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Re: [sdiy] Quantix-8 Wavetable / Quantizer important update
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fonik



Joined: Jun 07, 2006
Posts: 3950
Location: Germany
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PostPosted: Thu Mar 04, 2010 12:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Sebo wrote:
Hi Fonik:
I have the MIDI to CV upside down, the quantizer works OK as I added an
inverter switch to the input Smile
I think that if the quantizer works, the wavetable should work too, as both
use the ADC the PIC, the RAM and the DAC, if some of this were
damaged, or any of the circuits related (buffers, etc) neither modes would
work. Well... there is a small chance that the PIC gets some damage and
part of the code is corrupted, but that would be very strange.
Wave pot and Wave CV pot are sumed then go to the PIC, same with the
Bank pots, so if they work now I don't think that the miswiring affected
any other part of the circuit.
Hope you solve this soon.

today i am not sure if i tested the quantizing the correct way. will have to get back on this. i have the gut feeling that the ADC isn't working correctly, however i will have to do more tests...

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matthias
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Sebo



Joined: Apr 27, 2007
Posts: 564
Location: Argentina

PostPosted: Fri Mar 05, 2010 9:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi:
If the ADC isn't working check the frequency of the clock, when I built mine,
the clock was too high, even with the trimm at minimun, so I had to mod
the circuit (I described that in an early post). Finally my clock is 417KHz
aprox.
If the clock is too high the ADC will not work, and when the clock is a little high
you get erratic behavior.

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fonik



Joined: Jun 07, 2006
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PostPosted: Mon Mar 15, 2010 4:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

yep, sebo: the ADC isn't working.

i see the incoming 0-5 at the input, the clock at pin 6 & 9, mode is HI (pin 7), -ref and +ref are fine, however all bits are LO exept DB7 (pin 17).

i replaced the ADC since i feared it could have been fried due to the wrong wiring and magic smoke when first powering the module, alas it has not been a faulty IC...

concerning the clock: i jsut don't know how to calculate the frequency with a scope. for the slowest clock i get with adjusting R6 i measure 12 minor digits for a full cycle, with the scope set to .5 us.
do the cycle duration will be 24 x 0.5us = 12us (or micro seconds)? how to calculate the frequency then? F=1/T?
then the frequency would be F=1/12us=83.33kHz??? i think that's wrong. could anybody help me, please?

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cheers,
matthias
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blue hell
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Joined: Apr 03, 2004
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PostPosted: Mon Mar 15, 2010 4:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Time scale for a scope is always per major division, and you'll have 10 major divisions on your screen usually. Then a major is divided up into 5 minor divisions usually ... so it sounds like your frequency is actually 5 times as high? (f = 1/T is correct).
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also .. could someone please turn down the thermostat a bit.
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Sebo



Joined: Apr 27, 2007
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PostPosted: Mon Mar 15, 2010 5:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yep, 5 x 83.33KHz = 416.5KHz, that seems right.
With that clock the ADC should be working, but try to lower it a bit more,
supposedly the ADC should work with higher clocks, but mine didn't, so I
think that varies a lot from chip to chip.
Also check the input isn't overloading the ADC, that's cause the ADC to
lock up in some way (funny when using it as distortion because if you push
hard you get some kind of stuttering, but too hard and the thing mutes itself).

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fonik



Joined: Jun 07, 2006
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PostPosted: Tue Mar 16, 2010 12:11 am    Post subject: Reply with quote  Mark this post and the followings unread

major divisions Laughing - what did i think?
thank you guy's for taking care. now i've learned how to use my scope for frequency measurements.

okay sebo, so i will try your modification to get lower clock speed. hopefully the ADC will start to work then.

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ATOM



Joined: Sep 20, 2004
Posts: 48
Location: Norway

PostPosted: Tue Nov 23, 2010 3:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi
I have startet to gather parts for this pcb, but have a few problems.

First is the 100n ceramic COG/NPO it´s really hard to find at a fair price, is it really critical to use the COG/NPO type capacitor?
If so do somebody have a cheap source part number?

Also the 5p ceramic, my local parts dealer have 4,7p and 5,6p but no 5p?

Help appreciated.

ATOM
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davebr



Joined: Jun 09, 2007
Posts: 198
Location: portland, or

PostPosted: Mon Jan 03, 2011 9:16 pm    Post subject: Quantix-8 quantizer / wavetable oscillator
Subject description: Documentation
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I just finished repairing a Quantix-8 for a fellow DIY-er (e.g. I don't own one). The ADC would not operate at 500 KHz as was mentioned in previous posts. I took a few scope images and documented some of my learnings. In particular I found a few documentation discrepancies that I fed back to Marc. I put my information on my web site at http://modularsynthesis.com/papareil/quantix8/quantix8.htm

This is a pretty interesting module. I played around with the Gate In mode. The PC software for creating new waveforms makes this a very nice setup.

Dave
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