Amp on top of Speakers - Good, Bad, Irrelevant?

Discussion in 'Amps and Cabs [BG]' started by LDV, Aug 16, 2003.

  1. LDV


    Aug 2, 2003
    San Diego, CA
    Is it bad to place the amplifier on top of the speaker cabinet? Will the "vibration" cause the amps components to become less reliable? Any thoughts would be appreciated.
  2. Well look at combo amps design. I can't imagine that the type of vibration coming thru the top of a speaker cab could cause any problems unless maybe you had some loose chassis or housing screws on your amp. There are plenty other reliability issues on a bass rig to worry about than this. Just my opinion
  3. Nick Gann

    Nick Gann Talkbass' Tubist in Residence

    Mar 24, 2002
    Silver Spring, MD
    The whole combo amp thing kinda shows that it wouldn't do anything, but I have heard that doing that with tube amps could possibly damage the tubes if the vibrations are strong enough, or over a long period of time.

    I don't know, I don't think there would be any problems. I personally won't be stopped from putting my amp on my cabs.
  4. Gabu


    Jan 2, 2001
    Woodland Hills, CA
    My SVT400T used to ride an Ampeg B25 cab... That's two 15s. It rattled the head right into the shop. It can happen. Better cabs with more bracing should vibrate less though, I guess.
  5. Vibration is bad for ALL kinds of amps, not just tube. Generally, foam or some other type of shock absorber will sufficiently protect a head on top of a cab.
  6. rok51


    Sep 2, 2002
    Crawfordville, FL
    When I first got my GS112s, I noticed that at certain frequencies, something inside my PLX would resonate. I found that it was the fiberboard cooling tunnel. I used neoprene pads to isolate it and then used the same pads (about 1/8 inch thick) on the floor of my SKB case. I then found a pair of the older Fellowes wrist rests that were a thick, but not overly stiff neoprene covered in fabric, that I place under the front and back of the rack case between it and the speakers. No more resonance and the rack is very happily cushioned.

  7. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    You could just use a towel???

    The Hitchhiker's Guide to the Galaxy has a few things to say on the subject of towels.

    A towel, it says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapours; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the slow heavy River Moth; wet if for use in hand-to-hand combat; wrap it round your head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter Beast of Traal (a mind-bogglingly stupid animal, it assumes that if you can't see it, it can't see you--daft as a bush, but very very ravenous); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough.

    --The Hitchhiker's Guide to the Galaxy on towels
  8. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    The best solution for limiting excessive vibrations is something like the Auralex Gramma. [Also can be used for removing mud caused my funkily constructed stages (or floors).]

    Since I have been pretty tight on cash since having been laid off, I bought a 2" thick square of polyester matting and my wife sewed a black canvas slip cover for it (closed cell foam would probably work better, but this seems to do fine).
  9. Brooks


    Apr 4, 2000
    Middle East
    Back in my gigging days I had a 200W all-valve head that I got used, a JBL 4x12 cab and a JBL 18" Folded Horn. I gigged with that setup for 6 years, average 200 gigs a year, plus daily practice mostly at gig volumes. Sold that setup to a pro who was gigging daily, bumped into him 10 years later - it was still going strong. Head was always on top of the cabs.

    By the way, those valves were at least 16 years old, neither me nor the buyer ever changed them.
  10. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
    From your post, I would say that you are an optimist (with lots of good luck--at least in this particular case).
  11. Bad


    To verify, put your butt on the cab and leave it there for the entire duration of the gig. That pickled feeling is what your electronics get every time.

    I can't leave my butt on my subs for more than a few minutes. My SWR IOD metal panels buzz like hell if there is no isolation between the rack and the sub.
  12. Brooks


    Apr 4, 2000
    Middle East
    Just stating facts..maybe I was lucky, or whatever...or maybe it was because amp was hand made by a guy in Southempton UK and built like a tank.
  13. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    I figured it couldn't be good for the electronics. I once put my cellphone on top of the center of my Carvin head which was on top of one 2x10 cab during a rehearsal... before I knew it the phone was on the floor. The head has a wooden case, rubber feet and everything. Think I'll start using a towel.
  14. LDV


    Aug 2, 2003
    San Diego, CA
    This thread clearly shows divided opinions on this subject. I think I will err on the side of caution and buy a dense foam pad to put between the amp and the cabinet to soak up those vibs. I refuse to put the amp on a table, or God forbid, the floor.

    Thanks to everyone for their thoughts.
  15. Arthur Poon

    Arthur Poon

    Jul 13, 2003
    I'm a bit tight on cash too. My QSC PLX2402/SWR I.O.D. rattle inside the rack when placed on top of my cabinet(s) and this concerns me. Where did you find the foam you're using?
    Thanks- Art Poon
  16. kirbywrx

    kirbywrx formerly James Hetfield

    Jul 27, 2000
    Melbourne, Australia.
    Sitting your head on a few mouse mats and blankets absorbs the vibes and does less damage.

    But in my opinion, it would take a 2x15 or an 18 to do severe damage, and even then, it would take years and years of constant gigging to cause sufficient damage.
  17. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas
  18. Arthur Poon

    Arthur Poon

    Jul 13, 2003
    Thnaks, I appreciate the info. I'd suppose in the arts/crafts section?
  19. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    The Republic of Texas