I have Penta 12AX7A tubes. While looking for a replacements
I found these variations:
12AX7
12AX7EH
12AX7WB/7025
12AX7LP
12AX7LPS
12AX7-C

What accounts for the difference? It also appears that
12AX7 is the same as ECC83... is there any benefit
switching to this type for microphone pre-amp?

Penta 12AX7A - a renamed Dragon? Web site: "The
Penta / Shuguang 12AX7A is made in China by the
Shuguang factory exclusively for Penta Laboratories."

Hi RATs!

The maketing guys that assign them hope they mean more sales ...

Just buy some of whatever you can find and plug them in and listen to each for
a week or two, then pick a favorite.

Happy Ears!
Al


Alan J. Marcy
Phoenix, AZ

PWC/mystic/Earhead

The ecc83 numbered tubes are just a European version of the 12ax7
such asTelefunken and Mullard

Powell wrote:

I have Penta 12AX7A tubes. While looking for a replacements
I found these variations:
12AX7
12AX7EH
12AX7WB/7025
12AX7LP
12AX7LPS
12AX7-C

What accounts for the difference?

The "w" suffix meant that they met some mil spec, long life
or such. But realize that the military was interested on other
aspects of vacuum tubes than high fidelity audio work.

On Sat, 10 Apr 2004 11:42:29 -0400, "Powell"
wrote:

What accounts for the difference? It also appears that
12AX7 is the same as ECC83... is there any benefit
switching to this type for microphone pre-amp?

http://www.rru.com/~meo/Guitar/Tubes/euro-des.html

http://home.wxs.nl/~frank.philipse/frank/tubnum.html

http://www.rru.com/~meo/Guitar/Tubes/usa-des.html

I threw this last one in because it compares different types of
12AX7s, although it's for guitar amp owners. You might find this
useful You should also go to Kevin Deal's site and look up his product
descriptions for the various new and NOS tubes that he carries. Keep
in mind though that he thinks that certain tubes work differently 9and
might be ranked differently) in different applications. You should
email him with the name of your unit and maybe the specifications, if
you know them, because he might not be as familiar with every piece of
studio gear as he is with home audio units.

http://www.rru.com/~meo/Guitar/Tubes/Morris/

Oh yeah, here's another one for guitar amp owners. You might or might
not find this helpful:

http://www.rru.com/~meo/Guitar/Tubes.../tt-12ax7.html

"Robert Casey" wrote in message
...
Powell wrote:

I have Penta 12AX7A tubes. While looking for a replacements
I found these variations:
12AX7
12AX7EH
12AX7WB/7025
12AX7LP
12AX7LPS
12AX7-C

What accounts for the difference?

The "w" suffix meant that they met some mil spec, long life
or such. But realize that the military was interested on other
aspects of vacuum tubes than high fidelity audio work.

"W" stands for wolfram, which is anothe name for tungsten.
Tungsten produces a stronger filament than alloy substitutes.
LP -- low power. Filament designed for low power at the expense of reduced
tube life.
EH -- high power variant, possibly with a stronger plate structure.
"C" -- probably modified for a minor characteristic, such as cut-off
behavior.

For Powell, I would recommend the 12AX7UYA.

Robert Morein wrote:
"Robert Casey" wrote in message
...

Powell wrote:


I have Penta 12AX7A tubes. While looking for a replacements
I found these variations:
12AX7
12AX7EH
12AX7WB/7025
12AX7LP
12AX7LPS
12AX7-C

What accounts for the difference?


The "w" suffix meant that they met some mil spec, long life
or such. But realize that the military was interested on other
aspects of vacuum tubes than high fidelity audio work.


"W" stands for wolfram, which is anothe name for tungsten.
Tungsten produces a stronger filament than alloy substitutes.
LP -- low power. Filament designed for low power at the expense of reduced
tube life.
EH -- high power variant, possibly with a stronger plate structure.
"C" -- probably modified for a minor characteristic, such as cut-off
behavior.

For Powell, I would recommend the 12AX7UYA.

.... and LPS means the tube contains a light lubricating oil? :-p

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects: http://dogstar.dantimax.dk |
+--------------------------------------------+

Fred Nachbaur wrote in message news:DUYdc.7115$2H4.2300@clgrps12...
Robert Morein wrote:
"Robert Casey" wrote in message
...

Powell wrote:


I have Penta 12AX7A tubes. While looking for a replacements
I found these variations:
12AX7
12AX7EH
12AX7WB/7025

12AX7LP
12AX7LPS
12AX7-C

What accounts for the difference?


The "w" suffix meant that they met some mil spec, long life
or such. But realize that the military was interested on other
aspects of vacuum tubes than high fidelity audio work.


"W" stands for wolfram, which is anothe name for tungsten.
Tungsten produces a stronger filament than alloy substitutes.
LP -- low power. Filament designed for low power at the expense of reduced
tube life.
EH -- high power variant, possibly with a stronger plate structure.
"C" -- probably modified for a minor characteristic, such as cut-off
behavior.

For Powell, I would recommend the 12AX7UYA.

... and LPS means the tube contains a light lubricating oil? :-p

Cheers,
Fred


LOL!
Actually,for the Sovtek tubes LP means "long plate" and the LPS
variant is the "Long plate,spiral filament" mostly for reducing hum on
AC filament power,and it works pretty well.I've got a few pairs of the
LPS tubes,and I like them alot. ;-)

Hey Fred ,

... and LPS means the tube contains a light lubricating oil? :-p

Wich kinda snake produces that ;-)) ????
Maybe Pat can catch one to try it !! There are lotsa snakes downunder !!

Ronald .



Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects: http://dogstar.dantimax.dk |
+--------------------------------------------+

12AX7 - Original RCA design
12AX7EH - 12AX7 made by ElectroHarmonix
12AX7WB/7025 - 7025 is low hum audio tube, W means military
12AX7LP - Long Plate - marketing - basically a normal 12AX7
12AX7LPS - Long Plate Spiral Filament - due to hum problems with
normal LP
12AX7-C - Don't have any idea


What accounts for the difference?

Some, such as 7025 are legitimate differences in design, the rest are
basically the result of manufacturer's trying to make their product
stand out in a field of very similar products.

It also appears that
12AX7 is the same as ECC83... is there any benefit
switching to this type for microphone pre-amp?

ECC83 is a euro 12AX7, and you will find the same tubes with either or
both labels on them.

Your best bet for a mic preamp, is to buy 12AX7s of any type, which have
been selected for low noise operation, and low microphonics. The price
will be higher, but the results will be worth it.