Synth Engine External Interface

[Dave Strength]

Like someone mentioned below, I too am very impressed with the SID synth engine. I've been building analog synths for a while, and I came accross MIDIBox for the MBCV interface. After building it, I was interested in expanding the polyphonic functionality...and noticed comments in the ASM that eluded to making things more like the MBSID. After reviewing the SID I was blown away by the concept and implementation.

So I'd like to explore the options of adapting the MBSID engine to a complete analog synth. The concept here being able to not only take adavantage of the modulation subsystem...but also of the patching and overall synth management functions.

I realize there are quite a few external interface options allready present...but I'd like to have more flexibility and control over the synthesis portion..ie...some freedom from the SID chip will style enjoying the awesome MBSID engine.

Two possibilities come to mind. The first would be to develop a comm interface (perhaps PIC) to emulate the SID...essentially converting the SID control data back out to analog CV's and digital CMOS switches. This would have the advantage of being compatable with future MBSID releases...i.e leaving the original MBSID code unmodified.

The second, would be some modification of the MBSID itself to support more AOUTs and DOUTs to drive the analog synth.

Regardless of the method, the analog synth itself would be modeled after the internal SID block (or more precisely after the SID interface): 3 OSCs with TRI,SAW,SQR, and NOISE waves/ Pitch and PW CV, 3 VCAs with CV, 3 ADSRs with full CV, and Multimode Filter with Cutoff and Res CVs.

I searched the forums and didn't find anything similar...so I apologize in advance if this has allready been covered.

I'd greatly appreciate and input, ideas, or advice.

Thanks,

Dave Strength

[JRock]

Sounds Awesome :sorcerer:

[tokyomatik2]

ohhhhh

right now i just started my modular system and somewhere i still have a spare midibox core & Sid pcbs

this is definitively interesting

to be able to integrate the sid in a cv environment it's absolutely the next step to do

keep me updated about this project

cheers

[nebula]

A future project on my roadmap has been to do exactly this with the CEM3394 (synth-on-a-chip used in Sequential 6-trak series, Akai AX-60, Doepfer Dark Energy).

[Dave Strength]

The CEM reaplcement is another good idea...but that one's a bit easier since the original interface to that chip was in fact all analog. The SID is a bit different since it's interface is digital...an 8 bit data line and 4 bit address line.

I was really looking for some guidance from the programmers as to which approach might be best: the stand alone micro interface...or integrating into the current MDSID code. Perhaps even V3 accounts for this and a full external interface is allready planned? After all, sooner or later all the SIDs will be gone. I can't really find any now.

As far as the CV outs, I'm assuming we can use the existing MIOS functions for driving the AOUTs (NG's). The envelopes pose a bit of problem since they are CV intensive. For a true SID replacement...I'd probably just handle those digitally inside the micro and output one CV per VCA. So with three OSC Pitch and PW, Filter Freq and Res, and three VCAs, that's 11 CV's per SID interface. I'm curious how many AOUT's a single MBox core can drive? Is it 32?