Quad ESL-63 Introduction
These are my Quad ESL-63 speakers. These are the main front stereo pair in
my current 5.1 home theatre system and have held that position for over 21 years
since 1983! There is no competition from anything that could possibly
replace them! ESL stands for Electro Static Loudspeaker and 63 stands for
1963 (when I was 1) when Quad first started the design. People have either never heard of them or have always wanted
to see & hear them and they are surrounded by more mystery and misinformation
than any other Hi-Fi component on earth. Either way, once seen & heard,
everybody has something to say about them and I have had the pleasure of
listening to them for all those years and hopefully many more to come! I
bought them new from University Audio in Cambridge England just before Christmas
1983 at a cost of 1100 GBP
and they were serial numbers 11089 & 11090. I had a small vibration problem with the
original pair from the shop which I now believe to have been the dust covers.
I was listening to a digital remastered CD of Pink Floyd's "Dark Side of the
Moon" (this is in 1983, think about that!). At the beginning where there
is only the sound of the heart beat, I could hear a kind of fuzzy rattle.
This was solved by Quad personally delivering a brand new pair tested at the
factory that day direct to my house in Cottenham, near Cambridge, just a short
distance form Huntingdon where they are made. These are serial numbers 13009 &
13010 delivered January 5th
1984 by Richard Ramsay from Quad, so some 1000 pairs newer than the
originals. Richard and I sat there and listened
to the CD on the new speakers with my Sony CDP-101 CD player and
Technics SE-A5 amp.
Remember at that time, only a handful of people in the world had even seen a CD
player let alone listened to a Pink Floyd CD on electrostatic speakers! We
just sat there in total awe of what we were listening to. The only thing I have done to them was
in 1994 when I replaced the grill socks with a black version that
Susan made and sprayed the base & top in
black satin to update their appearance a bit. Originally, they were teak
with brown socks as shown above. They have only gone out of production in
recent years and are now replaced by the
The last few that came into the U.S.A. were sold for around $6000 a pair!
I could actually sell them after more than 21 years of use for more than I paid
for them new! However, don't even bother asking - I will never ever sell
them! The only issue I could possibly describe as a problem is their cost
and this is of course why they are not more widely known and used although there
are plenty of more expensive speakers around. While suited to classical
music because of their superb mid range and treble but modest bass, I can tell
you that they are just as good for pop and rock music where vocals sound like
never before especially when used in a system with a subwoofer.
Because of this, some people actually think that Quad ESL-63's can be somehow
damaged by listening to loud rock music. This is total poppycock and I
have been rocking my ESL's hard for years with no problems whatsoever!
What makes ESL-63 speakers special
They have no
moving coil or electromagnetic drive units!
They have no cabinet!
On a sunny day, you can see right through them!
There is no built in amplifier, but they have to be plugged in!
They have the profile of a bar of chocolate!
They are a 1-Way speaker system!
The diaphragm is 1/10 the thickness of a human hair!
I consider them to be the best speakers in the world!
How ESL-63 speakers work
Clearly, the ESL works in a totally different way to a conventional loudspeaker.
While most speakers work with multiple moving coil hard coned type drive units, the
ESL uses a very thin flexible
(polyester film) membrane diaphragm that is one-tenth the thickness
of a human hair! The diaphragm has a special conductive coating and is stretched
between two electrode plates. Relative to ground (Earth for the English),
both electrode plates have a high positive charge of about +5000
volts, but there is a
slight difference in the charge on each electrode. This difference causes
the negatively charged membrane to be more attracted to one than another, thus
causing the movement of the diaphragm. As the diaphragm is mounted on an
open frame, it is free of any coloration from a cabinet because there is no
cabinet, and because the diaphragm acts as a full range driver there is also no
need for a crossover! This means that it is a dipole speaker where the
sound emanates from both sides at the same time but with inverted phase.
It can move more delicately than the smallest tweeter and is larger than the
largest woofer to give reasonable bass, all from just 1 driver that is virtually
weightless! There are absolutely no discontinuities in the frequency
response curve, so you get the full musical spectrum from the single diaphragm,
just as it was recorded. Because the speaker is a dipole with no cabinet,
the bass is not quite as good as a speaker with a box of the same size,
but that makes no difference in a 5.1 system these days as you always have to
have a large subwoofer anyway. Quad
sometimes refer to this design as FRED meaning Full Range Electrostatic Dipole. By
using a series of 7 concentric annular ring, anode electrodes, rather than just
two plates, the Quads are able to produce a spherical sound pressure pattern on
the diaphragm that gives the effect of producing a ripple like a pebble dropping
into a pond. The signal is fed to the series of electrode rings via delay lines, so
each ring responds to the change in charge a split second after the previous
ring creating movement in the diaphragm identical to the ripple in the pond.
So the diaphragm is not just moving forward and back in one solid piece, but is
reproducing the fluid movement of air that would occur at a distance of about 1
foot behind the plain of the diaphragm from a point source of no dimension.
All in all, because of this unique design that has no solid resonance in the
diaphragm or any cabinet, the sound reproduced it totally uncolored and very
transparent with incredible stereo imaging. There is nothing else on earth
that sounds like them because quite simply, they sound like nothing at all!
Inside the base of the
ESL are all the electronics that charge up the electrode plates and the delay
lines that feed the signal to the anode rings. There are 7 rings on each
side so 6 delay lines are needed for each side so that the signal can be applied
at the 7 points in time needed. These are the 6 orange things on each side
at the top of the picture. The first ring gets the signal as soon as it
comes in so there is no delay line needed for that. The two large
transformers are for stepping up the 120 or 240
volt AC input up to the 5000 volts DC needed for the electrode plates on each side.
In the center are the protection circuits. There are two of these and
there is a very good reason why they are needed! As you can imagine, with
up to 5000 volts of electrical potential between the electrodes, a spark between
them would be like a thunder bolt blowing through the diaphragm! Inside the
pedestal is an antenna that detects when the air gets ionized just before
sparking is about to occur. When this happens, the protection circuit short circuits the input of
the speaker leaving a 1.5 Ohm load for the amplifier. Wow! This sure gives
the power amp a shock! As well as that, there is a soft clipper that
starts distorting the signal at about -3dB as a warning. Because of this, some
people say that the ESL-63's are not good for playing loud. This may be
true if you have a very large room, but I have never had a problem in any of my
setups and I listen to loud rock music all the time. My wife Susan usually tells me
when I am going too loud and she always activates before either protection
circuit! When the protection circuit shorts the input of the speaker, in
most cases when using a large power amp like the
Technics SE-A5, the amp just keeps on going
if it is not running at too high a level, otherwise the amp will activate it's
own over current protection and there will be silence for a couple of seconds.
If the amp does not trip out, the signal can still be heard coming from the
speakers but because the load is now so small at 1.5 Ohms the distortion becomes
quite high so this can sound rather strange. Usually, the only time the
protection circuit will activate is if there is some spike on the mains power.
With such a large step up (almost 42 times with 120V AC) a high spike at the
input could cause 1000's of extra volts to appear at the electrodes and
potentially cause sparking.. This can happen if switching a motor on or
off for example like a vacuum cleaner or a refrigerator on a circuit close to
the speakers. Some simple planning with regard to what is plugged in where
and some basic filtering on the supply can prevent this problem.
Wanted: Quad ESL-63 Speakers serial # 13009 & 13010
so now for the bad news. In 2007 when we sold our house in Maryland I
stupidly trusted Earle's Moving & Storage in Annapolis, an Allied Van Lines
agent to look after a few boxes while we were getting our house in Florida
ready. When the shipment arrived later that year, the speakers were gone
along with one of our sofa's and a bunch of other stuff! Needless to say
Earle and his cohorts are now no longer in business and I know exactly why.
Apart from not understanding their own mission statement they didn't know
how to count boxes. On top of that, the Allied Van Lines claim service
actually had the audacity to tell me that it was my fault for not checking
through all the boxes on the day they arrived! What all of them?? I
have to say though, it was so
funny to be able to refer the claims agent to this web page that contained
copies of all the receipts and the entire history of the speakers including
pictures of them in the house where they were shipped from just five seconds
after she smugly asked to see the receipt for a pair of 25 year old speakers!
Just look at that check to the right. $5000.00 of that is for the now
famous Quad ESL-63's serial numbers 13009 & 13010. I guess they just don't
know that Quad ESL-63's go for about $1300 to $1600 a pair on eBay... But
like I said to the claims agent, I don't want the money, I want my speakers
back! If you know where these speakers are and can return them to me in
their original condition as of 2007, some of that $5000 will be yours!
Please let me know if you see them!
I did try a replacement pair of ESL-63's from eBay, serial numbers 13518 & 13518
but they just weren't the same as my original ones. The protection
circuits seemed to be cutting out all the time and I just didn't feel like
messing around with them, so I sold
them. I did use them though as a reference for setting up my
Technics SB-M1's that I now have to use as
the main stereo pair as my beloved Quad's are gone and that was very helpful.
If they were still here or ever come back, the Quad ESL-63's will once again
become my main
front stereo speakers and form part of the
home theatre system that has grown
around them over that time. Originally I had the
Technics SE-A5 to power them back in 1983
and they were used together for more than ten years. In 1994 when I needed
more amplifier channels for the home theatre, I built a
Velleman K4040 vacuum tube amplifier to use with the ESL-63's so that the
Technics SE-A5 could be used with the
center system. Tube amps are almost as unusual as electrostatic speakers
and they have been working perfectly together for the last ten years! See
my K4000 page for more usage details with
the ESL-63 speakers.
Pictures and Reference
Unfortunately I have found it difficult to get any really good pictures of the
ESL-63 speakers in their current setting because I have quite a coarse grill
cloth (sock) on them to maintain sound quality. The flash from the camera goes right
through the cloth and then reflects on the dust cover and the diaphragm making
them look nothing like they actually are! The picture on the top right
below is the only one taken with the flash on.