The Triune TL
An All Dayton MTM Transmission Line
Click on drawings for a larger image
Woofer network
Tweeter Network
Design Particulars
Using Martin Kings equations, So/Sd calculates to be 5.58.
With the Sd of the two drivers being roughly 28"^2, this results
in an So of 156"^2. Since this would result in an unacceptably
large enclosure, I reduced So by roughly half. With So
=76.5"^2, and a terminus of 24"^2, this gives us a taper ratio of
3.18 to 1, or an Sl/So of .314. Expressed in terms of Sd the
taper is 2.75 Sd to .86 Sd. The tuning frequency is
approximately 46 Hz, and the enclosure volume approximately
24 liters.

Construction and stuffing suggestions:
Many thanks to my good friend Wayne for constructing the
gorgeous piano black finish enclosures. I am told that the
enclosures are quite simple to construct and a pair can easily
be made from a single sheet of 3/4" MDF. To further dampen
side panel resonance, two dowel type braces were added
behind the drivers. Acoustic foam was applied to the enclosure
above and behind the drivers. The crossover was attached on
the angle of the fold directly below the terminus.
I used polyfill to stuff the lines, but certainly you can use
fiberglass, acoustistuff, or whatever strikes your fancy. In
addition, acoustic foam was glued to the top and back of the
line behind the drivers before they were stuffed. I found a
medium fill behind the drivers and a light to medium fill from
below the drivers to the bottom, leaving the terminus open,
gave the best response for my taste in my listening
environment.  Start out with approximately 1.5 ft^3 of polyfill
per enclosure and stuff to taste.

The Crossover:
The crossover is identical to the crossover as the Triune CC,
with the only difference being the removal of the 1 ohm
attenuation resistor in the tweeter network. This is likely
required due to the longer baffle providing additional bass
support for the woofers. The Woofer network remains the same

Parts notes:
All caps and resistors are specified as Parts Express parts, but
certainly you can substitute your favorite brand. The inductors
specified are Jantzen 18 gauge air core. Note the parts
quanities are per speaker.

Listening impressions:
The Triune TL exhibits very nice open sound, with good
resolution and detail, and excellent bass extension. Tonal
balance is slightly warn and the bass is surprisingly tight and
deep for a 5 inch driver. In my listening room sub-40 Hz tones
are easily audible. While these do not sound as good as my 3
ways, they certainly give them a good run for the money, and
considering they are 25% of the cost of my 3 ways, probably a
great value as well.

Copyright 2004 Curt Campbell
Parts list per speaker
Enclosure Drawing
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