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SEQUENTIAL/DSI => Prophet => Sequential Prophet-6 => Topic started by: DaveP6guy on June 17, 2018, 12:38:30 PM

Title: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: DaveP6guy on June 17, 2018, 12:38:30 PM
Hi everyone,

I've been using my Prophet-6 now for about 4 months. It's been a lot of fun, the most enjoyable synth I have played. I did have a P5 at one time, so that's saying something! The P5 was a piece of music history but it broke and was 30+ years old. It's so good to have a new machine to replace it. Perhaps in some ways I enjoyed the P5 because of its history but the P6 for me is easier to use and program.

Now I do have a slight issue. I'm not sure if it is an issue with tuning on one of the voices of my P6. I have a couple of questions on voice allocation / assignment and voice defeat.

I know Carson mentioned in the synth4ever interview / tour video that you can defeat voices on the OB-6 (as you could on the old OB-8 I believe) but what about the Prophet-6? I can find nothing online about it.

Q1: Can the user defeat a voice on the P6 and if so, how?

The second question is to do with the tuning of the P6. Mine is relatively early, s/n 0383 (late 2015?/early 2016?) and sounds great but sometimes the tuning on one voice seems a bit sour. It seems to be worse on some patches than others. I'm not sure if it just one voice but if I use the arpeggiator, it seems to come around either on the same note or maybe it moves around a bit as the music progresses. It sometimes seems to correct itself.

I feel at other times there is a slight nuance to the tuning that gives a wondeful real analogue sound or at least a sound that I love so I don't really want to change anything right now.

I'm gonna prepare a video of a recording of this but here is my P6 on a normal day:
https://www.youtube.com/watch?v=cp9ReaQyhas
DSI Sequential Prophet-6 VCO analog synthesizer demo sweet tone. Wonderful filter IMHO.

My second question is:

Q2: Is it easy to tell without an oscilloscope if it is one voice that is sometimes a little iffy on tuning and if so, how?
Q3: Does the internal digital signal processing that monitors the control voltages get fooled with certain types of wave, like maybe very narrow pulses with PWM?
Q4 (What I would really like no know). Does the  internal DSP that monitors the control voltages actually rank the voices from best to worst, and then put the worst voice to the back of the queue, because I have noticed that sometimes the slightly dodgy note does not appear if I am not using all 6 voices? If so, that would be really cool.

Any info esp on Q1 and Q4 would be great!

In the meantime, I have been looking for videos/photos with Rev 1 Prophet-5s on the link below. Sky Toccata and Peter Gabriel and Yes 1978 (photos only) being the main ones I have found so far.

Cheers,
Dave Bellamy (UK).
https://prophet-5.blogspot.com/







Title: Re: Voice assignment defeat on Prophet-6 OB-6?
Post by: IAA Music on June 17, 2018, 02:06:57 PM
Hi Dave, Iím not sure I can answer your technical questions - DSI probably could though. I did wonder whether youíve calibrated the synth much. I had a similar issue and had a dodgy voice card. All sorted now but just wondering as I think all voices should be in tune together as it were!
Title: Re: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: Robot Heart on June 25, 2018, 04:30:07 PM
Voice Defeat:
* Depress a key (that presumably isn't working/making sound), depress Glide and hit Hold. That voice gets ignored until power off.

Q2: Using your ears is the best way, by comparing how a voice sounds to the other 5.
Q3: Not quite sure what you're asking here, I'm going to say no, the DSP doesn't get fooled but feel free to expand on your question.
Q4: No. However, the voices don't always play in ascending order. Playback order is determined by a number of factors such as oldest note in sustain stage, oldest note in release stage, loudest note, quietest note, etc.

Since the P6 & OB-6 have a total of 48 tuning tables, it's best to calibrate the voices anytime you hear it go out of tune. Eventually you will have the instrument calibrated for your environment and it should rarely, if ever go out of tune after that unless operating conditions change.
Title: Re: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: DavidDever on June 27, 2018, 03:14:48 PM
In the meantime, I have been looking for videos/photos with Rev 1 Prophet-5s on the link below. Sky Toccata and Peter Gabriel and Yes 1978 (photos only) being the main ones I have found so far.

Cheers,
Dave Bellamy (UK).
https://prophet-5.blogspot.com/

There should be photos floating around of Roger Powell on one of the late 70s David Bowie tours with one.
Title: Re: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: DaveP6guy on July 04, 2018, 01:54:52 AM
In the meantime, I have been looking for videos/photos with Rev 1 Prophet-5s on the link below. Sky Toccata and Peter Gabriel and Yes 1978 (photos only) being the main ones I have found so far.
https://prophet-5.blogspot.com/
Reply:
There should be photos floating around of Roger Powell on one of the late 70s David Bowie tours with one.

Yes, OT is know!

Actually I found another Peter Gabriel one. A strange TV studio performance of Humdrum, must be around 1978.

Found this on a boring night in hopeless England in 2018, what a find! Drum free Humdrum with Prophet-5 and Polymoog (most likely 1978):
https://www.youtube.com/watch?v=EcpAV4dITwo

Humdrum (flute) RockPalast Live 1978. Loads more Rev1 on there:
https://www.youtube.com/watch?v=amxDkP_0gxs&t=09m41s

Thanks for the David Bowie / Roger Powell idea. I shall have a trawl for that!
Yes, you are right. There it is in the first minute!
https://www.youtube.com/watch?v=Y9pKUSTsxIU

Yes, I'm a naughty boy posting about old Sequential stuff. Won't do it again. Anyway, I am trying to get to grips with my P6 tuning issue and I shall try the voice defeat option mentioned here by RH.
Title: Re: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: DaveP6guy on July 05, 2018, 05:42:12 AM
Voice Defeat:
* Depress a key (that presumably isn't working/making sound), depress Glide and hit Hold. That voice gets ignored until power off.

Q2: Using your ears is the best way, by comparing how a voice sounds to the other 5.
Q3: Not quite sure what you're asking here, I'm going to say no, the DSP doesn't get fooled but feel free to expand on your question.
Q4: No. However, the voices don't always play in ascending order. Playback order is determined by a number of factors such as oldest note in sustain stage, oldest note in release stage, loudest note, quietest note, etc.

Since the P6 & OB-6 have a total of 48 tuning tables, it's best to calibrate the voices anytime you hear it go out of tune. Eventually you will have the instrument calibrated for your environment and it should rarely, if ever go out of tune after that unless operating conditions change.


Thanks for that RobotHeart.

I'm going to say that the time I noticed it first was with patch 370 for some reason and pothers that I created by editing it. It seems to give 3rd that are not right sometimes. Patch 370 has a particularly harmonically rich sustained sound and is buzzy on the ears; maybe that's why it's easy to hear any sour notes.

I've been having a go in panel mode at using some simple waveforms (saw, square), turing up Osc1, then 2 and detuning to hear beats then cycling through the voices if I can.

Someone said the arpeggiator cycles through the voices. Anyway, if I do a one note arpeggio and put it on hold, with a sustained sound and play the arpeggio slowly, 30bpm with long notes, I can hear differences. If I put pan spread on, I can hear the voices move between the speakers. I'm presuming it is cycling through the voices therefore. I can sometimes hear significant differences in the beat frequencies, sometimes perhaps a little too much. It depends on how much detune between Osc1 and Osc2 that I set but there is definitely quite a bit of drift sometimes: I get the odd sour note, let's say - and then when I think, "Ha! I've GOT YOU!" it stops doing it! I have some video clips and some bit recorded on cassette tape. I will post them sometime.

I'm glad the voice defeat function is only until switch off because that would allow me to do it and have it not be permanent. Otherwise I would have to ask you how to un-defeat it as well!
Title: Re: Voice assignment and defeat on Prophet-6 & OB-6?
Post by: station2station on January 17, 2021, 09:09:18 AM
Found this on a boring night in hopeless England in 2018, what a find! Drum free Humdrum with Prophet-5 and Polymoog (most likely 1978):


Humdrum (flute) RockPalast Live 1978. Loads more Rev1 on there:


Thanks for the David Bowie / Roger Powell idea. I shall have a trawl for that!
Yes, you are right. There it is in the first minute!


Yes, I'm a naughty boy posting about old Sequential stuff. Won't do it again. Anyway, I am trying to get to grips with my P6 tuning issue and I shall try the voice defeat option mentioned here by RH.

Oh my, that Humdrum video - that has to be a rev 1 or an early rev 2 prophet being 1978. (I think Dave Smith has said not a lot of rev1's got out the door).  Incredible video.