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Preamp & poweramp on top of cabs?

Discussion in 'Amps and Cabs [BG]' started by Gnobility, Jul 10, 2004.

  1. Gnobility


    Aug 13, 2003
    I'm using an Ampeg SVP-Pro & QSC RMX 1450 poweramp into Avatar 1x15 & 2x10 cabs. I've had the cabs off in the far corners of the basement and the amp rack by me next to the drummer, but I'm gonna move the cabs and stack them over where I stand so I can hear the marvelous nuances of my playing, rather than waste it on my guitarist & trumpet player.

    Question for ya's - my bandmates advise against putting the preamp & poweramp on top of the cab stack because they figured the vibration will eventually get the best of the amps. Makes sense, I suppose - but combo's seem to deal with the vibration OK.

    What do you all think?

    Gn :meh:
  2. lbanks


    Jul 17, 2003
    Ennui, IN USA
    I'm not sure about damage, but the rack case rattle is too loud to ignore.
  3. if crossover circuits inside a speaker cabinet dont rattle apart why would the things in the rack case? I think just taking you rack to a gig does alot more damage than it sitting on a cabinet and get a massage of vibration.
  4. natrab


    Dec 9, 2003
    Bay Area, CA
    It is just another stress on the connections in your amp. Just like moving it, driving with it in your car, kicking it etc. It's not going to kill it or anything. However it's one of things where if you don't need to do it, why do it (kinda like hitting your head on the wall. It won't kill you but why?).
  5. Arthur U. Poon

    Arthur U. Poon

    Jan 30, 2004
    SLC, Utah -USA-
    Endorsing Artist: Mike Lull Custom Basses
    I've wondered the same thing. To be safe, I put a piece of foam between my rack and cab.
  6. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    DFW, Texas
    If you've ever sat on a cranking good bass cab you'll get an idea of how much shaking your stuff on top will get.

    My wife made me a slip cover out of black canvas into which I put a piece of polyester (sp?) padding and a waffled piece of foam rubber. They are just the right size to cover the bottom of my rack rig.

    I'm a bit OC, but my pre (like yours) has tubes. If there is any tendency towards microphonics, vibrations will just make things worse (shorten the usable life of your tubes).

    I doubt well-made modern SS stuff would be much affected by this type of vibrations, but I would probably put a pad under it just to be anal (I mean "safe").
  7. Lockout


    Dec 24, 2002
    I like having my rack up off the floor so I can see it and make adjustments to it more easily, but I don't like stacking it on top of my cab because of all the vibrations. I don't want to be buying new power tubes again any time soon.

    Someone needs to make a rack case with retractable table legs. That would be nifty.
  8. Sufenta

    Sufenta Trudging The Happy Road of Destiny

    Mar 14, 2002
    The Signpost Up Ahead.
    Auralex www.auralex.com makes some MoPAD isolation wedges that I use between my cabs and rack. They work perfectly as does the GRAMMA isolation pad that my cabs sit on. You can get these at GC or through musicians friend.
  9. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I suppose it's possible. But I've been running my PLX/BBE 383 combination in an SKB case on top of my EV cabinet for about six years, about twice a week on average. I've had no failures, rattles, intermittants, et al.
  10. inazone


    Apr 20, 2003
    yup, I think you will be fine by just setting it on the cab but Im anal (safe) and use a gramma pad. :eyebrow:

    btw, when I set a plx 3402 on the cab it rattled, when I use the gramma, it doesnt.
  11. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Never had any problems running my Eden or Demeter preamps and various power amps in a rack on top of my cabs, with lots of weekly practices and gigs, some at very high volumes, over the course of about 7 years.

    The latches on the rack itself rattled sometimes, which was annoying but fixable.

  12. Big String

    Big String Supporting Member

    Apr 22, 2000
    Northwest Indiana
    Second that. That was my first intention and recommendation for this handy tool quite some time ago. I now use either one of mine on every gig either under my casterless mini cabs or on top of my big rig to isolate the rig from the tremendous bootay.
  13. xyllion

    xyllion Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    Many many people have been setting their amps on top of their cabs for many many years. Could the vibration cause damage? Yea, I suppose it could, but then so can transporting it. I don't know where you are playing, but I rarely have enough space at gigs to spread out. Even when I do, I like having my amp high enough that I don't need to bend down to adjust anything.
  14. LJW


    Feb 8, 2002
    northeastern pa.
    The gear seems to get a rougher ride traveling to the gig than at the gig.

    I put a stadium pad under the rack to be polite.