Members rockinroller Posted January 30, 2008 Members Share Posted January 30, 2008 I have a couple of Yorkville XM200 bass combo amps that I use in live performing. I installed side handles on them yesterday and after cutting out the templates to fit the 6x8 handles (but before installing them) I tried the amps out to make sure I reinstalled the speakers correctly, etc. after removing them for cutting. I was surprised to hear how much low-end was missing with those side handle cut-outs open to reveal the inner cavity of the bass cabinet. I re-inserted the wood cutouts and the low end returned. My question to all of you is: When I had the amp opened up, I noticed a large cavity area behind the front-facing speaker that is obviously part of the acoustics of the cabinet. However, I wanted to get your opinions regarding whether I should install insulation material into that cavity in the hopes of creating more "thunder" in the low end and eliminating or minimizing internal distribution of the sound before it has a chance to project out through the speaker. Or is that open cavity area all part of the design of the cabinet to already achieve maximum output, bass, or whatever it was intended to do? Thanks! Link to comment Share on other sites More sharing options...
Members Roguetitan Posted January 30, 2008 Members Share Posted January 30, 2008 insulation is only going to absorb any sound waves I dont think adding insulation to a cabinet is a good Idea unless you are trying to muffle any sound waves coming out of the cab, JMO Link to comment Share on other sites More sharing options...
Members guitargod0dmw Posted January 30, 2008 Members Share Posted January 30, 2008 insulation is only going to absorb any sound waves I dont think adding insulation to a cabinet is a good Idea unless you are trying to muffle any sound waves coming out of the cab, JMO Plus, it will change the internal volume of the cab...thus making it less efficient. When you cut out holes in the cabinet, sound waves were escaping from them...that's why you were missing low end. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 30, 2008 Moderators Share Posted January 30, 2008 Here's what happened. When you cut holes in the cabinet, you added two ports. That tuned the cabinet to a higher frequency than it had been, causing your loss of lows. Adding insulation will increase the effective cabinet volume, making it more efficient, not less. However, it will also change the frequency response. This might very well result in it sounding less loud than before. It will also reduce internal standing waves, which could also make it less loud. If the cabinet is sealed, adding insulation will give the cabinet a smoother response. It will give it more low end extension, but it might not be audible. Your amp might not be producing those frequencies in the first place, or the increase might not raise the lows into the audible range. If the cabinet has a peak in its response, this will be reduced. As such peaks are always in the audible range, this could make the cabinet sound less loud than before. If the cabinet is ported, adding insulation will make the overall effective volume larger, but also could reduce the efficiency of the port. If you add insulation to a ported cabinet, make sure that the port is not blocked by the insulation. Unless, of course, you like the resulting sound. This is for music production, after all, not high fidelity reproduction. The internal standing waves will be reduced, but how it will affect the overall frequency response depends on how the cabinet was designed in the first place. It might reduce a peak in the response, or introduce one. It could do both. Link to comment Share on other sites More sharing options...
Members thelurker Posted January 30, 2008 Members Share Posted January 30, 2008 Isaac has touched on it pretty well. Insulation is added to increase the effective volume of the cabinet. I wouldn't add anything to a cab you're happy with. It can increase the volume by as much as 10%, IIRC, causing it to act unpredictably. Link to comment Share on other sites More sharing options...
Members rockinroller Posted January 30, 2008 Author Members Share Posted January 30, 2008 Sounds good, thanks for the advice. It appears that "if it ain't broke, don't try to fix it" is a good adage to apply in this circumstance. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 30, 2008 Moderators Share Posted January 30, 2008 Theoretically, it can increase the volume by up to 40%. In practice, 25% is achievable, but 10%-20% is more common. And "if it ain't broke, don't try to fix it" is almost always good advice, but, in this case, anything done is easily undone, and all you're out if it doesn't help is the cost of the insulation. Link to comment Share on other sites More sharing options...
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