Some months ago David from Victoria purchased a full DIY ESL IV kit, and a pair of Hypex NC250MP Class D amplifiers to drive them. These are his comments on the ease (or otherwise) with which the kit goes together, problems encountered and overcome and the sound quality of the end result.

Before going into David’s comments I must mention a problem he encountered on the way. After building the speakers and installing them into their frames he powered up, one speaker performed as expected the other was at half loudness. After seeking advice for the checks required to determine where the problem lie he discovered a loose connection in one of the transformers, indeed one of the primary wires pulled out of the transformer. After a simple repair, everything worked as it should.

The cause of the loose wire is not known, it may have been a bad joint made at the factory or possibly the cable was tugged during packing etc causing the joint to break. I suspect it was initially a poor solder joint because the wire was not broken, it was simply loose.

Under normal circumstances we would simply replace the transformer but David was keen to get the speakers running as what he heard showed a lot of promise. He decided to try to fix the loose wire and succeeded.

Morning Rob,

Great news, the wire has been repaired and the ESL IVs sound fantastic.

Photos of the repair are attached.

The repair has fixed the low volume and the low pass filtering effect so the overall sound is a lot more balanced both L-R volume/positioning and frequency range with the top end cleaner, sharper and less reserved.

I can now think about fitting the Hypex amps and tinkering with the locations of the ESLs to optimise the sound and imagery.

Can I say that I have thoroughly enjoyed this project. I will admit there was a little bit of “ leap of faith”  to convince me to commit at the start but talking to you beforehand convinced me to give it a try. All the way through the project I have been greatly appreciative of your support both when there was an issue and sharing my joy when things just went to plan. The results are outstanding and I could not be more satisfied, indeed ecstatic. Your selfless, unwavering support, communicating in plain, simple English guiding those of us who may not be electro-technical wizards has been amazing. You are a true gentleman and a credit to the audiophile world. It has been my pleasure and privilege to have dealt with you, if I am ever in Perth I will be looking you up!

Thanks and regards, David


I rarely ask clients to provide any form of review, the ones on our website are all unsolicited, however, in this case I’ve asked David if he would mind providing a breakdown of the difficulties he encountered during the build for 2 reasons. The first is for me to improve the method of construction and the detail in the construction manual, the second reason was to reassure any prospective customer that the full DIY kit can be built without any experience of this type of loudspeaker.

Clearly it is important that the builder possesses good handyman skills, has an ability to solder wires etc and has sufficient space for the construction.

There are no specialist tools required other than those found in a regular home with a mildly active handyman, electric drill, work top, screwdrivers, wire cutters, soldering iron etc. If you are reading this page you are probably one of those people!

David has agreed to provide some comments regarding the DIY kit - watch this space.

The rest of the story is his, warts and all!!

My experience constructing ER Audio ESL IV loudspeakers


My story starts back in the early ‘80s shortly after arriving in Australia with my wife, after emigrating from the UK. I was just getting the “HiFi fever” before I left and wanted to continue with it when in Melbourne. New hifi gear was way down the list for a couple starting a new life in a new country, but as I had passed on my KEFs to my sister I had to purchase something if I wanted to listen to music. My thought was to buy something worthwhile that would last. Cutting a long story short I bought a pair of Mission 770s. A “once in a lifetime” purchase I told the wife. I have had various amps and cd players but nothing that was “esoteric”. The Missions served me well and stood the test of time for decades. A few years ago and after a few hifi shows, and listening to a friends Martin Logans, I decided it was time to upgrade, the previous life-time was up. The pressures of modern life had been tamed and managed and so it was time for an upgrade of my own.

BUT - I was still very hesitant about the proposed cost of electrostatics, and thought what are the alternatives, if any? Enter ER Audio. I had been interested and dabbled in kit electronics over the years and seeing that there was a kit version for electrostatics available in Perth seemed to be the enticing alternative.

However, electrostatic loudspeakers are things of legend and mystique, surely you need to be a member of the magicians guild to learn the secrets, how could a kit electrostatic loudspeaker ever be paralleled with such distinguished names like Quad? – and for a fraction of the price?

Reading through ER’s website and noting that there were many folk both here and abroad that had sampled the Acorns, and more recently the ESL IV, and that their reviews were positively glowing gave me the urge to call up and chat with Rob.

Any doubts I had about having the capabilities to construct the ESL IVs were quickly allayed by Rob when he explained what was required and the skills needed. If you have a soldering iron, a multimeter, basic tools (eg drill and drill bits, screwdrivers, pliers, cutters, tweezers etc.) some basic electro-mechanical construction aptitude, and a bit of a give-it-a go attitude, then there would be no problem. As I have grown older, I am not sure about being wiser, but have certainly become more cynical. But when speaking with Rob I was immediately put at ease by his demeanour, understanding and gentlemanly character. I was now sold, keen and eager. Rob sent me a copy of the construction manual for the ESL IVs.

Note: I had been in contact with Rob some years before when dreaming of a potential pair of electrostatics and had a copy of the Acorn manual, so had an idea of what to expect. I didn’t think I could convince the wife to appreciate a pair of speakers each roughly the size of a door, but Rob mentioned he was working on an upgrade to the smaller ESL III - the ESL IV, and would be available soon. The seed was sown.

During the time of my order processing and delivery, Rob sent me an updated revision of the ESL IV manual. Comparing one with the other, and to a lesser extent the Acorn manual, I noted that there was the occasional cross reference detailing the Acorn specifics. This confused me a little, but a quick chat with Rob cleared things up. He said from day one, if you have any concerns, doubts, or worries, stop, call and discuss the issue. This I did on several occasions during my construction, and can honestly say this was most reassuring, with Rob explaining what was important and what was not so.

As for the actual construction, it went pretty much as per the manual. Admittedly I had plenty of time to take my time and did just that. It was my first major project after taking early retirement and so dedicated the hours to the construction. This does not mean that you must retire to make your ESLs, but I would advocate taking your time to get it right. They might be seriously discounted compared to manufactured off-the-shelf products, but it is still a financial and time investment. Worth every cent, I might add.

Tip 1. Read the manual prior to starting– a couple of times would be recommended. The manual actually says this. It helps to get a bit of understanding of what goes into the ESL, how it all works, what should happen and what to do if it doesn’t. Don’t be overly concerned if some of it seems to be too much, as long as you get some of the basics. Just remember don’t panic, stop, and call Rob!

Tip 2. I would suggest not throw out any of the packaging. I found it all very useful when having to stop for the day and put everything away (out of harm’s way), knowing the panels and parts were secure and safe, and separated within a sturdy box. I even used the MDF sheet as a base board to protect the kitchen benchtop when soldering etc.

Starting with the gluing of the stators, everything you need is included in the kit. Be careful to glue the spacers to the correct stator. At one time I had the wrong one in my hand. I also had a slight issue with the spacer pillars in that they were supposed to snap into position. Mine seemed to take too much force to get them to sit properly. So, a call to Rob, and a little adjustment with a drill fixed this issue.

Tip 3. When gluing the spacers to the stators be careful not to get any adhesive on your fingers. I found I got a little bit on my finger when placing the cap back on the bottle. I thought I was being clever by having a damp cloth at the ready to wipe my finger. It wasn’t until later in the build that I noticed white finger marks etched into the black of the stator panels. Rob explained this was adhesive residue transferred from my fingers to the stator panels, which could be removed with a gentle rub with some acetone.

The next phase was to solder the surface mount resistors to the stators. These components are small, I needed extra glasses for my old-eyes, and a steady hand to place the blob of solder paste on the pads and then place the resistors. This took a bit of concentrated effort, to ensure enough solder paste, but not too much, and then place and hold the resistors in place while soldering using a pointed iron. Like most things, once you have done a few the rest get a bit easier.

The next tricky bit was the tensioning of the diaphragm film. I say tricky but if you follow Robs instructions, you will be surprised as to how well it all goes. The important thing in my view is to have a suitable worksurface. I used a sheet a glass. I thought that glass would be easy to clean, would show any dirt or particles, and not produce/shed any particles. I went to the local recycle depot for my sheet. They didn’t have glass but did have mirrors. The one I chose, based on size required was an older mirror. This turned out to be good in that older mirrors have a thicker glass panel than newer mirrors. The downside I discovered was that when I cleaned up the mirror some of the silvering backing came away. This meant I had to remove all the backing and thoroughly clean both sides of the glass panel. Fortunately for me I was in no hurry, but you might want to consider this if you go down the same path.

Tensioning the film was straight forward once you did the first few strips of tape. Again, the tool you need for this, a simple spring balance, is included. My kit was missing the roll of “Bear” cloth tape that is used for holding down the film. I questioned Rob and asked if the PVC tape that was included could be used. – NO. PVC tape will stretch; it must be cloth tape. A quick trip to the local hardware warehouse (in between lockdowns) and a few dollars later I had the right tape. Rob insisted that he could send me the correct tape, but rather than wait how ever long Aus. Post would take, it was easier to pick up the readily available tape from the hardware warehouse. Initially you might have doubts, as I did, as to the method to produce an even tension, but as you follow Robs instructions the ripples in the film gradually disappear revealing a smooth, tensioned film ready for the next step.

Tip 4. I found the Mylar a little difficult to handle from the roll. If you use kitchen wrap you will know what I mean, only the mylar is a fraction of the thickness of the kitchen wrap making it very flimsy and subject to any breeze or waft of air. I found that loosely taping the edge of the film to the glass, I used masking tape, then running a length of masking tape over the top of the mylar extending and inch or so beyond the edge where it needs to be cut to length made it much easier to handle and to cut. I simply used a sharp knife to gently cut through the centre of the tape and through the mylar film. This also left the edge of the mylar on the roll with a “weighted’ and protected edge, easier to handle for the next panel.

Once the mylar was glued to the panel and removed from the glass worksurface the next step was to apply the conductive coating. Another chat with Rob was required here to verify the correct quantity of fluid and the best method to apply. Sometimes a quick chat person to person can replace thousands of well-meaning written words. Ever obliging Rob is more than happy to keep you on the right track.

The rest of the panel construction was straight forward, simply following Rob’s instructions.

The same applied to the putting together of the EHT supply and connection board. Pretty basic soldering skills is all that is required, just remember to place any directional specific components the correct way around (diodes, electrolytic capacitors etc.). The photos in the manual help here.

By now, you are getting excited as you are getting closer to the last of the construction and putting it all together. BUT WAIT, you need a frame to sit the panels in. For me this was the frustrating part. We were in and out of lockdowns, materials were in short supply, deliveries would seem to take for ever, and not all the goods were delivered. You couldn’t visit the warehouse to select your materials you had to hope.

Tip 5. Some of the materials might not be available locally. I had to order foam tape and speaker cloth on-line. Do your research early, chose what you need on-line (especially anything that needs to come from China – which is just about everything) and get it ordered early.

I spent quite a bit of time “designing” my frames, working out how to create the right profile for the panels, and as I mentioned, researching what was available during covid restricted times.

I think this was more challenging than the actual electrostatic panels and supplies construction. Rob does provide some suggestions in the manual, but you need to work out the details. I created a timber frame with various off-the-shelf sections glued and screwed together to create the profile I wanted. Mounted inside the frame at the bottom was a simple box construction to house the power supplies and transformers.

Once my frames were ready, (including the grille cloth), the panels were mounted, and the electronics installed and connected. Again, just following Rob’s instructions everything seemed to go by the book.

Powered up and putting on some music and hearing them for the first time gave me an extremely satisfying feeling. Not only was I listening to another level of music reproduction, but I MADE THEM. It was extremely gratifying to know that I had built a piece of hifi excellence, a nice piece of furniture, something that was going to give me endless hours of enjoyment.

Once I was over the initial euphoria of the first listening tests, I noticed that I had to alter the balance across the stereo stage to get central sounds/voices etc in the centre. Listening more closely I also noted that one channel was less top-end crisp. I suspected it might have been my second hand Amber power amp beginning it’s end of life cycle demise. But a couple of quick tests identified it was actually the ESL.

Ohh nooo!!! Shock horror – I stuffed up and one of panels was not working correctly? I would have to change panels around to identify which one(s)? Hold on – Stop – Call Rob!

After a chat with Rob, I had a list of things to check and try. We quickly identified that it was not a panel (thank goodness) but one of the transformers. This was a surprise, as what could go wrong with a transformer? It turned out to be a poorly soldered wire connection under the insulation. Rob was more than happy to send a replacement transformer, but I asked if he wouldn’t mind me trying to fix it. Some more guidelines from Rob and some careful cutting and soldering and voila! – a successful repair. Rob explained how the mal-functioning transformer would affect the volume and frequency response of the panels. I was back on a high. Firstly, I had made the ESLs, then I fixed a fault. Having the knowledge that Rob was only a phone call away gave me increased confidence during the build and the subsequent “repair”.

I suggest to anyone considering going down the DIY path, the fact that you are considering it should be enough to convince yourself that you can do it. Ok you might need to buy some basic tools if you don’t already have them (eg a basic multimeter) you might be able to borrow perhaps if you know someone who might have? But I would strongly urge you to give it a go.

I found Rob to be ultra-willing and helpful and will give you as much time as is needed to resolve any issues, and to pass on extra tips. I am now going through the finessing of placement relative to room and seating position etc. Once that is finalised, I will be dismantling to allow fitting of carpet spikes under the boxes. I want to wait until am completely happy with the placement before fitting the spikes as due to their size they are slightly more awkward to move than my previous Missions. I don’t want to risk the so far acceptance from the wife, with potential torn carpet trying to move while on spikes. The journey continues………tube pre-amp next? Shhhh…. don’t tell the wife just yet, at least not until she chooses a new AV cabinet/entertainment unit.



David’s ESL IV journey and some tips for DIY’ers.

Daves ESL IV

For some construction tips read on after the photograph.

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