Re: Cassette port input level

[mjmahon@aol.com (Michael J. Mahon)]

Simon Williams asked:

>I'm interested in running a variety of sound sources (guitar, mic,
>keyboard) through the cassette input of a IIe... is a standard line
>level output from a mixer safe for this purpose?

The cassette input has a 12K ohm impedance and requires a
level of 1 volt peak-to-peak.  If your line-level output can do that,
it should work fine.  (Many line-level outputs have impedances
on the order of 10K, so expect significant loading by the cassette
input--in this case, a voltage reduction of almost 2:1.)

If your amplifier has a headphone output, that would be perfect.

>I'm planning on writing some small ML routines to mess with the sound
>and fire it out through the speaker (with appropriately low
>expectations)... has anyone ese tried anything along these lines?

Yes--the first M/L I wrote for the Apple, in 1981!

Since the input is a zero-crossing detector, only one bit (the sign)
of the input signal is digitized, with two implications:  1) you can
pack the bits 8 to a byte and save a lot of space, and 2) the
resulting playback sounds like (and is) "infinitely clipped" or
"fuzzed",  so you know what to expect.

Ham radio operators often run their rigs with very high compression
levels, verging on infinite clipping (followed by bandwidth limitation),
so, with practice, you may find infinitely clipped speech fairly
intelligible, if not pleasant.  ;-)

-michael

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