Electronics-World-1959-05

Hi -Fi Product Test Report
NEW RIBBON MICROPHONE
THE Ercona Corporation has just announced importation
of the "Mark III" line of British -made Reslo studio
microphones. Included in this line are various models with
the differences being mainly in output terminating impedances.
Our particular interest, since they are all of the ribbon
type, was in determining first -hand the durability of these
microphones. There have been comments within the industry
that ribbon microphones today are not as delicate
as they were in years gone by. We tested one of the models,
the CRH, which is designed for high -impedance output,
by dropping it several times from a height of four feet
directly on to a cement floor without it exhibiting any
deleterious effects performance -wise. This obviously backs
up the many comments we have heard. In the event that
the ribbon element is damaged, the ribbon cartridge is
detachable and replaceable.
Although these microphones are designed for p.a. applications
as well as studio or home recording, care should
be taken when used outdoors. The adverse effects of a
strong blast of air against the ribbon still remain a problem.
In the case of this microphone, however, the ribbon
is shielded by nylon and wire -cloth screens and the perforated
shell. Proper rotation of the microphone will, of
course, alleviate part of this difficulty.
According to the manufacturer, the frequency response
of this microphone is basically linear from 20 to 15,000 cps.
Its characteristics are bi- directional but this may be altered
by use of internal pads. Its bi- directional effects
vary with frequency: at 1 kc. it has 2 db more sensitivity
in front and at 10 kc., 20 db more. This feature can be
used to advantage since the rear can be employed for low -
frequency pickup and the front for the higher frequencies.
The output level is -58 db. Although our tests were
limited (as we did not have an anechoic chamber available) ,
we feel quite confident that these microphones are entirely
suitable for top -quality applications.
Prices, depending on the model, range from $64.50 to
$84.95, audiophile net.
ELECTRONICS--
LAB TESTED
HIGH- COMPLIANCE SPEAKER SYSTEM
[OR those who are interested in a compact, high- compli-
I ance speaker system, we would like to call attention to
Allied Radio's "Knight" KN -2000. The system incorporates
a specially designed 12 -inch woofer, an 8 -inch mid -range
unit, and an exponential- horn -loaded compression high -
frequency tweeter. The enclosure is fully sealed and lined
with acoustic material. All three speakers are fed by a
three -way crossover network with an externally operated
control to adjust the high- frequency level. The system
has an input impedance of 16 ohms and will handle 20 watts
average power. It is a compact unit measuring 1375" x
2615" x 12,'4" and is available at a cost of $84.50.
The speakers used in the "Knight" KN -2000 system have
obviously been made especially for this unit. The woofer
seems to be extremely well designed with a long -throw
voice coil and, as is usual with units of this type, it has
an extremely low resonance frequency -approximately 38
cps unmounted. The mid -range speaker seems to be a
fairly conventional unit except that the basket is a complete
solid enclosure around the cone, producing a hermetically
sealed chamber. The tweeter appears to be a conventional
type.
The over -all response is quite smooth,
particularly at the low- frequency end.
The system does not have the exaggerated
bass that can be found in some
bass -reflex type speaker enclosures
which, incidentally, some people may
prefer. Audibly, the system seems to
take hold at about 55 cps and extends
at the high end beyond this reviewer's
limit of hearing.
To be extremely critical we did note
a slight attenuation of response between
100 and 200 cps and at approximately
2000 cps. Again, only a very
critical ear could determine this and
then only by A -B testing against another
speaker unit known to be flat in
this range.
Another point of importance concerns
the efficiency of the speaker system.
Normally, high -compliance units
go hand -in-hand with low efficiency.
Apparently, and justifiably, Allied has
compromised in this case since the efficiency
of the system was not as low
as was expected.
STANTON STEREO "FLUXVALVE" PICKUP
cartridges are still coming in at a high rate.
STERk.:0 We have four on the bench now awaiting our tests. The
most recent one checked is the Pickering Model 371 "Flux-
valve." It is a moving iron magnetic type and is an improved
version of a previous model. The pickup has a .7
mil diamond stylus and is recommended for use with a
tracking force of three to six grams. Our tests showed
that it has uniform response up to 3000 cps, dropping
slightly by 1.2 db at 7000 cps, followed by a resonance that
increases the output to +4.2 db at 12,000 cps. Response
then drops off rather rapidly to 15,000 cps. The sharp
rise is inherent in quite a few of the cartridges we have
tested in the past and, according to Pickering, it is not
detrimental since it is at the very high end. Actually, this
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