Design Critique

[ocho]

Hi, I'm currently in the process of designing a MTM speaker, and was wondering if I could get some advice on design. The design is roughly based upon the 1cuft speaker box available at parts-express (I'll be building the box myself however), and some MTM designs on this site. What I'm mostly concerned about is whether or not I really need the sub-section just for the tweeter ( my reason for doing this is to ensure the backwave of the woofers dont affect the tweeter, but I'm not sure if this is a big deal for MTMs ). Attached are some renders I've made.

Thanks for your help!

NOTE: the 3rd render is just a cut out of the inner structure stuff so you can tell what it looks like better.

[bluewizard]

If the back of the tweeter is already sealed then you don't need a separate chamber for it. Though, it certainly can't hurt to have it in a separate chamber.

However, I'm wondering about the clearance between the port's inner opening and the back of the tweeter chamber. It looks OK, but you don't want those too close together.

Also, flared ports, inside and out, are to your advantage. You can actually used flared tubes or you can simply route the edges round.

The difficult part will be to accurately design the crossovers. Though you indicate you are copying existing designs, so that should simplify that aspect.

Just a few thoughts, I'm sure others who are more knowledgable will have more details.

Steve/bluewizard

[ocho]

Wizard, thanks for notes. I'll have to check the tweeter and the clearance. The knowledge about flared ports is also nice.

As for the x-overs, I'll actually be designing those too, lol. I'm in a speaker design class, and my partner and I are gonna design them. We're both electrical engineers though (we'll I'm actually a computer engineer, but I still know a good bit about EE ), so hopefully we'll do ok in that respect too.

[alias2]

EE's can get crossovers hopelessly wrong because they are sure that they of
all people ought to know what they are doing, a little knowledge is dangerous.

Beware of oversimplification, http://www.rjbaudio.com/Audiofiles/FRDtools.html

/alias2. (EEE)

[fjhuerta]

EE's can get crossovers hopelessly wrong because they are sure that they of
all people ought to know what they are doing

+1

[fbov]

+1 on the port clearance concern, but there's another reason to box-in the tweeter - strength.

Close driver spacing in an MTM reduces the strength of the baffle near the center-to-center lines between drivers. A tweeter enclosure reinforces the baffle at these points, reducing baffle resonances. Once enclosed, it's also easy to add a brace, as you've shown. However, your full-height cavity takes a lot of volume out of the box. I use the woofer cut-out disks to cover the tweeter, with the added advantage of increasing port clearance.
Frank

[Curt C]

Nicely done! I like how the port tube serves the additional function of tying the vertical brace (and via the stringers, the front baffle and sides) to the rear baffle. Depending on the tweeter chosen you can open up the tweeter ‘enclosure’, as it generally is not necessary.

Ideally, the port should be flared on both ends, and the internal port terminus should be at least one port diameter from the adjacent wall (Another reason to lose the tweeter enclosure.) The vertical brace doesn’t need to be positioned centered between the front and rear baffles, so it can accommodate modest changes in port length to accommodate the tuning chosen.

C