DIY Sound Group Fusion-8 Alchemy build

borism · « **on:** 23 Dec 2015, 03:09 pm »

My son started college and to my surprise (he never showed much interest) he asked about a sound system for his dorm room.

This led me to thinking about relatively inexpensive starter systems and combine it with some DIY activity. I came up with a small integrated amplifier - the Dayens Ampino, a DA converter for computer audio files and streaming - HRT Streamer III and DIY monitor speakers. Since I have no woodworking skills it had to be something with a flat pack available and, given the 25 w/ch amplifier, with relatively high sensitivity (have to support some party functionality). This narrowed choices down quickly.

That's how I came upon the DIY sound group's offerings. The Fusion Alchemy is a very interesting speaker that uses a waveguide and compression driver and an 8 inch woofer. It only goes down to about 60 hz and is intended to be used with a subwoofer but has a rated sensitivity of 94 db.

The kit was shipped within a week from ordering. It was packed incredibly well. Since my son is back from school we started assembling the cabinets yesterday.

Have to say that the flat packs of Baltic birch plywood are precision cut and very easy to assemble.
To be continued...

gab · « **Reply #1 on:** 23 Dec 2015, 03:24 pm »

Designed by one of the best - Jeff Bagby

gab

jk@home · « **Reply #2 on:** 24 Dec 2015, 01:49 am »

I'm currently building a couple of 18" Ultimax sealed subs, using the 4 cubic foot boxes supplied by DIYSG. I agree, precision cut flat pack and the packing was excellent. They are the outfit that supplies the (same) boxes to Parts Express, for the driver/flat pack bundle kits.

How do you plan on finishing the cabinets?

borism · « **Reply #3 on:** 24 Dec 2015, 03:09 am »

Hi JK,
I was planning to just use black duratex. This should stand up to some dorm abuse.
Here are some updated images. The crossovers are installed and one speaker has acoustic foam.

mresseguie · « **Reply #4 on:** 24 Dec 2015, 01:30 pm »

They're looking good! I used a product that is very similar to Duratex for a pair of DIY speakers and I've found the finish to be very durable. It's exactly what your son needs.

I hadn't realized DIY SG's cabinets were such good quality. Of course, if I had simply called their number, I probably could have learned a few things. Thanks for posting your build. It makes me want to build a pair of speakers.

Michael

borism · « **Reply #5 on:** 24 Dec 2015, 06:09 pm »

Thanks Michael! Since I don't have much of any woodworking skills I decided to go with the easy option.

The project is moving at a brisk pace. Due to the Holiday my son and I have plenty of time. In addition, this is an easy kit to build. The quality of the parts is excellent.

The baffle was a precise fit.

jk@home · « **Reply #6 on:** 25 Dec 2015, 02:08 am »

Good deal. I will be using Duratex on mine also. It is tough stuff. One word of warning, make sure you let the Duratex cure completely before mounting the drivers. I have one sub that the stuff wasn't 100% cured, and put the driver on. A few years later, tried to remove the driver, and that thing is stuck to the cabinet.

I would use some sort of thin foam gasket material between cabinet and driver, to prevent this.

borism · « **Reply #7 on:** 25 Dec 2015, 02:39 pm »

Thanks for the tips JK!

The baffles are on. Sanding and painting are next. JK, did you dilute the Duratex with additional water as some people recommend?

jk@home · « **Reply #8 on:** 25 Dec 2015, 04:31 pm »

Looking good. No I've never diluted the Duratex. I would want it to go on as heavy as possible, but without runs. After you sand the boxes real good (do it outside, cause of the MDF dust), if there are still some small gaps in the joints, you can fill them in with spackling. But I've read that one should then prime those spots with a latex primer before the Duratex coating.

Here's a video by the folks who make it:

https://www.youtube.com/watch?v=iuav56tGIE4

borism · « **Reply #9 on:** 26 Dec 2015, 05:46 pm »

We just finished the first coat of duratex and while it looks very interesting the finish is a little rougher than I was hoping for. I will add a little water to the paint before the second coat. That is supposed to decrease the viscosity and make the surface a little smoother. We'll see...

JLM · « **Reply #10 on:** 26 Dec 2015, 07:48 pm »

Looks like the finish on my Hsu VTF-2 sub. Very rough, can't clean it - everything snags.

But do wish more audio kits were available. 35 years ago I built transmission line bass cabinets (everyone says they're hard to do, but they're not), and Hafler pre/power amps. Back then veneering was a royal pain.

Big congrats on finding a father/son project!

borism · « **Reply #11 on:** 26 Dec 2015, 10:25 pm »

Thanks JLM!

Well lightly sanding the rough 1st coat, diluting the duratex with a little water and using a smoother roller worked great. The finish, while still textured is actually smooth to the touch.

Folsom · « **Reply #12 on:** 26 Dec 2015, 11:02 pm »

I always wondered what those sound like...

Guy 13 · « **Reply #13 on:** 26 Dec 2015, 11:11 pm »

Sorry

gab · « **Reply #14 on:** 26 Dec 2015, 11:16 pm »

Quote from: Guy 13 on 26 Dec 2015, 11:11 pm

Sorry

Guy13 - you have actually heard them?

gab

rajacat · « **Reply #15 on:** 27 Dec 2015, 05:20 am »

I suspect they'll sound quite good. Waveguides and pro woofers can make excellent sound.

Jeff Bagby is well regarded.
They could be easily tweaked with fancy caps and no-rez. Both inexpensive and well designed.

Folsom · « **Reply #16 on:** 27 Dec 2015, 05:42 am »

Quote from: rajacat on 27 Dec 2015, 05:20 am

I suspect they'll sound quite good. Waveguides and pro woofers can make excellent sound.
Jeff Bagby is well regarded.
They could be easily tweaked with fancy caps and no-rez. Both inexpensive and well designed.

I've become quiet interested in waveguides, but not so much in less refined drivers. Geddes's discussion on how controlling high frequencies really makes it clear what the value of waveguides are.

Good call on no-rez

. I have no idea why it isn't the standard.

jk@home · « **Reply #17 on:** 27 Dec 2015, 11:31 am »

Quote from: borism on 26 Dec 2015, 10:25 pm

Thanks JLM!

Well lightly sanding the rough 1st coat, diluting the duratex with a little water and using a smoother roller worked great. The finish, while still textured is actually smooth to the touch.

Looking good. What kind of roller did you use? I remember when I did my other subs, I first used truck bed coating, that was a rough surface. Sanded it down some and recovered with Duratex. Not rough at all, just bumpy but still cleanable.

Anyway those look dorm proof.

JLM · « **Reply #18 on:** 27 Dec 2015, 12:39 pm »

Great work! Wish I could hear the finished product.

And without the fancy finish perhaps the dorm thieves will pass them by. I say the same for my Ascent Acoustics CBM-170's, plus the 170's are portly shaped (but I still love the sound they make for $350/pair).

I had stupid nice (LS3/5a clones) in the dorms back in the 70's and no one touched them while glitzy mass market stuff was constantly lifted.

borism · « **Reply #19 on:** 27 Dec 2015, 01:33 pm »

Thanks all!

Rajacat, I am sure they could be further tweaked but at this point I just wanted to go with the basic build and not add to the cost. If they survive the dorm environment (as JLM pointed out) we can always go back.

JK, I just used a smooth 4 inch roller from Home Depot. It worked great on the diluted second coat but when we tried it on the first coat without the added water for some reason that produced a very streaky coat. That's why we went with the duratex supplied very coarse roller.

Folsom, JLM, I can also hardly wait to hear them. However, we are leaving town for a few days and it will have to wait. At least the duratex will have some time to cure.