There's nothing random about an eight-note poly synth cycling through all the oscillators and repeating usage every eighth key press. See page 35 of the service manual for an explanation of the pitch data path from the CPU, to decoding, etc.
By the way, how far off is the detuning? Is it a half-step, octave, etc.?
Korg DW 8000 - Every eighth note pressed is a lower pitch?
Moderators: Sharp, X-Trade, Pepperpotty, karmathanever
Asking again:
Since the the DW-8000 has a DCO (Digitally Controlled Oscillator), or more precisely the same digital engine generates all waveforms for all oscillators, this can hardly be an 'oscillator out of whack'. What I suspect is that the pitch modulation circuit has some weird interference with other control voltages of osc8.
Try to set up pitch modulation for the program (LFO, for example) see how each of the eight oscillator reacts. Also, try to hold down each previously pressed key and see whether the pitch of all previous notes are affected when you arrive to osc8, or only the 8th? You can also check how the pitch bend lever affects the problem, and what happens if you change the bend range. Lastly, pull the 'tune' control low, fully. Does the detuning still occur?
You wrote it only occurs in poly1 mode. Have you tried poly2 with 8 keys held down at a time (that's the only way to fire osc8 in poly2 mode)? Also isn't there any such detuning in unison modes?synthjoe wrote:Is it the same thing with all programs?
Since the the DW-8000 has a DCO (Digitally Controlled Oscillator), or more precisely the same digital engine generates all waveforms for all oscillators, this can hardly be an 'oscillator out of whack'. What I suspect is that the pitch modulation circuit has some weird interference with other control voltages of osc8.
Try to set up pitch modulation for the program (LFO, for example) see how each of the eight oscillator reacts. Also, try to hold down each previously pressed key and see whether the pitch of all previous notes are affected when you arrive to osc8, or only the 8th? You can also check how the pitch bend lever affects the problem, and what happens if you change the bend range. Lastly, pull the 'tune' control low, fully. Does the detuning still occur?
Synthjoe, you might download the service manual, and read the description which explains how much of the circuit Korg considers the "oscillator". It's on page 35, under "Oscillator operation". A comparison of that description could be made with the schematic, possibly providing further insight.synthjoe wrote:Since the the DW-8000 has a DCO (Digitally Controlled Oscillator), or more precisely the same digital engine generates all waveforms for all oscillators, this can hardly be an 'oscillator out of whack'. What I suspect is that the pitch modulation circuit has some weird interference with other control voltages of osc8.
Yeah, it's from that document - but a different page, the block diagram is of little help in this case.
DCO ends with IC42 (DAC-08), whereby oscillator signals are demultiplexed in the analogue domain by IC17-IC20 (4xCD4066). Any hardware failure before that point would affect all oscillators - but hardware failure after that point (i.e. in filter, EG and delay sections) cannot cause a consistent pitch change of a semitone across the full range.
The DCO can be influenced (pitch-wise) in two ways: 1. via DWGS clock VCO (Q6 & Q7), 2. from software, by altering the PAI value (phase angle increment).
Failure in the first would most likely result in all eight (or rather sixteen) oscillators detuning - hence my suggestion to sound eight notes at a time.
The second, on the other hand, means that either there is a software failure, or that the external analogue control signals (e.g. bend joystick position, LFO D/A conversion, perhaps modulation, portamento pedal or aftertouch) are somehow affected by oscillator demultiplexing (maybe a short on the board, or similar).
To track down the problem in this latter case, the first step would be investigating which pitch control element is not working properly for osc8 (joystick bend/modulation, portamento pedal, LFO, etc.).
DCO ends with IC42 (DAC-08), whereby oscillator signals are demultiplexed in the analogue domain by IC17-IC20 (4xCD4066). Any hardware failure before that point would affect all oscillators - but hardware failure after that point (i.e. in filter, EG and delay sections) cannot cause a consistent pitch change of a semitone across the full range.
The DCO can be influenced (pitch-wise) in two ways: 1. via DWGS clock VCO (Q6 & Q7), 2. from software, by altering the PAI value (phase angle increment).
Failure in the first would most likely result in all eight (or rather sixteen) oscillators detuning - hence my suggestion to sound eight notes at a time.
The second, on the other hand, means that either there is a software failure, or that the external analogue control signals (e.g. bend joystick position, LFO D/A conversion, perhaps modulation, portamento pedal or aftertouch) are somehow affected by oscillator demultiplexing (maybe a short on the board, or similar).
To track down the problem in this latter case, the first step would be investigating which pitch control element is not working properly for osc8 (joystick bend/modulation, portamento pedal, LFO, etc.).
Done this just now, its the 6th.T3owner wrote:Blueowls, since you are going to do further testing...
When you first turn the DW-8000 on, how many key presses does it take before the detuned note is heard? (This is not necessarily the eighth one, even if from that point forward it repeats every eight presses.)
I've gone through things again. In Poly 1 mode the synth will play a detuned sixth note per 8 notes played. In Poly 2 mode it will only detune when eight keys are pressed at once (the sixth being detuned). In Poly 1 and Poly 2 modes I can't seem to get the same error.synthjoe wrote:Asking again:synthjoe wrote:Is it the same thing with all programs?
What about unison mode? I understand that only the 6th note is detuned, not all notes when you get to press and hold the 6th key. Which means that DCO should be fine - it is likely a software/setting problem or something really obscure...
Do controls, like pitch bend, LFO have an effect on the detune? Test mode 7,8 is not described in detail in the service manual and I guess it is not very intuitive to figure out. However, you might want to give it a go, maybe that's where something was tinkered with...
Do controls, like pitch bend, LFO have an effect on the detune? Test mode 7,8 is not described in detail in the service manual and I guess it is not very intuitive to figure out. However, you might want to give it a go, maybe that's where something was tinkered with...
s**t, I just saw I wrote "poly 1/2" instead of unison modes 1&2 in my above reply, sorry!synthjoe wrote:What about unison mode?
Something interesting happened while pitchbending using the joystick and pressing eight keys simultaneously.. Basically when I bent it a half step there was an audible "shift" where it seemed the detuning resolved itself. So I's say YES, controls have an impact.
What are these test-modes you touched on in your reply? And yes, the service manual is not very intuitive to figure out for a novice...
Both unison modes sound all eigth oscillators simultaneously with a single keypress, so no need to press more than one key in either of the unison modes - you should ge the same result with one or eight keys down.
Sorry, I cannot really help with the test mode as I don't have a DW8000 and the manual is useless concerning the details.
But from the pitch bend behaviour you describe I conclude that it will be a problem related to analogue control voltages (the obscure bit I referred to
), in particular those affecting the bend voltage reading. Since the chain of generating this - and other, potentially related - voltage is rather complex, I'm afraid it will not be possible to help further debugging remotely. You'd need an oscilloscope and some experience with electronics troubleshooting to proceed. In lack of such I'd suggest you to take it to a skilled electronics repair person together with the service manual - the good news being that the problem is probably fixable without the need for exotic components.
Good luck!
Sorry, I cannot really help with the test mode as I don't have a DW8000 and the manual is useless concerning the details.
But from the pitch bend behaviour you describe I conclude that it will be a problem related to analogue control voltages (the obscure bit I referred to
), in particular those affecting the bend voltage reading. Since the chain of generating this - and other, potentially related - voltage is rather complex, I'm afraid it will not be possible to help further debugging remotely. You'd need an oscilloscope and some experience with electronics troubleshooting to proceed. In lack of such I'd suggest you to take it to a skilled electronics repair person together with the service manual - the good news being that the problem is probably fixable without the need for exotic components.Good luck!
Hey blueowls, if only some notes are off with oscillator 6/voice1, try to replace IC 55. This will likely fix your problem (suspected a defective bit in one PAR register with this RAM.Blueowls wrote:Half-step.T3owner wrote: By the way, how far off is the detuning? Is it a half-step, octave, etc.?
Greetings.