If the specs are close, adding a total of 8 ohms series R will 'fill' a 2.50ft^3 box tuned to Fs. Add BSC as required. Looks really good in a ML-TL.

GM

Sometime in the future I hope to do a side-by-side comparison with some other single driver speakers including Omega speakers, Lowther Medallions, and Third Rethm speakers that are owned by fellow members of the Lone Star Bottleheads. I have found this kind of comparison using a small group of experienced listeners is an especially useful exercise because it gets comments from listeners who are not biased by ownership of one or the other (as I tend to be). I'll post a summary of my conclusions.

Listen to Greg. He knows his MLTLs.

Glad to see you on here btw. My build of your MLTL for Fostex
FE127e is getting finished off. I fiddled with these for quite
a while-- no test equipment, all by ear. Bare inside. 2x6 in
PVC port with your measures.

I have followed this discussion of the Nirvana speaks for
a while now. Would a test of both units of a stereo pair
be necessary to prove any variances in manufacture?

Bare?! Anyway, I've done several different designs, but none I kept specs on require a 2" dia. vent, much less 6" long, so I'm curious what you built and the room, etc., details that would dictate such a vent.

GM

Exact dimensions are: 7 3/8 w x
23 in. h x
4.5 in. d all inside dimensions.

I used a couple of different pieces to make the bottom:
drilled out 1 in. hole and used some plumbing parts to make various port lengths. Also tried getting the port length to spec
by using a sandwich of 2 particle board pieces to get 1x 1.125in.

At least one of the original MLTLs have the port for the
Jordan 92s extending out the bottom and a baffle at 45d built into
floor-standing design with the port extension masking the
baffle.

Well, I only had those pieces of shelving which did not need a
lot more cutting to get to finished size.

I did my listening tests this way:

You know those $10 screw together melamine lamp stands that have
3 shelves and are about 11x11x30 in high that they sell at every
discount store you can name? Ok. I used my 2 in hole saw that
I got for the PVC and drilled through the center of the top
shelf. So the port slides through that and _e' voila_
speaker and stand.

To test I listen to organ recitals, classical and jazz shows, and dvd. What I was getting with the stubby small ports was a very
muddy lower end. This is greatly improved with the 2x6 port.
Clarity of string bass and even those boomers on the organ
recital come through for me in this arrangement. It's not
scientific.

As to stuffing, I tried what you had mentioned which was
putting something directly behind the driver, but anything
inside seemed to interfere with that clarity I was looking for.

So the end result might be that the FE127e is losing something
at the lower end but the overall effect is the best I've found
for the music.

I do not have a shop but I remember you helped me a few
years ago over in FRDF (Full Range Driver Forum by
James Melhuish). That same pair of FE127s became my first
project: modifying some mini speakers from Nakamichi
by mounting the Fostex, plugging up the port hole and knocking out
the backs. I ran that set for a pretty long time at
the computer.

If I had the proper port baffle set up, I think that
that would be the best conclusion to the project. After all
the tweaks are found, I'd like to do this build as more
than a prototype-- in poplar perhaps.

The room is 14x18--pretty big-- some old style apartment with
a large living area. No wall coverings. I am not knowing
how the walls play into this concept very much.

While you're here I'm wondering what your opinion
would be of the Tuba 24 over in Bill Fitzmaurice's Forum. The
builders there rave about them. The Tuba 18 is a project recently
written up for _audioXpress_. These subwoofers get a lot of
horn path in not very much space.

Lastly, Bruce mentioned you had discussed the "thump test"
with him to test a box. Could you describe that for Audioroundtable?

• Project page for Tuba 24 *pics*

Now, is everyone sitting down? I don't want anyone to faint and sue me. The 2.5 ft enclosure has two ports that are 3" diameter by 3/4" long - the thickness of the enclosure material. Soooooooo, these things are tuned to about 71hz. Theoretically this should provide about a 2dB dip at 140hz and a 3dB peak at about 70hz, dropping off the edge of a cliff below that. These may be box speakers, but David definitely is thinking outside the box. Kinda reminds me of when Galileo said the earth isn't at the center of the universe, or when I announced to my devout old school Catholic parents and my Great Aunt, Sister Victoria, that I was marrying a Protestant girl. I like it.

I still plan to build these to spec and listen with an objective mind. I can even experiment with longer port lengths with pieces of 3" PVC pipe that I already have in the garage from building the Eros MKII's. So many speakers, so little time.