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Can you have too much sound deadener?

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Can you have too much sound deadener?

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First off, hello to all of you. 

Now, I have a 1987 Dodge Dakota with a Sony CDX-GT700HD CD Receiver, Polk dxi 5x7"s and 5 1/4"s.  I am also using a 10" dxi sub powered by an Infinity Beta Digital 100 amp.

I am needing to know, can you could  use too much sound deadener?

Currently, there is dynamat in the doors and on the floor.  Every spot has been sprayed with multiple layers of canned deadener (even inside the rear pillas.)  Obviously this has been needlessly spendy, however, that isn't the real problem.

There is absolutely no bass coming from the door or  rear speakers.

Just curious as to whether or not I should remove some.

Thanks.

Verified Answer
  • No.

    If the Polk's are being powered by the head only, they are extremely under-powered. Also, if you do not have the Polk's highpassed at a frequency above what the sub is lowpassed at, there might be frequency cancellation and/or phasing issues that can really affect the low-end sound.

    GLH Geeked

  • J Ro
    i will say that the purpose of any deadening material is to transform acoustic energy into heat.  for SPL, this is not desirable.

    I agree, but what the OP is doing isn't really sound deadening, it's damping. Deadening materials like Sonex convert acoustic energy into heat, and can have an effect on SPL. Dynamat and sprays like Pro-Coat can help control resonances, stiffen panels a bit and lower ambient noises, but they are not much more effective at turning sound into heat that the metal they are applied to. They may control the dissipation of energy that would escape through the door panels and floorpan anyway, but they don't really absorb energy and convert to heat it like Sonex.

    Damping and reinforcement can help one improve sound quality by taking certain variables out of the mix. Deadening materials go beyond that to absorb energy.

         RESIma

All Replies
  • No.

    If the Polk's are being powered by the head only, they are extremely under-powered. Also, if you do not have the Polk's highpassed at a frequency above what the sub is lowpassed at, there might be frequency cancellation and/or phasing issues that can really affect the low-end sound.

    GLH Geeked

  • Hi. Welcome to the forums. I concur with GLH. Sound deadening isn't causing your problem.

    So much of it may be slowing down your truck, but it won't limit your bass. Smile

         RESIma

  • It also depends on what you are trying to do with the sound deadener.  Are you trying to decrease the level of road noise or deaden the panels of squeaks and rattles?  In trucks 2 of the areas that let a large amount of road noise in are the roof and the back of the cab behind the seats.

    • Pioneer DEH-80PRS
    • Kicker ZX700.5 5ch amp 4x90w + 1x570w
    • 12" JBL P1220 Factory Ported Enclosure
    • 2-12" Polk Audio DXI-124 Custom Ported (soon)
    • Polk Audio dB651 6.5" & dB 691 6"x9"
  • While I don't believe his sound deadening is to blame (not entirely at least), too much, or poorly placed sound deadening can hinder bass response. Yes, it really can, believe it or not. If you ever talk to guys who are in SPL competitions that use sound deadening, they'll put some in, measure their output, put some more in, measure again, and every now and then after putting some in it will decrease their SPL and so they'll go in a remove what they just put in to gain bad that lost SPL. Then go placing more on other areas repeating the whole process. At least I've seen people do this process and actually loose some output, but as I said, they end up removing what they just place so as to regain the lost bass.

    I can't believe his sound deadening has sucked all the bass response out of his speakers, but it could be a contributing factor.

  • Weigel21
    While I don't believe his sound deadening is to blame (not entirely at least), too much, or poorly placed sound deadening can hinder bass response

    i'm with Weigel on his theory here.  deadening and strengthening are too different things entirely, and an SPL competitor wants to 'strengthen' not 'deaden'.  10 layers of DynaMat will never accomplish the same thing as a steel I-beam welded to the rear package tray, but they both do serve to reduce rattles.

    obviously there could be a much more simpler problem such as incorrect phasing, and the OP needs to explore that.  try moving the balance all the way left/right and see if it increases the bass.  same with the fader... all the way front or rear.  and if none of that helps, reverse the phase on the sub.  if no difference is noticeable between your sub being normal and reversed, than you have a more complex issue.  reversing the sub makes it 180 degrees out of phase with a 'normal' setting.  if your sub is 90 degrees out of phase with your cabin speakers, reversing it will make no audible difference... it is still 90 degrees out of phase!  that means cancellation, which is no good.  fortunately, crossovers will shift the phase more slightly, so adjusting the crossover may make more of an obvious difference since you're only shifting the phase 20 or 40 degrees, instead of 180.

    basically if anything other than dead center on fader and balance has more bass, you have a phasing issue.  the fix to this is easy, just reverse the speaker wires (pos and neg) on one speaker.

  • since the question is more about deadening, i will say that the purpose of any deadening material is to transform acoustic energy into heat.  for SPL, this is not desirable.  the object in SPL is to increase dB's, not reduce them.  a brick-walled basement is probably the best environment for SPL gain, but a vehicle with very sturdy reinforced panels (like a bank truck) also works well.  any flexing in the sheet metal or windows is transmitting sound outside of the vehicle.  you can slow it down with acoustic dampening, or you can contain it with structural bracing. 

  • J Ro
    i will say that the purpose of any deadening material is to transform acoustic energy into heat.  for SPL, this is not desirable.

    I agree, but what the OP is doing isn't really sound deadening, it's damping. Deadening materials like Sonex convert acoustic energy into heat, and can have an effect on SPL. Dynamat and sprays like Pro-Coat can help control resonances, stiffen panels a bit and lower ambient noises, but they are not much more effective at turning sound into heat that the metal they are applied to. They may control the dissipation of energy that would escape through the door panels and floorpan anyway, but they don't really absorb energy and convert to heat it like Sonex.

    Damping and reinforcement can help one improve sound quality by taking certain variables out of the mix. Deadening materials go beyond that to absorb energy.

         RESIma

  • it would be SO much easier to take you seriously if you would just say "dampening."  do you have a similar hang-up as me where i refuse to use caps in forum posts bcuz i hate capacitors?  or is this one of your mental jokes?  i'm not getting it... hopefully you will clarify soon.

    deadening absorbs sound, structural bracing increases it (on the side of the bracing that the sound originates, i.e. the interior of a car with a sub). not even sure if you're arguing this point or not, but just wanted to clarify for the benefit of future readers.

  • Sorry buddy, but "dampening" involves getting things wet. For example; "Dude, we were at this car stereo competition and they were dampening all of the girls tee shirts".

    "Damping" describes how oscillations in a system decay after a disturbance. For example;  "Dude, we were at this car stereo competition and a guy had his car so well damped that there were no rattles anywhere".

    Deadening is the absorption and conversion of energy, damping is the controlled dissipation of energy that would somehow dissipate anyway.

    Not arguing, just chiming in.



    [edited by: Alex W at 11:31 PM (GMT -5) on Sat, Feb 18 2012]

         RESIma

  • Alex W
    For example; "Dude, we were at this car stereo competition and they were dampening all of the girls tee shirts".

    Now that's dampening properly.

    In any case, please excuse my backward ways in using the term "dampening" when referring to reducing annoying vibrations in vehicles. I graduated with GED, so I don't know no better. Crying

  • dampen means to increase wetness, dampening also means the act of increasing wetness.. pretty much the same thing.  the rules don't apply the same for google dictionary as they do with car audio, however.   these terms actually have a specific use in the industry.  far as car audio goes, the term "dampen" describes transferring acoustic energy into heat.  its a good thing, but i'm not even sure if we're arguing here or not cuz i'm just confused by your answer... please elaborate!

     

  • Weigel21
    please excuse my backward ways in using the term "dampening"

    Now don't go all damp on us, we're cool with it.Cool



    [edited by: Alex W at 12:11 AM (GMT -5) on Sun, Feb 19 2012]

         RESIma

  • J Ro
    these terms actually have a specific use in the industry.  far as car audio goes, the term "dampen" describes transferring acoustic energy into heat.

    Not arguing at all.

    I think the industry has simply bastardized a scientific term. It happens all of the time, in a lot of industries. Damping is a very specific scientific term that relates to attenuation, logarithmic decrement, and Q-factor, among other things. It is not related to thermo-acoustic power conversion, which is what "sound absorption" materials do.

    The next time you're talking about this stuff use "damping" to refer to the dissipation of energy and "deadening" to refer to the absorption/conversion of energy. If anyone challenges you, bet them the drink of your choice. Order Louis XIII. Their eyes will be dampened and their voices damped.



    [edited by: Alex W at 11:58 PM (GMT -5) on Sat, Feb 18 2012]

         RESIma

  • Alex W
    The next time you're talking about this stuff use "damping" to refer to the dissipation of energy and "deadening" to refer to the absorption/conversion of energy.

    we're spiraling down into a vortex of semantics, and even if we reached a conclusion on what the correct terminology is, i doubt ppl will adopt the same wording.  the terms deadening/dampening are used interchangeably, and incorrectly, but there's no way to stop it.  it's a mad world!

     

  • As long as this thread is totally sidetracked....J Ro, did you used to have a different username? You really remind me of someone who used to post on here a few years ago.