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Speaker wadding

Discussion in 'Amps and Cabs [BG]' started by Moo, Nov 16, 2005.


  1. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    So, after my first frankencabinet project I'm left with a question.

    If my speakers are not sufficiently damped with foam or wadding of some kind what symptoms will I be able to hear when I play them? In other words how can I tell if I need it?

    Feel free to make all the jokes you want ;)
     
  2. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    If you don't have adequate wadding, you will find that when you fire your speakers out of a shotgun, that they tend to make a large pattern. As I understand it the wadding softens the impact from the powder charge so the speakers don't deform before they leave the muzzle.

    As for insulation in a cabinet, it often cuts reflections of sound off the interior box walls, which would normally propagate thru the cone of the speaker out of phase. I usually think of it as sort of a metallic midrange tone.
     
  3. BurningSkies

    BurningSkies CRAZY BALDHEAD

    Feb 20, 2005
    Seweracuse, NY

    It's all much clearer now.


    Will it work with my flint-lock tube head?
     
  4. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    You would of course need 'tube wadding'. It would appear to shoot farther with the same loads, but take awhile to warm up and be subject to microphonics.
     
  5. My cat used to climb through the bottom slot port and into my 1- 18" cab, it provided some extra damping. Unfortunately he would not stay in there very long when I was playing. I'm just happy he didn't try to claw his way out through the cone! :hyper:

    Randy
     
  6. Crockettnj

    Crockettnj

    Sep 2, 2005
    North NJ

    you may want to use a slightly more open choke if you are adding extra wadding.

    also, the addition of a little antimony will itghten things up a smidge.
     
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Insufficient damping results in irregular midrange response. You probably wouldn't notice that it is insufficent, but you would notice if you fixed it. Knowing if you need more is easy, just do an SPL sweep and look for irregular midrange response. Barring that just be sure you have an inch of either foam or polyester batting totally lining the cabinet.
     
  8. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    An SPL sweep is out of the question unless my vacuum has a setting I'm not aware of that will do that. ;)

    So it's kind of an interference thing with some waves being boosted and others crushed but generally only in the mids?

    Thanks Bill for the tech, thanks everyone else for the jokes and the cat story.
     
  9. After my cat stuck her head in the port of my 1810 everytime I picked up my bass she left the room, and my dog still dreads the fact I play bass her head its right at speaker level and for them, their hearing is so much better than us humans I would hate to hear/fell what that would be like.
     
  10. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Problems occur where the distance between internal surfaces within the cabinet are roughly 1/4 to 2 wavelengths. If the longest internal dimension is 28 inches, for instance, that's a quarter wavelength at 120 Hz; if the shortest dimension is 12 inches that's two wavelengths at 2260 Hz. For the average bass cab 120 to 2.26kHz is almost the entire bandwidth of the speaker.
     
  11. specplyrz

    specplyrz Banned

    Nov 11, 2005

    I have a question for you. I recently put more damping material in my 810e. I was surprised to find "minimal" damping and the bottom right 10" speaker was wired "out of phase" with the other seven ten inch speakers!!! Good quality control!!?? :spit:

    My question is, I noticed a clearer, more prominent midrange and highs. The "boominess" is completley gone. The best way to describe the new tone is, clearer. No other way to describe it. I put 2lbs of loose "acoustic stuff", fill in each sealed chamber. Each chamber houses two tens. It has not increased the low end but has made it cleaner sounding.

    The original "damping" was left in the cabinet. It looks like carpet padding material, filling about 60% or so of each chamber. The "baffel" where the speakers are, had no insulation what so ever. One chunk of it had already fallen down from the ceilling of one of the chambers. Dissapointed as to the quality of a 1000.00 cabinet. :rollno:

    So, to the question, why does the cabinet now seem to be so much cleaner sounding, especialy the mids/highs. The low bass seems to be more defined also. Am I now hearing this cabinet WITHOUT the resonance of the cabinet itself? There is more "punch" there now, and a slight , so it seems, tightining of the low end.

    The best way to describe it now is......even...it just seems more even....maybe the proper wiring of the speaker has to do with this, I should of left it as it was to hear the difference but I was so surprised/shocked to see the miswiring, :eyebrow: that I just wired it correctly and continued with the adding of the additional material. I used the "9 volt battery test" to confirm all speakers were wired correctly. You have to look closely, but you can see them ALL move outward. Thats how I found the improperly wired one.

    So, please explain the difference in sound that I am experincing. Thanks.
     
  12. The out of phase driver IMO wouldn't cause what you are hearing, I think its the result of the padding.

    The out of phase speaker was tending to cancel out the equivalent of one of the other 10's at low freqs. Not an exact comparison, but you sort of had a 6x10 there for a while.

    Randy
     
  13. specplyrz

    specplyrz Banned

    Nov 11, 2005
    Thanks steve...I sort of figured that...but shouldn't the cab be a bit louder now? It seems the same volume, only much cleaner.
     
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The out of phase speaker would have canceled the bass response of the driver mated to it, and to some extent the others as well, but that only would account for a couple of dB in an 8x10; in a 2x10 it would have been a totally different situation. Added damping material won't do anything for the fundamentals, and not a lot for the 2nd harmonics for that matter, but the information that your brain processes that determines both tone and pitch lies in the 3rd harmonics and higher, so if you clean those up it seems as if the fundamentals and lower harmonics are 'cleaner' even though they aren't.
    The first place you cut corners is where it can't be seen. I doubt if one in twenty speaker manufacturers properly damp their cabs. One attitude is that you only need to line one of two opposing panels in a cab and that will stop destructive reflections, but that's not true. Any undamped surface inside the cab that can reflect soundwaves back to the speaker cone leads to poor response.
     
  15. specplyrz

    specplyrz Banned

    Nov 11, 2005
    Thank you for your quick reply. My other Ampeg amp, Ba210..
    had only one sheet of the same material in it..on the top only...the bottom and sides were bare. I put self sticking 1" foam damping and it completly got rid of the "Boom". The ba210 is a 2 ten, rear ported design.

    I appreciate you expertise in this field.
     
  16. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    That probably saved Ampeg about fifty cents worth of material and two bucks labor. If only engineers ran the world instead of bean counters and lawyers all cabs would be properly damped and the AccuSwitch would work.
     
  17. specplyrz

    specplyrz Banned

    Nov 11, 2005

    As I post this, I have removed all "acoustic fill" material from my 810e, and am putting 1 inch foam on all bare wood surfaces. Will update you. Thanks for your input Bill. I can be very opiniated at times, but I am ALWAYS willing to at least listen, if not learn. :cool:
     
  18. (and always get the last word in)
     
  19. specplyrz

    specplyrz Banned

    Nov 11, 2005
    I think you haircut is affecting your observation skills. :p