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Dominick22

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I just finished this center channel. The parts and ideas come from partsexpress.com. This is my first speaker project so I wanted something simple plus I dont have many "shop" tools like table saws to use...just very basic ones.

Anyway, This by no means compares to the Martin Logan Theater i you see in the pic which is there to conceptualize the size, but I am happy with it, and for the money I spent, I would consider this project an economical success. Its smaller size makes it good for the bedroom...and so the battle with the wifey begins!LOL

I can give further review of critical listening if anyone is interested. And it is not 100% done. I would say more like 90% done. I still have to clean up some visual details and glue the top on permanantly.

Dominick in New Jersey
 

JonFo

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Congrats

Dominick,

Congrats!

It is always fun to design/build something and then enjoy it.

What midrange driver did you use?

Also, what's your take on the dispersions characteristics of this design?
MTM's typically have lobing issues when placed horizontally, and adding a couple more M's on the outer edges will have some effect as well. But everyone seems to be adopting this approach.
Are the outer driver (furthest left/right) power tapered?

Crossover slopes?

PS- can you post the images as post Attachments to this thread?

Imageshack gets my spyware program all excited and half the time refuses the let the pages through (for good reasons).
 

JonFo

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Dominick22 said:
...
Also, while I am sure it is obivous, what does MTM mean? Does that mean midrange-tweeter-midrange?

Dominick

Yes, that's Midrange-Tweeter-Midrange, also sometimes referred to as a D'Apollito config.

Here a thread discussing the pro's and cons of this for center channels:
http://forums.audioholics.com/forums/archive/index.php/t-4958.html

Also, a lot of lingo for speaker design and config can be picked up over at the DIYAudio forums.The members there are both knowledgeable and helpful.
 

Dominick22

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JonFo

I dont know how to do the images any other way. Sounds like you were able to see this pics though? I still have yet to learn how to build crossovers and how to determine the slope, etc. with the actual electronic parts. So I don't know the answers to those questions. The design comes in whole from partsexpress.com.

As for dispersion, sitting directly in front of the center, is pleasant although the tweeter can sometimes be a bit birght. I may be able to cure this with my amp settings...I am reluctant though since they are set for the Theater i!
The center is a tad bit bass shy (especially reproducing anything below a high tuned bass drum-ie anything below about 80-100hz) although the other speakers make up for it. I find it obvious switching from the Theater i...which I expected and would be upset about if this was not the case. The midrange is VERY clear. The midrange vocals (at moderate volume) give the Theater i a run for its money. But when volume is increased, the brightness of the center becomes harsh and the center seems a little like it is being stressed. This is the tweeter again. Quite honestly, the tweeter is the only area I would want to improve. I would use these midranges again. I think doing it over, I would have designed it with 4" (although I am not sure how this would change the vocals0 speakers throughout or added 5 1/4 woofers on the outer edgeS to improve bass response. One plus about the tweeter is that cymbols are produced exceptionally well.
Off axis listening does create the problem that your article link refers to. The bass semms to fade the farter left or right you are from the center and the tweeter takes over. It is an illusion that makes it seem as though the tweeter is getting brighter as you move left or right.

All in all, I have we have to remember that this project cost me about 250.00 start to finish. The theater i is about 3k. I really shouldnt compare the two. My point is that for 250.00, this center sounds better than anything you could buy at best buy or like stores. It is not Audiophile grade, but I would say that it is easily worth AT LEAST double what I spent. A great center for that second system in a bedroom or entertainment/play room.

Dominick
 

kach22i

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Dominick22 said:
It is not Audiophile grade, but I would say that it is easily worth AT LEAST double what I spent. A great center for that second system in a bedroom or entertainment/play room.

Dominick
I was just going to ask why you would need two center channels. ;)
 
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