# Center Channel upgrade.



## F1 fan (Jul 6, 2006)

Im just in the planning stages and it may qualify as overkill :bigsmile:but I have decided to go all the way and make my center channel into a full a 4 way (active)system like the main left and rights.I am very pleased with the performance of my recently completed MTM center and it is quite capable dynamically, I just wanted to hopefully take performance to the next level.Instead of building a totally new(and very large) enclosure I am going with an unusual approach.

As shown in the pics there are two storage compartments on either side and underneath the plasma.These compartments happen to be exactly big enough to fit an MDF box of the correct volume for the woofers I intend to use. Ideally I wanted to use the same 8" SEAS woofers(see link to my HT for system details) as in the mains but they are no longer available.However I can get the similar SEAS CA21 REX which is nearly identical spec wise but it has a paper cone while the others are polypropylene.

I will use two (one in each compartment) to improve sensitivity and dramatically increase headroom.The enclosures will be sealed and have the same volume thus the same bass extension as the mains which means an f3 in the 65hz region.Like the mains they will be summed and combined with the common bass module that covers the 65hz down to 35 hz.

The woofer to midrange crossover in the mains occurs at 300hz with 24db Linkwitz Riley slopes,but the wider separation between the MTM and new woofers will require that I cross them over lower possibly at 200hz or so,I still have to work out the details.The fact that it will be an active crossover will allow for quick changes in crossover frequency.

The pics also show the main speakers and the big pine coffin in the corner is the bass module.

http://www.hometheatershack.com/forums/home-theater-equipment/1830-my-ht.html


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## Sonnie (Apr 11, 2006)

Sounds like a great idea... I could do that with my RPTV if I had a system in my great room.


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## F1 fan (Jul 6, 2006)

Sonnie said:


> Sounds like a great idea...


Well Im always on the lookout for places to stick more drivers and this looked do able.My biggest challenge will be making good looking grille covers because as you can see in the pics I don't have any expierience building them as I prefer my drivers naked.


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## JCD (Apr 20, 2006)

I've got some concerns about the large space between the MTM and the woofers.. the concern being the loss of a "point source" for all the sound. I'm not saying it can't be done here, just that I haven't seen this type of configuration and this was the issue I immediately thought of.

JCD


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## F1 fan (Jul 6, 2006)

JCD said:


> I've got some concerns about the large space between the MTM and the woofers. the concern being the loss of a "point source" for all the sound.


 Agreed it is a concern.The spacing between the center of mid woofers in the MTM and the woofers will be approximately 45".This pretty much rules out the use of the same 300hz crossover as I used in the mains. Eventhough 45" is equal to one wavelength at 300hz (which is right at the recommended limit according to Dickason in the LSDC)I prefer a margin of error so will first try to crossover at 200hz(wavelength =68").If that turns out to be a sonic disaster then I can lower the crossover even further.


> not saying it can't be done here, just that I haven't seen this type of configuration and this was the issue I immediately thought of


Yah I have not seen this configuration either so its hard to say how it will workout until I give it a try.At least it gives me an excuse to buy more drivers.:bigsmile:
Thanks for your input.


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## ktaillon (Apr 3, 2007)

What brand are you using for a Electronic crossover? I use electronic crossovers for my two channel setup, its works out really well and I can't see myself going back to passive crossovers. Are you just planning to do this on the front three only?

I'm very interested..... ummm


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## F1 fan (Jul 6, 2006)

ktaillon said:


> What brand are you using for a Electronic crossover?


Here is a listing of what Im using.http://www.hometheatershack.com/forums/home-theater-equipment/1830-my-ht.html


> I use electronic crossovers for my two channel setup


Cool:T what are you using in your setup?


> I can't see myself going back to passive crossovers.


Likewise, Im sold on the many performance advantages of the active approach.


> Are you just planning to do this on the front three only?


Yes,my front three are already completely active , Im just extending the center channel from a 3 way to a 4 way.


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