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How to connect SID audio out


Guest eirik_k

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Guest eirik_k

Hi. I have now uploaded the software in my (as of yet) minimal MbSID setup, and I'm ready to give it a virgin jam session.  ;D

I'm sure it is a simple enough question to answer, but how do I connect the audio out?

The 1/4" jack socket has two connectors, the audio cable has an inner and an outer wire, but the SID unit has one audio out and one pin that's supposed to be grounded.

Do i connect only the one out pin to one pole on the jack plug, if so, which one, the tip or the inner part? Do I connect the other one to the power unit ground, or should it be metal chassis shielded?

I'm sure there's some basic consept I've missed, but then again, I am kind of an electronics newbie.   ;)

I manage to get a low, low, low, low, low signal with either configuration when I crank the gain waay up on my mixer, but that won't do.

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The audio out pin on your SID module should connect to the tip contact of your 1/4" jack socket, and the grounded pin on the module should connect to the sleeve contact of the jack socket. I suppose your SID to mixer cable is all right - tip connects to tip, sleeve to sleeve?

It's fun to hear someone is just about to get his MBSID on the road - I'm still waiting for my parts orders to arrive to begin building my dual SID machine...  ;)

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Guest eirik_k

Success! It seems the audio cable from SID module to jack socket was bad somehow, I tried a couple of common connection cables instead and it works much better.  :-[

But alas, not quite as it should. After the test tone, I get a constant high (c 5-ish) tone, and the when I play, there is heavy interference from the constant tone. After a note, the constant tone is back but sort of frequency modulated . It seems voices 2 and 3 are responsible. Turning them off does not work but changes the constant tone character. If I route them to the filter and turn off all filter modes, the tone stops and I am left with a working voice 1. Minus filter. Not terribly exciting.

So I seem to have a broken SID, don't I? (actually, two broken SIDs) Or could this problem be a symptom of something else?

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Guest eirik_k

No, I have a single SID and core module using the setup in http://www.ucapps.de/mbhp/mbhp_sid_c64_psu.pdf with an original C64 PSU. My SID gets 5.08V and 11.87V from pins 8 and 28, respectively.

Really, it does sound like voices 2 and 3 are simply broken, they are constantly gated, do not follow input pitch but rather are modulated by voice 1, and their waveforms are all wrong.

I'll just have to get another C64 or SID (both most likely) to be certain. Oh well...

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