Control Cavity Cover Materials

Discussion in 'Luthier's Corner' started by KeithAlanK, Jul 18, 2016.

  1. Is there any consensus on what to use, from a purely sonic viewpoint?

    Here's my dilemma:
    I have a problem bass (Ibanez Iceman ICB200 Korea) with bad neck-dive that currently has over a pound of lead inside the control cavity as well as attached to the strap. Luckily, that huge plank of mahogany is kinda thin and light, so even with the lead it's not heavy, just awkward and uncomfortable.

    In the future I'll be making a strap button extension to cure it for good, but on a whim last week I made a new control cavity cover out of 16ga steel, primered and painted satin black to match the plastic original.
    The new piece weighs 5.5 ounces, compared to the original's almost nothing, so it allowed me to remove a bunch of lead.......but I was expecting a change for the better in tone and/or sustain.

    You see, back around 1985 when I was a guitarist I built a preamp from plans for my Ibanez Artist 2619 (think double cutaway Les Paul with lots of abalone inlays) and to adjust it's DIP switch I made a clear plexiglas cover with a little hole so I could poke a small tool in there and change settings.
    Sustain went right into the toilet! It was a HUGE difference, and that plexi plate didn't last half an hour.
    Put the original steel one back on, and that guitar sang again.

    Expected similar results with this Iceman bass, which was already the most lively, bouncy, sustain-monster I've ever owned. Surprisingly, quite the reverse happened. In fact, I would say it's 20-30% deader than before.

    My best guess is that the heavy steel plate is dampening the body's ability to resonate.
    Because my old Artist guitar had a thick maple top with a mahogany back, maybe it was better suited to a heavier material?

    Perhaps a thin gasket or soft washers could isolate the steel plate a bit, and restore some of the lost sustain?

    Have any builders examined this topic in depth and published their findings? Steel, brass, aluminum, this wood, that wood, plastic types 1-17, composites, sandwiches...Has anyone done some serious testing to see what the effects can be?

    I would love to hear theories and experiences on this topic.
    I'm so surprised by this--after having just enough real-world experience to form an opinion decades ago--that now I'm afraid to replace this bass's plastic output jack plate with a proper gold-plated steel one.

    Thanks for any and all input.
  2. personally: I would extend the strap button and remove all unnecessary weight.
    charlie monroe likes this.