Speaker enclosure - filling in the gaps?

[royalcrown]

I currently own a pair of the insignia bookshelf speakers that everyone's been talking about. Glazing over some forums, I had gleaned from pictures of the internals that the MDF used in construction was slotted, and therefore needed some sort of material to reinforce the MDF by filling in the gaps. However, the conventional methods used (either wood putty or "liquid nails") seemed to, being water based, warp the enclosure. Would there be any alternative "filler" material available that wouldn't warp the MDF? I'm assuming the warp-age comes from the MDF absorbing the water in the base of the materials. I'm looking to keep this relatively cheap (under 30 dollars, preferably under 20) seeing as I only spend 50 on this pair, and the speakers are used as a replacement for computer speakers.

 

[zumbo]

Save the money to put towards a new pair of speakers. Why would you want to invest in a product that was a waste of money in the first place?

 

[Droshi]

I'd say a good epoxy is your best bet. They make some powders that you can mix with the epoxy to stiffen up the viscosity. Nice thing about epoxy is that it doesn't shrink and isn't drying based (once the two chemicals are mixed the reaction occurs that cures it, so it can even harden without being exposed to air). Also epoxy cures to a hard rubber type material, so it can actually flex a bit with the material around it. Sounds like it might be what you need...

Most hardware stores have a syringe of the 2-ton epoxy, though the powder to stiffen it will be a bit harder to find.

Hope that helps.

 

[royalcrown]

The epoxy idea sounds neat. How much do you think I'll need? They seem to come in 1 oz syringes, but won't I need like 10 per speaker to fill in the gaps?

 

[Sheep]

Read this.

http://www.gr-research.com/insignia.shtm

Unless you're willing to put some time and effort (and money) into these, it's not worth it to keep using them as a main speaker.

I'm going to agree with Zumbo and suggest a new set.

SheepStar

 

[Rob Babcock]

I think they're good sounding for the price, and as cheap as they are why not try modding them? You'll learn a bit about what makes speakers tick and have the satisfaction of knowing you (hopefully!) made them better.

I second the recommendation of Danny's link. True, his mods substantially increase the cost of the speaker but it will give you some ideas about what you might want to try.

One thing that might be interesting is silicon calking. It wouldn't make them stiffer per se, but it may deaden the enclosure a bit.

 

[j_garcia]

Danny really knows his stuff ; he's easily one of the best x-over designers I've seen.

The problem with those speakers is, after you put time and money into them, you reach a point where you could have just gotten a better speaker like the X-LS to begin with or bought the A/V-1 kit and spent that time and money building enclosures for them.

If you just deaden the cabinet, that alone should go a long way to improving their sound, and for $5, the stuff he recommended should be a cheap mod with real results. Note also that those speakers go on sale for even less than that once in a while.

 

[jaxvon]

I would recommend that if you decide to add damping material to your speakers that you forgo the expensive No-Rez stuff that Danny recommends. Peel 'n Seal is a roofing material that is available at Lowes for about $14 for a 25'x6" roll. Six layers applied to all surfaces inside a speaker in addition to high density fill (6lb-8lb/ft^3 mineral wool) will work wonders for reducing cabinet coloration. Your speakers also have a removable front baffle that would also benefit from Peel 'n Seal application.

The truth is, almost any speaker can benefit from the aforementioned modifications. Virtually any speaker on the market suffers from cabinet resonance coloration, even many expensive speakers.

 

[royalcrown]

I was actually thinking of getting Peel 'n Seal, but I wasn't sure if that would help the fact that the MDF is slotted, since those gaps wouldn't be able to be filled. Silicon caulk might work.

Two things:
1. I have already seen the GR Research mod (minus the crossover) and it seems to be decent, however someone using a similar substance (liquid nails) ended up with a warped cabinet, and hence my search for a non water-based solution. However, I've not counted it out, and if all else fails I'll be picking up a bucket of it and crossing my fingers.

2. About the comments for getting a new speaker: these are not my main speakers. These simply are used to produce sound quality superior to that of my old PC speakers (some logitech 5.1 speakers which really blew). This is used in a very small room and is only really used for listening to music when doing homework. That being said, I'm simply trying to maximise sound quality without going over my budget of around 100 dollars total (30 for a t-amp, because it was the cheapest integrated amp I could find at the time, +50 for the speakrs = 80).
I realize I could benefit from better speakers, however... it would still cost more money. This is also the principal reason for me opting out of the redesigned crossovers - simply too much money for my modest goals.
Now that's taken care of, anyone else have any reccomendations? I might read up on that silicon caulk. If I couple that with the peel n seal I might be good to go. I'm still open to suggestions of course.

Thanks for all your help

 

[j_garcia]

I think silicone will help, but it won't add any rigidity to the enclosure the way something like liquid nails will, and it will smell a lot due to the amount that you will need to use for the whole speaker. The amount you need will probably cost more than the stuff Danny recommended too; a standard tube of caluk is already more than $5 and you will need more than 1 tube I'd imagine.

 

[royalcrown]

I don't think price is a principal concern at this point as much as warping of the enclosure. Do you think shellac spray would seal off the MDF, or would that just damage it further?

 

[WmAx]

I was actually thinking of getting Peel 'n Seal, but I wasn't sure if that would help the fact that the MDF is slotted, since those gaps wouldn't be able to be filled. Silicon caulk might work.

Two things:
1. I have already seen the GR Research mod (minus the crossover) and it seems to be decent, however someone using a similar substance (liquid nails) ended up with a warped cabinet, and hence my search for a non water-based solution. However, I've not counted it out, and if all else fails I'll be picking up a bucket of it and crossing my fingers.

2. About the comments for getting a new speaker: these are not my main speakers. These simply are used to produce sound quality superior to that of my old PC speakers (some logitech 5.1 speakers which really blew). This is used in a very small room and is only really used for listening to music when doing homework. That being said, I'm simply trying to maximise sound quality without going over my budget of around 100 dollars total (30 for a t-amp, because it was the cheapest integrated amp I could find at the time, +50 for the speakrs = 80).
I realize I could benefit from better speakers, however... it would still cost more money. This is also the principal reason for me opting out of the redesigned crossovers - simply too much money for my modest goals.
Now that's taken care of, anyone else have any reccomendations? I might read up on that silicon caulk. If I couple that with the peel n seal I might be good to go. I'm still open to suggestions of course.

Thanks for all your help

I would avoid the No Rez stuff. I am not aware of how it would come close to the effectiveness of the materials I am going to recommend, which will end up being about the same cost: Use at least 5 layers of peel n 'seal. It will take 1 roll per speaker at about $14 per roll from Lowe's. Rip out the worthless acoustic foam and fill the internal volume with 6-8 lb/ft^3 density mineral wool board. I will gladly send you the mineral wool board for actual cost if you PM me. I have used these modifications, and double blind tested the results on this particular speaker to verify effectiveness. It was a substantial improvement by itself. I have also subjected several people to single blind tests regarding this modification vs. an unmodified unit. All subjects commented that the modified speaker lacked the "hollow sound" of the unmodified unit when blind testing. The single blind tests were performed in a real room, and switched using a switch device. The double blind tests were produced by recording music samples in an anechoic chamber and then playing back the samples on monitor headphones using an ABX compare program.

To get the last bit of performance, use the Danni Richie crossover design to improve the driver response. But don't use the excessive cost parts that he recommends. Use the same values, but buy lower cost standard parts.

-Chris

 

[WmAx]

I don't think price is a principal concern at this point as much as warping of the enclosure. Do you think shellac spray would seal off the MDF, or would that just damage it further?

You commented that Liquid Nails warped one. This is not water based. I would speculate that the warping is being caused by the shrinkage of the filler material pulling the cut slots closer together internally. Just a guess.

-Chris

 

[j_garcia]

You commented that Liquid Nails warped one. This is not water based. I would speculate that the warping is being caused by the shrinkage of the filler material pulling the cut slots closer together internally. Just a guess.

That would be my guess too. Liquid nails sort of "shrinks" as it dries, so it probably pulled the cabinet in because it is so weak.

 

[royalcrown]

Wow wmax. That's a pretty elaborate test, so I'll follow your methodology; so you don't think that using a filler material would be necessary? Looks like the peel n seal and upgraded acoustic foam produce good enough results. Although I might do the rock hard putty as well, since it seems to only be around 5 bucks. Thanks for the suggestions.

 

[WmAx]

Wow wmax. That's a pretty elaborate test, so I'll follow your methodology; so you don't think that using a filler material would be necessary? Looks like the peel n seal and upgraded acoustic foam produce good enough results. Although I might do the rock hard putty as well, since it seems to only be around 5 bucks. Thanks for the suggestions.

The filler may help by some additional amount, but this raises the panel resonance frequency, it does not do much to reduce the resonance(except for the pure function of increased mass takes more energy to move). The Peel N' Seal converts a large portion of the resonant energy to thermal form. Ideally, one would do both, if it is *feasible. As for upgraded acoustic foam -- unless you are going to buy an expensive premium grade such as Auralex, I would stay away from foam. At best, it seems that the premium grade foams can equal the functional performance of high density mineral wool board, but at a much higher cost.

-Chris

*Note: The Peel N' Seal needs a relatively even surface to adhere properly, considering the tight space you have to work with in this small speaker. If you use a filler material inside, it will make proper installation of the Peel N' Seal more difficult unless you have a smooth surface. In addition, some materials, such as the water putty, have a questionably stable surface. You would need to paint the water putty after it dried in order to insure a long term suitable surface for the Peel N' Seal.

 

[royalcrown]

Sorry for the confusion; when I wrote acoustic foam I was thinking of the wool board/fiberglass/what have you, it just got loast in translation somewhere along the line.
So I guess I'll bypass the putty filler. It sounds like alot more hassle then it's worth. It's kind of a good thing that the acoustic foam was brought up however; from what I've seen of pictures of its innards, it does seem to be lined with some cheap acoustic foam. My question: Should I leave it in there with the wool board, or take it out and use the wool board as a replacement? I figure in the latter I can use the foam to plug the ports of the speaker. Right now socks are in there; invisible but obviously less than ideal.

 

[j_garcia]

A sock is no less ideal than any other plug - it does the same thing, as long as you don't mind them being there.

 

[royalcrown]

Hm, that's interesting. I have always thought that the socks wouldn't block out as much as something specifically designed to. I guess iwas mistaken there. Then again, I might do the thing above simply because the socks don't make a very tight fit.

 

[ARRAY]

I'd recommend auto-body filler.