Hi. I found this headphone amp schematic on web. I simulated the circuit and there is a problem with output waveform. without dc feedback the amplifier output sits at couple of volts higher than ground. The output signal has fairly low distortion. But when I connect an integrator between output and input, the dc sums to zero as it should, but the output now has noticeable crossover distortion, at least it looks like that. Adjusting bias spreader does not seem to have any affect at all.

link to the schematic: http://www.audiodesignguide.com/Headphone_amp/headphoneamp.html





Can`t seem to figure out what is the cause of this problem...

 

Why is your integrator circuit significantly different from the reference schematic?

 

Yes it is... I tried a simpler circuit to see if that`s the problem. However I just double checked with the original integrator. The issue presists and the dc offset is worse than with the other integrator. UPDATE: made a mistake wiring the bias spreader. It works now!

 

You'll need almost twice the "normal" bias voltage, since you're using Darlington output pairs.

 

From what I see in this blurry pictures you made a mistake in the wiring a potentiometer. Yor 5k ohm's pot is short. Fix this and you should be able to set the quiescent current.
And here you have another version of a "Super Linear Circuit"
http://xen-audio.com/documents/SLHPA/SLHPA Description Public 171005.pdf