Hello all, I have been a lurker for a mere week or two, but have decided to build my own system.
I will start with my humble request. I would like to build a sub with the Kappa Perfect 12 VQ. I will probably use the MCM 300W RMS plate amp. But, I have no idea of how to design a box for the sub. I have looked at the rather extensive design outlayed in some previous posts, but with no demensions, I don't know where to begin. Also, what crossover network should I use. I plan on getting my parts from PE, but don't even know where to start. Can someone please help? BTW, I would like to use the sub enclosure as an end table by the sofa.
On a side note, I have been looking at speaker designs as well and have been intigued by the S.C.5.1 design as shown on the parts express project showcase. Any thoughts on these as both HT and music speakers?
I can't comment on the SC51 speakers. But as for the sub, I will point out that it can easily use 2x that power. It's an extremely high grade driver and all of it's manufacturer specs are very conservative. The 300 watt amp will clip well before you ever exceed the linear mechanical range of that driver - thus limiting your spl/dynamic by the amp, not the driver. This assumes a proper cabinet design of course.
As for specific cab design issues: a high excursion 15" passive radiator will work well or a regular excursion 18" will work well. A slot port will also work well - but it will have to rather large in cross section(something near 40 square inches in the cross section, and over 50 inches in length, requiring to you build a folded line in the cabinet.
I can help you with precise box/port dimensions, but I'll see if some one else will do this for your first - as I'm rather busy currently.
One very low cost alternative for 5.1 speakers that will perform remarkably well is the Behringer 2030P. They are about 130/pair. So, get 3 pairs and have an extra one. It is a very high quality speaker, ironically, better than most that cost 5x - 7x as much; I kid you not. It does need some very minor fixes to correct for standard mass produced shortcomings. Here is the list(15 minutes of work per speaker):
1) Replace internal acoustic stuffing with more material and a higher grade material(ideally 4-8 lb/ft^3 density rockwool board or fiberglass board). If you can't easily get it, I will mail some to you for very low cost(the stuff is CHEAP) if you are in the USA. PM me for details.
2) Fix vibrating metal can magnetic shield on woofer. Use liquid(NOT gel) super glue and squirt some generously around the seam where the can meets the driver - this will stop the vibration.
3) Fix air leak number 1. On the tweeter, where the tweeter motor connects to the tweeter faceplate, there is no seal between them. Use plain silicone sealant and squirt around the seam, being sure to also squirt around the base of the electrical leads.
4) Fix air leak number 2. On the plastic waveguide around the tweeter, there is no seal where the tweeter connects to the waveguide. Remove tweeter from the waveguide (
4 screws on the back) and use bluetack, rope caulk or speaker gasket puddy; flatten with your fingers and place small amounts on the ridges of the waveguide where it connects to tweeter. Re-mount tweeter and tighten screws. Scrape off excess putty on the front that squeezes out with fingernail.
While this speaker is super low cost, it has far better linearity and off axis response than most that cost far more money[1]. It has 1.25" MDF front baffle, 0.75" MDF cabinet, MKT film caps, very high power iron core inductors(
as opposed to the small ones normally used in low cost speakers that easily saturate at low power levels), cast frame woofer and relatively low distortion even when used at 100dB(
assuming an active crossover is used to limit LF, of course).
You can not DIY a speaker that has similar over all performance for cheaper(including drivers, cabinet, all costs, etc.).
-Chris
Footnotes
[1]
http://www.linaeum.com/productinfo/other/behringer_2030P/