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DIYSOUNDGROUP Cinema-8 Build Thread

7K views 24 replies 8 participants last post by  JDontee 
#1 ·
Cinema-8's arrived yesterday. Packaged well and the cuts are nice, so it should make for a clean cabinet build. The crossover.....well, that'll be tricky. I haven't looked at schematics since Physics in college, so this should be fun. I can't find any build threads for the Cinema-8's, only Alchemy-8's, so I decided to make this. I'll be posting pics as I go, and I'm hoping it won't take too long to build, but with football to watch and a 3 month old, it'll be tricky. Anyone who has advice for me as I go, I'd appreciate it. This is my first speaker build, so fingers are crossed. I've built some arcade joysticks for Hyperspin, so hopefully I can channel some knowledge from that....
 
#8 ·
That's okay, I mailed mine to Matt once I got them from Erich. Yeah, seems kind of silly, but that's how it works.
There have been several pictures of crossovers in other threads. Usually, you want to block out the numbers on the components. I can't at the moment, so here's the bottom (where all the important stuff is going on) of mine:
 
#15 ·
Here's this weekend's progress.

1. Began gluing the flat pack together. Started with the bracing, then glued the top and bottom with sides to finish. Fit really well together and only needed a little adjustment when clamping.

2. Sealed the internal with caulk. Probably not needed since it's ported, but I thought, what the hell.

3. Used some bed topper foam for treating the sides. I left one space open for now for the crossover, which I'm putting on the side at the bottom. I just used some spray adhesive and it seemed to do the job. The foam isn't very thick (1/2"), so I thinking I'll add some polyfill as well prior to screwing in the speakers.

Up next, I plan on applying plumber's putty to the waveguide. I'm not sure if it's needed, but I have seen others do it to decrease resonance. At the levels that I listen to, it's probably overkill, but I'm okay with overkill.

I'm still waiting to hear back from Eric H about a picture of a completed crossover. The schematic makses sense to me, but I'm just cautious since it's my first build. If they offered a completed crossover or at the very least a crossover board, I wouldn't have hesitated in buying it. For those interested in these speakers, maybe by the time you buy them it will exist.
 

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#16 ·
I added the plumber's putty to the waveguides. The plastic is pretty thick for the waveguides, so it might be overkill, especially at the volumes that I listen. The compression driver was a little tough to fit into the waveguide, but it eventually fit nicely. Up next, the crossover. Overkill seems to be the theme so far in this build. I had a friend who has his masters in electrical engineering look at my dryfit of the crossover and compare it to the schematic to check my work. Evidently my physics knowledge from 15 years ago is still strong.
 

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#18 ·
Plumbers putty works very well

Four years ago, I built my line arrays for the garage. Since it was one of those...why not, give it a try ideas, I used buy out woofers from Parts Express. The Sony woofers sounded fine but the stamped frames would ring like a bell when I tapped on them. Considering I was going to have 12 per box, figured the much higher SPL might get them ringing like the Salvation Army at Christmas.

Used plumbers putty on all the frames, let them set for a few days then put a zip tie around the putty on each leg of the woofers. Figured if any of the putty ever came loose, it won't fall off and damage multiple cones on the way down. Ran the speakers for a six months, took them apart to change from 2 way to 3 way and noted none of the putty ever got loose even after rather spirited testing. :cool:

Another way to "help" is to wrap thin string around the putty around the horn--call it audiophile waveline control if that helps. :rolleyes:
 
#19 · (Edited)
I assembled the first crossover today. Assuming that I did it correctly, it wasn't all that bad. I'd prefer having a board or have it done already, but all in all, not to complicated. I used some extra wood and 12 gauge wire thatl I had lying around. I would recommend using a smaller gauge wire. I glued the wires at the edges of the board so that it wouldn't stress the wire at the solder point wire installing the speakers, then I glued the board to the inside of the cabinet.

I used 1/4" bit to drills holes for the terminals and used a razor blade to cut a hole in the foam. They aren't centered in the speaker, so it won't be winning any beauty contests. I soldered the crossover wires to the terminal eye rings and connected them easily.

I drilled the pilot holes with 1/8" bit for all the drivers and added the gasket to the waveguide. Up next, polyfill, glue on front baffle, solder wires from the crossover to the drivers, screw the drivers to the baffles, then test them. After breaking them in for a bit, I'll use REW and post some frequency responses.

Edit: I'm way late in posting this, but I should clarify that one of the coils was not oriented correctly. That has been fixed, I just didn't get a chance to take a pic when I did it.
 

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#20 ·
And I'm done. Glued the baffle last night, added the polyfill, used wire connectors instead of soldering the wires to the drivers and screwed the drivers and waveguide to the baffle.

I decided to use wire connectors instead of soldering simply because I had 12 gauge wire and I was worried about getting tin on the cone. I tightened the crimps, so let's hope they stay on. If not, I can always solder later.

I hand tightened the screws for the driver/waveguide to the baffle. It just needed a good seal, and I didn't want to worry about cracking the plastic or stripping the screw.

I'm going to build the next one, which should go easily, and then break them in. Once they are broken in, I'll post some pictures of the response curves from various distances and axes and compare them to the HSU curves.
 

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#21 ·
I'm not sure if they are broken in quite yet. Here are some FR curves at 1 meter and at my MLP. Anyone have an idea about the lower frequencies in the graph for the 1 meter? I had both speakers powered (realized that I forgot to unplug it) My receiver is crossing at 80hz, no EQ (using direct), and the sub is obviously turned off.

-JD
 

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#23 ·
These speakers really fill my room. My space is about 2600 cubic feet. The speakers aren't in the final spot just yet. The Alchemy Center channel arrived yesterday and I'm in the middle of that build. I really wish I knew about diysoundgroup when I was building my theater. Here are some more measurements. Attached is Left, Right speakers with no eq at MLP and one of the right at 1 meter. I also attached one comparing audyssey to no eq. At this point, it's almost a toss up between no eq and audyssey to my ears. I'll let others comment on the curves. If I were to spend more money in my theater, it would be spent on more acoustic treatments. I feel like these speakers aren't being used to their full potential.

-JD
 

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#25 ·
These were single speaker measurements, instead of stereo at mlp. I'm in the middle of building my center channel with the alchemy 8 center. Once that is done and broken in, I'll place all my speakers in the final resting places and do some thorough testing. I've been speaking with Erich H about the crossover point, and if it still exists once I place the speakers at the final resting spot, and if Audyssey can't correct it, I'll try to change the polarity of the compression driver. I'm not trying to chase the flattest curve, so if the polarity change yields a less desirable experience, I'll change it back. As of now, these speakers sound amazing for music. I'm excited to match the center and experience it for movies.
 
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