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centerchannel68 · 04:11 PM

Alright, so we had to design a dispenser, and I chose to do a 'sound dispenser'. It was also a plastics project, so I had to use primarily plastic in it's construction. I originally wanted to do the cabinet out of wood, due to it's better acoustic properties and then having a vacuum formed front panel that acted as horns for each driver.... but that got SLAUGHTERED during critique for being too boring, so I went back to the drawing board and did a TON of thumbnails. I sketched hundreds, and settled on a 'pill shape' front end, with more a batmobile two humped back end, one behind each driver, but a guy in my class who builds a lot fo speakers says he's seen a lot of ipod products like that and that I should really try to make smoething different. Again, back to the drawing board.

Eventually I found a design that I really liked, and decided to wall mount the speaker above the display (after xmas I'm getting a 24" iMac to use as a main machine and the entertaniment hub. Out with TVs, in with big ass computers!

).

The front face plates are really thick acrylic, and the back pods are all vacuum formed. For the front panels I cut the acrylic on a scrollsaw, then used a hole saw, and a table router to chamfer t he edges of the hole. I then switched bits and used a 45 degree bit to 'bevel' the edges of the router (important later). The rear sections of the speakers were created by making a mold... I originally glued wood together, then used a wood lathe to create a dome that had a diameter just up to the length across the beveled front panel. Then I constructed a tail out of foam, and bondoed the whole thing,sanded it, repeat that process like 5 times to get it real smooth. The two pods are held together by a center acrylic section with massive bolts, which are also the terminals (I drilled them to accept wire, and used washers to crush the wire). So basically, the bolts that hold it together are doing double duty; strength and they're conducting the power to the crossover. The speakers were hi-vi 3" extended range drivers purchased for $8.95 each, and the tweeter was a rear mount style purchased for $4.60, and the crossover was made for 2 8ohm woofers and a 4 ohm tweeter (perfect) which only cost 59 centers, all from parts express. I spent more on the paint (carbon metallic) and bolts than I did on the actual audio parts, but that's okay. Why? **** speakers mounted properly sound better than good speakers mounted poorly. Each driver required only 4 bolts to mount it, but I drilled 4 other holes, and countersunk everything so there'd be 8 evenly spaced allen head screws holding them in.

I know this isn't 'normal' in terms of speaker design, but again.. I got slaughtered in crituque, so I created these while holding onto only 2 rules of audio: Build the cabinet as strong as possible and dampen it so it doesn't resonate. Also, be wary of paralell walls, as they'll reflect sound, creating funky loud spots... hence the copious amount of curves.

Here are the pics:

http://chicane.myftp.org/pics/center...r-Images/1.jpg

http://chicane.myftp.org/pics/center...r-Images/2.jpg
(remember it will be wall mounted)

Detail shot of all the wiring and bolts and trick construction for the wiring and all that:
http://chicane.myftp.org/pics/center...r-Images/4.jpg

The bolts suck together, but I used acrylic tube to shield each bolt, and a forstner bit to cut into both silver pieces to hold the tube securely.

The acrylic was lined with rubber adhered with super 77 spray adhesive, and I also used padding for a pillow instead of expensive audio padding. The best part? It sounds freaking fantastic!!!

I replaced my regular HTIB center channel and the difference is striking! Shell casings, dialogue, and anything that isn't a super low frequency has just so much more clarity, it's just freaking awesome.

I still need to seal the whole where the wires enter the pods, but already it sounds LIGHT YEARS ahead of my current HTIB center channel (which will be sold by friday morning, and then I'm starting to set up the quadraphonic system)

Aggressively good or bad comments welcome! Rip it apart if you like, but I'm pretty stoked about it.

Peace.

- Rob

More pics here: Rob's Badass Center Channel

PS: This is kinda version 1.0. I'm planning on doing another set, SIMILAR to this, but better designed, closer spaced drivers, and a bunch of other improvements that I'm getting from other forums. IF you're interested, let me know, I'm probably going to build at least 5 versions. Then when I'm famous it'll be worth a lot. ha! (joke)

PPS: An editor from stereophile magazine thinks it's dope.

Doofy · Dec 20, 2006, 07:47 PM

Sweet. LOL @ pic 2 - Kristen not very interested.

Atomic Rooster · Dec 20, 2006, 08:44 PM

Looks good Rob. Bitchin price.

imitchellg5 · Dec 20, 2006, 08:48 PM

Very nice looking.... kinda artsy too.

olePigeon · Dec 20, 2006, 11:01 PM

I really liked your vintage stereo setup. That was sweet.

OwlBoy · Dec 21, 2006, 03:54 AM

bad-ass tv.

-Owl

rickey939 · Dec 21, 2006, 09:14 AM

Originally Posted by OwlBoy

bad-ass tv.

-Owl

imitchellg5 · Dec 21, 2006, 10:39 AM

Originally Posted by OwlBoy

bad-ass tv.

-Owl

It will be badder when he gets his 24" iMac.

Dark Helmet · Dec 21, 2006, 11:17 AM

Ahh good old cinder block shelves.

imitchellg5 · Dec 21, 2006, 11:44 AM

You guys are so olde skool, I use Mac Classics!!

centerchannel68 · Dec 21, 2006, 12:17 PM

Originally Posted by Dark Helmet

Ahh good old cinder block shelves.

Those are going to the basement soon... I'm building an entertainment center/desk outta birch plywood.

Goldfinger · Dec 21, 2006, 12:29 PM

I like it. Looks a bit weird but I like it. And cheap !

I'm always thinking about building my own front speakers to replace the ones I have right now. But, I'm not sure if my technical knowledge is adequate.

centerchannel68 · Dec 22, 2006, 02:56 PM

Thanks. Anybody interested in buying a center channel that looks similar to this? It'd probably be around $100....

Wiskedjak · Dec 23, 2006, 12:08 AM

Are there specific characteristics to centre channel speakers? I've got a pair of Apple Pro speakers that I've been thinking of turning into a centre channel.

turtle777 · Dec 23, 2006, 02:57 AM

Cool, thanks for sharing

-t

awaspaas · Dec 23, 2006, 12:56 PM

How on earth did your lady let you put that thing on your TV? Don't get me wrong, I think it's kinda cool looking, but not exactly a wife/gf-friendly design.

centerchannel68 · Dec 23, 2006, 01:01 PM

Read the thread. It's not going to be on my TV. Christ... it's kinda annoying whne people don't read the thread and just look at the pictures.

awaspaas · Dec 24, 2006, 02:01 AM

You really expected me to read all that? Try a few paragraph breaks.

RAILhead · 04:24 PM

Whoa -- did Rob just say whining was annoying? He must hate himself to bits!

Pendergast · Dec 24, 2006, 10:38 AM

That is a nice piece of DIY! Congratulations!

I like the idea of using the bolts for structure and connectivity. However, how does it sound? I figure that there must be some impedance involved? What kind of amplifier is driving them?

Also, I wonder about the resonance of the driver with the acrylic chamber? is the volume behind the driver sufficient?

I am no expert, but I saw a lot of diy stuff and those are questions I have seen often.

Myself, I have built a pair of speakers (fostex 206esr drivers) in their recommended cabinet and I know it is quite a job.

Nevertheless, what you did looks really cool!

centerchannel68 · Dec 24, 2006, 12:51 PM

Originally Posted by RAILhead

Whoa -- did Rob just say wining was annoying? He must hate himself to bits!

What's wining? Winning? Whining? Whinnying (sp?), like a horse?

centerchannel68 · Dec 24, 2006, 01:01 PM

The bolts have a resistence of 'zero'.... if you think about it, they probably conduct better than a wire. The crossover was designed for 2 8ohm woofers and 1 4ohm tweeter, so I think that means total it's 4 ohms.

What kind of amp? Why does this matter? Right now it's some technics home theater amp, but soon it'll be a technics SU-7700 I won on ebay.

The resonance? Pretty much nill. Like I said, I sprayed the interior of the 'pods' with super 77 spray adhesive, then put cut up pieces of rubber on them. I also used stuffing, to further reduce resonance. They're very solid, and they don't sound 'plasticy' like a lot of HTIB and boomboxes at best buy. Also, curved surfaces drastically reduce resonance, as the sound waves can't reflect back and forth much. They sound pretty decent actually.... I am gettng a funky bass note on one region, but I still haven't sealed where the cables go into the pods, so I'm guessing it's because of that.

The volume is probably NOT sufficient. I cut out the front panels first, without realizing that I had to make the diameter of the 'dome' for the vacuum.. basically, in order for the dome to be the right diameter and still have the right draft so the plastic could be removed, I couldn't make them super deep, because the angle would have been too close to vertical, and the plastic would have never come off.

There are a lot of things I'd do differently the 2nd time around. Increasing the volume would be the biggest factor.... I'd also use 4" drivers instead of 3" drivers, and make the ports a tad bigger.

Thanks for the compliments!

cjrivera · Dec 24, 2006, 01:35 PM

Originally Posted by centerchannel68

The resonance? Pretty much nill.

What's nill? nil?
Definition of nill - Merriam-Webster Online Dictionary
nill - Definitions from Dictionary.com
nill. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Nill - OneLook Dictionary Search

(

Sorry man, couldn't resist. Nice speaker by the way...)

centerchannel68 · Dec 24, 2006, 02:40 PM

Har har. NIL. There. Dork.

SSharon · Dec 26, 2006, 01:59 AM

Hey Rob,
Good work on those speakers. I know you put a lot of time into these DIY projects. I also finally got around to installing the pci card I got from you. Everything works great.

Kevin · Dec 26, 2006, 10:50 AM

What is wifey making there in the background?

http://chicane.myftp.org/pics/center...r-Images/2.jpg

She needs to start her own thread!

centerchannel68 · Dec 26, 2006, 11:00 AM

Ssharon: Sweet. Glad everything works okay. I'm still without a main computer and using this beat up tibook for now. Ugh. I hate laptops and trackpads, you can't do any real work on them.

Kevin: She made a scarf for my sister, for Xmas. It was orange, and super soft alpaca yarn or something.

Kevin · Jan 1, 2007, 12:13 PM

Aww doing good wifey stuff.