[hdjim69]

Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

Thanks
J

[tubegarden]

hdjim69 wrote:
Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

Thanks
J

Hi RATs!

OK, just plug some in and listen. The 12AX7 you like are the good ones.
They are all individuals, in this physics controlled reality, but, some
may tickle you in a strange and exciting way. Or not. Just try and hear
what you hear. There are many things that can make you feel foolish or
special. 12AX7 labelling may or may not make your list ... listen and
hear. Theoretically, all will work in a 12AX7 circuit ... but if you
like one better than the others, you need not explain why to anyone.
Just enjoy

Happy Ears!
Al

[Phil Allison]

"hdjim69" wrote in message
oups.com...

** Groper alert !


Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?


** 12AX7s are classed as audio "pre-amp' tubes - becaue they have very
little power handling ability.

Even when used in a power amp, they function as a voltage pre-amp for the
output tubes.





........ Phil

[Ian Iveson]

hdjim69 wrote

Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see
some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they
also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

A good general resource, including valve specs and subs:

http://www.duncanamps.com/

Probably called a preamp valve because it is widely used in the preamp
section of guitar amps. Similarly for domestic amps, they are usually
used for the input, voltage amp stage.

We don't know what yours are used for...

cheers, Ian

[hdjim69]

A good general resource, including valve specs and sub

Thanks all, I'll do my 'studying up' and if I get the tubes I'll post
my findings...

J

Ian Iveson wrote:
hdjim69 wrote

Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see
some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they
also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

A good general resource, including valve specs and subs:

http://www.duncanamps.com/

Probably called a preamp valve because it is widely used in the preamp
section of guitar amps. Similarly for domestic amps, they are usually
used for the input, voltage amp stage.

We don't know what yours are used for...

cheers, Ian

[Chris Hornbeck]

On 16 Jan 2007 18:20:50 -0800, "hdjim69" wrote:

Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

No. Also,

WA and WB once meant something, a military ruggedness spec,
but nowdays mean nothing but advertising.

The good news is that you'll probably never have to replace
a 12AX7 if you keep it away from your hammer collection;
their work factor is very low. Don't worry so much.

All good fortune,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Peter Wieck]

Chris Hornbeck wrote:

WA and WB once meant something, a military ruggedness spec,
but nowdays mean nothing but advertising.

The good news is that you'll probably never have to replace
a 12AX7 if you keep it away from your hammer collection;
their work factor is very low. Don't worry so much.

Yes and yes.

However, look for a Sylvania Mil.Spec. 5751 instead of that 12AX7. I
believe you will be well pleased with it at a small fraction of the
cost of even an indifferent 12AX7. They are distinguished by green
brand printing and sometimes green stars. They were made in uncounted
millions for the Military and today remain a ~$5 tube. In my
experience, they blow the socks off of any 12AX7, Telefunken or
otherwise.


Thusly:

http://www.wiwitubes.com/pic/tube/SYLjan5751.jpg

Peter Wieck
Wyncote, PA

[Claudio Bonavolta]

hdjim69 a écrit :
Hi, I'm new to tubes and I have a pair of monoblock power amps each
with a single 12AX7 tube. I want to pick up some spares and I see some
on ebay but they have a WA or WB extension, eg 12AX7 WB and they also
specify preamp. Are these different tubes than a 12AX7 for a power
amp?

Thanks
J

As others already told you, these tubes are used either in preamps or
input stages of power amps.
They should normally all be compatible but there may be exceptions
depending how the tubes are used.
As another poster told you, you can easily hear differences between
tubes, so try as many as you can.

If you need an introduction to audio tubes, there's a beginners section
on this page:
http://www.bonavolta.ch/hobby/en/audio/audioel.htm
Together with a bunch of schematics and other infos on the subject.

Claudio Bonavolta
http://www.bonavolta.ch