Lessons Learned When Building a Speaker

I have been building a 3-way center speaker for my home theater, because the Triangle BRC1 I picked was never delivered. It showed as in-stock and as shipping-next-day at Electronics For Less, but alas.

Screw that, I will design and build my own speaker, with blackjack and hookers.

And unlike the Triangle, my speaker will be a proper 3-way one. A driver dedicated for the low frequences, one for the high frequencies, but also one for the middle frequencies.

For my design, I kinda winged it. I didn't simulate wave propegations, or accurately calculate volumes.

Lessons learned:

• MDF makes for excellent material. I complimented it with Oak sides for a nicer look.
• You cannot use a water-based paint on MDF. I find that Rust-oleum LEAK SEAL is excellent: it puts a rubber coat on the MDF. It is bumpy though, not for a smooth finish. But I like it.
• Home Depot will make excellent saw-cuts for free (12" and up.) But if the saw-operator is an under-trained teenager, you get crooked pieces.
• Ryobi $59 circular saw is straight up crap. I returned it. It's not even safe. It will always kick back violently. You get what you pay for.
• Those hole-saws that you put on a drill, work just fine. But it will not make those fancy recessed holes that a router could.
• Parts are plenty and cheap at AliExpress, and the seller (I used HIFIDIY) will guide you if you need help.
• Mid-ranges are harder to find than tweeters and woofers.
• Learned by mistake: don't order a sealed mid driver. You are building a pressure chamber from MDF, don't undo that with a sealed driver (other than tweeter.) I had to order a second mid range driver to correct this, which I sourced in Canada for faster shipping.
• Drivers have a preference on how to be used: Bass-Reflex (ported cabinet) or Acoustic Suspension (sealed cabinet.) There is an online calculator for this.
• Try to match up the sensitivities of your drivers. If one of the three is very sensitive and others are not, one frequency band will be too loud. And this is probably obvious, but each driver should be flat-ish in the range that the cross-over will give it. And of course, you do not need "full-range" drivers. Stay away from those, because you are building a 3-way, aren't you?
• Sealed cabinet is easier to get right than a ported cabinet, which is more finicky. And you should probably build separate sealed chambers for mid-range and woofer.
• Seasoned audio DIY people will try to talk you out of designing your speaker, and get a carefully planned kit instead. I say hog-wash: go for it! It's a bit like a stock portfolio manager: A pro is nearly as likely to get it wrong as an amateur. Also, making mistakes and learning is fun. I find that high end audio is some Science with mostly Art thrown in. Sometimes it works, sometimes it doesn't. Just roll those dice yourself.
• Drivers often come without a gasket. To make your own, get Duct Seal from your hardware store. It is dirt cheap and works great.
• I wish I had known this, but: Don't buy those connector boxes for the binding posts. Just buy two loose posts, and dril a small hole for each. If you really have to get a box, get one for a circular hole, not a rectangular one.
• Off-the-shelf 3-way cross over works just fine, despite their cheap price. You can save yourself a lot of time (and possibly troubleshooting) by getting a pre-built cross over.
• The closer you can place your drivers to eachother, the less likely you will get out-of-phase cancelations between them. Especially for audience not dead-center in front of TV.
• Get good glue-clamps.
• Don't embark on this if you do not have carpentry skills. It's just a rectangular box, but even making a rectangular box requires skill.

To my layman ears, the speaker sounds great, and at least as good as the commercially built bookshelf speakers I use with it.

Parts list:

• Kasun 1635C 3-way crossover at 1300Hz and 4800Hz.
• KS-167S woofer.
• Q1N 4 inch tweeter.
• SEAS PRESTIGE MCA12RC 12cm mid range.
• 3/4" oak panels, 0.5" MDF, glue, duct seal, driver screws, rust-oleum leak seal, binding posts, wire, solder.