First conceived in 1968 the DM Model 70 was the first 100% in
house designed and built monitor from B&W. It is rare and largely forgotten,
this is not how things should have been.
those of you who don't know it, the DM70 went into production in 1970 and was
manufactured for at least six years. It is a hybrid of moving coil and electrostatic
loudspeaker technologies, it was expensive to develop, produce and ultimately
to own. The technology was unique at the time of manufacture, we like to call
it an "E-brid". The system basically comprises of a 12" bass unit in an infinite
baffle arrangement plus an eleven segment curved electrostatic panel mounted
on top of the cabinet so as to handle the mid - high frequencies. There is an
internal PSU for the panel and a highly complex crossover to marry the two drivers
together. The crossover frequency is set at around 400 - 500 Hz so as to avoid
colouration of critical midband frequencies. There is minimal intermodulation
distortion created by the two technically different drive units.
I believe the B&W DM 70 monitor to be very special, why have
they been forgotten? I have been surprised how little reference this model has
received within the audio circles of which I am familiar. Search Google, no
websites, no fan clubs, almost as if they never were! It is a complete mystery
to me why these speakers aren't given the same kudos as a LS3/5a or a BC1 (sonically
the floor is wiped with most box speakers). These truly are an enigma!
Amar Bizwas (Eminent Audio) had a knack of aquiring esoteric audio
items long before we were all busy searching ebay pages for fulfillment of our
vintage audio fantasies, he had bought his second pair of Model 70s after a
lengthy search. He had owned his first pair in the early 80's and when the second
pair came along three years ago I was told of ultimate build quality, over-engineering
and holographic soundstage merged with prophecies of possibly the best loudspeakers
that B&W had ever built.
Unfortunately for Amar his second pair had lost their original
bass units. Alternative drivers were sourced and Glenn (Croft) helped to tune
the crossover in order to make them work, I was disappointed as I was convinced
that I had missed my opportunity to hear legendary loudspeakers from an era
of British audio where the accounting bean counters were not allowed to impede
the work of loudspeaker designers and sound engineers. Sonic integrity is a
massive part of the design of the these units and the cost of attaining it is
possibly part of their demise.
Sound at the end of audio tunnels
My opportunity came about eighteen months later whilst browsing
ebay pages. The owners were a couple who were fans of 70's design that happened
accross them at a house clearance market in Tunbridge Wells (England).
is safe to say that they did not know what they had and were not especially
into Hi-Fi so the speakers were sat in a house amongst other 70's icons for
five years without actually ever being used as loudspeakers. This was just as
well, as the bass units were in need of professional attention (see Refurbishment). However, my fellow ebayers were aware of the vintage of these
loudspeakers and winning the auction did not come easily.
These loudspeakers really are special. Please read the following pages
in order to get the whole story.
Thanks for your interest, Matt.