June 2010
Otto's Major Demonstration
We should like to thank Otto Major for demonstrating his custom upgraded Quad ESL 57 Electrostatic Speakers at our May 2010 ASoN meeting. This type of speaker is still not exactly common but the ESL 57 does indeed occupy a special place in Hi-Fi folklore. While Peter Walker of Quad did not invent the ESL speaker, he made the first commercial full-range ESL. Earlier patents were, if my memory serves me right, held by Jantzen and Kellogg.
They say there is more than one way to bake a
cake – or you may think of similar analogies. But there is also more than one
way to make a loudspeaker. Well, back in those days of 1957 not too many would
have even thought of electrostatic speakers. Speakers were those things made
with wire coils and magnets, otherwise known as dynamic speakers because they
worked like a dynamo-in-reverse. A dynamo is really an electrical motor (dyna
as in dynamic and mo as in motor), one that driven by electricity or a motor
that produces electricity as the dynamic motor also works in reverse. For
example, hook a speaker up to the microphone preamp and speak loudly into it,
and presto, you have a microphone, albeit not a good one, but a microphone
nonetheless.
Then in 1957 a certain English gent we now know
as Peter Walker came around with a somewhat different idea. Why not use a film
with a conductive surface, one that could be made much thinner and lighter than
a paper cone and make it large enough
to be a full-range ESL. This is where
he was first; not just making an ESL, but one that could produce a modicum of
bass. Low mass would mean faster acceleration and potentially lower distortion,
and also force driven across the diaphragm rather than the single apex of a
cone. Instead of using a coil and the dynamo principle, this conductive
surface, the diaphragm, would move due to an electrostatic force that could be
modulated in sympathy with the music it reproduces.
What is an electrostatic charge? It is the force
created when two closely approximated elements (or three when in push-pull
mode) are charged by a large separated DC voltage. This creates a stationary
force with a specific tension between the two in proportion to the distance and
voltage potential. Vary or modulate one of them and there is a tendency for the
lighter of the two elements to move accordingly, either away or towards each
other. The more consistent the charge was over a range of movement, the more it
would become linear with bass included.
For this reason the speaker Mr. Walker developed
ended up with three elements, two stationary ones called stators, and in the
middle of the stators was a suspended conductive film. This meant that
electrostatic forces could be applied and the film would move and create the
sound. Needless to say and this is critical, the two stators needed to have
holes, lots of holes; otherwise the
sound would not get out. Later Otto would realize that this was a limitation of
the Quads that could be majorly
improved (pun intended). For this reason the stators can also be called grids.
The thickness of
the diaphragm and grids has been exaggerated for the purpose of illustration.
These are the basic elements of an electrostatic
speaker. The principle of operation is simple enough; the only moving part is
the diaphragm. We can see the EHT, the Extra High Tension typically measured in
many thousand volts. A step-up transformer then causes the difference in the
charge to vary. The example shown is push-pull as the better electrostatic
speakers are. The principle would also work with a single stator but would
quickly become non-linear with any significant movement of the diaphragm.
We all know that our own Otto Major (hope he
doesn’t mind me saying that) has been a long time proponent of electrostatic
speakers, especially Peter Walker’s original Quads. Indeed I know a number of
members over the years who have owned Quads. My own memory of first hearing the
Quads is notable to me as I heard a stacked pair demonstrated by Allen Wright
at the old Sydney Showgrounds in 1975, in the building that is now the Fox
Studio Sound Stage where the Star Wars movies 5 and 6 were shot. That was the
first time I met Allen – and the Quads made an immediate impression. I did hear
that amazing lock-in imaging and it was nothing like I had ever heard before.
Otto
himself, as
he explained, first heard the Quads in the 60’s and it has clearly been a life long love affair. But Otto’s real contribution has been to extend
the life of these treasured speakers, rebuilding and indeed improving them.
This now includes his own replacement treble panels; these are not just
improved but also able to take more abuse. The old Quads sure could arc very
easily and be damaged quickly.
Otto’s version of the Quads had its public debut
at the Hi-Fi Show, Artarmon Inn
Being open
weave we no longer have a limitation on the number of holes. We now also know
that Stax Electrostatics uses brass mesh too.
Otto did explain that the beaming for which the
Quads are famous, or infamous, is indeed also an asset. He is not in favour of
the modern idea of bending the panels a la Martin Logan. The flat ESL cuts outs
a huge amount of side reflections and also floor and ceiling reflections. This
gives the ear a better chance of latching on to the leading edges of the music
as per the Haas Effect that governs how we perceive delayed and phase shifted
sounds. In the right listening position this can effectively shut out many
defects of the room. But it also makes it a one-person-love-affair.
While I have no wish for this meeting report to
be a review, this much was apparent; not too many in the room would have heard
this, but if they had been sitting right in the middle in the second or third
row, the Quads were the only speaker I have heard in that room that was able to largely shut out the room effects.
This is what Otto was getting at.
The beaming can often overcome these
limitations in a way that other speakers cannot. Our Haberfield exhibition hall
has so many fuzzy random and long term (time wise) reflections that throws me
and makes me feel less than likely to make firm comments or pontificate on any
judgments of what I hear. But when sitting in the right place the Quads did a
very good job, better than any other speaker I have heard in that room.
So I enjoyed the demonstration very much. It
isn’t as if we did not hear any limitations the Quads have. Even Otto admits
that while improved and also less likely to be damaged when playing at higher
levels, this is still in my book the Achilles Heel, the lack of upwards dynamic
range. I had a couple of my own selected songs played and there were moments
when the demand of that selection of music exposed the lack of headroom. They
can only go so loud before they show discomfort. But at least Otto’s version
does not get destroyed when overloaded like the originals did.
But there is a solution that will help a great
deal towards the lack of real headroom, stacked
Quads. Also twice the cost etc, but it also means the Quads can go a lot
louder, by about 6dB. It also extends the bottom end noticeably by reducing
front to rear cancellation at low frequencies.
I asked Otto how much he charges to upgrade a
standard pair of Quads in an already reasonable condition. But even when in
working order there will be things to get attended to, likely in the bass
panel. The treble panel is entirely replaced. But it is possible for the
upgrade hopefully to be around $3000 per pair.
Once again I would like to thank Otto for his
efforts over the years and for allowing the membership to hear his speakers.
The original Quads will always occupy a special place in the hearts of many of
us. Likewise thanks to Elson Silva for supplying the equipment support. I
especially liked the high-tech speaker stands.
