The rationale
behind this project is to reduce the
number of my ScanSpeak 18W/nnnn stock drivers. I
have some 10+ pairs of SS 18W/45-85nn drivers and
cleaning the attic I found a box of pre-veneered
MDF sheets made more than a year ago, ready cut
for a 13 liter vented design, actually the
18W/8542-00 + SEAS 27TFFC, the classic compact
studio monitor from a producer than shall remain
nameless here.
The 18W/8542-00/27TFFC will be the final
construction for sale, including the mahogany
veneered cabinets seen here.
When the 18W/85nn drivers
came about some 15 years ago, everybody
was impressed from the design, the
"ugly" looking carbon-paperpulp
membranes and the huge magnets. The rather slim
chassis allows a 145 cm^membrane area from an
overall 177 mm diameter, quite impressive. All
18W/85nn have copper plated polepiece, symmetric
drive, and a vented centre polepiece. The huge
magnets and low Qt suggests drivers suitable for
10-15 liter cabs and a few small monitor designs
were launched immediately after the release of
the drivers. Since then numerous designs have
been produced and often we see the classic
18W/8545-00 driver used in up to 24 liter vented
or transmission line constructions despite really
suited for smaller cabs. My Amish speakers are
examples of this.
The 18W/8545-00 has an aluminium voice coil
former, where the 18W/8545-K00 has a kapton voice
coil former.
Why build small speakers
when we can have bigger sound for the same money
from a bigger cabinet? Well, the answer is
simple: Because sometimes they must to
be small due to how they will fit in with a given
idea about how our living rooms are going to
look. WAF is high from small speakers. Even if a
slim floorstander doesn't not take more floor
space compared to a mini on a stand, the WAF is
higher for the latter. Not much we can do about
it. Thus this range of Compact Studio Monitors.
"Studio" because it started with the
8542 driver for studio use, by request from a
Norwegian studio ingeneer. The result was the 8542/9500/9700 design,
released last year. Not exactly a studio monitor
suitable for placing on the mixing console. Sorry
it took so long.
How small is small?
Well, the W15CY001/OW1 is
small, the Ellam a little
bigger (10 litres) and delivers a bass
performance leaving the W15 behind. When we add
2-3 litres we may have room for a 6-6½"
driver, a significant increase in membrane area
and we can get a decent bass response down to 50
Hz. Comparing a 18W/8545-00 to a 15W/8530-G00 in
13 litres and 10 litre respectively, we get this
picture:
The 15W/8530K00
may produce a slightly more extended bass
response, but at the expence of ~2 dB efficiency.
Listening to the bass response from W15W/10
litres and the 18W/13 litres - side by side -
leaves no doubt which driver is most comfortable
in this area. I'm not talking about midrange
quality here, only bass.
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