By piecing bits and pieces together, and reading many sources I've come up with a design which seems to simulate ok. I was hoping to get any thoughts about it people may have, and improvements, or why it is so terrible before I purchase components to try it out.
The schematic can be found here
Cheers.
The schematic can be found here
Cheers.
You don't have any provision for adjusting the output stage bias. Why not replace R12 by a pot (say 220R).
Nothing is shown for trimming the offset.
You have no bias path at the input, so you absolutely require a DC coupled source, and must never power this up with the source disconnected.
You are running over 30mA through the LEDs, and I think that is a bit on the high side. You could replace R20 by either a higher value, or slip in a CC diode - say a J511, to get some extra PSRR.
No HF compensation is shown, and I don't think this is likely to be stable without it.
You might also want to consider putting emitter degeneration resistors into the input pairs, to bring the open loop gain down.
Nothing is shown for trimming the offset.
You have no bias path at the input, so you absolutely require a DC coupled source, and must never power this up with the source disconnected.
You are running over 30mA through the LEDs, and I think that is a bit on the high side. You could replace R20 by either a higher value, or slip in a CC diode - say a J511, to get some extra PSRR.
No HF compensation is shown, and I don't think this is likely to be stable without it.
You might also want to consider putting emitter degeneration resistors into the input pairs, to bring the open loop gain down.
A Classic pitfall circuit
the bias in the VAS is not firmly fixed by this circuit and may vary with component tolerance from simply nonfunctional to self-destructive extemes
http://www.diyaudio.com/forums/showthread.php?s=&threadid=16796
a possible solution:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=56860
but I usually dismiss the diff complementary front end as little more than "eye candy" having little advantage in audio amplification
many headphone amp designs are collected at
http://headwize.com/projects/index.htm
the bias in the VAS is not firmly fixed by this circuit and may vary with component tolerance from simply nonfunctional to self-destructive extemes
http://www.diyaudio.com/forums/showthread.php?s=&threadid=16796
a possible solution:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=56860
but I usually dismiss the diff complementary front end as little more than "eye candy" having little advantage in audio amplification
many headphone amp designs are collected at
http://headwize.com/projects/index.htm
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