Take 5 oscillator sync

Take 5 oscillator sync
« on: January 03, 2023, 04:18:13 AM »
Hi guys! My question is about Take 5 oscillator sync. I donít understand why it works in a very different way compared to other analog synths.

I've owned many synths like the Moog Little Phatty, Subsequent 37, Bass station ii, Korg Minilogue, and Monologue, and Osc Sync works in a similar way on all of them.  For example,choosing for both Osc1 and Osc2 the sawtooth wave , the same octave and press to sync.  As a result, the sound changes very little adding some new harmonics probably,  and it sounds louder and fatter. 

In comparison, doing the same thing on Take 5 it cancels the frequencies, producing a thin sound, going up an octave at times whatever you do with the pitch of the OSC1. ( I use it in unison mode and 1 voice only to simulate a monophonic synth).  I've tried it with different waveforms, sawtooth, square, pulse, etc. (always using the same one for both oscillators) Take 5 is the only instrument I've had that produces cancellation in this case. I have the latest beta firmware installed on the Take 5

Re: Take 5 oscillator sync
« Reply #1 on: January 03, 2023, 08:20:48 AM »
Hi guys! My question is about Take 5 oscillator sync. I donít understand why it works in a very different way compared to other analog synths.

I've owned many synths like the Moog Little Phatty, Subsequent 37, Bass station ii, Korg Minilogue, and Monologue, and Osc Sync works in a similar way on all of them.  For example,choosing for both Osc1 and Osc2 the sawtooth wave , the same octave and press to sync.  As a result, the sound changes very little adding some new harmonics probably,  and it sounds louder and fatter. 

In comparison, doing the same thing on Take 5 it cancels the frequencies, producing a thin sound, going up an octave at times whatever you do with the pitch of the OSC1. ( I use it in unison mode and 1 voice only to simulate a monophonic synth).  I've tried it with different waveforms, sawtooth, square, pulse, etc. (always using the same one for both oscillators) Take 5 is the only instrument I've had that produces cancellation in this case. I have the latest beta firmware installed on the Take 5

This sounds quite like how the Prophet 6 handles sync, too. Odd and something I've never quite gotten used to.

kpatz

Re: Take 5 oscillator sync
« Reply #2 on: January 04, 2023, 04:35:16 PM »
Mine does the same thing.  Interestingly if I change the oscillators to a narrower pulse it doesn't seem to happen.  Though, if I sync 2 saw waves at the same pitch, it gives the effect of a saw 1 octave up.

My guess is it's related to how the sync works in terms of whether it's syncing to the leading or trailing edge of the waveform, or there could be a phase delay in the sync circuit.

To provide an example, take two oscillators producing square waves.  The waveform alternates between "high" and "low".  Let's say the oscillator resets to the beginning of the "high" of the square when it receives a sync signal.  If the sync responds to the 2nd oscillator transitioning to the "high" of its square, the two oscillators will sync in phase, as the synced oscillator will start the "high" phase of its square when the master oscillator has done the same.  If the sync responds to the transition to the "low" instead, then the oscillators will sync out of phase as the slave will start the "high" cycle when the master starts the "low".

Based on my observations, what I think may be happening in the Take 5 is the sync source is the square/pulse wave output of Osc2 and the Osc1 resets on the 2nd half of the wave from Osc2, leaving the two oscillators 180 degrees out of phase when synced.  This would lead to phase cancellation of a square or sine wave and the "octave doubling" effect on the sawtooth.

It's a design decision, or possibly in the case of the Take 5, a characteristic of the SSI2130 VCO chips and how they respond to sync, and which waveform output Sequential chose to use as the sync source from Osc2.

The OB-6 doesn't do this... its sync puts the VCOs in phase.

« Last Edit: January 04, 2023, 04:40:01 PM by kpatz »

Re: Take 5 oscillator sync
« Reply #3 on: January 04, 2023, 04:57:34 PM »
It would be worth emailing sequential support to ask. Perhaps it is something that could be addressed in firmware.