[sdiy] DACs for Arp-style quantizer

[anthony]

Cool. Lots of good things to consider. I guess in my case since I'm using it 
to quantize a filter & flanger (with v/oct response) I probably don't have 
to worry too much about accuracy. Especially since it's a random source 
being quantized. Still I want it to roughly be a diatonic scale. Or actually 
maybe even just or microtonic. I think microtonic would be easy. I had been 
thinking about a way to do scales like that without using a ROM. One could 
see what shape the staircase would need to be and change the circuit somehow 
so that it wouyld do that. I've never bothered to sit down and see what a 
just intotation scale would look like when rendered like a staircase. 
Something like a double-quantizer might do it.

It would be grand if I could whip together a quantizer without having to buy 
anything.

I have looke at the Oberheim quantizer and the Polyfusion quantizer which 
use R2R ladders. They both look very similar. I have actually begun building 
the Polyfusion, but I didn't have enough good resistors. Using a DAC was 
appealing because it's all right there.

I'm going to plug ahead and try something out using:

74HC4040 (since I have a bunch)
CD4044 for the latch maybe (again because I already have some)
LM311 or LM393
TLC7524 or TLC7528 (same as AD7524 etc...)
I could probably justify buying an LF398 or two since they seem to be really 
excellent chips. But I really like Ray Wilson's Single Chip S&H which would 
probably be accurate enough to suit my needs. I like the Arp and Aries S&H's 
too.


----- Original Message ----- 
From: <scottnoanh at peoplepc.com>
To: "harrybissell" <harrybissell at prodigy.net>
Cc: "synth-diy" <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, January 31, 2006 10:40 PM
Subject: Re: [sdiy] DACs for Arp-style quantizer


> Whoa - talk about blonde mode.  I read a post from the archives where you
> were talking about latching, but I understood it to mean latching the 
> output
> of the counter (which would make sense if a ripple counter were being 
> used),
> but you were talking about latching the signal from the comparator to the
> LF398?
>
> Blonde in Kansas
>
>
>
> ----- Original Message -----
> From: "harrybissell" <harrybissell at prodigy.net>
> To: "Grant Richter" <grichter at asapnet.net>
> Cc: "Tim Parkhurst" <tim.parkhurst at gmail.com>; "BrightBoy"
> <jdec at mindspring.com>; "synth-diy" <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, January 31, 2006 6:58 PM
> Subject: Re: [sdiy] DACs for Arp-style quantizer
>
>
>> <blonde mode on>
>>
>> uhhh... hello...?
>>
>> Haven't you heard of the "Wiard MiniWave" ???   :^P
>>
>> H^) harry  (pay no attention to the man behind the curtain :^)
>>
>> Seriously... I was going to build a programmable scale
>> quantizer, but buying the MiniWave was quicker. Finally I DID
>> build a quantizer, freeing up the Minwave to be a wavetable
>> oscillator (as it is better suited).
>>
>> The ARP design is 'ok' if you make some changes... namely
>> you want to add a latch between the comparator output and
>> clock it on the opposite edge of the D/A clock... so that
>> you have 1/2 clock cycle for the comparator to stabilize before
>> clocking the LF398
>>
>> H^) harry again
>>
>>
>>
>> Grant Richter wrote:
>> >
>> > Of course an ADC followed by a DAC only uses 2 chips costing about $4
>> > now a days.
>> >
>> > If you put an EPROM between them, you can have multiple scales.
>
>