DIY Center Channel

[augmont]

Hi - Newbie and New to the forum

I happen to have a 3rd floor standing speaker that's identical to my fronts. Is it possible to build a center channel speaker using all the components from the 3rd speaker to match the mains?

My logic tells me that if i build the box the same size/volume as the mains but reposition the speakers so they are symmetrical horizontal it would work, or close to it.

[Hdale85]

You would need to redesign the crossover as the baffle will change and the configuration will change.

[joecarrow]

There's another problem- depending on the crossover frequency and driver size and spacing, the sound can be kind of off if you're listening down by the floor or up near the ceiling- that is to say, listening off axis in the vertical plane. If you basically turn the speaker sideways, or lay it out horizontally, then it can have a bad effect on listening positions spaced out horizontally. The effect is that the center couch cushion might sound alright, where the left and right ones sound different in a bad way.

If you post some more about the main speakers then we might be able to give some more informed advice about what's possible.

I second what Dougie says- it would involve redesigning the crossover to get good sound. This might prove to be a major challenge, depending on the drivers and your abilities.

[cjd]

2-way or 3-way? What size drivers?

I assume there's a reason you need to go with the shorter wider construction compromise?

[augmont]

There's another problem- depending on the crossover frequency and driver size and spacing, the sound can be kind of off if you're listening down by the floor or up near the ceiling- that is to say, listening off axis in the vertical plane. If you basically turn the speaker sideways, or lay it out horizontally, then it can have a bad effect on listening positions spaced out horizontally. The effect is that the center couch cushion might sound alright, where the left and right ones sound different in a bad way.

If you post some more about the main speakers then we might be able to give some more informed advice about what's possible.

I second what Dougie says- it would involve redesigning the crossover to get good sound. This might prove to be a major challenge, depending on the drivers and your abilities.

My mains are Infinity Primus 360's and here are the specs.

Frequency Range: 38Hz – 20,000Hz (±3dB)
Recommended Amplifier Power Range: 10 – 200 watts
Sensitivity: 93dB (2.83V @ 1 meter)
Nominal Impedance: 8Ω
Crossover Frequency: 350Hz, 3300Hz; 24dB/octave
Low-Frequency Driver: Dual 6-1/2" (165mm) MMD,™
magnetically shielded magnetically shielded magnetically shielded
Mid-Frequency Driver: 4" (100mm) MMD
magnetically shielded
High-Frequency Driver: 3/4" (19mm) MMD,
magnetically shielded magnetically shielded magnetically shielded
Dimensions (H x W x D): 39" x 8-1/4" x 13"
Weight: ) 48.5 lb (22kg)


Thanks guys

[augmont]

2-way or 3-way? What size drivers?

I assume there's a reason you need to go with the shorter wider construction compromise?

Here's my current setup. I currently have a center channel however with recent upgrades to my front, the center now sounds too small. The photo doesn't have my new mains but there are on the outside of the bookcases.

[joecarrow]

Nice TV!

Ok, just knowing those crossover frequencies helps. This is just my opinion, but I think the frequencies used say that the crossover to the woofers is no problem, but the crossover to the tweeter is just a tad high. The wavelength at 3300 hz is just about 4 inches, so the midrange is starting to beam at the crossover point. They could have done better with that, but it probably provides reasonably good sound for the minimum manufacturing cost.

In my opinion, if you kept the speaker layout the same and merely turned it on its side, it wouldn't be much worse of a center than it is as a main. It would help less than you'd think to move that other 6.5" woofer to the other side to make it look more symmetrical. I say go ahead and turn the thing on its side, put it where you want it, and see if the sound is acceptable as you sit in the different parts of your room where you will be listening.

Anything much more than this is going to involve fairly complex crossover design that won't be possible without detailed measurements with specialized equipment. You'd need a measurement microphone, a pre-amp, and the equipment to do impedance and T/S tests. By the time you pay for all that and get a new passive crossover built, it would be cheaper just to build one of the Mission Accomplished designs, or buy a commercially available center.

By far you would get the best performance from one of the Mission Accomplished designs. Good luck in whatever you decide to do.

[cjd]

So, the simple answer is yes, you can to a WTMW arrangement and it will work. Keep the tweeter above the mid, both centered on your box. Flank with the mid-woofers. Pretty standard WTMW.

You do NOT want to make the mid-tweeter arrangement horizontal - it needs to remain vertical.

It will be a compromise, but it may not be any more compromise than already exists in the crossover. Very hard to say. The compromise is more than most people around here would choose to accept, but we tend to be a perfectionist lot. Being a 3-way with 4 drivers kind-of makes this simpler and less problematic than if it were a 2-way. But if it sounds bad, it's a lot worse.

C

[augmont]

So, the simple answer is yes, you can to a WTMW arrangement and it will work. Keep the tweeter above the mid, both centered on your box. Flank with the mid-woofers. Pretty standard WTMW.

You do NOT want to make the mid-tweeter arrangement horizontal - it needs to remain vertical.

It will be a compromise, but it may not be any more compromise than already exists in the crossover. Very hard to say. The compromise is more than most people around here would choose to accept, but we tend to be a perfectionist lot. Being a 3-way with 4 drivers kind-of makes this simpler and less problematic than if it were a 2-way. But if it sounds bad, it's a lot worse.

C

Thanks for everyone's input. Here's a few more question.

1.) In making the cabinet, I assume I need to also reuse the port and not make a sealed center?

2.) I assume the volume of the cabinet has to be the same?

3.) If you notice from my picture I currently have a smaller center that's under the TV, then I have AV equipment that's under the center. Could I make a cube center that occupies both space and take up the entire center? Or is it better to have wider spacing of the W's by making it enlongated?

[Hdale85]

You could make it sealed I believe. But you want the baffle to at least be the same width.

[cjd]

Eh, putting it anywhere near the TV totally screws with any baffle step or diffraction accomodations that might (or might not) exist in the crossover. THAT is probably a bigger potential problem than the other weirdness that will likely develop from changing the driver arrangement.

Understand, it may not really be everything you hope it can be, but it could do surprisingly well. Some crossovers I've done (including my MTM) are intentionally pretty darned flexible to allow placement whatever which way. And some can't come close to managing this and things just go whack.

Sealed vs ported only affects low frequency extension. If you keep the port, keep the internal box volume pretty much exactly the same. If you don't think you can do this, go sealed. With a sub and a traditional receiver (and your mains/center set to "SMALL"), it'll probably make zero difference. In fact, sealed could be an improvement.

C

[augmont]

Eh, putting it anywhere near the TV totally screws with any baffle step or diffraction accomodations that might (or might not) exist in the crossover. THAT is probably a bigger potential problem than the other weirdness that will likely develop from changing the driver arrangement.

Understand, it may not really be everything you hope it can be, but it could do surprisingly well. Some crossovers I've done (including my MTM) are intentionally pretty darned flexible to allow placement whatever which way. And some can't come close to managing this and things just go whack.

Sealed vs ported only affects low frequency extension. If you keep the port, keep the internal box volume pretty much exactly the same. If you don't think you can do this, go sealed. With a sub and a traditional receiver (and your mains/center set to "SMALL"), it'll probably make zero difference. In fact, sealed could be an improvement.

C

Thanks CJD.

I checked out the inside of the speaker. The interior is a open with two supporting brackets spaced evenly (from what I could tell). the mid had a plastic cylinder encloser behind it. The T and W were open to the cabinet.

The current speaker arrange from top to bottom is MTWWP (P=Port).

If I seal the cabinet, do I still need to maintain the interior volume?

[Hdale85]

No it should actually be somewhat smaller if its sealed.

[mlstrass]

Just looked at one of your speakers and you'll have to build a new cabinet. A lot of Klipsch guys just make a new baffle.

I'd make it the same enclosure size, port out front or rear, and mount tweeter above the mid in the center as suggested.

Box will have to be taller (wider than original) to make that fit, but should work fine. Unless you have a super discerning listening ear....

[augmont]

Just looked at one of your speakers and you'll have to build a new cabinet. A lot of Klipsch guys just make a new baffle.

I'd make it the same enclosure size, port out front or rear, and mount tweeter above the mid in the center as suggested.

Box will have to be taller (wider than original) to make that fit, but should work fine. Unless you have a super discerning listening ear....

The mains have the mid above the tweeter. Should I still have the tweeter above the mid as it's been said or should I follow the mains and have the mid above the tweeter?

[cjd]

Oh, that's less critical, but it depends if you're going to place it over or under the big glass box. If under, tweeter on top. If over, tweeter under.

The biggest issue is keeping them aligned verticaly.

[augmont]

Almost Done...

Oh, that's less critical, but it depends if you're going to place it over or under the big glass box. If under, tweeter on top. If over, tweeter under.

The biggest issue is keeping them aligned verticaly.

First of all, thanks to everyone for their input and advice. This is one of the most friendly, helpful forums I've been involved and or have read.

Second, I've almost finished my new center cube speaker. The only thing left is to build the grill.

Third, the project itself rather easy with a few gliches. I look foward to building a sub next. I will definitely use a pre-designed plan. I'd like to use a TC's speaker like the one in SVS's PS10-ISD. My budget will be around $300 dollars. Perhaps there are some recommendations from you all!!

Fourth, I'm quite pleased with the over all sound. The most important factor to me was that it sound better than my current center channal speaker and it did.

Here are some pics. Thanks Again.

[Hdale85]

Wonder if that little lip right above the tweeter is going to cause issues

[ThomasW]

Might want to relocate the damping material obstructing the port.

[augmont]

Might want to relocate the damping material obstructing the port.

Finished the grill. I was so excited on finishing the grill and focused on apply the cloth wrinkle free that I forgot to spray the frame black. Luckily it only shows up when you take a picture. You can't tell in person.