nortynorty Posted June 18, 2001 Share Posted June 18, 2001 Forgive me if this has been answered many times before, I am new to Klipsch and therefore new to this forum On Saturday, I purchased my first pair of speakers in over 15 years. My main speakers used to be KEF 104's, but when I moved, they did not fit in the enclosure I had built. I had to use my second speakers, Boston Acoustics A60 Series II, until the woofer material disintergrated. I was happy for the opportunity to upgrade. The SB-3's were very impressive, using Holly Cole's, "I Can See Clearly Now" to really show them off. In any event, what was a clear and punchy bass in the store was boomy at home. The problem is that the only place I can put the speakers is in an enclosure. I am sure that I need to put some sound absorbing material in the enclosure so the bass does not resonate. I was wondering what you might suggest in terms of material to use and how this should be done, ie tightly packed all around, leave room around the passive hole in the back, stuff the hole with material,should the speaker sit on the material as well etc. I would think that if I can insulate the speaker from the enclosure, I will just get the pure sound from the speaker. This or other suggestions are appreciated. Quote Link to comment Share on other sites More sharing options...
jimbobo Posted June 18, 2001 Share Posted June 18, 2001 Get spikes and the boom will be gone ------------------ My bedroom system: TV: 27" Toshiba CZ27V51 YAMAHA RX-V596 YAMAHA CDC-575 TOSHIBA SD2109 KLF 10 soon to have RC-3 KSW-10 (soon to upgrade to 12) POLK R10 Quote Link to comment Share on other sites More sharing options...
Guest BobG Posted June 19, 2001 Share Posted June 19, 2001 You are correct when assuming it is the added enclosure that is making the bass boomy. Unfortunately, most all acoustic absorbers are designed to work at higher frequencies. To absorb bass, you need something with some size to it. I've used a design with various combinations of fiberglass insulation and kraft paper over 6" deep studs. Even then, what frequencies would you choose to absorb? In this odd case, I would suggest you experiment first with an equalizer even though I generally dislike them. You may find that the best approach and one that will at least provide some greater understanding of where precisely the problem exists. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 19, 2001 Share Posted June 19, 2001 Can you tell us something about the enclosure? What does it look like, what's it made out of, how big are the recesses (?assumed?) where the speakers are sitting (width X height X depth), what else is in it? The SB-3 have rear ports - how much clearence do you have between the backs of the speakers and whatever's behind them? Also, weren't the KEF 104s, like, three feet tall with the coupled internal woofers playing in the internal cavity? They seem a bit, uh, different than SB-3s. ------------------ Music is art Audio is engineering Quote Link to comment Share on other sites More sharing options...
nortynorty Posted June 19, 2001 Author Share Posted June 19, 2001 The enclosure is a laminated wood/fiberboard. The front door has a large opening covered with grille cover burlap fabric. There is approximately 2" on either side of the speaker, 4-5" behind and <1" on top. The top is an adjustable shelf which can be raised .5" or so. Removing the shelf will add another 3" to the top of the enclosure. I have the speakers on the little rubber stick on feet which came with them and they are sitting facing straight with the Klipsch grilles on. The speakers are placed as forward in the enclosure as possible. The "floor" on which the speakers sit is fixed. The KEF's were much taller and didn't fit. There was a tweeter, woofer and a passive radiator. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 19, 2001 Share Posted June 19, 2001 If the back of the unit is one of those heavy cardboard - like sheets that is tacked or nailed on to add some structural rigidity, as opposed to wood, I do have a suggestion. Unfortunately, this is one of those suggestions that you can't evaluate until you try it, it's irreversable, and it involves cutting things up. I'd cut out the back of the unit behind each individual speaker. That is, cut a hole in the backboard about the same size, or a smidge larger, than an SB-3. You won't adversely affect the strength of the enclosure; at least, not much, I've had to do this several times to several different entertainment centers when the TeeVee set I was putting into them was deeper than the unit was - I cut out the back behind the set. I think the bass reflex port is seeing another cavity formed by the enclosure, and this is what's causing the boomyness. Removing the back behind the speakers would fix that. DO NOT ASSUME I KNOW WHAT I AM TALKING ABOUT!!! This is YOUR piece of furniture, and there is absolutely no way to know if this is going to make any damn difference at all without trying it. I'd do it, but then I have a very understanding wife. Another thing that might be worth trying, and might help identify whether the port on the back of the speaker loading the enclosure is what's causing the boomyness, would be to plug the ports temporarily and see how it sounds. If the bass goes from too boomy to being too dry and not extended enough, but loses the boom, I'd take that as at least an indication that cutting out the enclosure's back behind the speakers might help. You can use rolled up socks stuffed into the port tubes to block the ports. Ray ------------------ Music is art Audio is engineering Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted June 19, 2001 Share Posted June 19, 2001 quote: Originally posted by Ray Garrison: You can use rolled up socks stuffed into the port tubes to block the ports. You can also use them to stifle the screams from your significant other (if that's a factor) when she sees you heading for her entertainment center with a power saw! (LOL). Quote Link to comment Share on other sites More sharing options...
bensilb Posted June 20, 2001 Share Posted June 20, 2001 An addition to Ray's post... You may want to try cutting out several holes (maybe 1/2" in diameter) in the back first. This may allow the bass to escape without hacking out the entire back. I agree with Ray though. Try doing when your wife is not home. This way you can cover it up without her ever knowing. LOL ------------------ Sony Trinitron 27" TV Yamaha RX-V1000 JVC HR-S3800 Super VHS VCR Sony DVP-S530D DVD Player Sony Tape Sony CDP-CE345 Cd player RF-3 Main Monster m1.4 Biwire Cables RC-3 Center SS-1 Rear Quote Link to comment Share on other sites More sharing options...
nortynorty Posted June 20, 2001 Author Share Posted June 20, 2001 Based on the comments, it sounds as if you know my wife. Actually, the back portion of the enclosure is the same construction as the rest of the unit (laminate over wood/fiberboard). The sock idea makes sense and is worth a try. I was also thinking of moving the shelf which is currently over the speaker to below the speaker. I would support the shelf with bricks on either side for stability. The speaker will be placed on top of the adjustable shelf and will be in a slightly better listening position. I would use the spikes as recommended by jimbobo and the socks as recommended by Ray and see what happens. I thought perhaps of also adding either some foam or rigid insulation in the enclosure to absorb the sound, but as BobG mentioned, it may only absorb high frequencies. If I can somehow isolate the speaker from the enclosure, I would get a purer sound. I also think I will remove the Klipsch grille and therefore be able to move the speaker forward another .5" - .75". Quote Link to comment Share on other sites More sharing options...
nortynorty Posted June 24, 2001 Author Share Posted June 24, 2001 Here's the update. In order to test the spike idea, I purchased rubber screw bumpers (without using the screws) at Home Depot to put under the speakers. I used 3 on each, they are about 7/8" high. I also put a rolled up sock (glad I found a use for those tube socks) in the back bass port. I put rubber spacers on the shelf support and an old mouse pad under my amplifier (it seems others put decoupling or damping material under their components). The brick idea described above was more trouble than it was worth and putting the shelf under the speaker did not do anything to improve the sound. The shelf remains above the speaker. I also removed the grille cover and was able to move the speakers .5-.75" forward. No changes to the interconnects at this time. Overall, the improvement was noticeable. It is significantly cleaner now and much improved. I will get real spikes and may at some point play around with some foam material for the enclosure to see what that does, but basically I am very much happier. Thanks to you all for your thoughtful suggestions. Quote Link to comment Share on other sites More sharing options...
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