Formant problems.

[Henri Kovalainen]

I have to admit that the module designs on the Formant are absolutely great,
but however I have had some serious problems particularly with the transistors
used in the exponential converters. If you can answer any of these questions I
would really appreciate if you could do so.

First of all, the uA726 in the VCO. (Now, I knew all the way from the start 
that there was no way in hell I could find this one.) Rick Jansen suggests
the MAT02 as a substitute (with an external heater), but none of the 
companys I phoned had any MATs. So, can I substitute the uA726 with two 
closely matched 2N3904s (these can be used to substitute a MAT02, can't 
they), and build the external heater (and actually use this contraption
with satisfying results)? (By the way, if you have any heater schematics I
would be more than happy to see them)

The second problem lays in the VCA. This uses the CA3084, which I have been
(guess what) unable to find. Rick suggests the MAT03, but as I said, no 
MATs available here.  Well, isn't MAT03 a PNP version of MAT02 and 2N3906 
a PNP version of 2N3904? So,  could I use two 2N3906s to substitute the
CA3084? (Oh, and would this same system work in the converter of the 24dB
filter?)

The last question is about the CA3080. They are very rare (and expensive)
here, therefore I would like to know is there any way to replace this one?
(I would prefer a single OTA, cos it's nasty to use dual OTAs to replace 
single OTAs.)

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| Henri Kovalainen       Hoikankatu 19 '
' Phone: +08 - 626555    87100 Kajaani
  IRC: AcidRain          FINLAND       .
. http://lyseolukio2.kajaani.fi/~dh/   |
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