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Rub_0201
Registered: Apr 2019
Posts: 13 |
How to mute the voices of the SID?
Hi!
I want to remix my favorite SID tunes. A lot of them have nice rhythm, ideas and melody, but if I hear them more then 10 times in a loop, I get dizzy.
I want to bring more stillness and a different temper in them - making a remix.
My idea is to mute one or two of the voices of the SID and additionally fiddle around with some registers.
I did that with emulators like the C64debugger("24Hours Demo Remix" on YT) and the result is quite nice. Now I want to do it on the C64 itself.
As I am no SID programmer or musician, I have no clue how to do it on the real machine.
I understand fundamental assembly coding, but I am far from doing fancy stuff.
So I need your help! |
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Rub_0201
Registered: Apr 2019
Posts: 13 |
Ahh, now it makes klick ;-)
Good to know, @Mixer, the klicks in that instrument are not intended and they apear also with all voices playing. |
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Hoogo
Registered: Jun 2002
Posts: 105 |
Is it common that players access SID registers only once each call? If there were more, then the first access would be lost. |
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chatGPZ
Registered: Dec 2001
Posts: 11324 |
Most "modern" players do. However, lots of old players write them more than once - or even read them |
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spider-j
Registered: Oct 2004
Posts: 494 |
Quoting MixerClicks and snaps are part of SID music :)
After looking at the actual filter programs I'm pretty sure that the author just had either a completely special 6581 or no real 6581 at all and the old emulation at the time of GT1 was misleading.
Turning on / off filters on one voice in such a manner is something you can only do safely on a 8580.
I know, 6581 fans don't like to hear it, but the 6581 was just "broken" (volume/filter switch clicking, mixed waveforms not working, unpredictable filter curves, etc.) and the 8580 is the way the engineers wanted the SID chip to be. |
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chatGPZ
Registered: Dec 2001
Posts: 11324 |
Quote:mixed waveforms not working
They don't work (as intended, or even as documented) on the 8580 either - that they produce a "better" audible result on 8580 is purely a side effect of the different manufacturing process (there is no "fix" for this in the 8580) :) |
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spider-j
Registered: Oct 2004
Posts: 494 |
Quoting chatGPZof the different manufacturing process (there is no "fix" for this in the 8580) :)
Well at least the manufactoring process seems to have been optimized (?) in a way that you get comparable results between chips – I'd also let this count as kind of a "fix" :-) |
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Bansai
Registered: Feb 2023
Posts: 46 |
Quote: Clicks and snaps are part of SID music :) You may also notice differences due to the ring and sync modulated sounds. They need the other sid voice oscillator active, using correct waveform and frequency. In that case you may have to use some other method to mute the channel. Perhaps ADSR to 0 or the filter as aeeben mentioned.
Sometimes it's helpful bringing up the scope display on DeepSID to see what's going on, or record to a wav file and bring it up in Audacity.
ADSR=0 in isolation should still cause some undesired noise on gate 0->1 because there will be that 2ms attack to 15 even though the sustain volume is zero. This is part of what makes using sustain as a per-voice volume control a bit of a tricky proposition because if you ever store, for example, pulse $40 then $41 back-to-back in order to get a new sustain in the envelope generator, you'll see that momentary spike in the waveform as a quick, little triangular hat. It's very obvious for noise waveform. If you just do it once when muted and AND the target waveform with #$FE, sustain=0 should work fine unless there is some kind of oscillator leakage. Doesn't that exist where some oscillators can be heard quite faintly on some chips even when they're completely gated off?
Perhaps the only reliable way one could mute a voice because of cross-voice features like ring modulation and hard sync is at a point downstream past all the digital calculations.
If you're running this in an emulator for your own personal use such as during song development, it doesn't matter. You could just throw a register decode out there at $d41d-$d41f that does what you want.
But yeah, those clicks and snaps. :-) |
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Rub_0201
Registered: Apr 2019
Posts: 13 |
Banzai,
DeepSID is amazing. Did not know about it.
Checked a lot of buttons - did not find a scope view though.
The unwanted clicks are gone now! Went to more SIDs and Rob Hubbard plays great - project is going well :-) |
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Bansai
Registered: Feb 2023
Posts: 46 |
Quote: Banzai,
DeepSID is amazing. Did not know about it.
Checked a lot of buttons - did not find a scope view though.
The unwanted clicks are gone now! Went to more SIDs and Rob Hubbard plays great - project is going well :-)
JCH and others did a great job with that site.
There should be a tab for the scope
News / Tags / Scope / Filter / Stereo
It's not available for all players, but it should work for the regular WebSid one (not legacy).
Volume is also shown if you scroll down once waves are up, so for the usual $D418 digis, you can see them as well. |
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Rub_0201
Registered: Apr 2019
Posts: 13 |
Thanks bansai. Found the buttons. They're on the left. |
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