Solid Solid State Power Amplifier

[PMA]

Those interested in alternative output stages might consider the circuit I am attaching, but I am staying with 2EF output.

 

[AKSA]

I have considered something very like this OPS; Pavel, what are the advantages over the 2EF?

 

[forr]

Somewhat reminding Bryston output stage.
Needs matched beta of transistors Q5/Q7 and Q6/Q8, I think.

 

[AKSA]

Yes, very similar.... looks very good in simulation, with EC.

 

[PMA]

Hugh and Forr, it resembles Bryston output stage, but the circuit is different. Runs nice in simulation, but there are thermal issues and switch-off issues, cross-conduction very likely above 20kHz.

 

[PMA]

And the show's on again... PMA don't go again for another tour de vacation in the 'sunny bin'!..

Don't worry Michael, I have realized.

 

[PMA]

I use an amp, almost exactly like this, as my principal amp in my video system. It works well for this application!

This is very true, John. And not only for this application . I am very satisfied with the sonic result.

 

[john curl]

I once was friends with a fellow designer, who designed the Radford solid state amps in the 1970's. His output stage was very similar to the latest one provided here.
He was very sure that he could meet any challenge in audio, but I reminded him that his output stage used as many parts a my whole amp. ;-)

 

[Upupa Epops]

Look to the future, John, not only to the history...take idea: the best amp will come past us...

 

[AKSA]

Was that Arthur Bailey, John? Does this design look like the one?

Hugh

 

[PMA]

His output stage was very similar to the latest one provided here.
He was very sure that he could meet any challenge in audio, but I reminded him that his output stage used as many parts a my whole amp. ;-)

I showed it as an example, because I was asked here about different output stage than the 2EF. I do not use this last shown output stage. It has issues, as I have already mentioned. Switching off and crossconduction, and thermal stability.

 

[PMA]

Was that Arthur Bailey, John? Does this design look like the one?

Hugh

Similar problems.

 

[estman]

Hello Pavel, thanks for sharing and great example!
What makes dominant pole for NFB stability? Is it Cgs of M1 and M2?

I want to use 2sk213/2sj76 as M3,M4/M5,M6 and 2sk2013/2sj313 as
M1/M2. Can it be done without other changes and amp remains stable?

 

[PMA]

Hi estman - yes, mostly R5, R7 and M1,2 capacitances. You can run a simulation, or add some Cgd if necessary.

 

[sajti]

Hi,

one another idea for output stage.

Sajti

 

[PMA]

Hi Sajti,

have you tried it? The resistor values (22R) are reasonably low to handle switch off, it might work.

Anyway - how about thermal feedback, how is it solved?

Regards,

 

[sajti]

Not yet tested. I want to test it in this weekend.

Sajti

 

[juma]

Hi,

one another idea for output stage.

Sajti

Yes, the Lazy Cat's idea:
http://www.diyaudio.com/forums/solid-state/134789-balanced-igbt-amplifier-output.html

 

[sajti]

I found it somewhere on the net, about a year ago. I want to use it with tube preamplifier.

Sajti

 

[AKSA]

Sajti,

It has the great advantage of being very easy to drive, highly suited to a tube voltage amplifier. Band limited to overcome the cross conduction issue and overcooled, it might just be the cat's meow......

Hugh