PRRI Harshness?

Discussion in 'Amp Central Station' started by vashondan, Sep 14, 2020.

  1. vashondan

    vashondan Tele-Holic Silver Supporter

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    I've got a PRRI with a Celestion Gold in it and play a Tele with a Seymour Duncan humbucker in the next. Have always loved the combination. Sweet and full. The last couple of weeks its been sounding harsher to me and no matter what I do with the amp settings I can't get my sound back. What could cause this kind of change? Tubes? New strings on the guitar? I'm also getting a little bit of squeal from the amp and what sounds like a crackly sound intermittently. I'm grasping at straws here. What do you think?
     
  2. tele-nova

    tele-nova TDPRI Member

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    Squeal and crackle would indicate to me you need new tubes
     
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  3. xtelesquirex

    xtelesquirex Tele-Meister

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    Sounds like you need new tubes.
     
  4. vashondan

    vashondan Tele-Holic Silver Supporter

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    Ok, two for two! Thanks for the responses.
     
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  5. Wally

    Wally Telefied Ad Free Member

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    A tube problem would be the simplest problem. First, is one or both power tubes redplating? If so, that is a problem and it is tech time,imho.
    If the problem is there with the reverb switched out, then Using a 12AX7, sub it in V1...does anything change? If not, put the original tube back in and sub for the V3, which houses one triode that is the third gain stage. Does anything change? If not, use the sub tube in the V4 position...one triode I; the tube is the cathodyne phase inverter. If noth8ng changes, then one could suspect the power tubes. One test there would be to quickly touch a power tube for part of a second without burning the flesh. Touch the other power t7be....is the heat felt in the two tubes comparable? Is one tube cold? If a tube is cold, then it is not 9neucting signal, and this situation would result in some nasty distortion.
    If the tubes seem to be functioning properly, do you have another speaker arrangement through which you could run the amp? A bad voice coil that is dragging yields a nasty Sonic.
    Is the amp still in warranty?
     
  6. vashondan

    vashondan Tele-Holic Silver Supporter

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    Thanks for your response Wally. The first power tube is burning brighter than the other. I can see red at the top and the bottom ( theres a black band in the middle so can't see) while the second one is slightly lit at the top of the tube. If it is redplating are you saying that it's more than replacing tubes and therefore needs to go to a tech? Could you describe what you mean by the reverb being switched out?

    I don't have any tubes to substitute(?). I do have another of the same speaker that I can switch in though.
     
  7. Wally

    Wally Telefied Ad Free Member

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    Vashondan, reverb switched out means that the reverb circuit is grounded out an will not function....the footswitch takes the reverb in and out of the circuit. If the noise is there with the reverb out, then the noise more than likely not related to the reverb circuit.
    Here is a picture of a redplating power tube. Any small spot of red on those long dark elements, which are the plates, is a problem. Redplating is a sign that the tube is drawing too much current for some reason or other. Imho, the amp might need to be in a tech’s hands. It is possible to replace the power tubes and fix the problem. However, if something inside is out of whack that is causing that one tube to draw extra current then it takes tech work to fix it. And...imho, rebiasing is necessary when returning those power tubes.
    Do you have a picture of the power tubes in operation.
     
  8. vashondan

    vashondan Tele-Holic Silver Supporter

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    Thank again. I’ll take a pic after my dentist appt!
     
  9. Wally

    Wally Telefied Ad Free Member

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  10. vashondan

    vashondan Tele-Holic Silver Supporter

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    IMG_1714.jpg IMG_1713.jpg
     

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  11. Wally

    Wally Telefied Ad Free Member

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    vash9ndan, I don’t see evidence of redplating. The long, dark elements are the plates and are the dominant feature we see there. The orange glow there are the heater filaments. The tubes look different because the two tubes are not the same make of tube.
     
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  12. Hey_you

    Hey_you Tele-Holic

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    Makes me wonder if it could be a connection problem. Cord? Jack?
     
  13. AxemanVR

    AxemanVR Tele-Afflicted Ad Free Member

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    If you have a tube amp you should always have spare tubes.

    I’d get a matched set of four tubes, that way you know they will easily swap out if one goes bad


     
    Last edited: Sep 15, 2020
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  14. vashondan

    vashondan Tele-Holic Silver Supporter

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    I did find that the nut for the instrument plug was loose and so is the pick up selector. I don't think though that they would cause the harshness or the squealing. Ill play with it some more and maybe switch out the speaker next weekend.
     
  15. JDRNoPro

    JDRNoPro Friend of Leo's

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    I say try replacing the tubes. As stated above, you should have spares anyway.
     
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  16. vashondan

    vashondan Tele-Holic Silver Supporter

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    I did just order a set.
     
  17. vashondan

    vashondan Tele-Holic Silver Supporter

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    Thanks for all your help.
     
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  18. Wally

    Wally Telefied Ad Free Member

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    Did you buy this amp used? one wonders how the two different power tubes ended up. Usually we run power tubes of the same make and the tubes are matched for performance. This is not to say that tubes from different manufacturers should not be used in this manner, but one would still like them to be matched to some range of operation.
     
  19. vashondan

    vashondan Tele-Holic Silver Supporter

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    Bought it new. I can't remember if I had at some point put in new tubes. The amp has performed beautifully until recently.
     
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  20. Wally

    Wally Telefied Ad Free Member

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    Odd that is. I would guess that at some point someone installed a replacement power tube. The 6V6 with the Fender logo on it is likely an original tube for the amp. The other is not original.
     
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