Marshall VS265R - 12AX7 Recommendations?

[Scottie]

I have an old-ish (1998) Marshall Valvestate combo and an wondering if
anyone here has tried replacing the preamp tube in one of these (or
other Marshall Valvestate) to achieve a warmer tone? I currently have a
crappy Sovtek 12AX7 in the preamp and it sounds COLD!

I realise that this is not going to change the fundamental
characteristics of the sound. I own an Orange Class A tube amp and
fully realise that no change of preamp tube will ever make the Marshall
sound -that- sweet...

I have heard of a few people using JJ or Groove Tubes 12AX7's in this
kind of amp, who have reported favourable results. Just wondering if
any of you amp gurus here would have any recommendations for different
brands/variants of the 12AX7 that might help this amp to warm up a
little...

Cheers

Scottie

[anybody-but-bush]

Scottie:

I tried changing the tube to a 12AU7 and 12 AT7 to get
a little less gain. Sounded worse. I also put a few
different 12 AX7's in it and the sound was IMHO the
same. I think the circuit has more to do with the sound
of this amp than the tube itself. It is running off a
pretty low voltage and current and will never sound
like a class A bias tube with a high(er) voltage and
large(r) plate resistor. But I am no expert.

The best thing it did for that amp was put a 100 watt 8
ohm wire wound resistor with screw tap on it in the
back between the speaker and the amp. The tap is about
3/4 the way toward the ground side

amp +
3/4 of the resistor
Tap goes to the speaker +
1/4 of the resistor
amp - goes to the speaker -

Now I can crank the volume and gain without blasting
the amp. It cost like seven bucks from Newark
Electronics. I think about 90 % of the amps power goes
to the resistor and 90 % of the tone goes to the
speaker.

Phil


----- Original Message -----
From: "Scottie" <***@gmail.com>
Newsgroups: alt.guitar.amplifiers
Sent: Sunday, November 07, 2004 9:55 PM
Subject: Marshall VS265R - 12AX7 Recommendations?


: I have an old-ish (1998) Marshall Valvestate combo
and an wondering if
: anyone here has tried replacing the preamp tube in
one of these (or
: other Marshall Valvestate) to achieve a warmer tone?
I currently have a
: crappy Sovtek 12AX7 in the preamp and it sounds COLD!
:
: I realise that this is not going to change the
fundamental
: characteristics of the sound. I own an Orange Class A
tube amp and
: fully realise that no change of preamp tube will ever
make the Marshall
: sound -that- sweet...
:
: I have heard of a few people using JJ or Groove Tubes
12AX7's in this
: kind of amp, who have reported favourable results.
Just wondering if
: any of you amp gurus here would have any
recommendations for different
: brands/variants of the 12AX7 that might help this amp
to warm up a
: little...
:
: Cheers
:
: Scottie
:

[Scottie]

Hey Phil,

well, the problem isn't that the Sovtek has too much gain, I think they
are generally pretty cold and ugly-sounding tubes. If anything, maybe a
little more gain wouldn't go astray (I'm only talking about the clean
channel here - I don't use OD1, and OD2 has more gain than most other
amps I've ever played) just to make it sing a bit...

Surely a lower-gain tube would make it sound even colder still? Please
correct me if I am wrong in this...

I am tempted to try to get hold of a Mullard or something of that ilk,
but worried that I might be forking over $$ for something that either
won't work or will work differently to how I imagined.

Since it's a pre-amp tube, the amp volume shouldn't make a huge
difference to the tone, should it?

Scottie

[anybody-but-bush]

"Scottie" <***@gmail.com> wrote in message news:***@c13g2000cwb.googlegroups.com...
: Hey Phil,
:
: well, the problem isn't that the Sovtek has too much
gain, I think they
: are generally pretty cold and ugly-sounding tubes. If
anything, maybe a
: little more gain wouldn't go astray (I'm only talking
about the clean
: channel here - I don't use OD1, and OD2 has more gain
than most other
: amps I've ever played) just to make it sing a bit...
:
: Surely a lower-gain tube would make it sound even
colder still? Please
: correct me if I am wrong in this...
:
: I am tempted to try to get hold of a Mullard or
something of that ilk,
: but worried that I might be forking over $$ for
something that either
: won't work or will work differently to how I
imagined.
:
: Since it's a pre-amp tube, the amp volume shouldn't
make a huge
: difference to the tone, should it?
:
: Scottie

A lot of people hear "big" differences in tubes. The
comparison is usually the new tubes to the old tubes
being removed from the amp. The circuit the tube is in
makes most of the difference in the sound that comes
from the amp. Pushing the tubes current up IMHO is what
makes the euphonics appear. Putting a tube in a
transistor amp is kind of a half assed attempt to get
the tube sound in the amp. Generally they run the tube
at a low voltage and current just to save on heat and
maintenance costs.

Phil

[Scottie]

Hmm, good point about the low voltage. How does one push the current to
the tube up?

Maybe I'll just see if I can get hold of a reasonably priced EH tube
instead of chasing around for a Mullard and spending a small fortune to
acquire it...

Would anyone even consider modding the preamp circuit on a Valvestate
for a smoother sound? Would that involve just modding or would you
replace it entirely with another preamp section? I ask this because I
really do love the seething metal distortion that the OD2 channel on
this amp produces and would like to keep the amp for this reason... but
the clean channel is just... cold.

As you can probably tell, I am a rank amateur when it comes to tube/amp
knowledge, so any wisdom is fully appreciated..

Cheers,
Scottie

[anybody-but-bush]

----- Original Message -----
From: "Scottie" <***@gmail.com>
Newsgroups: alt.guitar.amplifiers
Sent: Wednesday, November 10, 2004 2:07 AM
Subject: Re: Marshall VS265R - 12AX7 Recommendations?


: Hmm, good point about the low voltage. How does one
push the current to
: the tube up?

Either a lower plate resistor or a higher B+. Raising
the B+ a bunch and raising the plate resistor not so
much will do.
:
: Maybe I'll just see if I can get hold of a reasonably
priced EH tube
: instead of chasing around for a Mullard and spending
a small fortune to
: acquire it...
:
: Would anyone even consider modding the preamp circuit
on a Valvestate
: for a smoother sound? Would that involve just modding
or would you
: replace it entirely with another preamp section? I
ask this because I
: really do love the seething metal distortion that the
OD2 channel on
: this amp produces and would like to keep the amp for
this reason... but
: the clean channel is just... cold.

Now I realize that I have the VS 65R not the 265.
here is the resistor in the back
Loading Image...
Phil
:
: As you can probably tell, I am a rank amateur when it
comes to tube/amp
: knowledge, so any wisdom is fully appreciated..
:
: Cheers,
: Scottie
:

[anybody-but-bush]

"Scottie" <***@gmail.com> wrote in message news:***@z14g2000cwz.googlegroups.com...
: Hmm, good point about the low voltage. How does one
push the current to
: the tube up?
:
: Maybe I'll just see if I can get hold of a reasonably
priced EH tube
: instead of chasing around for a Mullard and spending
a small fortune to
: acquire it...
:
: Would anyone even consider modding the preamp circuit
on a Valvestate
: for a smoother sound? Would that involve just modding
or would you
: replace it entirely with another preamp section?

This amp is not set up to modify easily. Unlike a lot
of vintage amps that are point to point wired or use a
piece of fish paper with eyelets the Valvestate amps
use a PCB and it is not easily disassembled and
re-assembled. Most mods would be done by snipping out
the components from the PCB and attempting to solder
the new parts to the stubs remaining on the PCB, not an
optimal mechanical mod. NOt a beginners project.


I ask this because I
: really do love the seething metal distortion that the
OD2 channel on
: this amp produces and would like to keep the amp for
this reason... but
: the clean channel is just... cold.
:
: As you can probably tell, I am a rank amateur when it
comes to tube/amp
: knowledge, so any wisdom is fully appreciated..
:
: Cheers,
: Scottie
: