<![CDATA[ChipMusic.org - Sid external input pin]]> 2016-02-23T23:13:23Z PunBB https://chipmusic.org/forums/topic/4443/sid-external-input-pin/ <![CDATA[Re: Sid external input pin]]> A few things to mention about the audio input pin:

  • If you want to work with this ext input pin, don't connect a signal directly! Instead, couple it with a 1-10 uF capacitor.

  • This pin is left floating in most (perhaps all?) C64 board revisions. It contributes to a huge amount of background noise and simply grounding it will give you a much better signal-to-noise ratio on your SID.

  • A switching jack can be used to automatically ground the pin when you unplug your input cable.

]]> https://chipmusic.org/jefftheworld 2016-02-23T23:13:23Z https://chipmusic.org/forums/post/240376/#p240376 <![CDATA[Re: Sid external input pin]]> What you can do with audio-in signals in the SID:
The EXT-In Signal is mixed with the internal sound voices and through the main volume register and through the filters.

So, when you just want to use the SID with the external audio signal you can adjust the volume and filter it.
Is has a setting for high-pass, low-pass, band-pass filter and combinations of it. has a register for the resonance frequency and a register to set the q-factor of the resonance.

but that all theoretical things are maybe a little bit useless when it comes to the old generation of SID-chips. theire filters behave very weired with lots of distortion. people used it in their way with the games that it sounded good with the "originally not intended" distortion of that filters.
also different SID-chips from the same production behaved different cause of the production process that delivered not constant results for the analog parts on the chip.

so these filters are not something that made the c64 great for modifying external audio signals.
however, when you have the later models of the SID: 8580/6582 or 6581R4AR the filters work good and predictable - like the designer wanted them to behave at the first place (but did not have the time to correct it that way cause the c64 needed to be finished and sold!).

but is the SID-chip a worthy chip just for filters with a digital interface? i don't know the chips that are available for filtering, but i guess there are good chips available for that kind of task. i don't know about the ealy 80's - anyone?

]]> https://chipmusic.org/WhyLee 2016-02-23T13:37:01Z https://chipmusic.org/forums/post/240333/#p240333 <![CDATA[Re: Sid external input pin]]> that is pretty sweet.

]]> https://chipmusic.org/wedanced 2011-07-13T06:58:35Z https://chipmusic.org/forums/post/73262/#p73262 <![CDATA[Re: Sid external input pin]]>

Then there is this  ;-)

]]> https://chipmusic.org/cTrix 2011-07-12T17:01:23Z https://chipmusic.org/forums/post/73172/#p73172 <![CDATA[Re: Sid external input pin]]> yaaahh the famous vicious sid demo. do you know if the source code of the routine is available anywhere?

bw don't forget to check the best part of that demo: http://www.youtube.com/watch?v=ZW2XKSWUPLw

]]> https://chipmusic.org/irrlichtproject 2011-07-09T22:55:47Z https://chipmusic.org/forums/post/72751/#p72751 <![CDATA[Re: Sid external input pin]]> if you're a kickass coder you can use the filters with samples anyway

]]> https://chipmusic.org/4mat 2011-07-04T21:38:08Z https://chipmusic.org/forums/post/72179/#p72179 <![CDATA[Re: Sid external input pin]]> Also: you could fry the chip plugging shit in so I never bothered with it.

]]> https://chipmusic.org/akira%5E8GB 2011-07-04T13:49:05Z https://chipmusic.org/forums/post/72135/#p72135 <![CDATA[Re: Sid external input pin]]> Of course, but I've never really seen a need to have an audio in on the C64.

]]> https://chipmusic.org/InactiveX 2011-07-03T23:58:21Z https://chipmusic.org/forums/post/72094/#p72094 <![CDATA[Re: Sid external input pin]]> Couldn't you attach it to a switching 1/4" jack that grounds the pin when nothing is plugged in?

]]> https://chipmusic.org/kineticturtle 2011-07-03T20:02:09Z https://chipmusic.org/forums/post/72077/#p72077 <![CDATA[Re: Sid external input pin]]> wedanced wrote:

.... have any of you tried to do something with this guy? its pin 26.

I usually ground it, as it is floating as standard on a C64. Grounding it reduces noise, although it prevents the audio input from being used.

]]> https://chipmusic.org/InactiveX 2011-07-03T17:55:41Z https://chipmusic.org/forums/post/72070/#p72070 <![CDATA[Re: Sid external input pin]]> apparently i am behind the times. Is I mean.... have any of u guys used the sid filter as an efx processor? How does it sound?

]]> https://chipmusic.org/wedanced 2011-06-14T21:08:21Z https://chipmusic.org/forums/post/70282/#p70282 <![CDATA[Re: Sid external input pin]]> Is there any sid based synth that doesn't use it?

]]> https://chipmusic.org/nordloef 2011-06-14T19:10:16Z https://chipmusic.org/forums/post/70275/#p70275 <![CDATA[Re: Sid external input pin]]> It runs the external input through the SID filters.

]]> https://chipmusic.org/akira%5E8GB 2011-06-14T15:35:49Z https://chipmusic.org/forums/post/70260/#p70260 <![CDATA[Re: Sid external input pin]]> prohphet64 mssiah uses it. So does hardsid big_smile

]]> https://chipmusic.org/herr_prof 2011-06-14T14:04:14Z https://chipmusic.org/forums/post/70258/#p70258 <![CDATA[Re: Sid external input pin]]> AFAIK it is just used for filtering.  So I might be wrong but whenever there is an instance of filtering in anything on the C64 if you pump audio through that it will be filtered.  Lots of people do it wither their MSSIAH setups and stuff.

]]> https://chipmusic.org/Theta_Frost 2011-06-14T00:46:26Z https://chipmusic.org/forums/post/70226/#p70226