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Synthesis Techniques For Emulating Vintage Sounds

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Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Mon Jul 27, 2020 10:29 am
by ramthelinefeed
N i g e l wrote:Non - VCO synths with static pitch offsets:

The WASP synth uses a master oscillator which is frequency divided down to produce the note frequency (controlled by a note_number & octave number).
The division is only 8 bit, so the note pitches are not exact.

This is similar to organ technology of the time where note pitches were derived from a master oscillator & a top octave divider IC. This was also used in String Synths and also I think some monosynths too.

I dont know the accuracy of the organ chips in terms of pitch.

That's very interesting, cos I think the synth I own which exhibits this effect most is a Yamaha CS01, which if I recall correctly from the Service Manual, also uses a digital divide-down from a master VCO running in MHz.

Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Mon Jul 27, 2020 12:57 pm
by N i g e l
My Wasp is actually a Jasper; schematics available here :

http://www.jaspersynth.co.uk/wp-content ... ematic.pdf
Top Oscillators are 555 timers, dont know the frequency.

The Jen SX1000 uses an M110 chip which looks to incorporate a keyboard scanner & dividers.
Schematics & MIDIfication projects are available online somewhere


ORGAN chip databook:

http://www.bitsavers.org/components/sgs ... OS_2ed.pdf

Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Tue Jul 28, 2020 7:05 pm
by Dashanna
N i g e l wrote:
[2] modulate the note with the midi note number. Same "error" for a particular note but obviously as the MIDI note number increases the error increases.

Yes! This trick seems to me the most effective for me on my E-mu P2K module. A tiny bit of note number added to the fine pitch, to simulate a not quite accurate range and scale. Especially if added differently to two oscillators (or just to one) meaning that each note will have a consistently different detune character.

On something like the Nord Modular I still use, it is possible to set a sequencer to cycle through a different set of pitch and filter variations on each note - to simulate, for example, an Oberheim poly-synth cycling through voice cards.

But, you could get too caught up in where all this instability is supposedly coming from - really, just a bit of randomness from whatever sources are available is sufficient.

Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Tue Jul 28, 2020 7:14 pm
by desmond
Dashanna wrote:But, you could get too caught up in where all this instability is supposedly coming from - really, just a bit of randomness from whatever sources are available is sufficient.

Yep - which was the point I was making.

Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Tue Jul 28, 2020 8:52 pm
by ramthelinefeed
desmond wrote:
Dashanna wrote:But, you could get too caught up in where all this instability is supposedly coming from - really, just a bit of randomness from whatever sources are available is sufficient.

Yep - which was the point I was making.

Yes but your point was wrong because this thread is about something which ISN'T random :headbang:

Re: Synthesis Techniques For Emulating Vintage Sounds

PostPosted: Tue Jul 28, 2020 11:09 pm
by N i g e l
Dashanna wrote:
On something like the Nord Modular I still use, it is possible to set a sequencer to cycle through a different set of pitch and filter variations on each note - to simulate, for example, an Oberheim poly-synth cycling through voice cards.

Awesome, id never thought about doing that !