Electronics-World-1959-05

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Acoustic Research AR -3
O
University
Ssromberg- Carlson MSS -491
Some special speaker setups
that represent the various
manufacturers' answers to
the best way to hear stereo.
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'en Model DS100 Fisher "Ambassador 11"
GOOD many loudspeaker manufacturers
have put in a lot of work
A finding out just what "makes stereo."
They may have come up with different
conclusions (which adds to the
confusion), but one can credit them
with honest effort, both for their research
and in making available products
consistent with their "findings."
We discussed the reasons for these
differences in Part 1 of this article -
so now let us consider some other aspects.
Some manufacturers have been
quite "purist" and produced only systems
that give stereo in its best or
"final" form; if you want stereo, according
to them, don't settle for any
half measures. Others have catered to
people who have monophonic hi -fi and
want to convert to stereo by adding a
channel (as a first step, at least) or
for people with practical limitations:
no room for the "conventional" set -up
or an awkward shaped listening area.
"Add-On Units"
Early in the field of the "add -on"
market was Electro -Voice with the
"Stereon." This is a versatile unit intended
to take the mid -range and highs
of the second channel (left or right)
while the bass of both channels is fed
to the bass unit of the original system.
A filter is provided to do this, as shown
in Fig. 7. University has also introduced
three add -on "Stereofiex" units.
42
However, with some University woofers,
the dual voice -coil makes the filter
for diverting bass from the second
channel to the original woofer unnecessary.
One voice -coil of the "common"
woofer is fed from each amplifier output
by a relatively simple connection
(Fig. 5) .
This add -on approach is not favored
by other manufacturers, however. They
feel that in most instances the add -on
unit will eventually be abandoned in
favor of a more ideal system. While
this is probably true, there may also
be some places where "one large, one
small" fit so well they will remain. It
can give quite good stereo presentation,
although admittedly, where circum-
Fig. 5. This is the connection possible
with the University "Stereoflex- as employed
along with double -wound woofer.
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stances allow, better arrangements are
possible.
Another approach that can be considered
as an "add -on" one is the
Stephens " Stereodot," although this is
really a system approach. However, it
can be added on to an existing hi -fi
system by including two "Stereodot"
side speakers (which are very small)
and the control unit. It is an extremely
versatile system because the small
"Stereodot" units can be mounted almost
anywhere. It also provides for
"center fill" by feeding a mixture of
middle and high frequencies to the
original wide -range loudspeaker, as
well as using it for the bass of both
channels (Fig. 8).
A very versatile system in this category
is one used in several Columbia
consoles. This is not so much an add -on
deal as it is a unit with which you can
do many things. Primarily designed as
the master unit of the "Isophonic" system
(mentioned in Part 1) when used
this way the console speaker handles
common bass only, with the left and
right mid -range and highs (above 250
cps) being fed to the small "Isophonic"
units. The difference between this arrangement
and the Stephens system
was explained in the previous article.
Additionally, a jack -plug arrangement
permits the same console to be used
with another full -range speaker system,
feeding one channel (left or right)
ELECTRONICS WORLD