[sdiy] Re: SDIY Withdrawal Symptoms

[Magnus Danielson]

From: harrybissell <harrybissell at prodigy.net>
Subject: Re: SDIY Withdrawal Symptoms
Date: Thu, 05 May 2005 22:19:18 -0400
Message-ID: <427AD425.580475A3 at prodigy.net>

Hi Harry!

> Modules could be like the old ARP potted modules, minus the potting. SIP
> SMT modules would probably be best as long as height was kept down...

What didn't work *that* well on the ARP modules was the pins IMHO. A better
solution is needed.

> I was not 'joking' about standardization... some people will swear by +/-5V
> control and audio signals, some by +/-10V ... some with some 'oddball' values.

For VCOs, having +/- 5V or 0-10V as standard range is good, but I had my ASM-1
VCO using way more than that before it reached the end-points.

For the SAS-modular project I think we had audio in +/- 5V and CV in 0-10V.
Yes we did:

http://www.jacek.nu/sas/standarder.html

Top-page:
http://www.jacek.nu/sas/

> At least we would not have to deal with the 1/4" vs 1/8" vs Banana issue.

Yes, since everyone is using XLR, right? :P

> Supply voltages are another issue... do you use +/-12 or +/-15 ... or today we
> might even be moving toward +5V or 3.3V  (I don't LIKE it but it is moving that
> way)

+/- 15V _PLEASE_ +5 and +3.3 relates to the digital world (at higher speeds we
are leaving 3.3 behind too).

> Some people will want a 'same-as-except' ... can I get mine with different input
> etc.
> 
> So here's a spec idea ???
> 
> Input impedances 100K or higher
> Output impedances - 1K or lower  (100 ohms ?)
> Supply Voltages - +/-12 ~or~ +/-15

+/- 15 V gets my vote.

> All parameters CV controlled

For _some_ designs this can be more expensive than usefull, but it should be
the goal for most modules.

> Size - 1.5" x 2"  (or 2.5" ?)  or millimeter size ?

Go metric! The electric world is doing it anyway! (making a very serious point)

> Pin Spacing - .1"  (to use standard header pins ?)

2 mm stuff is available (just to make my point, but 2,54 mm stuff will work).

> If these were to be viable, they would have to be mass
> produced.  I doubt we could get concensus on a design.
> 
> Modules I'd like to see
> 
> VCO - Saw & PWM

Here we could use the SAS-VCO, which is basically an ASM-1 VCO with added tri
and sine. Maybe combine it with my saw phase modulator? This was what many
felt we should have done with the SAS-VCO in the first place.

http://www.jacek.nu/sas/vco.html

> VCF - any
> VCA - any

The SAS-VCA still needs debugging and fixing after the _second_ round. Argh!
I can get that kicked up to speed again if needed.

> ADSR -
> Noise -

The ASM-1 noise source maybe?

> Expo converter (tempco or temp compensated)

Go for a good compensation-scheme. There are some nicer onces available now
that is better than the classics.

Cheers,
Magnus