Glass Brick Enclosures

[blupro]

Heya,

I'm new to the world of DIY, and have been wondering about building a set of speakers using cinder block shaped glass bricks as enclosures. The bricks are tinted - dark enough that I could put stuffing/wirings/crossovers in and they wouldnt be seen, but I have never heard of anyone using a glass block as an enclosure...

Is there any reason I shouldn't try this? I'm new to DIY but dont want to put together something that sounds horrible.

I've done a bit of reading on this, and it seems low frequencies would be better for glass enclosures, but I'm hoping I can get some decent high frequency sound as well. If anyone has any experience or ideas on something like this, I'd be keen to hear your thoughts.

Hope everyone's having fun...
Blu

 

[phase_accurate]

Not glass-blocks but glass boxes nonetheless:

http://www.waterfallaudio.com/indexhtm.html

Regards

Charles

 

[richie00boy]

Seems a nice idea. How are the bricks bonded together?

 

[blupro]

Charles - Thanks for the link. I'd seen those, so it gives me hope that glass isnt a no-no.

Richie - they're shaped like this: http://en.wikipedia.org/wiki/Cinder_block. I was thinking a woofer in one opening, and a tweeter in the other.....or two woofers in the holes and a tweeter up top.

 

[richie00boy]

Link no good.

 

[Willitwork]

Is there any reason I shouldn't try this?

None that I know of but since glass blocks will have a different acoustic signature than say MDF, damping and crossover design will have to be adjusted accordingly. What I'm saying is that you probably wouldn't get optimal results by simply using a crossover designed for the same drivers in an identical box made of a different material.

 

[sploo]

blupro,

I would think that a reasonably thick walled glass block would have far fewer vibration issues than an MDF panel, so that would be a positive.

You can of course break glass with sound (http://www.physics.ucla.edu/demoweb...fects_of_sound/breaking_glass_with_sound.html) but I don't think that'd be an issue for a brick (unless you're planning on going really loud).

What would you use for the front and rear panels?

Link no good.

Remove the full stop from the end of the URL (the 'auto URL' code that turns http... into a link often swallows up the full stop at the end of a sentence, and leads to dead links. Affects many forums).

 

[Willitwork]

You can of course break glass with sound (http://www.physics.ucla.edu/demoweb...fects_of_sound/breaking_glass_with_sound.html) but I don't think that'd be an issue for a brick (unless you're planning on going really loud).

I think you'd need a sledgehammer to break one of those blocks or perhaps 40 F-18's breaking the sound barrier at once over your home, they are surprisingly sturdy, and heavy!

 

[blupro]

Charles - sorry about that. The period at the end of the link throws it off. http://en.wikipedia.org/wiki/Cinder_block

Will - thanks for the heads up. More for me to read up on....but thankful that I'm aware of it.

 

[blupro]

Sploo: I'm thinking along the lines of MDF. I'll figure out some way of getting an airtight seal. I'm anticipating I might be able to get a tight base, but have it in my head that it wont go low because of the small enclosure. I haven't even gotten to the point of picking drivers mind you; I've been doing a bunch of reading overall, but thought to make sure glass was ok to use before starting to pick out drivers.

Speaking of that...any ideas what I should be looking for in drivers for use in a thick, fairly solid, non-hollow material? I'll be using a t-amp with this - had originally considered high sensitive drivers in an open baffle, but the baffle size/look wont work for my apartment. I'm now thinking more tweeter/woofer combo.

 

[AMV8]

blupro

Sounds a fantastic idea.

I have used concrete and corian in the past and have found that few changes to the crossover were required. In fact I found that more rigid enclosures seem to work well with linear speakers amd minimum crossovers. Rigid enclosures seem to particularly help with midrange.

How do you make the speaker hole and how do you connect the speaker?

Please post pictures when you can.

Don

 

[Zarathu]

Sploo:
Speaking of that...any ideas what I should be looking for in drivers for use in a thick, fairly solid, non-hollow material?

Have you considered sonotubes?

They are light, have interesting characteristics in closed designs regarding harmonics, and as the pressure inside the tube increases, the stability of the tube increases rather than decreases. Additionally they don't hold energy to be re-broadcast back into the speaker. In sealed applications, you can use optimum densities of fiberglass to virtually eliminate the back wave by attenuation.

They are used in midranges and in even very large woofers.

And they can have a look which is quite different from the boxy normal look.

Zarathu

 

[Teh]

If you're wondering about glass go here.

http://www.perfect8.com/

This is a wonderful example of how far a design can be pressed. Imagine an OB design without any vibration? I haven't heard them but I can already see how much I'd enjoy them. Just a very superb design.

Look closely at the Subwoofer. Also notice that the panel takes off from roughly 80Hz.

I think this design has some very real potential for us mortals. Very real! How? well, instead of glass we can all use carbon composite reinforsement can't we? That is still as stiff, and non-reverberant, as it gets. Isn't it? They (most Commercial offerings) don't want all the processes. They want to glue it together and be done, don't they?

All else can be built in a similar fashion, regardless of the component choices! Imagine with active crossovers and Tri-amplification? All of these commercial designs are intended to be run from someone elses individual channel amp (one channel per speaker). Already they're at a distinct disadvantage just to meet the "masses".

Good luck

 

[rdf]

From my experience building a small cabinet of 1/4" welded steel, I suspect your primary hurdle will be damping glass's internal resonances. It was the steel experience that brought home why they use the material for bells.

 

[sploo]

Sploo: I'm thinking along the lines of MDF. I'll figure out some way of getting an airtight seal...

...Speaking of that...any ideas what I should be looking for in drivers for use in a thick, fairly solid, non-hollow material?...

As long at the brick surface isn't too irregular, you could use use a foam gasket - like what you use when you bolt a driver to a baffle.

Not sure how this fits in with your plans, but you could make a front (baffle) and rear plate, with threaded rod and nuts pulling them towards one another. With a gasket on the inside face of each sheet, and the brick in the middle, you should get a good seal, and that way you wouldn't be trying to glue MDF to glass.

I couldn't recommend drivers, but John Krutke's site has loads of great info from his driver tests (http://www.zaphaudio.com/).

...Rigid enclosures seem to particularly help with midrange...

I've read quite a bit on de-coupling drivers from the cabinet baffle in an attempt to reduce the sound produced by the cabinet vibrating. I think it generally affects the midrange the most, so it's logical that a very rigid enclosure would help.

 

[blupro]

Thanks everyone for the feedback and thought.

blupro

How do you make the speaker hole and how do you connect the speaker?

Please post pictures when you can.

Don

Sploo captured my idea fairly well below ...

In terms of pics - the idea is in it's infancy, so it'll will be a bit. This is my first project....I get a bit nervous thinking about tinkering with crossovers, but it will be fun and hopefully worthwhile.

you could make a front (baffle) and rear plate, with threaded rod and nuts pulling them towards one another. With a gasket on the inside face of each sheet, and the brick in the middle, you should get a good seal, and that way you wouldn't be trying to glue MDF to glass.

I've read quite a bit on de-coupling drivers from the cabinet baffle in an attempt to reduce the sound produced by the cabinet vibrating. I think it generally affects the midrange the most, so it's logical that a very rigid enclosure would help.

Sploo - I feel dumb asking, but decoupling? That that simply mean not putting both drivers on one board? That term has yet to enter my DIY lexicon, but I get the feeling I should be happy you mentioned it....

Seriously - thanks for everything so far people.

 

[Willitwork]

I feel dumb asking, but decoupling? That that simply mean not putting both drivers on one board? That term has yet to enter my DIY lexicon, but I get the feeling I should be happy you mentioned it....

In this case decoupling means limiting the transfer of vibrations between the driver and the cabinet baffle it's mounted on. There are a few ways to achieve this, from your basic foam gasket (even though it's not the gasket's main purpose) to special rubber mounts that sophisticated people call "grommets" -for some reason to me that sounds like a dog's name- to more elaborate methods such as bolting together two drivers mounted back-to-back on separate baffles, such as in dipoles and so-called "isobarik" designs, the theory being that each driver's vibrations will help cancel the other's. Decoupling has two perceived main benefits: lessen cabinet vibrations that colour the sound, and achieve greater efficiency by transferring more energy to the air instead of the cabinet.

 

[neutron7]

bluepro where can non contractor buy glass cinder blocks in canada?

 

[blupro]

Will: I have to agree - Grommet does sound a bit like a dog....and thanks for explaining the rest of the decoupling concept.

Looking at the driver reviews on Zaph, I'm surprised that some of the drivers seem quite reasonably priced. In terms of matching tweeters and woofers, is it pretty much wise to keep it within the same brand? I know the speakers' frequency ranges are important in terms of crossovers; but if the frequency ranges work, is it advised to stay within the same brand with tweeters and woofers?

Neutron: cant help you in locating the bricks. I have friends who are moving who scored some years ago and have been using them in a bookcase. They asked if I wanted them, and that's when I thought about making them into loudspeakers.

 

[sploo]

...Looking at the driver reviews on Zaph, I'm surprised that some of the drivers seem quite reasonably priced. In terms of matching tweeters and woofers, is it pretty much wise to keep it within the same brand?...

If you look at Krutke's site, he makes speakers using all sorts of drivers (pairing from different brands), so I guess it's 'just' a case of getting a good match.

Linkwitz Lab (http://www.linkwitzlab.com/) has some info on decoupling - he uses a rear mount for one of the drivers in his open baffle Orion design. He also has some drawings of clamps more suited to closed boxes, and there's a link to a paper on the subject somewhere (his links page I think).

BTW Dunno about Canada, but those nice US driver prices on John's site are all about half what we pay here in the UK.