Amp volume issue

Discussion in 'Amp Central Station' started by Stanford Guitar, May 28, 2020.

  1. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    I have a Rivera Clubster 25 Doce 1x12 tube amp. Lately, when I'm playing the clean channel the volume will spontaneously cut by about 1/2. The dirty channel is not affected. If I switch the amp to Standby, the volume will very briefly increase just before it goes to standby. All tubes were just replaced and biased so I don't think there's an issue there. Could it be the FX loops jacks are dirty? I run effects in the FX loop. Could the Standby switch need cleaning or replacing? Ideas?
     
  2. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    Anyone? Buehler?
     
  3. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    4,137
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    Most switches don't get cleaned as they are sealed units, = but the standby switch wouldn't be related to the issue. You're just hearing whatever is left of the amp signal being used while things shut off.

    If you keep cables in the effects loop it isn't likely to be dirty, but never hurts to plug and unplug the cables a few times.

    Just because tubes are new/recent doesn't mean something couldn't be
     
  4. Wally

    Wally Telefied Ad Free Member

    Posts:
    35,758
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    And....If your amp is similar to the circuit shown for the Rivera Clubster 25/40 that 8 find at EL34 World, that is a solid state input preamp. Your problem may exist prior to the tube gain stages. IF I read that schematic correctly, V1A is the first tube gain stage for Ch2 while V1B is the first tube gain stage for Ch 1. You could sub a Known good 12Ax7 tube into V1 and see if that cures the problem. you could simply have a dirty tube socket there, as well. Pulling and re8nstalling the tube might cure the problem. If you have some contact cleaner, spray the t7be pins before reinstalling it.....pull and reinstall a few times.
     
    Stanford Guitar likes this.
  5. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    4,137
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    Yup - that's the schematic I was looking at too - only one I could find quickly.

    and now that I'm looking at my previous reply....it seems to be cut off before the part where I said "try swapping the 12ax7" for whatever reason.
     
    Stanford Guitar likes this.
  6. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    This one is the Clubster 25 Doce, I think the schematic maybe be different for the Doce vs non-Doce model? I think the non-Doce model is a solid state input? Thanks for looking into this!

    This is the one I have, it's a 1x12": https://www.rivera.com/product/discontinued-legacy/clubster-doce-1x12/

    This is the non-Doce model that is a 1x10" https://www.musiciansfriend.com/amplifiers-effects/rivera-clubster-25w-1x10-combo-amp
     
    Last edited: May 29, 2020
  7. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    Wally, check out my comment above. Thanks for your help!
     
  8. Wally

    Wally Telefied Ad Free Member

    Posts:
    35,758
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Stanford, there are 2x12AX7s in that amp. That matches this schematic...
    https://el34world.com/charts/Schematics/files/Rivera/Clubster_25_45.pdf

    This schematic differs greatly from say the R series that carry 12AX7s but have roughly the same functions, gains, effects. In short, there is no way that your amp can do the things it does and carry only two 12AX7s without doing quite a bit of gain and processing in solid state domain. Unlike the R series, your amp also has a solid state driven and recovered reverb. If I am reading this schematic correctly, one 12AX7 divides its triode for a gain stage in each channel, and the other 12AX7 is the phase inverter.
    The only reason I mentioned this is that each of those channels has solid state components as well as one tube triode each that could fail....and therefore a new tube in V1 may or may not cure the problem.

    In other words, the two amps you list above are very similar despite their differences, as I see it.
     
    Stanford Guitar likes this.
  9. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    Got it, just making sure. This amp is my son's bedroom practice amp. I'm going to clean everything with Deoxit and see what effect that has. One thing I noticed was a cracking sound on the clean channel with the volume on 0, that goes away once the volume is turned up. Replaced the preamp and power tubes, problem still there.
     
    Wally likes this.
  10. Wally

    Wally Telefied Ad Free Member

    Posts:
    35,758
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Yeah.....the only tube that could be at fault only in one channel would be V1. The phase 8nverter and the power tubes would exhibit the problem in both channels.
     
    Stanford Guitar likes this.
  11. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    I just called Rivera, great guys who always answer the phone! and he said to clean all the pots as a first step. The amp is about 15 years old, so maybe some oxidation in the pots? I'm going to go through the entire amp and clean it. It has never been cleaned in 15 years.
     
    Wally likes this.
  12. corliss1

    corliss1 Friend of Leo's Platinum Supporter

    Posts:
    4,137
    Joined:
    Sep 13, 2008
    Location:
    Lansing, MI
    15 years I'd say it's time for a full service anyway.
     
    ce24, Stanford Guitar and Wally like this.
  13. Stanford Guitar

    Stanford Guitar Tele-Meister

    Posts:
    361
    Joined:
    Feb 11, 2020
    Location:
    California
    One thing I've noticed is the volume cut happens right after I engage a pedal. Deoxit ordered, will be cleaning soon.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.