Commodore Remix

Thanx for the comment Vosla

well... I've been making a function to inverse the filter envelope (specially handy with the Hipass filter)... but other than that not much has been coded today... Here's a small demo of how the ADSR filter envelope works now... slow attack with large distances between notes, but when playing quick'er, it shortens... much more playable this way.

Everything used is SID, only the Kick is not...

http://razmo.ziphoid.com/Tech.mp3

Not only, you are making a cool piece of hardware, the demo's also sound cool. I like this Tech one. would love to hear a complete song made of this sequence But that would take away from building the hardware

Analog-X64 wrote:Not only, you are making a cool piece of hardware, the demo's also sound cool. I like this Tech one. would love to hear a complete song made of this sequence But that would take away from building the hardware

Thank you ANX ... and you're perfectly right... making music takes the time from coding the synth ... also I'm not in music making mode at the time... I've not been coding for years, and I missed it a lot, so I've dedicated my time to this for some time now, and I intend on building for as long as the urge is there... especially with me, this is important

Anyway, it's beginning to have the feel of a synth now... which is also why I get inspired to make some short demo's here and there... there is still a lot to code though, especially pitch and pulsewidth modulation routines, but I'm still finetuning the envelopes for the volume and filter... found a little bug in the envelopes yesterday, and I want a switch for changing between hard and soft reseting of the envelopes (so you can choose if they should restart from where they left off, or reset to zero).

I also have to remove a few unnecessary features from the volume envelope, as inversing this envelope and having seperate legato funktion for both filter and volume is not necessary... the whole point of the Micro SID was to make a SID synth that is powerful, but not too complicated to program... this means that every LFO, ENVELOPE or other modulation source will be hardwired to specific parameters... no modulation matrix will be present.

At current I want:

1 Envelope each for Filter, Volume, Pitch 1-2-3 and Pulsewidth 1-2-3
1 LFO each for Filter, Volume, Pitch 1-2-3 and Pulsewidth 1-2-3

That's 8 envelopes, and 8 LFOs

I've not yet decided how to implement wavetable modulation, but it'll be there of course... most likely an 8-step type for all three voices... anyways I'll have to economize with the available patch memory, as I decided to go with 126 bytes of patch data structure.

The reason for the 126 and not the more likely 128 is that MIDI is only 7bit wide in it's data bytes... so to send 8bit bytes you create small packages of 8 bytes containing 1 byte of seven most significant bits and 7 bytes of the 7 lower bits... thus the number of bytes in a patch dump must be dividable by 7... and 126 is closest to 128 bytes.... you could send a last package with 5 dummy bytes in it, but I don't want to make the ekstra code untill I know if it'll be necessary.

UPDATE...

I've recieved some digital potmeters from Microchip, and have now full digital control of the feedback amount from the microprocessor... I got some dual digital pots, so that I can control both feedback and the volume of the audio output of SID... the later will allow me to circumvent the ADSR bug of SID at last, giving me 256 niveaus instead of SID's 16 niveaus only.

Actually I had thought I would have to spend days finding hardware and communication bugs with this pot chip, but everything seemed to work in just under an hour without any hardware problems at all... a bit proud of this actually

I also coded an LFO for the Filter... currently I can control LFO Shape, Rate, Depth, Phase and Delay (with fade in)...

Here is a demo of the feedback in action... starts out without feedback... be careful with your speakers, as this is ridiculously selfoscillating resonance coming from SID in a way you have maybe not heard before ... LFO is also active on the filter.

http://razmo.ziphoid.com/FeedbackSID2.mp3

Nice, reminds me of old sci-fi movies.

NEW UPDATE...

http://razmo.ziphoid.com/VibratoTest.mp3

I've not been working on the project for some time (nice to get a little break from it)... I've now started coding again, and the link above demoes a new Vibrato LFO for one of the SID's 3 oscillators. The demo start out with two sawtooths in phase, and an underlying pulse waveform on the third oscillator (one octave deeper, and free running).

It start out without any vibrato, and then I introduce vibrato on one of the sawtooth oscillators (up to one semitone)... the demo ends with the LFO rate being tweaked a little.

More updates when I have something new...