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Simple Quantizer Boards + Chips rev4 avaialable now.
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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Wed Mar 02, 2011 5:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

The VC clock/divider is a master clock and divider in one chip. There's an undivided master output and four divided outputs, each one has a voltage controllable division and PWM. There's also a VC master offset for division. It'll probably be a couple months before I have boards for sale.

Envelope sequencer is a sequencer that's set up for generating envelope signals. The name probably implies it being a cooler/newer thing than it is. The main difference between it and a Baby 10 style is that it has adjustable loop points for your sustain. I'm partially building it just because I've wanted to use those Alpha lighted slider pots for something and I thought this would be perfect.

Eric, I think a multi-channel version is a great idea and it's do-able. Maybe a 4 channel, 0-10V version of the quantizer might be a good compromise for people that aren't going to want the bloated ton of panel space Deluxe version, but aren't satisfied with the simple quantizer.
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oldmanfury



Joined: Oct 20, 2006
Posts: 53
Location: CA

PostPosted: Sat Mar 12, 2011 5:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello,

Just built a pair of these, and had a question. I'm using Frac-rack +-15V supplies, and thus don't have a separate DGND/AGND. I shorted the two together, which works, however if you look at the CV output on a scope, there is a good deal of high-frequency oscillation on the output. 200 mV P-P, 200us period. Any suggestions on how to deal with this? Put a good sized cap on each output and LPF them?

-Gerald
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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Sat Mar 12, 2011 7:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

With that period on the oscillation it seems like the PWM output is running a little slow, which would most likely be caused by a bad crystal oscillator or maybe a bad 12f683.

I'd suggest replacing your crystal oscillator first so the response of the circuit doesn't slow down any. If that doesn't work, or if you're not worried about response time R2 and C7 are already forming an LPF. I would replace one of these with a higher value.
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oldmanfury



Joined: Oct 20, 2006
Posts: 53
Location: CA

PostPosted: Sat Mar 12, 2011 9:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Both boards are oscillating (nice triangle waves!), so it probably isn't a bad xtal, but I'll check to make sure I bought the right ones.

I'll stare at the schematic, and check to make sure I didn't swap anything and let you know.
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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Wed May 04, 2011 3:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've got a bunch of boards in stock for this design now if anyone's interested.
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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Wed May 04, 2011 4:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

..."I've got a bunch of boards in stock for this design"...wait, which design? Is this the updated layout as in:
Quote:
The new layout has mounting holes for people not wanting to use pc mounted pots and instead of standard chips and octave chips there will be one version of the chip and an onboard jumper to determine which set of lookup tables the chip uses.

Question

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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Thu May 05, 2011 4:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes, this is the updated layout with mounting holes and hardware selectable banks of modes.
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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Mon May 09, 2011 12:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cool. PM sent.

More quantizing is a wonderful thing!

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Rvlt



Joined: Mar 05, 2008
Posts: 21
Location: Berlin

PostPosted: Sun May 15, 2011 5:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello all,

I have a question regarding the precision of quantization.

When I feed the quantizer input with 0-1V, I get the following readings (mode: chromatic steps):


Ideal / Measured

83.3 / 100*
166 / 187*
250 / 269*
333 / 333
416 / 416
500 / 499
583 / 601*
666 / 664
750 / 747
833 / 849*
916 / 933*
1000 / 996


While a few steps are spot on, the ones with the * are not. So if I watch the output of my oscillator on a tuner, these notes are 20-25 cent out of tune (while the others are correct).

Anyone else has this problem? Is the precision of the PIC simply not good enough?

I have the pcb with the 12F683, but I breadboarded the PIC16F864 version a while ago and remember I had the same issues.

Best regards,
lars
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wmonk



Joined: Sep 15, 2008
Posts: 485
Location: Enschede, the Netherlands
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PostPosted: Sun May 15, 2011 8:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Rvlt wrote:

While a few steps are spot on, the ones with the * are not. So if I watch the output of my oscillator on a tuner, these notes are 20-25 cent out of tune (while the others are correct).

Anyone else has this problem? Is the precision of the PIC simply not good enough?

I noted that too, was thinking it was my fault some way, but now I'm thinking otherwise. I see about the same values.

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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Sun May 15, 2011 10:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Lars, you're correct in thinking this is just a limit of the method of digital to analog conversion used in this design.

My goal with this project was to make a quantizer which was musically useful, an easy build and economical; and I feel like it's a success by those criteria. I acknowledge that it is not as accurate as it could be if I had used other methods in the design, and also that something being "musically useful" is subjective. If this quantizer isn't accurate enough to be useful to you, or if you feel like I've misled you in my descriptions I apologize.

I'm going to go back and edit my first post to try and make this more clear for future visitors to the board.
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Rvlt



Joined: Mar 05, 2008
Posts: 21
Location: Berlin

PostPosted: Sun May 15, 2011 5:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Michael,

no need to apologize, not a problem.
I was just curious and wanted to make shure it's not my fault.

btw, if your deluxe version will have a more accurate conversion I would definitely buy it Cool

Cheers,
Lars
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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Sun May 15, 2011 8:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

Glad to hear that, it's hard to interpret people's tone through the internet, so I always play it safe and try to disarm potential arguments.

The plan with the deluxe is to use an external 12-bit DAC chip, so it should be more accurate.
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Rvlt



Joined: Mar 05, 2008
Posts: 21
Location: Berlin

PostPosted: Mon May 16, 2011 4:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Boogdish wrote:
The plan with the deluxe is to use an external 12-bit DAC chip, so it should be more accurate.

thumleft
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fonik



Joined: Jun 07, 2006
Posts: 3721
Location: Germany
Audio files: 23

PostPosted: Thu Jun 02, 2011 3:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

he link in the 1st post to the building docs is broken!? could someone provide me with the documentation?
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Rvlt



Joined: Mar 05, 2008
Posts: 21
Location: Berlin

PostPosted: Thu Jun 02, 2011 4:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

here you go:

http://www.bartonmusicalcircuits.com/cvquant/cv%20quantizer%20documentation%202.0.pdf

it's actually *.pdf , not *.pdff
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fonik



Joined: Jun 07, 2006
Posts: 3721
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PostPosted: Fri Jun 03, 2011 12:43 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks. there is just one f to much in the link in the 1st post.

anyways, i think i must have missed something:
i thought this thread is about building the simple quantizer as shown in the other thread, however, a different pic is used and the latest code (incl mode switch) is not available without the PCB, correct?
this would be okay, alas, i wanted to make make own boards for this. i will have to go with the old 16f... based version, i believe.

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Boogdish



Joined: Sep 21, 2009
Posts: 122
Location: Bloomington, IN

PostPosted: Sat Jun 04, 2011 12:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

I fixed the link on the first post, sorry about that.

Fonik, I'm writing you an e-mail right now.
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LektroiD



Joined: Aug 23, 2008
Posts: 975
Location: Scottish Borders
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PostPosted: Fri Sep 23, 2011 8:54 am    Post subject: Reply with quote  Mark this post and the followings unread

I posted in the other thread, although after searching the forum, my question might be better in this one..

Could someone explain the whole AGND / GND thing to me? I'm not getting the explanation in the documentation at all... I assume it is like this...

with 15V source, use (+15V & AGND)
with 5V source, use (+5V & GND)

is that right?

I'm now wondering which GND/AGND I use to ground the sockets, or is this intended for banana jacks?

If someone could make a simple wiring diagram that would be great, as I'm not translating this from text at all.

Thanks in advance Smile


**EDIT**

I read through and noticed another builder connected both grounds together.

Anyway, I have done this and run it using an LFO, but what happens is the initial note stays stuck for half the time. Is this due to the fact this circuit is not bipolar? If so, how could I offset it so it is?
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LFLab



Joined: Dec 17, 2009
Posts: 179
Location: Rosmalen, Netherlands

PostPosted: Fri Sep 23, 2011 12:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

It does the same with me, it's indeed like you mentioned. The LFO swings from + to - and back, but pitch control voltage is from 0 to + only.
You'll need something that can offset the voltage swing (the one springing to mind is the joystick schematic from CGS, although there are probably a ton of others).
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LektroiD



Joined: Aug 23, 2008
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PostPosted: Fri Sep 23, 2011 12:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

JarnoBassplayer wrote:
It does the same with me, it's indeed like you mentioned. The LFO swings from + to - and back, but pitch control voltage is from 0 to + only.
You'll need something that can offset the voltage swing (the one springing to mind is the joystick schematic from CGS, although there are probably a ton of others).


I guess Fonik's attenuverting mixer would do the trick here. Shame it's not got a bipolar switch.. That would be a handy feature, since the rest of the modules in my system (and many others) are bipolar.
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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Sun Sep 25, 2011 8:00 am    Post subject: Reply with quote  Mark this post and the followings unread

From page 5:
clee wrote:
FYI here is how I'm handling the input overvoltage problem in a PIC quantizer I'm building.

The Op amp U3 will go up to 5 volts and at that point it will be clamped to the output of U9 which is being fed by a 5 volt voltage regulator. You could use the 5 volt supply, but you might get some digital noise flowing into the PIC input.

With Scottky diodes the voltage going into the pic should not go over 5.3 volts and the input should be very linear up to 5 volts.

Craig

Thanks for that!

I started putting one of the new versions on a 19" 2U panel last night and built the circuit referenced above (minus the +5V regulator, as I'll be pulling that voltage from elsewhere). I haven't tested it, but it's a very simple and easy add-on.

In this panel I'm normalizing the input of the quantizer to the S&H output of a YuSynth Noise/S&H, so I though it would be prudent to clamp that down right from the start.

Of course I ordered the panel and put all the hardware on it, built the PCB mounting brackets, then started work on the quantizer PCB itself (which hadn't been fully built)...only to realize I had not put a panel switch for the Octave bank...
scratch

Fortunately, I realized the Rate pot on a next door LFO could be fit with a push/pull switching pot. There are no panel graphics for the Octave bank, but I can at least switch to it...kind of an Easter egg. Nice!
happy smoker

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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
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PostPosted: Sun Sep 25, 2011 8:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Question about the Octave Bank, though....

Any estimate on the voltage needed to switch between the different options?

I'm not using a pot, but rather an 8 pole rotary switch. I'm guessing I'll have to click through several steps of the switch in order to activate changes in the Octave Bank. Just wasn't sure if I'm likely to run into problems using the same resistance divisions I am for the Scale Bank.

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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Mon Sep 26, 2011 8:35 am    Post subject: Reply with quote  Mark this post and the followings unread

To clarify that last question a bit, here's what I'm going to test soon, using a SP8T rotary switch in place of the Scale pot:

Wiring scheme:
Switch Pole => Scale pot's wiper pad
Pin 1 => Scale pot's CCW pad (0V)
Pin 1-2 => 15K ohm (soldered directly between pins 1 and 2)
Pin 2-3 => 15K ohm
Pin 3-4 => 15K ohm
Pin 4-5 => 15K ohm
Pin 5-6 => 15K ohm
Pin 6-7 => 15K ohm
Pin 7-8 => 10K ohm
Pin 8 => Scale Pot's CW Pad (5V)

Switch Position / Volts Out (est.)
1 / 0V
2 / 0.75V
3 / 1.5V
4 / 2.25V
5 / 3V
6 / 3.75V
7 / 4.5V
8 / 5V

Those estimated volt outputs should put the switch positions near the middle of the required range for the normal Scale option. However, I'm not sure what voltages each of the Octave modes require.

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roglok



Joined: Aug 28, 2010
Posts: 156
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PostPosted: Tue May 29, 2012 2:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

hey emdot,

did you ever get around to the switch mod? does it work with your values?
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