Gary decided to take the plunge and order a set of ESL IV’s for his apartment home after listening to a friends E R Audio Acorns and then auditioning them at our premises.

The following is his story but it doesn’t finish here.

Gary was so impressed with the sound and the build quality of the enclosures made by his son-in-law, a master craftsman cabinet maker, he decided to make the cabinets available as a completely finished loudspeaker.
The panels and electronics are built and tested by us, then shipped to Gary for installation into the enclosure, in the timber of your choice and finished to your specification.

But first Gary’s story, the following is a review received by us a couple of days ago.

My ESL IV Story and Review

I had been very familiar with Rob’s ESL designs for some years having listened to them on a few occasions in Rob’s listening/demo room and having listened many times to my friends Acorns.

Having run efficient near full range electrostatic/hybrids for the past 20 years, always through relatively low powered (18W/Channel) Class A Single Ended valve amps, I was very familiar with the ESL sound. The idea though of running full range ESL’s was therefore of huge appeal. However, being a committed apartment dweller, and not having the luxury of a dedicated listening room I just did not have the space to host the large Acorn’s. Also, NO WAY would they pass the all important WAF (Wife Acceptance Factor) in our space.

Then on a visit to Rob’s late 2018 I got to hear a single ESL IV (2 panel) prototype. In a word WOW!  Size: perfect, Sound: fast, dynamic, accurate to source and Low end frequency response in the low 30’s. I was hooked!  Earlier this year it was back to Rob’s with some familiar CD’s for a listen to a stereo pair and the above was reinforced coupled with excellent soundstage width and depth. And, again, excellent bass response well into the very low 30’s on source material I know very well. For me bass MUST keep pace, clearly define the beat, clearly add to the harmonic content and most importantly not blur it.

The jury was out on my 18W Class A SE valve amp (a never to be sold no longer produced work of art) being able to drive the ESL IV’s to suitable levels, However I did listen on Robs 20W Valve/FET hybrid with excellent results. As it turned out I need not have worried. On that basis money exchanged hands soon after and Rob delivered my ESL IV kits to Brisbane on time about a month later.

Back at home armed with the construction manual my son-in-law who is a Master Cabinet Maker and I began design and pro-typing the enclosures. This process took much longer than expected with multiple iterations developed and pro-typed over a 4-month period until we felt the design was right in terms of aesthetics (WAF), quality of build and build efficiency. We developed the necessary jigs to streamline the build so we could produce the speakers in different finishes and timbers on demand. 

It was essential to marry amazing sound with the look and feel of fine hand-crafted furniture.

Final assembly of the ESL panels and transformer units into the enclosures was relatively straight forward. A good soldering iron and solder, long nose pliers, wire stripper or cutters, digital multi-meter, screw drivers and a LED Magnifying lamp with third hand is very useful when attaching the wires to the connectors. Final assembly including testing took us approximately 6 hrs.

Well, they are complete and have been installed in our lounge and operating for a couple of weeks. To friends and family who have seen and listened, they are delivering truly spectacular sound and look as intended,

Our observations in general HiFi audio speak:

Lightning Fast: My Wife and I have never heard more realistic sounding Brass.

True to Source: Male and Female voice are in a word “BEAUTIFUL”

Imaging & Sound Stage: Accurate and holographic (both in width and depth perception in particular. Can be surreal on live material with instrument positions well defined and lead singers in centre and well out in front

 The All-Important Bass: Right-proper Bass is the weak link in any electrostatic, hence the rise of the hybrids and or the use of subs. NOT so here. The ESL IV’s go LOW (the entire panel handles bass). The Bass doesn’t hit you in the chest owing the huge surface area of the panels and the movement of the membrane.  But, because of that huge panel area bass is deep, fast, well defined with amazing separation between different drums and bass instruments INCLUDING electronic bass. My phone app advanced spectrum analyser showed -6db output at 28hz (seated) so normal acoustic drum sets, bass guitar, double bass are handled superbly well. It is there when it should be! As it is a single panel “shared” by all frequencies there are no phase issues between driver’s so they keep the beat. Toe-Tapping I would call it!

Comparisons:  I have a number of speaker systems (I never sell any) in my personal arsenal from large hybrid ribbons and hybrid electrostatics and small book shelf speakers that all qualify as “Hi-End”. I have also listened at length to other electrostatics/hybrids including Robs other designs, Quads, Martin Logan’s. Cadence (I own Amaya’s).

Put simply, for all the reasons stated above: for my wife and I on our ever continuing journey to audio nirvana our personal verdict the ESL IV’s are a significant step change in Audio Enjoyment, and they don’t look half bad either.

 One last thing on Amplifier Compatibility: My existing ESL’s are 91db efficient. Running them through my 18W Class A SE valve amp is a doddle. Our max loudness point in the apartment (it is fully sound proofed) is about 10 o’clock on the volume control and it is “pumping”. Running the ESL IV’s required an extra notch (11 o’clock) for the same max level we ever listen too. i.e. well away from clipping. So I’m guessing the ESL IV’s run in the high 80db’s in terms of efficiency.

I have no idea as to frequency/impedance and phase/capacitance implications but they do not seem to phase my amp. (excuse the pun)

So any good quality 25+ watter would be a safe bet as a starting point. I also have a 50W Class A SE valve amp running big 805’s down in the garage. It is physically to big for the apartment, but I am going to give it a run just to see!


Note from Rob, ESL IV or Acorn??

We are often asked, which is the better speaker, the ESL IV or the Acorn. The main difference between the 2 speakers is the way they deal with the input signal. The ESL IV uses a resistive transmission line to compensate for front to rear cancellation effects and equalise the output. Good horizontal dispersion is created by the very narrow treble section in the centre of the panel. The Acorn uses separate sections driven by separate transformers and a high quality crossover to achieve the same result. Again, good horizontal dispersion is created by the narrow treble section set on the inner edge of the loudspeaker.
Both speakers have a very similar sonic footprint with excellent detail retrieval, however, the Acorn is 600mm taller than the ESL IV giving more output area and a longer line source making it more suitable for larger rooms.

Pro’s and Cons.

Both loudspeakers have excellent sonic performance. The ESL IV has excellent bass response because all of the panel area is used to reproduce low frequencies. On the other hand, to achieve similar bass the Acorn requires 2 large bass panels per side and dedicated transformers with a higher turns ratio.

Both loudspeakers deliver exceptionally clean and clear sound with very little evidence of audible distortion.

The levels of IMD (Intermodulation Distortion) are very low from both the ESL IV and from the Acorn electrostatics. However, the ESL IV uses a single large diaphragm to produce the full range of audio signal. Depending on how hard they are being driven the diaphragm excursion to reproduce say 40Hz is quite large. While the diaphragm is moving to reproduce the 40 Hz signal it is also required to reproduce higher frequencies at the same time with the potential to create IMD. All wide range speakers suffer the same issue, some more than others. We have taken care to minimise this effect but cannot eradicate it.

The Acorn operates differently. The Acorn has dedicated bass, mid-range, treble and super treble sections, driving their own diaphragm. This means that the bass section is only required to reproduce frequencies up to 260 Hz, the mid-range from 260 Hz to 6 kHz, the treble from 6 kHz to 18 kHz and the super tweeter strip from 18 kHz to 35 kHz. Because the treble section does not have high excursion even when driven hard, the super treble strip can share the same diaphragm without a problem.

This does add to the complexity of the speaker, requires 3 different transformers and a high quality crossover. However, and don’t forget I am strongly biased!, in my view the gain is worth the pain.

The downside is higher cost!! At this level of sound reproduction we are on the almost vertical trace of the law of diminishing returns, small improvements don’t come cheaply.

ESL IV Review and enclosure details

20191010_065536 (1)

The photographs below are of Gary’s ESL IV’s in his apartment, our apologies for the Moire Effect seen on the front stators, they don’t have this appearance in real life. This is caused by the array of acoustic slots on the front stator being superimposed over the slots on the rear stator.
The front grille cloth has been removed for best quality listening, this is normally in place when the speakers are silent. Grille cloth prevents dust and insects getting into the works and should be used.

The timber used in the enclosures below is Cherry, the finish is satin polyurethane, high quality WBT connectors for speaker cables have been used.

As mentioned earlier, Gary and his son in law Scott will be providing a custom build service
for enclosures to suit the ESL IV. They have made jigs that will allow the design above to be reproduced accurately and consistently with an exceptionally high quality finish, the timber and finish used is your choice.

The service offered by Gary is for the enclosures to be manufactured by them and the fully assembled panels and electronics to be installed so that you will be supplied with a tested, ready to use loudspeaker.

Prices will depend upon choice of timber and finish so is POA. Gary can be contacted on the following number Gary Young: Mb +61-488003221.

Gary will also extend this service shortly to include the 505 ESL and the Acorn loudspeakers.



Fine Audiophile Equipment

Designers and Manufacturers of Electrostatic Loudspeakers and Fine Audiophile Equipment

E R Audio Pty Ltd. ACN: 120 797 775, ABN 48 120 797 775


© Copyright E R Audio 2002-2018 Legal Website designed by RNM

E R Audio Home
Gary's ESL IV