Concrete cast speakers


[Markus] sent in his 5.1 concrete speaker project. Each speaker is cast from a single piece of concrete. The inner cavity is created using the dear old lost-wax technique. The writeup is in german, but the process is pretty clear.

35 thoughts on “Concrete cast speakers

  1. What would the benefits be? A room-mate that can’t jack your nice speakers. If you live in a dorm as I do. Moving them would be a bitch though.

  2. well the concrete will give a hermeticaly sealed boxes so the bass will be very good.its because the bass box doesn’t leak and the bass will sit where it was placed and not moving around.but i dont know about the speaker boxes…

  3. @psychorngd: I wondered that myself. Then I Googled around and found this site:

    http://www.io.com/~dylan/speakers/

    (also has a few tips on coloring and finish)

    In short, YMMV, but concrete gives a better bass response, with a higher resonant frequency of conventional cabinets. So, generally speaking, dense = good.

  4. A friend of mine did something similar to this about 15 years ago… using concrete drainage pipes. I believe he was going to try his hand at pouring at some point, but I don’t think he actually went ahead and did so.

  5. When I was growing up a friend’s dad had a pair of speakers with concrete backs.
    They were very heavy, but you could hear the difference in the bass response. (I had an interest at a young age.)

  6. The main thing for wanting concrete cast speakers is not less about the hermetically sealed nature as that can be achieved with simpler material and a bit of silicon sealant but the distinct lack of cabinet flex.
    If the cabinet itself (i.e. the box the drivers are in) flexes with the changes in pressure from the driver then the response of the speaker is altered (the cone ‘rebound’ from the pressure is altered as the box absorbs some) which results in mudded sound (the box acts as a speaker itself) and lowered bass response.

  7. I was thinking of doing something like this for a few months. I was thinking of using cinder blocks instead and just mounting the speakers in them. Pretty cool project however.

  8. I have made concrete speakers similar to this about 7-8 years ago when I was still in school. Cabinet flex is not as much of a problem in a box of a smaller size and with good bracing, is not much of a problem at all in traditional enclosures constructed from MDF. The biggest gain in using concrete is in box resonance, which it would be absent. no coloration from the enclosure means you get closer to the sound the recording intended. Also, depending on the concrete you use, it can be made quite light weight (well, not as light as MDF maybe, but close).

  9. Many years ago, probably ’92 or ’93, while reading Car Audio and Electronics (instead of paying attention in algebra class…) I came across a similar thing. The guy had a “normal” sub enclosure in the trunk, built out of 3/4″ MDF, properly tuned, ported, etc… After the box was built, one side at a time (6 pours) he poured like an inch of concrete in the box. Of course the tuning and porting was done taking into account the thickness of the concrete. Ended up with a bigass heavy box holding a couple of 12s, and it seems like he “had to” beef up the rear suspension a bit.

    They said higher density enclosures sound better. Mostly I figure the project was more for bragging rights, since that much energy spent in sound-proofing and vibration-damping in the car would have probably been more effective.

  10. Just because you can make speaker enclosures with concrete, doesn’t mean you should. It doesn’t sound like a good idea to me.

  11. Is it just me, or does “Der Subvoofer” look “Der Painful” and “Der Hole in My Fritschken Floor”?

    Just a thought, just a thought.

  12. That’s what I though when I first saw it…

    It is certainly an interesting idea, but I don’t really see it being all that useful for bookshelf speakers. Maybe for a big sub, but not bookshelf speakers.

  13. Here in Canberra, there used to be somebody who was into making concrete speakers (I guess in the 80s). They would be spheres spun on a potter’s wheel. My dad used to have some but he sold them when I was little (unlucky for me…), a friend of mine has some as well as a classical record shop and I’ve seen one other pair.

    They all sound amazing.

  14. nice!
    although i would have preferred it if they had left the speakers looking like concrete… i mean, its all a matter of taste, but this paintjob is … kinda awful.

  15. The reason you would make concrete speakers is the same reason Medium Density Fiberboard is the material of choice for speakers: very little resonance. In a guitar or violin (or a drum, for that matter) resonance is good. But in a speaker, the only thing resonating should be the driver itself, and the air inside the cabinet. If the walls of the cabinet resonate, you will get unwanted muddiness, or unwanted peaks in the frequency response.

    The spikes in the bottom of the subwoofer are standard issue on audiophile speakers (and most DIY jobs). They are said to “limit floor coupling.” That is, have the least amount of contact with the floor as possible so that the floor doesn’t pick up bass frequencies and resonate with the drivers.

    I personally think the paint job is pretty cool, by the way. Certainly not a color scheme that will please all tastes, though.

  16. So the point of this is to stop sound waves from losing SPLs to your cabinet, and force them outward instead….but what about the driver physically touching the conrete? What material is that.

    I dont think this is going to sound much better unless his drivers are perfect.

  17. It’s a big shame you painted them!! They looked a LOT better with the raw concrete look. Why hide the fact they are concrete – that’s the whole point!

  18. I realize the molds would have been more complex, but he could make the speakers any shape he wanted so he chose to make them look like conventional ones?

  19. If it was me, I would not use wax. Make what you want to dissappear out of styrofoam and then later just pour in a solvent to make the foam melt away. And for the concrete to be lighter use 1/3 pumice.
    I make things in concrete all the time.

  20. I built a sub with dual 15 ” yamaha accordian surround paper cone speakers using 2″ thick concrete poured into all sides of a divided particle board box/w 4″ ports. at first i stuffed the boxes with baffling material,the bass was so low we couldnt hear it,yet it shook the entire house. When we took the baffling out we could actually hear the bass which was incredible. Concrete can also be used as a base to mount your high frequency drivers. Using spiked feet this can reduce unwanted transfer of vibration from the low frequency drivers. Email rjjc1929@yahoo.ca for more info.

  21. The difference between a wood or plexiglass box and a CONCRETE box is this,the much (higher)density of the concrete box among other atributes makes a world of difference! bar none!, when you have a 6db +- gain on a wood box, you might have a 7-8db +- gain on a plexi box, you get 32-36db +- gain difference on a concrete box, absolutely NO comparison!

    When you go into a tunnel(concrete) your car seems to get 10x Louder,or in an underground parking lot(concrete) again your car seems to get much much louder, that is the properties of concrete at work

    THERE IS ABSOLUTELY NO COMPARING (WOOD,FIBERGLASS,OR PLEXIGLASS) TO CONCRETE

    some of the LOUDEST concert halls around the world are made of CONCRETE

  22. Another great advantage is the wax block can be carved and shaped in such a way as to not allow standing waves to develop inside the cast enclosure. i.e with no paralel surfaces & carefully designed ribs inside that diffuse reflected soundwaves. Much like sound-lab walls.
    My next house I want to cast a subwoofer pit right into the concrete floor slab. Like they do with some floor safes.

  23. I never went in a wooden tunnel, neither a wooden parking lot. But I guess my car would get louder in any closed space.

    Is there any results? Does it sound good?

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