Forum64

spät aber doch, antwort findet sich im programmers reference:

EXT IN (Pin 26)

This analog input allows external audio signals to be mixed with the
audio output of SID or processed through the Filter. Typical sources in-
clude voice, guitar, and organ. The input impedance of this pin is on the
order of 100 kohms. Any signal applied directly to the pin should ride at
a DC level of 6 volts and should not exceed 3 volts p-p. In order to pre-
vent any interference caused by DC level differences, external signals
should be AC-coupled to EXT IN by an electrolytic capacitor in the 1-10
uF range. As the direct audio path (FILTEX=0) has unity gain, EXT IN can
be used to mix outputs of many SID chips by daisy-chaining. The number of
chips that can be chained in this manner is determined by the amount of
noise and distortion allowable at the final output. Note that the output
Volume control will affect not only the three SID voices, but also any
external inputs.


also die 100k sind zwecks impedanz und der cap ist ein koppelkondensator, wenn der sid länger halten soll würde ich das so übernehmen. das eingangssignal sollte so wie im linken schaltbild auf kondensator und widerstand gehen, in der schaltung ist das eben als klinkenbuchse gezeichnet.