DAT recorder ADC and near to Nyquist frequency

[Martin Czech]

In the last discussion about room acoustic measurements the questions
arrised what pseudo random noise will do to ADC inputs, since it contains
a lot of hf energy.

I testet my Sony TCD D7 yesterday, with sine and sqare input.  Result:
from Fs/2=24kHz to about 40kHz there is noticeable alias!  But not all
is lost, maybe the speakers I plan to use will be quite dark, ie. high
frequency damped for F>12kHz or so.

But:

All people that record analog synths with digital stuff should be aware
of significant alias problems.  Note that problems are visible and audible
for a sqaure wave much lower than Fs/2. Best way would be to have a (balanced)
I/O module which eliminates everything > 18kHz or so.

LC notches?


m.c.