Opamp front end examples

[jaycee]

Hi,

Just bored and pondering over power amps that use opamps in their front end instead of a discrete LTP. Anyone got any links to schematics of other amps like this?

So far, i've looked at the MF B1 and the Arcam DiVA A90 amplifier.

 

[RSK]

OPA134 front end

Try white noise audio. I have the MOS125 circuits and they sound good.

Cheers,

RSK.

 

[latala]

try also bgw /amcron/ phase linear /musical fidelity
thee are loads of them out there!
regards trev

 

[ash_dac]

Hi,

Just bored and pondering over power amps that use opamps in their front end instead of a discrete LTP. Anyone got any links to schematics of other amps like this?

So far, i've looked at the MF B1 and the Arcam DiVA A90 amplifier.

Rega Brio thread. But you posted on that thread

http://www.diyaudio.com/forums/showthread.php?s=&threadid=54448&highlight=

 

[Lenin]

Musical Fidelity Worth a look...

Mmmmm.....

Look at the MF schematics (particularly for the P170, P270, P370, P470). The DO use a LM318 op-amp front ends, but the internal long-tailed pair is disabled, allowing the use of an all discrete version.

Errrr... I guess that is kinda the exact reverse of what you are after (semi-discrete rather than op-amp only front end) but worth a look...

By the way, no-one on this forum has yet been able to work out how to utilise other opamps in that particular MF topology. (Much to my frustration........!)

 

[AndrewT]

Hi,
the British J.E.Sugden P128 uses 5534 as a times 2 gain stage at the front end. It is outside the global NFB.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=93687&highlight=

 

[jcx]

http://www.qscaudio.com/support/library/schems/Current/RMX Series/rmx850.pdf

ne5532 and floating ouput supplies

 

[scott wurcer]

The Sumo-9 used two LF353's in the in-amp configuration. Kind of a cute circuit, and the patent's expired.

 

[AKN]

hi,

Lets not forget Jan Dupont and his "LYNX" poweramp.
http://www.audio-circuit.dk/LYNX_main.html
Further developed into PA-34 II
http://www.delta-audio.com/PA-34A.htm

 

[sixtek]

hi,

Lets not forget Jan Dupont and his "LYNX" poweramp.
http://www.audio-circuit.dk/LYNX_main.html
Further developed into PA-34 II
http://www.delta-audio.com/PA-34A.htm

Hmmm... These are reminding me the Phase Linear model 300.
The same circuit with modern devices.

 

[AKN]

Hi sixtek,

Hmmm... These are reminding me the Phase Linear model 300.

Yes, very much so. One driver stage added.

 

[danville]

The Sumo-9 used two LF353's in the in-amp configuration. Kind of a cute circuit, and the patent's expired.

I have looked at the Sumo circuit. It doesn't look all that special. What was the patented feature?

 

[jacco vermeulen]

The bias regulation (1980 patent)

 

[Jan Dupont]

Lets not forget Jan Dupont and his "LYNX" poweramp.
http://www.audio-circuit.dk/LYNX_main.html
Further developed into PA-34 II
http://www.delta-audio.com/PA-34A.htm

Hmmm... These are reminding me the Phase Linear model 300.
The same circuit with modern devices.

Yes this is "as stated" an "old type" of amp, however if you want dynamic power, this amp kills all never < $800 amps

And yes it a hybrid between old GAS, Phase Linear and Amcron/Crown amplifiers, which was (and still are many places) the selected power amp in many studios etc.....

I agree that many "newer" amps has better measurrements, however for me it the sound that decide my choice of amp