Improving accent?
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Improving accent?

by x0xjesus on Tue Nov 20, 2012 4:58 pm

I have Mode Machines x0xbox. Is there anything I could do to make the accent sound more like this?:

http://www.youtube.com/watch?feature=pl ... v0FY#t=73s

On my x0xbox, tuning accent from low to high sounds like this (file x0xaccent.mp3). In the beginning all knobs are low, but then I put them in the max (except decay, which I adjust to max at the very end):

https://www.dropbox.com/sh/r12psr9huwu5jwo/PiVRMA-RSM

BTW, I have replaced the 24 transistors with 2SC536F.
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Re: Improving accent?

by antto on Tue Nov 20, 2012 6:12 pm

uh, it's hard to tell from your audio sample, can you record a sample with ENVMOD at zero and CUTOFF, RESO, DECAY, ACCENT all the way up

apart from that, in the video, the only difference i see compared to a normal x0x is, probably slightly more resonance (reso boost mod) and *maybe* increased accent (R46 mod iirc)
AND a distortion effect of some sort
We are here too: irc.freenode.net >>> #x0xb0x
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Re: Improving accent?

by x0xjesus on Wed Nov 21, 2012 4:22 pm

antto wrote:uh, it's hard to tell from your audio sample, can you record a sample with ENVMOD at zero and CUTOFF, RESO, DECAY, ACCENT all the way up


sample with ENVMOD at zero:
https://www.dropbox.com/sh/r12psr9huwu5 ... t_zero.mp3
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Re: Improving accent?

by antto on Wed Nov 21, 2012 4:30 pm

uh, your accent "wow" is completely missing .. you only got accent making the vca louder

something is wrong somewhere between IC12A thru D24 - R46 - C13
i assume your ACCENT and RESONANCE pots are fine
We are here too: irc.freenode.net >>> #x0xb0x
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VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
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Re: Improving accent?

by x0xjesus on Mon Nov 26, 2012 4:55 pm

antto wrote:uh, your accent "wow" is completely missing .. you only got accent making the vca louder

something is wrong somewhere between IC12A thru D24 - R46 - C13
i assume your ACCENT and RESONANCE pots are fine


I tried resoldering, looking for obious defects etc. And I measured D24 and R46, but I didn't find any problems. However, I noticed that if I bypass R46 with a wire, it doesn't affect accent in any way.

Any hints how to continue "debugging" this - and what would be good way of testing IC12 and C13? I have oscilloscope, if that helps. And I think I can check C13 by removing it first from the board.
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Re: Improving accent?

by antto on Mon Nov 26, 2012 6:04 pm

well, before D24 you should see something that looks like this:
Image
only when there are accented notes AND accent knob is high
this is basically the filter cutoff envelope only at accented notes (so it's with the short decay time)

then, after D24 it is basically waveshaped slightly

R46 reduces it's amount a little

and C13 smooths it (it acts as a LPF)
so at C13 it should look like this:
Image
We are here too: irc.freenode.net >>> #x0xb0x
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VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
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Re: Improving accent?

by x0xjesus on Wed Nov 28, 2012 6:27 pm

antto wrote:then, after D24 it is basically waveshaped slightly
R46 reduces it's amount a little


IMHO, I saw wavefroms which resembled that at D24 and R46. Vpp at D24 was 1,04 volts and 0,720 volts at R24 according to my notes.

so at C13 it should look like this:


I am not sure if I see waveform which is exactly like that at C13. The signal is quite weak at it (the picture says that Vpp is 0,036, but I in my notes I have written 0,08 volts):

Image

However, I am not yet that familiar with oscilloscopes, so I may be doing something wrong. I used heatsink of 7805 on IO board as a ground reference in all my measurements. I am not sure if that was OK.

I removed C13 and checked using multimeter that the capacitance of it was about 1 uF.
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Re: Improving accent?

by antto on Wed Nov 28, 2012 6:41 pm

yes, this is how the signal should look like
i have no idea about the exact peak voltage because i cannot measure it myself
but 36mV peak to peak sounds very wrong

make sure the resistor is the right value, and the diode the right orientation, i don't know
also, make sure your resonance and accent pots are the right values too
check R72 too
We are here too: irc.freenode.net >>> #x0xb0x
..:: c0nb0x v1.00 ::.. http://forums.adafruit.com/viewtopic.php?f=7&t=29282 (new control app - win/osx)
VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
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Re: Improving accent?

by x0xjesus on Fri Dec 07, 2012 11:40 pm

antto wrote:yes, this is how the signal should look like
i have no idea about the exact peak voltage because i cannot measure it myself
but 36mV peak to peak sounds very wrong

make sure the resistor is the right value, and the diode the right orientation, i don't know
also, make sure your resonance and accent pots are the right values too
check R72 too


I noticed that I had configured the oscilloscope incorrectly (the probes were on X10 mode, but on oscilloscope the default setting was for X1 probe) and the real voltages are 10 times the voltages I reported before. Do those voltages sound about right?

I didn't manage to find anything wrong between "IC12A thru D24 - R46 - C13". I also checked that IC12 is working as a switch to that signal. And I think that the signal seems similar to your description at all points between those components.

However, I noticed that for some reason the resonance pot (VR4) seems to be about 800 Kohm potentiometer instead of 50 Kohm. Could that cause the lack of "wow"? And if not, are there any other things I should check? Could some other part of the circuit be "dead" although there should be some kind of signal, which might explain why only volume increases, but there is no "wow"?
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Re: Improving accent?

by antto on Sat Dec 08, 2012 2:49 am

800K ? :shock:
the resonance pot is supposed to be dual 50K linear
if the resistance on it is more, then sure you will get less "wow"

other than that, i really can't tell about the voltages, i don't have suitable measurement equipment, only a cheap multimeter :?
We are here too: irc.freenode.net >>> #x0xb0x
..:: c0nb0x v1.00 ::.. http://forums.adafruit.com/viewtopic.php?f=7&t=29282 (new control app - win/osx)
VCO Tuning: http://forums.adafruit.com/viewtopic.php?f=12&t=24759 (do it the EASY way)
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Re: Improving accent?

by x0xjesus on Wed Dec 12, 2012 9:07 pm

antto wrote:800K ? :shock:
the resonance pot is supposed to be dual 50K linear
if the resistance on it is more, then sure you will get less "wow"


I replaced it with 50K linear potentiometer. Now there is "wow" sound. :)
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