[sdiy] Formant and ASM-1

[Tim Ressel]

-- Gene Stopp <gene at ixiacom.com> wrote:
> OK I must admit the tube ladder VCF has caught my
> attention. If we can put
> together a cascaded transconductance lowpass out of
> vacuum tubes (with
> resonance of course) I'd be all over that. Are you
> listening Eric? :) Is
> this possible, or have you baited us in the hopes
> that we will get off our
> duffs and own up to some thermionic experiments of
> our own? 

No, Gene, I wouldn't do that to my DIY bretheren. The
beastie is actually working (kinda) on my bench.
Admittedly it has a long ways to go before it could be
called finished. But it looks quite hopefull.

> Now I must admit
> that when I woke up this morning I had no idea that
> by the end of the day I
> would be quietly distracted, tallying in my head
> just how many tube sockets
> I'd need to find, and whether or not that un-used
> NOS 375-0-375 VAC
> transformer on the garage shelf would be a good
> starting point? Oh yeah then
> there's those nice coke-bottle 5U4's in the
> drawer... and I do have an old
> Wurlitzer chord organ somebody gave me that's not
> working... it's got a few
> dozen 12a-something-seven's in it... hey! Lookit all
> them sockets! Better
> schedule a trip to All or Apex to get some 1/2 watt
> resistors...

For all you budding tube mongers, Mouser has a itty
bitty transformer that has dual 115VCT 25mA
secondaries. So it could do 100V, 200V, or a doubler
gets you even higher. 25mA is not much, but for small
circuits, its plenty. For example, it can power my mic
preamp which sports a 12AX7, 12AU7, and 12BH7. Of
course there are plenty of transformers for heaters,
including switchers.

> 
> My wife will soon figure out that something's up...
> I'd better be careful.

Yeah, wives can always tell by that glassy look in
your eyes  ;-)

--tr


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