Sunday morning February 9th, 2020 at my home in Wickenburg ,Arizona ;

Mr. Adrian Retamoza { 44 years old } and Mr. Adam Skipper { 52 years old } did a comparative Audition of three ESL Speakers ; The  ER Audio ESL IV, the Quad "57", the Quad "63".  Both men are devoted Audiophiles who have had many years of experience on listening to sophisticated Sound Systems.   Between them ; they have  owned and listened to music systems  such as Shindo, Nagra, Quad, Altec, Audio Research, Audio Note Japan, Leben, Mary Anne, Auditorium 23, Klipsch, Voxativ, Lowther ,Martin Logan  and even  custom Single ended amplifiers by Gordon Rankin.  Their  experience in this field is comprehensive.  
They are both "well to do" professional men in excellent health with good hearing.   The speakers were set up parallel to each other ....placed several feet from the back wall in  a large rectangular  room with good acoustics { full  carpeting, furniture, and no large flat " live " reflective surfaces }. The program material was a high quality CD played on an Esoteric CD 1 cd transport, a Schiit Yddrasil  DAC, and a Audio Note M7 " Silver " preamplifier.  Two different amplifiers were employed.  A 25 watt. Redford Revival STA 25 , with gold Lion  EL 34 output tubes , and a Nagra 300 push pull 300b amp , equipped with a pair of Western Electric 1988 Re Issue 300b tubes.  
All interconnects were  Audio Note silver.  The speaker wire was simple 12 gauge stranded oxygen free copper with gold plated banana connectors.  All electronics were connected to an  isolation  transformer  to avoid any line interference. The CD used for the comparison was the very well recorded  Diana Krall  ,"Live in Paris". This recording is considered one of her best, and  the piano and voice passages are a good test of the different speaker's comparative merits.  

The  Quad 63  connected to the Radford amp presented a thoroughly musical and accurate picture.  The sound stage was not very broad { stereo recording into mono not withstanding }.  The detail retrieval was peerless although the  music seemed to come from  a space a bit back from the speaker.  It was a wonderful experience to listen to music portrayed  with such  accuracy and ease of listening.  If no comparisons were ever made to the other two ; the Quad 63 speaker would be a most satisfying speaker.  The next speaker was the ER " 4 " (ESL IV - Rob).   This speaker is much more efficient than the Quad "63".  The pre-amp sound level had to be turned down from the setting for the  " 63".  The ER Has a much more dynamic and punchy presentation.  It seemed to be  more dynamic, with  more sound pressure though the accuracy and tone of the bass instruments was identical.   Diana  Krall's vocals were clearly presented and quite human sounding, and though she did not stand out, the music presentation was in front of the speaker.  The  sound stage {a bit narrow} was  the same as the Quad 63.  Where the  63 had the music coming from in back of the speaker....the ER had  the music  in a much, much more up front presentation.  Switching from one speaker to the next made this assessment an accurate appraisal.  Listening to  either without focusing on these aspects   { like being in another room or facing away from the speakers}  " then" the music sounded exactly the same as far as tone, balance  and accuracy  from either speaker was concerned.   When  we switched to the Quad 57.......we needed to turn the volume control " much "lower to compensate for the apparently greater efficiency of the  " 57".  The bass response  { though not as forceful and forward as the ER}; was pitch perfect , detailed and adequate in the room.    The vocals played through the Quad " 57" were noticeably more realistic and human.  This is not to say the others were not musical and enjoyable...just that when switching from the others to the 57...the pleasure of listening  to the Quad "57" increased,  Diana Krall seemed to come closer  and sounded more intimate.  The sound-stage of the 57 was significantly broader and more enveloping than that of  the other two speakers.   I am aware of several  reports { over the years } that criticise the Quad 57 for having a narrow " sweet spot " where listeners must position themselves to hear all the music.  The judgement of the three men listening to these speakers in comparison to each other belies those inaccurate criticisms.   The Quad 57 out shone both the Quad 63 and the remarkable ER "4 " in all areas regarding listenability and musicality.  As I stated before....the differences would probably not even be noted. Unless a side by side comparison was conducted.  

Next step was to  drive the speakers with  the expensive Nagra 300 push pull amplifier using Western Electric "Re Issue" 300b tubes.  Perhaps one needs a vivid imagination to detect any differences in the amplifiers.  The Nagra was  "perfect"; but the Radford Revival STA 25 sounded more musical to all three listeners. Having owned an original Audio Note Ongaku for many  years ; my experience was that it too was a  " perfect " amplifier but other amplifiers were more musical.  
The Nagra amplifier did not have the synergy with the Electrostatic speakers that the Radford Revival had.  This is not a review of the Radford Amplifier ; but any reader of this essay might be advised to  investigate the remarkable qualities of the Radford STA25 .    An amplifier that sells for twenty percent of a Hallmark product like Nagra....and is more musical with ESL speakers a gift.  
Speaking of gifts ; the ER Audio "4" Electrostatic speaker is a gift as well. Compared to the Quad ESL 63.....which if rebuilt would cost over $3,000 (this is the cost to rebuild existing speakers - Rob).     The ER is a Bargain at a cost of approximately $ 3,500.

The latest iteration of the Quad 63 is their 2900 series.  These are essentially identical versions of the " 63"  which now sell for over ten thousand (US) dollars . They are made in China....and still suffer from problems with the problematic adhesives used in their construction.  Rebuilt Quad 63's from a  rebuilder like Sheldon Stokes with top quality adhesives and electronics might be a good way to enjoy  music; but the ER  "4" with advanced mylar panels and superior electronics , as well as a more forward musical presentation is the real bargain for music lovers.

A frame for the ER panels must be fabricated ; but his kit is easy to assemble . For the money; the ER "4" is the sensible choice.  A rebuilt Quad 57 would entail obtaining a serviceable pair of old units then finding a competent rebuilder.  Sheldon Stokes as well also rebuilds the 57.   Both  the owner of ER Audio and Mr. Stokes caution people about rebuilding Quad 57 ESL speakers since these half century old units are fragile.   While we were doing the comparisons ; I connected my  old { never rebuilt} Quad 57 ESL.  This  speaker had some electrical repairs  and updates but the panels were original and never touched.    Because of its age.....the panel's  diaphragm required a full day to re charge.  When the original  speakers were compared to the recently rebuilt 57s used for the comparisons....They actually dominated the listening room with an even more musical and accurate presentation of the program material.   Please keep in mind.....If any of these speakers were "not" subject to comparison to each other; but were compared to the bulk of hi fi speakers on the market today ....they would totally dominate the listening room.   In order of musicality; Quad "57" first...ER ESL second with the Quad 63  a close third.   On a value basis....the ER"4" is the hand down winner.    

Francis m reps....designer and manufacturer of the Reps " R-1" Drive Unit

Addendum to Comparative listening tests of the three ESL speakers.

All three men noted that the  ER "4"  was in the middle ranking in their listening preferences. They cited the Quad "57's" delightful {comparative } musicality as their reason for choosing  it over the " state of the art"  ER "4" and also  the more modern later iteration Quad "63". We also pointed out that the differences in detail retrieval in all three were not "significantly" great. The Radford STA amplifier was also noted for it's musical character over the  very refined and expensive Nagra 300amp. Subjective analysis is essentially a matter of personal preference. Comparative analysis between these three unbelievably accurate a side by side comparison is something like asking which particular flavor of custom-made; small batch " ice cream" a person prefers. In a nutshell,  although human voices from the Quad "57" seemed mellow to our ears, in absolute terms; the superb detail retrieval of the ER "4" superseded both of the Quad speakers. The actual measured specifications of the Nagra surpass the Radford even though the Radford was our preferred amp.  Standing alone.....any of these ESL's is a giant among all those Pygmies being sold  in the Speaker World.    The fact that ER  Speakers  are available at such reasonable prices is the real gift to music lovers.     f reps



Note from Rob - E R Audio

Before you delve deeply into Frank’s report there are a couple of things that need to be made clear.

The comparison between the 3 ESL’s was conducted in mono with the stereo signal combined from left and right channels feeding a single loudspeaker. While a good mono recording can give depth, width and sometimes height, the sound-stage and instrument placement will not be as intended by the audio engineer that mixed the track, this requires stereo to reproduce.
Equally, any spatial enhancement techniques that rely on time domain / phase differences between stereo speakers will not be reproduced properly (or at all!), an example would be Q Sound recordings. The ability to resolve this type of recording gives an insight as to the phase accuracy (or inaccuracy) of the speakers being auditioned.

In my view, both of these attributes are important when auditioning speakers and can be the deciding factor when making a purchase.

The comments about the dispersion characteristics of the Quad 57 (again, in my view) are not accurate as the speaker was listened to in mono. While you can get a reasonable subjective idea of the width of high frequency dispersion in mono, to really determine whether the “sweet spot” is narrow or wide you need to be listening in stereo.

After writing the review below, Frank and his friends had time to discuss the outcome and added a few extra comments in an addendum.

Many thanks to Frank and his friends for going to the trouble of the comparison and subsequent review.

The photograph below shows the arrangement of the single speaker under review.

ESL IV review

E R Audio ESL IV versus the highly regarded Quad 63 and Quad 57.

Review conducted by Frank and a couple of audiophile friends.

Hi Rob

I have for a while been thinking of adding an update to my write up on the IV’s as I have now been living with them for over a year. I still find them quite addictive and hard to tear myself away from a listening session.

I read the curious review by Frank and Co. I don’t see how a meaningful evaluation can be made by listening to a stereo source through one speaker? I have found my IV’s to have an amazingly wide and accurate sound stage, even a bit startling at first. This has to be down to the controlled HF dispersion and the reduced muddling reflections, something that cannot be appreciated by listening to a single speaker.



Hi Geoff,

My view entirely. However, all speakers compared were listened to under the same conditions using the same amplification etc so it's valid to note any differences between them. Clearly the soundstage (engineered into the recording) cannot be reproduced as the engineer intended and, in my view, this is one of the more important aspects of a speakers ability, to accurately reproduce the soundstage as intended without any other artifacts to spoil the performance. Equally, the width of the sweet spot (as I noted prior to Frank's evaluation) can only be determined in stereo, another very important aspect of reproduction.

I raised all this with Frank and he has arranged to set them up in a different location where they have a bit more room for a stereo comparison.

At the end of the day I'm reasonably happy with the outcome, being classed alongside these 2 speakers is not all bad! However, I know the ESL IV is a better all round performer than either of the Quad speakers but the mid-range of the Q57 is very difficult to beat, hence the accolades it has over the decades. This tends to make the Q57 suitable for a certain type of music rather than being even handed across all genres.

Having said that, the ESL IV has far better bass and treble performance than the Q57, this did not really come across in the comparison. The Q63 is a very good speaker in it's own right but it's a bit too polite and sounds rather like it has an old army blanket draped over it (at least to mine and many others ears) and it's no surprise it came out third.

I think the main thing to consider here is the performance level that is being compared. All of the speakers are very capable, and while each has its own shortcomings, the overall level of performance is exceptionally high, certainly of a level that most box loudspeakers cannot achieve, regardless of cost. This brings Frank's comment about value for money into perspective.

In Australia, a set of the latest 4 panel Quads equivalent to the Quad 63 (the Quad 2812) will set you back between $15k and $18k. A new set of Quad 57's (not old ones rebuilt) made by Quad Germany is about $13.5k plus shipping to Australia so is around the same price as the Q 2812.

The ESL IV in fully assembled form is just under $4k but requires cabinets to be made that can cost as little as a few hundred dollars to several thousand depending on materials etc.

Any further comments you wish to make will be welcome, especially those that are favourable!!


E R Audio Pty Ltd

Rob’s Response

Having read the review carried out by Frank and his friends, Geoff sent us the following comments. If you have anything to add on this subject please feel free to email us on and we will publish it.
Please be aware that we will not publish anything that is considered to be irrelevant or unsuitable for this blog.

Grant’s Comments

Hi Rob,

 regarding this page, where you welcomed further comments, , where you say, “...the mid-range of the Q57 is very difficult to beat, hence the accolades it has over the decades.”

My comment is that I am always suspicious when a speaker that is somewhat lacking in some frequency ranges, gets accolades in the range where it is stronger in output and smoothness, like the Q57 mids in the comment above. It is precisely the (relative) absence of the other frequencies that gives this impression, due to the lack of masking by other frequencies. As soon as the other frequencies are added back in, to make the music have the right sonic balance that it needs for realistic playback, the ‘special’ midrange is no more.

 My point being, the ESL IV midrange might be equalling or bettering the Q57 midrange, but it isn’t ‘standing out’ and is instead appropriately immersed into the totality of the music, as was hopefully intended by the players and producers.



Rob’s Response

Hi Grant,

 It’s good to hear from you again.

 I couldn’t agree more. The Q57 does have issues at both ends of the acoustic spectrum and because of this the mid-range is emphasised. However, the mid-range you get is excellent, very smooth and refined. This doesn’t mean it cannot be equalled or bettered, particularly as materials and techniques improve.

 The Quad 57 can still hold it’s head high in modern company but its limitations are now very obvious. Low frequencies need supplementing, particularly in larger rooms, so a good quality dipole woofer or sub-woofer is required. Likewise, the HF is wanting and can be improved by adding a dipole high frequency transducer, preferably ESL based. This is quite difficult to do with an existing 57 but can be done when panels are stacked.

 The thing that is rarely mentioned in reviews is the beamy nature of the 57. In the sweet spot it is excellent, but, move your head about 30cm to one side and the image collapses. In my view (and I may be wrong!) the full performance of the speaker should be able to be shared by at least 2 people or preferably three seated in front of it. In our own products, we go to a lot of trouble to maintain the stereo image as far off axis you can get in a given room.



Keep the comments coming - Rob.

As an addendum to the above, it must be said that the Q57 is quite sensitive to the shape of the room and placement within it. As with most loudspeakers, the room has a marked impact on the perceived sound so objective results will vary from room to room.

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