[Dtb-talk] A question about preferred book formatting

[Flint Million]

Guys,

An FFT algorithm could detect the tone indexes. I'm not exactly
experienced enough with programming to attempt such a feat myself, but
with time and practice I probably could punch out a tone-index
detector. FFT is the same algorithm that would be used to remove that
rumble from the final recording, because you could do a high-pass
filter to eliminate the low frequencies. If you were spinning a tape
at about 30ips and measured a tone index tone to be about 600 hertz,
at 15/16ips you'd have a tone of about 20 hertz, right at the bottom
or below the hearing range of most people. What you her in the rumble
is the distortion of the waveform as the tone pushes the wave towards
the edges of the spectrum. A highpass filter blocking frequencies
below, say, 50hz is more than enough to filter it out.

FM