Posted by lon [ 209.103.193.224 ] on April 03, 2005 at 16:31:12:
In Reply to: Re: You Are Correct posted by GM on April 03, 2005 at 01:46:22:
I saw the original MLTL design that Bruce Pea made for the Jordan 92s and he sent me some pics. When we originally discussed this, you gave the dimensions and I averred that this was the size (in general)
of partical board shelving. So the box is that shape, the FE127
is mounted 8" down from the top and chamferred. No stuffing, so it's bare inside.
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?
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