From John.Fisher@utah.edu Wed Jun 13 09:44:15 2007
Subject:RE: Leslie 3300 on it's way!

About the only two things that change on a tube when operated at the low
end of it's design voltage are the overall impedance and signal to noise
ratio. Surrounding components must take this into consideration. Most of
the sound some people like is the distortion caused by the
transformer/tube interaction. There is also some phase shifting at
higher frequencies do to the frequency limits of the transformer.



All of this is non subjective and easily measurable and audible. If you
have a mixer with a channel invert switch, split your signal source
directly to one channel of the mixer and into the pre amp. Feed the pre
amp output into a second channel and reverse the phase (some pre amps
already reverse phase). Sum the channel strips and null the sound with
volume and EQ. What is left is the distortion of the tube circuit. You
may or may not like what you hear but at least it will be clear what is
going on.



John Fisher



________________________________

From: CloneWheel@yahoogroups.com [mailto:CloneWheel@yahoogroups.com] On
Behalf Of jake92028
Sent: Wednesday, June 13, 2007 10:15 AM
To: CloneWheel@yahoogroups.com
Subject: Re: [CWSG] Leslie 3300 on it's way!



--- In CloneWheel@yahoogroups.com
, "jjmcs49" wrote:
>
> I believe you misunderstand how a tube works. You are not
> sending "more voltage" into the amp. Also, I'm no electronics
expert,
> but I think that 24v is within the 12AX7's normal operating range.
A
> starved plate design would use less. The purpose is to get the tube
> to distort the signal and that can be done at low voltage or high.
> The signal coming out of the preamp is still a line level signal.

No, I understand how a tube works. You need more voltage if you want
to provide more signal current - all other things being equal. 24v is
at the low end of a 12AX7's operating range, so while it is within
the tube's operating range and can be used to generate current to
make a line level signal, it's not the best use of a tube in a
preamp. A high voltage preamp is the key to the vintage Made-In-
America Hammond B3 sound with its AO28 preamp, which Don Leslie's
Leslie tube amplifiers of that era were made for.

Manufacturer's trick people into thinking they're getting "the real
deal" by saying the magic words "tube preamp" when the buyer doesn't
understand there is a difference between low voltage "starved plate"
tube preamps and the normal high voltage tube preamps found in those
walls of amplifiers that used to populate the back of rock concert
stages back in the classic rock era. Jon Lord wasn't playing through
Marshalls with starved plate tube preamps.

> There is also more info in the manual that can be clicked to on the
> bottom of the page.
> The 3300 sounds great to me. If you are trying to do a commercial
for
> Speakeasy, why not just talk positively about their product and not
> try to knock their competition.

Well that's what it always seems to come to is the "Speakeasy
Commercial" theory. When players are talking about buying Hammond
Suzuki 3300's and the subject is the preamp, it seems like a good
time to recall there is an honest alternative to the 24v preamp, and
it comes with a horn and rotor too :)

I use a SE 122/AMA as the preamp/amp modeler for my solid state
Leslie Proline 760.

Walter j



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