No announcement yet.

Insulating a 4x12 cabinet pros and cons


  • Time
  • Show
Clear All
new posts

  • Insulating a 4x12 cabinet pros and cons

    I have a 4x12 straight lead Marshall cabinet.  The speakers are closer together than a standard 4x12 cabinet and can actually be carried by one hand. 


    What would the pro and cons on insulating this type of cabinet be?


    Thank you

  • #2

    Do you mean adding some sort of 'padding' or 'buffers' inside the cab?

    What do you think would happen? what are you trying to accomplish?


    Think of a closed-back cab as a balloon and the spkrs as fingers pushing on the balloon. The air in the balloon pushes back on your finger the same way the air in a cab pushes back on the speaker.

    Another factor is how the speaker cone inter-plays with the freqs bouncing around inside the cab. While every frequency can affect the cone,while there is no hard rule- it is usually the lower ones that have the most effect.

    As the cone moves back and into the cab it encounters more resistance the further is tries to go...this can change what we hear out front. (it is usually at higher volumes that we notice these things) The sound wave bounces off the internals of the cab and if it bounces into the cone as it is moving forward it may enhance or even add a whole new frequency to the cone. Making certain notes louder or making overtones that may or may not be pleasing to the ear. If the sound wave hits the back of the cone as it is moving into the cab it may diminish or even cancel out certain freqs. this would make some notes quieter or non-existant. Again, this may or may not sound pleasing.


    All of that to say this, it depends.


    Each spkr and cab are different (even of the same brand/model)...and what volume and even specifically what type of music is being played all are factors. If you fill the are space to make is smaller and/or add buffers to change which freqs bounce back to the cone, you are adding to the equation.

    Being careful not to loosen any wires, experiment.

    Taylor T3/B - Fuzz Factory - Fulltone Clyde - MXR flanger - Flashback - Egnater Rebel 30 112- Mesa vertical 2x12


    • HKSblade2
      HKSblade2 commented
      Editing a comment

      Many big cab co's add padding to rear of cabinet. Supposed to reduce standing waves ala loud speakers for hifi, but you don't need to fill the whole thing. A thin 1/2" or 1" layer of dacron or even carpet padding material is plenty. Some say it makes the cab tighter in lows and low mids. 

      Some say it adds higher freq. BS imo, guitar cab will only yield highest freq of the drivers used. Maybe they confuse presence with depth. IDK. I had a Bogner cab I took the foam off the back. I liked it better with. You don't need to fill the cab and sides. Rear panel is good enough. I have seen some fully padded even around the connection cup and handle cutouts. It doesn't need weatherproofed LOL! 

    • groovy13
      groovy13 commented
      Editing a comment
      Just looking to make it a bit tighter sounding---I mainly play metal and the marshall cab material is particle plywood junk im sure

  • #3

    i overdid it (w/fiberglass) on an old fender 2x12 cab because i thought cab sounded too boomy.  well, i deadened it to the point of muffle.  recently i took out at least half of what i put in, and cab sounds much better.  so if you do it, don't overdo it...

    acoustics and electrics of different aspects. some amps and cabs
    and a multifx...


    • #4

      acoustic insulation on the inside of a speaker cabinet increases it's percieved "volume" and reduces standing waves to prevent destructive interference. the cabinet will be less resonant, but with a cleaner low-end response and a flatter response throughout the frequency range.


      this may or may not be desireable for guitar cabs. the cab overall will sound dead and lifeless, but it depends.


      • #5
        pros-deadened sound, less resonation

        cons-deadened sound, less resonation
        -For Sale:
        -set of GFS Dream 90s- gold and black pearl- $40 shipped in the cont. US
        -(2) Celestion G12M-70 16 ohm guitar speakers in good condition $40 ea. + shipping.
        - Vox VT15 Valvetronix very clean - $85 + shipping
        - Hughes Kettner Edition Tube 20 (the early Voxy sounding one) Sounds & looks good. $250 + shipping. SOLD
        - Crate Palomino V8 - 10" Celestion - Very clean - on Ebay (sold)