RF-7s need cabinet dampening?

[rockbobmel]

I read in some thread before that the RF-7s were lacking bracing and dampening material. I looked in mine and the egg foam stuff is just stuck in there. I rap on the side of the cabinet and can hear a definate resonance as there is no bracing inside.

I came across this stuff..... Blackhole 5 visco-elastic foam and mineral.... well, check it out http://64.233.161.104/search?q=cache:2R7en44425UJ:speakercity.com/Merchant2/merchant.mvc%3FScreen%3DCTGY%26Store_Code%3DSC%26Category_Code%3Ddamping+Blackhole+pad&hl=en&gl=us&ct=clnk&cd=3. Whaddya think?

[Jay481985]

The rf-83 are braced in the middle as I ran a stud finder in it so inbetween the middle of the 20 inch front to back there is bracing but it still resonates if I tap. Also my white foam (its not egg crate shaped just foam inside is just placed and not really glued in or has fallen off.

[rockbobmel]

If I remember right, there was not a big concern. But there is so much hoopla about cabinet resonance. Did you check out what B&W does?. Way out! Multi ply, rounded and multibraced.

[Jay481985]

and basically alot more money. Sure you and klipsch can do that but that would mean running cam routers all day and night making those pieces.

Remember equivalent in size and such klipsch = ~ 5 times more money for b&w.... and sometimes its like some exotic companies, they do it cause they want to be different, if you look at perspective of cost per benefit B&W many trendy things are not so beneficial.

[rockbobmel]

I agree, but would $50. worth of mineral foam benefit the enclosure? Would you notice it?

[Jay481985]

wanna do a funny but ugly mod?

clean the top surface, place a scrap wood on top of the rf7 and then place like 4 cinder blocks on it. Then get a nylon rope and apply tensions on the side to reduce resonance [] seriously

[Raider]

I read in some thread before that the RF-7s were lacking bracing and dampening material.   I looked in mine and the egg foam stuff is just stuck in there.  I rap on the side of the cabinet and can hear a definate resonance as there is no bracing inside.

I came across this stuff..... Blackhole 5 visco-elastic foam and mineral.... well, check it out http://64.233.161.104/search?q=cache:2R7en44425UJ:speakercity.com/Merchant2/merchant.mvc%3FScreen%3DCTGY%26Store_Code%3DSC%26Category_Code%3Ddamping+Blackhole+pad&hl=en&gl=us&ct=clnk&cd=3.    Whaddya think?

 

I have used Black Hole 5 to for damping a cast aluminum cabinet used in a pair of Linaeum LX5 speakers from Radio Shack which were very resonant. After treating the surfaces with BH5, the enclosure was absolutely dead, as though the cabinet was made of a solid piece. Black Hole 5 is self adhesive and easy to use. I think the combination of the self adhesive barrier layer, in combination with the constrained layer barrier septum is particularly effective. Black Hoie 5 addresses a broader frequency spectrum than most competitive products, and will also provide damping for mid and high frequencies as well. With the multiple drivers used in the Reference series towers, standing waves near the wavelength of the cabinet dimensions will be damped and less likely to interfere with the primary signal produced by the bass drivers.

Another inherent advantage of BH5 is that it is based on an open-cell foam, so there is a negligible impact on the internal air volume that is critical in the proper tuning of these cabinets. Make sure however that your installation of the product is kept clear of the ports, as not to occlude air flow. See this link for a detailed description of Black Hole 5: http://www.gr-research.com/components/blackhole_5.htm .

A similar but slightly less costly (and effective) product is available from Parts Express: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-535 . But as far as I am concerned its in-for-a-dime in-for-a-dollar, and I think the BH5 product would be worth the price differential. If you are going to go to the trouble of upgrading the damping of your speakers, IMHO this is definitely the product to use.

Another effective product that is commonly used in car audio to dampen resonant panels, and by diy sub builders is this product from Cascade Audio: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=268-256 . This might be used to dampen any resonance that might exist in the composite plastic front face, or in the horn itself. I notice that literature on the current Reference line makes a point of talking about increased ribbing, so this suggests to me resonance in some models past might have been a problem. The VB-1x is also used to dampen the inside of subwoofer enclosures. Cascade notes that MDF, which most sub enclosures are made of, is actually slightly porous. Under the pressure that some subs can exert in a sealed application, there can be as much as 3 db of loss (according to Cascade measurements). VB-1x dampens the panel, but also seals the MDF. By the way, Cascade makes some excellent acoustic control products for use in HT applications.

The reality of manufacturing costs dictates that cost-benefit ratios must be carefully examined, and often premium parts in crossovers, and materials such as these will not be used. The typical buyer will not be able to discern the difference, or are simply not willing to pay a premium for a small difference. Especially if the product is labor intensive (such as the VB1) or if a material (such as BH5) is marginally more effective than a more commonly available-and much less expensive-product.

Frankly, I think it is a tribute to Klipsch that their product designers elected to use the acoustic foam that is in the Reference line, instead of the far cheaper and more prevalent polyfill. But I betcha somebody had to fight for it.

So this will boil down to your own cost benefit analysis. Will the benefits of these products be discernable enough, and worth the extra cost to you. I would suggest that someone who is willing to pay for a DeanG modded crossover would be able to appreciate the difference, and it would be worth the cost. But most folks would get more enjoyment for the dollar by investing in media instead.

Most folks wouldn't notice the difference. But then most folks don't listen to Klipsch. And most folks don't hang out on this forum.

[colterphoto1]

the slab of foam is in there to minimize internal standing waves, not to dampen cabinet resonances, they are two separate items. Nearly all boxes will 'thunk' if you rap on them, what does it sound like out front?

[PhilMays]

I had my speakers apart when I took out the x-overs to have DeanG upgrade them. I asked the same question and the general forum conclusion was that they did not need damping material.

We all "tweak" our stuff needlessly from time-to-time. My question would be....would it hurt anything to oplace damping material in the cabinets. If not then I have spent alot of money in the past on things that do not matter. (latest is an audiosource equalizer).

Phil

[Deang]

The RF-7 has two windowpane type braces. Don't add any material, it will screw up the port tuning.

[Jay481985]

the slab of foam is in there to minimize internal standing waves, not to dampen cabinet resonances, they are two separate items. Nearly all boxes will 'thunk' if you rap on them, what does it sound like out front?

standing waves usually cause alot of cabinet resonance.

And with that the Wilson Audio uses a material more akin to Bullet proof glass they call wilson x material..... And it also costs about the price of a house.

[rockbobmel]

The RF-7 has two windowpane type braces. Don't add any material, it will screw up the port tuning.

OK, that was what I was asking about. Although, I did not see any bracing that I remember, or at least across the mid sides fo the cab. Are you talking about inside corner (along the inside 90o ?)

[Deang]

Looks like this (more or less).

[rockbobmel]

Thanks Dean.[]

[Raider]

The speaker which I modded with BH5 was small, only about .15 cubic feet. The BH5 apparently took up about 25 perecent of the internal volume. However the material is based on an open cell foam, so there is a negligible effect on internal volume (much like polyfill) and I found that it did not change the port tuning even in such a small speaker. It did remove some noticable resonances as compared A/B to an un modded speaker. The product is unique in that it helps damp both panel resonances, and standing waves.

I notice that even with two window pane braces, there are still areas not braced that are as long or longer than some bookshelf speakers. Some better quality bookshelf speakers of this size will often have a window pane brace, sometimes more, or may have a longitudinal braces parallel to the front and rear sides. So there may be potential for improvement in the Klipsch towers. However, I am confident though that FEA was likely used by Klipsch engineers to determine the size and spacing of the braces they used, and that this is probably near optimal without making the enclosures too heavy or large. So BH5 may or may not be beneficial for dealing with panel resonance in this case. I would think that a greater potential for improvement might be in dealing with standing waves within the enclosure. With as large a cone area as the towers have, there may well be and adverse effect by energy reflected back through the cones. This can muddy the midrange in much the same way as lack of acoustic treatment can muddle imaging and soundstage within a room.

As with room treatment though, enclosure treatments generally are best when addressing specific problem areas that have been identified. So unless you can identify a specific problem in the sound of your speakers, it will be less likely that there will be a positive cost/benefit outcome. If you like what you hear, money might be better spent on other things, like music. :0)