Budget MTM Towers

S7910

This is one of the designs I plan to bring to DDIY this year. I'm sure some of you will recognize them from when they were at DIY Iowa a couple years ago.

Drivers: Peerless SDS-160F25PR01 on woofer duty and the GRS 1TM-4 tweeter. The woofers were selected because they modeled well in a reasonably sized cabinet and they were (and still are) attractively priced. The GRS tweeter was selected because it paired well with the woofer and fit the budget requirements.

Cabinet: After measuring the woofers and modeling them in Unibox, a cabinet volume of 50L was arrived at. The woofers dictated the baffle width, as I used a method that Pete S. had posted on PETT awhile back where the baffle went from truncated edge to truncated edge on the woofers. This set the baffle width at 6.5", and I arrived at a baffle height of 46.5". The external dimensions of the cabinet then fell into place at 48" H x 8" W x 12" D. The cabinet walls behind the drivers are lined with eggcrate foam, but other damping materials could be substituted if desired. Fb/F3 comes out to 40Hz for both. The port is front mounted and centered 6.5" from the bottom of the cabinet. The woofers are centered on the baffle and are 5.5" and 15.75 from the top of the cabinet. The tweeter is centered on the baffle and is 10.5" from the top of the cabinet.

Crossover: This was done by ear just for fun. That and I like tinkering with things so the 'trial and error method' is the most enjoyable part of the process for me.

The woofers are wired in parallel with a first order electrical filter of .55mH.
The tweeter is wired in reverse polarity with a second order electrical filter of 3.3uF and 1.0mH.

BOM:


Unibox info:





The speakers themselves:



I'll let others who have heard them comment on how they sound.
Thanks for looking.

rjj45

Very nice!
Good Unibox model, plenty marginal xmax left over

S7910

rjj45 said:

Very nice!
Good Unibox model, plenty marginal xmax left over

Thanks!

That kind of headroom is always a good thing. I have yet to bottom out the woofers - and that's not for lack of trying.

4thtry

Cool project.  Look forward to hearing these.  

S7910

Couple of post-IOWA updates on these.

I've named them "Nexus". Based on how the project progressed from concept to finished speaker it fits well.

I had originally intended to veneer them, but @JasonP suggested staining them instead after I get them sanded. The more I think about it the more I like the idea.

Next stop InDIYana?

rjj45

S7910 said:

Couple of post-IOWA updates on these.

I've named them "Nexus". Based on how the project progressed from concept to finished speaker it fits well.

I had originally intended to veneer them, but @JasonP suggested staining them instead after I get them sanded. The more I think about it the more I like the idea.

Next stop InDIYana?

I used some no-name mahogany stain on a BB voxel subwoofer - came out pretty good - if I was serious about the looks, I'd use some pre-stain conditioner for a more even look. I used a couple of base coats of amber shellac on a Quarks build and really love that look. Here's the clear coat and the amber pair. 

S7910

Those are gorgeous. I like how the amber brings out the grain.

S7910

Decided to go with two coats of Black Walnut Watco Danish Oil on these. I really like the way they are turning out, and the grain of the baffles is making a really convincing argument for getting non-veneered plywood. This shows something of a before and after. About all I have left to do at this point is painting the ports.