>From: "Tim Stinchcombe" < timothy@... >
>Reply-To: Doepfer_a100@yahoogroups.com
>To: Doepfer_a100@yahoogroups.com
>Subject: 1 Re: technichals...
>Date: Thu, 30 Mar 2006 20:44:52 -0000
>
>Hi Martin,
>
>The SSM2164 is made by Analogue Devices:
>
> http://www.analog.com/UploadedFiles/Data_Sheets/15183786ssm2164.pdf
>
>which with the right know-how can be turned into a 4-pole 24dB
>filter, or from what Allen Heath have at their website for thr VF-1,
>2 x 2-pole state-variable filters (so basically 12dB each), which
>thus give low-, high- and band-pass, and which if run one after the
>other gives 24dB (hence the 'mono' switch on the back).
>
>I suspect a lot of the quality of the sound comes from the
>overdrive/clipping introduced by the valve input section, but that's
>only a guess - the total sound will depend on both chip and valves,
>but how much it would change, say, if the valves were replaced by
>transistors would probably be difficult to guess without trying it!
>
>Tim
>
> > I´ve asked Allen & Heath tech support what chips they used for the
>VF-!
> > analogue valve stereo-filter. I didn´t get much wiser from the
>answer
> > though.
> > Maybe some one here knows about the chip SSM2164
> >
> > (As you will see this is cuts from 2 different e-mails)
> >
> > >>>The active circuitry in the VF-1 is based on the SSM2163 Quad
>VCA IC in
> > an analogue filter configuration, supported by standard TL072 op-
>amps
> > and of course a pair of ECC82 valves.
> > >Thanks for your reply. Please note the typo in my last reply and
>the fact
> > >that it is the SSM2164, not 2163 IC that is the active VCA.>>>
> >
> > I´m curious, cuz I really love the sound of this machine, and I
>wonder how
> > much of this amusement is due the valve/overdrive section...
> >
> >
> > >
> >
>
>
>
>
>