What Valves

[greeny76]

Hi Another question


I am using a Marshall TSL 122 Combo which I got Secondhand.


The Valves in it look like the normal Marshall Valves, although they do look fairly new.


I was wondering what I could put in to bring the Gain stages down on the second and third channels respectively.
I want to keep the character of the amp without as much gain

any help would be great

Thanks


Wayne

[Underground_Player]

Hi Wayne,

Try 12AT7 instead of 12AX7 preamp valves. Or, to go even lower gain, try 12AU7s. In my experience (swapping between 12AX7s and 12AT7s) there is a danger of 1. it not making as much difference as you'd hoped; 2. that the overdrive sounds less 'open' with the lower gain valves, like how it goes on some high gain amps if you turn the gain knob down too far.

If I was you I think I'd go mad and leave V1 as a 12AX7, and swap the ones after that with 12AU7s. For some reason I think this might cure the lack of 'openness' I've experienced. It's always a risk though - you could just turn the gain knob down a bit!

[gwEm]

interesting thread.

i think alot of it depends on the make of the valves, and i'd like to be more knowledgeable in this area.

anyway, in my opinion the 12AT7 from JJ sounds really rather good, and i'd certinally recommend it myself. but i've also heard other people say what underground player does about the sound of this valve type.

the JJ 12AU7 i experimented with can sound rather muffled and fuzzy when used in a gain stage, however it does sound really awesome as a low wattage power valve. i wonder what make of AU you used? i'd like to try it too...

[fps_dean]

JJs are the smoothest new preamp tubes you can get and are not too gainy either, so they would probably be the best choice for you.  They might just be the best new preamp tubes all around too, between the JJs smoothness and the gain and mids of the Electro Harmonix..

Anyway putting a single 12AT7 or 12Au7 in stage 1 or 2 may be all you need.  I believe stage 1 is a pre-gain stage in the high gain channel and not used in the clean channel so if you want to clean up the clean channel too, replace V1 and V2.

[Bird]

www.eurotubes.com

Send him an email and tell him what you want. They're JJ Tesla tubes. I went with a higher gain stage for mine and it sounds killer.   8)

[HTH AMPS]

If I was you I think I'd go mad and leave V1 as an 12AX7, and swap the ones after that with 12AU7s.

I pretty much go with that suggestion too except use ECC81/12AT7s rather than ECC82/12AU7s - the first preamp stage is used for all of the channels so anything you put in that position will affect all channels.

I'd go for...

* V1 - lower gain ECC83 like JJ, EH or (if you can afford it), Mullard ECC83.  A 5751 would also make a good choice if you want to lower the gain/increase headroom on all channels (an ECC81 would work well here too).

* V4 - this is the phase inverter valve, use an ECC81 here for slightly less 'hair' on the tone and more clean headroom.

I'd personally leave the other valves as ECC83s but you could experiment with ECC81s if you like in the V2 position (don't bother with V3 as this is a cathode follower stage driving the tonestack)

Bear in mind that these changes are likely to be more subtle than you might imagine - think of them as fine tuning rather than reinventing the amp's tone.

 :twisted: