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Nuts&Bolts
Diagram of the UHF platform atop a Hitachi Ultravision television set. The
front (at left) is held up by three stick-on (SSKA) Superspikes. At the rear
are four SSKQ Superspikes, slightly angled.
itself would decouple the speaker acoustically,
while anchoring it mechanically
so that it couldn’t move. The flat bottom
of the Superspike structure would leave
no mark.
Because of the two surfaces we had
to couple the platform to (the front bezel
and the sloping rear shell), we used two
different Superspike models (there are
six variants in all). At the front we used
three of the stick-on models, if only
because they come in sets of three.
Because they’re so short, they wouldn’t
raise the front of our platform unduly.
For the rear of the platform, we used one
of the versions with a threaded shank like
the one shown on the previous page (the
size didn’t actually matter, but we chose
the quarter inch version, since drill bits
of that size are so commonly available).
We drilled holes in our shelf, so that we
could friction-fit the shanks into them.
Note that where you put the rear
Superspikes will determine the forward
tilt of the platform, if any. Put them
closer to the front of the shelf, and you
can make the platform tilt down somewhat.
That’s convenient if you have low
seats close to the TV, because you can
still keep the centre speaker pointing
toward you. Put the Superspikes too far
forward, however, and the platform can
tip backward. With some TV sets, you
may need to bolt another piece of wood,
such as a narrower shelf, underneath the
rear part of the platform. That was not
necessary with our Hitachi, but adding
an extra piece could have given us more
forward tilt if we had desired.
The only really tricky part is drilling
56 ULTRA HIGH FIDELITY Magazine
the holes in the rear of the unit. The
Superspikes must be as close as possible
to being perpendicular to the surface
below. That means the rear holes we
drilled had to be angled. It’s important
to get this close to right, because if you
tilt the Superspike too much its two
internal parts will touch, and it will be
ineffective. A protractor can let you get
this exactly right, though it's possible
to gauge the angle by eye if the tilt is
not too pronounced. To protect the TV
casing’s surface, we added the included
adhesive felt pads to the bottoms of the
Superspikes.
The platform was now a perfect fit.
We saw that it could not slide forward,
because the rear Superspikes would prevent
that. It could, however, certainly
slide backward. To prevent that, we
purchased a pair of inexpensive stick-on
doo-dads and placed them behind two
of the four rear Superspikes, to prevent
the platform from moving back (see the
photo below). Our dood-dads were towel
holders, as it happens, but one of those
ubiquitous adhesive hooks will work fine
too.
Of course the speaker needs to be
stabilized as well. We held it onto our
platform using copious amounts of
Audio-Tak, pressing the speaker down
on it hard. Note that if you use more
of it at the rear than at the front, you
can increase the speaker’s forward tilt
slightly.
All that was now needed was to rebalance
the speaker volume, which we did by
placing an omnidirectional microphone
at viewer position, and asking our Moon
Attraction processor to take care of this
little task for us (see the extensive review
section in this issue).
The resulting performance was
excellent. The balance among the five
speakers was far better than we could get
with the lower front position, and there
was no sign of rattling even when we ran
the biggest of the speakers at high level.
Slapping the speaker hard did not elicit
any ringing from the TV. Even a large
speaker, such as the Thiel or the ProAc
reviewed in this issue, felt reassuringly
steady.
Shielding
It is common to look for “shielded”
video speakers, ones designed not to
have a strong magnetic field that can
upset a direct-view TV tube. Shielding
can be accomplished with an internal
metal cage, or — much more commonly
— with added magnets intended
to cancel the woofer’s own magnetic
field. Because both techniques result in
a performance hit (and possibly because
they’re expensive), shielding is often
minimal.
The platform may add just enough
distance so that even an unshielded
speaker will not interfere with a directview
TV. If it doesn’t, it may be possible
either to place a steel sheet under the
speaker (it must be magnetic, not stainless
or some other non-magnetic alloy),
or else to double up on the shelves to
get more distance. You’ll need to experiment,
because some sets need more
shielding than others.
We were prepared to make this a
complex project, but as it turned out we
didn’t need to. Anyone who has done
even the most minor home maintenance
can probably build a platform just like
ours in an hour or two, possibly including
the shopping time. You’ll be happy
you did.