Concrete Speaker Project: Part 1

[dbane883]

Aside from watches, my other hobbies include working with various concrete mixtures to make countertops, furniture, etc as well as hifi audio.  So last summer I embarked on a project that combined both of these interests and built prototype speakers with enclosures made entirely out of concrete.  The problem with many traditional speaker cabinets made out of wood/mdf is "resonance".  Could be good if controlled,, could be terrible if its not. Eliminating resonance is one way to get a purer sound from the drivers.   

 

I decided on a closed cabinet design using an economical tweeter/driver set from Dayton Audio.  The excercise was more to see if a completely closed design could be built.  The crossovers would have to fit through the woofer hole.   Here is the final product:

 

 

I started by drafting the cabinet form on paper, and cut out pieces of acrylic/plywood for the drivers:

 

The form itself was made out of melamine, which is slick enough that once the concrete is set, it's easily removed:

 

Because the final product has to be hollow, i created the hollow forms using syrofoam:

 

I also embedded aluminum rods beside the driver knockouts.  These will later be used as to secure the screws for the drivers themselves:

 

Driver knockouts in place:

 

Followed by the styrofoam (the rods will create the channel for the binding posts):

 

The pour was a near disaster.  Apparently securing the styrofoam with two sided tape was not ideal, since styrofoam floats!!.. I had to litterally push it down while i as pouring the concrete until it was semi-set:

 

Once the forms are released, it's not a pretty sight:

 

Slowly chipping away at the styrofoam interior:

 

Test fitting the drivers..perfect:

 

Drilled the screw holes into the aforementioned aluminum rods:

http://i123.photobucket.com/albums/o309/darthbane883/Concrete%20Speakers/IMG_0157_zpsbe94834b.jpg

 

Now the grinding/polishing:

 

After several hours of wet polishing using diamond resin pads:

 

Tapping and final assembly:

 

Prototypes complete:

 

Despite a few hiccups along the way, overall, I think the process was a success.  The speakers sound incredible and on par with speakers that cost $3k-5k easily.  

 

While the process might seem a bit crude, you gotta remember, I didn't have a guide to work with.  I've never really seen this done before and there is definitely room for improvement. 

 

But this was just a prototype which I'm currently using in my home office.

 

My project this summer will be to build the ultimate home monitors using some high end Danish Scan Speak tweeters/woofers using custom-made cross overs.  I think i will be using a ported design this time.  Stay tuned.

 

 

 

 

[cc33]

Wow

[Dlf]

What a great finish, I'm a big fan of polished concrete.

Awesome work!!!

[asciwhite]

Magnificent!

 

 

I love sound! Listening to good music should be like a cup of rich chocolate for your ears and your soul!

 

Looking good buddy!

[Original Scope]

Wow,just wow.

[TwysT]

Wow, this is an amazing project, so unique. Think they turned out stunning!

[droptopman]

Wholly smokes that is one cool project.  I love the way they polished out.  Looks awesome.  You continue to amaze.  You are one talented guy.

[mjmj]

They look great. So, what don't you so?

[danielv2000]

[censored], that is nice!

[panerai153]

Those look great!! You are truly a multi talented fellow. Is this conventional concrete? Just wondering if it was some sort of lightweight material. Also did you add anything to the mixture to prevent cracking. Some people are using fiberglass in the concrete to prevent cracking, just wondering if you used something like that.

[dbane883]

It's 6000lb concrete. For 1" thickness for these dimensions, its more than plenty with the aggregate I used. Polyfibres are useful if the spans are greater than say 18" at 1" thick. The enclosures are not load bearing anyways like a countertop might be

[508-Fanatic]

Any issues with standing waves in the concrete form? They look really amazing. 

 

I sold high-end audio for years at a boutique shop... McIntosh, M&K, B&W, Linn, Meridian etc... I think a lot of it's nonsense price-tag wise except for stuff that's bench-made like McIntosh and lasts 50+ years. I grew up with Mc gear, and it still works to this day and sounds great. The problem I have with high-end audio is that people are always (not you, just folks in general) seem to be trying to re-invent the wheel and then charge *huge* money for speakers and gear that isn't any better than product costing 1/5th of it's price.

 

Case in point in the watch world the new Grubel Forsey $300k tourbillon with a bump on the back of it... an ugly watch and probably uncomfortable. But it's haute-horologie and despite being utter nonsense they're all spoken for. Same thing happens in high-end audio with $20,000 speaker cables and other bullsh*t.

[highoeyazmuhudee]

very cool!! should make a side by side audio comparison with mdf cabinets. i think this is how energy audio started, then sold out to china and now makes garbage.

[Nightwatch]

Fascinating project and top-of-the-line looking end result. The polishing and embedding of the Nautilus give the final touches. This was interesting.

[Paulza]

That's amazing. How much do they weigh?

[dbane883]

Any issues with standing waves in the concrete form? They look really amazing.

I sold high-end audio for years at a boutique shop... McIntosh, M&K, B&W, Linn, Meridian etc... I think a lot of it's nonsense price-tag wise except for stuff that's bench-made like McIntosh and lasts 50+ years. I grew up with Mc gear, and it still works to this day and sounds great. The problem I have with high-end audio is that people are always (not you, just folks in general) seem to be trying to re-invent the wheel and then charge *huge* money for speakers ....

No issues at all. I think the imperfection of a raw concrete form has imperfections of symmetry and I didn't find any issues. I will intentionally use more of an asymmetric design on my next project.

Like many "luxury" watch brands, many speaker manufacturers do not make their own tweeters and woofers. The drivers I'll be using next are the exact same ones used in $15k Revels. Crossover and enclosure designs are the differentiating factor.

As for weight, they are about 40lbs each

[tomhorn]

Any issues with standing waves in the concrete form? They look really amazing. 

 

I sold high-end audio for years at a boutique shop... McIntosh, M&K, B&W, Linn, Meridian etc... I think a lot of it's nonsense price-tag wise except for stuff that's bench-made like McIntosh and lasts 50+ years. I grew up with Mc gear, and it still works to this day and sounds great. The problem I have with high-end audio is that people are always (not you, just folks in general) seem to be trying to re-invent the wheel and then charge *huge* money for speakers and gear that isn't any better than product costing 1/5th of it's price.

 

Case in point in the watch world the new Grubel Forsey $300k tourbillon with a bump on the back of it... an ugly watch and probably uncomfortable. But it's haute-horologie and despite being utter nonsense they're all spoken for. Same thing happens in high-end audio with $20,000 speaker cables and other bullsh*t.

 

I sold high end gear myself for several years. I loved selling to people who thought things were better because they cost more. Plenty of "audiophiles" fell into that group.

 

Funniest story I had from back in the day was going to meet my (then) girlfriend's step father who had about $20k wrapped up in a Linn turntable, Accoustat speakers, and Levinson Amp/Preamp. He asked me what I thought of the sound while he was playing Michael Jackson's Thriller. Told him his low end was rolling off hard below 100hz. He told me I was nuts. Next time I stopped by there was a Velodyne sub sitting in the corner ...

[Nanuq]

Spectacular!! I used to make corner horns using Klipsch plans and 1" birch. I bet your ideas would build the ultimate setup.

[martijnp]

Impressive project! Very unique look, i really do like it

[astonjenks]

Great work and a true labour of love.

AJ

[rrari1]

What aggregate did you use?  What Speaker set did you buy from Dayton?  

 

I love the finish.  Amazing work!!  Keep us up to date on any other projects.

[dbane883]

I used a mixture of sand, pea gravel, pebbles from the beach by my house, crushed coloured glass.   I think the speaker kit I used were the Dayton Audio RS621.   Cheap but a great kit for a prototype project like this cause you just never know how it will turn out.

 

This summer's project will be using all hand-picked parts, even for the crossover components.   

[xpletiv]

Did you happen to use Cardas wiring with that?

It's been said that even though the drivers may look the same, how they are made makes them different from those that are right off the shelf. Sounds familiar.

Some drivers for some brands have different specs for the VCs so they may look the same, but different types of wire may be used along with a different resistance. Blah, blah, blah.

Cool project, but I wouldn't want to move them.

[dbane883]

ha..  not cardas, but I did you some decent Audioquest cable for the internal wiring.. Nothing crazy

[asciwhite]

-------

 

Well there are quality components and there are "too much money components" I always opt for the best quality because I don`t have too much money

 

Stuff like dbane883 have done here is right on the money for your own hi-fi experience

 

But buying shielded power cables and stuff like that for $1200 a pop is wasted money in my book. And much other stuff like crazy expensive HDMI cables and the like. Then you are just paying because it is a status thing.