4eleven

4 MCM 55-1860 6.5" woofers
1 Vifa M13MI-08-08 Alnico midrange
1 Vifa XT25-30-04 tweeter

Open-back midrange enclosure
Mahogany Veneer
90dB sensitivity
100 lbs each

Construction Details:


The front baffle was made from a .75" layer of Maple ply and a .75" layer of MDF.  "Back Chamfer" was added for each driver cutout.

External dimensions: 43" x 9.5" x 14"

The four woofers share the same enclosure.

Extra bracing.

Open-back midrange tunnel.  The enclosure is about 14" deep; the mid crosses to the woofers at about 250Hz; 1/4 wavelength at 250Hz is 14".   Seems to work well.  I don't know if it's the open-back nature of this enclosure of the sonic characteristics of the Vifa Alnico mid driver, but midrange on the 4eleven is very natural, open, and dynamic.

I like to cut my front rear baffles a bit oversized then flush trim with the router.  It's kind of a pain but the results make it look as though I know how to build boxes.

Instead of a small roundover I went for a big bevel on the front baffle.  I cut the front baffle at 30 degrees to the face rather than 45 deg.  This 30, 60, 90 triangle made it easy for me to do a bit of trigonometry and figure out where a cut on the side of the box would emerge on the front of the baffle.  I feel that the 30 deg bevel is a better choice than the 45 deg because there is a more gradual drop in pressure as the wave passes to the edge of the enclosure thus ensuring that bla, bla, bla.  Ok, I think it looks cool.

Instead of building a large alignment fixture to slide the entire enclosure across my table saw I built a special shoe for my circular saw.  Basically I'm using the saw in a way it was not meant to be used.  Disclaimer: Don't try this at home.  In the pic above you do not see an 8" blade in a 7.25" circular saw.  You do not see a saw with the blade guard removed.

My neighbors always have a nice lawn.

Mahogany veneer.  Maybe I should make coffins.

My favorite part.  A coat of Danish Oil.  Later I applied 3 coats of Lacquer with a cheap HVLP gun.

A case of woofers, a pillow, and a warm afternoon.

For fun I added a few strips of fiberglass duct board to the midrange tunnel.  I ended up using 8oz of polyfill (Acusta-Stuff) for each enclosure.

The back grill is held on with magnets that have been recessed under the veneer.

There are also magnets recessed under the veneer on the front baffle just in case I ever want to add a grill later on.

3" port.  I don't like most bi-wire cups so I installed two R-type Cups.

The 4elevens and the Box of Doom

Continue to 4eleven Measurements Page

Keith Kidder's Audio Site - Home Page