Re: tube choice for Leslies

[random@well.com (Ben "Jacobs")]

from Al Goff:
>Ben - You don't need to 'subconsciously' ask --- The tube issue is a sore
>subject with all of us!  Lots of questions, so my post will be long.  Sorry!

Al, thanks for all the info!!!  (I certainly hope nobody on this list needs
to apologize for long postings when there's such useful info to convey!)...
I seem to recall that a previous lengthy exchange on tubes and such was
what finally drove Gilles and the other non-playing,
Hammond-record-collector types to take their discussions over to the new
^Groove^ list, now very active in its own realm.

By luck, more than anything else, I picked Svetlana as a likely source of
quality replacement tubes.  From what I hear, there's plenty of tube stuff
(not just amps!) still in active use within former Soviet economic sphere.
Those crazy deregulated Russians are probably selling 6550-controlled
nuclear power plants to Iran, for all we know.  Yikes.  In any case, one
might hope, they're still tooled up to make tube components at reasonable
quality.  And, next time, I'll be sure to order my Russian tubes from Goff
(what was I thinking?!!!!).

Brad Baker wrote:
>the rectifier replacements ben mentioned, for 5y3, 5u4, etc., are
>solid-state replacements for the tube type rectifiers mentioned. the
>leslie already has a solid-state rectifier so those particular types
>of replacements don't really apply to the leslie amplifier.

Actually, I was looking at the component list for my 22H amp, which still
uses a 5U4GB.  Now I see that my 147 amp DOESN'T have one of these units at
all... I guess the 22H is older, still uses tube rectifier.  Hmmm.

...
A few more questions, if I may indulge myself... In the typical Leslie
application, how long do the typical 6550's need to be in-circuit before
their behavior stabilizes?  (This is the "burn-in" I was talking about).
Do they need to actually be "played", or is it sufficient to heat them up
and leave 'em for a few hours?  Some tube vendors charge a premium for
so-called "24-hr match and burn-in".  A ripoff?  Only for guitarists?

I'm getting the impression that life expectancy for pre-amp tubes is much
longer than for power tubes.  I do want to carry an extra set for emergency
use, though.  The 22H uses a pair of 12AU7's... how important is matching
for these?  Also, ditto the questions above re in-circuit burn-in for
pre-amp tubes....

Thanks again to Al, Brad, and any others who have responded since I last
checked my mail.  Apologies to those who are already happy with their
Quadraverb Leslie simulators and think the rest of us should get our heads
checked!

/************************************************************************
 * ben "jacobs", random@well.sf.ca.us, http://www.well.com/user/random/ *
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