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Sequencing an SQC Pro One with x0xb0x or TB303
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Sequencing an SQC Pro One with x0xb0x or TB303
Hi it's been years that i have a pro one and sequencing it with Roland gear it never worked as it should. I tried with a gate 5V and 11.5V. A background noise "drone" is generated by the VCF ...
And the envelope is also badly triggered.
Yet it is written in the user manual, that it takes a gate 5V. I have big doubts about that ...

But there is little time with a friend, i tried to play the pro one with his 181 Roland keyboard (100M) and i found that it worked wonderfully well. According to the service manual of the Roland 181, its gate out transmitted 14V. His 14.7V was measured precisely. My friend suggested, i add a gate booster:

I deleted the trig out, but i did not have to. I transform gate 5V or 12V, near 15V.

I made a video but in French because i do not speak English, sorry:
the x0xb0x and 303 have an output protection resistor and diode on the gate out. this sometimes causes poor triggering or no triggering.
^What guest said. I’m sure I recall reading about this exact issue with a Sequential synth on the x0xb0x forums while looking for something else.
Pro-One gate is defintely 5V. I have measured it, and also just hooked up my PRO2021 clone to a real Pro-One via CV and Gate and it worked great. Just like playing the synth itself.

On the Pro-One, the Gate IN simply goes thru a protection Diode (1N914) and then straight to the envelope chip (CEM3310). The spec for the gate signal is +2.4V on to +Vcc (15V), so it is quite forgiving.
Yes i measured the gate out and i saw that it transmitted 5V. But i did not have a 2nd pro one to try. I did it with an additional circuit that lowers the 12V gate from a x0xb0x to 5V.

I was wrong because i was convinced that it needed a higher voltage gate, because it works with the old Roland keyboard 161 and that it does not work at all with a x0xb0x a 303. This has misled me. I did not imagine it was the sequencer that was a problem ...
very frustrating

I did some research on google and found no topic for discussion on this issue. It is often said that Roland, sequential and ARP are Gate compatible, as this is not always the case and it is often more complicated than it seems. hihi
If anyone has a link to the forum discussion topic adafruit? I want to see because I did not see that.

For this to work, with x0xb0x, it might be enough to replace R137 with a lower resistance? I will try with a x0xb0x, i had not thought of this hypothesis! hmmm.....
you could just jumper the diode and resistor for a quick test to see if it works. but, if your other circuit works, just call it done! its a nice build you did to keep it inside the synth.
Yes i just tried, replacing R137 and D34, by jumpers on a x0xb0x. Ilt's perfect! hihi
If not initially, which synthesizer could sequence the TB303, obtaining a satisfactory result, that is to say correctly trigger the enveloppe? Without any modification.
30 years ago, what Roland synthesizer was made to work with? hmmm.....
it was meant to sync with the 606, but it had dinsync for that. the gate and CV outs can work with most roland gear of the time, as they had NPN transistors as the gate inputs stages, with pulldown resistors. the pro-one doesnt have the pulldown resistor, so the diode just charges up the cap, and leaves the gate on.
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