[sdiy] Headphone distribution amp

[Magnus Danielson]

From: harry <harrybissell at prodigy.net>
Subject: Re: [sdiy] Headphone distribution amp
Date: Fri, 06 Apr 2001 16:55:27 -0500

> Hi Magnus...

Hi Harry,

> OTOH:  If you have a circuit based around most op-amps... it will not
> matter
> if the supply voltages are matched or tracking. Most important is
> probably just
> ripple rejection. Even the 78XX / 79XX is probably just fine.

Certainly, the actual voltage levels is not THAT sensitive, but
things like ripple damping becomes important since you want the
voltage to be quite in the frequency range where you one way or
another hook it into the audio/processing path.

Also, the PSRR of chips is also of interest, but for PSRR to be a
critical parameter you need a poluted powerline to start with, and
cleaning the line from the PSU side and not spread excessive signals
along the power lines are the recommended things to do. Just
decoupling noise-makers is one thing to do.

Don't forget to short large caps (say >10 mF) with a small plastic cap of say
around 1-100 nF or something directly over the terminals. This way
will let spikes pass by the cap without riscing to reverse
polarity. Cheap insurance...

> Any of the above will exceed BBD quality standards..   (as would
> dissimilar metals stuck into a few lemons....)

Sure will! ;)

> >H^)   harry (horns by request !)

Ah, thanks! ;)

Cheers,
Magnus