Tube Layout Chart for MT15?

Choo Choo Boogie

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Mar 3, 2019
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I put a JJ EC81(12AT7) in V3 and gave me more useable gain.....not as harsh.
I tried a Tung Sol 12AX7 in V1 and got a more Marshall-like sound.
I currently have a Ruby 12AX7AC5 HG+ In V1 and love it.....sound is between a Marshall and a Diezel VH4....to me anyway.....
 

Brennen

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I tried a Mesa AT7 in the Pi slot, also tried it in V2 and V3. It does drop the gain a little bit in the V1&2 but I'm a high gain guy so went back to the 12ax7's. The feel of the gain response in the Pi slot made it feel "flatter" in response if that's any help. For lower gain users I think this is great for sure.

Also dropped $40 on a Genalex premium 12ax7 and...Just a recommendation get something half price lol. I compared with a Mesa 12ax7 and the tone difference in negligible at best
 

DreamTheaterRules

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Also dropped $40 on a Genalex premium 12ax7 and...Just a recommendation get something half price lol. I compared with a Mesa 12ax7 and the tone difference in negligible at best
That is a very highly rated tube for new stuff. What slot did you put it in?
 

Brennen

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I ended up removing it and saving it. That being said, I got this amp for the gain and also play a baritone in Drop G# so my opinions don't always translate especially when the thread was more about seeing a gain reduction. In addition the amp is fairly new so the stock tubes are also still quite new. Next will be an EL34 swap, I had them replacing the 6L6's in my Triple Rectifier and loved them.
 

vchizzle

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First time looking at swapping tubes here. Call me dense, but V1(input) is located next to the input jack like most amps, right? The chart appears opposite. Standing at the back of the amp with power tubes closest to you, it shows the loop tube to the left of the power tubes rather than to the right of them(as it is on the actual amp).
 

Cortez09m

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First time looking at swapping tubes here. Call me dense, but V1(input) is located next to the input jack like most amps, right? The chart appears opposite. Standing at the back of the amp with power tubes closest to you, it shows the loop tube to the left of the power tubes rather than to the right of them(as it is on the actual amp).
Yes V1 is in front of the input, then V3 (2nd stage) and V4 (3rd stage). Then V2 (clean) and V5 (loop). The single that sits toward the power tubes is V6 (Phase Inverter)
 

Srini

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Nov 6, 2017
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Hi all, I just stumbled on this topic while researching recording amps. The MT15 sounds about perfect except for the aggressive metal character (I know, that's saying love the car except for the engine). I've done this kind of thing before years ago with a Mesa Studio preamp, and a 12AU7 (you read that right) smoothed it out to a gorgeous blues recording amp. So, my question is, since V2 and V3 are the Lead "gain" tubes, does V2 correspond to the Gain knob and V3 to the Lead Master knob? Or vice-versa? In that case, wouldn't it be better to swap out V2 instead of V3? But people here seem to find the V3 swap to provide a better gain sweep. Perhaps best to change both, eh?
 

Ascension

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Apr 27, 2012
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The effects driver is the last tube in the line to the left looking at the front of the chassis or V5 not V6. Thought the same thing as the chart here is saying but it's wrong. Have both a MT 15 and a Archon the Tube functions are the same in both but the Archon lists the PI as V5 and the Effects drive as V6 go figure from the charts that PRS gives you.
From PRS
https://www.prsguitars.com/documents/mt15_tube_chart.jpg
 
Last edited:

Goran Lorencin

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My gosh and fudge ... it looks like I had it all wrong, was thinking that the V1 was the first from the left when looking at the amp from the front. And as it turns out it is the first from the right, nearest the input jack ... is that correct?
 
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