Concrete 2-way monitor speakers, a good idea??

[Antares]

Been wanting to build my own pair of monitoring speakers for my tiny 3m L by 3.2m W by 2.8m H bedroom for a while now, and researched that concrete would be a great material for use in a cabinet due to price and acoustic properties as I would be able to get them closer to the rear wall and reduce transmission to the stands.

The drivers I plan on using are

• Tang Band W4-1720 4" Underhung Midbass Driver rated at 30W Rms - 60W max - 4 ohms.
• Fountek Neo X 1.0 Ribbon Tweeter Black rated at 20W Rms - 38W max - 8 ohms.

With a x/o between 1.5kHz to 3kHz, active via MiniDSP and powered by a 4x100W wondom amp board. with an estimate around $550 including all parts.

Here's a basic sketch of the design, Ideally the corners would be rounded and with an angled back to reduce direct reflections to the woofer. (I'm not 100 percent sure about the angled back idea tho...) and I plan on adding a subwoofer system in the future to go with the monitors.

Sealed design:


Ported design.



At this price range including all the parts, would this be a good system to build? or should I get a $500 pair branded monitor speaker system??

I would use the system for casual listening as well as music production and basic mixing and would love to have ribbon tweeters. but it this idea worth the effort???

---

List of all the parts planned for the build, no cabinet included.

• 2 x Fountek Neo X 1.0 Ribbon Tweeter Black --------------------------------------------------------------------------------------------($78.90 each x 2 = $157.80 )
• 2 x Tang Band W4-1720 4" Underhung Midbass Driver -------------------------------------------------------------------------------($55.79 each x 2= $111.96)
• 1 x MiniDSP 2x4 Kit Digital Signal Processor Assembled Board ------------------------------------------------------------------($80.00)
• 1 x WONDOM AA-AB33182 4x100W at 4 Ohm Class D Digital Audio Amplifier Board STA508 (TK2050) ------------($55.98)
• 1 x Mean Well MW NES-350-24 24 VDC 14.6A 350W Regulated Switching Power Supply --------------------------------($35.97)
• 1 x Dayton Audio EMM-6 Electret Measurement Microphone ----------------------------------------------------------------------($45)

I will use binding posts for each driver, so 2 pairs per speaker.

• 4 x Dayton Audio BPA-38G HD Binding Post Pair Gold------------------------------------------------------------------------------(4 x $5.00 each x 4 $20.00)
• 4 x Dayton Audio BPA-38G HD Binding Post Pair Satin Nickel--------------------------------------------------------------------(4 x $5.00 each x 4 $20.00)
• 1 x RCA AH1650SR 16 AWG Speaker Wire Spool 50 ft.------------------------------------------------------------------------------($8.96)
• 1 x Parts Express Chassis Mount RCA Jack Pair -------------------------------------------------------------------------------------($6.99)
• 2 x Banana Speaker Plug 2 Pair--------------------------------------------------------------------------------------------------------------(2 x $9.95 each = ) Opcional.

• Total: -------------------------------------------------------------------------------------------------------------------------------------------------$561.76
• Total without banana plugs.------------------------------------------------------------------------------------------------------------------$542.28

This project I posted on the tech talk before coming to the final list of parts and price, you con look at that post under the name: Help with a 2-way monitoring system in a concrete box.

[billfitzmaurice]

Wrong forum. That said I'd never build a cab with concrete.

[Antares]

Sorry, will move to the project gallery.

[Sydney]

Antares: Despite naysayers - I have seen Concrete used in the past, Have to looked at examples on-line?

[billfitzmaurice]

Sorry, will move to the project gallery.

The project gallery is for completed projects, not contemplated projects.

[Antares]

I've read that in the 70's there were several brands building concrete speakers, I got the idea out of several places where I read that concrete would be a superb material for a speaker build, due to it being really stiff and reducing transmission of sound out of the box as well as providing almost no coloration to the sound. good absorption materials should line the interior tho.



Here's a really nice design I found currently being produced by Master & Dynamic.

[Sydney]

http://www.homecrux.com/25-concrete-...ngevity/78665/
https://www.concrete-audio.com/en/
Concrete Cloth looks promising

[Antares]

As soon as I have the build I'll post them, thanks billfitzmaurice tho.

I think I might give a try to the concrete idea anyways, around 2cm or 3/4" thick, lined with rubber perhaps and some polyester fiber for a sealed enclosure and a thick rubber support for the woof to Isolate it from the box.

perhaps a bit thicker if I use styrofoam concrete but would have to test...

[bbnet]

Had heard about these concrete speaker cabs but never seen/listened to them.

Thought that building the cabs out of 3'x5'x1/2"x2 dura roc tile boards might work. Could join pieces with fiber renforced fillets and smooth the finish with thin set.

Might be easier than building complex form?

[billfitzmaurice]

When you can realize a basically inert structure with braced MDF there's no engineering reason for anything more complex, exotic or expensive. There is a marketing reason, which is to appeal to those who think that more complex, exotic or expensive means higher quality.

[Sydney]

...Thought that building the cabs out of 3'x5'x1/2"x2 dura roc tile boards might work. Could join pieces with fiber renforced fillets and smooth the finish with thin set.
Might be easier than building complex form?

I believe I saw an article that used Durock type board decades ago.

One innovation that would open a whole new realm of fabrication is 3D type Additive Fabrication.
Companies like Cybe have a 3D printable mortar material that is a quick-drying cement product, formed within an hour, to freeform or parametric designs that do not need the frames and support structure, complete hydration/ curing process in under 24 hours, and will be completely watertight.
Their ProTo 3DP prints a 7.5-foot-tall object in just about 20 minutes
The same concept could easily be adapted and applied to fabricate "Crete" cabs in any shapes which are not easily done with flat Wood panels.