weird malfunction?

Thanks

I have for sale a new, assembled and tested module with MJ’s cap mx and active bridge rectifier.
Pcb is done by Analog Design.

Sold

Hello all,

My name is Neeraj, I am from Maharashtra, India. I am 38, but new to the world of DIY Audio and am not from a technical background (I was a commerce student) but I am very much interested in audio.
Some years back, when I came to know that the expensive audio equipments can be made at home, I started studying from the very very basics of electronics and started learning etiching pcb at home.

Till now I have eatched PCBs and assembled Amp Boards like couple of designs for TDA7294, Couple for designes for TDA2009, TDA2030. Some transistor amps based on the design of Sir Marshell Leach, Honey badger Amp, Apex A14 Amp. Also OM2.7, OM3 and ISOTOP from Russian website. Some preamps like P20, P30, P4 etc, some Subwoofer filters including sub filter from Mr. Mile, also eatched some soft start, Protection pcbs, power supply pcb, selector pcb etc etc... All are working.
Using some of the above PCBs, I assembled some Stereo Amps and some 2.1 amps using DIY pcbs and Old Dead AVReceiver cabinets (bought from scrap) . All are working without any major issue and with regular improvements.

There were some failed projects too. some noisey preamps were there, some amp designs were there like Jat501, Apex SR150, Apex SR100 etc etc etc.
I have Zero knowledge of PCB designing as of now, hence I need to rely on PCBs designed by the experts. But I will start learning it soon. My failure to success ratio is 1:1 as of now will try to improve it.

After 4 to 5 years, One thing I understood very well that "DIY IS NOT CHEAP". You will always end up spending more on DIY then on a professionally made commercially available similar powered AMP purchased. Also there are some issues like getting good quality (Original) componants at an appropriate price. I have seen vendors selling componants at 3 times 4 times the actual price. And the most important part is DIY have its limitations, It is not imposible to DIY Good Quality DAC, Preamp, Digital selector etc etc but the cost to do that all will be hudge. But, for me, I am not in a stage where I can turn back, hence I will continue doing it and will try focusing on Class AB Power Amps Only.

Since I have read about Apex A40 Amp a lot and every body was loving the quality of sound it produces, I also tried to assemble it. But kid of failed as for now and trying to find a solution on the forom.

Hello, my name is João, and I’ve been working with a few friends to develop an audio analyser called beHydra (feel free to check it out here: https://beembedded.com/behydra/).

I joined diyAudio to learn and understand everyone’s needs when developing audio related products, which is why I’m developing the audio analyser myself, given what’s in the market is a bit expensive and not necessarily developer friendly. Happy to discuss what I've been working on 🙂

Looking forward to exchanging ideas and learning from everyone here!

Hi there,

Up for sale is a large lot of power tubes, all in the octal family of EL34 / KT88 / 6550 / KT90 / 5881 / 6L6 and 7591.
All details can be found in the file attached to this post. All good and tested in my calibrated TV7-D/U. You can find the actual reading and the "good" threshold for comparison, plus a lot more information on condition, origin, etc. And if there's anything else you are missing, just ask.

Price for the entire lot (54 tubes): 650 EUR / 700 USD. Shipping (priority and registered) should be between 25 EUR (Europe) to 50 EUR (America / Asia).
Payment by bank transfer or Paypal F&F.

I am also open to reasonable offers, either for the whole lot, or for significant parts of it. Offers for smaller lots are also welcome, but please understand that I need to prioritize the bigger ones. I will try to reply swiftly to any offer or question.

After one month from this post, I will start offering whatever is left in individual lots, but prices will have to reflect the unavoidable overhead of smaller transactions.

Thank you!
Ignacio

Hi All,

Sharing this side project of mine which has been my daily workhorse streamer for the past few years.

Please welcome Randy to this busy and wonderful neighbourhood of RPI/SBCs music streamers 🙂



Randy is built with minimalism and user experience in mind.
It's probably the first RPI streamer that's not using MPD and instead using a powerful media streamer called MPV with lot's of tweaks to get good quality sound.

I am releasing it as an early version to get more feedback and see if there is interest to push it forward and therefore at this stage some things are kept minimal.

What you get right now:

• Beautiful and responsive streamer player
• Awesome sound quality with no filters or manipulation
• Plug any USB drives to add your music collection
• Play web radios and lots of streaming sites like soundcloud, mixcloud
• Always playing playlist
• Save things to favourites or just easily search for them
• Should work on all RPI models and ubuntu/debian based systems

What makes it still an initial release:

• The installation is right now done on top of Ubuntu or Raspberry PI OS Lite with some commands
• It's currently set for USB DACs, but you can follow instructions to set up an i2s DAC instead
• NAS instructions here and in this thread
• I've left out things like Spotify connect, Tidal, UPNP etc..

Randy has been successfully installed on:

• SBCs such as RPI, Orange pi Zero
• Thin clients such as Intel NUC, HP T-520 Thin client and Dell 3040 mini

Links and instructions:
Website: https://randy.typedream.app/
Github project page: https://github.com/PapaSimons/Randy
Wiki: https://github.com/PapaSimons/Randy/wiki

Why should you try it?
For the same reason we DiyAudio folks try different capacitors and opamps..

How can you help?
Try it out and post about how you find it, hows the sound, any improvements, ideas etc..
I also have limited hardware and time to test things out, my RPI3b just died a couple of weeks ago so it's right now playing nicely on my sons' RPI zero 2w.
If you do have new hardware like RPI models, DACs and it works then drop a note. If it doesn't work drop a note and we can try to figure out how to get it to work.

Enjoy!

Amazingly, 40 years on, one can still find plenty of DIY examples on the internet.
It has been on the to-do list for long.
And finally we got round to it ourselves, with 4 different version.
https://www.diyaudio.com/community/threads/hiraga-le-monstre.5462/post-7622181





Patrick

.

HI everyone.
I have spent some time designing my system and have now almost completed the preamp design. I am at the moment looking into a headphone output, and hence looking at various circuits around the bazaars. I came across a simple circuity using THAT 1646 balanced driver amps that looked promising but I am confused as to why the input is connected to the amp sense terminals rather than pin 4 of the amp. Hoping someone can explain why this has been done. I have attached the circuit here for reference

Emi Filter Plus Elite & DC blocker schematics and motherboard

I had built my own version of a very advanced EMI filter which is still available from here https://775mv.com/product/power-emi-filter-for-audio-12a/ for being purchased at a good price, but I like building things, and modify them according to my needs. First I did not need to filter my entire house using a single high amps filter, because it may be more efficient to use several low current filters instead of one. Therefore I could choose higher inductances with higher attenuation of the noises which circulate on the 220Vac power supplies. I am using a DIY audio Dolby Atmos 16 channel amplifier power, having 8 distinct stereo modules, each with its own power supply, torroidal transformers and rectifiers.

Situation before adding EMI filters:
a) trafo noises and hum because of the DC offset which exists on the network, and obviously I didn't used any DC blocker circuit before.
b) regular EMI filters are just not good enough and they don't filter below 100 kHz, and I needed something to filter below 10 kHz
c) all power transistors from each module where just unusual overheating, without pushing too much the volume ... because all these noises were just passing through into the DC components, almost unfiltered by the electrolitic capacitors.
d) audio distorsions were very intense after pushing some power into the loudspeakers and transistors continued overheating very much
e) ground noises even after changing all audio cables with high expensive professional ones.
f) big noise in the loudspeakers after switching to power on, a big sharp and short boom.

Situation after adding individual EMI filters to each module:
a) no more trafo noises and hum, DC blockers have been added too.
b) filtering all noises and foreign signals above 10 kHz, present in the 220Vac wires from the surge protection unit of my home.
c) transistors are no longer overheating, sound quality improved because of using them in normal range, and the entire sound quality improved.
d) very soft noise in the loudspeakers after switching to power on, low intensity short boom.

The schematics contains: a) DC blocker, b) Advanced ground loop breaking, c) Deep suppression of differential noise stage I (F1,F2,C1,C2,C3,C4,C10), d) Zero noise overvoltage protect (RV1,RV2,RV3) and also Gas Discharge Tube technology GDT, e) Deep suppression of common mode stage using Tr1 and Tr 2, followed by suppression of differential noise stage II and III, (L1,L2,L3) and f) Careful dempening of complex filtering (C8 and C9)

I'm not the seller, as these are somewhat rare to find I will share the ad found here : https://www.finn.no/recommerce/forsale/item/396684651

After 2 days of scouring Mouser, Digikey, image files, and various manufacturers, I can't find replacements for this 2mm pitch, 11 position, square pin receptacle/connector that include the PCB stabilizing clips at the ends. I've tried multiple keyword variations, and all I can find are right angle receptacles without the clips. I'm redesigning some burned circuit boards for a rare Audire amplifier, and would definitely prefer to replace this with the same configuration if it's even possible.

Any help much appreciated - thanks!

Buddy Holly is great music.

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My name is Prezmo and I live in Poland.
In my free time, I do audio electronics as a hobby.
I came across this forum looking for information on improving the JLH1969 headphone amplifier.
I got my hands on a ready-made Gzlozone board, but the sound doesn't satisfy me. I'm looking for solutions to improve it.

Hi. Thanks for reading. After listening to a pair of dipole speakers I am impressed by the spaciousness of the sound. Two drive units connected out of phase with each other, which destroys the direct sound reaching the listener’s ear, so the listener only hears the reflected sound from the room’s walls, causing a spacious kind of sound.

But it seems to be an expensive build, with more drive units required. Is it possible to mimic dipole speakers with a non-dipole speaker, by using the out of phase back radiation in some way. I tried it by removing the back of the speaker enclosure, hoping the read radiation would destroy the direct sound, but it did not work well, the dipole speakers sounded much more spacious

I've been using Fabfilter Pro-MB for some time now to reverse some of the effects of music track dynamic compression during mastering...but not mixing, of course. I've found some interesting tidbits of information while using it:

1) Dynamic expansion with a good multiband upwards expander (like Pro-MB) is possible if the dynamics of the music track haven't been completely crushed into oblivion. In DR Database terms, this means that if the music track has at least a 6-8 dB rating using the "TT Dynamic Range Meter" (the standalone version or as a plugin for foobar2000), you have a reasonable chance of a good listenable outcome using multiband expansion. The maximum DR ratings that can benefit from expansion seem to be around 13-14 (dB-crest factor) on the DR Database scale. Any tracks compressed to lower dynamic range values seem to be "lost causes". It's much more productive to go on a hunt for a higher dynamic range version of the recording rather than trying to use a multiband expander.

2) The plugin settings used to expand tracks are usually most successful in increasing dynamic range in the higher frequencies of a track than the lower frequencies below ~100-200 Hz. This means that the crest factor ratings of the tracks from the TT DR Meter may not change very much (due to the fact that crest factor is really measuring bass dynamic range, but not really higher frequency DR), but the tracks themselves will present a much more crisp and forward sound quality for dynamic transients--like ride cymbals, crash cymbals, bells/cowbells, glockenspiel, all handheld percussion instruments (particularly latin instruments), string attack transients, marimba/vibe strikes, drums, and human voice transients.

3) The "steeliness" of string orchestras used in lush pop string arrangements and mass string orchestral scores (classical) will largely be suppressed if using the multiband expander carefully. This was a big surprise.

4) Any human voices, particularly female voices, will begin to sound much more realistic and without typical harshness that comes with listening to recordings having compression applied during mastering. This was the biggest surprise of all in my explorations using the expander.

5) The albums that respond most strongly and easily to multiband expansion seem to include those that had analog compressors applied during mastering (e.g., early-late 1970s albums), which apparently used continuously varying nonlinear compression curves without a sharp knee breakpoint/thresholding applied during mastering.

6) The music genres that seem to respond most strongly are funk, rock, folk, jazz (including smooth jazz), progressive rock with lots of drums/percussion, dance, and related genres. Those genres that seem to respond with more difficulty include smoother music genres having lots of midrange energy (i.e., ambient, new age, classical string orchestras, classical guitar, etc.).

7) All tracks that have used multiband expansion need to be adjusted before and after expansion using parametric EQ demastering.

__________________________________________________________________________________________________________________________

It's clear to me that the use of a multiband dynamic range expander is now standard equipment for my typical demastering tasks that I perform on most of my incoming discs.

I don't recommend trying to do expansion "on the fly" (without review and adjustment of expander settings track by track) unless extremely mild expander settings are used, which leads to barely audible subjective differences in the compressed tracks. Using an expander offline and taking a little time to get the setting right to get the best and most audible results is my strong suggestion in using these type of plugins. However, the task only has to be done once for the music tracks--then saved for future listening, instead of having to set up a custom string of plugins and parametric EQ settings each time a music track is played.

(My original text above was originally posted to another audio forum, albeit an unstable one, and has been moved to this forum to ensure its longevity.)


Chris

I'm looking for a PC hardware expert who can help me diagnosing and repairing a PC motherboard.
Mombo is an Asus P6T deluxe ver.2 socket 1366.
Mombo fail in POST procedure.
Nothing ,dark screen.
I have check with another good power supply,another graphic card, pulled memory,nothing.
Power supply start,CPU cooler fan start,nothing else,no beep nothing!
Any help out there?
I have done some measurements around VRM and I didn't see any voltage across electrolytic caps.

Just got this on cd. Reminds of the Stone's Exile on Mainstreet. Good hard rocking vibe throughout. Not too much tired top 40 stuff either.

I've got a Jensen 15" woofer and three Jensen tweeters someone had pulled from an Emerson console and sold online. The woofer itself has Emerson on it which likely means it was designed specifically for Emerson by Jensen or maybe just that Emerson asked for their name to be put on it.

I used the cabinet from a cheap 1950 Silvertone console that wasn't worth restoring (except the V-M Tri-O-Matic record changer which will go in my Magnavox CR-198C console) as the cabinet for the speaker. The only good thing about the cabinet is the piece of plywood I used for the speaker baffle.

The stock driver configuration of the Emerson console had the woofer in one spot and the three tweeters arranged in a triangle shape at an angle from the woofer. I arranged them as seen here. The extra hole was when I had a pair of dome tweeters on either side of the top tweeter. Didn't like how it sounded as it wasn't very good up close to the speaker given the distance between the two domes.

So I found a ribbon tweeter I had and used that which improved the sound.






I made a 6dB/octave crossover for the speaker as that's what was originally used except the woofer didn't have any inductor in series with it. The reason for the added tweeter crossed over so high is I didn't like how the cone tweeters didn't reproduce the treble up to 16kHz that good.




The plan is to eventually have a new proper open back cabinet built and make it to where the ribbon tweeter mounts above the top cone tweeter.

Cannot decide if I want to paint it black like the baffle is or have it properly finished like the rest of the cabinet is.

Should I keep the 6dB/octave crossover or switch to a 12 dB/octave crossover as in will it make the speaker sound better or is it best to keep the stock crossover slope?

EDIT:

Here's a 12dB/octave crossover I've calculated. The .16mH, .32mH and .12mH inductors I could only get .15mH, .13mH and .33mH, however if I go with this crossover I will measure those and see how close they are to the calculated values, although if the inductors have a 5% or higher tolerance (website doesn't specify) they will be within the calculated value.

Good morning everyone,
my name is Alex and I come from Italy, and since we are on the subject of audio, I specify that I live in Sanremo the city known for the Italian song festival.
I have a PC with a b650 motherboard and a ryzen 7600 cpu, a xonar dx audio card and hivi t200c speakers.

I signed up to learn how certain mechanics work and improve my audio chain in the future.

Greetings from the Ligurian Riviera!

Hi all,

I'm trying to repair my Sony CMT-M373NT bookshelf stereo which has rendered excellent service as a USB sound device with my PC for nearly 20 years. 25W + 25W output, with 6R speakers

Symptoms:

• System starts as normal, relay clicks, sound is produced, but:
• Right channel has a buzzing/hissing sound and none of the actual signal. Constant volume, regardless of volume setting.
• Left channel is 100% normal
• Result is the same when switching speakers around
• Same can be heard through headphones
• With right speaker disconnected, the system can be used Left channel only with no issues
• With right speaker connected, the system drops to protection mode within a few seconds

Looking at the circuit diagram in the service manual and knowing that these components are well known for going bad, I’m strongly suspecting the STK403-030 amp module. Anyone think I might be barking up the wrong tree?



However I can’t probe it in situ because of the way the system is built; the STK and all of the supporting components are masked by other closely stacked and rigidly interconnected boards. However with the board out and checked on the bench there are no dead shorts on any of the transistors or capacitors and no open resistors.



I was planning to solder fly leads to the pins of the STK in situ and then reassemble the unit to allow me to probe voltage the STK pins with the whole thing powered up. Assuming that’s confirmed bad then a repair would be pretty straightforward if it weren’t for the lack of availability of these STK modules. They are listed on ebay and from China but it seems that more likely than not they will be fake, although they do look quite convincing, with the same moulded top cover.



Are ALL STKs subject to fakery? This system was bought in 2004ish so we’re not talking about parts that haven't been produced in 40+ years as with some models of STK. Does the top cap come off these easily? If so I could probably buy an ebay one, pop the lid and compare the internals with the original one, a fake will be easy to spot I assume?

Then as I’ve started reading I’ve realised that it’s probably fairly simple to directly replace the dead STK with a couple of either LM3886 or TDA7294. Could anyone offer some tips/pointers here?

As a hobbyist electronics tinkerer I’ve designed, built and coded many Arduino-based devices to do with supporting functions in car engine conversions etc so I’m no stranger to the skills required and I have a decent working understanding of the electronic principles at play, but the specifics of audio/amplifier design are beyond me at present.

Cheers!

Hi all,

Newbie here looking to get some advice and learning on repairing some old Sony minidisc units. Currently my Sony CMT-M333NT has died on me (push power error) so looking to get some help on that.

Sav

Just wanted to drop in and say hello! I’m a mechanic by trade, but I’ve always been fascinated by electronics and audio. Lately, I’ve been tinkering with some old speakers and amps, trying to learn more about DIY audio projects. Figured this would be a great place to pick up some knowledge and maybe even contribute where I can.

Hi, I have a nice cabinet of a very closely spaced MTM. Stock drivers are ok but deep bass somewhat lacking for size of cabinet. The woofers aren't really designed for it like a more modern driver. A warm but "woody" kind of sound.

Trying to decide using 2x Mark Audio Pluvia 11s per can either in 1.5 way or 2.5 way with tweeter - or both with crossover switch!

Or, using SB Acoustics 17nac woofers in 2.5 way or mtm and a low Fs tweeter (must be small neo/small flange due to existing arrangement).

How are the Pluvia with bass? Is it worth using them as more of a woofer? They would certainly be the more artistic option as the cabinet is a darkish orangey kind of wood veneer. Roughly 40L.

Drivers need to fit in a 172-3mm rebate if others are to be suggested; slightly smaller can work too

Offered for free is my childhood collection of Audio Xpress and Speaker Builder magazines. There are 90 different copies of Audio Xpress, 10 copies of Speaker Builder, one copy of Glass Audio, one of Audio Electronics, and some random copies of UHF and Inner Ear.

I was lucky enough to have these growing up as a kid / teenager, and would be happy to pass that experience on to someone else. These are by no means in collectible condition, but they are all clean, dry, and ready to be enjoyed.

Also included is a copy of Mullard Tube Circuits for Audio Amplifiers and one copy of Audio Amateur Power Amp Projects.

Free to anyone willing to pick them up in the Ottawa area (downtown).

Cheers,
Owen

Hello,
I created the board using special software based on the published schematics and PCB photos!
Shannon Park (diytube.com) Unfortunately, his website and forum have been taken offline,
but I saved everything I need (e.g., firmware for the Arduino Nano).
I used the top side of the original board as a template, and that was relatively easy.
The back side was more difficult, as there isn't a decent photo of it.
And the back side also serves as the ground plane,
so you have to look at the schematic again for each component!
To protect the tubes and fingers, these things are available at aliexpress



audio Xpress:
Our DIY section also brings a great project from Shannon Parks, with its Arduino-based real tube preamp.
This is a simple 12B4 linestage controlled by a Arduino Nano board and the tube power supply is probably
the simplest in our magazine’s history: it uses a 24V, 1A desktop supply.

I'm only selling the boards. If you're interested, please PM me.

Pre-BAF appetizer project posted. Enjoy 🙂

Build This MoFo!

EDIT: (6L6, Jan ‘23) above link is dead, here is link to the article - https://6moons.com/audioreviews2/mofo/mofo.pdf

Hope to see you at BAF! Don't forget admission is free for everyone who brings a project.

Let us know what you're bringing in in this thread:

What are you bringing to Burning Amp 2017?

IMPORTANT NOTE: A Zener diode from the MOSFET Gate to Source is needed to protect the MOSFET from inductor "kickback" I got away without this when using MOSFETs with high maximum VGS and lower supply voltages, but had not anticipate the range of FETs, inductors, and supply voltage that might be used. Even when the stars align, it's too close to not consider the Zener mandatory.

There's already a place for this diode on the PCB sold here in the store. When my stars align, I'll update the article pdf.

In the meantime, my good mentor PRR has provided some illustrative filler:
https://www.diyaudio.com/forums/pass-labs/313649-build-mofo-279.html#post6368030

Hello,
I have 2 chokes Hammond 193T (50mH 2A) for sale.
Shipping from Germany.

Hello. I come from Vietnam, my real name is Bao Huy, 32 years old. Sorry for my bad English. I joined the forum to learn more about DAC and Speaker design. Thanks everyone

Hi all

I am on a learning curve, and made my first speaker measurement today. I followed the great guide on Audiosciencereview Link on how to make Quasi-anechoic measurements with REW.

My aim is to get experienced with the needed measurement techniques, before i jump right into building my first speaker builds 🙂

I got the best measurements with the distance of 50cm, but all guidebooks recommend 1-2m. Gated window allowed ~5ms. I am sure i can improve that with better placement, and increased dampening in the room.

I would be happy with your feedback, tips & tricks etc.

Hello,

Anyone have access to the proper passive crossovers or schematics for the BM12CXA + BM-D440 compression drivers?

This is a coax 12"


thanks!

It is any other OPA equivalled with 2068DD?

ZD3 like new . in retail box. two sets of op amps, pair of xlr cables $133

CANARE 4S11 speaker cable. New. I have two lengths. one is 12 feet so you can make a pair of 6 feet speaker cables. the other is 24 feet so you can make a pair of 12 feet speaker cables. both are NEW. 4S11 comes in two colors black and gray. mine are gray. $88

Quantity = 3 Dayton Audio Designer series Paper cone woofers 6.5 inch. two are tested and are in perfect cosmetic and functional condition. one is new. all three are perfect.
https://www.parts-express.com/Dayton-Audio-DS175-8-6-1-2-Designer-Series-Woofer-295-428?quantity=1

quantity = 1 Dayton audio measurement microphone NEW.
https://www.parts-express.com/Dayton-Audio-EMM-6-Electret-Measurement-Microphone-390-801?quantity=1

Bundle of random DIY components
1- Quantity = 6 WBT RCA connectors
2 - quantity = 2 DC power connector large
3 - quantity = 2 DC power connector thin
4 - quantity = 2 DC power connector medium
5 - 20x 1uF mica capacitor for power supply
6 - power on/off switch with LED indicator
7 - power on/off switch with LED indicator
8 - brass ground connector
9 - quantity = 4 ceramic tube connector
10 - aviator connector for building DC power supply 4 pin
11 - aviator connector for building DC power supply 2 pin
12 - quantity = 2 IEC power connector with fuse and on / off button
13 - big AC power distribution with usb A and C
14 - gold plated copper sliding connector with shield around 40 quantity

everything together: $111 shipped. I only accept paypal friends and family

Hi All

I am looking to buy 4x AD1862 chips and 2x PCM63 chips!

Cheers

Seb

Hey everyone,

I grew up installing car stereos in the late 90's building custom enclosures, going to sound comps, car shows, etc. I've been out of it for a long long time but with a recent newer car purchase, I find myself hating the "premium sound system". So here I am to speak to other car audio enthusiasts, and get ideas on how to perfect a very complicated stock system. I also love reading posts on the latest and greatest home audio and studio audio equipment.

- Jeremy

____________________________________

(last revised 27-july-2022)

Advanced & comprehensive miniOnken plan-sets for the Mark Audio & for the new Fostex FFxx5wk are/will be available for a subscription fee. Not all are as complete as i'd like (and even those that are will keep growing) and some have grown so fast they need reorganization (so please excuse that).

Available for the [CHR70 (all)/CHP70.2/CHBW70], Alpair 6.x, Alpair 7.x, [EL70/Pluvia Seven/CHP70.1], A10x, A12/12p, A12pw & Fostex FF85wk, FF105wk (which includes a set of mods to use FE103 SOL), FF125wk. Some FF165wk plans exist (same as A10p enclosures (with adjustments) so more can be quickly done) FF225wk under development (based on same enclosures as Alpair 12pw).

Rectanguar & trapezoid miniOnkens with vents on the side, simplier Classic Golden Ratio, and Compact Floorstanders are included in the plansets where appropriate. Custom designs done to cover client needs are also included. Other variations for wall mounting, more centres, and dedicated mid-tweeter use. And more. Included are details (where appropriate), cut-plan suggestions, tips, visualizations, and other information wher eit is useful.

Many enclosures have been standardized, with vent & driver details changing as needed. For example there are 6 widths of trapezoids (so far) with height changing to accomodate different volumes.

Plans are not a 1-shot deal, but a subscription (except for the Monster miniOnkens). I am always adding to them, and doing updates for specific clients (ie if you have available material that is not a thickness i have already done drawings for, i will generate plans for that thickness, or if you need a variation of a box to fit a specific need). Plans are also updated as questions & suggestions come in. There is much work to do, but any specific client needs will be taken to the top of the queue.

CAD plans for specific pdf pages can be provided on request.

Plans will be revised as needed for when drivers are revised.

Plans based on Mark Audio drivers are $25 USD each for EL70/P7, CHR/CHP/CHBW, A6x, A7x, for A10x, for A12x, A12pw. A subscription to the entire series is $80.

Plans are $25 USD each for FF85wk, FF105wk, FF125wk, FF165wk ar ein place & FF225wk is under development and will be the same price, A subscription to the entire series will be $80.

Tandband W8-1772 $25

HiEnd miniOnken plans for Lowther PM6A/C, Voxativ AC1.6, Tannoy HPD 385 are $50

Condensed plans (single drawings in most cases) for the Monster miniOnken series $10USD:
for Goodmans Axiom 201, Diatone 810 II, Dayton PS180/220 , Eminenence 12LTA, Tandband W8-1808, Tannoy Gold 12", Tannoy 385, Audio Nirvana 10 Cast Frame, Audio Nirvana 10 Neo, Airborne 6.5

Sealed box for ScanSpeak 32w-4878T $25

Canadian clients add appropriate GST/HST.

Plan-sets for other drivers will be done as appropriate drivers (ones we like and think are good value) come along.

The 1st paid planset was going to be for the Fonken with FE127, but the discontinuation of the driver stalled that one. That planset, as far as it got, is available on request for free.

dave

Hi folks,
I'm planning a small new pair of speakers for my desk.
The design of the “µMar-KenSET” appeals to me (size / appearance) and also the driver used.

Can anyone tell me where the F3 is, the bass is sufficient for desktop use and whether the cabinet would also be suitable for coupling a tweeter from approx. 1000hz?

As I'm new to the forum I can't write to anyone directly yet, maybe planet10 is reading along and could get in touch with me regarding the construction plan.

Best regards 🙂

Quite a few recent line-level projects here on diyAudio, are using Switch Mode Power Supply ("SMPS") wall warts to convert mains AC into the DC needed by audio circuitry. To name a few recent examples, the Starving Student II headphone amp, the First Watt H2 effects box, the B1 Korg NuTube preamp, and the Amp Camp Preamp+ (with headphone amp) are all powered by external SMPS warts. It's definitely a trend.

However, the 50-350 kilohertz switching circuitry inside SMPS modules, does make some members nervous. These folks are very concerned that high frequency noise on the DC supply, could compromise the sound quality of audio circuits. They desire a DC supply having very little high frequency noise, or, ideally, none.

I felt that, IF these pieces of audio gear could tolerate an additional 100 - 150 milliohms of resistance in series with their DC power supply, THEN we can build passive filter circuits to eliminate much of the SMPS high frequency noise. Admittedly I only studied their designs briefly, but I did come to the conclusion that all of SS-II, H2gen, B1Korg, and ACP+ can indeed tolerate an extra 0.15 ohms in series with the DC supply. So why not build a filter with a little extra series resistance, and see what happens.

After some experimental tinkering, the circuit schematic in Figure 1 took shape. It has two stages of LC filtering, built 100% with through-hole components for easy soldering. Noise attenuation at 50 kHz is about 40dB (i.e. 100x); while at 200 kHz, noise attenuation is about 65dB (1700x). Input to output DC resistance is about 100 milliohms on the PCB. Then we need to add the resistance of external wiring (about 16 milliohms per foot for AWG-22).

The filter circuit is laid out on a small PCB, 35mm by 40 mm (Figure 2). After stuffing, soldering, and attaching I/O connectors using blue and white "fly wires", the PCB looks like Figure 3. The first prototype unit was mounted inside a half size Altoids (breath mint) tin, using Kapton tape to electrically insulate the metal box from the rear face of the PCB. Then a piece of double sided foam tape keeps the PCB firmly attached in place. See Figure 4.

After the board is seated inside the enclosure and the I/O wires are pulled into their final position, two generous dollops of hot-glue are applied where the wires pass through holes in the enclosure. The glue keeps the wires fixed in place, and reduces the chances of abrading or scraping off the insulation.

When ordering the PCBoards, I told the fab to build them extra-thin: 0.6mm. This didn't cost extra money, and it seems not to have slowed the order's speedy progress through the fab. Figure 5 is an ungainly attempt to show just how slender the boards truly are. After all, the thinner the PCB, the smaller an enclosure it can fit into. Since it costs nothing to build extra-thin boards, why on earth not?

With this PCB and these components, the design limits are 48 volts maximum and 3 amperes maximum. You shouldn't exceed 48V, no matter what the current. And you also shouldn't exceed 3A, no matter what the voltage.

Speaking of components, here is a Parts List. It's plain ordinary text holding comma separated values. You can copy and paste it into a file on your computer, and then MacGyver the data into any format you wish. Surprisingly, there is even a Wikipedia article about MacGyver.

PARTS LIST


A quick note on DC barrel connector plugs and jacks: the individual parts sold by Mouser and DigiKey, have unusually small solder-lugs to connect external wires. That's because these parts include a removable, screw-on housing which takes up valuable space. {Unlike high volume wall warts, whose plugs are simply molded plastic} So the Mouser/DigiKey plugs and jacks only accept smaller diameter (lower current!) wires. Tinker with them and decide whether you find them acceptable. If not, you can buy thick 2.1x5.5mm (and/or 2.5x5.5mm) extension cables, then cut each end to 15 cm length. Amazon also carries individual cables with quite hefty (AWG-18!) wires attached to plugs or jacks. Here is an example to start your search adventure (the first link) But honestly, there's a fantastic implementation in post #935 of this thread that is worth considering.

This filter circuit includes polarized (electrolytic) capacitors and a unidirectional diode. Thus it only works correctly when the input is positive with respect to ground. Most SMPS wall warts are arranged this way, with the center terminal of the barrel jack "Positive" and the outer ring of the barrel jack "Negative". However, a few pieces of audio gear {I'm looking at YOU, pioneer batch B1 Korg NuTube preamp!} have chosen to make the center terminal Negative and the outer ring Positive. For those weird situations, be VERY VERY careful to route the IN, OUT, and GND terminals of the SMPS filter PCB, to the correct pins of the barrel jack and barrel plug.

Ingenious builders, I am confident, will dream up amazingly clever ways to mount and package these PCBs -- in astonishing configurations that bear no resemblance to a pedestrian candy box. The nicest thing you can say about half-size Altoids tins is probably, "they are both cheap and easy to obtain." Innovative, talented people will do better, astoundingly better I'm sure. edit- and my prediction came true, see post #935 of this thread. Thus I request that you disregard half-size Altoid tins and please DO NOT CLICK the following link (the second link)

The unique identifier for this board is "PO89ZB" followed by "-A" indicating revision A. I've put that identifier into the thread title, for easier searching in future months or years.

Gerber files for the rev-A PCB are attached; anyone can send these files off to a PCB fab, and get as many boards built as they like, with my blessings and good wishes. Please consider giving away or selling any excess boards that you've accumulated, to other members of diyAudio.

HOWEVER, rev-A does not include mounting holes on the PCB. Member carsten.witt has modified the Gerbers to create a PCB which does include mounting holes. These Gerbers were used to build the boards & kits sold by the diyAudio Store. Please visit post #407 of this thread (here is a LINK) to download Gerbers WITH mounting holes.

_

Hello everybody!

I was recently given this amplifier, an Optimation PA-250AC, and I would like to know if any of you all know anything about it. As far as I can tell, it is NOS, or near NOS. It even came in its original shipping box! I also have all the tubes for it and the manual. First of all, this thing is a monster and weighs in somewhere around 90 pounds. According to the manual, it is a lab-grade audio amplifier, capable of delivering 250 watts at 0.01% THD! At reduced power, the frequency response is 5 to 100,000 Hz. It takes 8 EL34/6CA7s on the output stage. It also has 3 impedance outputs, 3.75, 15, and 60 ohms. It's also capable of delivering a constant-current or constant-voltage output, and the meter can measure the output voltage, output current, or the plate current of each individual output tube. It uses both negative and positive feedback to keep distortion to a minimum, and even has overload protection. Overall, it sounds like a pretty amazing amp. Also, the front panel is hinged so you can easily access the circuitry. I know tube amplifiers pretty well, but this thing is far more advanced than anything I'm familiar with.

I've included a few pictures of this beast that I took before I installed the power tubes and played with it. First of all, it sounds incredible! It goes down to 5 Hz with ease, and it has power to spare.

If any of you know anything about this monster, or have had any experience with one or something like it, please let me know! Apparently it's pretty rare, since I couldn't really find anything about it on ol' Google, but just because something is rare doesn't mean it's worth anything.

Hi, I live in the Boston area. I have a CJ amp and an LTC Aero dac, wharfdale bookshelf speakers, and a very ancient Myriad CD-100 player, all of which I love. I am building a Tubelab SSE amp. I have all the parts and am doing final assembly and check out. I am also interested in the Nelson Pass Nutube amp, bc it represents a resarection in tube technology. I would be interested in audiophile meet-ups in the greater Boston area. Curtis

Hello. I am retired and live in the greater Boston, MA area. I started updating my stereo system (still playing vinyl) and am looking for info/advice on items such as amplifiers, phono preamps, DACs and other ancillary equipment. I began this project when I recently inherited a six-tube(?) amplifier built from a kit. Completed, I think, except for attaching the case covers. When get permission, the first question I will ask is "How long a stick should I use first time I turn it on." Thank you.

This is the Audio Precision System One SYS-322A Audio Analyzer, this is the dual domain DSP version where you can test both analogue and digital signals, as well as DSP FFT Spectrum Analysis. In addition with Burst option you can generate additional signals like Square waves.

It also come with both APIB PCI card and USB Adapter (adapter alone already cost $375) from Duke Aguiar (ex Audio Precision engineer), his USB Adapter even works on my Windows 11 PC (also tested working via Parallels Desktop (Win11) on Mac M1 Pro).

Despite its age its still a very capable equipment, Stereophile uses same model for their measurement before upgrading to Audio Presion SYS2722. Even British Loudspeaker Manufacturer ATC still uses it for their active speakers amplifier testing: .

Originally bought used directly from USA and still in working condition, convertible to 100V, 120V, 230V, 240V Mains voltage.

I'm located in Kuala Lumpur, Malaysia.

Asking for $1850 (negotiable) + shipping fee (depending on your location, I will try quote with both EMS and FEDEX shipping fee)

If you have any queries feel free to reply here or drop me a message ;-)

Hi, i don't know if this was done before but i made a improved version of the classic TMB tone stack making it a bit more versatile, this version has few tweaks to make the treble pot more useful and independent from the middle potentiometer, for example, the frecuency response isn't flat anymore when the mid is up and the rest at 0, now the treble can boost and roll off high frequencies. The middle control now attenuates ~25 dB compared to the 15 dB from the original circuit, also the bass control is more noticeable now thanks to the better frecuency separation from the rc filter.

How does it work?, is pretty simple, C1(the 470pF one) and R1(33k) are now two T high pass and low pass filters, this separates the highs and lows so the controls affect only the proper frequencies. R3 Bleeds the low frequencies
from the treble pot when its necessary, if the bass knob is up R3 is off so more lows and mids stay in.

It maybe good for mods because you keep the pots the same values, you just need to replace and add some resistors and caps.

I hope this can be useful to someone that doesn't like the original TMB stack 🙂, personally i think its more practical and sounds better but that's subjetive, if you try it any suggestions will be very appreciated.

Green : New
Blue : Old

30 years old guitar player here also novice electrician. I like enjoy fixing stuff but this time I need help. My amp is not in a good condition I read 33V dc on speakers.. Ouchh..

First it was only one resistor that burnt by plugging the amp, after changing it then others smoked, then I noticed the wire going to power transistor is deattached. I replaced old tip29/30c's with modern 40/41c's, 204/207 pairs with also 547/x pairs, 2n3373 changed with mj15003 but I am still hearing the buzz and It's still 33V dc at speakers... What is wrong bias? I am just tired. I double check transistors BCE, EBC all right, I don't know what to do anymore... Feeling overwhelmed.
Amp is HH vs musian 100
At first I lost that 10 R at the 48 volt supply then bias one, then 1k feedback resistor... I am open to suggestions..

I have been in the process of resurrecting my old SAE 3CM amplifier. It's been more problematic than I expected. It hadn't been fired up for 30+ years so I bought a re-cap kit and swapped out all the electrolytics before I punched the "on" switch. The re-cap job went OK, although I first had to un-do some "improvements" the previous owner had done. Like remodeling old houses, you never know what you're going to find once the studs have been exposed.

Initial testing after the re-cap job looked OK -- the driver board's idle-current measurements were good and the output voltage offsets were reasonable and could be adjusted to a few mV.

But longer-term operation revealed a problem in one of the channels. The output would limit on the negative portion of a test waveform (1KHz sine). And I also observed that the bias voltage went down, from the normal ~2.1V to about 1.85V. I suspected a problem in the Darlington VASes so started my troubleshooting by measuring the emitter resistors on the Darlington emitters (R24 & R25, see below). The 3CM uses symmetrical NPN/PNP LTPs that drive two Darlington pairs, one for the + side and one for the - side. So there were two emitter resistors to measure: and BOTH measured quite high. The schematic indicates that the resistors should be 62 ohms. The one on the + side measured over TWICE that, and the one on the - side measured about 90 ohms! That is far beyond the 5% tolerance the SM specifies for those guys.....

For a sanity check I also measured the 10 ohm resistors that are used to isolate the driver board's supply busses from the output board supplies. They were spot on.

I also measured the emitter resistors in the "good" channel and they also measured high, although not as bad as the failing side. The SM indicates that the R's are carbon film types. Visual examination didn't reveal any indication that the resistors were subjected to excessive current, and I didn't see any obvious mechanical damage.

In normal operation those 62 ohm resistors should be dissipating far less than 1/2 watt. I think they are that size so they will survive if/when a short circuit condition occurs & Q11 or Q12 turn on.

I'm puzzled why the resistor on the plus side is the worst, but the output waveform clips on the negative side. That channel initially works -- more or less -- but then starts clipping after it's warmed up. So there may be a thermal intermittent situation. My next test will be to monitor the resistances while I heat them with a hot-air gun.

The main point of this post, however, is to ask folks if they have seen a similar problem with old carbon film resistors spontaneously failing like this. If not, there's a good chance something else is going on that is over-stressing those resistors. The other thing is: if those went bad simply due to their age, it doesn't bode well for the other CF resistors in there. And there are a lot of them. Replacing all of them is not my idea of a fun time.....

Mark

PS driver board schematic below:

I somehow stumbled into diy again after nearly 25 years have passed since my last project. On an online market I came across a guy, who had started to build up an Nelson Pass F5T V3. The project was started together with a friend of him, who unfortunatly passed away. Because of this circumstances he didn`t want to work on this project anymore. Since I`ve been always attracted by class a amps, I decided to buy from the guy what was already there and to finish the project. By searching the internet for scematics and more information about this amp, I came across the forum and joined as a quiet reader of the threads regarding the F5T some weeks ago. As I need a good preamp too, this led me to the BA3 threads and currently supplies are coming in with the material I`ve ordered. My plan is to get everything done during winter and I`m really eager to hear the difference to the 6550 push pull tube amp I use right now. Of course I hope to get some help from all of you here if needed. 🙂 thnx in advance!

I put this speaker into a winisd simulation, but at a port of 40 hertz it tells me that the port should be one meter long.

The recommended box for according to the simulation is 25L, which seem to be too small.
I try with 80L , but still not good result .

Thank you !

Looking forward to getting some advice and sharing some thoughts on this forum.

Elektor has in time past published two hi-end preamps using MAT02 and MAT03 dual transistors for the differential pair using +-15volts supply; one was with a DC offset nulling preset somewhere in the negative supply line and the other was with a servo using OP77.

I have somehow lost both the Elektor issues but would like to have the schematics. I have three assembled boards of the one with the servo. I would also like to try out the easier offset nulling arrangement.

Could someone please send me a scan of the entire articles OR if someone wants to sell their copies of Elektor containing the above, I will gladly buy them.

Thanks,

The inexpensive 12" Peerless SLS woofers work really well in Ripoles. In fact; the SLS 12 is my all-time favorite $75 woofer.

I regret to report that the Peerless SLS 12 and XLS 12 woofers are no longer available at Parts Express without a 100 quantity min-buy. I called Parts Express about this and was told that the manufacturer (Tympany) imposed the 100-qty min-buy, not Part Express. Apparently; these woofers are being phased out but I don't see any comparable replacements for them on Tympany's website.

The discontinuance of these woofers seems non-sensical to me-- rather like Logitech discontinuing their Transporter streamer.

If anyone is interested in doing a group min-buy; count me in for ten.

Hi everyone,
I am 21 years old and will finish carpentry school this year in Amsterdam. I started enjoying sound systems after going to a party of kantarion. I was pulled in to the world of sound en subwoofers. I started cooking up a plan in my head of what I wanted. I knew it needed to be bass heavy but also pleasant for the ears. In the 3 years my school takes I did multipel internships. one was at Solosound. This is an electrostatic speaker maker in the Netherlands. This is where I learned to really listen to music and what it takes to make it sound good. sadly you can not use electrostatic speakers in a club setting because of the moister that builds up from sweating people. An other internship I did was at the Fiction Factory, this is where I learned to use a 5 axis cnc.
I was talking with IVCU from kantarion about what kind of tops I wanted and my first idea was the classic X-tro. but ended up choosing the JMODS from John White. this was because I liked the idea of a meh. I still have acces to the cnc and I already used it in a prototype I made of the meh jmod. was super nice to do all the weird angels easy peasy with the saw on the cnc. so now that I choose the tops I was looking at what kind of sub/ kick bin. JW did say in the paper that a kick bin won't be needed but I am planning on mostly playing EDM so kickheavy music and what I like about kantarion is the punchiness.
I was looking into the NNNN sub that goes down to 16 hz and was like yesss infra subwoofers is what I want. After some digging I found the Mforce drivers from powersoft. I looked at them and was like what the f*ck is this. got pulled into the idea of a system that is really special. so I contacted a distributer that had them. he was super nice and gave me the email of ALL, he is working on a diy design for the mforces. Went to visit ALL this weekend and was super nice talking to him and sharing details. because I still have acces to the cnc I am planning on making multipel prototypes out of mdf for the MFORCEs. (the tapped horn of ALL, standerd EDM sub and DV sub from powersoft.) currently writing this is the car on our way back to nl with the Mforce drivers in the back. I am here on diyAudio to share my findings with everyone about the drivers and the measurements from the boxes, about the road I am taking for the system. (also get some help if I don't understand anymore.) did not choose on kick bin yet because I maybe want a 2x15 or a few singel 18s, this will all depend on how loud the big boys wil get. I will be in Milano the next few weeks for the design week, wil start building end of April. Will keep everyone updated.

Hello, I'm Josef from Austria.

I'm an avid audio enthusiast. I've built speakers (Linkwitz LX531.4) and would like to build an amplifier for them. This forum is ideal for expanding my knowledge, and I look forward to sharing my experiences!

Thanks, Josef