Is there a fix yet for the MT15 noise/hum?

Discussion in 'Amplifiers' started by jisham, Aug 7, 2018.

  1. DreamTheaterRules

    DreamTheaterRules New and improved member

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    Hate to sound like a broken record, but did you check the tubes?
     
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  2. Future Barbarian

    Future Barbarian New Member

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    I checked that they were all seated appropriately and they all looked to be in good condition with no abnormal glow. I don't have any extra tubes to try swapping any out. I may try that when the replacement arrives tomorrow since I'll have both, but if the replacement works fine I probably won't look into it any further.
     
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  3. Future Barbarian

    Future Barbarian New Member

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    This is what it sounds like
     
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  4. Gustavo Posada

    Gustavo Posada New Member

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    Great @Future Barbarian !
    Please do let us all know how it goes with the buzz sound while the amp is powered on and standby is on OR off.
    Also, if you don't mind, could you share the readings on both bias exits?
     
  5. Gustavo Posada

    Gustavo Posada New Member

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    Hi @Future Barbarian !
    I understand now... I see that the Master Volume also controls the level of noise, pre-amp phase.
    1. Do you have the same buzz while amp is powered on and standby off?
    2. Could you try plugging your guitar (no volume) to the Effects Loop's Return and check if you still have the noise?
     
  6. Future Barbarian

    Future Barbarian New Member

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    1. The buzz goes away in standby.
    2. Tried plugging in the guitar in the FX loop return and the buzz goes away. Not sure what that means. However, when I do that it starts picking up some radio station noise.

    I also received my replacement MT15 today and it has the exact same problem. Tried swapping some pre-amp tubes between them to no avail. Guess they're both getting returned. This is some unacceptable QC by PRS. Extremely disappointed in this product.
     
  7. Van Noord

    Van Noord New Member

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    Once I replaced the stock JJ in the effects loop preamp spot with a Sovtek, the idling noise and radio station phenomenon went away.
     
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  8. Gustavo Posada

    Gustavo Posada New Member

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    Hi @Future Barbarian !

    1. This is cool! Mine produces a very subtle buzz that passes to the speaker. Though PRS Technical Service said it's normal... I'm not very sure. But this means that other amps might behave the same.

    2. The noise comes because you are injecting a signal directly into the Power Amp (no volume control) and it might pick up some weird signals because of the high volume.

    > The great news here is that we have chase down the problem to the PRE-AMP (clean, lead or effects loop).
    What @Van Noord mentioned about the effects loop tube is one possibility.

    Make sure you do the same test with the other amp before you send them both.
    It's very odd that both have the same problem in the pre-amp phase.
     
  9. Gustavo Posada

    Gustavo Posada New Member

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    That's great @Van Noord !
    Wouldn't it be better to have a very clean tube there?
    I wonder if even while the loop is not being used, the signal goes through it... mmm... is it V6?
     
  10. Future Barbarian

    Future Barbarian New Member

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    @Van Noord
    Did you experience the same noise as demonstrated in the video?

    @Gustavo Posada
    It is weird that both amps have the same issue. I tried turning off every piece of electrical equipment in my house to try to eliminate anything coming in from there as a source. Using a power conditioner doesn't change anything either. My thoughts are it's filter capacitor noise which I can't do anything about.
     
  11. bodia

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

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    I was at a buddies house a few months ago. He has a Two Rock and a couple of Bogners that exhibit the same thing. He went so far as to hire an electrician for a day to troubleshoot things in the wiring in his house. Turns out that his source of noise came from the little device the local water company installs on water lines so they can get a meter read using wi-fi. Nothing he can do about it.
     
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  12. DreamTheaterRules

    DreamTheaterRules New and improved member

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    Yeah, and there is all kinds of stuff like that around these days.
     
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  13. Black Plaid

    Black Plaid just another Alan

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    Seems like the FCC might have something to say about this. Things aren't suppose to pump out enough signal to interfere with other things.
     
  14. Gustavo Posada

    Gustavo Posada New Member

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    On Thu, Apr 18, 2019 at 11:02 PM Paul Reed Smith Customer Service <[email protected]> wrote:
    Hi Gus,

    From the video we find the background noise to be within spec and in line with that model. The MT15 is a multigrain stage amp and putting something like that in a small style head puts everything in closer proximity and there will be background noise.

    Regards,

    Matt King
    Paul Reed Smith Guitars
    Customer Service
    380 Log Canoe Circle
    Stevensville, MD 21666
    410-643-9970
     
  15. Gustavo Posada

    Gustavo Posada New Member

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    On Mon, Apr 22, 2019 at 10:46 PM Paul Reed Smith Customer Service <[email protected]> wrote:
    Hi Gus,

    There can be a little bump switching out of standby however there shouldn’t be much noise while in standby position. From the video we did not hear anything that seemed out of spec.

    Regards,

    Matt King
    Paul Reed Smith Guitars
    Customer Service
    380 Log Canoe Circle
    Stevensville, MD 21666
    410-643-9970
     
  16. Gustavo Posada

    Gustavo Posada New Member

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    And here is the video
     
  17. Van Noord

    Van Noord New Member

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    No, mine only had a hum when taken off standby. It was louder than a normal amp operation hum. It has since diminished.
    I noticed your noise was only present on the lead channel and went away when you switched to the clean channel?
     
  18. Gustavo Posada

    Gustavo Posada New Member

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    Hi @Van Noord ,
    It is present at both channels, standby off.
    When standby on, the small noise/hum/buzz is gone.
     
  19. Van Noord

    Van Noord New Member

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    Oh sorry I was listening to future barbarians video.
    I don't hear anyting in your video that would cause any concern. Am I missing something or just not hearing it maybe?
     
  20. Gustavo Posada

    Gustavo Posada New Member

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    I guess I need to record it with a condenser microphone :(
     

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