Dipolar rear surround speaker

**Owen Bartley** · **12-24-06, 08:40 PM**

Construction has finally begun on my dipolar RSS. I am building the one from the Loudspeaker Design Cookbook in the provided system designs, and it will be the only rear surround in my 6.1 setup.

Merry Christmas (eve)! I got started this evening and made some dust, cutting out all the panels for this project. It was a bit of a pain to get the angled front baffle measured properly and cut to fit, but it turned out pretty well in the end. My father was good enough to help me out and it was nice to have an extra pair of hands, not to mention a lot more experience in the woodshop.

We started cutting the easy panels, and then decided to use the trusty pocket hole jig to assemble the top, bottom, and back in order to measure, mark, and test fit the angled baffle pieces. Once we got it all together I realized I goofed in my calculations and made the box a bit deeper than it was supposed to be, but a little extra internal volume can't be too bad a thing, and it gives me more room to mount the crossovers.

Next phase will be cutting all the required holes and assembling the crossovers. A note about that: I have NO idea how to actually physically hook up the crossovers! By looking at the diagram (attached), I think I'll be able to figure it out, but I'll probably post pics before final assembly. What type of wire should I be using for connections with this? Stranded or solid? What gauge?

I'll get to the next bit after Boxing Day I think, since I'd like to have this puppy up and running in the new year. Hope everyone has a great holiday, and I'll be back with updates soon!

p.s. These were taken with a camera phone since my regular digital had no batteries. I'll do better next round.

**Sonnie** · **12-24-06, 10:21 PM**

Very interesting... nice work too...

**F1 fan** · **12-25-06, 07:37 PM**

Looking good so far Owen

Using the pocket srews was a great idea.

As far as wire you don't need anything fancy ,either solid core or multistrand is fine as long as it is at least 18guage. I usually use inexpensive 16 guage oxogen free speaker wire to hook up drivers to the crossover and input connectors.
If you have any questions about crossover wiring let us know.

**Owen Bartley** · **01-02-07, 08:21 PM**

Made a little progress today and got the crossovers mocked up... but here is where I need some serious help.

1) Do inductors have an "in" and an "out"? I guess in other words, are they directional, or does it not matter how I have them hooked up?

2) I'm hoping that someone can tell me from the pics attached how exactly to connect these things. I have the layout ok, but I have no clue how to make the actual connections. (OK I have some clue but I'd rather do it right the first time). If someone could MS Paint me some lines showing where to connect the wires, input cup, and speakers on the 3rd diagram showing both crossovers I would be very grateful.

I have attached pics showing the front and back of each crossover, as well as one with the front of both crossovers together (they're a bit dark, but should be viewable). You can refer to the schematic and layout diagrams up in the first post at the top of the page.

**F1 fan** · **01-02-07, 08:51 PM**

All your components are non polarized including the inductors so they can be hooked up either way.Just be sure that you remove some of the coating at each end of the coils or you won't be able to solder them.Scrape it off with a knife or use sandpaper.I dont think I have Ms paint so I can't draw you lines but if just connect each component as in the schematic you should be OK .I will take another close look at the pics.

**F1 fan** · **01-02-07, 09:00 PM**

Ok I guess I do have Ms paint now I just have figure out how to use it.

**F1 fan** · **01-02-07, 10:03 PM**

Sorry its a bit sloppy but it might help.

**Owen Bartley** · **01-02-07, 10:26 PM**

Fred, that's awesome, thank you! I'll get soldering tomorrow.

**F1 fan** · **01-02-07, 10:50 PM**

Your welcome.

**Sonnie** · **01-02-07, 11:02 PM**

Excellent illustration Fred...

**Exocer** · **01-03-07, 01:33 AM**

Owen, cool project.

F1, excellent job with the illustrations

Wish I had someone like you around when doing my first project.

I am not completely sure if each speaker will have only a single inductor or not. If not, place one vertically and one horizontally to avoid interference between the two.

Other than that everything looks good to go!

**F1 fan** · **01-03-07, 05:52 PM**

Exocer does bring up a good point about the placement of the coils.Even separating the two crossover sections by several inches will reduce any mutual coupling between the inductors.

**Owen Bartley** · **01-04-07, 09:41 AM**

Thanks again for the help guys. Fred, your diagram helped me a ton, this being my first attempt at building any kind of circuit since high school. Exocer, thanks for the tip on inductor placement, I turned the small one up on its end without much tinkering underneath.

Here are a few more pics of my progress last night. I got the crossover all connected and soldered, but I haven't tested it. I built on 2 seperate boards, which was my interpretation of the plan, then decided it would be easier if they were just on one, so I hot-glued them together using a few spacers to keep the connections and wires up off the bottom when it goes in. We also drilled out the tweeter holes.

**F1 fan** · **01-04-07, 06:36 PM**

Glad the diagram helped.

It is coming together nicely.

**Owen Bartley** · **01-06-07, 03:38 PM**

Did a little more work today. I got the front baffle and rear input cup cut out, and I cut the Sonic Barrier foam to shape and size for the inner walls. I screwed up once or twice on the sizing, but nothing serious, and it will all be inside anyway. Next up... driver mounting and testing I think!

Oh, we cut the front baffle on a bit of an inward angle so the screws will have a little more to grip into. I wanted it pretty tight, so i turned out I had to notch out the top and bottom to fit the speaker connection and a little square protrusion up top. But we got a good snug fit in the end. And I know, I'm going very slowly!

**Owen Bartley** · **01-07-07, 10:16 PM**

I made some more progress tonight. I wired everything up, and even though it got a little bit confusing, I think I managed to do it all correctly. I used spade connectors for the speaker and terminal cup ends, and it all seemed to work pretty well.

Once I had the wiring done, I brought the unassembled speaker upstairs and plugged it in place of my normal front right speaker and gave a quick test listen. Apparently my crossover does work, because the tweets get the highs and the mid gets the mids, and it didn't sound too terrible even with tweeters hanging out the sides and the woofer sitting on top of the box (I didn't want to screw anything in). I did notice some up-close tweeter hiss, and I wasn't very happy about that, until I went and checked at the regular left channel Monitor 7, and it had the same amount, so it must be coming from somewhere else in the chain. It's very low and can't be heard more than a foot or so away.

With that small victory, I headed back to the workroom and did the final cabinet assembly, using glue, clamps, and a brad nailer (in addition to the original pocket holes screwed and glued on the top and bottom). There were a few places I'd made cutting mistakes, or where the screws pulled a bit, so out came the filler, and tomorrow I should be able to sand and start priming. The finish is just going to be a basic semigloss black.

**Owen Bartley** · **01-14-07, 08:42 PM**

...and she's done. This is a few days worth of work here and there, with much sanding and filling of holes and cracks and priming and sanding and filling some more. But it came out pretty nice looking in the end. I forgot to take a picture of the primed speaker, and I also forgot to take one just before putting the woofer in to show the stuffing, but I did put some polyfill inside in addition to the foam on the walls. An unintended bonus is that the cabinet finish is an almost exact match to the woofer cone. I'll take some better non-phone pics later this week.

Initial impression... it might not be the best mix with the current direct radiating surrounds. It seems more subdued and quiet, much more subtle, which I guess is the idea. It seems like it would do much better in a corner, instead of dead center where it is. But overall as a project I'm happy with it, and I'll give it some break in time, and see how it sounds a few movies from now.

Thanks for all the help, tips, and good advice!

**Owen Bartley** · **01-15-07, 07:30 PM**

Better pics of the finish. I used the same Rustoleum Hammered Metal paint as I used on my sub. I probably should have left it with just a single coat, because it lost some of the effect, but I wanted to make sure I had full coverage. I do like how it almost perfectly matches the speaker cone, and I'm not in a big rush to make the grille now.

**Sonnie** · **01-15-07, 08:05 PM**

Wow! You have truly built a fine looking speaker there Owen. I am thoroughly impressed...

**F1 fan** · **01-15-07, 08:58 PM**

It looks great Owen,that Rustoliem makes for a nice textured finish.You must have spend some time preping the box before painting because you can't see any of the joints.

**01-16-07, 08:53 AM**

Can't beleive my eyes!!! Absolutely brilliant! Very good. Bravo!!

How well does it sound??

**Owen Bartley** · **01-16-07, 07:10 PM**

Thanks guys! Yes, there was a lot of prep before I painted, and it still isn't perfect, but it's good enough for me.

Ed, it sounds good, but it is a lot quieter than my other surrounds (Paradigm Mini Monitor). I am kind of wishing I had done the sensible thing and made a pair instead of a single one, and I could swap them out, but I'm still happy with it as the lone Back Surround. I'll have to adjust the levels a little more, maybe down a bit on the Minis and up a bit on this guy, but he does deliver a nice diffused sound! I think they'd be great in a pair of SB's, in a smaller room.

**Eddie Horton** · **01-18-07, 05:26 PM**

Owen, that speaker looks outstanding. Great planning, great execution, and that jig for the pocket screws is too cool. One question, do you have a SPL meter to make sure it is level matched with everything?

**Owen Bartley** · **01-18-07, 10:07 PM**

I do have one Eddie, I just haven't hauled it out yet. I did some quick adjustments by ear, and have only gone through a few quick scenes as a test. I might try to do some calibration on Sunday, depending how the weekend goes.

**kano32** · **01-19-07, 03:02 AM**

Great job. I also prefer a more difuse sound. Direct radiating speakers can sometimes be a distraction when employed in the sourround duty IMHO.

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