AW: To earth, or not to earth...

[Fraser, Colin J]

> -----Original Message-----
> From:	Martin Czech [SMTP:martin.czech at itt-sc.de]
> Sent:	Thursday, December 04, 1997 9:50 AM
> To:	Colin.J.Fraser at scottishpower.plc.uk
> Cc:	synth-diy at mailhost.bpa.nl
> Subject:	RE: AW: To earth, or not to earth...
> 
> > In practice, wouldn't virtually all sounds coming out of a modular
> be
> > running thru' a vca, and typically arriving at the vca at a high
> enough
> > level to avoid noise pickup?
> 
> If you do the standard vco->vcf->vca patch this is almost the case.
> BUt if you close the filter, vcf output goes down to pretty zero.
> Then side effects may become audible.
> But standard, that's not why i'm building a modular. Other patches 
> may have much lower intermediate levels.
> 
True, but even much lower intermediate levels are still pretty hot with
a 10v p-p range.
BTW I build vcas into the same modules as my filters to minimise the
length of patch cords between them (2-3 inches). If you close a lpf
right down, the only noise at the output should be from the final
buffering stage so maybe a balanced output/input from filter to vca
would be a good idea ?
I certainly can't see the point putting a balanced output on a vco with
a 10 volt swing.

> > Anyone have a schematic for a vca with 120db snr ?
> 
> I keep saying : use SSM2018(T). Cheap, silent, clean, available.
> You can add a log circuit for linear response.
> 
I'll have a look for these - don't suppose they have a balanced output ?

> > BTW I use banana plugs, and a star earth layout - my modular is the
> > quitest analogue I've heard.
> 
> How large is your system? How long are the patchchords?
> Would you say, that your output signal has always CD-Quality.
> I mean, would you record it and master it directly on CD, without
> noisegates etc. That's what I'm talking about.
> 
My systems isn't huge, 4 vcos, 2egs, 2vcegs, 4-2-1 mixer, dual svf/vca,
(dual 2044 lpf and quad lfo on the workbench).
Everything else I use produces more noise - especially my 808/909 drum
circuits, so before I would master anything to CD, I would run it thru a
digital noise reduction process on my PC anyway :-).

On a side point here, I'm thinking of buying an Event Gina audio card
for hd multitracking. These have 20-bit audio resolution, and the test
in this months SOS showed they have over 90 db snr, so maybe I'll have
to invest in some noise gates for my other gear...

Colin f