ETI 5000 MOSFET Power amp

[suzyj]

Originally posted by nsaidor
Have anyone else build this design?

Did you get the same measurements as Suzy got?

How's the sound quality compared to Krell clone KSA50 or Leach amp?

Cheers
-Navin

There are a few people in Romania building them. See http://www.elforum.ro/viewtopic.php?...0919a6f#136428

Feedback that I've had has been very positive, though I haven't seen any other objective tests.

If you're considering building some, make sure you can get the SST404 dual JFETs before you commit to getting boards. Siliconix have stopped doing JFETs all together. Mouser used to sell the Siliconix ones, but no longer stocks them, which is a real pity. Calogic and Linear Systems (who may be the same people) appear to be the ones who actually make them, but my attempts to get small quantities (50) have so far been completely fruitless.

[janusz]

Hi,

To those interested one may use 2n3958 monolithic dual jfet instead of the venerable sst404 or ls404. The above 2n series jfet is currently being sold on EBay for $3.95 by activeparts.

cheers,

[janusz]

Sorry, it should be ls844 or ls843
cheers,

[polcad]

Hi,
I also want to buid Suzy's power amplifier. I looked at the schematic and I don't see any thermal compensation of the output power MOSFETs .
Did anyone build this amp and used for a longer period of time driving it close to max power?
How does it behave when hot?
What do you think about adding a thermal compensation ciruit?

[vitalica]

It is the best amplifier that I did!
And there were many
The sound is perfect!
And the bass ... superb!
After hours of working is very stable.
I am very pleased with this amplifier, I had 6 channels home-cinema.

Suzy ,thanks for your effort to projects are the amp!!

[vitalica]

Some pictures

[nsaidor]

I still could not get all components as they seem not available here in Sri Lanka. I tried Farnel, esp. SST404 dual JFETs could not be found. Is there any suggestion for a replacement. Not sure how good the 2n3958 is?

Originally Posted by vitalica

Some pictures

vitalica,
Did you compare this with one of Krell clone KSA50 or Leach amp, if you have already built one of them?

[Trevor White]

Originally Posted by AKSA

Suzy,

You come out very strongly in favour of zero measured distortion and justify this with purist, engineering notions of correctness (and convention). It is difficult to argue against this, but how do you explain the huge popularity of the SET, with its horrific measured distortion? I don't want to challenge you or be rude about this, but you might ponder that an amp is not just a scientific apparatus but also a musical instrument, and that the two purposes should be complementary......

Cheers,

Hugh

The same reason people like tone controls and loudness switches.

Does it make it correct just because they are popular ?? NO !!

And since when was it the role of an amplifier to color the signal ?? Surely that is the job of the mastering engineers and the musicians and not the reproduction equipment which is supposed to faithfully reproduce what is fed into it.

regards
Trevor

[suzyj]

Originally Posted by vitalica

Suzy ,thanks for your effort to projects are the amp!!

Thanks for the compliments. It makes me really happy that people are getting enjoyment out of my work.

I've got a couple of different variants at home - the main 140W/channel ones in the loungeroom, as well as a smaller 50W/channel one that I did for my study. Both have performed flawlessly in the few years they've been running. The one in my study especially occasionally cops a hiding, when I'm in the mood to play my guitar really loud (via a pod DSP guitar amp emulator), but it's never missed a beat.

Originally Posted by polcad

I looked at the schematic and I don't see any thermal compensation of the output power MOSFETs .
Did anyone build this amp and used for a longer period of time driving it close to max power?
How does it behave when hot?
What do you think about adding a thermal compensation ciruit?

Lateral MOSFETs have a negative temperature coefficient, so they don't go into thermal runaway. That's one of the really neat things about them, and one of the reasons (along with lower Cgs and Cgd) they're so popular despite their really low Rds.

So no, no thermal compensation. This amp runs reasonably warm anyway due to fairly high bias currents. Even after I give it a thorough hiding it drops back to idle temperature quite quickly.

[vitalica]

Originally Posted by nsaidor

I still could not get all components as they seem not available here in Sri Lanka. I tried Farnel, esp. SST404 dual JFETs could not be found. Is there any suggestion for a replacement. Not sure how good the 2n3958 is?



vitalica,
Did you compare this with one of Krell clone KSA50 or Leach amp, if you have already built one of them?

Hi Nsaidor,

The Krell does not, but I compared Aleph5 and Leach, Holton.
Suzy's amplifier is my favorite
And my friends, they have made, are of the same opinion.
Every time you listen to are very surprised by the quality and transparency of sound!