frautschi@ohstpy.mps.ohio-state.edu (06/06/91)
Here I would like to report a recent experience that resulted in
a great improvement in sound for a small outlay. Two simultaneous
modifications to the Magnaplanar Tympani I-C are described. I regret
that I did not attempt to determine the relative value of each.
For $143 + shipping I replaced the tweeters and internal wiring
(additional $10?) in the T-IC's, following a tweeter failure, in
February. 8 hours (I work slowly), rivets, a riveter, and a saber
saw are required. (A vacuum cleaner is useful to clean masonite
sawdust from the panels and work area.) Instructions are provided
by Magnepan, with the tweeters. The AudioQuest Type 2 wire was
obtained locally. The resultant improvement in clarity was marked.
These are brighter both in the English and American usages (more
clear, and a pronounced emphasis on the higher frequencies.)
For no additional charge, 8, 4 inch stranded copper wire inter-panel
interconnects were included, at my request. Beyond this I have yet
to replace the Fulton brown wire in the bass panels with the 3
strand AudioQuest. The AudioQuest was chosen because it seemed
the heaviest wire on hand that could be substituted without modifying
the panels and hardware. This was an impulsive choice.
Caveat: No phase markings appear on the tweeter, or explicitly in
the instructions. The drawings, upon close examination, appear to
indicate that the left and right terminals are connected in the
same sense as the original tweeters. I followed this assumption.
I believe that the T-1C uses a 1 pole passive crossover, and
therefore that the phasing is relevant.
Caveat: When removing the original tweeters with the sabre-saw,
cover the perforated metal with tape, to prevent filling them with
sawdust, should you desire to use them in future.
Caveat: The new tweeters are approximately 3cm shorter than the
hole that remains when the originals are removed. Positioning the
active area so that it lies in the position of the originals will
leave a 3cm by 15cm gap at the top of the tweeter frame. I am unsure
of the acoustical consequences of this hole, however under some
lighting circumstances, this hole may be visible through the covers.
I recommend that the user cover this hole with a rigidly attached
(so that it will not rattle) member. I cut a wooden paint stirrer
to the proper length, glued it with Elmer's, and covered it with
black masking tape.
Caveat: I recommend riveting to supplement the Scotch adhesive that
holds the tweeters in place. I drilled holes through the metal
edges and the underlying masonite. The rivet should pass through
to a washer, or something on the other side, so that it will remain
fixed. The rivets should be placed in such a way to cancel rattles.
I recommend that additional rivets be placed until the panel sounds
"dead" when struck with the hand. Presumably, this will result in
a system less likely to rattle, or otherwise color the sound when
music is played.
After break-in or my own mental adjustment, or both, the inner
detail remains, while the brightness seems less apparent.
Prior Modification: All MYLAR capacitors replaced with POLYPROPYLENE
and bypassed with WonderCap ("with DAYNOR", whatever that is.) 0.01
uF.
The new tweeters seem to use the thinner, 0.25 mil MYLAR, and run
a single wire between the magnet gaps. In other words, they seem
to be constructed like newer tweeters, yet are configured for an
8 Ohm system, a possibility that tube amplifier users may wish to
consider. The active area is slightly wider than the original
tweeters. They are plainly marked as replacements for the T-IA,
T-IB, T-IC, T-III and T-IIIa tweeters. More recent units may have
upgraded replacements as well. I recommend that you contact Magnepan.
Hinges, feet, and covers, etc. are available.
Beyond being their satisfied customer, I have no connection with:
Magnepan, Inc.
1645 9th Street
White Bear Lake, MN 55110
(612) 426-1645
(612) 426-0441 (FAX)
Mark Frautschi