April 2017 63
of harmonics — predominantly odd-harmonics.
The clipping is more aggressive at
the extremes of signal input; almost
an “all or nothing” affair. Contrast
that to the tube clipping, which is
more like “diminishing returns.” I have
heard of an amplifier circuit that adds
even-harmonic components of the
signal. I haven’t built it, but the idea is
that it would create a warmer sound.
Having said all that, clipping
and harmonic content (warm versus
cool) should not be thought of as
synonymous. Clipping occurs at
the extreme limits of signal input.
Nonlinear transfer curves can create
harmonics at any value of input signal.
When you look in the mirror in the
morning, you are seeing a “linear”
reflection of yourself. At the carnival
or fairground when you stand in
front of curved mirrors that distort
your reflection, you are seeing an
exaggerated “nonlinear” reflection
of yourself. While seeing such
exaggerated nonlinearity is humorous,
in the audio realm it would be
intolerable to listen to ... maybe.
Guitar effects pedals intentionally
distort the signal, sometimes to an
extreme that is almost unrecognizable
— but, that’s an article for another
[#12162 - December 2016]
Does anyone have a simple circuit
that will allow me to mix my iPod
audio out with my computer’s audio
to play through the same speakers? I
want to avoid un-plugging/re-plugging
just to hear some music.
I use a simple DPDT toggle
switch for something like this. I switch
my computer output between the
speaker and headphones without
wearing out the headphone jack.
In your case, the audio to the
speaker would be switched between
the iPod or the computer. The
speakers must be amplified, and the
computer’s output volume adjusted
down to be close to the level coming
out of the iPod headphone jack. You
can mount the jack and switch on the
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