일전에 오디오곤에서 NICETOM이란 아이디를 쓰는 사람이 아젠트 룸렌즈를 집에서 자작해서 써보곤 효과가 있더라고 자랑하며 원하는 사람에겐 제작법을 알려주겠다는 글을 올린 적이 있었답니다.
그다지 손재주는 없지만 관심이 가길래 메일로 제작법을 보내달라고 부탁하니 아래와 같은 글을 보내주더군요.
문수만님 제작하시는데 도움이 되시길 바라며 원문을 첨부합니다.
그리고 http://members.nbci.com/Jon_Risch/catch2.htm 로 가보시면 아랫부분에 아젠트 룸렌즈에 관한 언급이 있으니 그것도 참고하시구요.
DIY ARGENT ROOM LENS CLONES: INSTRUCTIONS
I. Overview. The finished product will have a base L = 12", W = 6", H =
4". (All dimensions are in inches.) The base will hold three PVC tubes
60" long, and the completed Lens will stand about 61" high, since the base
will have 1/2" feet and a raised bottom plate into which the tubes fit.
The tubes will lie in a line, differentially spaced from each other, and
filled with differing amounts of Fiberglas. Their openings at the bottom
will be partially restricted. They will be held in place at the top by a
tube holder whose holes correspond to those in the top and bottom plates of
the base.
II. Tube size. I use PVC tubes, obtainable at Home Depot, Yardbirds and
the like, of outer diameter (OD) 2 3/8". This is called 2" tubing, and the
inner diameter (ID) is about 2". My basic design could be scaled up or
down. to use tubes of larger or smaller OD, but 2 3/8" is surely the
closest to the size used in the Argent Room Lens, and is probably the best
choice.
Such PVC tubes come in 10' lengths. I recommend taking your own saw to the
store (since they may be unwilling to cut them for you) and cutting three
10' lengths in half, as precisely as you can. Pick tubes with undamaged
ends: these are the ends that will show in your finished Lenses.
III. Drilling or cutting holes in the base top and bottom plates and the
tube holder. I use 1/2" medite for the front, back, sides and bottom plate
of the base, and 1/8" masonite for the top plate of the base and the tube
holder. I have an old-fashioned brace and bit drill that I use to make the
2 3/8" holes. A hole saw might work too, certainly for the masonite, but
it might be hard going through the medite. I clamp together two pieces of
1/8" masonite, each 12" x 6", and a piece of 11" x 5" medite 1/2" thick (or
3/4" thick if you prefer), with the medite carefully placed precisely 1/2"
in from the masonite pieces, on every side. Mark the sides that were "up"
for the drilling, and have both smooth sides of the masonite "up". One of
these two masonite pieces will be the top of the base, the other will be
trimmed to a smaller size to become the tube holder.
Hole centers on the 12" x 6" top, as measured from one end, are: (1) 2
11/16", (2) 6 3/16", and (3) 9 5/16". This puts the centers for (1) and
(3) each 2 ll/16" from an end. The center for (2) is 3/8" closer to the
center in (3) than it is to the center for (1), which makes for distances
between tubes of 1 1/8" between (1) and (2) and 3/4" between (2) and (3).
These distances were arrived at crudely, simply by looking at the picture
in the Stereophile Argent Room Lens review. In general, I think my copies
are a bit "scaled up" from that commercial product. But even without
understanding very well why or precisely how they work, I'm confident that
any differences between mine and theirs will result in no more than a minor
shifting of the frequency range significantly affected.
IV. Building the base. I make the front overlap the sides and the sides
overlap the back. Using 1/2" medite, I make the front 12" x 4", with the
1/2" thickness thinned (on a table saw) to 1/4" starting 1/2" back from the
inside ends. (So the outside of the front is 12" long and the inside of
the front is 11" long.) The sides are 5 3/4" x 4", with similar thinning
of one (but not both) of the ends. The back is 11 1/2" x 4". With these
overlaps, the four-piece box ends up as 12" x 6" x 4".
You could instead let both front and back overlap the sides, for a base
with front and back the same. If you don't do it this second way, your
finished Room Lenses will each have a front and a back뾲hat is, a surface
that's supposed to face forward뾞nd you should then be sure to achieve
mirror image symmetry for the holes when you position and glue in the 1/2"
medite bottom plate. You'll want this symmetry when you place the Lenses
in relation to you speakers.
The thinning to allow some pieces to fit into "notches" in others should
come in from the end of the thinned piece a shade more than 1/2", so the
joint can be made perfect by a little sanding. It's a lot harder to make
it perfect if you have to change the thickness of the fitted-in piece by
sanding.
The bottom, with its three OD 2 3/8" holes, at 11" x 5", should fit tightly
inside the box formed by the front, sides and back. Accurate cutting is
important to get a good fit here.
V. Putting the Base Together. The bottom plate should be placed 1/2" up
within the box. To accomplish this, glue small squares of 1/2" medite (1"
or 1 1/2" squares) onto the corners of the bottom plate before you glue
that plate into the box. (I use a wood glue, Titebond or the like, except
when gluing to the tubes, where epoxy is a better choice.) After that glue
is dry, assemble the front, back, sides and bottom plate together, and make
some fine table saw adjustments, if necessary, to insure a good fit.
Needless to say, accurate sawing is crucial to success with this design.
Next, glue together the 4" high pieces: the front, back and sides, and at
the same time fit the bottom plate inside them and glue it in, with the
squares glued onto its corners facing down. The bottom plate will be held
1/2" up within the box, if you let the glued box dry sitting on a flat
surface. For clamping while the glue dries, I use large rubber bands. Old
bicycle tire inner tubes, often given away free by bicycle stores, can be
tied and used as rubber bands, once the valve portion is cut out.
The last step in building the base, which you can save for later, is to
glue 2" squares of 1/2" medite onto the bottom corners, to serve as feet.
I painted my Lenses white and made these feet black, painted before being
glued on, which in effect makes the feet disappear.
VI. Installing the tubes in the base. Reminder of terminology: the base
is the five-sided rectangular medite box, L = 12", W = 6", H = 4", with
three round holes in its bottom plate, the top is the 12" x 6" piece of
masonite painted on one side, and the tube holder is the other masonite
piece, which at this stage is also 12" x 6". (It will later be trimmed to
a smaller size.)
I use slow-curing epoxy to glue the tubes into the base. The three tubes
you insert in the base will not be precisely the same length. Identify the
longest of the three. Apply epoxy to all three holes in the bottom plate,
then insert the longest tube into the middle hole of the base, a full 1/2"
(the thickness of the medite). The other two tubes can be inserted a little
less far into the medite뾵hatever it takes to get all three tubes the
precise same length coming out of the top. Tube ends can be moved a short
distance in the holes in the base by twisting while pulling or pushing. Be
sure to insert the sawed ends of the tubes into the bottom plate, so that
the unsawed ends will be the ones that show. Then place the base top over
those unsawed ends, the ends away from the base, about 1" in from those
ends, so as to make the three tubes lie parallel to each other.
Getting the tubes the same length is easier, checkable by using a
carpenter's square, once they are perpendicular to the base, in two planes,
the width plane and the length plane. Place the base near one corner of a
large rectangular table, with the 12" length of the base precisely parallel
to the width dimension of the table, so that the tubes, now inserted in the
holes in the base, will run parallel to the length dimension of the table.
Be sure that the top, in which the other ends of the tubes have been
inserted, is perpendicular to both the tubes and the table. This should
insure that the tubes are perpendicular to the base along its width
dimension. But it may not. So after setting up the base, tubes and top in
this way, you should measure the distance from the table, at both ends of
the tube, of tube close to the edge of the table. You could do this by
sliding a small rectangular piece of medite under the tube, once near the
base and once near the tube end farthest from the base, and "eyeballing"
how close it comes to the bottom of the tube. Then use folded-up paper or
the like to make an adjustment at one end or the other.
To get the tubes perpendicular to the long dimension of the base, move the
base, tubes and top together, so that the tubes, both near the base and at
the end farthest from the base, are 3", say, from the table's edge, as
measured by a pair of 3" wood or medite blocks. If the length of the base
is also precisely parallel with the end of the table, the tubes will be
perpendicular to the length of the base, as desired. You are trusting the
rectangularity of the table to insure this. Roughly, you make the 12"
dimension of the base parallel to the width dimension of the table, and the
tubes parallel to the length dimension of the table. This can easily be
done with quite good precision.
VII. Placing the top, and trimming and attaching the tube holder. After
the epoxy holding the tubes in the bottom plate has cured, slid down the
top, the masonite piece through which the unsawed ends of the tubes were
inserted, closer to the base. It will be attached later. Trim the tube
holder to a desired size and shape. (Mine are roughly 10" x 4", with
heavily rounded corners.) Glue the tube holder onto the very tops of the
tubes, using slow-curing epoxy. If the tubes are all precisely the same
length, measured from the base, a neat fit will be possible here.
VIII. Filling the base, attaching the top, finishing. When the epoxy has
thoroughly set, the structure can be set upright and the base can be
filled뾵ith sand, cement, or whatever. (The Argent Room Lens people say
they use "dark matter".) The lid can be attached after this is done, with
wood glue and small finishing nails: I put two near the corners of each 6"
end and three or four each along the 12" front and back. The lid may not
fit perfectly over the base, but as long as the misfit is under 1/4" it
will cause no problem뾬ther than a need for more sanding. A bevelled edge
is attractive anyway, and I recommend a fair amount of sanding, to achieve
a bevel, even if the lid does fit quite well. Make sure the small nails
are centered in the 1/2" thick medite sides.
Painting is no problem except for the sides of the tubes that are close
together. For this location I improvised a very thin roller, using a fat
plastic drinking straw, with porous cloth wrapped and fastened around it,
and two long nails as handles. The tubes can be painted in advance, but
sliding the top down into its final position will scrape some of the paint
off. Spray painting might offer the best solution, but I painted my lenses
with brush and roller and the results weren't at all bad.
IX. Positioning. The makers of the Argent Room Lens suggest a position
flanking the speakers on the outside, toed in a little more than the
speakers are. But they encourage experimentation too.
