Hi everyone,


I'm working on a Sansui AU-D9 that had several issues, most of which I've resolved:

• Replaced leaky capacitors
• Removed the infamous "black flags"
• Replaced the burnt output transistors
• Replaced the drivers
• Also replaced the distortion correction stage transistors

Here's what I’ve already checked:

• Verified all flame resistance
• Checked voltages across preamp, differential stage, and power stage
• Found inconsistent voltages on two transistors (I can provide details)
• The protection relay engages normally
• All solder joints and PCB traces appear fine

The current issue is that the output transistors do not amplify.


Using an oscilloscope, I can confirm that the signal reaches the base of the output transistors, but it does not get amplified. At the output, I can only see the signal from the distortion correction stage, as if the power transistors are not conducting at all.


Bias is set according to the service manual, and the power supply voltages are correct.


Has anyone experienced a similar issue with this model? Or any suggestions on what to check next?
I'm happy to share measurements, circuit photos, or relevant parts of the schematic if that helps.


Thanks in advance for any help!

Hello everyone, can anyone help me with the DP48X driver and FIR48 firmware? I also don't know if my board is version 1.0 or 2.0. I hope everyone can help me. Thanks for reading.

I have a new build.

Schematic attached EL34, 12AX7 (preamp), 12AT7 (inverter)

There is a massive hum that changes pitch and loudness with the tone stack.

Trebble off, there is no hum, defiantly in signal path

With both preamp tubes out there is no hum.

With the 2nd tube in there is a little bit but not much at all.

When I put in the first tube the hum is there, and it is huge.

Master is up all the way, gain is off. ( first stage not the issue)

This has to be between the 2nd and 3rd stage.

My thinking is bad component or ground loop issue. Everything is new.

Currently R40 and D4 have been removed.
C22, C23, C13 are not installed yet

There is a grounding buss bar for the preamp section, the ground icons are where they connect to the buss, and I have noted how I have them grouped before connecting to the buss.



I have resoldered everything.

Not sure if this matters but C18 makes noise through speaker when tapped.

I changed that component, no change.

Amp does play

Swapped preamp tubes around but no effect.

Hi everyone,

My name is Alex and I currently reside in Belgium. Started doing electronics projects while I was a teenager in Greece and when I have some spare time I like to play around primarily with audio projects, repair electronics.

I have currently 2 amps that I fully completed and are functional on my workbench:

• A dual lm3886 built around 2012 (still need to add speaker protection though... I will eventually kill my speakers 🙂 )
• A K502 kit with a quad of 11BM8 tubes (triode + pentode) that I built buil back in 2008 while I was in Canada

Hey everyone, I just finished my first diy project which consisted of the Gabster Td1 V3.4 dac and Ian Canada's boards. Since I only needed it for usb and optical use a raspberry pi was not included in the build. Building the Td1 was fun and a little challenging; I would strongly urge any new builder to use fine low melting point solder, a small tipped soldering iron and flux on everything being soldered. The key for first timers is to follow Gabster's videos on his site when assembling. As for connecting Ian Canada's component boards it is critical to look up each board on his site and read the instruction manual for each product there. My interest in this project started when I stumbled on a Gabster video on YouTube. I thought Gaby was sincere in presenting his dac. As it turns out all of his claims about Gabster Td1 are true; it produces a huge sound (soundstage) with remarkable imaging that is almost addicting. I find myself listening music now way into the night. I use the Gabster dac in conjunction with my NSMT model 100 speakers which are known for their accurate sound and superb imaging.

HI!

my name is Vincent and I own and run a studio/record label in a small village in Germany called binary pleasures.
I was interested in sounds and textures from a very young age and also love repairing and modifying electronics and equipment I use to work on music.
Now I would love to slowly step into the DIY speaker game but I am very overwhelmed by all the information both in the physical (acoustical) and electronic domain.

I am working on a little project to help me see what I am listening to in a fun way. The project uses a teensy 4.0 with a spdif in from a topping dac. The details of how I get spdif from the topping to both the teensy and hypex plate amps is a WIP. One route uses the WM8805 SPDIF chip and the other isolates the spdif to split it. The galvanic isolation is the first thing for me to try.

My user interface is pretty solid so far. I just need to link my two halves of the project together: the UI and Visualizer.

Here is an early UI test:
Login to view embedded media
The VL53L8CX TOF sensor can use a 8x8 grid at 15hz or 4x4 at 60hz. The video is showing the 15hz version. The current UI just uses 4x4 because the responsiveness is preferred. One just needs to select 3/4 of the blocks that make a corner to activate.

The visualizer currently has these modes:

COLOR_A_HEIGHT, // Height-based rainbow (Default)
COLOR_B_GROUP, // Band group color
COLOR_C_RED_SHADE, // Band red shade
COLOR_D_LEVEL_COLOR,// Column color by level (Bar Graph style / 16-band BG Fill)
COLOR_E_PIXEL_LEVEL,// Pixel color by position/level- each pixel cycles through a series of colors as the level increase
COLOR_F_DELTA_COLOR // ** NEW: Bar color by rate of change ** the time between level changes generates different color bars along with showing the active level

I plan on adding a few more. Maybe for L/R levels with the proper timing and the ability to change the calibrated level.

All of the colors work on a 8X8 full display or 4X8 with two rows. So a 8 band or 16 band visualizer.

Here's a summary of the frequencies used by the 8-band and 16-band FFT configurations, assuming a 44.1 kHz sample rate:

### 8-Band Frequencies:
Band 0: 0 Hz - 86 Hz (bins 1-2)
Band 1: 86 Hz - 129 Hz (bins 2-3)
Band 2: 129 Hz - 258 Hz (bins 3-6)
Band 3: 258 Hz - 516 Hz (bins 6-12)
Band 4: 516 Hz - 1032 Hz (bins 12-24)
Band 5: 1032 Hz - 6027 Hz (bins 24-140)
Band 6: 6027 Hz - 10036 Hz (bins 140-233)
Band 7: 10036 Hz - 22050 Hz (bins 233-512)


### 16-Band Frequencies:
Band 0: 0 Hz - 129 Hz (bins 1-3)
Band 1: 129 Hz - 172 Hz (bins 3-4)
Band 2: 172 Hz - 215 Hz (bins 4-5)
Band 3: 215 Hz - 301 Hz (bins 5-7)
Band 4: 301 Hz - 430 Hz (bins 7-10)
Band 5: 430 Hz - 602 Hz (bins 10-14)
Band 6: 602 Hz - 860 Hz (bins 14-20)
Band 7: 860 Hz - 1204 Hz (bins 20-28)
Band 8: 1204 Hz - 1721 Hz (bins 28-40)
Band 9: 1721 Hz - 2409 Hz (bins 40-56)
Band 10: 2409 Hz - 3442 Hz (bins 56-80)
Band 11: 3442 Hz - 4819 Hz (bins 80-112)
Band 12: 4819 Hz - 6885 Hz (bins 112-160)
Band 13: 6885 Hz - 9638 Hz (bins 160-224)
Band 14: 9638 Hz - 13770 Hz (bins 224-320)
Band 15: 13770 Hz - 22050 Hz (bins 320-512)

The short of it is that I get 512 bins in 43hz jumps.

Next up is to merge my code up and add more to the UI.

I have several Ideas for custom designed 3D printed brackets to mount boards in power amp and preamp designs.
This is especially nice for PS boards mounted above transformers is my dual mono and quad mono power amps - 4u and 5u empty space at the top can be utilized

Bambu lab has a flame retardant filament.

Any thoughts are welcome, thank you!

Hello I have a JL AUDIO HD 750 that I'm trying to repair Maybe you could assist? Do you have a schematic you could send me ? The green light was flashing. I found 2 bad rectifiers and replaced them. The light was solid green and I got audio for a short time. There was some popping distortion...
It intermittently plays audio with a solid green light then switches to no audio with a flashing green light.

The caps and resistors and fets are testing good

How to DIY making a paper cone (or others) more stiff.

Here first example:

fast drying hairspray liquid





Never apply too much at once so the paper fibers do not become wet and weak and throw wrinkles!

Better less but several times applying

then if possible fast dry in the sun

http://www.diyaudio.com/forums/mult...coaxial-midrange-crossover-2.html#post5415661

So, now I have a pair of MR18 in my hands! My plan is to make a semiactive 3-way using it and SB29NRX woofers, floorstanding sealed box and minidsp PowerICE-125 amplifier-dsp boards.

Here are my first measurements of MR18 in a 7 liter closed box, baffle 19x28cm. We can see from nearfield measurements, that the peak at 5kHz is NOT exactly cone resonance, but more like a cavity resonance based on geometry. Look how nearfield off-axis measurement changes in normalized graph!


Looks like the tweeter shows directivity only in low treble and is exceptionally non-directive up to 10kHz. Crossing around 2,5 - 3,5kHz should be ok. Peak attenuation at 5kHz is perhaps not needed at all. Lower xo around 400Hz LR2 should be easy too.

Here some Edge simulations and a 3d sketch of the box. Top part of the baffle will be tilted and I will add diamond cuts to edges following the style of Avalon speakers. Box material will be MDF with birch veneer, tinted and waxed. These speakers will be a joint project with my older son.

Hi Thanks for reading I have a pair of 2-way b&w dm110 speakers, and a m&k active subwoofer

The amp I am using with the b&w is a topping pa5 II

I want to create a 2.1 system and make the b&w speakers reproduce everything over 200hz, and the subwoofer reproduce everything under 200hz

I’m thinking of removing the crossover from the b&w, and replacing it with a 100uf capacitor to act as a high pass filter. I’ll probably have to play around with the value of the 100uf cap to make it integrate well with the subwoofer

Q: Are big 100uf caps safe to use with amps on a long term basis, and would there be any resonance problems you can think of

Design Phase - 35Hz Tapped Horn w/ Compression Chamber (Hog Scoop + Inverted Driver)




This project has been inspired by all the love for Hog Scoops... And the fair share of hate they get as well.

This will bee my first attempt at an 18" horn subwoofer.
Proposed plan is based on the well known "Hog Scoop",
a tried and tested free design hosted over on the freespeakerplans.com forum.

https://www.freespeakerplans.com/?view=article&id=31:hog-scoop

Drawn up nearly 20 years ago, this well proven classic has stood the test of time and is a very
clever piece of speaker box design, still to this day.
Credit for this creation must go to Stipe Ercegovic, more commonly known a Staiper, a well respected member on the Speakerplans Scoop subforum for a long time,
but he disappearred from there several years ago and doesn't seem to frequent these places anymore.



The Hog Scoop, technically an F1 hybrid of sorts, the offspring of two genetically similar species,
living a life somewhere between a tapped horn and a traditional back loaded "scoop".
A rear loaded horn with the bonus of the driver shooting into the horn path, or a tapped horn enclosure
equipped with a compression chamber.... Call it what you will, this quarter wave resonator is well capable of
hitting the low bass notes and producing high SPL when equipped with the right hardware.



So, I would like to run inverted drivers in a slightly tweaked version of this enclosure, something similar to the image attached to the end of this post.
These are the M4.18 subwoofers, made by MM-Acoustics in Europe, a Macedonian outfit headed by Marjan Milosevic, a regular poster and long time member over on SP.

My god, they look absolutely amazing, so business like.
This is the look I am going for.... They are absolutely badass indeed.


Anyway..... enough airy introductions, and down to business then !!




Hog Scoop Hornresp input parameters






First things first, I decided it would bee prudent to simulate a hog scoop with a driver in it's normal orientation first..... Cone side out.
This was to bee my baseline sim, a benchmark to work from before l went tweaking the original design.

And staight away I ran into problems.


For a start, the speakerplans.com forum isn't very active these days..... And a huge amount of information from back when it was is just lost.

Many externally hosted images are not there any more, there are many dead links, hosted plans, you name it, gone !!!
It didn't make my research easy but I did what I could with what I had.

That said, there were many helpful and informative threads to bee found amongst all the bickericking and the politics in the Scoop subforum.




So, lets discuss what was available to find on the net first.... Multiple posts regarding the Hog Scoop hornresp input parameters were scattered around the web....
And just not consistent.
I was hoping to pull some numbers out of a post or a sketch somewhere but straight off the bat, numbers and posts were conflicting.

Unfortunately, I found more than one set of digits, which only infuriated and confused me even more.

Here are the most posted (and reposted) HR Hog Scoop numbers, I beleive they orignally came from Staiper, and these ones were the most common to bee found online,
copy and pasted in at least 4 different places, so I am inclined to stick with the guy who originally penned the Hog Scoop design. He did create it after all.



Stipe Hog Scoop

S1 = 750
Con = 112.8
S2 = 1062
Con = 42
S3 = 1770
Con = 51
S4 = 2544
Con = 47
S5 = 5700
Vrc = 0
Lrc = 0
Fr = 0
Tal = 0
Vtc = 49456
Atc = 86




Re-posted by bitzo,
https://forum.speakerplans.com/forum_posts.asp?TID=16974&PID=214119&title=database-simulation#214119

toastyghost,
https://forum.speakerplans.com/forum_posts.asp?TID=16974&PID=727583&title=database-simulation#727583

Bee,
https://forum.speakerplans.com/forum_posts.asp?TID=72607&PID=828911&title=hog-scoop-drivers#828911

and salzburgsound system



The next set of input data numbers to bee found were these ones you see below.....
--------->



S1 = 750
Par = 0.10
S2 = 750
Par = 200.90
S3 = 1700
Par = 61.00
S4 = 4740
Par = 12.10
S5 = 5700
Vrc = 0
Ap1 = 0
Lrc = 0
Lpt = 0
Vtc = 37060
Atc = 1453.10




Posted by Heathrow B Line
https://forum.speakerplans.com/foru...=901195&title=scoop-hr-reference-guide#901195

epa

Freddi





And one more, with newer and revised numbers, taken from a post by user "epa" from 2014.

S1 = 750
Par = 0.10
S2 = 750
Par = 187.90
S3 = 1700
Par = 52.00
S4 = 4740
Par = 12.10
S5 = 5700
Vrc = 0
Lrc = 0
Ap1 = 0
Lpt = 0
Vtc = 41091
Atc = 2210.00


Posted by epa




Other than these three sets of input parameters, I did find a few posts by Staiper himself, modeling the Hog Scoop as an exponential horn,
in quite a numerically sparce fashion I must add.... It would seem this stripped down form of modelling came from Rog Mogale himself.
i will link after the following
---------->





Staiper Exponential Hog

S1 = 750
S2 = 5700
L = 260 EXP
Vtc = 36000 (with driver)
Atc = 1000

https://forum.speakerplans.com/forum_posts.asp?TID=8887&PID=218876&title=hog-scoop#218876




Staiper Exponential Again....

S1 = 750
S2 = 5700
L = 257 EXP
Vtc = 37000
Atc = 9000

https://forum.speakerplans.com/forum_posts.asp?TID=8329&PID=77534&title=tapped-horn-design#77534



And finally....... An attempt at simming a Hog Scoop by the man, Rog Mogale himself.

S1 = 750
S2 = 5700
L = 240 EXP
Vtc = 35000
Atc = 890

https://forum.speakerplans.com/forum_posts.asp?TID=8329&PID=77097&title=tapped-horn-design#77097



And here is a good thread full of interesting tit bits where Rog discusses his exponential scoop modelling methods with others.
https://forum.speakerplans.com/forum_posts.asp?TID=8329&PID=77097&title=tapped-horn-design#77097

A must read for anyone into this line of work.






Annd..... Time to take stock.

All my research and reading paid off, but unfortunately I still feel I do not have any concrete numbers for a Hog Scoop simulation binge.

So, I took some time out and drew up a scaled plan of the Hog, just enough to play with.
it gave me a much more definite idea of the direction I asm going in, speaker boxes ofthen quite literally build themselves as the project goes on.
Solutions are often just so obvious when you have the material object taking shape before your eyes.

And measurements can bee taken from the plan and scaled up to something that resembles real world numbers.
(Drawing attached)
And just to bee sure, I am going to get my hands on one side panel first, (18mm sheet board 986 x 950mm) and draw it out @ a life size scale on the floor.





Drivers for this design


I currently have 2 B&C 18TBX100 (4 ohm) belonging to a friend to use for the first 2 boxes and am debating which drivers to buy for the rest.

Quite likely B&C as well, I like the power handling (1500w) and price of the 18SW1OO.
When given the option, I usually buy 4 ohm versions of any driver when I can.
They can often bee had for the same price as their 8ohm equivalents but sometimes not. Sometimes they are just more hassle to obtain but I do make an effort to
use 4 ohm drivers when ever I can.
I am also open to other brands, I do know I need a certain type of driver to do well in these boxes and if one particular driver turns out to bee
especially suited to the task it will surely bee strongly considered.




So far, everything is going well.... The only other uncertainty I have right now is the design of the rear chamber.
I am not sure exactly how it will end up but I am confident the design (and build) process will answer it's own questions if and when they arise.
More on that in detail later.

Okay, I think I have written enough for now.... Any advice and criticism is warmly welcomed.
Please feel free to join me on my journey of discovery and don't bee shy to interject or comment if need bee.

Connection cable wanted to connect meridan C 207 unit A to unit B . I am located in USA northern Virginia . If some one had this cable or know a place to purchase it , I will be very grateful for your help . Thanks . Ali

Any of these dope?
Used for audio?
Make offer on anything in thread, if you want.

Hello,

I recently picked up a pair of Monitor Audio r352 speakers of eBay, but they didn't come with any stands. I like the look of the stands that came with these back in the day (see the attached photo), but I can't find any information about them online. I reached out to a couple of eBay sellers who were selling the speakers with stands, but their either didn't reply, or couldn't help. I even reached out to Monitor Audio, who after a while got back to me to say they also had no information in the archive, nor did they have a pair in storage.



It's a long shot I know, but I don't suppose anyone on here has a pair of the stands and could supply me with the relevant measurements...?

If not, can anyone recommend some rules of thumb, around the size and thickness of both the base plate and column? The base of the speaker cabinets have captive nuts, so I guess the top plate size if pretty much self explanatory. The only other thing I really need is some for some guidance over the angle the speaker sits at.

Any construction tips for stands? Is it simply a case of screwing the column to both plates and calling it done? Or is there a better way of joining everything to help dissipate, or mitigate, vibrations coming up from the floor?

Any help would be much appreciated.

Interested in buying Sony VFET amp boards for N-CH version.

Thanks.

Hi All

Please help to identify the parts marked in the Ice Power 1000a module picture they are adjacent to the input connector. I have 2 modules one the parts have unfortunately come off and got lost in transit and one module with the parts populated. Most of the components are marked and identifiable, somehow the parts that went missing are not marked.

Below is the module with the parts missing in blue

Below is a picture of the module that is with all the components.



Thanks.

Hi friends

I know it is a bit off audio, but as the best of the best are here, I dare to ask:

Does anyone of you know a coating for brass that withstands water and cosmetic chemicals (like soap, shampoos, lotion, all that gooey stuff one finds in a western bathroom...), available in switzerland/europe? If it is not glossy, all the better!

I have to protect a little shelve made in brass, that will be in the shower cubicle of a very demanding customer...
(The image depict the raw piece, it has to be sanded/bushed/polished, and cleaned of course)

Many thank for your tips and merry easter!

david

I just completed the audio portion of this build, and am quite happy with them. It uses a pair of Dayton Audio RST28F B-stock tweeters that have been modified slightly, and a pair of Dayton Audio SD270A-88 DVC subwoofers. The box is 25 ltrs loaded with an RSS265PR tuned to 32Hz. Since one of my PRs is a production sample and one was off the shelf, I don't know whether that is one or 2 weight slugs per PR. Measure the woofer impedance in box for best results. The box has offset panels in front and rear to keep the PR recessed and safe, and make the baffle area for the drivers at 1.5" with a removable baffle. The cabinet drawing assumes making the front 1.5" thick and no offset baffle or rear, but it is easy to make the adjustments should you so choose. The cabinets are fairly utilitarian looking at the moment with an unfinished MDF baffle and Butter-rum Formica inside a half inch birch plywood perimeter.

The name is derived from the bass response curve looking like the spine of a bipedal foraging Pangolin looking for insects or grubs, and that it and 10" 2ways are both kind of going extinct. I took visual inspiration from the DeVore Fidelity Orangutan 0/93 mainly, but the Dynaco and Advent large woofer designs of old are not too far from the direction.

The sensitivity is 88-89dB range, and definitely a 4 ohm nominal system. It utilizes the second coil on the woofer as a 0.5way for BSC. Xover is set to 1470Hz, and utilizes low Q filters and a leaned in tweeter response to minimize directivity shifts, approximating an LR4 set of slopes. It is a surprisingly dynamic sounding pair of speakers, and HD is low save for a rise in 3rd order at about 700Hz. The woofer breakup and tweeter Fs are both heavily suppressed, which notch the related drivers just outside the xover and steepens the slope slightly.

About the tweeter, and what I did to it...
The initial RST28F B-Stock tweeters measured like garbage. I was able to remove the rear chamber cap, remove the foam plug in the vented pole piece, and then replace with a better cup and a 1" cotton ball respectively. I twisted the ball into place until it was flush to the back of the back plate. I also swapped out the stock chamber-damping with Ultratouch denim, placing a layer of wool batting between the denim and the backplate. The swapped damping is thick enough to need compressed while gluing on the new back cup. I used masking tape and the included packaged protection plastic to hold the cup in place while the E6000 adhesive solidified. The spec Fs is 710, and mine spec to 800 or just north of there, so the size of the chamber was not altered much. Just use a suitable cap to fit over the backplate and glue to the backplate/magnet junction. 3" PVC cap was just too small to fit over it, but a little sanding could make it work. I used some screw-on plastic caps for glass Ball Mason style herb jars, which are honestly just a little too big but worked well. Even if you don't modify the stock tweeter, I feel it will work well in this design. The Fs suppression should still work if the Fs is between 700 and 850 Hz.

Some tweeter notes;

• I feel the foam plug being changed to cotton ball is the BEST THING you can do to the RST. 9 times out of 10, I feel it is somewhat congested sounding and this is likely due to the foam pole plug.
• The cup as I removed it was not salvageable. It is very thin plastic. If you can carefully remove it, you won't need to replace it. Good luck.
• The plug can be reached by faceplate removal, but then the wool pole-cap also has to be removed to get to it. IME, I've seen different pole caps. One is more cylindrical and one is a formed-dome shape. Shaping the cylindrical wool cap like a dome carefully with a pair of scissors ensures no contact with the output dome under operation. If doing this, be careful and don't slice the sealing ring against the front plate to keep the faceplate sealed against the front plate when reinstalled. That said, the Wool Pole-cap might fray and separate if removed, so it is easier from an integrity standpoint to remove the pole plug from the rear.
• I also applied a heavy shredded-tire/sport-flooring rubber piece to the rear of the new chamber cap to deaden any resonance under operation. I have done this several times in various cases, and it always helps a little.
• see tweeter graphic for a better understanding.

Thanks for looking!

Some people are interested in more powerful CFA amp, and this is 200W//8ohm and 400W//4ohm.
It uses lateral MOSFET output transistors like Hitachi 2SK134/135 and 2SJ49/50 or similar from Toshiba 2SK1056 2SJ162 or from other producers.
Interestin part of this amp is use of TPC compensation, but unusual one with one capacitance branch connected to the output instead to the VAS collectors.
That brings 20kHz distortion down significantly.
This thread is open to discussion and suggestions as it’s tried in simulation only.
As CFA uses very low feedback resistance there is significant power dissipation on series resistor, and I show two schematic, one with lower FB resistors and other with double values. I case if Rf is 220 ohm at full power dissipation go up to 14 W and in case if Rf is 480 ohm it halved. Still this resistor should be parallel combination resistors to distribute power dissipation. first is low FB resistance, this gives lower distortion and higher slew rate.
Damir

Zener protection diodes moved from drivers emitter to drivers bases on suggestion from JohanB (not good idea) 200W MOSFET CFA amp - Page 87 - diyAudio

Argument about stability: What is important is the outer feedback loop
200W MOSFET CFA amp - Page 67 - diyAudio

Better protection suggested by Wahab: 200W MOSFET CFA amp - Page 88 - diyAudio

First listening 200W CFA, post #740: https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-74.html#post4278243

Index:
1. 200W CFA VMOFET, the last schematic and the BOM is here on post #770 200W MOSFET CFA amp and the .asc zip file is here on page #775 200W MOSFET CFA amp

2. 100 W CFA assembling instruction on post #911 200W MOSFET CFA amp

3. PS regulator BJT version assembling and testing instruction post #912 200W MOSFET CFA amp
PS regulator layout errors post #919 200W MOSFET CFA amp
PS Regulator BOM post #988 200W MOSFET CFA amp

4. Corrected 100 W CFA schematic and BOM post #947 200W MOSFET CFA amp

5. astx real amp 200W measurements. post #851 200W MOSFET CFA amp

6. some RNMarsh real amp 200W measurements. post #787 200W MOSFET CFA amp

7. 200W CFA assembling instruction with schematic, balanced add schematic and corresponding BOMs.post #1230 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-62#post-5311565

8. 200W CFA VMOSFET printed board rev. 1.3.2 has some silk screen errors:

200W CFA VMOSFET-dado-1_3_2
Silk scree errors:

D21 rename to D8 and revers
D20 rename to D5 and revers
D23 rename to D20 and revers
D5 rename to D23
D22 rename to D21 and revers
D8 rename to D22
Q9 rename to Q5
Q7 (on the left) rename to Q9 2SC3503

explanation on page #1289 link http://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-129.html#post5539928

9. 200W CFA board rev 1.3.2, corresponding balanced add board and PS regulator MOSFET board with BOMS. page #1405 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5725721

10. 200W CFA some soldering explanation, unbalanced input and balanced inputs, post #1415.
There is silkscreen error on 200W boards rev.1.3.2, input connectors wrongly marked, IN SIG GND should be GND SIG https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5740471
post# 1506 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-76#post-6031569

11. MOSFET PS regulator testing, post #1416. https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-71#post-5740493

12. MOSFET PS regulator oscillating in some cases, remedy on post #1456.https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-73#post-5904223

12. 100W CFA board rev 1.4 and PS regulator (BJT) rev 1.3 post #1491 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-73#post-5904223

13. BJT PS regulator short connection in rev 1.3, look how to rectify it #post 1535 https://www.diyaudio.com/forums/solid-state/243481-200w-mosfet-cfa-amp-154.html#post6158297

14. Shared gerbers for 100W version #1,588 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-80#post-6929696

15. Real measurement 200W/8 at 5kHz #787 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-40#post-4314881

16. Real measurement 200W/8 at 20kHz #1143 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-58#post-5283298

17. More measurement #1172 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-59#post-5291859

18. Review #1281 https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-65#post-5457648

19. 200W gerbers https://www.diyaudio.com/community/threads/200w-mosfet-cfa-amp.243481/page-84#post-7701236

Hi,

Could someone, please, explain to me why can be seen on some design, fast op amp loaded to ground with a resistor and // capacitor before the RCA output after a serie Rsio of an opamp that already isolate it from the "true" load of the next stage ? Is it for even more stability and capacitive load ?

It's about a transimpedance circuit of a source, towards a preamp. On the preamp side it is terminated with 220R serie rigth at the input with 47K shunt and a couple of hundred pF cap to Ref as well. transmission line is a typical said 50 ohms RCA cable !

Thanks

Current feedback Mosfet Circlotron : it's alive !

Hi,

I present you the amp that I just realized.

This is a current feedback Mosfet Circlotron



Without Diyaudio forum and another French, this amp could never be created.

So thank you all the people who helped me and especially Joe Berry who gave me the Keystone of this amp, the current generator so particular that guarantee a thermal stability

A special thanks to gionag, my friend Rabbi Michele, who is the first to have made this amp and who made this great layout


YouTube : low cost phone record... but it's alive !



in real R15=500, R14=220, C3-C4= 47p







YouTube : low cost phone record... but it's alive !

I guess I never posted an intro. Oops. So much for following instructions.

I've been around other forums for close to two decades. I tend to come and go as my interests come and go. I was an electrical engineer in my first career (changed to something else after 4 years in industry watching the leadership in the companies I worked for flail and fail all over the place).

I've done quite a bit of DIY. I've built my own chip amp with my older daughter to see if she has the knack. I've built Econowaves, several lilmike horns subs, flat packs from DIYSG, and (for my first ever speaker build) a pair of desktop speakers from scratch (packed away these days and should probably be burned in a fire).

Looking at another career change after over 20 years in the current one and it'll likely be something in audio. Time will tell.

For sale is a GZLOZone PRT-01A populated preamp board with tubes and power transformer for sale. Just add RCA jacks and volume pot. I don't have any technical info as this was given to me by a friend. I will ship to you for $30 including shipping, most likely USPS priority mail flat rate box, CONUS only.

Hi everyone,

I am trying to make my own simulating tool using GNU Octave and transfer matrices methode. I am encountering difficulties in validating my simple model (infinite baffle) because it does not match hornresp results. i think i am not that far from a correct model but not here yet. as you can see phase and SPL are not the same as hornresp.

below is the code with some comments. Note that i do not think problem come from my radiatoin impedance since i used this function for analytical modeling and results mached hornresp with my analytical model.

hello everybody and thank you for taking the time to read!

I am on the quest to find some very nice studio monitors to mix on for years to come, all while not breaking the bank and not wanting to pay for things like brand image, warranty, marketing and service.
At the beginning I was on the lookout for used speakers (the likes of Amphion One15 / One18, PSI A17m, etc) as they would probably render me with most bang for buck possible, though now I have come across a few people who have decided to build their own speakers, but I have to say that finding folks who are building studio monitors specifically appears to be quite rare.
I personally am rather proficient when it comes to technology, building (woodworking), soldering, and engineering to some degree, though having looked at all the things that go into a capable and usable speaker design I am not certain building a studio monitor from the ground up that rivals the likes of ATC, PSI and Amphion is something I am capable of doing.
It seems then I will probably not go the traditional, full DIY route as for me the focus is 100% on the final product and not so much the way of getting there.
Sure, it seems interesting and romantic to design, conceptualise and build my own custom speakers, though I would probably spend a lot of money simply on all the testing, measuring and so on and so forth.

A few days ago, I came across the SEAS King RO4Y MkIII speaker kit and it seems to almost fit the bill.
On the surface, it looks like the most bang for buck that it is going to get for my application (a 3k kit that potentially rivals 10k+ speakers?).
I am of course aware that it is not exclusively the price that determines the value of a pair of speakers for ones application (the specifics matter: components, room, usage, etc), so I am unsure wether or not this Seas kit is my only good option and if it is even a smart idea to begin with.
For reference, I am in a rather small room 4mx3m currently, though it is pretty well treated with very dense absorbers and for what its worth I am getting a very good response with my (of course considerably smaller) Adam T5v monitors. Also note that this is not the room I will be staying in as I will most likely move to one that is a little larger in the near future, if that at all adjusts the equation.
If I had unlimited money I would probably buy the ATC SCM25 Pro monitors as I love their sound signature (clear, natural and forward mids with little distortion), but I simply cannot fork over the 7k (used price that is) they cost, so I am essentially looking for a similarly performing speaker that would fit my budget a little better (around 3k).

I would be very thankful for more experienced people to give me some sort of guidance as to what would be best in my current situation and if DIY (or building a kit) is the best option to go with, or if I should simply go out and buy a used pair of Amphions, PSI's, or other higher end speakers that fit my budget.

Has anybody built a set up for KT88/6550, 300B, or 845 who could share experiences and ideally, a BOM and what you did for supply voltages? I think there was talk of tailored BOMs, but it looks to me like the thread never got that far, even for the KT88/6550.

Paul

Hi all,

While thinking about ways to speed up the settling of a single-supply single-op-amp RIAA amplifier, see https://www.diyaudio.com/community/...upply-phono-preamp-design.413571/post-7702435 , I found a way to include a second- or third-order Butterworth high-pass filter. As it may be useful outside the context of single-supply circuits, I give it a separate thread.

When you just look at the topology and ignore the component values, this is a rather conventional RIAA amplifier (you could make it even more conventional by connecting R₇ in parallel with C₅, that doesn't matter much for the principle):



Normally, C₈ is used to cause roll-off in the subsonic region and the network R₇...R₉, C₅, C₆ realizes the RIAA poles and zero. In this case, however, I use C₈ to realize the lowest RIAA pole at -1/(3.18 ms) and R₇ to get subsonic roll-off.

Note that C₈/C₅ = 1000, meaning that without the subsonic roll-off, the DC gain would be 1001, a very ordinary value for a moving-magnet amplifier (1 kHz gain roughly 40 dB).

With everything ideal, at the value of the Laplace variable s where the impedance of C₈ cancels the impedance of R₁₂, the feedback disappears and the gain goes to infinity. This means that there is a pole at exactly -1/(R₁₂C₈), so if this has to be the first RIAA pole, one needs R₁₂C₈ = 3.18 ms. It's actually 3.196 ms in the schematic, pretty close.

The disadvantage of using C₈ for the first RIAA pole is that C₈, which has a relatively large value, needs to be accurate to get an accurate first RIAA pole. (C₈ has practically no effect on the gain at frequencies much greater than 50 Hz, so its tolerance affects deep bass, but not channel balance.) The advantage is that you can include better subsonic filtering in the loop by adding two more resistors and a capacitor.

As an intermediate step, suppose you could add an ideal inductor with a huge value between the output and the negative input of the op-amp, chosen such that it resonates with C₅ at the desired subsonic roll-off frequency, and that you chose R₇ such that it damps the LC circuit to a quality factor of 1/2 √2. The subsonic response would then be very close to second-order Butterworth. That's because the gain of the RIAA correction amplifier is one plus the ratio of the feedback impedance to the impedance from the negative op-amp input to ground, and that "one" is quite negligible at low frequencies. Mind you, R₈ and R₉ contribute to the damping of the LC circuit, but not by much. You could also choose a quality factor of 1 and design the AC coupling at the input for the same cut-off frequency. The combined response is then third-order Butterworth.

Such an ideal inductor is totally impractical, but it can be approximated with a T network consisting of two resistors with values much smaller than R₇ and a capacitor to ground at the point where they are connected, see this figure:



The transfer from the voltage going into R₁₁ to the current coming out of R₁₀ rolls off at a first-order rate from some very low frequency onwards, like would be the case with an inductor.

I haven't found any simple exact equations for any of the values except R₁₂C₈ = 3.18 ms. In fact, I've been very lazy and just calculated approximate values for the other components, and then used a pole-zero extraction program to fine-tune the values.

Regarding those approximate calculations:
R₁₂C₈ = 3.18 ms to get the first RIAA pole at the right spot.

The DC gain would be 1 + C₈/C₅ without subsonic roll-off, so C₈/C₅ = 1000 gives you a midband gain of roughly 40 dB.

At s = -1/((R₈ + R₉)(C₅ + C₆)), the impedance of the network R₈, R₉, C₅, C₆ goes to zero and the gain of the circuit becomes 1. As a gain of 1 is pretty close to 0, this must be close to the location of the RIAA zero. That is,

(R₈ + R₉)(C₅ + C₆) ≈ 318 μs

At s = -1/((R₈ + R₉)C₆), the impedance of the parallel connection of C₆ and R₈ & R₉ goes to infinity. The impedance of the whole feedback network remains finite due to the other branches R₇ and R₁₁, C₇, R₁₀, but it does get pretty large. That means the second RIAA pole must be close, so we get the extra criterion

(R₈ + R₉)C₆ ≈ 75 μs

The (theoretical) inductance L is chosen to resonate with C₅ at the required subsonic roll-off frequency and R₇ is chosen to get the desired quality factor. R₁₀ and R₁₁ get convenient values much smaller than R₇ with R₁₀ also much greater than R₁₂. We then have

C₇ = L/(R₁₀R₁₁)

Best regards,
Marcel

Edits:
Input RC coupling
The RCR T-network that approximates an inductor actually approximates an inductor with inductance L = R₁₀ R₁₁ C₇ and a series resistance of R₁₀ + R₁₁. At low frequencies, it stops behaving inductively, it just turns into the series connection of the two resistors.

As a result, one of the zeros of the high-pass filter that are supposed to lie at s = 0 actually lies somewhere around s = -(R₁₀ + R₁₁)/(R₁₀ R₁₁ C₇). For the second-order cases, I have used the first-order high-pass at the input to cover this zero by making the input RC time constant approximately equal to R₁₀ R₁₁ C₇/(R₁₀ + R₁₁), or actually to a more accurate value for the displaced zero found by the LINDA pole-zero extraction program.

For the third-order case, I have used the input RC coupling to make the real pole of the third-order Butterworth response, so I couldn't use it to cover the displaced zero. I used the output RC circuit in that case, or simply did not cover the zero. The effect of the zero not being in the origin is typically only seen below 1.something Hz anyway.

There is another zero not exactly in the origin, this is related to the + 1 term in the gain expression of a non-inverting op-amp amplifier. It is so close to 0 that I decided not to bother correcting for it.

16 Hz split-supply versions
This is a version for split supply and 16 Hz cut-off frequency, see post #58, https://www.diyaudio.com/community/...rworth-high-pass-included.413649/post-7927611



For the second-order version (values in parenthesis), the input coupling capacitor C₂ can be replaced with a short circuit if you don't mind when the roll-off reduces to first order below 1.3 Hz.

This is a variant with 46 dB rather than 40 dB midband gain:


Thanks to having R₆ split into R₆ and R₀, the time constant of the input RC coupling network can be set more accurately without needing awkward values for C₂. This was implicitly suggested by hbtaudio on another thread. Because of the high midband gain, the op-amp needs to have a fairly high gain-bandwidth product to get accurate RIAA correction (16 MHz gain-bandwidth product will give about -2 % error of the location of the second RIAA pole).

Finite gain-bandwidth product
See post #100, https://www.diyaudio.com/community/...rworth-high-pass-included.413649/post-7964481 , for some rough calculations on the effect of finite gain-bandwidth product of the op-amp.

From post #101 onward, Nick Sukhov points out that an amplifier with a high open-loop output impedance would result in a loop gain that depends much less on the RIAA correction circuit impedance. That's something to keep in mind when designing a discrete amplifier, you don't have the ability to choose a high open-loop output impedance when using op-amps.

Applying the subsonic filter to a discrete preamplifier based on the Hoeffelman and Meys configuration
The discussion with Nick and Chris about open-loop output impedances made me realize that the subsonic filter of this thread could be combined with a low-noise ("electrically cold") input termination resistance realized with a special feedback configuration that Dual already used in the late 1960's (CV40 phono section, see https://www.diyaudio.com/community/...o-input-load-modification.424717/post-7947176 ) and that was advocated by Hoeffelman and Meys in a 1978 AES article (Jean M. Hoeffelman and René P. Meys, "Improvements of the noise characteristics of amplifiers for magnetic transducers", Journal of the Audio Engineering Society, vol. 26, no. 12, December 1978, pages 935...939, see also Ernst H. Nordholt, "Comments on "Improvement of the noise characteristics of amplifiers for magnetic transducers"", Journal of the Audio Engineering Society, vol. 27, no. 9, September 1979, pages 680...681). The very first electrically cold resistance was made by William Spencer Percival and W. L. Horwood in 1939 as far as I know, but they used a different configuration and did not apply it to phono preamplifiers. See W. S. Percival, "An electrically "cold" resistance", The wireless engineer, vol. 16, May 1939, pages 237...240.

The schematics below show the resulting configurations. They are identical, but the left schematic is for people familiar with nullators and norators, the right schematic for people who feel more comfortable with high-gain twoports and op-amps. At frequencies well above 50 Hz, the input impedance approaches (R₁₃ + R₁₄)/(1 + R₁₃/R₁₂ + R₁₃/R₁₀). You can make this equal to 47 kΩ while using an R₁₄ that is much greater than 47 kΩ, thereby reducing the thermal noise current √(4kT∆f/R) that gets injected into the input.



You can't do this with op-amps (not without floating supplies anyway) because op-amps lack the negative output that conducts a (signal) current equal but opposite to the current through the positive output. That is, you can make electrically "cold" resistances with op-amps, but not as shown here.

Document about dimensioning the circuit
The attached zip file contains a pdf document that explains step-by-step how the component values were found (section 2) and that presents a more accurate method than I have used (one that doesn't need fine-tuning with a pole-zero extraction program, section 3). It also contains a spreadsheet for the more accurate way to calculate the component values.

Deriving the expressions was a nice exercise, but I'm not at all convinced that my more accurate calculation is of any practical use. It can very easily lead to negative or complex resistances.

As title says: I want to buy a Topping D30 (no Pro) from EU. Your offers please ...

For sale 2 pairs of line output transformers Lundahl ll1517. Tested, fully working.

€75,00 per pair or €130,00 for both pairs.

1 pair of SB Acoustics Satori MW16P-4 mid-woofers. Used, working perfectly, never operated louder than 90 db/1m.

Make a fair offer ...

I'm just building a 3-way studio monitor system and came here to get some advice when needed.

Hi everyone!

My name is Markus, I am based in Munich, Bavaria.
I have known this forum for quite some time now and have finally decided that I'd like to share some projects on here as well!
Audio electronics has been my gateway into electronics and even led me to switch my major to electrical engineering. I have been designing audio circuits as a hobby for a several years now, time and time again drawing inspiration from some of the amazing projects on here too!
After being passive for so long, it really feels nice to take the step to actively sharing as well. I really look forward to the interactions on here!

Thank you all in advance 🙂

Markus

Hi,
I am Lars from Germany. I am interested in building soundsystems and setting them up. My goal is to to help improving the sound of my techno collective.

I have the project, clear and well defined - for now on paper, but I have all the ingredients or almost, the video card is missing, but it could arrive in the next few days. for now without photos, these are the components:

¹ Soundstream Reference 300 75W*2
² stabilized power supply 14Volt 50amp
³ Big Cap - large stabilizing capacitor and current accumulator

PC
|
Sound Card
|
(this Amp)
|
Passive speaker (LS 3/5a hybrid - finished)


----- software - microphone - - - & more


These will be the amplifying part of the Desktop Audio system.

Hi All, i have a Mosconi AS 200.4, channel 2 is very quiet compared to the others, around 3-4 db. I have checked and swapped everything to make sure the fault doesnt follow and fault stays the same - ch 2 only. Any ideas? thank you in advance.

Hallo

I want to pick up the idea of JAT with his downsized JAT501. he called this small amp EZ amp. Target is lower cost , less parts and good TDH and good power ratings.
its 4 years ago and i want to restart this idea. target was 35W at 8R and 50W at 4R. he tried in his videos with 28V rail and To-220 darlington transistors. at the beginning he blow some parts and finaly he get it.
mandatory is to use a bigger heatsink and mount the bias spreader (BD139) directly at one of the output transistor.
in the video you can follow his way that he was thinking that this Darlington are as strong as the bigger transistors like 2SC5200( To-264) but you have to watch the SOA.
please remember that the target is as less parts and cheap as possible (darlington for 80 cent) to get a working amp. TO-220 housing have less heat transportation to the heat sink and so you have to watch out the heat sink. 20WATT is the maximum power what you can handle with this housing. think about the LM1875 or UTC2050 chipamps.

I personally looked at this SOA of the darlingtons. Yes it is for 30V for me critial if you want to have 50W or so. i looked at a lot of darlingtons and normally you get at the DC diagramm of SOA just 2amps max or maybe 3 amps. this is the rason why i coose just 21V rail for the first try.

i have done a LTspice with an older schematic so i used what i have to go on. i sum all comments at the videos and some ideas of the JAT501 builder thread here (red LED) the amp is working. for other FFT, OLG i need your help please. any other suggestions are very welcome. thx. CCS should have about 1,4mA to have enough current for other stages. i found no darlingtons in my LT spice so i re build it discrete.

with 1,9Vp at the input and 4R load it give us 16,8Vp at the output and therefore about 35WATT.

i try my first KICcad file since nearly 3 year - so sorry i am not an expert. its not finished and i guess i did a strange layout. but lets check first in LTSpice if this amp is working well. the kicad is not really update with some resistor values but that is the next step after working amp.

videos:
video 1
video 2
video 3
video 4
video 5

darlington: available - not so easy because a lot of darlingtons are now obsolete:
BDW94C - BDW93C...cost about 1 euro

look at the SOA and think about margin of current with capacitive loads.
if you want to have more power then you have to use more darlingtons to be on the save side. see at AB100 amp or AA9MD here in this forum.
this is not the target here.

kr
chris

variant 1: use bigger output tranistors as cheap as possible and sziklair pair like JAT501. actually TIP3055/TIP2955 are the cheapest /bigger ops transistors i found. 90W
TIP41 shold be better? TIP41 comment
very nice amp by minek with 3x TIP3055/2955 - minek´s power amp with 3x TIP3055/2955
any other 2SA1491/2SC3855 - 100W ISCSEMI can do...

variant2: use old 2SD2390/ 2SB1560 second hand from old AV amps. actually available but not cheap

edit:
17.1.2025 final schemtaic at post 20
with Darlington BDW93C TO-220 housing with 22Vrail / 4R 35WATT.
BOM at post 21

18.1.2025 changed schematic after square wave response simulation. - post 22 -JAT EZ amp done! 😉

21.1.2025 post 31 -LT spice file to play around
post 39 - Gerber file done by Peter - Kleinhorn. thx

08.02.205 add mineks amp to variant 1

2.4.2025 final amp build at post 133
final amp with measurements posts before

24.04.2025 post 135
last version LTspice and amp schematic
update the last LTspice file -last version 6 and last schematic
ideas for next version

Built it when I was quite ill just out of curiosity and to have to do something useful. Excellent performer but since it was modular (bleh!) and incomplete as a PSU I made it into a complete AC/DC PSU. A usual with friend Tombo56's designs it worked straight away without any issues when keeping to the BOM. It is officially meant as a CLC replacement as used in class A amplifiers and stuff that gets hot and uses much current for some reason, not for devices that do not allow some overshoot at power on. Read the project files for details. My user case as such is called today was a single supply class AB amplifier and a single supply class D amplifier. It outperformed my own IC based linear PSUs to my dismay and also pleasure as the latter have no overshoot so they are superior 🙂

The casing is the heatsink so an aluminium casing is optimal. I combined it with Prasi LT4320 ideal rectifier for lower losses/less heat and a 15,000 µF 35V filter cap. Had my fun, it can go.. It was pretty expensive to build (both boards) so as usual I tried with success to forget the high costs. I think 100 Euro ex shipping within EU is acceptable but let me know if you think otherwise. I removed the standoffs as I used odd non standard americano stuff. The screws are usually OK contrary to the devices 🙂 M3 hardware is of course to be used.

The sawdust is to be removed by you ! Will include a TO220 insulation pad.

I'm looking for the most suitable, commonly available op amp for driving a 600 ohm 1:1 ratio output transformer. I prefer to be able to drive it cleanly to +10 dB.

There's obviously the NE5532, but the distortion is too high for my tastes. The 4580 comes to mind, but that one isn't the best in terms of slew rate, despite the low impedance capability.

Any suggestions?

I have approximately 85 of these beauties. Ripple current 7.8A according to Mouser, who also list them at $21 in 300 quantity.

Note they come with stud, so you need a plastic nut to mount them. Or saw off and use a clamp.

Three full boxes of 25, screws and washer included. Rated at 85 degrees.

I’d like to get $10/pcs. Minimum would be like 8 of 10 pcs. Shipping at cost.

R

Bought to experiment with and no longer required.

There's a thread about these boards here:


Requires a +5v and +12 to 15v supply. I used a silentswitcher, which was perfect for the job. I swapped the included 22uf output tants for vishay bc122 solid aluminium 33uf, just because I like these as coupling caps in other builds. There's plenty of pad options on the board to try other cap types. I only had a single 2 and 3 way block to hand, hence why they are mismatched.

£50 posted in uk, international postage at cost.

I have some ground control problems, but not Space Oddity of David Bowie. That can be a nice song in the background while reading this.

This is not my first amplifier build, so I have some knowledge and have had and solved some ground problems in the past, but this one is killing me.

First picture of amplifier layout:


Normally I build dual transformer/dual psu units. This time I decided to reduce cost and used one 600VA toroid. I have tried some different layouts of wiring, but same result.
1. With nothing connected to inputs the amplifier is absolutely silent.
2. With inputs connected together with cable - each to other, the amplifier is absolutelly silent
3. With inputs connected to source there is noise - bzzzzz. Source is Marantz amplifier with preouts - no issues with other amps.
I tried to change grounds from connector to just one point, a screw in the picture on top of capacitors, same problem.
Tried ground lift with greatz, same problem.

The solving of problem was removing the connection from common ground (the green yellow) to the eart point on top near the big resistor, where the chasis is grounded. You can see now the wire on top of the screw of common ground. If I connect this to chasis earthing point there is noise. On other amplifiers, without this wire I had noise, with this one the oposite.

What is the cause of this and can I just leave it like this. The chasis is grounded to the mains jack, but the amplifier 0V -ground is NOT.

Not much info yet:

the new Quad components will be available within six months. The 303 will offer 60Wpc, cost approximately €1500 apiece, and include balanced and single-ended inputs and outputs, a remote control, a phono stage, and the original Quad’s “tilt controls.” The 303 prototype was very heavier than it looked. The classic orange buttons had excellent touch.

Click to expand...

dave

I'm searching for pair of MarkAudio CHN-110 drivers.
I'm in Bulgaria, EU.
Waiting for offers 🙂

Hello! I am Tibor from Romania. I have an old passion for music and audio systems.I have build several subwoofer cabinets and speaker cabinets, but the more I learn, the more I find out there is so much more to learn..

On a couple of threads I have promised to post the schematic for my latest (and best) version of my EL84 Ultralinear Amp. This design is based upon an ECL86 Amp design posted by Yves quite some time ago. This design uses shunt feedback to reduce the output stage rp and thus better drive the limited primary inductance of cheaper output transformers. Regardless of that, the result is good enough that its worth using reasonable quality transformers and while the common Hammond 1608 (Raa = 8K) will work well, it really deserves something a bit higher quality (more expensive). It can be used without the Ultralinear connection BUT performance would be degraded.

It UNASHAMEDLY uses Solid State to assist the tubes toward their maximum performance.

I believe it is suitable as a "newbies" first project and it will certainly out-perform most of the simple "suitable for newbies" designs I have seen here and elsewhere.

I'm off the air for the next 5 days BUT feel free to discuss, criticise etc.

Having said that some component choices were what I had in my parts bins.

Components:
All the 0.22uF/400V are Wima FKP1 - I just bought a batch of them
The volume pot could be 50K log or 100K log rather than the 220K.
The MJE340s in the bias blocks don't need heatsinks if mounted against the chassis (they dissipate about 1/2 a watt) else a small heatsink would be advisable.

Adjustments:
Set the BAL.(ance) pot for equal anode voltages at pins 1 and 6 of the ECC803S (premium 12AX7)
The 16K resistor between the 47Ks from the EL84 Anodes sets the shunt feedback level. Too much and the input stage will clip and output power will reduce.
The 12K and 470R network in the grid circuit (pin 1 of ECC803S) set the global feedback. I've used minimal global feedback.

Hope yopu like it!!!

Cheers,
Ian

Announcement!

In development - New DAC product based on the latest ES9039PRO chip with Hyperstream 4 modulator - claimed to sound significantly better than the previous versions. Multi-channel, with high Fs up to PCM1536 and DSD1024!

The wait for new oscilloscope and procrastination is killig me.

So I got a new idea in the endless chain of very stupid ideas. Making a sleeper subwoofer design, that looks weak, but sounds unexpectedly mighty for the looks.

It should be rather compact looking design or halfway in-built design into the wide "office table leg".

The idea is either a tapped horn looking style, with weak 6"-ish driver magnet exposed for view, or ported design with unimposing frontward facing 6" cone sticking out for view.

The true drivers will be one of the three:
1) Logitech Z-2300 woofer driver (basically respected 8" Tang-Band driver).
2) Mid grade 8" car audio driver with even more oomph (Hadex 338).
3) something new from Soundimports.eu

Where I'm lost is to find best decoy driver (could be a passive radiator too), making it plausible by looks, and making it move when the design is working, either electrically or as a passive radiator, that needs to be managed to not get overwhelmed by the strong driver in the background.

Ideas welcome!

Solid State Relay - SSR
I tried to find ready made SSR on web but not mach choice there so I designed my own one.
Here is SSR with quite new MOSFET driver Si8752.
I did two versions with TO220 mosfets and TO247 mosfets.
It includes DC offset detection and turn on delay.
Attached schematic and PCB layouts, if anybody interested to buy the PCB let me know.
Damir

Correct schematic is here: https://www.diyaudio.com/forums/solid-state/355093-ssr-power-amps.html#post6219435

Gerbers here: https://www.diyaudio.com/community/threads/ssr-for-power-amps.355093/page-3#post-7797854

A USSR speaker being restored.
Fascinating drivers & crossover > I think the cap's are even oil-filled.
Interesting to watch.
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Would it be possible for anyone skilled with Vituixcad to eyeball my work for errors. I am a newbie. I started trying to design a crossover to replace drivers in nice old cabinets. As a consequence, my cabinet dimensions, including driver hole sizes are fixed. I have done 7 different designs and entered each into LibrePCB and have completed board layout, but have not had any PCB built so far. Being a beginner, it sure would be nice to have a set of eyes on my work before building the PCB.
I enjoy the work and don't want anyone to do it for me, but I've exhausted what I know to check. If anyone would care to say, something like "are you sure you used the right configuration of ...", or "there appears to be an issue on graph x ..." it would be of enormous help. I attached the most basic graphs and schematic of my most likely to succeed version - there's more for the asking.

The drivers I expect to use: Dayton SIG180-04 (woofer) and Tymphany XT25BG60-04 (tweeter)

Since I feel I owe this sight some payback, I created a library of resistors, capacitors, inductors, and a few miscellaneous items - enough to allow others a pretty fast way to produce a PCB in LibrePCB. Unlike Vituixcad, my background favors this latter undertaking. I'm happy to share this library and could use a pointer of how to do it on diyAudio.

Hopefully I've not offended anyone with this post.

Thanks,
Dave

I have for sale an dual mono ICEpower 1000A amplifier that I built few years ago. I used it to drive a pair of subwoofers until one channel went silent. I tested at that time and the second channel power supply died. The other channel works normally. The amplifier modules are genuine. There is enough power in one power supply to feed both channels.
I have taken out a diy controller board for better use, it used to control power button and turning on/off the amp boards, although you don't need it to make it functional. All other parts and modules and wiring is in place, see images. Sorry for bad quality photos, the front plate does not have scratches it is just dust.

It is assembled in a beautiful PASS style smallish enclosure, roughly 10"x10"x10" size.

My asking price for the complete set is 450€ 250€. Can be shipped to almost anywhere. I'm shipping from Finland, Europe.

Calling all Calgarians!

It seems we have a bit of a diyAudio continent in Cow Town. Notably, @bxt2008, @leadbelly, @kirks, and likely others. In a recent thread I floated the idea of a get-together over a few pints at some point and there seemed to be some interest.

So how about this: We meet at Two Pillars Brewery (910 Centre ST N) at 8pm on Wednesday January 15, 2025. The idea is just to put a face to the user ID and to chat/BS about all things audio.

Please respond below by January 7 if you plan to make it. If it turns out we'll be more than Two Pillars can accommodate I'll find a larger venue that's reasonably central.

Hope to see you at Two Pillars!

Tom

Hi Guys,

Just seen a recent press release on the new Hypex Fusion plate amps. Look like game changers for active speaker technology. I can't wait to try these babies out. Press release here:

Hypex Electronics Introduces New NCAS500MP Active Speaker Amplifier Module

Hello. I have read a number of rules of thumb about mid tweeter driver spacing. I'm wondering what the actual process looks like for y'all

Here is how I have opted to do it for the project I'm working on now. I'm mating the Dayton ND25FW tweeter to the Dayton DS90 mid. I looked at manufacturer supplied graphs, and figured anywhere from 3-4KHz would probably work as a good crossover point. I settled on 3700Hz as a starting point. So I used the kimmosto rule which specifies the wavelength of the crossover point * 1.2 should be your CTC spacing. In this case
3700Hz is 3.66".
3.66*1.2= 4.392
So I made the spacing 4.4", and have 3700Hz as my starting point for crossover work.

How do you guys do it? I know some people just put them as close together as possible. I've heard below 1 wavelength CTC as another rule of thumb. I'm assuming some people use sims like akabak. I wonder if anyone makes vertically adjustable baffles and plays with spacing until they find a sweet spot? I'm just interested in the process here among other DIYers.

Let's place all the Bass shelter OT stuff here. Cabinet/structure tech is applicable to more than subs and cover multiway and full range too. And we have all the dev work with CAD, electronics, mechanical and much of the cross category stuff

Active projects
Phoenix
Racer 8
Heaving Bed

Well , it started long ago …. when I was really young(st)er, full with naivete and BS , came to pretty novel idea to make xformer loaded tube line stage …
Result of first tests , hardly optimal ( using two halves of 6SN7 in parallel and loaded with ancient xformer from vertical section amplifier of ancient B-W tube TV set) , I was blown with ‘till then unknown dimension of sound – everything was so alive ….
Later I made several iterations of line stage with same approach , being so proud for reinventing boiled water , until I got some xerox copies of Sound Practices , where I found that even in boiled water reinventing I wasn’t first ….. boyz from Italia already made Euridice preamp ; anyway , intermediate iteration was with two halves of 6DJ8 in parallel , latest one being with ubiquitous EC8010 and custom made xformer . That being even published on my old site – WOT preamp and battery charger 😉

Selling a preamplifier (passive). Control via encoder or remote control.
Four inputs and one output.
A logarithmic attenuator is used as a volume control.
Attenuation -96 dB, adjustment step 1.5 dB, option on Vishay 1% resistors, FUJITSU relay.
A 32 * 8 LED matrix is used for the display.
After switching off, all pre positions (channel, volume) are remembered.
The amplifier has an absolutely neutral sound.
Display brightness adjustment and the ability to completely turn off.
Remote control included. Price $300 plus shipping.

A stepwise volume control is implemented with a set of tiny relays and resistors. In a high-end audio system, a noticable sound improvement over potentiomeneters is obtained, also compared to 'audio grade' potentiometers. Its IR remote control provides convenience over solutions with stepped attenuator rotary switches. The sealed relays will maintain contact quality over a practically endless lifetime. The design represents a audio 'preamplifier' of top-class sonic quality, in a compact and affordable implementation.
The design uses high quality Fujitsu FTR-B4CB4.5Z bistable relays, as well as mil-grade audio grade resistors RN55D, RLR07, CMF55 from Vishay-Dale, which have an excellent reputation in the audio field. The circuit is designed for high-quality audio applications.
The input impedance is constant 10K, 22K, 50K, 100K.
The 1.5 dB adjustment step covers a sound attenuation range of 94.7 dB, 63 steps. By eliminating any active electronics, a very clear and open sound is maintained. There are no clicks when adjusting the volume in the speakers. Encoder for control from the panel.
The IR receiver allows remote control. When the power is turned off, the last volume position is remembered.
The circuit operates from a stabilized voltage source of 5 V.

The input impedance is constant 10K, 22K, 50K, 100K.

Payment is possible via Payoneer or to a bank card. It is also possible to buy on Ebay.

Stereo controller kit (2 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver

https://www.ebay.com/itm/267166457170
https://sgaudioua.etsy.com/listing/1798144856
https://sgaudioua.etsy.com/listing/1871270901
Stereo controller kit (2 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
Input selector for 4 stereo channels
https://sgaudioua.etsy.com/listing/1825237975

https://www.ebay.com/itm/267166457170

https://www.ebay.com/itm/266863103276
https://www.ebay.com/itm/266932731942
https://www.ebay.com/itm/267151831175

Stereo controller kit XLR (2 channels XLR), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
Input selector for 4 stereo XLR channels
https://www.ebay.com/itm/267197617946
https://sgaudioua.etsy.com/listing/1824028825
https://sgaudioua.etsy.com/listing/1825237975
https://www.ebay.com/itm/266918250389
https://www.ebay.com/itm/266936692441

Stereo controller kit (8 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
https://www.ebay.com/itm/266863035366

Stereo controller kit (6 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver

I have been considering both of these drivers for the HF of a music speaker system that will cross likely to a 12 or 15" woofer that is yet to be determined. Obviously there are huge differences in these drivers, but am wondering how much HF I give up by going with a crossover a little lower and using the HF146 vs the HF10AK? Graphs tell me only so much, and wonder what others have experienced or implemented to close the gap - if at all possible!

At present I own the B52 clones of the QSC 1" guide and a pair of 18 Sound XT1464. My system is triamped with a DBX Driverack 260 handling DSP duties.

My intention was to do ULF likely with some 18" JBL 2245's, so I am not sure if there is anything to gain going 1.4/15" vs 1/12". I certainly wouldn't like to sacrifice HF, since LF is less of a priority due to the JBL. Maybe I just answered my own questions, but without asking, I am unsure if anyone has had experience/success comparing these drivers/guides.

Search has shown the XT1464/HF146 combo to be nice, and lots like the HF10AK for how smooth it is... would it mate well with a guide like the QSC everyone likes so much? I'm certainly open to suggestion as well.

Been a log time reader and now working on a diy kit.

This thread is now a Sticky for you all to post pictures of your Analogue Line Level diy efforts and projects.

Please try and keep the thread on topic and take any technical discussions over to either a new discussion thread or the original thread if there is one.

Hi !

I built the Jean Hiraga 30W Amp, and I absolutely love it's sound. Its my main amp as of now. But the DIY bug continues to prod me to strive for something even better. Hence this question.

in your opinion, which Amplifier, whether Class A/AB/D will you rate as giving a (distinctly audible) better quality sound than the JH? What did you find better. If you have done an A/B comparison that will be great.

Thanks. !!

Hi everyone,

I would like to share my thoughts after trying to modify the worst sounding speakers in my modest collection - a beautiful pair of Blaupunkt Lab 208. They look like a million dollars but have problems with HF (very directional), boxy sound even when not hanging on the wall and almost zero bass under 100 Hz. About 5 l netto volume, closed cabinet with two (Audax?) 13 cm woofers and one paper cone tweeter. They even have a proper crossover with two solid air inductors and two bipolar caps.

The first thing to check when addressing the boxy sound was a textile mesh under a wooden grill (a wooden one with several holes about 11 mm diameter and 3 mm depth) strengthen with some transparent paint. This textile dust protection under wooden grill was so glued with some hard chemicals that under magnifying glass only one per 10-20 micro-holes was open. So first I cut out the textile protection from all the wooden holes (baffle) and replaced with an "acoustic transparent" open cell foam.

To my surprise it brought no effect. No impact on overall SPL or SPL in frequency domain graph. Zero. Null. The boxy sound remained, which was even visible on the measurements (REW, UMIK-1) in the form of a 120 Hz peak before very early bass roll-off. The next solution I came up with was to remove one of the woofers to change the system overall Q value to alter bass roll off characteristic. And yes, that brought some improvement (of course I added an L-pad to the tweeter and parallel resistance to the remaining woofer to match, sealed the baffle hole in place of missing woofer) but the boxy character remained. Replaced not-a-good-looking damping material with polyester wool (3M calls it Dacron) - no effect.

After some research to find the remedy for too small cabinet (these boxes are only 10 cm in depth) I found - that was what I had thought - a solution. Variovent. After reading several sentences on the web telling "oh, I just added a variovent to my subwoofer and it improved bass extension very much" I decided to give resistive loading a chance in my Blaupunkt Lab 208 speakers. As engineering of such s port was not very demanding, the Blaupunkts quickly received a stuffed area under the grille in place of a missing woofer.

And now... I am not sure what to tell 😉

After experimenting with different damping materials, port area, port diameter and damping density, there is inly one thing I can tell: resistive loading does not extend bass. It was obvious after first measurement and proved with the following ones. First thing was a drastic early roll-off on the LF side of graph. And the second was a change in a system's resonant frequency which increased so significantly that it made such a speaker system virtually useless.

As I do not have a specialized gear for impedance measurements, I did it the traditional way with a serious resistor and analog multimeter. Started with the whole "variovent" closed, so the closed cabinet. The woofer has Fs of about 45 Hz. In the closed 5 l cabinet with the other sibling woofer it increased to 100 Hz and with missing second woofer to 85 Hz. That was the starting point. And then I uncovered the holes in the wooden front of the baffle where a resistive loading port was located, one by one. The results destroyed my faith in this "variovent" solution.

Two holes of a port open - 120 Hz. 5 holes - 145 Hz. 15 holes - 185 Hz. And then up to about 220 Hz of a system's resonant frequency with a "variovent" port fully open. "Fully" means an open surface calculated with some equation found on the internet. And now the question comes: does resistive loading make any sense? Is it really a solution for too small a cabinet? Because from my point of view it is only usable in a very low tuned system, to make impedance curve less aggressive, but always at the cost of bass extension.

Could anyone please say or prove that I am wrong? 🙂 I am pretty sure I am because there were several constructions with resistive loading, can be found on the vintage market and they had to be working as some of them are classics. If you wish, I can share some photos of the work with the Blaupunkts Lab 208 as they are too pretty to believe they play so bad 🙂 They are very solid and beautifully made as a furniture, but have so many sonic problems it is hard to believe they made success on the market. Comb filtering of the tweeter signal because of a drilled-holes concept of a baffle? Not sure yet, but that could also be the case 🙂

Vario-vent, or not to vario-vent them?

Regards,
Mike

I'm looking to buy 12" woofers for OB midbass and have narrowed down to these:

• Acoustic Ellegance LO12 - $639 - designed for OB applications
• Beyma 12BR70 - $155 - used in the Caladans with very good comments
• SB Audience Bianco 120B150 - $99 - designed for OB applications

Below these midbasses I have sealed subs playing from 70Hz, and above them have an 8" in OB and looking to cross them at 400Hz.

Anybody has experience with two or three of these to compare how they sound/perform?

I also need to decide between having 1 or 2 per side.

Thank you!

Hi, I’m interested in building a pair of MicroWalsh Tall clones. I was only able to unearth one thread from a decade ago, and all of the pictures and links were dead. User “Critofur” was instrumental in their development, but hasn’t been active here for a couple years it looks like. Anyone ever done a set?

Building the power supply for my Wolverine and inspired by the incredible build photos from @stuartmp and @danieljw, I decided to learn KiCad and do my own dual full-wave bridge rectifier pcb. I would have used the one from @prasi, but I wanted to use screw terminals instead of quick-connect tabs. That's the nice thing about doing your own -- you can use whatever hardware you prefer. So for anyone who hasn't taken the plunge, I highly recommend it. It's really pretty easy -- KiCad is amazing -- and quite fun. So thank you to @stuartmp, @danieljw, @prasi, and @xrk971 for the wealth of info you've shared in these forums that inspired me to take that plunge.

Fwiw, here's what I came up with. It's an active rectifier using the LT4320 Ideal Diode Bridge Controller like @prasi's combined with features that I see in the photo of @stuartmp's dual bridge rectifier pcb. So it's kind of a hybrid between the two. The key features are:

1. Dual active rectifiers using the LT4320
2. Can use either screw terminals or quick-connect tabs
3. Supports a ground lift circuit to connect to chassis ground
4. Supports indicator LEDs onboard, offboard, or both
5. Supports bleeder resistors
6. Supports the RZ/CZ components as on @stuartmp's pcb

Confession: I'm not sure what RZ and CZ are for. I included them just because I see them on @stuartmp's pcb. I assume the Z stands for Zobel, so I've been reading about Zobel networks, but I still can't map what I see in the pcb photo to what I've been reading. And that's my ulterior motive for posting this. Maybe someone can answer this question for me.

Hello to everyone. I'm having troubles with an old Rega Elicit MK1. It sounded so nice and it was a robust system, since it met my grandfather. Actually not himself, but his illness. He's not able to remember things, he probably made a misconnection... so, I thought, that's a bit of a complex repair... and I'm not sure if it's possible... but I'd like to make him listen to his collections again, and here I am.

Diagnosis: The amp was dead, no power. So I opened it, and found blown fuses, and quite some damage.
I took a photo of the incriminated section, which is on the power side of the left channel. Ouch!



Following the schematics I made some basic tests with a multimeter and a transistor tester. I've found and replaced a list of parts that were damaged, which include the finals (2SC2922 and 2SA1216), the BD139 and 140 which were totally blown (T14, T17, T18, T13, T21, T22) as the 100uF capacitor C30, the big resistors R11 and R12 (blown!) as well as R18, R36, and R49, and some zener diodes. T48 on the -39.5V was also tested bad, but with no visible damage.
I remade some tracks that were vapourized (ouch), I tested the other small transistors too (only in the amplification section of the board), and they were all good.

Feeling quite confident I powered on the amplifier, and there was life. Connecting a speaker (the right one) revealed sound! I did a rough impedance test, I swapped the channel, it sounded amazing. hooray! You might think... 🙂
Because after some time... a POP was heard! But the amp was still on, so no fuse was triggered. I power cycled it, giving some time to cool down, thinking it was the thermal protection.
Nevermind, the music played again.
Remember I did the test in mono, because I had only the right speaker at that time. Later inspecting the other speaker (left) I found one woofer's coil stuck upwards, cooked to perfection. Replacement of the woofer done, but the internal connection of the loudspeakers' crossover was not clear to me. The loudspeakers are the Rega XEL. I can provide more detailed information if needed.

Anyway, the first stereo test was made...
Sure enough, after less than 2 minutes, there was the POP disconnection sound, much louder at the left speaker (the one that I repaired), and the sound went mute. Power cycling the system "resetted" the protection (the DC one?? I've read that the thermal protection turns the "Elicit" front LED red, but I'm not sure about more localized protections, if that was a protection at all) but the issue persisted, so I opened it again and found R36 and R49 burned again, on the left channel. Was that for the impedance of the left speaker, the one that was blown and repaired, not being high enough? Was it the crossover's fault, or the amp still has some issues?

And that's where I'm now. I also found a cold solder at LED3. That is to see the +39.5V, and it's the only led that turns on slow and turns off fast. Maybe that was only that solder joint that triggered T25, which caused the pop?
There are some big capacitor which hold a lot of charge, and don't think they'll discharge after days, like I did: you need to discharge them, I learned the hard way 🙂 but when holding charge, the finals show short?? I don't know.

Your help is very much appreciated; I'm absolutely no audio technician or expert, forgive me for the technical mistakes I made, and thank you for your patience reading all of this.
Ciao!

I just have to post this, maybe the best beef, not just brisket, I have ever had in my life and I have had ribeye at Ruth Chris and generally BBQ very well using far less expensive but well raised beef.

Snake River Farms Wagyu Corned Beef.

If you know good meat you either or should know about SRF, some say best in the US and one of the best in the world, might be, sure dang expensive as a 12oz ribeye is $64, 32oz porterhouse is $129 or so.....each, ouch! At Costco they had the Corned Beef Brisket at $8.95lb which is quite high for that cut compared to other brands but had to give it a try. We picked up a 4lb one and cooked it at lower temps for hours in my Grandma's very old dutch oven, towards the end red potatoes, carrots, celery, all organic and good quality, forgot to grab some organic cabbage but still dang fine, getting cabbage in the morning!

Oh my, I am simply blown away as to how good it is and one heck of a value at the price.
We did not even use the good horse radish or mustards we have, just not needed, just the seasoning packet, which normally I throw away but it looked pretty good so tried it, it was perfect.

My next favorite is a pork rib roast slow cooked on the BBQ on indirect heat, mmmm.

With a last name starting with Mc....I have to do a bit of celebrating this time of the year🙂

Rick

So, I really hope someone with the knowledge and a generous heart can help me.

So, I have a HK990 amp and was doing the bias adjustment as my right channel was running hotter than the left. Looking at the manual, it says this:

AMP Adjustment Iding Adjustment
Precaution for handling measuring instrument.
The ground side of the measuring instrument to be connected to the speaker terminal of this unit must be kept in floating condition because this unit is equiped with the floating balanced power amplifier.

So what's the problem, you ask? Yep, I shorted the probe between the pad and something else, maybe normal ground.

The slow blow fuse blew, needless to say, as does the replacement fuse.

Steps taken so far:
1. Disconnect the transformer for the right amp and power up. No problem, everything works as usual with the system and the left amp.
2. Examine fuse board - nothing burned or odd found.
3. Removed and examined RHS amp. Visually, I found nothing. No burn marks. I tested, in circuit, the output transistors and they all behaved the same. I didn't fully disassemble the heatsink so the diodes mentioned in the schematic might not be visible.

So, needless to say, I need help. I've rebuilt numerous amps without doing something so stupid before, so I feel confident in replacing components to fix this, I just need guidance.

Attached are the schematics and parts list.

Please help with any suggestions on where to start. I'm actually out of town but willing to add components to an existing order on the chance that it's the problem.

What do you guys think?

Thanks for your time and take care,
Peter

tl;dr: I built 2 Linsley-Hood 1969 amps from kits I bought on amazon, swapped some parts, and they are amazing.

So I gotta be honest, of all the diy audio stuff I get into, I have stayed away from amps because the waters seem so full of snake oil, and also, I'm afraid of shocking my nuts off with 1000 watts of accidental test tone. Anyway, a friend got the hook baited just enough for me to bite, and I bought that Linsley-Hood 10W amp that you can buy on amazon right now. A cute little kit with all the parts, and it's a mirror-imaged stereo PCB setup, to boot.

I built one up, it tested ok, but I wasn't much moved. Immediately suspected that the components that came with the kit were worth testing. One thing I do know is that a good Class A amp should sound super nice and clean, which wasn't what I was hearing. (Whenever I hear a known good Class A amp, I'm usually pleasantly surprised.) I popped out the power 2N3055s and sure enough, the Beta values were all over the map. I bought a bunch of legit ones from Mouser, tested them all (they were great; the beta values were consistent across the entire batch), and installed those, then replaced the coupling caps with better ones. Not like, break-the-bank prices, just good ones from Mouser. Like $8 or so for film and $2 for electro.

Anyway, I put it all together and matched them up with suitable meanwell power supplies and put it all in a little red tool box.

Boys, it sounds freaking great. Really, really good. I haven't even dialed it in yet. Tests on the scope look great. Passes audio beyond 100kHz.

Inspired by New Record Day video about the Caladan by Clayton Shaw, I decided to do it DYI since shipping costs to Japan are ridiculous (and no international deliveries at the moment provided). My MiniDSP serves as an active crossover for two ICEPower 125ASX2 amplifiers. They sound amazing, using a Linkwitz-Riley filter 48db at 1kHz and some gain in the low end, Never thought open baffle speaker can have such a lot of low end, while the speaker membrane is barely moving. The speaker disapear and you feel like in a live concert. This works also for my music with distorted guitars, not only for the high end demo music. Bass guitars sound so real. This is the first day listening to them after waiting 3months for the delivery of the 12inch speaker drivers....I guess no burn in needed. Clayton Shaw chose the perfect drivers.....

Genelec GLM IR remote volume control DIY prototype.

connection:
L-out to 3.5mm tip, L-ground to 3.5mm ground.

potentiometer :
Alps 50K motorized.

This might seems a dumb question, but..

What signal phase delay (input/output) is considered normal in a 2 stage, passive riaa- tube phono amplifier?

Anyone ever consider doing a Orangutan clone?
What drivers would you use?
Looks like the SEAS 10", but that only states as 89db.
The Orangutans are 93 & 96 db
Any thoughts?
Thanks
Mike

I'll try my best to inspire and to show to you that everything is possible. To do a multicellular horn takes a while due to all different moments but they are all kind of nice and it feels good to see the horn grow with every hour of work.

These horns are NOT a Altec 1505B copy. They are pure exponential with a flare frequency of 183 Hz, the same, or at least what was my and reVintages intentions bacause the throat flare in JBL 2441 and 2445.

The horns are built out of 3 mm Baltich Birch plywood, filled with polyester and the outher sides are covered with polyester and glass fibers.

Enjoy😎

Hi all, I am considering a 250.8 as a replacement for my current amp - PSA BHK 250.
I am facing a possible relocation to Europe from the US though and will move most of my equipment as well. Is this possible to convert the 250.8 power supply for 220v operation? I did read somewhere in these pages it being possible with a previous version (i think the 250.5) but not sure. All my other gear preamp, DAC etc can have their wiring adjusted for 220v.
Many thanks

Hi, I'm a musician and love audio. I'm looking for ways to ways to make my instruments really loud and really weird

I am going to make up a stereo unbalanced cable to replace some with a break in them for a headphone application. They will ultimately be terminated in 3.5mm jacks.

I am fully on the "cables don't make a difference" train when it comes to audio quality, but I also do know that good quality cables are more robust and generally nicer to handle.

I normally just go with Van Damme + Neutrik/Ream connectors. But I can't find a Van Damme cable that seems suitable for this application. This is the closest I could find:

https://www.van-damme.com/vandamme_product/van-damme-reduced-od-console-cable/

Using the shield as common ground - but I'm not actually that's correct, and also whether having the L & R as a twisted pair is "correct" either. Finally as it's designed for console use, I guess robustness is possibly also not a primary consideration.

So in short, does any one have any recommendations for decent cable to use for headphones.