Arfa Daily wrote in message
...

"N_Cook" wrote in message
...
Assuming my test tape is stretched (I doubt it , as it would have to be
even
stretch the whole length).
I normally test speed monaurally so the beats are unmistakable. That is
1KHz
test tape output and floating accurate 1KHz sine signal both fed into
one
headphone cup. Easily gives 0.1 percent resolution (assuming test tape
is
ok).

If I record accurate 1KHz tone onto a blank tape for exactly ( to human
reaction time accuracy) 100 seconds. Then replay for beats of 1Hz or so
and
output lasts for 100 seconds +/- reaction time then is the speed
correct?
I
suspect that repeating this process with the speed regulator changed ,
say
5
percent, would also give "correct" speed, that time also


Does anyone know how much effect types and thickness (play duration C30
to
C90) have on replay speed perhaps in conjunction with too soft or too
hard
pinch wheel rubber ?



I just use a speed test tape from Konig. It has a strobe wheel behind what
would normally be the tape viewing window. Very easy to see an accurate
setting for the speed, and virtually instant comparison between forward
and
reverse. Also easy to see any cyclic variations in speed, or long term
drift.

Arfa




Strobing of what rotational part against what reference?
How do you know if the tape is stretched?