[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.
Thats cool!
Is there any benefits from using concrete though?
Posted at 11:32 am on Jan 22nd, 2007 by PsychoRNGD
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.
Posted at 11:56 am on Jan 22nd, 2007 by SporkRocker
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…
Posted at 12:11 pm on Jan 22nd, 2007 by rockrapdude
@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.
Posted at 12:13 pm on Jan 22nd, 2007 by pragma
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.
Posted at 12:29 pm on Jan 22nd, 2007 by akmixdown
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.)
Posted at 12:34 pm on Jan 22nd, 2007 by strider_mt2k
The project is neat, but when will hack-a-day figure out the difference between speakers and speaker enclosures?
now, a speaker cone made of concrete, that would be pretty weird.
Posted at 1:13 pm on Jan 22nd, 2007 by Standard Mischief
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.
Posted at 1:27 pm on Jan 22nd, 2007 by Sheldon
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).
Posted at 2:58 pm on Jan 22nd, 2007 by Nipponese
With feet like those, its a good thing he dosn’t have hardwood floors…
Posted at 4:31 pm on Jan 22nd, 2007 by wolf
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.
Posted at 5:30 pm on Jan 22nd, 2007 by Del
Just because you can make speaker enclosures with concrete, doesn’t mean you should. It doesn’t sound like a good idea to me.
Posted at 6:47 pm on Jan 22nd, 2007 by Dave
Is it just me, or does “Der Subvoofer” look “Der Painful” and “Der Hole in My Fritschken Floor”?
Just a thought, just a thought.
Posted at 7:12 pm on Jan 22nd, 2007 by StickyWidget
I think the spikes are to prevent the sub from reverberating/vibrating through the floor.
Posted at 8:44 pm on Jan 22nd, 2007 by bjs
So did they just melt the wax out?
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.
Posted at 6:40 am on Jan 23rd, 2007 by Chuck_Notorious
all diy projects require spikes! ;)
Posted at 7:06 am on Jan 23rd, 2007 by MRE
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.
Posted at 7:49 am on Jan 23rd, 2007 by creekree
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.
Posted at 8:43 am on Jan 23rd, 2007 by Undefinition
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.
Posted at 12:31 am on Jan 24th, 2007 by Sammy Taters
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!
Posted at 3:08 pm on Jan 25th, 2007 by dan
for anyone who is interested in the writing on the site here is a google translation link
Posted at 9:39 am on Jan 29th, 2007 by weirdcrap
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?
Posted at 6:47 am on Feb 2nd, 2007 by thomas
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.
Posted at 10:37 pm on Mar 9th, 2007 by JoJO
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.
Posted at 5:13 pm on Mar 13th, 2007 by rich
Very interesting idea. You could probably cast the concrete speakers in different shapes than the usual rectangle.
Posted at 7:08 pm on Feb 17th, 2009 by wholesale merchandise
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Heavy!
Posted at 11:27 am on Jan 22nd, 2007 by ed3