Center channel designs for home theater

[4313B]

Hi for the New Year I would like to build a great center channel for my home theater system. The mid bass driver (pairs) options are 2218H, M203H, 2123H or a pair of 8” morel drivers, for midrange a single 2416H and maybe a single 2404 for the ultra high freq’s. The speaker configuration could be either a MTM or MT, depending or each merit's.

Ick! All those components are old and ragged. Soooo last century...
Just take $1,700, order the PC600 and you're done dude. It's soooo easy!
If you need a bit more for a perf screen installation go with the SK2-1000.
The new Project Array is really nice too.

[4313B]

IOW, eBay that obsolete stuff and make it someone else's problem, then get something that kicks hell out of that obsolete stuff.

Hope this helps!

[MJC]

slxrti, I just thought I would give you a heads up on a problem I had.
I built my HT and center around the L212 system, which has the 112A 8" mid-bass driver. I built a horizontal center using two of the 112A, one on each angled side baffle, with the 066 and 2105 mounted vertically on the center baffle. The resulting problem was way too much bass. A lot of center speakers use a smaller mid-bass driver than the matching L/R speakers, such as in the Performance Series HT system. Unfortunately JBL never made a 5 or 6 " driver that had the same sonic tone as the 112A.
So I scrapped the horizontal for a vertical 3 way, identical, to the main L212s, using only one 112A. But to get to fit below the rptv screen I didn't use a 13" tall base that the original L212s have. I made a 3" tall base that tilted back, so the 066 tweeter would be shooting to ear level, when seated.
The result is a perfect matched front end, which is what you want.

[slxrti]

Ick! All those components are old and ragged. Soooo last century...
Just take $1,700, order the PC600 and you're done dude. It's soooo easy!
If you need a bit more for a perf screen installation go with the SK2-1000.
The new Project Array is really nice too.

Just a little, I noticed a few other center channel's have the tweeter in a vertical alignment and the tweeter is of small size.

A 2404 is a option for the high end, since it is smaller, thus reducing from lopping.

At this point, the use of two large drivers spaced 12" apart does not seem
like a good ideal. If were to use the 2123, I would position them similar to the SK2-1000.

thanks for the input, Slxrti



slxrti.

[slxrti]

IOW, eBay that obsolete stuff and make it someone else's problem, then get something that kicks hell out of that obsolete stuff.

Hope this helps!

I could sell my 375's for $3000 and my new in the box 2235 for 700 and new 2123's for 400, then just purchase 10 to 20 pair of northridge.

Since I have LSPCAD design software, and my custom radio shack SPL meter (yet to be calibrated), I might as well use them.

btw, it is kind's fun to learn about the subject.

Slxrti

[andresohc]

I am using two 2122Hs, a 2425j/2307/2308 and a 2105H. A primary design concern for me is WAF, I attempte to place the woofers together as closely as poossible and still acommodate the 2308. I juggled them on a baffle and try and package as compactly as possible. I will intitially I guess Quad amp if you include the separate sub1500s on the side (my reciever has a mode to put center channel info though the sides subs) and will follow the Xover freqs of the 4345 (I dont remember off hand). I considered angling the 2122s away but decided to keep it as simple as possible initially and if I dont like it I will try again. I had all the stuff to build these cabs laying around and thought I would practice on my mdf speaker cabinet building with my intitial center channel. I have photos of the in progress boxes (just stuck on the veneer, didnt realize that contact cement would melt my paint ). Lobbing will be an issue and if I cant live with it I may try and modify the front baffle and or the crossover.

Hi, it seem that we have similar projects, If you don't mind me asking, which drivers are you using, what are your crossover freq.’s and the distance between each driver?

If I understand correctly the main cause of loping is the over lapping response between driver’s two drivers. Since two drivers share the same pass band loping will be inherent in this topology, Is this the case?

Can I assume the crossover will minimize the problem, but not eliminate it?


thanks slxrti

[Zilch]

Center channels are Glorious Mono. Since stereo came along the idea of making a single speaker is strange today.

Center channels are a WAY fun DIY project. Just finding a configuration that physically mates with the video setup is a challenge.

In this one for Hamilton, I just grabbed the classic D'Appolito MTM alignment and used BB6P for the box calculations. It makes a shallow-profile (6") box that can be wall mounted, or in the installation shown, mounted under-screen with a bit of upward tilt toward the seating area:

http://audioheritage.org/vbulletin/s...ead.php?t=7004

In retrospect, since we adjusted the crossover frequency a bit, studying the actual performance might reveal an optimized woofer spacing.

Hamilton's mains are 4430's, so the 2342 biradial seemed a good match. He went on to construct two-way surrounds using them and LE14A's, which also worked out:

http://manuals.harman.com/JBL/HOM/Te...200t3%20ts.pdf

I've done some subsequent work with various drivers on 2342's, and concluded that 2416H-1 sounds better than the cheaper 2418H-1. Working with 2426H on them now, what Hamilton used, I may have some recommendations for crossover tweaks soon.

I could sell my 375's for $3000 and my new in the box 2235 for 700 and new 2123's for 400, then just purchase 10 to 20 pair of northridge.

Since I have LSPCAD design software, and my custom radio shack SPL meter (yet to be calibrated), I might as well use them.

btw, it is kind's fun to learn about the subject.

We've already had several suggestions here in the new DIY forum that we should just sell this old stuff and buy professionally-designed systems. I kinda like Toddalin's response, if I may exercise license to paraphrase:

"I KNOW there's better systems out there to buy. I have what I have, tho, and I just want to make it work its best...."

Somehow, buyin' plastic models was never as satisfying as building 'em from scratch....

Andre gets it, apparently. Is there anywhere but here to purchase that smile?

[4313B]

btw, it is kind's fun to learn about the subject.

I suppose...

You guys definitely have a fascination with the old stuff. I did too, and not that long ago either.

[andresohc]

Its an opportunity to practice my cabinet making skills as well. I got to reveneer one end this afternoon, 1/32 short on one cut. Overlapped and cleaned up with a router this time. The smile is from my boy. He loves to hang out in my shop (when its not dangerous) and help when possible. For me the point is taking stuff others have passed over and celebrate what it can do when properly nurtured. Just like restoring old Honda MCs for me. Others think they are junk but when I was 14 they rocked the world and changed the face of motorcycling. I couldnt afford Hondas then now I implicitly understand the design of a 75 CB400F by dissassembling it to its smallest components and rebuilding it. Similar with my 4345 project. I would build it full sized and like the original if I didnt have a 1000 square foot house. Instead I am arrogantly trying to combine old and new technology (use what I have and make it work) I realize I am likely to fall flat on my face but at least I am up and moving and doing something. My goal this year is to spend at least as much time up and doing things each day as on the computer.

[Hamilton]

You guys definitely have a fascination with the old stuff.

Sometimes it's not by choice...old house painters don't make a whole lot of money.

[slxrti]

Center channels are a WAY fun DIY project. Just finding a configuration that physically mates with the video setup is a challenge.

In this one for Hamilton, I just grabbed the classic D'Appolito MTM alignment and used BB6P for the box calculations. It makes a shallow-profile (6") box that can be wall mounted, or in the installation shown, mounted under-screen with a bit of upward tilt toward the seating area:

http://audioheritage.org/vbulletin/s...ead.php?t=7004

In retrospect, since we adjusted the crossover frequency a bit, studying the actual performance might reveal an optimized woofer spacing.

Hamilton's mains are 4430's, so the 2342 biradial seemed a good match. He went on to construct two-way surrounds using them and LE14A's, which also worked out:

http://manuals.harman.com/JBL/HOM/Te...200t3%20ts.pdf

I've done some subsequent work with various drivers on 2342's, and concluded that 2416H-1 sounds better than the cheaper 2418H-1. Working with 2426H on them now, what Hamilton used, I may have some recommendations for crossover tweaks soon.

We've already had several suggestions here in the new DIY forum that we should just sell this old stuff and buy professionally-designed systems. I kinda like Toddalin's response, if I may exercise license to paraphrase:

"I KNOW there's better systems out there to buy. I have what I have, tho, and I just want to make it work its best...."

Somehow, buyin' plastic models was never as satisfying as building 'em from scratch....

Andre gets it, apparently. Is there anywhere but here to purchase that smile?

Hi Zilch, I would be very interested in your findings regarding the classic D'Appolito MTM alignment, before I let the wood chips fly.

If Giskard was word's of wisdom, I'm all ears .

Slxrti

[4313B]

Andre gets it, apparently. Is there anywhere but here to purchase that smile?

Oh I get it Zilch. You're just about where I was maybe 25 years ago.

If Giskard was word's of wisdom, I'm all ears .

I don't know what you mean.

Sometimes it's not by choice...old house painters don't make a whole lot of money.

Yeah I hear you. I've posted quite a few times how irritated I get that people think all the old stuff is worth so much because it isn't and I'd like to see you all be able to pick it up for what it is really worth and enjoy playing around with it. It really shouldn't cost you a whole lot to pick up an old pair of L300's or what not and give them a spin, etc.

[Ian Mackenzie]

Oh I get it Zilch. You're just about where I was maybe 25 years ago.

The context here might better be phased one years experience 25 times over....by 2031

[4313B]

The context here might better be phased one years experience 25 times over....

I don't get it.

[Zilch]

I don't know what you mean.

I used horizontal MTM woofer spacing per D'Appolito: woofs are centered one wavelength at crossover frequency each side of the tweeter centerline, in this case a 2342 horn.

I believe Slxrti is inquiring if you have any thoughts on the suitability of this alignment for DIY center channel construction....