[Arm-netbook] goodbye LM13700, hello CM108AH

[Derek]

luke.leighton <luke.leighton <at> gmail.com> writes:

> 
> it is with much sadness and regret that for parts in the flying
> squirrel i say goodbye to the LM13700M, a part with a huge and rich
> history, having seen its first emergence into the world around 1967
> even predating the moon landing.  the reason is simple: the bias for
> the diodes is 3x 0.7 volts and on rails of +/-2.5V it's simply not
> enough.  i'm seeing silence at low volumes... and then huge clipping.
> i simply don't have time to resolve this.

For those of us with electronics experience but maybe not name recognition
of ICs: the LM13700M is a dual op-amp, which Luke may be trying to configure
as a Class B amplifier (push-pull).  Since his input voltage is so slight,
the circuit is spending too much time in cutoff, except where it reaches
saturation.

Luke, using a class B amp is going to result in crossover distortion.  I
think that's what you're seeing.  So, you're replacing your homebrew power
amp with a C-Media USB Audio device?  Is this directly connected to the USB
lines, or after a hub?

Derek