[aceinc]

I am considering building a new center channel speaker for my HT system. Traditional center channels are quite often sideways MTM designs. When done poorly the woofers will cancel each other out when sitting off axis at various frequencies. I would like to avoid this.

My thought on how to accomplish this is to use a narrow tweeter which will crossover at a low frequency, allowing me to put the woofers close together. By way of example I was thinking of the following design criteria

Two 8" woofers with their centers ~10"-11" apart with a 24db crossover centered at 1khz. The woofers are ~93db efficient - 2.83v @ 4 ohms. The tweeter is ~ 94 DB efficient @ 8 ohms.

My thoughts are since the center of crossover is 1khz with the woofers' centers being within ~10.5" and this wavelength is ~1.25khz, I should avoid most if not all inter woofer off axis cancellation.

Is this true?

Or am I missing the point?

[Tyson]

Why not mount the tweeter on top of the box and then that would let you mount the midrange drivers literally right next to each other.   Something like this:

[aceinc]

I was shooting for a 2 way design.

It would be interesting to see a horizontal off axis plot of the speaker you pictured.

Part of my impetus to create a new center channel is this video;

https://www.youtube.com/watch?v=GZrdsxrcpBw

[WGH]

Have you designed speakers and crossovers?

The speaker you describe matches the GR Research X-CS Center Speaker. Danny at GR Research has been designing speakers for a long time. He would answer any questions about frequency cancellation or other stuff mentioned in the video as regards to the X-CS. That would be my starting point for a DIY speaker.
https://gr-research.com/product/x-cs-encore/

Plenty of info in the GR Research Circle - ask questions here
https://www.audiocircle.com/index.php?board=16

X-CS Encore - Sensitivity is 90db, sealed box

[aceinc]

Well "designed," might be too strong a word, but I have built speakers and a few have not been from other's plans or kits. They have generally turned out well. The center channel I am currently using I "created" about 15 years ago and works reasonably well. I believe with the knowledge I have gained in the intervening years I believe I could do better.

I was originally going to post this question in Danny's circle, but my design ideas are based on PE parts, not his and I don't want to ask for help from someone when not buying their stuff.

[Tyson]

If doing a 2 way, this a driver layout like this would be best:

[jtwrace]

I am considering building a new center channel speaker for my HT system. Traditional center channels are quite often sideways MTM designs. When done poorly the woofers will cancel each other out when sitting off axis at various frequencies. I would like to avoid this.

My thought on how to accomplish this is to use a narrow tweeter which will crossover at a low frequency, allowing me to put the woofers close together. By way of example I was thinking of the following design criteria

Two 8" woofers with their centers ~10"-11" apart with a 24db crossover centered at 1khz. The woofers are ~93db efficient - 2.83v @ 4 ohms. The tweeter is ~ 94 DB efficient @ 8 ohms.

My thoughts are since the center of crossover is 1khz with the woofers' centers being within ~10.5" and this wavelength is ~1.25khz, I should avoid most if not all inter woofer off axis cancellation.

Is this true?

Or am I missing the point?

Watch this

[WGH]

I'm on my third center channel speaker.
The first was a JBL 2500, I found a pair at a yard sale super cheap. The experiment was educational and didn't sound that good.

The second was RAW HT2C with the excellent Aurum Cantus ribbon tweeter. The specs looked fantastic:
- 2 x CSS WR125ST 4.5" matched woofers with cast aluminum frames, copper phase plugs and XBL² motors
- 1 x Aurum Cantus G2si ribbon tweeter
- High quality parallel crossover network
- Solen air core inductors
- Solen polypropylene capacitors
- Silver wiring
- Well constructed enclosure lined with 1" Ice Absorption sound damping material
In reality the speaker wasn't that clear and dialog was still hard to understand plus the rear ports gave an unnatural resonance to male voices.




The third is a Salk HT2C center channel and it is perfect. The speaker is a sealed design and the drivers are the same as in my L & R speakers. The Seas W18 and RAAL tweeter are fast and clear so the center channel intelligibility is extremely high, my guests and l have no problem understanding dialogue.




The sound in my home theater only became seamless when all three speakers, L, C, & R, were the same. When the soundtrack and dialog can move between speakers without a change in timbre it results in a more immersive viewing experience. The center channel is the most important speaker and should be equal to if not better than your L & R speakers.

What are your L & R speakers? Can you use the same drivers for the center channel speaker? It is important to keep the voicing the same to end up with a successful build.

[aceinc]

It has not been my experience regarding the center & fronts being the same. The dialog from the existing center channel is good for me, but occasionally my wife will ask what someone said. My center is very dissimilar from my fronts which at present are Magnepan 2.7 QRs.

I will not be trying to match my Maggies, but I am contemplating building an open baffle center channel.

[aceinc]

Watch this

I did and posted the same link above.

[aceinc]

If doing a 2 way, this a driver layout like this would be best:

This does deal with the problem of cancellation, as long as the crossover point is below the wavelength distance between the center of the two woofers (which it probably is).

This assumes I know what I am talking about which is what I am hoping to get confirmation of.

[Tyson]

This does deal with the problem of cancellation, as long as the crossover point is below the wavelength distance between the center of the two woofers (which it probably is).

This assumes I know what I am talking about which is what I am hoping to get confirmation of.

Correct.