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Amp *advise me* buy new, or modify old?

Discussion in 'Amps and Cabs [BG]' started by DanAdams, Jan 18, 2014.

  1. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    I can't really deal with comparing every amp at guitar center, that place just gives me a head ache. and fan noise isn't a spec that is ever mentioned on sheets, plus that place is loud enough that I might not even hear it there.

    So I have what is now about a 20 year old Peavey t-max.
    I'm very happy with it except the cooling fan is ALWAYS on full speed. Does anyone know of a themostatic auto fan switch I could install in this?
    Do you think it might still run too hot even when playing quietly?
    Would installing a potentiometer on the fan power leads provide viable safe control if I'm careful to turn it back up when playing loudly?
    Am I nuts for considering such a modification?

    If that idea is nuts could you recommend a good used >$400ish amp that meets the following requirements.
    -2 or 3 rack spaces
    -not too heavy
    -ample power to play with a loud drummer via a 2-10 & 1-15 (both 8 ohms running together in mono / parallel at 4 ohms)
    -great sound
    -low or no fan noise at low volume!!! (utmost importance)
    -a decent compressor would be nice, but not a requirement

    Thank you, and I'm looking forward to your input.
  2. Marton


    Sep 20, 2005
    GK 700RB-II can be picked up for less than that, and they are awesome little amps. No comp though, but you can probably get the amp + a stombox comp for $400.
  3. Pilgrim

    Pilgrim Supporting Member

    Why is "fan on" a problem? No one will ever hear it when you're playing. You're trying to fix something that's not broken.

    Heat is the #1 enemy of electronics. I have no problem with a fan that keeps the head cooler.

    Or go after a used Genz-Benz Shuttle 6.0 or 9.0.
  4. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
  5. The fan is loud enough to hear while you play? wow. It maybe defective (the fan) and just be noisier than it should be... My 1974 SVT has a fairly loud fan but you cannot hear it at even quiet playing levels, however the thing does sound like a turbine during startup...

    My thoughts; you are either playing at VERY low levels to be able to hear the fan (replace fan with quieter one or replace amp), or you are annoyed by the fan even though you can't hear it while playing (get used to it).

    Looking at your first statement about choosing a new amp I am going to guess you just don't like hearing it so it seems you need a new fan or a new amp... or adjust your attitude about the fan, it is unlikely anyone can hear it but you.
  6. in the studio? put it in another room.
  7. That T max is honestly a pretty good amp, I would just replace the fan or something.
  8. Mortom27


    Jul 22, 2013
    Charlotte, NC
    +1 on the GK700RBII or the 1001RBII
    U can find either one for around $400 or less on guitar center or ebay
  9. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    I agree, I think this amp is good. I bought it new in the early 90s and I have not compared it to anything else since. Since the 700rb is so highly regarded, I may bring my T-max to a shop and compare the two.

    I just found this place
    I think I will try to determine what the CFM on my current fan and try to find a replacement.

    Seriously, I think if any of you heard the fan in person you would agree that it is too loud. With that said I am a recording engineer, so I am sensitive to the noise floor.
    And there ain't always an extra room to put an amp in :)
  10. experimental bassist

    experimental bassist

    Mar 15, 2009
    Good move to replace the fan.

    You may find that a new fan may be much quieter than your current one for a numbers of reasons (old age, design, bushing failure, etc)

    I have an old Peavey F800B head that has a fan that is always on. Although I bought that head exclusively for playing live outdoor shows, if I were to want to record with it or use it for low volume situations I'm sure I would notice the fan and question the need to be always on, as my other fanless amps are dead quiet in such situations.

    My thoughts would be lower volumes equal less heat, so even disconnecting the fan could be an option, although an option with obvious risks.

    Good luck.
  11. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    There are low noise fans available but you would have to be certain that the new fan will adequately cool the amplifier. If it doesn't you'll be shopping for a new amp. The new fan will need to be of the correct voltage and equal or exceed the CFM rating of the old unit.
  12. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    A good clean might help the noise, it always helps amps, might be its choked with dirt that is spoiling the airflow, making turbulence noise and making it run hot enough to keep the fan on. Pretty sure they should be controlled.
  13. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    OK, the lid is coming off tonight. I'll check the voltage with a multimeter, and check for dust, debris, mounting issues, etc.
    If I'm lucky the fan will have CFM data printed on it.

    I did notice an old GK 800rb on craigslist for 200 bones. I know back in the day those were tops. Flea always used them. Quiet? I don't know.
  14. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Paintbrush, toothbrush and vacuum cleaner.
  15. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    The 800RB is convection cooled therefore no fan.
  16. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    I'd add a breathing mask too. You just don't know what the amp has sucked up over the years. Do the work outside if you can.
  17. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    on an unrelated note would anyone have any advice on what I might want to try as a replacement for the stock 20yo no name brand 12ax7 pre-amp tube?
    I have always liked the solid state preamp a bit better, but maybe I just need a juicier tube.
  18. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Hoover means most dust doesn't go everywhere like spray duster.

    For replacement valve, cheap Shuguangs, as rebranded by Ruby, TAD, Groove tubes etc. work just fine, but if you want serious valve rolling, a used tested Mullard or something isn't loads to buy in the scheme of things.
  19. DanAdams

    DanAdams Supporting Member

    Nov 3, 2013
    I used a hoover, I'm not diggin in deep with a toothbrush. I've broken enough gear by digging in too deep, so I'm not fixing what ain't broke.
    The fan is a 115v AC model, I was able to track down a data sheet on it and ordered a replacement which seems to be of similar specs but boasts of a lower noise... I'll see.
    I wish it was a dc fan. It would easier to adjust the speed without adding electronic noise that way, but oh well.
    I'll order another tube just out of curiosity and I will assume it won't change much. I just see it as a sales gimmick. SWR was hot, so Peavey tried to steal some of their thunder.
    Thanks everyone.
  20. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    There are what they call ultra quiet fans. I use a 4530Z made by EBM-Papst when I need an AC, 120mm fan that you can't hear at all. They make other sizes.

    I find that a shaving brush is a useful tool for cleaning amps. In addition to the fan itself, dust needs to be removed from any sensors and other components in the fan circuit. It is possible to disassemble some fans and clean them. This could make it work quieter.

    By the way, the schematic for one revision of the T-Max is available here.

    For recording, sometimes you can get away with using an power switch on the fan to turn it off and blow air form a quiet desk fan into the amp. You have to be careful when doing something like this. Check the amp to make sure that it is being cooled adequately.