There has been a lingering interest in subwoofer for as long as I have
been into home theatre. I never could get me to buy one and I thought building
it myself just wasn't for me. Until there was one article in Hifi-lehti.
It was stated that you can have almost linear response down to 20 Hz in 50 liter vented box with this exiting new 10" XLS- driver from Peerless.
Almost immediately I was completely for it. I ordered two drivers from Ljudia. After 5 weeks of tormenting wait they arrived and The Package was found at my local post-office, not without a bit of a hassle thought.
As you can see, I opted to go for two of these boxes. Well it seemed like a good idea at that time. Seriously, 10" driver can't possible produce the amount of racket I want and drivers were cheap enough. OK I have to admit, bigger is better and two is more than one. Fact is that placement can be even easier with two boxes so on we go...for the real stuff of construction.
Boxes are identical, made of 25 mm thick MDF-board. Inside are triangular reinforcements from the same MDF. Pictures here. I bought boards sawed to measurements and it was next to trivial to stick them together with glue and 5x45mm screws. What we have outside is basically a cube measuring 450 mm a side. Just hope they will be strong enough. To avoid explosions I'm thinking to add some strength by pouring epoxy resin + sand mixture inside on all surfaces but haven't done that yet. Resin would be that polyester-stuff used usually with fiberglass-cloth. That goo would also be great to attach 70 mm vent-tubes, maybe they would stay attached with some good glue.
Well I opted not to start hassling with the resin and just trust the screws, glue and braces. Vent-tubes were glued with Kontaktiliima and 2 screws were also applied for added strength.
What should I pick for outside finish? Maybe self adhesive wood-imitation plastic is easiest and not too bad looking either. Black of course, you know that black speakers sound best :)
Yes! my little subwoofer-project is now finished and I have two black boxes more to disrupt things in our happy home :) ...and there's enough for neighbours too ;)
At the moment I'm driving these boxes with my trusty old NAD AV-316. Too bad this means that I can't anymore boast with DD EX...happened to drive rear speakers (left, righ and center) with that NAD. Also decoding of 3 channel surround matrix from stereo rear signal was done with it. Well one can't have everything and subwoofers anyway sound better than extra rear channel. So it's _only_ DD 5.1.
And what did this all cost, money money money.
drivers 1300 mk wood 400 mk misc. 300 mk screws & glue 200 mk drill 200 mk electric saw 150 mk grinding thingy 200 mk black finish 200 mk crossover filter 500 mk grand total 3450 mk
and that's without amplifiers! Huh, much more than I expected.
After testing the subwoofers with test tones, I realised my mistake:
70 mm vent-tubes are too small! 20 and 30 Hz gives really bad whooshing
noises from the tubes. I'll have to plug them, goddamn it :(
Aug 14 2001