"Kappelmeister"
Folded Transmission Line
The "Kappelmeister" design
by V. Capel was first published in the July 1987 edition of Electronics
Today International
ARGOS has experimented
with the basic design using higher powered drivers and implementations
of 2-way and 3-way designs.
The basic idea was
to provide a 1.8m to 2.4m pipe of the same cross-sectional area
as the cone, sitting directly behind the main driver, which
is why the bass driver is at the top in the 2-way versions.
The 10" version required some further changes to get the main
driver to the bottom.
Despite the modifications,
building these is no job for the beginner carpenter. It is
fibbly, time consuming, messy and generally a pain in the
butt. Each of the bigger designs took me about 20 hours/speaker
to make!
First Trials
The first trials
of the Kappelmeister design were done using a pair of
Jaycar 6", 30w polycone drivers and a pair of old tweeters
I had lying around.
They turned
out rather well and had an excellent clean sound with
reasonable bass, given a bit of boost from the amplifier.
However, they lacked power handling capacity and tended
to give up if pushed too hard and loose control of the
bass. They were finished with a pale plywood and oak
edging, (very nice). I haven't got pictures of them.
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6",
80w version
The second
trial was with a pair of 6" 80w Jaycar poly drivers.
These are teamed with Jaycar Response dome tweeters
using a series cross-over network and some resistor
to equalise the sensitivities. Painted with a very
distinctive, lumpy (intentionally) gloss black.
The grills are a simple car speaker type cover.
These
speakers have that very smooth deep bass response
that the folded pipe transmission line gives
8",
120w version
Using a Jaycar 8" 120w
carbon driver and a Phillips tweeter, series cross-over. Initially
timber finished, but it got damaged and they have been re-finished
in gloss black, which also didn't work very well :-((
with fine grey cloth grills.
A very good speaker providing
excellent sound over a wide range of music. They are very precise
and have a wonderful smooth solid bass. They need a powerful amp
to drive them.
Diagram of 8" box design
10" 3-way 160w
version
Using a 10" 160w
Jaycar Response woofer, a 5" Jaycar woofer and a Jaycar
Response tweeter, the cross-over is a 3-way linked series
at 350 Hz and 3500Hz
These speakers
really pack a punch!
The cabinets
are very heavy, requiring 2 people to lift them and
have absolutely no vibration in any of the faces. Hitting
the sides, top, front or back gives a totally dead response,
so the cabinet cannot cause any colouration of sound.
This gives a remarkable clarity of sound, combined with
smooth strong bass. They are a really nice speaker to
listen to.
Diagram
of 10" box design
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