Vented Tritrix center speaker

[WilZirkle]

This is my second DIY speaker project the first being the TL Tritrix kit from Parts Express. I’ve been lurking here and on other forums for over a year now and decide I would post a little about this build. I know it’s been done to death but seeing a fresh build may help someone else decide to jump in.
I really jumped around a lot in making my decision to go with the Tritrix for my center, looking at a lot of designs. I built the TLs for my main almost a year and I am happy with them but I want something bigger eventually. My favorite speakers I own have always been by Klipsch, but I dreamed of replacing them with B&Ws. Anyway I’ve always been a DIY person and finding out that I could apply that to speakers…well you all know. So my DIY visions have danced around many designs but what it came down to was what I could afford right now that would work well with the TLs I already built.
I am basically following Curt’s original design with some modifications because I plan to set my TV on top of it. My modification to the design is that I will leave the front baffle the same dimensions but change the sides and back so that they are inside the top and bottom instead of outside. The top and bottom will be increased in width by 1.5 inches and depth by .75 inches so that the internal volume remains the same. I will add two small braces inside the box as well. I tried to sketch this up for everyone but it took too much time so you will have to wait for pictures if it’s unclear.
I will probably leave it unfinished for now as I have the TLs for the past year.
At this time I have one question about the port tube. The plans call for this to be a 2 inch port. I know people use PVC for this, is it 2 inch or 1.5 inch PVC? I got some 2 inch but that makes the outside diameter bigger than 2 inches.

[fbov]

The important port dimension is the ID, so you want the 2" pipe. I normally drill a shallow oversize rebate around the 2" hole and epoxy the pipe so it's centered. I then roundover from the outside to get a flare. The rebate size isn't critical, but use tape on the inside of the pipe to keep it centered, and prevent epoxy leakage.

I will ask why you've chosen vented? I don't see the advantage in a CC, as center channel processing usually includes a sub signal, and cc's are usually skewed toward dialog, benefitting from improved cone control in a sealed box. But this is DIY and you get to do what you want.

I'm not sure I understand about the top and bottom being inside instead if outside. As long as the box is 6.5" wide, you're good. Small volume changes are not audible, nor are small changes in port length.

However, integrating the speaker into your TV stand will cause noticable changes in tonal balance compared with free-standing placement. See if Curt's got an on-wall XO modification up his sleeve. This proved true for my build - CC has no BSC. Here's more:

http://www.salksound.com/wp/?p=42

Have fun,
Frank

[WilZirkle]

Thanks Frank, I went ported to try and better match the sound of my Left and Right speakers, they are both crossed with the sub and this one will be too. In reading previous threads it seemed like the way to go.

Not sure what to do about the BSC, the top of the speaker will not be flat with the surface of the TV but the bottom will be resting on the to on an old buffet with about 10 inches to the front edge.

Wil

[WilZirkle]

Question on the length of the port tube. Curt has it was 6.5 inches in the diagrams but is that extending 6.5 inches into the cabinet or 6.5 inches total including the bit that is glued into the back of the cabinet and will get rounded over (only 5.75 inches into the cabinet).

[fbov]

From the outside - functional length seen by the air, not length intruding into the box.

[WilZirkle]

Thanks again Frank, and I by the way that was an excellent article you wrote on BSC thanks.

[fbov]

You're welcomed, but that's Jim Salk's article... I have no connection whatsoever with Salk sound, aside from liking the sound of some of his products very much.
Frank