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DIY Cinder Block Speaker

Cram

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Aug 30, 2021
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Ok so I saw these and I thought “hell I can do that”. So I’ve done a little bit of research and could use a little bit of help
I’m looking to get this cinder block as, based on my math skills, it has ~1100 cubic inch volume which I think should be large enough for 4-5 inch drivers. I’m super new to all this and I’m looking for a kit that would work for this that has the drivers, crossovers etc. I have some basic woodworking skills so can make the wood front and back.
Thoughts? Am I in over my head?
 

JWAmerica

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Looks good. Give some thought to damping materials. Concrete may not resonate much but it does reflect sound. At the very least you'll want some polyfill. A layer of mass loaded vinyl or other damping sheet material is also worth consideration as long as it's relatively thin so you don't lose enclosure volume.

I don't think you really need a kit if you can cut the wood. The drivers will likely be cheap and the crossover simplistic. Take a look at Parts Express with some very basic knowledge and you'll be able to put together a two-way with an off the shelf crossover that probably sounds better than the kit. I like the cinder block as an enclosure. Don't need to worry about bracing.
 

egellings

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You have to bust out the center divider in the block, right?
 

egellings

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I'm surprised that a half a cinder block is enough box volume for the driver.
 

egellings

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A half of cinder block seems like an awfully small box volume for the woofer. Tweeter needs no box volume at all.
 

tomchr

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The woofer is in the lower volume and the port is in the upper volume, with no apparent path from one to the other.
I had the exact same question.

I'd also bring the wires out the back rather than out through the side.

Tom
 

alex-z

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A cinder block might have enough volume for a 4-5" woofer, but then you will lack bass output, especially in a sealed design.

I would go with something like the Classix II MT kit if you want budget bookshelf speakers.
 

amirm

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I love the way it looks like a little robot.

HphuChSTT49VQSxaxSCBdM-1024-80.jpg.webp
 

Beershaun

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Damn thing sounds like a brick.
Likely a good match for...Rock Music..."She's a...brick...house."
Oh man I could go for days...:p
 

headshake

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Apr 20, 2019
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Ok so I saw these and I thought “hell I can do that”. So I’ve done a little bit of research and could use a little bit of help
I’m looking to get this cinder block as, based on my math skills, it has ~1100 cubic inch volume which I think should be large enough for 4-5 inch drivers. I’m super new to all this and I’m looking for a kit that would work for this that has the drivers, crossovers etc. I have some basic woodworking skills so can make the wood front and back.
Thoughts? Am I in over my head?
This kit is about the same size:
https://sbacoustics.com/product/bromo/

There is another version too that is probably the same size. The website has more. The parts should be easy to find.

I am sure there are more kits. I've heard that tweeter and it sounded nice.

Best of luck!
 

DVDdoug

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May 27, 2021
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IIuc having two chambers helps isolate the speakers?
Almost all tweeters are sealed in the back so that's not normally an issue.

they do make cinder blocks without the center so I could go with that.
That should be better. Or you could make a "spacer" (like a gasket around the outside) about the same thickness as the front & back, allowing a gap in the center for the front and/or back.
 
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