December 2013 issue


World mail  November 2013 issue


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Your experts are -
Noel Keywood, publisher; PR Paul Rigby, reviewer; TB Tony Bolton, reviewer; RT Rafael Todes, reviewer (Allegri String Quartet);  DC Dave Cawley, Sound Hi-Fi, World Design, etc.



Astell&Kern AK120 portable player drives headphones or the hi-fi, playing

top quality digital, as well as MP3, AAC from iTunes and CD rips.




I enjoyed your review of the Astell&Kern portable digital player AK120 and the riposte from two readers in the next magazine. You have to do a review with other contenders and iBasso DX100 has to be in there! It has a full size headphone socket, does that signify bigger output? 

I borrowed an AK120 and was very impressed both through PX100 headphones and my Almarro amp and Tannoy Prestige speakers. 

Just two small things that concern me. I had to play most at 72 volume (max 75), through PX100s. I know the latest AK120 goes to 150 volume. Is it  is louder? 

Second point. Will the cost of downloads come down? £12.00 is not that much to pay, but it is if you want lots of good downloads. 

Please try and dem. the iBasso DX100, it does look cool, but does it sound cool?  

Thanks for a great read, 


Leeds – up north!


Hi Robert. We have been trying to get HiFiMan and iBasso players for review, to bring us up to date on the high-resolution portable player front. No response from HiFiMan but perhaps they know that their HM-601 player is too big and heavy to compete with the more modern iRiver players. We reviewed the Colorfly player in our October 2013 issue and it was also too large to be a true portable. 

We’ve had more luck with iBasso however, their new DX50 being reviewed in this issue. With a weight of 150gms, and dimensions of 64mm wide, 100mm high and just 17mm deep it is almost as small as an AK100/120. It has a high-level analogue line output too, so it can be used to drive a hi-fi system, much like a CD player. There is a digital output, and of course a headphone output. 

Output from the AK120 remains 1.5V,  Astell&Kern state.

Will the cost of downloads come down? Unlikely I would have thought. Speculating, iTunes may well offer single tracks at 24/96 in the future and this would be easier on the pocket perhaps.

I’m a complete convert to my AK120 player. It’s replaced CD, even though it plays (ripped) CD, and it plays high-quality digital, as well as transcribed analogue. It can drive headphones or a hi-fi. Portable hi-res players really are a move ahead. NK



My gripe is with Noel’s review of the Colorfly C4 Pro, unceremoniously downgraded to the ranks of ‘MP3 player’ on the front cover. How different would this have read I wonder if you had actually reviewed it when it first appeared some three years ago? As an offshore worker who likes his ‘sounds’ and who has constantly had to deal with limited baggage weights I have invested in numerous portable devices in the past. 

I progressed from the Sony Walkman Pro (WM-D6C) to the Colorfly C4 Pro, purchasing one soon after it first made an appearance. What a revelation, the sound quality available from this device is quite amazing, even more so when used as a source in my home set-up, and I agree wholeheartedly with this aspect of Noel’s review. 

Judgement, I feel, has been somewhat clouded by the much later release of the Astell&Kern machines, in particular the AK120. I can only disagree with much of Noel’s conclusion. I love the look (and those ‘faux graphics’ are in fact laser-etched artwork), pull it out and it becomes a talking point rather than another bland-looking box that appears to be some sort of mobile phone. I’ve yet to have anyone collapse laughing when they have seen it. 

Limited it may now be in the file format section but it was perfectly adequate when it was first marketed (long before the availability of DSD downloads or even 24/192 FLAC files). I find WAV files perfectly adequate, especially when combined with a pair of AKG K451 headphones. Build quality is superb even if it’s appearance is not to one’s liking and I am sure I will get many more years use out of this amazing device. 

Whilst I understand that things become more sophisticated over the years I feel that Noel’s review can only have damaged the marketability of a device that is still in production and, as such, should not ultimately have been published. Oh, and as for portability anything I can get in my hand baggage and will fit in my work-shirt’s pocket I’d deem portable.

Alan Strudwick



Colorfly C4 Pro. "What a revelation" says Alan Strudwick. "The

sound quality available from this device is quite amazing, even

more so when used as a source in my home set-up".



Thanks for your user experience Alan. I don’t think many readers will agree that we should not publish critical reviews because they harm a product. Our reviews are more frank than deprecating, highlighting both weaknesses and strengths so potential purchasers can make up their own minds, on the basis of expert advice. In particular, our ability to measure these high resolution players is showing good correlation between their EIAJ Dynamic Range value and sound quality – and there are big differences between them. These are facts worth revealing and they show how the later Astell&Kerns are superior to earlier designs like the Colorfly C4 Pro.

Digital technology moves fast these days and the eccentric Colorfly C4 Pro looked archaic to all of us at Hi-Fi World. I suspect it was designed to appeal to the U.S. market, but I’m not sure America would warm to its style. But hey-ho, this is a matter of taste and I guess it has its own cast-iron charm. If weight is an issue then there are smaller and lighter players available now, but the C4 Pro did have a ballsy sound; I enjoyed this part of it.

The C4 Pro is inevitably lagging behind later arrivals from iBasso (DX50, in this issue) and – in my hands being reviewed at this very moment – the FiiO X3. But for the time being at least the more expensive Korean Astell&Kerns (AK100 £600; AK120 £1100) have a clear advantage in sound quality over the Chinese players. 

A game changer will surely be the low price of the iBasso and FiiO players though; this alters the picture substantially. They cost less than half that of the Colorfly and AKs. 

Also, portable players that can play when connected to a mains power supply, rather than just recharge from it, can be used as domestic hi-res players, successors to CD players in effect. They can be connected through their headphone or line outputs to a hi-fi amplifier, or for better sound connected up digitally to a DAC, A/V receiver or ‘digital’ amplifier. I hooked up the iBasso DX50 to an Audiolab Q-DAC and was taken aback by the improvement in sound quality – readily apparent over headphones. The X3 similarly benefitted, showing that these players are limited by their DACs/output amps, but can usefully be improved by feeding a high-quality external DAC.

Finally, puzzling why Sony recently released a high-resolution portable player that has no digital output, it was suggested to me by someone in the industry that this is probably to discourage digital copying and was likely a requirement forced upon Sony Consumer by Sony Music. Is that why high resolution players come only from China and Korea? Is there pressure not to produce them? 

Since high-resolution downloads are not copyright protected and can be duplicated and re-distributed freely, irrespective of such players, this would seem not to make a lot of sense, but with copyright protected Blu-ray going nowhere and the future appearing to lie in unprotected downloads, there may well be tensions and politics behind the distribution and playback of such players. NK



I have bought a Terratec Xfire 8 from Germany via Amazon for £77 and I left a mini-review on Amazon (as AudioNut), as below.

‘’ I have just used this unit to record a vinyl LP using my Rega RP1 and Rega Fono pre-amp into my PC via USB and Audacity (free online software) at 192 kHz sampling rate and 24 bit high-definition quality, exported as both WAV and FLAC. All the cables I needed were in the box and the result was amazing. The recording is as good as the LP even when played back on a Naim Superuniti and Quad electrostatic speakers.

I did have to reboot the PC several times when installing the Terratec drivers and software but it was all up and running in half an hour. All the required cables come with the unit. I suggest downloading the manual and drivers from Terratec before starting the installation. Read the manual before you start – the driver software is clunky but OK once you learn to double click on icons to obtain a list of actions to set up the drivers for each input and output..

The unit is beautifully made and encased in aluminium – like a piece of jewellery – and the sound quality is superb for the price.

The unit has a two year guarantee. It took just four days to arrive from Germany via Amazon. It fits in the palm of your hand and is powered by the USB connection so you can carry it around with a laptop easily. It records from line or microphone so it could be a portable twin track recording studio with a microphone and laptop but I only used it for recording LPs. It comes with ASIO drivers for low latency recording. It outputs audio in stereo via gold-plated phono plugs, or surround sound via mini jack plugs, to connect a laptop or PC to a hi-fi or AV system. It has a headphone output, with volume control, and also comes with cables for digital audio connection. Highly recommended and superb value for money".

I hope you and Rafael Todes will review this audiophile bargain.

Best wishes,

Mike Tartaglia Kershaw



Another way to record LP, the Terratec Xfire 8, Mike Tartaglia Kershaw tells us.





I wonder if you can help me improve the neutrality of my system, which presently consists of an AH! Njoe Tjoeb CD player (with all the upgrades), connected to a Conrad Johnson PV14 pre-amplifier feeding into an Audiolab 8000X7 power amplifier that Tri-amplifies a pair of Monitor Audio GR60 speakers. I am finding that as my tastes in music have become more diverse the system is sounding a little bright in the upper mid-range and the treble, most likely the product of the Monitor Audio GR60s' metal drivers. I am considering changing the speakers to either PMC OB1i or PMC PB1i but I don’t know which will produce similar levels of bass extension as the Monitor Audios and be sufficient to fill my living room. If the solution is to change some of the amplification I’m prepared to do that but unless it is completely unavoidable, I want to hang on to the CD player. 

Best regards,






To replace Monitor Audio GR60s, try audiotionining PMC PB1s, says Jon Myles




Quad QMP mono power amplifiers are powerful but smooth, and would

suit Monitor Audio GR60s.




Hi Jon. You don’t say how large your room is but as you are using GR60s I’ll assume it is a largish space. In which case, as you suggest, you have two options. The Monitor Audios do have good, deep bass and are very clean and fast – but, yes, those metal drivers can make them sound a tad bright to some 

ears. PMC’s transmission line loading helps produce prodigious and tangible bass from a relatively small enclosure – but to match the GR60s I’d suggest you would be looking at the PB1is.

However, my personal opinion would be to look at the amplification. The Audiolab 8000X7 is (at its name suggests) a seven-channel power amplifier rather more directed to AV duties than pure music reproduction. Therefore I’d look at changing the amplification first. In which case you have a rather wide field to choose from – depending on your budget and taste in music.

My thoughts, with the Conrad Johnson pre-amp, would be to go towards a Naim NAP 250. which sounds superb with a valve preamp.

Alternatively, Quad’s new QMP power amplifiers are very smooth and detailed and would definitely tame the GR60s top end.

Even though you won’t be able to tri-amp from either of these, I think you’ll find the better amplifier stage will make a very real difference to the sound. JM



I noticed that you reviewed the low cost Olympus digital recorders in a recent issue. Could I suggest that you also try to get hold of a Sony PCM M-10 as a comparison. I recently bought one to be able to make recordings from the radio (Troughline of course) to listen to the following morning and to make 96kHz/24bit recordings of some of my vinyl.

I found the sound quality of the Sony to be excellent for the money (I couldn’t justify the expense of an Astell&Kern) and play it through a pair of Koss KSC-75s which are ridiculously good for the amount I paid for them (£14). The Sony has a proper line out which contributes to its excellent sound (in my opinion).

Ergonomically it isn’t the slickest thing to use but I have formatted a Sandisk 64Gb MicroSD card to FAT32 format (see this link ) and now I leave this in at all times and just connect using the USB lead and drag folders into the memory. I think many of your readers might be interested in such a piece of kit so would encourage you to see if Sony will let you review one.

Kind regards, 

Clive Walker




"Could I suggest that you try to get hold of a Sony PCM M-10" recorder,

says Clive Walker. "I found the sound quality to be excellent".



Thanks for the update Clive. There are so many different digital devices these days it is hard to keep up with them all. The Olympus units were a very interesting way of recording and good at it too, if a tad disappointing when reviewed critically. But this comes down to 24/96 expectations being unfulfilled; relative to their low, low price they worked wonderfully. I’m sure Sony will let us have an M-10 to review, as they are very co-operative. NK



How many times can any of us truly say that we love, beyond any measure of normality, a band or a singer? I love loads of bands and types of music, but only three artists would make me attain a higher plane altogether and truly spin me around. I’m referring to a once in a generation occurrence – and that is if you are fortunate. 

Well pop pickers, over the last year or so another (my third) band made it to the “feel faint, dizzy, excited” state of being, that is so rare. I’m almost 50 and by this score I may not even get to put another band on to my list. 

Please understand, we are talking about artists here that move beyond simply loving an individual or band or composer. it’s almost a god-like reverence. Well the band in question is Milk Music, and with the greatest respect I don’t expect everyone to jump up and say, “oh yes I know who they are” or of course “aren’t they great”. 

The best place to see and hear them is YouTube. Spend 10 minutes watching them live, some recordings being better than others and see if you feel what I feel. You may not. If not, why not (too many nots). Write in and suggest an iconic god-like musical experience of your own.

I’m positive the boss here at Hi-Fi World would welcome our musical highs, as personal and as varied as they would of course be. 

Oh – any news on The Beatles mono box set ? Bye the way, The Beatles don’t make my list of three. 

Keep Broadcasting, 

Neil Porter.



Milk Music – rated higher than the Beatles by Neil Porter.




Er – thanks for that Neil. Perhaps Milk Music will move the world. In the meantime, if readers want to write in with their faves, why not? There are great artists out there, unrecognised. 

We have no word on completion date for the Beatles mono box set yet from EMI as they work to ensure authentic mono reproduction. NK



I have a very old friend in England whose hobby is hi-fi. I recently visited him, and he is using ‘streamers’ as well as a pair of Voigt corner horns. He also has a decent record player – SME 20, MacIntosh amp and a pair of very good big Tannoy speakers. He likes to collect vintage gear. He has music in every room of his house. He likes to play his ripped tracks randomly, because then he hears music he has forgotten in his large collection. 

I can understand that, but why not make a list and then from time to time, be tempted by something you have not heard for ages, simply because you had forgotten it sounds so damn good? 

I am not a hobbyist but have built up what seems to me to be an excellent system over many years - Brinkmann Oasis turntable, Naim 180/202 with Flatcap 2, CD5X and a pair of Sonus faber original Cremonas with JPS Labs Superconductor + cables. 

I love to read the notes on the LPs and CDs I play. I am reassured by having hard copy of all my music, and contrary to Noel’s remarks in his column in the August issue, I simply cannot comprehend the value, the complexities and risks of magnetic storage and reproduction. Neither can I imagine listening to music much better than I can now, except that next year, budget permitting, I plan to redo all connecting and mains cables with JPS Labs, and replace the electronics with a Nagra CD player and preamp combined and their Mosfet power amplifier. 

I fully understand that I have been lucky and blessed to be able to indulge in such great gear, and that the magazine caters for all types of people and their budgets, but I really cannot believe that the current fashion for digital and the corresponding anonymity of music – everywhere, on tap, no sleeve notes, in the background, often small sampling rates – can be a healthy sign for the future.

When I listen to music I like to sit and enjoy the special occasion. I have been lucky to attend many great live concerts, and it is fun to relive the experience closely. It’s almost frightening to feel a full orchestra or an amazing band in our modest living room. Yes – ‘awesome’ in the real sense. 

The whole computer music and digital thing leaves me utterly bewildered. In terms of politics, we were lied to about CD when it came out. You can scratch an LP and it will still play, not so a CD. But they do sound great now, even Red Book stuff, and I am happy to mop up others’ secondhand discs from Amazon. But what if there is a sudden change in Earth’s magnetic field? What if all the hard drives and chips and whatever fail? I can still play music. 

All the best, 

Kingsley Flint 






"But what if there is a sudden change in Earth’s magnetic field?" asks 

Kingsley Flint (this happens every few hundred thousand years, Wikipedia says). 

"What if all the hard drives and chips and whatever fail? I can still play CD!"



Many people were unhappy about my August column dismissing CD – see the next letter. I was echoing what others have told me and what seems to be a common enough view, that LP is seen as a valuable historic source, whilst CD can be – and now commonly is – ripped to a storage drive (NAS) or such like, then put in the loft. 

But plenty of people still like to reach for a physical object in the comfort of their lounge, rather than faff around with computers, it seems. As you say, good modern recordings on CD are plenty good enough for most people and CD now costs little too. In all, that’s a good raft of strengths and at present whenever I go to a press reception it is CD that is played. High resolution digital hasn’t really sunk in yet! 

One point I need to make, especially with regard to classical instruments, is that 24-bit recordings made through a high-quality ADC sound creamy smooth and have deep, dark silences, as well as laser-etched imagery. Hi-res digital really is easier on the ear and more natural than CD and very much suits classical. There are benefits, even if survival of global magnetic events is not one of them. NK



Sorry Noel, but I still listen to CD and LP and even tapes. I don’t believe in computer-based music. It is only a fancy and nothing can replace a case or a sleeve with a booklet containing the lyrics, the recording studio, the engineers and of course the musicians – so I don’t see any interest in music downloaded to a computer.

Remi Balestie




Using your excellent magazine as a guide over the past 10 years or so, I have built up a well-balanced vinyl record playing system which I am very happy with. However I have run into a problem and need some help and advice, please.

The system is a ‘vintage’ one, consisting of a Garrard 301 on a Quadraspire wall shelf, a SME 3012 12” arm, a Naim NAC 32.5 preamp and matching HiCap, a Leak Stereo 20 (Classiqued!), Heybrook HB3 or HB1 ‘speakers (refurbed by Wilmslow) on Atacama stands 52cm high. The listening room is a minimally furnished medium size (60 cubic metres) with a square 5m x 5m carpeted floor plan (not ideal!). There are some Auralex pyramids from Studiospares on the walls. I am also using a superb Audio Technica AT-OC9ML/II cartridge.

The system works perfectly well with late 50s vinyl: Ray Charles, Miles Davis, Elvis, The Everlys, Patsy Cline and 60s material, e.g. Dylan, Stones, Beatles, Kinks, the Who etc. It is also good with acoustic material and jazz. 

Where it runs into problems however is when I try and listen to later 70s vinyl records especially English ‘prog’ and American rock or pressings from the 80s and 90s. The sound then frequently becomes rather swamped or dominated by bass, to the extent that it is often impossible to listen to comfortably. I also need to think about my neighbours as I live in a flat! 

I should add that I have nothing against bass – I play bass guitar in a band – but tend to enjoy listening to it more when it is subtle. The biggest disappointment is with newly reissued 180gm ‘cult classics’ from the 60s that frequently seem to have been engineered for a ‘modern’ bass heavy presentation. I much prefer the originals – warts and all.

A record dealer I was chatting to the other day listens to 78s on early one-box record players and says the sound from these is surprisingly good, powerful and well balanced. He suggests that recorded performances on vinyl need to be played with the technology that was available at the time to get the best from them. He thinks my system with the Garrard and the Leak amplification will always make 50s and 60s records sound good for this reason.

My question therefore is: do I need to build another system for use with bass-heavy material? Should I begin again with a Linn Sondek? Or can I introduce something into the current set-up which would reduce bass in this way? Would different ‘speakers do the trick?

I have experimented with room placement. I have experimented with preamps with tone controls but do not like them. For example the Quad 34, the Audiolab 8000C and the Audio Research SP3. The Naim preamp, with no tone controls, I hold in very high regard (superb PRAT amongst other things). I have also experimented with cartridges and find many of them just too bass heavy.

Stuart Dunbar-Dempsey 






The Leak Stereo 20 amplifier, owned by Stuart Dunbar-Dempsey 

 – a beautiful sound, but it has limited power and the output transformers

saturate quickly with subsonics from LP.


I suspect two problems here. The heavier bass cuts and re-equalised, re-issued LPs that, as you say, often have poor quality bass made more apparent, are putting too much low frequency information through the Leak’s not-so-big output transformers, causing them to saturate, something they will do at just a few Watts at very low frequencies. The cure here is to use a phono stage with a switchable warp filter, like an Avid Pulsare II. This will both lighten the bass and improve bass quality.

I suspect your Leak Stereo 20 is running out of puff driving Heybrooks. A more powerful valve amplifier with bigger output transformers will improve bass quality, but the room, being 5mx5m, will have a strong resonance around 34Hz and this may well remain a limiting factor. I suggest you try to get a home demo of alternative valve amps, if this isn’t sacrilege! NK




The Avid Pulsare II phono stage has a warp filter that eliminates subsonic

signals from LP. Designed to prevent loudspeaker cone flap, it also lessens

output transformer saturation in low power valve amplifiers.



After several conversations with you at various meetings I am saving up to upgrade my Sondek with an Ortofon Cadenza Bronze (this is the one, right?!) to enjoy my vinyl collection, and in the meantime I continue to enjoy my digital collection. I am lucky enough to own a dCS Puccini DAC/SACD player. Sometimes I feed it with files pulled from my server using a Linn Akurate/Kinsky system, and sometimes I send it files directly via USB from my computer/Windows/JRiver Media Centre 18 setup. 

I have always enjoyed the sound of SACD. I have a fair collection of SACD discs, both popular music (I am of the Floyd/Genesis/Yes generation) and classical. Generally I find I prefer listening to SACD discs compared with corresponding PCM files, even at high-resolution – 24/96 or 24/192. I am aware that others disagree. 




Teac's free DSD file player for Mac and PC can play .dff files and may

be just what is needed by Chris Corrigan to play Direct Stream Digital (DSD). 


Anyway, I thought I would listen to some native DSD downloads, by-passing the SACD disc. With the help of Rav from dCS, who kindly sent me the requisite firmware, I updated the Puccini to play native DSD (thanks Rav). I then went to the Channel Classics site run by Jared Sacks in the Netherlands. Jared collaborates with a number of excellent artists to produce high-quality recordings in both PCM and DSD. Jared is obviously dedicated to his art and to his artists. I downloaded Bach’s Mass in B Minor by the Netherlands Bach Society: an astounding work, beautifully performed in this recording and available to download in MP3, standard (16/44.1) and high-resolution PCM and DSD (.dff file) format, as well as an SACD disc. I couldn’t help noticing that the PCM files, even at high-resolution (24/96 or 24/192) and SACD discs on the site were considerably cheaper than DSD (.dff file) downloads. Jared explained that this reflects the greater technical complexity of making these files as well as the greater server capacity required to store them. Apparently, discs and downloads are also taxed differently. 

While I can quite see his points, if this is going to be a generalised phenomenon then it may set the cause of DSD downloading back. In addition, the single .dff file containing all of the album tracks was not tagged: I had to add artist/album tags and import the album artwork from elsewhere before JRiver recognised it: I couldn’t get it to show up on Kinsky at all. And finally, to the principal point of this letter: the JRiver player converts my .dff file to a 32-bit, 192 kHz PCM file before sending it to the Puccini, so I’m still not hearing the native DSD. I cannot seem to stop it from doing this. It does not appear to be able to “play” .dff files directly. I am sure that you clever people at Hi-Fi World know how to deal with this, and would be most grateful if you would let me know. 

Kind regards. 

Chris Corrigan




Bach’s Mass in B Minor by the Netherlands Bach Society.


Playing DSD is not a worked out process for computers, I found when reviewing Teac’s UD-501 DAC. In that case I used their own free software player that you can download from Sorry, I can’t guarantee success here and I would have thought dCS might know a thing or two about this difficult and fledgling topic. Also, see Blue Coast Records website for more info, as well as 2L site. Please let us all know how you get on. NK




I’ve read with great interest your recent discussions on the Quad ESL-57s. I am lucky enough to have a friend who owns a fully working, original pair used in conjunction with a vintage push-pull amplifier and I think that they are superb speakers. The only areas that I would criticise are the absence of sub bass (but the quality of bass makes most box loudspeakers sound broken) and the fact that they have a very small hot spot so are ideally suited to listening alone. Incidentally I can confirm to Rafael Todes that it is possible to get a very good feeling of layered depth from 57s but suspect that it requires very good quality output transformers and the right combination of valves upstream of these. Unfortunately both of these can be costly. 

My main reason for writing was to ask whether you can explain the reason for the very narrow hot spot of the speakers. I wondered whether it could be down to the flat nature of the treble panel. 

Alternatively, could it be due to beaming effects from the relative sizes of the bass and treble panels and the frequencies they operate at? 

I noticed that in the second review of the Martin Logan Electromotions you described that they also had quite a narrow hot spot, would you say this problem is inherent to electrostatic speakers? Do you know if anyone has ever measured the panels of ESL57s separately to see what contribution the bass and treble panels make? 





Founded in 1921, The Netherlands Bach Society is the oldest early music 

ensemble in the Netherlands, and possibly in the whole world, they say.



I would be interested to know what frequency the crossover works at and how steep the roll-off curves are. Is the hot spot effect caused at very high frequencies alone or at midrange frequencies? If the former is true then might it be possible to make a hybrid electrostatic with the very highest frequencies handled by a different device with better sound dispersion characteristics?

I did think about the Audax HD-3P as this has extremely low moving mass but unfortunately they are not made any more (although I do have a pair that were repaired by MOCA audio and can be re-pressurised as necessary). Alternatively ribbon tweeters are widely available but do these also suffer from limited dispersion? 

Kind regards, 

Clive Walker 








"Can you explain the reason for the very narrow hot spot of the Quad

ESL-57 speakers?" asks Clive Walker.



Dispersion of a Quad ESL-57. Go to

Quad ESL-57 to see more measurements on this classic loudspeaker.



The Audax HD-3P piezo electric tweeter leaked its gas and deflated over time.

They can be re-pressurised by Mocca of France says Clive Walker.


The limited horizontal dispersion of the ESL57 is not, necessarily, a characteristic of ESLs in general but can be found on many panel speakers. It is, in fact, quite possible to arrange an ESL that has wide dispersion but it does have to accord to a specific design. For example the current ESL2812 can maintain a reasonable +0 -3dB characteristic across a 30 degree horizontal window for all mid/high frequencies. Looking at this plot – / 3D3A/ Directivity/ Quad_ESL57/ 6.QuadESL57ContHor.jpg – we can see that, through the critical range of 2kHz to 5kHz, the ESL57 really only has a 10 degree horizontal window! To think of adding a wider dispersion driver to complement an ESL is folly. The biggest attribute of panel loudspeakers is their coherence across a wide bandwidth, there being no disruption (for the ear) caused by relatively abrupt changes in characteristics of drivers through the crossover region as commonly found in conventional multi-driver moving coil speakers. Nearly every example of panel loudspeakers which crossover to conventional drivers, whether in the treble, midrange or upper bass, detracts from this coherence. It is part of what makes an ESL such a special listening experience. True ribbon tweeters also suffer from reduced horizontal dispersion, particularly when horn loaded. There is no conventional crossover, per se, in a Quad ESL. Instead there is a very gradual roll-off (blending) of the panels either side of 1kHz which seems quite innocuous when listening.

Peter Comeau

Head of Acoustics




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