Need Help Designing Smaller Version of Apollo-7 MTM Center Channel

I'd like to upgrade my center channel for my home TV/Theater setup.

I have about 8" of space just below the TV for the center channel (it's a built-in cabinet, so I can't simply move the TV up higher).

The Apollo-7 MTM by DIYSoundGroup looks awesome , and I've built a few kits from them already. But it's a 10" tall speaker box. So I was thinking I could create a very similar setup, but with the Anarchy 5.5" speakers.

What I'd love to know is:
1. Does this seem like a good solution?
2. How do I figure out the box size?
3. Could I use the same crossover as provided for the 7" drivers?

Thanks in advance! I've been having a blast getting into DIY speaker building, but designing my own box is definitely going to be a first.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
I'd like to upgrade my center channel....
....2. How do I figure out the box size?........

So this is not your earthquake-shake speaker? Mostly to put center action in the center of the sound stage? Bass response (box size) is not critical.

Considering the total lack of specs here, and the not-large change of size, both from the same designer(?), _I_ would just scale all dimensions by driver size.

5.5/7 = 0.786

9.5" W x 23.5" H x 13" D * 0.78 = 7.46 x 18.47 x 10.2 inch

(Ideally we would get the _inside_ dimensions and scale them. Or get boards 0.78 as thick, say 3/4 to 5/8, which would come real close. But large change of box volume makes small change of bass response, and this is not your shaker-speaker, so you don't need micrometer accuracy.)

If you have exactly 8.0" of height, I might consider fudging 7.46 x 10.2 to say 8.0 x 9.5. Avoids cavities around the speaker, and sticks-out a half-inch less.

And then I would look at available pre-cut shelf boards and take the best fit with the least ripping.
 

cobrajones

Member
2019-10-23 5:20 am
Thanks so much!

So this is not your earthquake-shake speaker? Mostly to put center action in the center of the sound stage? Bass response (box size) is not critical.
Correct. I have subs and surround speakers. This will just be center.

Do you think it would be worth trying to get the specs? Or is scaling going to sound ideal? And if I use the same tweeter, will that affect the size considerations of the box? Crossover?
 

Attachments

  • Anarchy5.5in.JPG
    Anarchy5.5in.JPG
    408.9 KB · Views: 50
So I was thinking I could create a very similar setup, but with the Anarchy 5.5" speakers.

What I'd love to know is:
1. Does this seem like a good solution?
2. How do I figure out the box size?
3. Could I use the same crossover as provided for the 7" drivers?
It is good solution :) if you have measurement equipment, know how to measure TS and SPL and have appropriate modeling software

Box size - need to know TS of woofers. Measure, enter in design software (BoxSim by example) get the results
Current crossover will not be usable do to the different baffle size and different drivers. And it is not possible to design without extensive measurement effort. While designing crossovers you will be stuck in the loop of measure --> put data in model --> adjust --> measure again, for some time. You will need .frd and .zma files, preferably with phase data, for all drivers in order to do it correctly. That will require microphone (+ some trinkets soldered on the spot) and appropriate software for crossover design (I use lspCAD).

So if you not willing to go to trouble of measuring and designing your own center speaker project from scratch, just find something suitable and recreate it one-to-one
 
Last edited:
If you have dats you can measure the parameters.
Bjorno has measured and run a very comprehensive analysis of the driver, on the second page of the liked thread.
That is enough for box calculations but not for the crossover design. Given that this is center speaker bass reproduction from 90Hz to 120Hz is quite adequate a would go with closed box enclosure there other reason not to use any ported enclosures for center but that aside. Few liters (8-16) box will suffice here, but the issue with required measurements for new crossover still remain open