Formant (and jbv!)

[Henri Kovalainen]

Some time ago I mailed about the dual transistors in the formant's exp
converters and it looked like there was no simple (which means cheap and
easy) way to replace them. The VCO is desinged to use the uA726 (dead and
buried) - some nice replacements would be MAT02 (damn expensive) or LM394
(dead), and some of the modules use PNPs that can be substituted with
MAT03 (even more expensive), by matching a pair of single transistors or
by using 2 PNPs of a bigger transistor matrix (CA3096...). The last two
ways will lead to a loose match or to poor heat conductanse.

But now it seems like I have found the ultimate solution:
 the SSM2210 (dual NPN) and the SSM2220 (dual PNP) by Analog Devices.
They are both matched tight and nice, they are still in production (as far
as I know) and they are not so expensive. And the best part is than some
of the specs on these chips are even better than in the MATs! According
to the data sheets, a typical offset voltage drift of the SSM2210 is
0.03uV/C which makes the MAT02 look pretty lame with its 0.1uV/C (if I
remember correctly)!

 ...and it was me who mailed you jbv, and I'm still ready to collaborate
 (though I have already made all the pcbs...).

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