Rivera M-100 -- Noise problems

Discussion in 'Amps and Cabs' started by MattT, Mar 18, 2006.

  1. MattT

    MattT Member

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    I just got a Rivera M-100 head today, and while it sounds good for the most part, there are some pretty major noise issues.

    When the master volume of either channels is turned up past around 3, there is quite a bit of hum. But thats not the worst part. When the reverb is on , there is a waterfall type swooshing sound, and it increases as the knob is turned up, and at around 5 it becomes unbearable.

    Anyone know how to fix this? I dont think there should be this much noise, since most reviews say its dead silent.

    :BEER
     
  2. riverastoasters

    riverastoasters Member

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    My first guess is that you have a tube that isn't happy.

    The M-100 should be dead-ish quiet. Not quite as quiet as later Rivera designs because M/S series (and TBRs) still use AC filaments. All the later models use DC filaments.

    But that is pretty minor in terms of noise. A properly functioning M-100 should be very quiet indeed.

    The reverb waterfall sound might be a microphonic tube. If it is a preamp tube you can check that by putting each tube, one at a time in V2. This is described in Richard Johnson's page:

    http://bellsouthpwp.net/r/i/ricjohns/Rivera Preamp Tube Guide.htm#Microphonics

    or you can use a pencil eraser to tap the tubes, as described here:

    http://www.rivera.com/accesstubes.php
     
  3. Ben C.

    Ben C. Member

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    I'm not sure about the hum (I had an M60, M100, Quiana, Rake, and 100 Duo 12) but the reverb 'waterfall noise' is normal. I went through several tube brands and types in that slot, and they all made a decent amount of noise... my solution was eventually to keep the reverb below '3'. And I never really use reverb anyway. Yea, that was annoying though. It almost sounds like you have the gain channel cranked... that hind of hiss.

    -Ben
     
  4. hawkeyeinexile

    hawkeyeinexile Silver Supporting Member

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    also, you can always call Paul Rivera and ask him or Mike the Tech or someone else @ Rivera. add'l note: i've had quite a few Riveras, incl. a couple M100s, an S120, and i still have a BM100 combo - none of them made that waterfall noise.

    :cool:
     
  5. MattT

    MattT Member

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    Thanks guys, I will check out the preamp tubes. And the hissing doesnt only happen when the gain channel is cranked. Even when I turn the master up on the clean channel it starts to do it. Also, I've noticed even when I just turn the amp on, coming out of standy, there is a relatively loud hum that doesnt go away no matter what knobs I turn.
     
  6. riverastoasters

    riverastoasters Member

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    Maybe a microscopic amount, but "unbearable"? I just this minute checked with my Jake. No attenuation, nothingin the efx loop. Modern mode. Channel 2 (clean). Ninja Boost engaged. Volume: 8, Treble, Mid, Bass all at 5. Master: 8. Presence: 7. No input. Stock Jake speaker GT12-75T.

    Now the Reverb noise shows up, but not really until it's up to 8 or 9, and then it was well below conversational level - nearly dead quiet until the Reverb was past 5. Now with the Volume and Master at 8 and Modern (55 Watt) mode with boost engaged, we're talking a very loud setting, and a lot of Reverb.

    The noise is not that sensitive to the Volume setting - because there is not much internal noise for the preamp. The Presence control accentuates it - which is not surprising - the noise seems to be coming from the reverb.

    If I had a lot of this noise, I would consider it a problem. In the settings I actually use for this amp, this noise is inaudible. Getting a lot of hum with either master past 3 is not OK with me either. I have quite a few Riveras, and they are all very quiet, some of them ARE "dead quiet" as people like to say.
     
  7. riverastoasters

    riverastoasters Member

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    I would check the power tubes and their bias. I'm way far from a tube amp repair guru, but I wonder about your EFX/Reverb driver (V4) and your phase inverter (V5). I would check all the preamp tubes.

    The stuff you are having issues with so far sounds to my "first aid" level thinking like things that can be explained by bad tubes.
     
  8. riverastoasters

    riverastoasters Member

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    MattT PM'd me that his noise problem is solved, but he didn't say what the solution was.
     
  9. riverastoasters

    riverastoasters Member

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    Hey MattT don't keep us all in suspense, what was the issue?
     
  10. Phil M

    Phil M Member

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    I would be almost certain that it was 1 or 2 of the preamp tubes. I've had some not-so-great luck with amps in the mail, but it's almost always just a preamp tube that went bad in transit (or was bad to begin with).
     
  11. Roe

    Roe Member

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    check the manual - it says something about getting rid of noise
     
  12. myles111

    myles111 Member

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    When was the last time the output set was changed and the preamp tubes checked?

    What output tubes are currently in the amp and where is the bias set in milliamps?
     

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