I suspect this topic is covered dozens of times, but I couldn't find the answer I'm looking for.

So I have a speaker design that, in any case, woofers will be crossed to a horn around 800 Hz. This is constant. I'm either gonna use a single Faital 12RS430 in a 70L ported box and have decent F3 and 800 Hz covered, or I will use a woofer like Fostex FW 305 in a sealed box and use a second woofer starting from 100 Hz to the low end.

My question is about the quality of this 100-800 Hz. Which one might sound better? More resolution. The goal is not higher SPL, just more mid/low-mid clarity. Using a low Mms midwoofer vs. a heavier woofer (although Faital's Bl/√RE is higher...). If you have any woofer suggestions that can beat the FW305 in an even smaller box, please don't hesitate.


Thanks for the answers in advance!

Which are the interesting tubes available in mesh plate versions? I'd nominate the 27 and AZ1 or AZ11 as ones I've used and liked for instance.

Any explanation why mesh plates sound good?

Hi!

I felt that i might share my Troels Gravesen Revelator 851 speaker build and share my experience with the finished speaker when they are done so here we go.
Link to Troels project page: http://www.troelsgravesen.dk/Revelator-851.htm

Troels is a quite reputable DIY speaker builder from Denmark. Lots of useful information on his website and I can highly recommend it.

This is not a cheap build. It consist of a bass driver and midrange driver from Scanspeaks Reveleator series and tweeter from Scanspeaks Illuminator series. Crossover components are from Jantzen audio. It is made of 21mm birch plywood and Valchromat MDF for the front baffle (Valchromat has a very high density). Total cost is somewhere around 4000 US$.

Unfortunately my phone broke and a lot o pictures from the early stages of the build was lost expect a few that I had uploaded to my Instagram.

My original idea was to stain them black so that you can see the structure of the birch, but in my tests stains it turned out quite bad and ugly so I decided to paint them black with a high gloss finish. Birch is very nice in as it looks but do not fit in my home.

Single End Class A, we can see often.
What do we really mean by saying some amplifier is SE?
What is the opposite?
Is there amplifiers with SE in class AB? Or not?

This should not be confused with single supply vs dual supply.

So I have a story. Many years ago I had a Kenwood KA3500 integrated amp and enjoyed it for about 10 years. For some reason I decided I needed more power and read a Stereophile Article that favorably compared a Carver amp against a very expensive tube amp. After reading the article I decided to buy the amp on Sterophile's review and it was also on their list of recommended components. I hooked it up and listened and was sort of disappointed. Especially with the bass (a little flabby). Then I decided that because I was using the preamp output from the Kenwood, I needed a dedicated preamp. SO I bought a Rotel preamp. I don't remember hearing much difference. I know this isn't exactly DIY, but I am just curious if anyone else has had a similar experience. It was a rather expensive lesson. (buying something based on a review in a magazine).

BURNING AMP 2025

Twenty-Twenty-Five! I can’t believe it! Another Burning Amp Fest is booked and preparations are being made, this one is going to be great!

October 4-5. Petaluma Community Center (same place as last 2 years, the space is really good for our event 🙂 )

320 N McDowell Blvd, Petaluma, CA 94954


Details to follow. Watch this thread.

Looking forward to seeing you there!!

Dears,
This is sub-thread of my turntable post: https://www.diyaudio.com/community/...eded-with-motor-and-drive.412984/post-7687982
It seems appropriate to open new one just for the preamplifier.
Since I'm waiting for motor parts to start significant upgrade of this 22 y.o. thing, I will revisit the preamp too.

So far I was using this design with 2 x SSM2017 in first stage and 2 different second stages, description is here: https://www.diyaudio.com/community/...eded-with-motor-and-drive.412984/post-7688045

For the new version, I have 3 personal preferences that I would like to respect:

• Fully differential, I see great benefit and improvement from dropping ground of the signal path. Even still I'm using GND for referencing output voltage, but in new design I'm considering bootstrapping that with very low noise amplifier.
• Passive RIAA EQ
• As high as possible first gain stage, 60db (1000 V/V) seems just fine with my 0,34 mV nominal output cartridge. I do use higher PS voltage to allow for more output possibility; now +-18, next +-20V. This leaves second stage to deal with only about 20db gain.

Right now I'm making upgraded PCB with same concept, SSM2017 remain as input, second stage upgraded to OPA828.
SSm2017 specifies 0.012% THD+N at gain of 1000, I probably get it bit better as 2 amps in differential configuration will cancel some distortion. However not the best in class THD, nevertheless doubt if it is hear-able. Nevertheless SSM2017 as ancient as it is, is still unbeatable on noise performance.
Here is PCB work in progress:



Alternatives (in my thoughts) for the first stage :

2nd option is to keep configuration but to upgrade SSM2017 with better INA like AD8429 for instance, as used here https://www.diyaudio.com/community/threads/chipomatic-balanced-input-riaa.331009/post-5627780 (but this is single ended output)

3rd option is classic differential receiver (same as my second stage now) , but that would call for 4 x AD797 and cost of over 70 Euro, I see no other opamp that would fit this purpose.


4th option is to use this ancient schematics and replace each AD797 with it in above schematics. Probably that is as far as low noise is possible.
Matched low noise dual transistors are rare today, but there are many dual JFET's that would do just fine here. Of course some more modern opamp would be used instead of OP27. However, this design for stereo would call for 12 dual matched low noise transistors, quite heavy on wallet.



Or, 5th idea, this very fine simple circuit from John Broskie's site. Looks very tempting even the gain will be max 40db (x100), so second stage will need to deal with another 40db, but that is not major issue if below circuit is quiet enough.



I'm sure that each of these options will work just nicely (when fully developed), but what would be the best?
Any comments, thoughts, ideas?

Hello everyone

I have recently been in contact with Mr. Rullit regarding his exceptional field-coil drivers, and I intend to place an order for the nine-inch “Super Aero” model in the near future. At present, I am in the process of researching which type of speaker enclosure would best complement these drivers. However, I must note that my options are somewhat limited due to certain non-negotiable constraints—most notably, I am unable to accommodate large horn systems.

To provide some context: I reside in a historic manor apartment, where my dedicated listening room measures approximately 25 square meters (5 × 5 meters), with ceilings reaching a height of 2.7 meters. My musical preferences primarily include classical and jazz repertoire, ranging from solo performances to chamber ensembles and full orchestral works. As an amateur pianist, I place a high value on natural sound reproduction—one that conveys holographic depth, dimensionality, and body, while offering a rich and organically pure tonal character. From my impressions, Rullit’s drivers seem to embody these qualities remarkably well, particularly in terms of transient speed and natural timbre. The sound is airy but has body, it is transparent but has character, it is neutral but has depth. In order words it has the emotional realism that I strive for.

As mentioned in my introductory post, I am quite new to DIY audio projects. However, I have allied with skilled people —one of whom has experience with CNC machining, and another who excels in veneering speaker cabinets with real wood finishes.

From my conversations with knowledgeable individuals, it appears that Rullit drivers are well-suited to a variety of enclosure types, including dipole, front-loaded horn, open baffle, and resonant designs. Personally, I am inclined toward dipole or resonant enclosures, primarily due to their more manageable size. Unfortunately, I believe my room is too small to accommodate horn systems effectively, and open baffle designs would require substantial space behind the speakers, which is impractical given my current interior layout. I have attached photos of possible solutions.

I would be most grateful for guidance and recommendations that could assist me as I move forward with this project. Even specific design plans would be perfect! Any reflections, suggestions, or insights would be sincerely appreciated.

Thank you very much for your time and considerations

Hello EL34 Baby Huey builders,

As suggested by SCD in the following thread : http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 I am starting a new thread specially dedicated to the building of Baby Huey amplifier based on my PCB which has been produced in more than 330 pieces and is still requested by many tube amplifier fans in a possible future Group Buy 4 : http://www.diyaudio.com/forums/group-buys/312869-gb-baby-huey-pcb-42.html 🙂

I will put in this thread all the information available about the assembly of the EL34 Baby Huey amplifier and some of the auxiliary board that I have used or designed to add some features to the amplifier. I must tell you that I am not in professional amplifier business, this is just a time consuming hobby for me and, as you will see, English is not my first language and I have sometimes difficulties to explain things correctly, sorry for that but at least you will understand easily schematics, pictures, B.O.M., etc... 😀

History

All that started about two years ago when I read the http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 post from "gingertube" ! As I was interested by the shunt feedback concept that I didn't know I wanted to test it and decided to build the simplest version with two PCL86 tubes. Since I am very bad in point to point wiring, I made a small PCB. This amplifier was so good that I decided to continue my quest and, since the ECL86 or PCL86 were unfortunately no more produced, I made a second PCB for the EL84 version which needed a third tube, a 12AX7 (ECC83) for the input stage and added MOSFET with current source to drive the output tubes. This amplifier was very good and I was very satisfied by the MOSFET driver stage, but I was also a little bit frustrated by the limitation in power, about 12 W, and the fact that I could not use different power tubes...

To solve this problem, I made an identical version but with octal socket to accept many compatible tubes from the 6V6 to the KT88 and the EL34 Baby Huey was born ! Following the presentation of this solution on the diyaudio forum some members asked me if I could sell the PCB, I had never done this before but since the moderator move this discussion to the Group Buy forum I have received several request and started a GB1 with a target of 50 boards but finally closed it with 80 PCB ordered 🙂 I had to send them Worldwide and to learn how to make PayPal invoice... Later others readers asked me for more board and I offered a second and "last" GB2 which finished with 120 boards ordered !!!

Later, since there was still a strong demand, I asked Prasi, to whom I have bought a CRC power supply PCB, if he would accept to manage a third GB and he kindly accepted 🙂 He also suggested to make 2.4 mm boards for better rigidity. Now 120 more boards have been ordered and are in production and there is already 20 PCB's in waiting list for a possible GB4 ?

Documentation

In this first post I will enclose some of the latest documents available for building the EL34 Baby Huey and I will add more in next posts depending of your questions.

You will find the updated BOM in the GB letter, the latest schematics, some building recommendations, how to connect and to adjust the amplifier and several pictures showing the PCB assembled on top side (big components go on bottom side), a 6CA7 board fully assembled in test and finally the EL34 Baby Huey in its enclosure nearly finished (two vu-meters are still missing).

More pictures and data will come from all the people who have built this nice small amplifier. It is a very nice project for those who have never made and listen a tube amplifier, but remember there is some lethal high voltage (up to 500 V) and you should be very careful when you work on it

Have a nice time building the EL34 Baby Huey...

Best regards,
Marc

I’ll go first. Which one of you guys did this?

As the title states, this is a thread dedicated to dome midrange drivers, specifically any larger dome driver at least 50mm or 2" in diameter intended to be used in a 3 way or larger speaker design.

Being there isn't a good collection of data on this rather rare type of driver and its use, it would be nice to have it all in one thread. My goal was to give anyone interested in the successful design of a speaker using a dome midrange a solid starting place to gather or share the info necessary to design a new speaker or to modify an existing design to use them ie. xover, baffle modifications, etc.

If you have any specific or technical info (measurements, graphs, data, xover design, pictures, links etc) regarding your favorite dome midrange or a specific technical question, please feel free to share it in this thread.

Please keep your post to the point and avoid any strong subjective opinions. I was hoping this thread could accumulate as much relevant info as possible. Thanks in advance for any productive shared info.

Introduction:
Hey guys, been a long time lurker here. I've been pretty busy lately working on a dirt cheap unity horn project for my desktop setup. The entire horn is going to be 3D printed for ease of assembly. A lot of effort has been put into making this build as cheap as possible. I actually think this might be one of the cheapest unity horns out there. I have two goals I want to achieve for this project.

1. Wide phantom image and constant directivity. I have lots of pc-monitors in-between my current speakers. The problem with this is it forces my speakers to be very far out from the listening spot (around 150 degrees). Unless you are seated perfectly between the speakers, the sound-stage collapses. It is my belief that a wide CD horn will fix this.
2. Provide an affordable MEH so that more audio geeks can hear these awesome speakers. I really love unity type speakers, the linear phase, constant directivity, and acoustic filtering provide a lot of benefits that are hard to achieve otherwise. My dream is to eventually make this into a diy kit, but I'm not sure if I have the resources to make this a reality.

Woofers:
This all started when I discovered these little Dayton TCP115 woofers. I was working around in hornresp and pasted the driver profile by mistake. Low and behold, the simulation had an extremely wide bandwidth for such a cheap driver. The high xmax is also nice for going low so I was able to make this design a 2 way and still get decent bass.

Tweeter:
Most, unity horns seem to use compression drivers. Since I don't need high output and need a cheaper option I decided to go with something different. The XT25 is what I am using for now and it seems to work quiet well. By using a really large horn I was actually able to push the crossover frequency quiet low (around 1.2khz). I know, I know, that crossover is insanely low for this tweeter. I have more data on why this works; will post more later. Right now I am having trouble getting accurate distortion measurements to confirm my theories.

Measurements:



Around 15 degrees off axis after some quick EQ. The dips at 6k and 10k appear to be from a problem at the throat which are being fixed in the next version. The next box is also going to have a flush mounted horn and 18mm round overs on the baffle. I am hoping this will improve those ripples. You can't just EQ those ripples at any one angle. As you can see the dips move around depending on your angle off axis.



1/3 smoothing of the same graph. I don't know what the exact angles are, it's really just a proof of concept to show the directivity is being controlled. The light green line is around 60 degrees, which is why it is so low in level.

Things I still need to do:
Throat optimizations, active xover tweaking, passive xover development, take more accurate polars outside, measure below 200hz, port it (maybe?), make it pretty.

Hello

Just to note ... My only phono preamp that I use every day is the JLH shunt feedback design
so decided to build another project as a direct comparison to see if something is better

I was told this design could cause scratchiness in the pot because of loading and after about 4 months of use it seems that may be the case.
I'm seeking advice on two changes I was considering.
Replace the conductive plastic Alps RK27 (from Ebay so probably a knockoff) with this Vishay cermet, and swapping out the LM4562 with a FET input OPA2134 to reduce the pot load. I know an OPA1642 would be a better choice but it's not available in DIP8.
Output stage shown.
VR4 is 50K so R112/212 is 6k8 and R113/213 is 15k, per Rod's instructions.

Push-pull EF or 2EF output stage is probably the most frequently used output topology in class AB amplifiers. It is well covered in renowned design handbooks, like

Self, D.: Audio Amplifier Design Handbook (Newness)
or
Cordell, B.: Designing Audio Power Amplifiers (McGraw Hill)

Authors come to the conclusion that for the lowest distortion in class AB, voltage drop across an Re resistor (usually 0.1 to 0.47 ohm) should be about 22mV, as by Self below (he shows voltage between emitters, i.e. 2 x Re resistor):



Simulators (MicroCap, LTSpice) show +/- similar values. But how about real amplifiers? Is it a general rule? My experience says that sometimes yes, sometimes no, depending on the amplifier circuit.

I am posting an example of the amplifier where this general rule does not work. It is the remake of 1969 Sinclair Z-30 amplifier:



Re resistor (R14, R15) is 0R22. Optimal bias should be (according to Self) 23.1mV per Re. I have measured spectra at moderate power (4R7 load) for 8mV, 14mV and 21mV per Re, i.e. idle current 36mA, 64mA and 95mA. Below are the results.



The distortion is almost same in all 3 cases, slight differences are in high order distortion components. Something does not fit. Let's measure distortion as a function of output voltage and idle current:



And now we have it. It is something that we would intuitively expect. At low power, the higher the idle current, the lower distortion, because the output stage stays longer in the class A. The lowest distortion is for 50mV across Re, resulting in 227mA idle current. Now we are up to 0.48W in class A for 4R7 load (green trace). About 2.5x Self's optimal bias point. So? Isn't it better to design for lowest measured distortion, rather than follow textbook suggestions? And, BTW, this amplifier has flat THD vs. frequency up to 10kHz, measured with 90kHz BW.



------------------------

Edit June 15, 2025:
There were some remarks that the amplifer under test here above was a poor one. I agree, and for this reason I am posting results measured on another amplifier.

So, another amplifier, much better than the oone here above. 3EF topology, 0R22 Re resistors, one pair, 2 x 25V supply voltage, 4R7 load - conditions are same as before. Bias voltage across Re 9mV, 23mV ("optimum") and 40mV.

Spectra:


THD vs. output voltage into 4R7 at 1kHz and BW45kHz:



We have much lower distortion now, however the same result. The "overbiased" setting has lowest distortion at low power, at higher power all settings become equal.

I have posted some simulations of the Bliesma T34A in a waveguide designed for wide directivity to very high frequencies, and some renderings of possible cabinet configurations using the Purifi 6.5 Aluminium driver in some other threads.









I am now making a concerted effort to actually build something that I can listen to 🙂

Finding time to finish the CNC I have been building (for a long time already) is proving hard and apart from aesthetics, I can make something simpler in appearance that performs pretty much as well with the already working tools I have. So a basic box with roundovers and a 3D printed removable waveguide will be the starting point.

Something more like this apart from the colour.



In case it is not obvious to anyone, I should mention that Ath from @mabat was used in the design process for the waveguide.

I have one 3130 that is canibalized
made my repairs and replaced what ever needed but i have asymetrical cliping
Pos side starts to clip too early like 20 W
any hints ?
Blody schematic have no voltage reference VAS is supplied with about 36V after the resistor 35.4 Dont know if this is enough

Any ideas ?
thanks

Hi,

There are plenty of TPA3255 BTL amps available but 4 channel amps are almost non-existent.
As per the app note, the schematic of both 2 channel BTL and 4 channel single ended are different, but the BTL amp is completely differential, it looks like if we separate the differential input to single ended stereo input then we may get two separate outputs instead of 1 BTL output. If, this is the case, its easy to convert stereo BTL boards to 4 channel ones. I mean, INPUT_A goes to OUT_A and INPUT_B goes to OUT_B. Can somebody please tell me why its not a good idea?


Thanks,
Warm Regards,
WondefulAudio

Hello,
In a world of engineers i'm a tad shocked to don't see any good decoupling, the mecanical engineers are not all dead since i've recentely be teached by one of them and my last school teacher was also an engenneer (with a PhD in mecanics)... he was young 25 years ago.
People are using CAD and FDM printers here and no one seems able to decouple convenientely a loudspeaker, could you say what i don't understand ?

Aliexpress is full of strange spikes and ridiculous spring systems, are we all idiots ?

Here is a SMR for a microphone :

dynaco sca35 - having an output transformer rewound - should i do both?

I think about some comparative testing of different materials for the ESL63 dust protection purpose.

Background: Quite many posts in different threads are related to the dust protection film and it's potential impact on the impulse response of the assembled ESL63 speaker. Some advocate to omit this dust protection altogether, some claim no influence of the two film sheets, some fit them hands down for practical reasons while trading in a potential slight sonic drawback. I therefore would like to perform some comparative, more theoretical, yet systematic testing of some standard and also of some non-standard materials for dust protection. If the test succeeds, then a more precise weighting/compromizing might become possible for every of the tested materials.

For my refitted ESL63, I used Vliesseline stich n tear, which showed some quite pleasing results while measuring. I do not claim that it is the best compromize, and I don't know how it performs against other options. So I would like to test this product against some experimantal 100% PET felt sheets/panels and of course also against different brands and strengths of standard film ("standard" == routinely used as dust protection). It would also be interesting to test some, say 3 different brands and strengths of standardly fitted films one against the other.

To perform these tests, I need some samples. So my question/request to the pro ESL63 rebuilders here in this forum is: Are some of you experts willing to send me 1.5m of yours preferred and routinely fitted dust protection film? Of course I would pay for the material and shipping. Please contact me per PM for my shipping address and for the mode of payment. I will perform this test if I can get 2 or 3 samples.

Test setup would include the absorbtive and the reflective property of each dust protector candidate (DPC) under test. I imagine to place everything into a line:
Sound source - Mic - DPC - Flat/plane surface as near-perfect acoustic reflector. The mic would therefore catch first the wavefront of the direct sound, then the wavefront reflected by the DPC, then the reflected and twice partly absorbed wavefront. Reflected by the acoustic reflecting plane, absorbed by the DPC.

Any comments welcome.

Somebody have the files .zma and frd ir dxo for xsim for Satori MW19P 8?

I have been using a Sony DVP-S7700 as a transport connected to my Music Hall 25.2 Dac which has some slight mods, including Burson V7 Vivid opamps and a Gold Lion 12AU7 tube. Burson has been kind enough to provide me with samples for a new project to mod my DVP-S7700 and install DIP 8 sockets and replace the OPA2134 factory opamps.

Phase one has been completed, removing the soldered OPA2134 and replacing them with DIP 8 sockets.



Phase two is waiting on some DIP extensions from Burson, it's too tight to install the V7 opamps due to the location of some capacitors. This will hopefully make it easier to swap without having to remove the analog audio board every time.

Please follow along for future comparisons between the analog audio board with the Burson opamps compared to the external Music Hall 25.2 Dac using the Sony as a transport connected through CoAx. I will also be comparing the older V6 Classic, to the V7 and OEM OPA2134.

They sound, but to hear them and with an obvious problem in the medium-low range, you have to turn up the volume a lot. a lot!
is there any chance that they can be recovered? they asked me if I want to take them back at a price... but
I wanted to know from you if they are repairable and how complicated they are to fix.

3 sets of PCB for Parallel LM3886 EC/Comp Amp. THD+N<0.0006%, Noise10uV. (see my post and measurements)

4 layers 1 OZ, 1u Gold ENIG

25USD per set ( include two PCBs, schematics, a simple build instruction, BOM) plus post 10USD for US and Canada, 15USD for Europa.

Please PM

In 1977 I built a pair of transmission line loudspeakers, similar to the famous Webb design, but somewhat larger. When I went to graduate school in 1980, they were too bulky to bring along, so I sold them. Now, both myself and a friend from those days want to build a couple of pairs. So I'd like to locate a copy of the plans.

With that as an intro, does anyone here have a catalog or plans from the company that produced the kit? It was called Accurate Sound, and was at 1213 M Street, Lincoln NE 68508. Below, I've reproduced a copy of an advertisement of theirs, from the January 1977 issue of Audio Amateur, page 49.




Does anyone here recognize this, or have an old catalog or plans?

Cheers,
Bruce

When I was young, we spent hours on end playing what we called word game. Same rules but it was always 4 letter words.
I was introduced recently to this new sensation and tried it today. Now I know it's beginners luck, but first time out I got it in 3 words.
I think I'll try again and let it bring me back to earth.
Who else is doing this?

For years I've been pursuing a way of getting better stereo sound like you get when you use a divider wall between stereo speakers to eliminate crosstalk and interference patterns. One way to do this is to add more channels using a matrix. A simple and well known matrix is to turn L and R signals into L-R, L+R, and R-L. What no one has ever told me is that this simple array will do amazing things if you space the speakers apart properly and listen at an appropriate distance. Center panned sounds only play through the center speaker, so there are no interference patterns so that solves the phantom center problem. But what happens when a sound is panned hard to the right or left? For a right panned signal you end up with the array playing a -R in the left channel, a R in the center and another R in the right channel. This of course creates interference patterns, but good ones! They work to create the proper stereo separation and never cause a null to cross our ears! This is because there is a null in the center of the sound field instead of a lobe. So each ear gets an appropriate stereo lobe! Each ear gets a lobe - so punny!

Here's a picture of my current array using basic little Sony SSCS-5 speakers



You can see I'm actually using 5 speakers here. The center channel plays full range down to 100Hz. The inside left and right play down to 600Hz. The outsides play 600Hz and down. This just helps to boost the stereo effect as the wavelengths start to get long compared to the width of the array. 3 speakers works great. 5 just gives it a little something extra and I happen to have lots of speakers and amp channels available.

Watch this video to see how the interference patterns produce excellent stereo throughout a huge range of frequencies. I used Falstadt's great ripple tank simulator to demonstrate how the effect works over a huge range of frequencies. http://www.falstad.com/ripple/Ripple.html. The three dots at the top of the screen represent an appropriately spaced array of 3 speakers playing a hard right panned signal. The circle down below represents the listener's head with strong signal reaching the right ear and weaker signal that is phase delayed reaching the left ear - as it should be. As I play a wide variety of frequencies you can see that strong stereo separation is maintained and no null from interference patterns ever crosses the right ear. You do get some weakening of the signal as the frequency goes down due to the center null widening so you can boost up the side channels in the lower frequencies or add a wider spaced set of speakers for the lower frequencies. I actually do both.

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So what happens with slightly panned signals? The same thing except the lobes are not as different, so no matter the panning there are no unwanted nulls from the interference patterns at the listener's ears.

Also notice what's happening off to the sides - not a lot of energy to light up early side wall reflections.

So how does it sound? I'm elated! It's great! It's not phase-y or weird. The sound stage is natural and oh so clear and smooth with beautiful separation and clarity. It's a revelation. On recordings with wild stereo effects they get really wild like they should. I don't see myself ever going back to a two speaker setup for high quality stereo playback. I tried having the outside speakers playing regular stereo from 600Hz down and it's just a downgrade. This is MUCH better IMHO even in lower frequencies where it looks like it's falling apart and just turning into mono. It's blowing my mind.

As a general starting guideline I recommend spacing the speakers at about 1 foot apart center to center for the 3 center speakers and put the listening position about 8 feet back. You'll hear some good stuff with just 3 speakers but you may need to put a low frequency boost on the side speakers to correct the tone for side panned sounds. You can do this by playing correlated pink noise and panning it left to right. Adjust the lower frequencies on the side speakers until the pink noise sounds similar in tone and volume across left, center, and right of the sound field. Experiment with spacing and listening distance. It's surprisingly flexible.

One difficulty is how to setup the matrix array. I use my Mac mini running Audio Hijack to do it in the digital domain. This allows matrix mixing and access to all 8 channels of my Denon receiver over HDMI. You can do a basic 3 speaker array using a 2 channel playback system by creating a L+R signal for the center speaker and a L-R signal for the side speakers. I run the L+R signal into the right channel, and the L-R into the left channel of the amp. The left channel runs both side speakers in series or parallel. Just wire up the right speaker opposite of the left speaker and it works!
I don't recommend mixing line level signals in the analog domain unless you have appropriate signal mixing hardware that that properly buffers everything. YMMV but my results were lackluster just using Y-connectors. I also don't recommend hooking multiple amp channels up to the same speaker unless you really know what you are doing. If you are using low pass and high pass crossovers on the outboard speakers like I am, watch out for phase reversals. Suddenly your soundstage is backwards!

12/30/2022 Update. After trying a lot of things I'm back to just 3 speakers. With proper spacing and the voids filled in between the speakers to minimize edge diffraction this really produces the purest sound and best imaging. I think I was tricked by the increased overall volume of adding more speakers. So there's something to that. If you have a lot of the same kind of speakers lying around and they can't play very loud, 7 of them playing at once makes a noticeably higher playback level possible than just 2 or 3 of them, and you can get some really great imaging. Turning up the volume a little to make up for the fewer speakers and I'm actually hearing better sound overall. This is great news because it's easier to set up as there are no time delays required and so a simple 2 channel amp and 2 channel dac can be used to power all 3 speakers. You just have to get the stereo signal matrixed into L+R and L-R signals. I heard one person say that the electric summing and differencing causes irretrievable loss of information. It does if you just take the L+R signal by itself, or the L-R signal by itself. But if you mix all the signals, including the inverted L-R, which gives R-L, everything that should reach the ears does. And, much less of what shouldn't.

Hello, I have a problem with this amplifier. It's stuck in the protection. Everything's been repaired, and there are no more problems. If I remove the Q50 transistor (A1266), it runs smoothly and nothing gets warm. So I think there is a fault in the protection circuit . I already changed the tl494 and the lm293n out of suspicion and then it ran for about 15 minutes. Suddenly it started to turn on and off 3 times and then it hung in protect again.

I need help please

Hello DiyAudio community,

TL;DR: This is a USB transport for audio output (up to 8ch) and input (2ch for now) and user device control (e.g., DSP management) from PC (MacOS/Linux/Windows) thru I2C/GPIO. Including bootloader for remote firmware update, flexible device configuration, HID interface, multiple audio output options, integration with SigmaStudio (simultanious audio playback and ADAU DSP configuration). Compact module available in USB-C and USB-B versions, isolated or non-isolated.

Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

So, the story started when I needed a USB transport for audio output and another channel for device control, such as for managing DSP.

Last time, I solved this problem using a USB hub and a USB to Serial converter. This way, I assembled the required interface from 4 chips:
https://www.diyaudio.com/community/threads/audio-transport-module-york.406025/
(first post)

I tried to combine everything into one XMOS chip. This was also a working solution, but there was a big problem with the availability of the chips, especially in the desired package.

Thus, developing the transport on the pic32mz seemed the most logical to me. The first prototype module was based on Dortonyan’s project from Vegalab: in terms of circuitry, it almost completely repeated the original project and was designed for two-channel audio output, plus a serial interface. During testing of the firmware based on the original source code, several problems were identified when working in different OSs. The serial port was also not fully implemented.
I posted my version of the firmware with fixes in the original thread and on GitHub: https://github.com/eclipsevl/york_pic32mz_uac2_osfw/

After that, I continued working on the functions I needed. The following features were implemented:

1. Bootloader. Necessary for firmware updates via USB, without a programmer.
2. Flexible device configuration using a PC utility (which is also used for firmware updates).
3. HID interface for transmitting service information and device configuration. Initially, I planned to use the serial port, but HID is much more suitable.
4. Serial interface, which can be optionally enabled.
5. Various additional audio output options: s/pdif, 8-channel TDM, dual i2s (for using some DACs channel-by-channel in mono mode). Recently I also added support for old dacs with clock/data/latch interface. I.e. direct connection to dac ICs such as AD1862/PCM1702 etc is also possible without glue logic.
6. Various clocking options: module oscillators, external clock (slave mode), internal PLL clocking.
7. I2C port and library for integration with SigmaStudio: for simultaneous audio input/output and DSP ADAU programming.
This last feature is currently a unique combination and fits well into DSP projects: https://www.diyaudio.com/community/threads/freedsp-octavia.393804/page-18#post-7625685

The configuration and firmware update utility looks like this:

Device name and PID/VID settings


Audio interface settings:


Input of up to 2 PCM channels, up to 192kHz (384kHz with external clocking at 1024fs)
Output of 2 PCM channels, up to 192kHz
(384kHz with external clocking)
Output of 8 channels in TDM8 mode (up to 96kHz, clocked by PLL)
Output of 8 channels in 2xI2S mode
Output of 2 S/PDIF channels, up to 192kHz clocked by PLL



And of course, in the simplest version, this module can work similarly to any USB interface, in slave or master mode.
DSD has not been tested yet.


Photo of the module, second version.

The additional 4-pin connector can be configured as i2c/uart/gpio, and is also used for forced entry into the bootloader (in case of unsuccessful software update).



Available in two versions: USB-C and USB-B. The transport itself is quite compact: it fits into an area of about 2x2 cm - which is important for integration into other devices.
So I'm working on a smaller PCB with same functionality.

Later I'm going to release a software library to basically enable anyone to create their own app for PC to control custom devices: toggle GPIO of USB module/send I2C transactions.


The module is available with USB-B or USB-C, the price is 49 Euro.
For purchase PM me. Also available on Tindie:
Multichannel USB UAC2+HID+CDC interface York

I'm open for requests for additional features but whether it is going to be added to the firmware depends on hardware limitations and time required to implement it.

Latest version of config tool:
https://york.eclipsevl.org/york_config_tool.zip

P.S. Huge thanks to:
1. Alexey (Dortonyan) for publishing the project. His work laid the foundation, and without it, this project would never happen.
2. Beta testers of the first version: @CyberPit, @Ludilu

UPD Oct 28th 2024:
Documentation draft attached

UPD Feb 17th 2025:
Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

Hey,
Planning on building the Paul Carmodys The Pit Vipers.
Built a couple of amps and pre-amps with a lot of help from this amazing forum.

Recently got a workshop in my possession so I think its time to make a couple of speakers now when I have the space.
The plan is to make something quite simple and I found the Pit Vipers which seem pretty straight forward.

I do have a few questions though. (probably stupid)
1. What is the best kind of material for this kind of speaker? MDF?
2. The plan that Paul Carmody doesnt specify the thickness of the material. Can I just assume the thicker is better? Thickness would change the volume but not to any large extent.
3. He is using a 6" PVC end cap on the midrange. Wouldn't be better to make a proper enclosure?
4. How much damping should be done? All sides, top/bottom?

Hello everyone!
I've recently finished my vintage inspired 2-way design and figured I'd share the journey here for any fellow members who may be interested in the concept or even building it for their self.

Soooo. Let's see it! What is it? Kronos is a sealed 2-way design utilizing the SEAS A26RE4 10inch Woofer and the Visaton FRS 5x-8 2inch in a WG.



Wait, isn't that Visaton driver a full range? Isn't this more of a "WAW" design? Yes, the Visaton is in fact a full range driver but it's actually being utilized as a tweeter in this design. It's mounted in the Visaton WG and integrates perfectly here with the SEAS woofer.

Isn't there already a similar design for this woofer? The A26? Yes, there is. However the tweeter for that design is rather pricey at $350+ each, while the cost here is $14 for each driver and around $19 for each WG currently on Parts Express. (Other options available as well, see below)

Okay okay, enough with the Q&A, let's get into how this came about and details of the design.

Introduction:

The Kronos speaker build was born from a sense of nostalgia—rooted in childhood memories of sitting in front of my dad’s hi-fi system, mesmerized by the towering loudspeakers that filled the room with sound. Those classic designs, with their large woofers and cone tweeters, left a lasting impression. They had a presence—both visually and sonically—that felt larger than life. With Kronos, I set out to pay homage to that era and those experiences, blending the soul of vintage loudspeakers with the clarity and control of modern design. It’s a tribute to the sound that sparked a lifelong passion.

Driver Selection:

To bring the Kronos concept to life, I carefully selected a driver lineup that reflects both the spirit of vintage design and the performance of modern components. For the low end, I chose the SEAS A26RE4, a 10" paper-cone woofer known for its rich tone, effortless bass, and smooth upper response. It’s a direct nod to the classic wideband woofers of the past—capable of anchoring the system with warmth and authority.


For the top end, I went with a more unconventional approach: the Visaton FRS5X, a small full-range cone driver, paired with the Visaton WG 148 R round waveguide. This combination offers a controlled dispersion and a pleasantly natural tone that echoes the voicing of vintage paper cone tweeters, but with improved focus and clarity. To mount the FRS5X, I simply centered it on the waveguide and drilled my own holes—an easy but effective way to create a tweeter solution that stays true to the DIY spirit and captures the character of old-school designs.


Worth noting: With the rise of 3D printing and modern fabrication techniques, custom waveguides for drivers like the Visaton FRS5X are now readily available. For those looking for a more refined or drop-in solution, Heissmann Acoustics offers a purpose-built 3D-printed waveguide specifically designed for the FRS5X. It's a great option for builders who want to simplify the mounting process while maintaining the same compact format and controlled directivity.



Enclosure Details:

The SEAS A26RE4 woofer is housed in an approximately 85-liter (about 3.0 ft³) sealed enclosure, giving it ample volume to breathe and deliver deep, full-bodied bass with natural roll-off—true to the character of classic hi-fi systems. This generous internal volume helps the woofer operate efficiently without excessive low-end boom, maintaining a balanced and effortless presentation.


The Visaton FRS5X is isolated in its own 1-liter (0.035 ft³) sealed chamber. This small compartment ensures that the mid/tweeter remains unaffected by pressure changes from the woofer, allowing it to perform cleanly and consistently.


Throughout the cabinet, adequate internal bracing was incorporated to minimize panel resonance and structural flexing. The result is a rigid and acoustically inert enclosure that supports clean, undistorted output even at higher playback levels.



Crossover Details:

The Kronos crossover began as a theoretical layout, designed with target values based on driver behavior and desired voicing. From there, it was refined entirely by ear, with countless hours of listening and adjustment until the final values locked into place. This process allowed the system to reach a balance that felt natural, dynamic, and emotionally engaging—true to the character I set out to achieve.


The SEAS A26RE4 woofer, a modern version of the W26 used in classic designs like the Dynaco A25, has a naturally smooth roll-off that doesn’t strictly require filtering. That said, I chose to add a small 0.33 mH series inductor to gently tame the upper midrange, making the speaker more forgiving and enjoyable at higher volumes—reducing the risk of harshness or “shouting” without robbing it of presence.


For the FRS5X tweeter, mounted in a waveguide, no series resistor was needed. The waveguide not only improves sensitivity and dispersion control but also helps the FRS5X blend naturally with the woofer. Without the waveguide, I would have added around 1 ohm of series resistance to balance its output. The high-pass network is essentially first-order, using a capacitor for the main roll-off. A parallel inductor was added to keep the tweeter’s upper resonance from bleeding through—simple, but effective.


While a textbook solution might call for an RCL (resistor-capacitor-inductor) network for perfect impedance correction, I found that in practice, a single coil did the job just fine. An optional overall impedance compensation network was included for the sake of completeness, but it's more a nice-to-have than a necessity in this build.


In the end, the crossover reflects the spirit of the whole project—minimalist, purposeful, and guided by listening above all else.

CROSSOVER PCB:

To make this project more accessible for others—especially those new to DIY loudspeakers—I went a step further and designed a dedicated PCB for the crossover network. Rather than relying on point-to-point wiring or a perfboard layout, this custom PCB ensures clean, repeatable assembly and proper part spacing, helping reduce the chance of wiring errors and making the build experience more enjoyable.


The board is laid out with component footprints matched to the actual values used in the final design, and it includes clear labeling for easy reference. Whether you're a first-time builder or a seasoned DIYer, this PCB simplifies the process and makes it easier to achieve consistent results.


I’ll be including a download link at the end of this presentation with everything needed to build your own pair of Kronos speakers—including crossover schematics, PCB files, enclosure plans, and additional notes gathered throughout the build.



Finished Speaker:

Here’s a look at the finished Kronos speaker. Aesthetically, I realize this look might not be for everyone—but that was never the goal. I wanted the finish to reflect the spirit of the project: cheap, fun, and bold. The result is something unique, eye-catching, and artistic.


I’ve had a few people ask how I achieved the finish, so here’s a quick breakdown:

• I started with a roll-on bedliner called "Total Coat" to create a tough, textured surface.
• After that, I applied a Rust-Oleum yellow paint as the main color.
• For added visual interest, I used Rust-Oleum Black Marbling spray, which creates a random web-like texture and gives the surface a more dynamic, artistic feel.
• Finally, I sealed everything with a Rust-Oleum matte clear coat, which helps protect the finish and reduce glare.

It’s not a high-end veneer or mirror-gloss lacquer—but for a fun, rugged speaker with personality, it gets the job done. Cheap, effective, and satisfying to see come together.



Final Measurements:

Below you can see the final measured response of the Kronos design. The results highlight just how well the Visaton FRS5X in a waveguide and the SEAS A26RE4 woofer integrate—especially considering the simplicity of the crossover network.


The response is impressively smooth, with excellent tonal balance and a natural transition between drivers. The waveguide not only improves the FRS5X’s efficiency and dispersion but also allows it to blend seamlessly with the larger woofer, avoiding the typical disconnect you might expect from such different-sized drivers. The minimal crossover does just enough to shape the response where needed, while preserving the raw, engaging character of the drivers.


This measurement validates the listening impressions—a coherent, dynamic speaker that stays true to its vintage inspiration while performing with modern finesse.

Listening Impressions:

The final implementation of the Kronos exceeded my expectations. While I didn’t build these to be the ultimate reference monitor or the “end-all-be-all” speaker, the result is something that sounds exceptionally good—better than I had originally imagined.


The bass performance is particularly impressive, with deep, full extension that's further enhanced by room gain and proper placement. The SEAS woofer really shines here, delivering weight and authority without muddiness.


Tonally, the speaker holds up well across a wide variety of genres. So far, I've enjoyed everything from Rock, Jazz, Pop, Hip-Hop, EDM, to Classical, and the system has handled them all with confidence. The highs are clean without being harsh, mids are clear and natural, and the overall balance feels cohesive and engaging.


Even at very high listening levels, the speaker maintains its composure, with no sense of strain or collapse—perfect for those nights when you just want to crank things up and let loose.


I’ve also had a few friends over to hear them, and the reactions have been consistently surprised and impressed. There’s something satisfying about watching someone sit down with no expectations, and then light up the moment the music starts.

In Conclusion:
The Kronos has accomplished everything it was designed to do—and then some. It’s a speaker that brings together nostalgic inspiration, modern performance, and hands-on DIY fun in one cohesive package. I’m genuinely proud of how it turned out, and I know I’ll be enjoying these speakers for many years to come.


For those interested in diving deeper into the design—or even building a pair yourself—I’ve put together a comprehensive resource link below. This presentation has only scratched the surface, and the download includes detailed plans, crossover files, PCB layout, measurements, and more.


If you have any questions or run into issues, don’t hesitate to reach out. I’m always happy to help fellow builders in any way I can.


Thanks for taking the time to check out my project—I hope it inspires you to build something of your own.

LINK TO KRONOS BUILD PLANS: https://drive.google.com/drive/folders/1Kpa-w3JEGQmEdG6RKKRCQnM0pMenjgjl?usp=sharing

Hi All. New here.

I am trying to repair or replace (ideally) some Pioneer B20FU20-52D woofers for a home build from back in the late 90s.

Anyone have some for sale or know of a good replacement?

I saw that member "cT equals piD" had some for sale a while back, but I cannot message him directly.

I haven't found anything that sounds as good.

Thanks,
JP

I made this amplifier for test my home DIY speakers (two way TL).

D4 on component layout wrong polarity, in post #253 is corect componenet layout.

Pair of brand new Markaudio Alpair-10M Gold 6" Full Range Gen 3 (10.3) drivers for sale. Only taken out of boxes for inspection and pictures.

$206 shipped (US 48) PayPal

Does anyone have a component map for the phono boards in a 1000A? I need something that has the circuit boards printed out with designators on it for the parts. Also the 7 or 8 IO tabs on the bottom of the boards. What each leg is and where it goes. I could map it out the hard way but was hoping someone may have already done the hard work already. Also I am looking for a small circuit I can replace the stock circuit with. Preferably with improved performance.
Thanks for the help. It would be nice if Sansui had maps of the boards like most of the other brands do.

We've had previous discussions on this design but my issue remain unresolved. The design is largely cosmetic. The two 6" bass drivers are the same save for the dust caps.
My questions. If you disconnect one of the woofers are you left with a 2-way, passive radiator design?
Two: If you install a genuine 3-way crossover does the mid-range driver still serve duties as a passive radiator?

I would like the part numbers of blown resistors I think they are 4.7ohms but diodes D8 & D10. IC9 & IC14

It all started in the mid 1970s, when I worked as a mechanical designer for Scully Recording Instruments Co. in Bridgeport, Connecticut. They manufactured professional tape recorders and of course the Scully Lathe. They were located in the old Underwood Building on Bunnell Street. The Engineering department and the machine shop were upstairs and on the downstairs floor there was a demo room with a Scully 100, 2 inch, 24 track tape recorder and two JBL wooden horn speakers.

During my lunch break, when there were no customers, I would go down to the demo room, eat my sandwich, and listen to whatever was on the 2 inch tape on that particular day. The experience of listening to that professional sound equipment was overwhelming. It started me on the path of designing my geometrically perfect tone arm. My co-workers all had an interest in music in one way or another. Some played musical instruments and one was a part-time recording engineer. I played acoustic guitar and sang folk and country music.

Upon the advice of my co-workers I purchased a Thorens TD-124 turntable and a separate SME 3009/S2 improved tone arm. I started to purchase LPs and soon realized that a pivoting tone arm could not faithfully reproduce music the way it was recorded.

Being fascinated by all things mechanical, I set out to design my own pivoting tangentially tracking tone arm. Although my hat is off to the designers of tone arms like the Rabco and the Goldmund, I did not like the fact that those tone arms occupied so much space on a turntable. I also did not like the various pivoting tangential tone arms like the Garrand Zero 100 because they still skated and had tracking errors. Being a perfectionist, I could not understand why all the talented tone arm designers would stop short of zero tracking error and zero skating force designs.

This thread does not concern air-bearing and Souther style tone arms which are mostly perfect.

I always liked the classical appearance of pivoting tone arms, so I concentrated on them. I designed, built and patented my first tone arm in the early 1980s, and I would have continued if it were not for the fact that CDs came on the market. It wasn’t until 2009 that I found out that vinyl LPs had made a come-back. By this time, however, I owned a CAD program, had built a shop and purchased an almost new Bridgeport vertical milling machine.

By 2010 I had redesigned my original 1980s tone arm by moving its tracks and the carriage into the base underneath the tone arm. It required an active servo and was featured in a thread on the DIY website. In 2012 I improved the tone arm by inventing the “FLOATING HEAD-SHELL” which is shown as the third item in the group picture. Like the 2010 tone arm, it also required an active servo. Not knowing electronic design, I listened to LPs without the necessary servo by nudging the tone arm’s carriage along its track every 30 seconds or so. That became possible, because I separated the head-shell from the tone arm proper. Not knowing anyone who could design the servo circuitry for me, I kept making mechanical improvements until in 2015 I invented the “OFFSET HEAD-SHELL CRADLE”.

Then in 2016 I changed my design from a carriage rolling on a track to a swing arm to support the tone arm. Of course many inventors before me discovered that a swinging support arm is far superior to a rolling carriage. Then, early in 2017 a kind gentleman whom I met on the internet, designed the servo circuitry for me. I transferred that circuit to a printed circuit board and showed it to the public at the Rocky Mountain Audio Fest (RMAF) in October 2017, in Denver, Colorado. The transition to the swing arm reduced friction to the point where the tone arm started to float across the LP purely from the drag force between the LP and the stylus. The servo has become a “passive” servo and only controls the variations in the drag force. Some of the servo components were visible when looking down on the tone arm, which I did not like, and in late 2017 I moved those components to the underside of what I call the tone arm shelf. That way the tone arm would retain its classic appearance and it would make it harder for intellectual property thieves to steal my invention. That being said, anyone who wants to build a copy of my tone arm is free to do so, as long as it’s not for sale to others.

My original 2017 servo’s printed circuit board (PCB) utilized “through-hole” components. In 2018 I redesigned the PCB to utilize “surface mount devices”.

To summarize, I have invented a pivoting, tangentially tracking tone arm with a “FLOATING HEAD-SHELL” carried by an “OFFSET TONE ARM CRADLE”. Please note, that the HEAD-SHELL and CRADLE are NOT offset to reduce tracking error, as in a conventional pivoting tone arm. The offset cradle serves a new and different purpose.

I have a complete set of 3D solid model CAD files and paper drawings for my tone arm. I also have a number of simple but precise aluminum fixtures that I have made.

Now, after several years of machining, testing and experimenting, I am finally able to listen to my favorite music played back with a tone arm of my own design. That experience cannot be described and those of you who have designed and built your own audio equipment know what I am talking about. I have kept my modest collection of 250 LPs, which I purchased in the 1970s and 1980s in almost new condition and recently, a lady friend of mine gave me around 35 boxed sets of LPs that had belonged to her deceased son. There is enough music there to last for the rest of my life.

I hope that the members of the DIY website will forgive me for not making public all the design features of my tone arm, because I want to make it difficult for the copy-cats to profit from my invention.


And, last but not least, I would like to find a manufacturer to make and sell my tone arm.



Please watch for 14 photographs in my next post. I promise, you will be amazed.


Sincerely,


Ralf

HI!

I'm working on a Marantz PM6002 and I wanted to adjust the DC offset and idle current as a last step.
I'm a little confused after I checking it in the service manual.
Should I connect dummy load to the outputs during dc adjustment?
What voltage should I set if the manual says +/- 50mV? Isn't it a bit high?
The idle current adjustment is clear, it is the same as a lot of other PM models.

I'm retired from a career in sales and marketing audio. The last 30 years have been in the high end world. I still have my ears and continued to be amazed how everything affects the sound.

I've got Carver TFM-15, TFM-25 and TFM-35 amps that I use for a three way actively amplified speaker consisting of:

Altec 811B horns
Eminence Delta pro12A for midbass
Dayton Audio 12" subs

I currently use a DBX 234XS crossover which works fine except there is solid state hiss heard in the horns due to the TFM-15 not having any markings on the front panel for the input level controls nor does it have pots with detents. So there's no easy way to ensure the controls are set the same way every time the system gets used to DJ with.

I would prefer an analog crossover, but if there's a DSP crossover that is good enough for actual HI-FI use I'd be interested in that as well. The crossover also needs to be low noise as well given the Altec horns are quite efficient.

By popular demand, here is a new thread devoted to PETTaLS flat panel speaker simulation software, developed by Dr. David Anderson. Flat panel speakers may also be referred to as bending wave speakers, or DML speakers.
Let's use this thread to discuss topics specific to the use of and improvement of this great new tool. Topics could include, but are not limited to:

• new release announcements
• questions about how to use it
• features you'd like to see
• possible bugs
• interpretation of results
• other....

The free version of the software is available here:

PETTaLSFree

Some videos about the software are here:

PETTaLS Videos

Eric

Clearing out some bits and seeing if there is any interest


TWTMC-PPG-XO-22/24 MHz
22. 5792 MHz & 24. 576 MHz Pierce pico gate oscillators pair
€35

8x DIR9001 SPDIF Receiver chips
€15

17x OPA861 Transconductance Amp chips
€18


Triad Magnetics VPT12-8330
115Vx2 to 2x6V 100VA Toroid
Wires have been cut shorter, no mounting hardware.
€25

Triad Magnetics VPT12-23800
115Vx2 to 2x6V 250VA Toroid
Wires have been cut shorter, no mounting hardware.
€55

Triad Magnetics VPS24-5400
115Vx2 to 2x12V 130VA EI core
€25

Noratel TA250/18
115Vx2 to 2x18V 125VA Toroid
Wires have been cut shorter, no mounting hardware.
€40

Hello all,

Most that know guitar amps know that the JC-120 is THE BEST CLEAN AMP EVER - and the best Solid State Guitar amp in existence. These amps are found in all types of music - Jazz, rock and roll, metal, etc (Police - Andy Sommers, Metalica, etc)

Anyway, I downloaded the schematic (the version with 2SK117 not the later opamp version) and had a PCB fabbed with the help of a fellow DIYAudio member (Thanks Craigtone!!)

So the preamp has all the goodies including a quad of 2SK170 instead of the 2SK-117 (a deluxe version?) and behind it is a LM3886 - standard fab of Brian Bell's gainclone amp. Preamp has volume, bass, mids, treble and a Hi Treble switch. With LM3886. it's roughly 45 wpc. No reverb, chorus, etc, just the preamp / amp section. The rest you can do with pedals.

After building the amp/preamp, I bought a real Roland JC-120 Guitar amp, and surprisingly sounds very close. Bandmates were impressed!

Selling as I built another in a nicer case and it has a 200 watt/channel ICEPower 200ASC behind the JC-120 preamp.

Amp $150 + ship

Also have a few PCBs if anyone wants one - free you pay ship and you make a donation to DIYAudio site would be great.

Pics on the way...

Hello everyone.

Following the realization of several people of a class A amplifier (USSA-5 of Fab), I decided to draw a PCB dedicated especially to this one but that can be suitable for any other amplifier.
I wanted to do something fairly universal and practical and I told myself that this PCB might interest more people.

Features:

Size: 160mm x 100mm.
Possibility to put four capacitors up to diameter 40mm.
Possibility to put diodes (to220) soft or high recovery (capacitors provided).
Capacitors in parallel on the inputs of the diode bridges.
Possibility of putting an 'RC snubber' on the inputs of the diode bridges.
Possible resistances between capacitors from 5W to 10W.
'Bleeder' resistors from 3W to 5W

The latest version brings the possibility to put 5-legged capacitors and TO247 box diodes.


Update: Schematic:




Silkscreen:

This thread is intended to discuss the preparation and construction phase of building an F5 Turbo. A thread already exists for the circuit boards, so I'm guessing we will see a lot of activity here!

Looking for someone in the US, ideally the Pacific NW, who could build me a slightly modified F2 amp at a reasonable price
Thanks

Dear Antonio, Dear Nikos, and all others,

Thanks for your feedback, sorry for not answering faster but I have been quite busy recently... I am please to see that everybody received the PCB and like it, I am sure you will also like the sound, I am still trying to understand how to use a sound card to make some audio measurement, but as I say I don't have enough time now 😡

I have received several demand for more PCB's, even one person ask me if I could make a group buy but I have never done that and I don't know how to do that ? However, I could perhaps ask the PCB shop (EuroCircuits) to make more boards if there is enough interest. You will have an idea how the PCB look in the attached manufacturer file. If you are interested just send me a PM and I will see how many pieces could be built, for information the cost of the PCB for the previous batch of 10 pieces was 20 € per channel, 40 € for a stereo amplifier. Don't worry if you didn't get a quick feedback, I am not always on line, I do that for fun and I am please to help others as I have been supported in my project, but it take a lot of time 🙂

Best regards,

Marc

Hey DIYAudio community,

I'm excited to introduce Valvalyzer—a dream come true for anyone passionate about vacuum tube circuit simulation. If you’ve been searching for a tool that lets you dive deep into tube circuit behavior without the complexities or limitations of SPICE, look no further.

Valvalyzer brings together classic tube-era theory and cutting-edge computation in one free, interactive package. It lets you visualize, tweak, and understand every nuance of your circuits and transformer designs with precision and real-time feedback. Whether you’re a seasoned veteran or just starting out on your DIYAudio journey, Valvalyzer is designed to empower you to innovate, experiment, and truly make your mark.

Check it out, download it, and let’s revolutionize tube circuit simulation together. I’d love to hear your thoughts and see what you create!

— Jim Reese, AmpCad.com

Hi guys I just picked up a Starkit 12-22a tube tester and it needs a meter , does anyone know of a company that sell something that may work . (500au ) it's a real nice tube tester and would hate to scrap it for a simple meter .I tried using it with a volt meter attached to the meter outputs and it seems to be working .. thanks for any help .. cheers Roger

This weekend I found termite droppings on the floor underneath my mid/hi speaker box. I thought I got rid of the termites when I disposed of my old TL sub woofer but apparently they migrated to the mid/hi enclosures.
The enclosures are constructed of Okoume plywood. This plywood is not water resistant. I can wet it, but not for too long a time. These enclosures are simple small bass reflex boxes of about 30x30x15 cm. Easy to replicate with water resistant plywood. But not as nice to see.
The new TLs I sprayed with "Ortho Home Defense Termite & Destructive Bug Killer" before assembly. I have no signs of termites yet, but that doesn't guarantee they are not infested.
I am really worried about the termites migrating to my new TL subs which are much larger and harder to rebuild. So preferable I treat both the small enclosures and the TLs equally. The first first to expunge, the second to prevent.
Any ideas of how to treat for termites? Since the speakers are in a dry room, part of the time air conditioned, no moisture, I assume these are dry termites. I never see a sign of the insects or wings. Only excrements. There are no environmental or import restrictions on any chemicals. As long as I can purchase from Amazon.

Hello all, having trouble finding this information. I recently recapped my HK 12. I am struggling to find the correct bias settings for it? I see the test points, but... Anyone point me in the right direction? TY!

I'm in search of a decent 8" midbass driver. Needs to do mid-90s dB/2.83v and handle the 300 - 900 hz range with ease, preferably 4 ohm impedance.

The main issue I'm running into looking for a suitable driver is sufficient xmax along with efficiency. The driver will need to handle some decent power without turning into mush with loud transients. Obviously it will need to be some sort of pro audio driver given the application. Low distortion is a must.

Drivers like the Audax PR170MO don't have enough xmax to play louder without using steeper HP filter slopes. Levels I expect are 110 dB peaks in the specified range.

My other favorite B&C 8NDL51 isn't quite efficient enough and isn't available in 4 ohms. The 8PS21 has the same issue.

The 8PE21 is efficient enough as an 8 ohm driver, but not enough xmax to deal with a 300 hz 2nd order HP at higher output levels.

I've toyed around with the idea of using 2 drivers, but this will result in weird vertical dispersion issues.

Any suggestions?

Hello!

I'm going to pick up some Acoustat M3s (I think they are M3s, not 100% sure of the model) from someone's garage tomorrow. Don't know much about the condition except I was told they work. Looking forward to checking them out. I've always wanted to play with some electrocstatics. Do folks think these are a good speaker, and what do I need to know about them?

How should they be transported? I was planning to remove the assembly from the back and stack them flat on a piece of plywood.

I am planning to power them from a McIntosh MC2105, does this seem like a good choice? It has a 4 ohm output stage.

Thanks for any advice!

I just acquired an amplifier with two bad output transistors. They are no longer available. In fact, none of the suitable substitutes are available either. But I found one that seems to be pretty close. However, they differ substantially in something called the "current gain bandwidth product" which is 4Mhz on the replacement unit and 30Mhz on the original part. Everything else is pretty good. So what is this spec? And what does it mean, exactly?

Hiya,
Been posting some pictures here and there of a new project I have started on, might as well share the whole thing. The idea started in 2018 for a regular amp (speakers), but life happened and I lost track of audio once more. The good thing is that I already have some parts that I can re-use, so in today's thinking "they are free".

Goal:

• Headphone amplifier, 35 ohms
• Tube, single-ended,1000-1500mW of raw power power
• Daily beater, so no rare tubes, nothing end-game, just good music and a cool looking piece of kit
• Must fit on desk and desk must not collapse

Tubes:

• 4P1L
• 2P29L or 6E6P, might also look at other wee tubes like 6Z49, 6C4S, 5842 etc

As I want to tinker with the driver tube a bit, the power supplies will be setup to be universal for a 250V output tube and a 200V driver, current for each tube can be up to 50mA with headroom left.

4P1L will run at 225V/30mA/-19V initially (245V/30mA B+)
6E6P will run at 200V/30mA/-3.4V, 2P29L will be 6mA/-20V, so we have 30mA/-20V as worst cases for the PSU (225V/30mA B+)

As I am betting on the 2P29L, the rest of the info will focus on this combination so as not to have two projects in one.

Supply Chassis:

• Separate chassis for raw DC supplies to conform to the "must fit on desk" rule
• PCBs
• B+ will be SiC diodes, eChoke and MKP caps
• Filaments with SiC diodes and FW/KW caps

Signal Chassis:

• Filter for DH filaments, then Coleman regulator (current source) for DHTs
• LDO voltage regulator for IHT
• Passive B+ filter with RCRC to tune for both stages

Iron:

• 2x SE OPT 10K/50mA
• 2x Lundahl LL2763AM-40mA interstage
• 2x Toroid 250-210-0-210-250V/330mA, 12V/4A, 12V/4A

signal path



eTracer loadline on one of the 4P1L I have tested. 1.2W max with 10K.



Step 1: Concept
Step 2: Design PCBs for test setup
Step 3: Test
Step 4: Build chassis and integrated PCBs

Feel free to use this thread to post your DIY efforts.

From a thread I've been following, it appears there may be interest in discussing all things whisky (or whiskey for American and Irish variations). What's your favourite, how do you take it, where and when, why even? Excursions into other liquors are tolerated.

In theory and in practice, if you put multiple drivers together as in a line array, you are increasing the surface area of the cones. That in itself should be enough to push more air as if one were using a singe larger driver. However, according to one speaker designg program, this configuration does not afford any lower frequencies as if it was a single large driver.
So, could some one tell me why this would be so?
Thanks in advance.

As title sez - one name, two preamps. Major thingie is AVC Volume attenuation and, sheer luck involved, some free (magnetic) voltage gain.

Reason for 2025 presentation - to show present state (hopefully no further changes ), while there are two preceding threads where you can refresh memory.

Threads:



There is also Papa's tongue-in-cheak thread, I'll say no more, nudgenudge, say no more


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Iron Pumpkin SE, logically, being for single ended signal arrangement, so 5 RCA inputs, and one RCA output; I'm usually mounting doubled RCA outputs, wired simply in parallel.

Iron Pumpkin (no suffix), balanced signal configuration, any number of 5 inputs can be arranged as (permanently) SE/RCA, balanced output can be wired to one or two (parallel) XLRs, or one XLR and (parallel) RCA

2025 iteration, besides major physical change to Big Motherboard, is also having altered arrangement of Iron Turtle (AVC) module,e with (new) 28 steps arrangement.
Step 24 is 0db,
step 23 down to step 1 are each -2db,
step 25 to step 28 are each +2db.
So, ranging from -46db to +8db. Previous arrangement, with 24 steps and jumpers for (permanent) gain set stays as solution for kit/finished preamp with physical/rotary switches controls.

And, yes, now there is a choice between Metglas and Finemet cores; what's the difference between two - pretty much the same as between Cinemag normal nickel and CInemag high nickel - normal isn't much worse than high nor high is much better than normal........ but when you shoot, you usually shoot for better sleep

Dazzling, Shiny and Overwhelming characteristics speech: Fully dual mono (custom made 20VA Donut for audio circuitry is having separate secondaries for channels; custom made 10VA Donut feeding all things Logic and switching), ultragigamega shunt regs, OhYeah! Toshiba For Audio JFets serving in buffers, precious Fujitsu relays for everything what's switched, volume attenuation as explained above, yadayada.......

Button on front, fiddle left-right to set volume, push for incremental cycle through inputs 1 to 5.

Fancyschmanzy remote having same functions, plus mute/unmute buttons.

3.5'' TFT as Eye Candy, Tesla writing for ZML Greetings, then Led Zepp font for functional screen.

In the fall of 2023 my family relocated to North Western Connecticut which is an area that is a bit more rural than we had experienced previously.

One of the daily joys of living in this new area has been the almost daily sitings of wildlife…everything seemingly wanders into our yard when we least expect it…deer, bears, coyotes, hawks, eagles.

One of our favorite almost daily sitings is the Fantastic Mr. Fox who has set up residence on the edge of our property the past two years with Mrs. Fox and produced a brood of 4 pups both years.

The pups usually start venturing out some time in April. Most likely mom is trying to give them some practice at hunting mice for themselves. They are seen playing in and around the pool and rocky bank towards the bottom of our property.

I’m lousy on the draw with my phone camera. I’m sure some of you guys are much better.

Post a pic of some of your furry wild friends that you caught a glimpse of.

Hi all! New member here.

I'm an electronic beginner, and as a first analog project (until now I played with arduino and similar) I wanted to make a simple chip amplifier with some controls.

I managed to find a TDA1557q and a TA7630P.

So, I breadboarded the TDA1557q sample circuit from the datasheet and the TA7630P sample circuit, also from datasheet (single power supply one).

The main problems are two:

1. When i plug my phone aux into the TA7630P circuit the output volume is really low, instead, when i plug the phone directly in the amplifier, is much higher. I read something about audio buffer, it can be that?

2. When i connect the TA7630P circuit with the TDA1557q one I hear only noises and I am able to hear some music (low volume) only by placing a 470ohm resistor to ground before the input cap

I've been working on this two chip since two weeks, I'm running out of ideas. 🙁

Any help would be appreciated, thanks.
I also uploaded some photos.

Esse circuito de amplificador super simétrico aplica boas técnicas discutidas aqui no forum.
Essa topologia de circuito é a mesma aplicada na tese de mestrado do Professor Leach.
McIntoch, Rotel e outros aplicam a mesma topologia de circuito em seus amplificadores de estado sólido.
Agradeço por comentários relacionados com melhorias nesse amplificador. Corrente de bias é um parametro que pode ser escolhido pelo montador.
(Comentários em ingles pelas regras do forum).


This amplifier idea uses good technical ideas discussed here.
The circuit toppology is the same used by Leach in this master tesis.
McIntoch, Rotel and others makes uses the same circuito topologies in his solid state amplifiers.
I appreciate comments concerning improvements of this amplifier. Bias current is a parameter each one can choose and it wil not improve this amplifier as it is a option of the amplifier maker.
Regards

Hi, I am hoping someone can help me with this amp, I have spent a lot of time looking for the problem.
-I started this project and when I needed to buy the mosfot, (Hitachi 2SJ50, 2SK135). I found they were off sale. Then I found that Profusion sold replacement models, (ECF10N20 and ECF10P20), I bought them and mounted them but at the output it had a noise as if it was AC. And that is that it was oscillating. The oscilloscope shows a frequency of 8-9Mhz, with nothing at the input.
-I have been reading in this forum that these mosfets have been mounted as Hitachi and other replacements, and I have seen that the schematic may need some modification, like adding some capacitor or changing some resistor. But my knowledge does not reach this.
- With help, I changed the capacitors C6 and C7, from 33pf to 180pf, but it was not enough, the AC noise at the output is attenuated, but it is still oscillating and it is impossible to regulate the Offset.
-This is why I am asking if someone can help me to get it to work with these Exicon mosfets, because with Hitachi mosfets this schematic work well.


Also, I am looking on this website for alternatives in case I don't find a solution to my project, and use part of the main components, such as Mosfets and power supply.Only I found this proyect with ECF10N20 & 10P20 mosfet mounted. https://www.diyaudio.com/community/threads/elektor-axl-v2-with-lateral-mosfets.332535/
But I don't know if this project could work with double pair of mosfet and power supply could be 50V.

Thank you so much.

Hello together! I registered to learn and ask the kind members of this forum as my brother and I want to take further steps down the rabbit hole to develop our own speakers.

Also, I am a long term friend of restoring old speakers, mainly Magnats from the 90s.

Last but not least, I found an interesting Amp sales offer in your sub-forum and would really like to reach out to the seller🙂

Acoustic Horn Design – The Easy Way (Ath tool)

This is an associated thread for a waveguide generator called Ath (Advanced Transition Horn), version 4.
Ath is a piece of software for designing waveguides and horns. At the same time it makes it possible to easily simulate their acoustic behaviour by means of FEA (BEM) via ABEC/AKABAK tool.

The current Ath release is available at https://at-horns.eu





Thread milestones (last edited 26.12.2020, no longer maintained):

#233 Birth of the OS-SE formula
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#375 Measuring driver's exit wavefront
Acoustic Horn Design – The Easy Way (Ath4)

#666 Some of the practical verifications:
Acoustic Horn Design – The Easy Way (Ath4)

#844 Ath 4.4.1 - Introducing superformula
Acoustic Horn Design – The Easy Way (Ath4)

#922 JBL M2 "How-to"
Acoustic Horn Design – The Easy Way (Ath4)

#933 JBL M2 - Ath clone
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1003 Comparison of an OS waveguide and a flat piston
Acoustic Horn Design – The Easy Way (Ath4)

#1117 Ath 4.4.3 released (Fusion 360 import)
Acoustic Horn Design – The Easy Way (Ath4)

#1533 Ath 4.5.0 released (scripts not backward compatible)
Acoustic Horn Design – The Easy Way (Ath4)

#1602 General phase-plug discussion
Acoustic Horn Design – The Easy Way (Ath4)

#2389 Joining profiles of different curvatures
Acoustic Horn Design – The Easy Way (Ath4)

#2494 Tritona Waveguide
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)


Spherical-wave phase plug

#1706 Initial ideas
Acoustic Horn Design – The Easy Way (Ath4)

#1824 Kessito's input
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1892 Compression cavity modal analysis
Acoustic Horn Design – The Easy Way (Ath4)

#2016 Diaphragm suspension analysis
Acoustic Horn Design – The Easy Way (Ath4)


Free standing waveguides

#2600
Acoustic Horn Design – The Easy Way (Ath4)

#2936 Rolling back the profile
Acoustic Horn Design – The Easy Way (Ath4)

#3390 Employing axisymmetric BEM (finally)
Acoustic Horn Design – The Easy Way (Ath4)

#3427 Rollback added
Acoustic Horn Design – The Easy Way (Ath4)

#3532 Source amplitude shading
Acoustic Horn Design – The Easy Way (Ath4)

#3549 OS-SE formula extended: k
Acoustic Horn Design – The Easy Way (Ath4)

#3664 Effect of an enclosure and other parameters
Acoustic Horn Design – The Easy Way (Ath4)

#3822 Compression driver throat plug
Acoustic Horn Design – The Easy Way (Ath4)

#4186 Preferred in-room response and DI target (discussion)
Acoustic Horn Design – The Easy Way (Ath4)

#4503 Incorporating compression driver model
Acoustic Horn Design – The Easy Way (Ath4)

I am working on this Bogen Challenger RC412 (tube receiver from about 1960) that has a few problems, one of which is a blown line choke at the AC in. According to the schematic it is 1.9uH, I have not been able to find a replacement.

Any ideas?

See attached pics.

hello,

it's Andrea here, long time lurker and appreciating a lot this community. this is my first post, just registered to signal a China board i've not seen described here.

of course, i've not any economic interest in the vendor. i've just ordered one sample to check the quality because it looks like a compelling price! 🙂 i don't' know what to expect..

i tried to find schematic info and demo project but nothing to be seen.. have you ever heard about this stuff?

bests

andrea

We'll be improving the enhanced thread print function (a donation only feature) in the future.

To be sure we create a tool that does exactly what it needs to, we'd like to know how YOU use this feature currently.

Do you actually print?
Do you save it for reference and look at the file offline later?
What's important to be in there, and what's important to not be in there (eg: text or flourish that serves no information purpose but would consume ink if printed)?
Options for turning images on or off?

Right now we're not sure what's important to you. Please let us know 🙂

A strange occurrence for my TSE 11, I just finished the build after approx 8 hours or so, the source plays inside the chassis as if it has a speaker, it happens every time it is turned on, it also plays normally through speakers w/o any noise whatsoever, it is affected by the volume controls, which are Goldpoint, if they are at 50% then I cannot hear the inside speaker. Has anyone experienced this?

After listening tests of my pre standard II JFET preamplifer, and upon requests of the builders, I have decided to design a new version of the Dipre 2 preamplifier, Dispre 2 - JFET.

The main difference is that Dispre 2 – JFET has Toshiba 2SK170/2SJ74 devices in the input stage, not the bipolar transistors that were used in the Dispre 2 V4. This modification resulted in a design of a new PCB board, as it was impossible to simply replace BJTs by JFETs, circuit modification of the input stage had to be made. At the same time, I added two resistors to enable setting of the output stage idle current. These resistors allow, in case of high technology spread of output devices, to tune output stage idle current.

Dispre 2 – JFET can be also used as a headphone amplifier, without any components changes needed.

Dispre 2 – JFET has complementary differential circuit topology with self biased JFET input stage (this topology was introduced by John Curl). This maximizes linearity of the input stage and distortion suppression does not rely only on an overall negative feedback. To remove output DC voltage component, DC servo is used.

Output stage idle current is set at 40mA, and it works in a class A up to 8V into 100 ohm load. For standard link load 600 ohm and higher, the output stage works in a class A for the whole range of output voltage up to clipping.

Dispre2 - JFET has wide bandwidth and high slew rate again, similarly as Dispre 2 V4.

Regarding PCBs, please visit a thread here:

https://www.diyaudio.com/forums/vendors-bazaar/166049-dispre-ii-pcbs-available.html

or check my webpage:

https://pmacura.cz/dispre2-jfet_en.htm

This is a design I've had in use for rather a long time. It started life as a design exercise to see if I could do a more space-efficient board for my original AEM6000 based amps, as I wanted something that would fit on a 50mm high heatsink. Along the way it changed a little from Tilbrook's original in topology, and rather a lot in component choice. It has better performance than my original design, both through a better tighter layout and also through the use of faster transistors.

I've built a bunch of these, using both Renesas and Exicon lateral MOSFETs, and subjected them to all manner of abuse. I had one fail, due to a leaky mica compensation capacitor (see noiseUnit speaker thread), but apart from that they've been rock-solid.

Lots of component substitution is reasonable. I like to use MELF resistors, but that's mostly just bloody-mindedness. An exception is the feedback divider. No, it won't work with vertical MOSFETs.

I have checked just now, and every single component is currently (December 2020) available.

The design is free for use for non-commercial purposes.

In the design folder I have placed:


Google drive containing design files.

Anyone out there with any old Pink Triangle kit (DaCapo, Ordinal, Cordinal, Litaural). Re-cap it asap!
One of my customers just sent me a DaCapo which had failed. Worst case of capacitor rot I've ever seen!

Can someone tell me why it is when I switch on power on my base 1800 series vi professional amplifier the peak / protect light will and the power light will come on for about 3 seconds and then cut completely off.... The amp is in a shutdown state

Hey team,

If anyone can help me out with this, it would be greatly appreciated!

Equipment:

• Video camera: Sony Handycam FDR AX-40
• Audio source: Any audio source with 3.5 mm cable (aux) (3-pole), but it is mostly mic signal from an audio interface

Scenario 1: (Recording video with Power Adapter)
- As soon as audio cable is inserted into the mic-in jack there is a continuous noise on the audio track. Even when there is no other device connected to the other end of the 3.5 mm cable.
Scenario 2: (Recording video without Power Adapter)
- There is hardly any noise, if there is any, it is probably RF and other interference from camera's normal operation.

Attached is a very basic image file to help understand the device setup.
Attached is also a sample of audio with and without noise. (initially, with adapter, then without adapter). Warning: Headphone users and users of loud speakers may please reduce the volume before opening audio file. Zip file contains M4A and MP3 formats. audio length: 13 seconds.

thank You for reading about a problem that i am facing.

Hi all,
I was looking at the new UCG28826 controller yesterday.

I am wondering if it is possible to put a ~1:7ishflyback transformer at the end of this to step it up from ~190ish to 1kv.

At 65w with 140w transient peak power it would certainly be good on the primary side

With 1:7 does that step down va as the voltage steps up?

Also I would require a hefty optocoupler, but maybe use a voltage divided and do the math that way?

Ti is cool I have to say

24V dc to 300V dc capacitor charger with regulation (300V at 150mA at 78% efficiency): https://www.analog.com/media/en/technical-documentation/data-sheets/lt3751.pdf

So this not only can cope with managing inrush on a 2+mF 300V cap, it can also then regulate current output too. User configurable max charging limit too..

Seems it may be of interest to tube users.. now if only there was a larger regulated 500mA-1A version.

There’s also a coilcraft transformer specifically for this..

Hello, who collected the Apex a17? assembled this amplifier, there is self-excitation how to eliminate it?

Thought it best to consolidate the inquiries re the Elsinore Project into a single thread, so issues can be dealt here.

We are currently as of June 7th, 2024, up to page 298, click on this link.


March 1st, 2023. Elsinore Mk6 "ULD" Version. These are very expensive Purifi Audio "ULD" drivers.


There are three variations of the Elsinores:

The "MFC" uses arguably one of the best polycone drivers. Very high sensitivity.

The "NBAC" is the latest variation, uses the same driver but with black anodised aluminium cones. The "NBAC" requires a more powerful amplifier, roughly about double, but is still incredibly amplifier friendly, as all Elsinores are.

The "ULD" is the premium Elsinores, using extreme Purifi Audio drivers that are of the highest quality available. As high sensitivity as the "MFC" and around 20% more efficient. One manufacturer and friend has said that to manufacturer and sell the "ULD" would mean around $50.000 retail.

Nobody manufacturer make a speaker that measures anything like below:


This speaker looks like a resistor to the amplifier. As close as possible, above 25 Hertz, the amplifier will draw the same current at all frequencies. This makes the amplifier's output impedance largely cancelled out. These speaker can be driven by all amplifiers with an impedance from zero to infinity. They are also suitable for so-called current-drive which is becoming more common and has an increasing following. All Elsinore variations are suitable with amplifiers like Nelson Pass First Watt amplifier. This is the most amplifier friend speaker designer ever! Until somebody starts using this approach to speaker design.