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Elbert 21st October 2011 07:49 PM

Completed build, for inspiration..
9 Attachment(s)
Finally, after many months of protracted building and finishing..

Anyway, now Im' finished, and I thought I'd give something back to the forum in the form of som images and descriptions, hopefully to inspire others! :)

I decided I wanted a system that could cover all 10 octaves, and decided to go with dual subwoofer/ two way "satelites" actively driven. Posted some other threads on the amp and x-over design...

I decided to go for the Dayton RS39HF 15" woofers:

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 Ohm 295-468

They are in my opinion very good value for money and had a very low Fs, meaning it should be possible to go deep even with a closed box.

I must say that the build quality of these woofers were in deed excellent.

I chose closed boxes as this would give better phase response, plus it would be simple to simulate and predict.

A volume of around 160L gave a simulation of a slightly highish Q, but with the etensive stuffing I employed, my qualified quess is that I ended op fairly close to 0,7 anyway. Simulations allso showed that variations in response were quite modest ovver a relatively wide range of volumes about the calculated ideal. So in other words, not a very critical design.

I decided to go for a wide and low profile, making the enclosures less dominant in the living room, more like furniture than big loudspeaker boxes. The dimensions should make it easy to "blend" them in as a natural horizontal extension of a low stereo/ TV console.

I decided to build them from 22mm MDF with a heavy bracing matrix inside.

I allso decided to place them on a foot made from a 22mm MDF panel slightly smaller than the bottom og the boxes. Yhis effectively hides any missalignments and unevenness that would otherwise become evident if flush. Between the foot and the box, I sandwiched a sheet of 12mm thick "Armaflex" a mushy and elastic sort of cloced cell foam used for HVAC insulation. this was allso slightly smaller than the foot for the same reasons described above.
In addition to being an aesthetic design feature, the sandwiched foam may allso act to decouple any vibrations from the boxes. This is of course theoretical as I have no means to simulate or measure this.

For finish, I went with Teak veneer.
I thought long and hard about how I would finish the veneer.
Laquer was out, I feel it often comes out as "something on top of the wood. Allso geting a gloss laquer finish to look good on such large surfaces is extremely difficult. A matt finish would of course elliminate the problem of imperfections being revealed by reflective highlights, but that is just to "dull".

I decided i wanted a polished wood apearance, something that would give a nice natural near-gloss shine and bring out the lustre of the wood.

I went for oil sanding followed by a wax-polish.

After ironing the veneer on and trimming it, I manually sanded the veneer down to a smooth 100 grit finish.

I then started oil- sanding with two rounds of 240, two rounds of 340, and then finally one round of 400.
This left me with a silj\ky smooth finish with the pores and grain of the wood very nicely filled in.

I used something called Owatrol "edel olje", or "Noble Oil" as it would translated directly, which is intended for hardwood/ exotic wood. EDEL OLJE - H°yglans ocerflate til alle typer av treverk

Probably quite simmilar to various teak oils etc...

The oil-sanding is not as messy as you would probably expect, just put some covering paper on the floor and off you go.

Thebonus with oil sanding, is that you can do it indoors in your living room without creating a sanding dust-disaster. This is a good thing if you, like me, don't have a proper workshop and live under a climate which does not allways lend it self well to extended outdoor activities..

For polishing I used "black bison wax" from Liberon
Wax finishes : Black Bison Paste Wax -

Initially, I considered bees wax, but the liberon wax contained Carnauba wax, something I anticipated would take me closer to the natural shine and luster I wanted. A good choice it turned out.

The front of the boxes was finished with the same foam material used for the sandwich foot, something that allowed the woofers to be "countersunk and gave a very nice and professional finish.

The sound is awesome. if there is low frequency information in a recording, these subwoofers will reproduce it. Completely confident and without straining, even at considerable SPL. Having said that, I haven't dared to crank things up yet, but impressions so far tells me I have reached the end of the road as far as low frequency reproduction goes.

If I may say so my self, the build and finishing came out very nice, and I dare say I've ended up with something resembling heavy expensive audio equipment rather than some half baked DIY projects.

Now for the pictures...

firechief 21st October 2011 08:04 PM

Way cool. Agressive and nicely done.

Elbert 21st October 2011 08:08 PM

1 Attachment(s)
Thanks firechief! :)

Not the best pictures though, just some random snapshots I took during the build..

Here's aother one, not so lucky with that flash-shot, but it presents a bit more detail.

Forgot to mention; Used those "punch in nuts" and umbraco bolts you get as a kit from Parts express. Took great care to get the bolt-circle done precicely. This was indispensable in order to facilitate a smooth assembly and good finish!

revboden 21st October 2011 11:48 PM

nice, I love that feeling of effortless sound, when it just blends into the background when it should, then mule kicks you when it "drops"*.

(*pardon the hippyhop speak, but I think that term is pretty good :p)

m R g S r 22nd October 2011 07:25 AM

Finishing job on them looks great! Good job!!

FE3T 29th October 2011 02:31 PM

Looks very good.
But what can you tell me about the foam you used on the front baffle?

chris661 29th October 2011 07:11 PM


Originally Posted by Elbert (
I dare say I've ended up with something resembling heavy expensive audio equipment rather than some half baked DIY projects.

Now for the pictures...

Yep, the half-baked bit would be me :rolleyes:
I'll get something done one day, promise.

Anyway. Those subwoofers look great. I really like the look you've got there. What're you driving them with?


Parasonic 29th October 2011 07:36 PM

Inspiring, definitely
thanks Elbert, they look great


tb46 30th October 2011 03:33 PM

Hi Elbert,

Thanks for sharing, and very well done.

Could you elaborate a little on the type and amount of stuffing used?


adason 30th October 2011 03:38 PM

I like your horizontal approach to subwoofers Elbert, I think it looks classic.

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