The Wildeman - MMTMM Sony buyout build

[bkeane1259]

My son and I are building a 2.1 system for his school's art room. This will replace the plastic PC speakers that are currently being used. Since I have 32 of the SONY BUYOUTS we decided to use some of them in a MMTMM configuration with PE's CONSTANT DIRECTIVITY HORN. The mains will be powered by the Lepai TA2020 and the low end will come from a small powered sub with the Aurasound NS8-385-4A 8" Woofer and Dayton Audio SA25 25W Subwoofer Amplifier.

The inspiration for the system name comes from the art teacher's name -- he is a staple at my son's school -- Mr. Wildeman. Corny, but whatever.

The towers will be wall-mounted and the sub will sit under a desk.

The towers will be sealed cabinets - 28" x 7" x 6.5" ~ around 0.5 cu. ft. Using 1/2" MDF and several internal braces. We plan to rear-mount the mid-bass drivers with roundovers on the driver cut-outs. We'll simply surface mount the horn. The cabinet will be pretty heavily stuffed with fiberglass.

The Sub is a basic 12" cube ~ 0.6 cu. ft. There will be a 2.5" ID x 8.25" long port. Should get an F3 close to 45 Hz.

Photobucket Gallery - WILDEMAN

[bkeane1259]

The planned driver layout:



Got the panels cut today. It's October 7th and we hit 81 degrees in Chicago -- a great day to work in the garage.



Got the mains clamped up -- the slice of MDF in the cabinet is not a sub-enclosure....it's just to keep the panels from bowing in under the pressure of the clamps. Even though I'm using these corner clamps, the pesky 1/2" MDF is pretty flimsy at 28" long. Probably should have used 3/4" MDF but since the speakers are hanging on a wall, we're trying to keep the weight down.



Glued and clamped the subwoofer cabinet. This will be a nice tiny 12" cube that nobody is going to see since it will be tucked away under the teacher's desk.



More cabinet work tomorrow. Might have a chance to get all the baffles done.

[greywarden]

Sweet, what are the plans for the crossover?

[mzisserson]

The sony's in-cab are super well behaved. KISS the x-over, you can almost run em' full range if need be. Looks great!

[bkeane1259]

With spare XO parts that I have laying around, I mocked up this crossover with the Constant Directivity Horn. I shot for a relatively low crossover point (2.1k) - a second order on the horn and a 3rd order on the woofers to keep them from hitting that 5k trouble area.



HOWEVER.....this was before I saw the awesome success that mzisserson had with his Lil' Brit, and the minimlaist crossover. For yucks, I'm going to try both and see what happens.

[bkeane1259]

Getting the front baffle done on the sub -- we're offsetting the woofer and installing the port on the front.



Gluing the front baffle on the sub -- no bracing just yet.



Test fiting-



Cabinets so far-

[bkeane1259]

Marking the front baffles for the Sony's and the horn. CTC spacing on the Sony's is 5.5". They will be rear-mounted. The tweeter will be surface mounted.



Ready to be cut-



I'm a lazy bastard so I just clamped the baffles together and cut them both at the same time. It actually worked perfectly for the woofer cuts, but the tweeter cutouts got lopsided and I had to retrim them.



Using the JASPER JIG for the circle cuts - it's awesome.



Test fitting the drivers on the baffle. The woofer cutouts will be rounded over later.

[nottaway]

Marking the front baffles for the Sony's and the horn. CTC spacing on the Sony's is 5.5". They will be rear-mounted. The tweeter will be surface mounted.



Ready to be cut-



I'm a lazy bastard so I just clamped the baffles together and cut them both at the same time. It actually worked perfectly for the woofer cuts, but the tweeter cutouts got lopsided and I had to retrim them.



Using the JASPER JIG for the circle cuts - it's awesome.



Test fitting the drivers on the baffle. The woofer cutouts will be rounded over later.

This looks real nice man, subscribed.

[Soundslike]

Look'in great so far. I'm anxious to learn how they sound. These Sony buyout builds are really interesting. I'm thinking I might have to get another case, so I'll have enough to experiment with the variety of designs so many of you are coming up with. Keep us posted...Great job on the string, by the way...

One think I have to add though -- your workbench is way too neat ....

[bkeane1259]

Already running into problems, but not major ones. I miscalculated the port dimensions. I originally modeled a 2” ID port which was to be 5” long, but the vent air velocity was above 20m/s, so I remodeled with a 2.5” ID port, which brought it down to 15.94 m/s – all good. But in my notes I forgot to extend the port to 8.25.” So now I have a 2.5” x 5” port installed (really well) which will need to be extended. Luckily, I have the room in the cabinet, so no worries.

I modified the original post to reflect the proper port dimensions.


Today I got the woofer holes rounded over and some of the cabinet bracing done. Gonna devote some real time to these tomorrow and I'll have more pics.

[bkeane1259]

Some minimal progress earlier today --

We're making the rear baffle removable (easy access to rear mounted drivers), so we installed some bracing to attach the baffle to---it also helps to damp the cabinet walls. The bracing is 1x2 hardwood -- a couple different varieties, but you get the idea. Since we're using 1/2 MDF with 28" tall towers, cabinet damping is definitely an issue.

In hindsight, 3/4" MDF would probably be better for this project, even though these buyout Sony's are not going to be hitting all that low in a sealed enclosure. I'd love to get some input from the pros on this.... With just this back baffle bracing, the knuckle rap sounds much better. Going to also install some horizontal dowels and then I think we should be good.

Somebody is going to say I should do window braces and that person would be right, but I'm trying to keep the labor hours as well as the price very low on this. Plus, my router skills suck.





Here are the front baffles with the rounded over woofer cutouts -- I used a 1/2" roundover bit and there's a very obvious cock-up that I'm not going to fix. ...too lazy. Oh, and I'm not talking about the horrific tweeter cutouts either. The tweets will be surface-mounted so that wont show.

[bkeane1259]

So after work I put on some music and dragged the 8 Sony's up to the dining room to do some frame damping and mounting gaskets.

When you flick these stamped baskets with your finger, there's a nasty ring that just says "problem." I don't know if the infamous 5k ring is related to the flimsy frames, but I decided to damp these things anyway....can't hurt. It's just labor and time really, because the damping material is dirt cheap.....

This is what I used to damp the drivers -- it's a poor man's Dynamat - Peel & Seal 6" X 25' Aluminum Roof Repair. There are variants of this....but I like the Peel & Seal brand. It's odorless, as far as I can tell, and I have used it extensively in cars, in speaker cabinets, on driver frames, even to eliminate rattles at my workstation. One thing to know is that once you apply this stuff, it ain't coming off.



The roll is 6" wide, so I cut 1 inch strips and then cut those strips into 3 pieces, so I had a bunch of 1x2 inch strips. This is a P.I.T.A., but it makes a huge difference. I did 8 strips per driver and when you flick the frame after the damping, it's a dead 'tink" instead of a reverberating "clank"....

Here's what one of the drivers looks like with the damping:



All 8 drivers done -- 64 1x2 inch strips of Peel & Seal later......



Next idea was to create a very small gasket around the perimeter of the driver frame. There is a very small "lip" on these Sony's...it's rather sharp as well, FYI -- anyway, I thought air leakage might be an issue, since we're rear-mounting these.

I used Permatex high-temp red silicone gasket maker for this, but my guess is you can use any silicone-based caulk for this. I had the Permatex stuff left over from a valve cover job on my son's car so that's what I used. I just ran over the driver lip and did a very thin bead. I did a $hitty job as I ALWAYS do with caulk.....I can't even do our bathroom tubs neatly. Anyway, I will let this cure so it forms a nice air-tight seal when we bolt the drivers on to the backside of the baffle.

[bkeane1259]

After doing this I thought it probably would be just as effective to use gasket tape...probably less of a hassle as well. Just thinking out loud, after the fact.

[greywarden]

Probably couldn't hurt to put a bead around where the surround meets the frame either...

[nottaway]

Looking real nice, I might have to copy this if it comes out goot.

Any reason you didn't minimize CTC on the woofs? Is it a non-issue?

[bkeane1259]

Probably couldn't hurt to put a bead around where the surround meets the frame either...

I thought about that, but I don't want any of the red gasket sealer to show thru the cutouts. Plus, I guarantee I would mess up several drivers with my sub-par caulking skillz. LOL.

[bkeane1259]

Any reason you didn't minimize CTC on the woofs? Is it a non-issue?

I could have pulled them about 1/4" closer but at that point, the frames would almost be touching and the roundovers on the cutouts would overlap.

Does it make a difference? Not for the way that they will be used -- up on a wall.

[davepellegrene]

After doing this I thought it probably would be just as effective to use gasket tape...probably less of a hassle as well. Just thinking out loud, after the fact.

I've been using Seal N Peel for mounting drivers. If you need to remove them it comes off fairly easy. Nice thing is once you get the driver back off you can peel the caulk off without to much trouble. Home Depot carries it. If it squeezes out between the driver and baffle it comes off pretty easy. It's kind of like silicone but not sticky.

Dave

[bkeane1259]

I've been using Seal N Peel for mounting drivers.

Thanks for that, Dave. That's a much better product for this application...and it's clear too!!

[bkeane1259]

Only had a little time to work on these today. Installed one cross brace in the sub. Even without the rear baffle on, the cabinet is fairly dead. I added a little Peel & Seal to the hardwood braces as well.



Added some of PE’s acoustic foam and I extended the port to the proper 8.25” -- I’ll add a little more foam after the glue on the port cures.



I’m using 3 dowel braces for the mains – for the side walls. After I mount the front baffle, I’m going to try to squeeze a couple more in between the front baffle and the rear baffle supports. That should be sufficient. I’m stuffing the cabinet heavily with fiberglass. Not really expecting too much bass out of these, rather I’m looking for good dispersion since they are going to be filling a classroom with sound.