Odp: [sdiy] Intro, and saving the 901?

[Roman]

Hi,
I don't have the mini or moog modular, but if I was to replicate it,
I'd make it exactly how it was done. Maybe use different components
and make it SMD, but that's all. IMHO there are plenty modulars
available that are simply better <duck>
However I like the look of it, and simplicity of the design, that can be
lost if more and more 'fixes' and 'upgrades' are implemented.
Build it like the original. If you don't like floating tuning, buy a MOTM.

Good luck with it. 

Roman

----- Original Message ----- 
From: Richard Wentk <richard at skydancer.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Friday, October 25, 2002 8:28 PM
Subject: [sdiy] Intro, and saving the 901?


> Hi synth DIY people
> 
> I'm currently playing with the idea of building a Moog Modular clone - love 
> the sound of that thing, even though it's obviously a temperamental design 
> by modern standards. And it could be quite a cheap project.
> 
> I've been looking at the 901 oscillator, and wondering if there's anything 
> worth saving in the design. Obviously it's a given that the exp gen in the 
> 901 has to be replaced with something more modern. But it also seems like 
> the UJT oscillator is going to be inherently temperature sensitive no 
> matter what you do to it. (The specs say Rbb varies by around 0.5%/K) And 
> switching between capacitors for the octave setting doesn't look like a 
> recipe for tuning accuracy. The triangle generation scheme is kind of 
> eccentric too...
> 
> Meanwhile the 921 looks too complex to homebrew.
> 
> So I'm wondering three things:
> 
> 1. Has anyone tried to revise the 901 design and somehow get it more stable?
> 
> 2. Is the sound so much better that it's worth making the effort? I've 
> listened to MP3s of more modern designs but they seem a little cold to me. 
> (I have a suspicion this may be something to do with the op-amps. I built a 
> 3340 design a while back, and the difference between the sound unbuffered 
> and buffered with a TL07x was surprisingly noticeable.) But obviously I 
> haven't heard every single circuit out there. Has anyone tried an A/B 
> between their favourite recent design - one that stays in tune and tracks - 
> and an old 901 or 921?
> 
> 3. Is the Minimoog osc design worth trying instead? How is that for temp 
> stability?
> 
> Thanks for any answers!
> 
> Richard
> 
>