Road case radiation

Discussion in 'Amps and Cabs [BG]' started by Michedelic, Aug 8, 2018.

  1. Michedelic

    Michedelic MId-Century Modern

    That got your attention, didn't it? Probably not what you think; I'll explain. A long time ago, I inherited a pair of stereo speakers from a friend who was moving. Two 10" woofers, plus the mid and tweeter components. The cabs were pretty beat and ratty, so I thought about building new boxes(no wonder he left them behind). As I pulled all the drivers and crossover out, I noticed that each of the bottom 10's had no magnet, just a frame and cone. This was my introduction to passive radiators. I really had little knowledge about the arcane world of stereo/hifi, it was enough to just keep up with guitar/bass gear. It just seemed to me to be a very inefficient way of projecting sound, but, whatever. Now, there have been times where I have seen 2x10, 4x10, and 1x15 bass cabs sitting on full anvil style cases, on their sides, not wheels(and not just sitting in the bottom tray with the wheels). I fully understand the idea of the absence of stage coupling in this configuration, but on the other hand, would a case, laying directly on a stage, act like a passive radiator to some extent, if enough low end frequencies where present(and yes, I get it that there might be efficiency issues)? Surely the foam inside would deaden some of the vibration, but I recently picked up a used road case that looks like it would fit an SVT head. Without the foam inside, it just barely accommodates my TC Electronics RS210. With the foam out, I'm in the process of spraying the interior with that Flex Seal(as opposed to spray-on truck bed liner)to give the cab the minimal amount of cushioning and protect the cab from scratches, although its finish is pretty tough(got the bottom tray done so far). So, am I high to think that the road case might vibrate enough to add to the sound, or is it negligible? With the case having the butt-end down and cab on top, it elevates it(the cab)as if there was another RS beneath, which is handy. Does any interior coating, be it that rubbery stuff or a harder plastic, thwart the vibrations? In a way, I don't see much difference between that and those band pass PA subs, but of course there's no port with a road case unless I just use the top shell(that would theoretically act like a bass drum, right?).
  2. beans-on-toast


    Aug 7, 2008
    I use road cases to elevate cabs and heads. They don’t affect the sound or act as a passive radiator. The case wood is usually too stiff to vibrate. A good cab is not supposed to vibrate much.

    A big old stage certainly can vibrate in a passive way. The results are not good at all.

    The Flex Seal rubber coating will dampen vibrations to some extent. There are products that are designed to do this. One well known one is Dynamat: | Dynamat Car Audio Products

    Acrytech sells a spray on damping material. To know how well the Flex Seal works, you’ll have to try it and see.

    Sound damping coating for inside a speaker cab:
    Sound Damping Coatings Archives - Acry-Tech Coatings
  3. Michedelic

    Michedelic MId-Century Modern

    Yeah, I realize the results would probably be minimal, but I'm not that concerned about stage coupling, unless it creates a problem. The Flex Seal wasn't so much about damping, but to minimize cab scratches from case hardware and wheel rivets and t-nuts poking inside. Now, there have been these goofy things since the 70's... (perhaps a similar unit with more wattage).
    Attached to a road case, you now have something active rather than passive(making the case do double duty, in the interest of bringing one less cab). Or is that folly?
    beans-on-toast likes this.
  4. beans-on-toast


    Aug 7, 2008
    People stand on shaker platforms so they can feel the bass at lower volumes. It does work.
    Last edited: Aug 8, 2018
    Rabidhamster likes this.

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