Hi UDO/george, I’ve been having a debate on discord about the importance or unimportance of DACs on synthesizers. I know you need a general high quality of conversion but is it something that you thought much about in your design process of the S6? Or is it a case of DAC just changes digital to analogue, who cares?
minimaltom Don’t think you’ll get a reply on this one. You could look inside your Super 6, then look up the DAC chips online. There’s a photo of the inside that showed a number of identical voice cards. You can see orange LEDs on the voice cards through the vent slots, which seem to round robin as you play. Now people are buying the poly aftertouch conversion, more people will open up their Super 6.
The Super 6 is unusual as it has a DAC for each oscillator (and each modulator, but that’s another topic!). The DACs are simplistic and very nonlinear/ low fidelity. This doesn’t matter as the analog VCFs and to a lesser extent the VCAs smooth and colour the sound so much. The DACs for the digital effects are 24bit 192khz types designed for such an application and I just wanted them transparent and low noise. DAC and ADCs for music applications have got so good that even low cost ones blow those of a generation ago out of the water. However, they always can be better, but then many people like the “character” of some older CODECs. I still recon I can hear a 90s/00s Akai sampler signature for example but maybe my ears fool me.
Huh, that is neat. I figured most of the modulation would just stay in the digital realm, but I guess with the VCA and filter as mod destinations they need to be able to be analogue just in case.
Does every modulator always go through a D to A - even if it was say a digital lfo controlling the digital pitch of one of the DDSes?
Personally I’m not usually a fan of colored dacs, but the S6 sits in good company in my studio and I think it’s the best sounding synth I have ever owned, so I’m not going to question what’s in there. I would have guessed the dac might have to be some specialty design to deal with how high frequency the FPGAs are, something kinda like DSD. Or maybe something implemented on the FPGAs themselves since there are a few dedicated dac companies out there that use FPGAs to implement their own custom dacs (Chord Electronics jumps to mind, their stuff is as wildly expensive as it is wild).
Interesting that you call out the LPF as helping take some of the load off the dacs, my understanding is that’s where a lot of the research in trying to make dacs better goes whether it be Schiit with their multi-bit systems or Chord with their 1000+ tap filters in DSP. So just sidestepping that all with a musical LPF afterwards in the signal chain is a neat solution!