You have my sympathy. Centers are an absolute nightmare, in terms of design, aesthetics, installation and function.
Honestly I don't think there is a commercial sub that satisfies all of the above.
First challenge:- Designing a speaker with outstanding high quality, intelligible speech through out the room, and having enough spl. to match or exceed the left and right speakers. It must also be an exemplary speaker with uniform FR on and off axis.
Aesthetics: - It must be visually appealing as it is always in sight.
Installation challenge. Making something not awkward, and with safe installation. With large screens the speaker gets to low, or the screen too high making neat above screen installation the preferred option, unless you can use the acoustically transparent screen option.
So horizontal MTM fails due to very poor dispersion off axis, and enhanced floor reflections due excess dispersion in the vertical plane which reduces speech intelligibility.
The speaker was be as coherent as possible to have good speech clarity.
Options are for three ways with vertical tweeter mid. The problem this does lead to a speaker that is too tall to be ideal if placed above or over a TV. This makes the poor horizontal MTM approach the more prevalent design, in addition to cost.
This is where function and aesthetics get into harmony. The optimal solution I am certain is a coaxial design or a good full ranger. I don't know of a good driver that is full range with enough power handling for most applications. However for smaller room, especially apartments they are around, and I did it successfully at our the condo we had.
For a neat situation an in wall, or better still ,a through wall design is optimal. I have done both. It is the center that with what is available currently ONLY the DIY home builder can satisfy the criteria I have set out above. If you are able building your center will allow you to get things really correct.
The optimal solution is a coaxial center.
My final solution, was to go for an in wall design. This is preferable to in wall which is second best. The reason is that it significantly reduces the troublesome flat wall large baffle problems
I built my design around this driver. This driver is ideal for TL, but models well in ported and sealed solutions.
This is a potent driver that can handle 200 watts continuous power.
A SEAS crossover has subsequently become available.
Now I did have a tweeter fail, and had to repair a driver, so I redesigned the high pass crossover to third order. I have had no trouble now in years of use, and I have powered it hard.
Now I used two of these drivers, as with through wall baffle step compensation is required. Mine is active and variable to optimize it, but it could easily be passive. However the bi-amp design significantly increases spl.
The other issue, is that with coaxial speaker designs tend to have cancelling reflections from the cone. I was able to design and build a passive equalizing network utilizing the tweeter in the BSC fill driver. I would be happy to share the design with any of you. So the design is an unusual 2.5.5 way.
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In summary, I am yet to hear a better center speaker than this one, especially in terms of clear, natural speech, excellent music quality and even coverage of the listening area of the room.
I will certainly be happy to assist any member that want to build a center along these lines. I think this has been the most difficult design I have undertaken. Although the right and left are more complex their design was easier and they were dead right from the start. This center was more problematic in its development. I well understand why many centers fall well short of the mark, on multiple counts. Center speakers are just very difficult to design properly.
