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400+ sideways

Discussion in 'Amps and Cabs [BG]' started by REME7178, Oct 7, 2013.

  1. I was just wondering if, I were to use my Mesa Boogie 400+ sitting sideways in a rack would it screw it up? I mean screw it up at all long term, short term, is it working harder sideways, or anything. Is there any benefit to having it sitting flat? I stow it sideways when it's not in use, should I not do that? It's built like a brick crap house, so I am just about sure that everything's fine with it sideways. someone just planted a seed in my head like, "Oh, you keep your amp sideways?", but when I said "Yeah" dude was like a fricking cricket. Put my mind 100% at ease guys and let me know, so I can sleep at night.
  2. The tubes don't care what position they are in, but, operating the amp on it's side is NOT how the ventilation was designed. The upper output tubes will see much higher heat than the bottom ones. I would imagine the Mesa chassis is strong enough to not be bothered about storing it on it's side. I would not transport it that way though, iron transformers are really heavy.
  3. Yeah.

    Iirc the fan in mine blows air in from the outside. Sideways, either the fan works against the general thermal flow, bad, or it works with it, also bad because the top rows of tubes will be living in a superheated airstream.
  4. Ok, so? It's bad. Got it.
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Well with an external fan blowing into the amp you might be able to get around the ventilation issues.

    The tubes in your amp can be operated horizontally or vertically as was pointed out. As far as I know, all musical instrument amp tubes fall into this category.

    In some rare cases, tubes have heater windings that can sag and short if they are operated horizontally. The tube data sheet will specify acceptable tube orientations.
  6. chaosMK


    May 26, 2005
    Albuquerque, NM
    Hi-fi into an old tube amp
    I always felt like with that fan the first few tubes got most of the cooling.

    If you place it on it's side with the fan on the bottom and open up the opposite side of your rack case one way or another so that air can flow/heat can escape it would probably work fine. You can test with your own observations. Stick our hand in etc.

    I ran my 400 for years in a shallow Gator rack case with no special vents, fan on high. Never had an issue. Using my "hand test", I never felt like the temperatures reached an extreme point.

    Buster! doesnt have a fan. It just sits there with the tubes hanging down (it gets hot too!). I've yet to find a guitar amp with a fan. Triple Rec has about a zillion tubes, no fan.

    Here is an excerpt from the 400+ manual:

    If fan noise is objectionable in a recording studio for example - you can turn the fan off without causing overheating unless the Bass 400 enclosure is in a confined space. Use the fan's HIGH speed when the 400 is in an equipment rack with other units and free air circulation is reduced.
  7. LiquidMidnight


    Dec 25, 2000
    Indeed. The tubes next to the fan can be almost cool to the touch, but the ones further down the line are noticeably hot. I've always ran my 400+ with the fan on its highest speed. One time after doing some general tube maintenance stuff, I turned the fan off and forgot to turn it back on come gig time. Yeah, it sounded good for about five songs before it started overheating. :oops:
  8. Look at the tubes farthest from the fan. Horizontal amp. Those tubes draw case air to them as they heat the air above and it rises, recirculating and mixing with fresh outside air.

    Now put the amp on its side, fan on bottom. Fresh air comes in at bottom. The bottom tubes heat it and the ones above heat it some more. You create a hot baked chimney of air rising up. That would not be a good thing for the amp.

    I don't think the tubes themselves care about their operating temperature so much. They are the hottest part, not much difference between red hot and really red hot. I'd say it's their heat getting into the rest of the electronics that does the damage. Mounting tubes under seems like really dumb design. :confused:
  9. I think I am good, I got the external blowing around the of the rack case circulating the air. I can't even really here the fan running. Maybe I just got to get rid of some stuff, or spread my gear out so I can set it normal again. Thanks all.

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