Most transparent amplifier for studio monitoring

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Obisix

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Joined 2015
#1
Hey guys!

I am about to finish buying my new house and since I am a sound engineer I'll make a mixing room for my new monitors.
However, I only used active speakers before, and I'm now changing onto ATC's SCM11, which is passive. I really loved its sound compared to the Genelec 8040B, which had too much bass and it was smudgy compared to the crisp sound of ATC!

I would need suggestions for an amplifier build which is really accurate and clean: I only need them for the monitoring process (for audio listening, I have else)

I have searched the forum but found no answer in this year, so maybe if I ask this now, I can have the most fresh answer.

Thanks for helping!
Sebastian
 
#2
Obisix said:
Hey guys!

I am about to finish buying my new house and since I am a sound engineer I'll make a mixing room for my new monitors.
However, I only used active speakers before, and I'm now changing onto ATC's SCM11, which is passive. I really loved its sound compared to the Genelec 8040B, which had too much bass and it was smudgy compared to the crisp sound of ATC!

I would need suggestions for an amplifier build which is really accurate and clean: I only need them for the monitoring process (for audio listening, I have else)

I have searched the forum but found no answer in this year, so maybe if I ask this now, I can have the most fresh answer.

Thanks for helping!
Sebastian
Click to expand...
Hi,
Not my personal experience but based on opinions of others that have actually one, VSSA and its derivative PEECEEBEE in the builder's opinion, provides the most transparent sound, with good slew/high bandwidth/Low THD. Again , to drive home the point, its opinion of builders here and not mine, atleast not yet, as I plan to build one for myself, both VSSA and PEECEEBEE
reg
Prasi

Edit: Just saw your speakers can handle 300W, may be you need Lazy Cats's "First One". (search the forum.)
 
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#4
prasi said:
Hi,
Not my personal experience but based on opinions of others that have actually one, VSSA and its derivative PEECEEBEE in the builder's opinion, provides the most transparent sound, with good slew/high bandwidth/Low THD.
Click to expand...

There s a fashion by here that brand those average designs as transparent and high perfs, wich they are in respect of amps dating from 1970 or so, but with the current available transistors i would call transparent amps with FFTs like the one below...
 

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#5
Those SCM11s, whilst lovely do tend to like some power. I would consider 100W-200W range for them. My advice if you are unsure is to build a honeybadger. Most parts available from the DIY store. But there are many other amazingly good designs on this site.
 
#6
Wow thanks guys for the suggestions, but I still don't know what to do.

I will surely check out PEECEEBEE, Honey badger, and Ian Hegglun's amplifier!
Any more suggestions on the most transparent amplifier?

Thanks for the help guys, appreciated <3

Edit: Wahab, can you suggest me a transparent amplifier that has almost identical distortion and transparency you are talking about? That would be lovely!
Thanks!
 
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#8
To me the most transparent amplifier ever, is this:
circuit49811_1.jpg

Can do up to 100W, if needed. But crank bias down to <300mA.
All parts end of life so be quick if you want to make one...
Output stage transistors 2SK1529 and 2SJ200.

The 1W1kHz8R THD is unmeasurable with my test rig. My test rig loop back THD is only 0.0009%... If I put this to the chain the THD still is 0.0009%, so do the math from that...
You of course need a good PCB to get the performance to that level.
 
#9
#10
I wouldn't dare to place my opinion unless first know what are you mixing ....

For example if you are into techno music you are NOT going to go very far away with 600ma of bias in Class A amplifier no matter how transparent is the sound.

Answer i mix everything is not valid as amplifier that is unconditional also not exist

All typologies can and will have different behavior depending on the type of music program .

Transparency is one demand but there is a few other things that will play significant role in the choice of amplifier ....Transparency on its own is not enough criteria to complete your request .

It is common knowledge that electronics engineer speak different language than musicians and often sound engineers but i expect that you will work this out.

Difference is that an electronics engineer can also do sound engineering though the sound engineer cannot do or understand electronics ....

Kind regards
Sakis
 
#11
wahab said:
There s a fashion by here that brand those average designs as transparent and high perfs, wich they are in respect of amps dating from 1970 or so, but with the current available transistors i would call transparent amps with FFTs like the one below...
Click to expand...

Hi Wahab,
I agree with you , but like I said I was merely stating builder's opinions here that I have read in this forum.
 
#12
building amps is for electronic hobbyists

not for cost saving, and quite arguably not for any audible improvement - transparent was achieved long ago

$10k reward didn't get taken in "few thousand trials"
https://www.google.com/#q=richard+clark's+amplifier+challenge

Stereophile's Golden Ears failed Carver's challenge with their choice of "SOTA Tube Amp" vs Bob's $600 SS with a few tweaks to null response differences

jcx said:
Geddes tested for low level linearity, bought amps for $150 at Costco

Geddes doesn't seem to think "transparent" audio electronics is hard to do, and good enough electronics can be had very cheaply

his waveguide speakers, selling for $3k each, were demoed with < 3% of a pair's price in his mass market consumer amp
Originally Posted by gedlee
You can believe it or not, but its true. I tested about five amps that I had and the Pioneer was the best.

People always take my statements out of context. Once one has good electronics - and clearly price and "personal perception" don't correlate with good - then the only thing that matters is the speaker and the room (source material being a given). I have never said that any piece of junk electronics is fine. Only that very inexpensive and readily available electronics place the electronics into the "insiginificant errors" category.

I know that this is not a popular position and it's not one that I have always held, but I have studied this problem intensely and this is my conclusion. It is, by the way, the same one as held by Flyod Toole and Lauri Fincham and a whole host of other well know audio researchers. It's amp designers and marketers who seem to hold contrary beliefs

Quote:
Originally Posted by gedlee
No hardly - I don't "favor it", but I was severly chastized for using it at RMAF when, in fact, no one really knew if it was any good or not. It works just fine as my measurements show. I would not use this amp for many applications, but it suited my point at the time, which was that loudspeakers account for 99% (well you could argue 98%, but you get my point) of the audio systems sound quality.

The amp is a Pioneer DSX-V912 - a receiver. The point is that it was on sale at Costco for $150.00. I bought several of them for home theater use. I used my test to measure the amps and they were quite good actually. Especially for chip amps. I was measuring a lot of chip amps (a survey of capability) and most were pretty bad. As a chip amp this unit deffinately stands out. It compared quite favorably to a very well engineered discrete amp that I also use.

I also tested several other receivers and they were almost universally bad.

Quote:
Originally Posted by gedlee
Crossover distortion is a particularly insideous form of nonlinearity because it happens at all signal levels and there is no comparable mechanism in a loudspeaker to mask it. The question was asked if I have a way of identifying crossover distortion in an amplifier.

Yes, I do.

You see the situation with crossover distortion is that the % distortion increases with falling signal level. This is exactly why it is so audible since this is directly opposite to our hearing.

One could therefor ***** crossover distortion by looking at THD as the signal level goes lower, which is a typical measurement. The problem is that virtually all of these THD versus level measurements are THD + noise. When this is the case, the rise in THD at lower signal levels is actually the noise and NOT the distortion, but it is impossible to tell which is which. SO this test actually masks the real problem. One would have to track the individual harmonics of the waveform, but then the noise floor is still an issue.

Hence the measurement problem is one of noise floor and how to measure distortion products down below this floor.

This is done by averaging. But normal averaging can only lower the noise floor so much - down to the noise power. But if I have a signal and I average this signal sychronously then I can raise the net signal to noise level. This too is common. But if the signal does not exactly fit the time base then I need to window it and the resultant spectral leakage makes this sychronous averaging less effective.

I use a signal that exactly fits into the time base of the A/D taking the data. This means that I don't have to use a window and I can sychronously average a signal to noise ratio that is about 20 dB better than a simpler test could achieve. This means for example that the input signal needs to be something like 976 Hz, not 1000 Hz, which doesn't exactly fit the window.

I actually had to generate the input wav file in FORTRAN using quad precision, special random number generators and rounding techniques, because the test signals needed to have a 120 dB dynamic range - very difficult with 16 bits.

I use a signal that starts out low and goes up in level. I plot out the results as the signal drops into the noise floor. This test shows vast differences in amps that measure identical with standard tests.

It also shows that my Pioneer amp - you know the "really crappy" one that I get crticized for using at RMAF - is an extremely good amplifier. As good as the best that I have tested with this technique.


basically if you're serious about improving audio reproduction with finite time and knowledge - don't build amps - just buy cheap adequate ones, spend the time and dollars on speakers and room
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#13
Sadly I can't afford the good Dr Geddes' fine speakers. Which is handy as I can't fit them in my living room either 🙂. Them being 95dB/W and not being asked to do low bass of course does help!

In this case with OP having 85dB/W speakers that need some grunt what is out there with a clean >100W though. (edit the pioneer at 100W/8) would just scrape in, but an extra 6dB might be useful.
 
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