Tube Layout Chart for MT15?

Discussion in 'Amplifiers' started by DreamTheaterRules, Jul 23, 2018.

  1. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs

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    Anyone seen one? Is it safe to assume it's the same as they Archon?

    Asking for a friend with some new tubes to play with and an itchy trigger finger.
     
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  2. bodia

    bodia Authorities said.....best leave it.....unsolved

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    That ain't all that's itchy :eek:
     
  3. bubbastain

    bubbastain New Member

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    I’d like to know as well. I did try a 12AT7 in V1 and it was pretty cool. Really gave the gain knob a wider sweep. The gain knob at 10:00 is plenty for me so I don’t mind losing some
     
  4. Evil Z06

    Evil Z06 New Member

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    Hey Shawn since you did the tube layout on the Archon.....how about it's little brother....the mighty MT15..I'm assuming it's the same as the Archon minus 2 output tubes?..Thanks
     
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  5. bubbastain

    bubbastain New Member

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    I do know that from right to left it’s V1, V3,V4, V2, V5 and then V6 is one in the middle.. Would like to know the specific function of each though.
     
    #5 bubbastain, Jul 26, 2018
    Last edited: Jul 29, 2018
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  6. bodia

    bodia Authorities said.....best leave it.....unsolved

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    Got this from Customer Service today. These guys rock!

    V1 – input

    V2 – lead gain

    V3 – lead gain

    V4 – clean gain

    V5 – phase inverter

    V6 – effects loop (behind front row of preamp tubes)
     
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  7. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs

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    5751-V2!
     
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  8. elvis

    elvis Hamfisted String Banger

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    Six stages of lead gain. Yikes!
     
  9. Shawn@PRS

    Staff Member Moderator

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    here you go
     

    Attached Files:

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  10. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs

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    Don't fear the beast, my man. Grab it. Tame it. OWN it. ROCK IT!
     
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  11. Yzerman

    Yzerman New Member

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    So if I replace V2 & V3 with a 5751 I should see a good reduction in gain?
     
  12. DreamTheaterRules

    DreamTheaterRules Former Lyricist for Calhoun Tubbs

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    I'd try just v2 first.
     
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  13. Yzerman

    Yzerman New Member

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    Replacing V3 with a 12AT7X does miracles for this amp.... smooths the gain out and helps with the taper. In V2 it was too muddy but V3 was perfect!
     
  14. bubbastain

    bubbastain New Member

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    Just wondering if this is from Right to Left or as labeled on the PCB? On the PCB from Right to Left it’s V1, V3, V4, V2, V5 and V6 behind the front row.
     
  15. Yzerman

    Yzerman New Member

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    The one i replaced was the 4-5 gain stage for the lead as per Shawn's drawing...it should be V3.
     
  16. bodia

    bodia Authorities said.....best leave it.....unsolved

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    This was the first sentence in the email I got from Cust Ser

    I have listed the preamp tubes below for your reference. They are in order looking at the back of the amp, going left to right (starting at the input). You can change the gain with a 5751 (or a 12AY7).

    Shawn inserted a chart in post #9 above
     
  17. Van Noord

    Van Noord New Member

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    THIS!! I did some tube swapping in every preamp spot with a Ruby 12AT7 V3 position yielded the absolute best results. More sweep on the gain dial, and revealed more of the gain's character and feel.
     
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  18. Rooster7six

    Rooster7six New Member

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    Anyone try a 12AT7 in the phase inverter?
     
  19. andy474x

    andy474x Knows the Drill

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    For sure! This is my go-to tube swap when I want to bring the gain down on an amp - and all the PRS amps I've played have plenty of it. V1 could even be a nice spot for one, but it would depend on what the effect on the clean channel would be as well, because one half of the V1 tube services on channel, and the other to the other channel. IMO, every tube amp lover should have a little stash of 5751's to play with. The nice thing about them vs a 12at7 is that spec-wise, the 5751 is more like a 12ax7, whereas the 12at7 is relatively much less like a 12ax7. Tonally as well, the 12at7 sounds much thinner and more harsh than a 5751, in the instances I've tried them. Although, I don't think it will hurt anything to use the 12at7 in an instance where the 12ax7 is stock, as the way the specs work, from what I understand, is that the 12at7 can handle more. It's the reverse that can wear down a 12ax7 faster - I read it on the internet, so it must be true. In the spirit of modding something, I suppose if the 12at7 gives you what you want, and it's not hurting anything, by all means, do it. But I still recommend trying the 5751 in those instances as well, just to see what the differences are.

    Also, while we're on the topic of the MT15 tube chart, I just want to say how brilliant it is that PRS designed an amp that uses all 12ax7's for the preamp, from a maintenance and gigging point of view. You can just have a few extra 12ax7's and a pair of 6L6's on hand, and if anything takes a crap, you don't have to worry about having a whole selection of tubes on hand. Very convenient. It would be extra nifty if they would add some kind of quick access door to the tubes, to make changes speedy. That and the external bias check would truly make the PRS amps a maintenance and gigging dream.
     
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