Cohesive 893 center channel build

rojo

rojo

Audioholic Samurai
Thought I might upgrade my center channel with a horizontal Cohesive 893 from DIY Sound Group. I based that decision partly on limited availability of 3-way horizontal centers with available cabinet flat packs, but mostly because of the 893 center's impressive listening window response graphs.

Other than inserting sub drivers into pre-finished cabinets, I've never attempted a DIY build before.



As follows is my attempt to compensate for ineptitude with enthusiasm. Firstly, let me echo what every other DIYSG customer ever says about the superlative packaging of drivers and other stuff. Erich E. Tetris'd all the contents of the packages perfectly, adding padding where needed, and I'm pretty sure everything would've survived without a scratch even if it fell off the back of the truck.

Erich also recommended that I contact Joemar Abetong for a PCB to help me assemble the crossover. You can see the PCB in the upper right corner of the following photo. Since I had some spare PC motherboard standoffs, I figured that'd be a great way to mount the crossover.



I nearly set fire to the thing trying to cut the hole for the binding post cup. Is that normal?





Hole is cut and the enclosure (minus front baffle) is assembled. I could've used more clamps or a finishing nailer or something, but it's close enough for government work. I even captured my toes in the pic for you pervs.



While waiting for the cabinet to dry, I assembled the crossover on Joemar's PCB. It was a worthwhile purchase. I highly recommend contacting him if you're planning to complete a DIYSG project.



The mounting looks a little off-square in that pic because the PCB was laid out for an electrolytic 50uF cap, but my DIYSG kit shipped with a much larger 50uF polypropylene cap. Joemar said he would modify the board for future designs and offered to ship me a replacement. I told him not to bother. What I have works well enough.

And now, a story in pictures:







I also used spray primer on the cabinet, but I didn't think to snap any pictures. Here's the cabinet with a couple coats of Glidden Peachwood oil-based semi-gloss enamel.



Krylon silver metallic. I strongly recommend against using this on your project. It does not sand well at all. But my project budget is blown, so I'm sticking with it.



Dramatic lighting!



Third and final coat of Peachwood. Yeah, you can see my crappy hole cut here. Neophyte tip: cut your hole from both sides and meet the cut in the middle.



I let the Peachwood coat dry for a full week. Now it's time for the faux wood grain finish. To practice, I started on the bottom of the cabinet. I splashed a thimble or two of paint thinner on the cabinet and spread it around using the cheapest, crappiest chip brush I could find from Dollar General. I then dipped the thinner-sodden chip brush into Glidden Old Redwood and spread it around the surface of the box. Once fairly evenly distributed, I dragged the bristles in one direction, row by row, paying special attention to make the lines slightly imperfect. It's those imperfection that make the texture plausible.





Bottom and back done. From here on out, my technique matters more.



Not too shabby, if I don't say so myself. After drying, time to insert the crossover and glue on the front baffle.





After a couple coats of poly:







I was torn between spit sanding again for the 100th time and adding a couple more coats of poly, but @afterlife2 talked me out of it. He said it was good as-is. Who am I to argue?

Anyway, the box is stuffed with chunks of an $8 mattress pad from Wal-Mart, the drivers and binding post cup are loaded, and the fully assembled center channel is in my system. The finish came out a little redder than I anticipated, but it's still a pretty decent match to my mains.





Initial listening impression: it sounds pretty good so far. With my previous center, occasionally voices sounded a little boxy. I haven't heard boxy sound from this center so far. More listening is needed before I develop a full opinion.
 
afterlife2

afterlife2

Audioholic Warlord
Dang they match the bookshelfs near perfectly to my eyes. Cheer/Applause. Fantastic 1st effort. Looking forward to how they sound after a week or so.
 
rojo

rojo

Audioholic Samurai
Dang they match the bookshelfs near perfectly to my eyes. Cheer/Applause. Fantastic 1st effort. Looking forward to how they sound after a week or so.
It's a trick involving poor photography, sketchy lighting, and reduced image resolution. :)

Sounds pretty transparent. I just re-ran Audyssey setup a little while ago. I haven't re-flattened my subs yet. But with the rough tuning it's still a pretty excellent blend, and voices are as convincing as the original recording quality so far.
 
Swerd

Swerd

Audioholic Warlord
It's been a long time since there's been a DIY project here. Nice work, especially on the finish.

Do you know what the crossover frequencies are for woofer-to-mid and mid-to-tweeter?

It looks like you used a hand held drill with a hole saw to make the cut for post cup hole. High speed with that type of bit will cause the wood to scorch. Did you use a slower speed? You can probably have better results with a drill press – more torque at lower rpm. Or better yet, a router.

I take it that the driver holes came with the kit :D.
I nearly set fire to the thing trying to cut the hole for the binding post cup. Is that normal?
 
TLS Guy

TLS Guy

Seriously, I have no life.
Nice first build. Let us know how you like it over time and how it blends. It looks like a really good value for money build.

Just after the super human effort of building speakers, at first they are always the best speaker you ever heard! Then reality sets in.

As regards, the listening window. The speaker you posted measurements from was built as a vertical speaker.



Your horizontal layout will very significantly alter the polar response graphs.
 
lovinthehd

lovinthehd

Audioholic Jedi
Nice first build. Let us know how you like it over time and how it blends. It looks like a really good value for money build.

Just after the super human effort of building speakers, at first they are always the best speaker you ever heard! Then reality sets in.

As regards, the listening window. The speaker you posted measurements from was built as a vertical speaker.



Your horizontal layout will very significantly alter the polar response graphs.
You sure about that? He has the center version....and Ryan talks about his measurements of same in that thread he linked....
 
rojo

rojo

Audioholic Samurai
It's been a long time since there's been a DIY project here. Nice work, especially on the finish.

Do you know what the crossover frequencies are for woofer-to-mid and mid-to-tweeter?

It looks like you used a hand held drill with a hole saw to make the cut for post cup hole. High speed with that type of bit will cause the wood to scorch. Did you use a slower speed? You can probably have better results with a drill press – more torque at lower rpm. Or better yet, a router.

I take it that the driver holes came with the kit :D.
The crossover points are around 500 Hz and 2 KHz according to this post.

I started the hole using an 18v cordless drill, but it didn't have enough torque to cut more than halfway through. That's when I switched to the corded Binford 3000 drill and started setting the rear baffle on fire. :) Oh, I'm sure it was never in any danger of igniting into a full flame, but the smell of smoking MDF was not pleasant.

Yeah, Erich includes a CNC cut front baffle with all his kits, even if you don't order the accompanying flat pack.

Nice first build. Let us know how you like it over time and how it blends. It looks like a really good value for money build.

Just after the super human effort of building speakers, at first they are always the best speaker you ever heard! Then reality sets in.

As regards, the listening window. The speaker you posted measurements from was built as a vertical speaker.
It seems to blend pretty well from what I can tell after listening for a few hours today. Erich actually tried to steer me toward other center channel options, as he feared there would be a glaringly different behavior between the dome tweets of my mains and the compression tweet of the 893. But I'm pleasantly surprised that dialog so far sounds like a pretty good match to the mains.

Re: listening window, Ryan Bouma labeled the following graph thusly. (The caps are his, not mine.)

tuxedocivic said:
Here's the important part. This is the horizontal 0, 15, 30, 45, 60 angles of the HORIZONTAL CENTER CHANNEL.


He then goes on to say ignore the 10K - 20K octave as he's still figuring out the software. But the important takeaway is the consistency of the graph shape at ever increasing angles. Whatever Audyssey flattens on-axis will remain relatively flat off-axis as well.
 
TLS Guy

TLS Guy

Seriously, I have no life.
You sure about that? He has the center version....and Ryan talks about his measurements of same in that thread he linked....
Yes, he posted the wrong picture. That was explained in a later post. He did measure the horizontal version.
 
lovinthehd

lovinthehd

Audioholic Jedi
Yes, he posted the wrong picture. That was explained in a later post. He did measure the horizontal version.
He didn't post a wrong picture, just not the one you apparently expected, he said as much about the pic unless you remember something before he edited that post back in September. He said in the post: "Just for fun, here's a photo of the VERTICAL version with a camera better than my iPhone
I'll grab a pic of the horizontal center channel later."
 
S

shadyJ

Speaker of the House
Staff member
If there is one guy who can pull off a horizontal mtm center, it is Ryan. He was a big help to me in getting my own speaker measuring system going. The lengths he will go to to get accurate measurements of his speakers are very impressive. I am sure your center sounds terrific.
 
rojo

rojo

Audioholic Samurai
If there is one guy who can pull off a horizontal mtm center, it is Ryan. He was a big help to me in getting my own speaker measuring system going. The lengths he will go to to get accurate measurements of his speakers are very impressive. I am sure your center sounds terrific.
Yeah, you're not kidding about the extraordinary effort he puts into measurements. Check out the first post of the 893 dev thread. He's got his prototype on top of an 8-foot step ladder to avoid ground reflections. That's true dedication to his craft.

My center isn't an MTM though. What would you call it? W(MTM)W? It's a 3-way in any case.
 
S

shadyJ

Speaker of the House
Staff member
Yeah, you're not kidding about the extraordinary effort he puts into measurements. Check out the first post of the 893 dev thread. He's got his prototype on top of an 8-foot step ladder to avoid ground reflections. That's true dedication to his craft.

My center isn't an MTM though. What would you call it? W(MTM)W? It's a 3-way in any case.
He will go to greater lengths than that to procure accurate measurements. He knows that an 8 ft ladder will only get you get measurements to maybe 80 or 90 Hz or so, because of ground reflections. So he has measured speakers off the ground at heights of 20 ft, where he doesn't even have to window out ground reflections.
 
D

Diesel57

Full Audioholic
Really really nice work, ideal fit and I hope it meets your expectations, nice touch Rojo:)...
 
speakerman39

speakerman39

Audioholic Overlord
Very nice Rojo! Looks fantastic! Bet it sounds just as good as it looks too! If this is really your first build, then all I can say is that you got skills my friend! :D:D:D

Cheers,

Phil
 
D

Diesel57

Full Audioholic
Well, Rojo, after deliberating, the decision came to this...you got the job...I will be placing a order Friday, keep in mind that I'm letting you be my friend:)...Once again Great job!!!
 
ARES24

ARES24

Full Audioholic
Nice looking build. I have never tried a faux wood finish. I have tried cheap veneer and wish I had tried your approach.

As for the burning wood with the hole saw, try pouring water on the bit slowly while drilling :p Actually judging by a quick look at the photo I think that the hole saw you used isn't high quality. Better hole saws generally clean out better. It is the lack of dust removal that is the problem, even really good drill bits will burn if not used carefully. The easiest fix is to simply remove the sawdust as soon as it starts to well up.
 
rojo

rojo

Audioholic Samurai
Nice looking build. I have never tried a faux wood finish. I have tried cheap veneer and wish I had tried your approach.
I got the idea from this cat (sorcery starts around 02:45). My approach took a month. I can't help but feel that veneer + stain + poly could've been done in 1/4 the time. But at least this way I have no worries that the edges will ever chip or peel, no matter how often the speaker is moved.

As for the burning wood with the hole saw, try pouring water on the bit slowly while drilling :p Actually judging by a quick look at the photo I think that the hole saw you used isn't high quality. Better hole saws generally clean out better. It is the lack of dust removal that is the problem, even really good drill bits will burn if not used carefully. The easiest fix is to simply remove the sawdust as soon as it starts to well up.
Yep, my hole saws are cheap pieces of crap. I got tired of buying individual hole saws of specific sizes for various projects, so I just bought a kit with every size I would need, ever. But at least they make holes... eventually.
 
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rojo

rojo

Audioholic Samurai
I'm digging this speaker more the more I listen to it. There's no longer the same boxy sort of sound I occasionally heard from my previous center. While listening to the Presidential debate last night, it sounded a bit shouty at times. But that could be because there was actual shouting going on. I had no trouble understanding any of the dialog, though -- including when Chris Wallace asserted that he is, in fact, not a potted plant.

I still haven't had a chance to perform a meticulous tuning of my system, so I'm reserving a full opinion until later.
 
KEW

KEW

Audioholic Overlord
Cheap hole saws and mdf are not a good combination. If it is what you have, it might be best to drill from below so gravity will clear the dust (or a high velocity fan). Either way, you should be outside so you don't get a layer of dust everywhere. Between the cheap hole saw which "rubs" a hole in the mdf instead of cutting it cleanly and the saw groove getting loaded up with mdf dust, you have gobs of friction happening at the contact surfaces. Even a decent hole saw would benefit from clearing the mdf dust, that stuff expands/self-replicates as you liberate it from the panel!:(
 
Grassy

Grassy

Full Audioholic
Very nice work rojo,it looks amazing mate and hope you get a lot of enjoyment from it.:cool: Very cool indeed.
 
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