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Prophet 6 "Bug" or "Design Flaw"?
Old 16th December 2015
  #1
Prophet 6 "Bug" or "Design Flaw"?

I purchased a new Prophet 6 on Black Friday which I love but I am getting some very bad distortion issues. I was hoping some others who own it could test this out and see if this problem shows up on theirs:

This distortion happens when the unit is in Sync mode with Oscillator TWO on C1 and Oscillator ONE on Gb2. Some other tuning settings have the same problem but this is one of them. It has to be in Sync mode. Also the distorted sound is ONLY in the Sub Oscillator. The other 2 oscillators are fine. It does not happen all the time. It seems to work fine and then start misbehaving for a couple of minutes and then goes back to normal. I tried retuning which is of little help.

The other problem is that when I wiggle the AC plug where it goes into the unit, the power to it can go off. Then I need to wiggle it again and it goes back on.

If others could test the Oscillator problem it would be appreciated. I am attaching a sound sample ( first time doing this so hope it works ).
Attached Files

Prophet 6 problem more cards.mp3 (1.92 MB, 7783 views)

Old 16th December 2015
  #2
Gear Head
 
patrick_j's Avatar
 
🎧 5 years
I'll test mine when I get home, but from the sound of it, you probably have a faulty board or something. Contact DSI support, they are really great. I initially had a faulty board on my Pro 2, and they were extremely responsive with helping me troubleshoot the problem. Eventually they FedEx-ed my a new main board with detail steps on how to swap it out (which was very easy), and it was good as new.
Old 16th December 2015
  #3
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The behavior you described is the known and expected operation of the sub oscillator when oscillator 1 is hard sync'd to oscillator 2.

The sub oscillator is a triangle wave generated by a flip fop which is driven from the start of oscillator 2's waveshape. When sync is on, oscillator 1's waveshape is retriggered by oscillator 2's frequency. This means that oscillator 2 is retriggered as well, though the frequency of the sub is half that of oscillator 1.

Depending on the oscillators' respective root notes, the sub oscillator may not work consistently from one voice to the next since it is being retriggered at the same time as oscillator 1. As such, I would say that what you are hearing is expected and nothing is physically wrong with the voice boards themselves.
Old 16th December 2015
  #4
I did contact DSI and they sent me a new sound card which I installed and it did not help. The clicks are bad enough that studio clients are not happy. Here is what DSI said to me today:

"The behavior you described is the known and expected operation of the sub oscillator when oscillator 1 is hard sync'd to oscillator 2. The sub oscillator is a square wave generated by a flip fop which is fed from the rising/falling edge of oscillator 2. When sync is on, oscillator 1's waveshape is retriggered by oscillator 2's frequency. Depending on the oscillators' respective root notes and shapes, the sub oscillator may not work consistently from one voice to the next. As such, I would say that what you are hearing is expected and nothing is physically wrong with the voice boards themselves."

My Moog Sub 37 does not have these loud chatter sounding clicks. It's the opposite of smooth creamy analog. - Confused
Old 16th December 2015
  #5
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🎧 5 years
Yup, mine does it too. It sounds god awful.
Old 16th December 2015
  #6
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If you hard sync oscillator 1, the sync response will be creamy and smooth. Due to the sub oscillator's design (derived from oscillator 1) and the nature of hard sync, the sub oscillator's harmonic spectra will peak a bit at specific frequency ranges.

The sub 37 does not behave this way because hard sync runs from osc 1 to 2. The Prophet's is sync from 2 to 1.

So the Sub 37's sub cannot be hard sync'd at all.
Old 16th December 2015
  #7
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🎧 10 years
yeh that's what i was thinking
Old 16th December 2015 | Show parent
  #8
Gear Head
 
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🎧 5 years
Quote:
Originally Posted by AudioSoundzz ➑️

"The behavior you described is the known and expected operation of the sub oscillator when oscillator 1 is hard sync'd to oscillator 2. The sub oscillator is a square wave generated by a flip fop which is fed from the rising/falling edge of oscillator 2. When sync is on, oscillator 1's waveshape is retriggered by oscillator 2's frequency. Depending on the oscillators' respective root notes and shapes, the sub oscillator may not work consistently from one voice to the next. As such, I would say that what you are hearing is expected and nothing is physically wrong with the voice boards themselves."

My Moog Sub 37 does not have these loud chatter sounding clicks. It's the opposite of smooth creamy analog. - Confused
I can understand differences in tonal quality between the voices, but some have a crackle while others don't. I'm not an electrical engineer, so I'm sure this all makes sense in some universe.

Other than that, this is a great synth!
Old 16th December 2015
  #9
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🎧 5 years
Quote:
Originally Posted by AudioSoundzz ➑️
...
The other problem is that when I wiggle the AC plug where it goes into the unit, the power to it can go off. Then I need to wiggle it again and it goes back on...
IMO, the synth needs to be exchanged. That's a potential synth burn out and a fire hazard.
Old 16th December 2015 | Show parent
  #10
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🎧 5 years
Quote:
Originally Posted by DrJustice ➑️
IMO, the synth needs to be exchanged. That's a synth burn out and a fire risk.
Before doing that, check that the cable is firmly seated in the IEC connector. If the plug is not fully seated, then there is possibility that wiggling the cable could cause power to drop out.
Old 16th December 2015 | Show parent
  #11
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🎧 5 years
Quote:
Originally Posted by cbmd ➑️
If you hard sync oscillator 1, the sync response will be creamy and smooth. Due to the sub oscillator's design (derived from oscillator 1) and the nature of hard sync, the sub oscillator's harmonic spectra will peak a bit at specific frequency ranges.

The sub 37 does not behave this way because hard sync runs from osc 1 to 2. The Prophet's is sync from 2 to 1.

So the Sub 37's sub cannot be hard sync'd at all.
I think I'm leaning towards AudioSoundzz assumption that this is a design flaw. In the majority of cases the sub oscillator is used to beef up the sound. I can't see why you would ever want to hard sync it, especially when it generates artifacts like this.
Old 16th December 2015 | Show parent
  #12
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Quote:
Originally Posted by patrick_j ➑️
I think I'm leaning towards AudioSoundzz assumption that this is a design flaw. In the majority of cases the sub oscillator is used to beef up the sound. I can't see why you would ever want to hard sync it, especially when it generates artifacts like this.
It was, in fact, a design decision which we were aware of and decided to move forward with. There are a lot of really cool sounds to be had from the hard sync sub oscillator. For example, check out patch 046.

It's a rhodes like patch where oscillator 1 is synced, the sub oscillator is then turned on/off by oscillator 1's pulse width which is being modulated by osc 2 which is being pulse width modulated by LFO 1. Play some notes and hold the keys, you'll hear the sub oscillator repeat the played notes at a lower frequency.

So, if you ask us here at DSI, it was a considered design choice.

EDIT: also, straight up sync'd sub oscillator sweeps sound really cool as well!

EDIT 2: for edification, we chose not to have the sub oscillator on osc 2 because osc 2 can be used for low frequency poly mod. That would cause one to be unable to use the sub oscillator when using oscillator 2 as a low frequency modulator.
Old 16th December 2015
  #13
The Sub is used 99% of the time to add fullness to sounds - not to be an unpredictable glitchy distorted thing that really sounds terrible. The famous programmers that created patches have piano sounds that randomly add an extra loud octave lower note. Other permanent patches added random clicks. Customers in my studio thought it was digital distortion. I was looking all of over studio for where it was coming from never thinking an analog keyboard would ever do such a thing.

DSI - I am really hoping for a software update so we can choose to turn off this "feature". For me its a no-brainer bad design. All this does for me is remove a Sub Oscillator from many patches that could use it.

Last edited by AudioSoundzz; 16th December 2015 at 02:45 AM.. Reason: typo
Old 16th December 2015 | Show parent
  #14
Gear Head
 
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🎧 5 years
Quote:
Originally Posted by cbmd ➑️
For example, check out patch 046.

It's a rhodes like patch where oscillator 1 is synced, the sub oscillator is then turned on/off by oscillator 1's pulse width which is being modulated by osc 2 which is being pulse width modulated by LFO 1. Play some notes and hold the keys, you'll hear the sub oscillator repeat the played notes at a lower frequency.
I hear ya, and patch 046 is pretty cool, but it still has a lot of nasty pops and clicks that do oddly sound like digital distortion, like AudioSoundzz said.

That being said, this is one small thing (at least in my opinion) in an otherwise pretty awesome synth.
Old 16th December 2015
  #15
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Designer that works side by side with one of the greatest synth design Gurus of all time tells you why it's designed that way ... and he's wrong ... I love learning on GS
Old 16th December 2015 | Show parent
  #16
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🎧 5 years
Quote:
Originally Posted by AudioSoundzz ➑️
The Sub is used 99% of the time to add fullness to sounds - not to be an unpredictable glitchy distorted thing that really sounds terrible.
There are pros and cons to every voice architecture, and as we've discussed, there are cases when the current sub oscillator implementation is preferred or not.

For example, if the sub oscillator were to be derived from oscillator 2 (like the sub 37), then any patches using oscillator 2 in LFO mode could not use the sub oscillator. In this case, it is advantageous to be able to add a sub to a patch which is only using oscillator 1 as a source.

There are bound to be cases the behavior is not preferred, though these cases tend to be a bit less common than the previous one. In your case, you've found that at a specific note ratio, the sub oscillator is on the edge of the harmonic shift space you described. Due to the analog nature of the synth's signal path, slight differences in oscillator pitch are causing the sub to jump across the area in question. If the patch must be set to exactly these note ratios when sync is on, turn off the sub.

Other times, the effect can be very useful in the context of a patch and is musically inspiring. Again, check out patch 046 for one use case. There are likely many other patches in the bank which use the sub in a hard sync fashion which are preferable.

Quote:
Originally Posted by AudioSoundzz ➑️
I am really hoping for a software update so we can choose to turn off this "feature". For me its a no-brainer bad design. All this does for me is remove a Sub Oscillator from many patches that could use it.
I would be happy to add your suggestion to our feature request list, though as far as I am aware, this is likely to not be implemented. Not trying to be a jerk...it's just how it is

EDIT: Yeah after a couple quick minutes of thought, this is definitely not possible due to the voice architecture. There is no way to change this behavior in software.
Old 16th December 2015 | Show parent
  #17
Gear Guru
 
Derp's Avatar
 
🎧 10 years
Quote:
Originally Posted by cbmd ➑️
The behavior you described is the known and expected operation of the sub oscillator when oscillator 1 is hard sync'd to oscillator 2.

The sub oscillator is a triangle wave generated by a flip fop which is driven from the start of oscillator 2's waveshape. When sync is on, oscillator 1's waveshape is retriggered by oscillator 2's frequency. This means that oscillator 2 is retriggered as well, though the frequency of the sub is half that of oscillator 1.

Depending on the oscillators' respective root notes, the sub oscillator may not work consistently from one voice to the next since it is being retriggered at the same time as oscillator 1. As such, I would say that what you are hearing is expected and nothing is physically wrong with the voice boards themselves.


Hey guise, while I'm not one to defend DSI's build quality (sorry, but I still can't forgive them for that first batch of Evolvers and those shoddy encoders), this dude right here is correct. If any of you cats have a modular, try connecting an audio divider to an oscillator that is slaved to another instead of connecting to the master oscillator. Play around with the tuning and you'll get all kinds of fun glitchy noise artifacts. It's not a design flaw, that's just how they work. Suboscillators work by detecting the rising part of an oscillator cycle and flipping either on or off to create a square wave. If that cycle is constantly being reset (i.e. synced,) you've got a moving target for this suboscillator to try to pin down. Sync to the master oscillator and you'll get no problems. Instead of being upset about it, either stop doing it, or exploit it.

Last edited by Derp; 16th December 2015 at 03:13 AM.. Reason: gramrar
Old 16th December 2015 | Show parent
  #18
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Quote:
Originally Posted by cbmd ➑️
... Other times, the effect can be very useful in the context of a patch and is musically inspiring. Again, check out patch 046 for one use case. There are likely many other patches in the bank which use the sub in a hard sync fashion which are preferable.
i'm a big fan of "noise", but can anyone here post an example of "this effect" (that blatant nastiness in the OP's example) being "useful and musically inspiring"? that sounds "broken", and not in a good way.

maybe a minute or so with patch 046?
Old 16th December 2015
  #19
Thanks DSI for getting back so fast regarding this. You did send me new audio card very quickly which I appreciate.

Update - The electrical connection went off again and I pulled the plug in and out and a crunchy sound happened inside the box and now no power is going to the Prophet at all. Even Prophets need power. I am hoping that the hardware is designed to take the stress of simply plugging in the power cable over and over again which many musicians do. I only did it about 10 times for sessions in different parts of the studio.

Sorry to hear that a software update cannot give us more options. I personally think the design decision what not the best. I hope other are not have power plug input thingy breakage. I love the keyboard even with its shortcomings so its going back to Sweetwater for an exchange.
Old 16th December 2015
  #20
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I don't understand the problem. I don't own the P6 yet. The oscillator can't be turned off and it creates this noise on any sync? Or you just wish you could use it during sync for a beefier sound? If this is a natural analog behavior then what's the big deal. Turn off the sub when designing sync patches.

With all respect to OP - I would love to know what clients are so specific as to demand hard sync synth lines that also include sub oscillator.
Old 16th December 2015 | Show parent
  #21
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🎧 5 years
Quote:
Originally Posted by Delmarva ➑️
I don't understand the problem...The oscillator can't be turned off and it creates this noise on any sync? Or you just wish you could use it during sync for a beefier sound?
The latter.
Old 16th December 2015
  #22
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🎧 5 years
Is the clipping something closing the filter a bit can alleviate? The sample clip was wide open, right?
Old 16th December 2015
  #23
As someone previously said "The sub 37 does not behave this way because hard sync runs from osc 1 to 2. The Prophet's is sync from 2 to 1." This was the design choice DSI made and Moog went a different way. I am not expert so I am going with what I am learning here. For me the problem is that many great sounding patches that use hard sync can't benefit with the Sub as they glitch out. Its not always a problem, it depends on where the detuning is set. It just so happens is that places that sound really good often are right where the glitching starts. From what I hear if the Moog Sub 37 model was used, then this would not be a problem but then again the Sync would not effect the Sub is some cool distorted ways which can be useful as well.

Thanks again DSI and everyones help with this. I will revisit the issue when my power issue is fixed which I know will happen as DSI and Sweetwater have great customer service.
Old 16th December 2015 | Show parent
  #24
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Quote:
Originally Posted by AudioSoundzz ➑️
From what I hear if the Moog Sub 37 model was used, then this would not be a problem but then again the Sync would not effect the Sub is some cool distorted ways which can be useful as well.
As cbmd pointed out, the other issue with implementing it the moog sub 37 way is that if you were to use the 2nd osc as an lfo, you could not use sub, which is a worse trade off in my opinion.

Just making sure you got that part.
Old 16th December 2015
  #25
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I just like that cbmd from DSI came on and addressed the issue head on.

Top notch, I'd say, even if you don't agree with their design choice.
Old 16th December 2015
  #26
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I'd like to hear more examples of this in action. The fabled 046 patch, anyone?
Old 16th December 2015
  #27
Update on the power cord issue. As I mentioned I was getting power outages when I moved the cable a little at the back of the synth. I was using a couple of generic power cords on the synth as we have a bunch hanging on our wall cord holders. So this morning I opened the bag that had the cord supplied with the Prophet on a hunch that maybe that one would work better even though I thought that all power cords are the same. And for some weird reason that cord seats into the socket better and does not have any problems. It seems its a bit smaller and goes farther into the socket and makes a firm connection. Whereas the generic cords are bigger and do not fit correctly. This is a first for me, but I am glad that a fix has been figured out.
Old 16th December 2015
  #28
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Makes me nostalgic for the Roland SH32...turn hard sync on and it becomes monophonic and the filter is disabled.

Hey the Prophet 5 didn't even have a sub...epic fail!

Waitaminnit...the sub is generated by a flip flop? That's digital! Quick, light up the torches and start marching to SF to take care of this heresy.
Old 16th December 2015 | Show parent
  #29
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Quote:
Originally Posted by dr_Jezz ➑️
Designer that works side by side with one of the greatest synth design Gurus of all time tells you why it's designed that way ... and he's wrong ... I love learning on GS
It's called feedback and companies learn from it. Real musicians' opinions on instruments should be listened to. Synth designers aren't infallible. They're engineers - and engineers love to improve things and advance the art.

(The above is not a dig at DSI, it's a general comment, and DSI is doing very well in their interaction with customers. FWIW, I'd love to get my hands on a P6!)
Old 16th December 2015
  #30
Here is the famous patch 46 playing chords and a single note repeated. This sound features the Sub oscillator Hard Synced. My opinion is that the detuned kind of thing is cool ( slop is off ) but the clicks are not usable so I would have to edit the performance and remove those. But I am a picky producer working with pretty picky artists.
Attached Files

Patch 46 Chords.mp3 (1.38 MB, 6043 views)

Patch 46 Single Notes.mp3 (747.8 KB, 5914 views)


Last edited by AudioSoundzz; 16th December 2015 at 03:01 PM.. Reason: Added info.
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