TAD7025WA's vs. Genelex T12AX7:


All the modern Marshalls I have owned came with Marshall-branded Sovteks. Maybe they have changed, as I have not owned a Marshall in a while (a condition I think I need to remedy). In my experience, doing a JJ retube really smooths out the graininess of the high-gain Marshalls and adds some compression, which I personally like.
 
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gball said:
I don't think you would like the result but I could be wrong, I just think it would make the amp incredibly dark sounding.
I would not put one in the PI slot personally, because that's going to change the output section.
I'd say start at V1 and roll them in one at a time and experiment until you get what you are looking for though.
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Very prudent advice here! Read and Heed.
 
gball said:
I don't think you would like the result but I could be wrong, I just think it would make the amp incredibly dark sounding.
I would not put one in the PI slot personally, because that's going to change the output section.
I'd say start at V1 and roll them in one at a time and experiment until you get what you are looking for though.
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Oh, OK! I didn't know that! I'm glad you said that....so we are starting at V1
 
gball said:
I don't think you would like the result but I could be wrong, I just think it would make the amp incredibly dark sounding.
I would not put one in the PI slot personally, because that's going to change the output section.
I'd say start at V1 and roll them in one at a time and experiment until you get what you are looking for though.
Click to expand...

Hey, you know me. If one is enough, I'm predisposed to do them all... :-)
 
I'd think you'd only need one of. Its a matter of trying it in the first couple of positions to find the one that best tames the excessive drive. Personally, I would give the NOS JAN GE 5751 that you linked a shot. JAN means Joint Army Navy, so this is a military spec tube, made by GE. I'm with @gball on the 5751 in the phase inverter position, it would change the output characteristics & I don't think in a way you'd want. When tube rolling, (or modifying an amp in any way) its best done one alteration at a time so the results can be observed & analyzed. Pop a 5751 into position 1 & try it. Put the original tube back in position 1 & the 5751 into position 2 & again check the result. I'm confident that it will be one of these first two positions that does the trick as (without looking at the schematic) I imagine position 3 is final gain stage/cathode follower & believe me, you'd know if the cathode follower was being driven too hard. Hope this helps. Cheers
 
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ivan H said:
I'd think you'd only need one of. Its a matter of trying it in the first couple of positions to find the one that best tames the excessive drive. Personally, I would give the NOS JAN GE 5751 that you linked a shot. JAN means Joint Army Navy, so this is a military spec tube, made by GE. I'm with @gball on the 5751 in the phase inverter position, it would change the output characteristics & I don't think in a way you'd want. When tube rolling, (or modifying an amp in any way) its best done one alteration at a time so the results can be observed & analyzed. Pop a 5751 into position 1 & try it. Put the original tube back in position 1 & the 5751 into position 2 & again check the result. I'm confident that it will be one of these first two positions that does the trick as (without looking at the schematic) I amagine position 3 is final gain stage/cathode follower & believe me, you'd know if the cathode follower was being driven too hard. Hope this helps. Cheers
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Got it. We are going to try the 5751 in V1 and leave the 7025-WA's in 2-3-4.
 
Ok, I just pulled up the DSL40C schematic. As I thought V3 is the cathode follower (tone stack driver) tube, so no 5751 in that slot or V4 (phase inverter) slot, ok. As to V1 & V2, I see that V1A is quite hot compared to say a master volume JCM800 or typical 4 hole Marshall, with V1B being used for the Lead 1 & 2 Ultra (drive) channels. V2A is a warmed over cold clipper feeding into V2B, a cool biased gain stage that all channels run through, clean/crunch included. So as I said before, try the 5751 first in V1, then in V2 to see which best suits your needs. Hope this helps. Cheers
 
QUestion - is there anything to the extra charge for "low noise and microphonics" testing? It seems like I should be entitled to expect that for the price of admission.
 
RVA said:
QUestion - is there anything to the extra charge for "low noise and microphonics" testing? It seems like I should be entitled to expect that for the price of admission.
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The only real way to test for these is to put the tube into an actual amp circuit (in the critical 1st position) & check it out that way. That's what the extra charge pays for. Cheers
 
RVA said:
QUestion - is there anything to the extra charge for "low noise and microphonics" testing? It seems like I should be entitled to expect that for the price of admission.
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I imagine it boils down to someone's time and labor to test and categorize the tubes. Some vendors might not charge for it, by compensating with slightly higher prices to start off with.
 
syscokid said:
Leave it on. The ring dampens vibration. It's the most sensitive tube socket in the circuit.

I have one in my Carvin Vintage 16. The tube has "Westinghouse" in red letters on it, but I think it was made by GE.

View attachment 13765
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When I gave my son the Strat I build, I also gave him a Carvin Vintage 16 to play it through.
He hasn't even begun to learn how to drive it to its full potential yet . These are killer little amps.
 
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