RE: Tubes in Pre-amps: your expertise and honest opinion.

["William Walker" <billwalker@baymoon.com>]

  Andy wrote;
"Sometimes in this sort of gear, the valve is run at low voltage, which 
some
claim doesn't give the same "valvey" sound, and this is likely to be the
case if you don't see the valve actually glowing.
(clever Behringer use LEDS to simulate the glow )"

I'm one of those "some"...
  One of the reasons I like the sound and feel of my Duncan twin tube 
preamp
is the fact that they opted to use a pair of subminiature tubes (smaller
than 12ax7's) running at high voltage. I've owned tube overdrives before,
chandler tube drivers and the like, but this thing is so much more dynamic
to the touch and rich in overtones than the type of low voltage output
design Andy is referring to. On the other hand, I've also had good luck 
with
my Art pre-amp. I have an old two channel 2 space rack mount model and I
suspect its running at low voltage. I have never changed the tubes in 10
years and that's a good indicator. But any decent preamp to me is a good
thing to throw in front of a DAW if for no other reason than to give a bit
of compression and softening to the signal, and a bit more sonic complexity
before it gets 10101010101010101'd :>) 
Bill

-----Original Message-----
From: a k butler [mailto:akbutler@tiscali.co.uk] 
Sent: Tuesday, January 02, 2007 10:19 AM
To: Loopers-Delight@loopers-delight.com
Subject: Re: Tubes in Pre-amps: your expertise and honest opinion.


>But, as read further i learned that the main benefit
>comes from DH-Set "SE" configurations and that the "PP
>(push-pull)" configurations do substantially less of
>this "warming effect"????
>
>so, i am wondering then, do all current technology
>tubes sound better/warmer then non-tube preamps? or
>are there only certain tubes that do this?
>
>how would i know technically (besides listening) if i
>have a SE tube or a PP tube from specs in my manual
>that read "Tube Type: 12AX7A hand selected"?


here's the techno babble:-


SE= single ended
PP= push pull

Those are 2 different configurations for valve power amps.
It's not a matter of tube type, but how they are connected.
The PP configuration is only used for driving loud speakers.

For pre-amping you'll be using a simple circuit which would (I guess) 
correspond to SE, tho' I don't know if the term is actually used for 
non-power amp applications.

12AX7A is a very common general purpose valve, used in cheap gear and 
very expensive gear.

Probably your cheap pre-amp has a chip to do the actual "pre-amp" 
part of the process, then passes the signal through the valve to 
colour the sound. ( and this is an often used method, even for high 
end audio gear)

Sometimes in this sort of gear, the valve is run at low voltage, 
which some claim doesn't give the same "valvey" sound, and this is 
likely to be the case if you don't see the valve actually glowing.
(clever Behringer use LEDS to simulate the glow )

So:-
Best way to tell is to do what you already did...just listen :-)

andy butler