OPA627 as input stage? Output can be BJTs..

[rhythmsandy]

I have seen somebody talking about this schematic where the input is handled by OPA627 and output is some pushpull stage... is it really possible to use opa627.. some say this chip is better than many discrete designs which I dont believe tough. But Is it really possible to use this as input stage?

 

[jcx]

for what?

mm phono pre amp

line driver/headphone amp

audio power amp

I'd guess you could find examples of each - simple enough to put your choice op amp in front of a chip amp in a multi-loop for power

 

[tvrgeek]

Yes possible. Yes it is very clean. IPS is a current amplifier and must operate at voltages compatible with the VAS. That makes a chip op-amp not always a great IPS.

 

[rhythmsandy]

how is it possible is there any schematic?
btw how is it possible I believe AD815 can do the job. Are you talking about the Voltage source or voltage output / current output?

as a current amplifier how many milli amps do we require? to drive a 2k1943

 

[jcx]

diff pair, even VAS usually don't drive single push-pull transistor pair output stages at high power, or current either so why would you expect "op amp as front end" to have to

dual, triple followers, or CFA are pretty standard in BJT power amp output stages, most competent designers recognize even MOSFET output require drivers to handle output Q gate dynamic currents

 

[nalimko33]

OPA627 & LYNX
http://audio-circuit.dk/images/LYNX-v3-0-QAG.pdf

 

[rhythmsandy]

did anybody auditioned this?

 

[rhythmsandy]

since its pretty good opamp that should be sounding good. Any reasons why cant one use them?
IMD would be high but how about the sound quality altogether?

 

[Boscoe]

An op amp has very low distortion easy and air current drive why not use it as an IPS?

Because its easy and people can't understand why something easier could be better, peoples pre conceptions make things sound different not the equipment. Most of the time.

 

[rhythmsandy]

i think the above schematic doesnt even need a preamp section...

 

[juma]

This is simple and sounds nice (especially if Laterals are class A biased - R8 value sets Iq). Power is limited by OpAmp's PS voltage - I measured a bit less than 15W_peak at 8 Ohms.

 

[rhythmsandy]

where can i buy that module?

 

[rhythmsandy]

how is the sound quality compared with any other discrete designs? since this amp has very low distortion figures and also a good opa.
Did anybody built this?

 

[OnAudio]

You might be interested http://www.diyaudio.com/forums/solid-state/207746-hal-opb-amplifier-2.html

 

[rhythmsandy]

lynx seems interesting and Im very interested to see that delivering more power..

 

[tvrgeek]

Plus and minus 15 V does not work very well with 35V rails and VAS. Cap couple?
A very good IPS is not hard. Don't work too hard trying to find a shortcut.

 

[rhythmsandy]

why cant be two opa627 get bridged?

 

[rhythmsandy]

Its not about shortcut well there was Jeffrowland coherence which is said to be one of the best preamps in the world using AD815 with battery psu... finally it should be good..

 

[jcx]

op amps can be used in floating supply power amps to 100s of W

Crown, QSC, Behringer all make cheap PA with this topology

http://www.diyaudio.com/forums/soli...o-floating-supply-amplifiers.html#post2202342

http://www.diyaudio.com/forums/solid-state/200572-inverted-not-inverting-output-stage.html

http://www.diyaudio.com/forums/solid-state/101602-qsc-clones-backwards-amps.html#post1204834