Jason's DIY Audio

DIY Back Loaded Horn Speakers / BLH - Fostex FE206E in a Dallas III Cabinet Update 03 - Coral 8A-40

2008-04-02T22:57:00.008+08:00

First off a very big thank you to Yeo of diyparadise for lending me a pair of his Coral 8A-40s to audition in my Dallas III cabinets. I was initially surprosed at how small the light the Coral 8A-40 drivers were compared to the Fostex FE206E. I understand that full range driveres depend on massive acceleration of the cone to deliver the entire range of frequency, so I wondered how Coral 8A-40's smaller magnet would compare to the Fostex206E's massive magnet that is at least 3 times larger and heavier?...I met Yeo one fine sunny weekend in January 2008, at his house. I took the opportunity to listen to his setup, the Coral Beta 6s in Hedlund cabinets. In terms of height the hedlunds are indeed an imposing pair of speaker, enough to give the "Tim the Toolman Taylor" in any of us the argh argh argh. But in real terms, both the Hedlunds and the Dallas III cabinets are similar in size, Hedlunds being a single fold horn and the Dallas III is a double fold horn. Once Yeo got his system up an running, we played some Led Zeppelin and cranked up the volume. Wow those speakers ROCK. They played loud and fast. That said, the first thing that hit me as odd was that the high frequencies were missing. Thus a lot of the "ambiance" in the music was lost. I would have loved to stay the entire afternoon and flip through different genre of music to see how the speakers would fare but I was in a rush. I listened to the speakers for less than 15 minutes in total. I know this is too short a time to form any real opinion. Here are the Fostex FE206E and the Coral 8A-40 front view. The Coral drivers a bit dirty as they are vintage stock....Now to my Fostex FE206E in Dallas III cabinets, I had the speakers installed in the cabinets for over 4 months now and I have been listening to them almost daily. I play music through them every evening even if I don't intend to sit down for a listen, just to give everything a daily workout. The wire leads were still sticking out of the cabinets in an unsightly manner. Not only is this unsightly, Ron, the Dallas III designer has said to me that this would cause a loss in the horn efficiency which translates to its ability to play low and loud. Why? you ask... Well its because the wires will prevent an air tight seal between the drivers and the cabinets. But still I procrastinated, I left the speakers unfinished because it sounded so good to me.

After some urging from my other half, I decided it was high time I finished off the speaker and tested the Coral 8A-40s that Yeo was gracious enough to loan to me. So I installed a pair of binding posts to clean up the wire mess. And I installed rubber gaskets so that I could create an air tight seal for the drivers and the cabinet.

The first order of business was to test the Coral 8A-40s. Being new old stock, I was conscious of the fact that the drivers would not sound their best initially. And as I had already surmised they did not sound good at all initially. I left them playing off and on for about 2 weeks. I estimate that the drivers must have played about 50-60hours. I could tell that they were improving. Even my other half commented that the speakers sounded good. With this affirmation I thought it was time for me to sit down for a listen.

The Coral 8A-40s sounded very similar to the Coral Beta 6s. Guess there is a family resemblance. These drivers can rock, put in some classic rock and you are good to go. Put on some slower Jazz numbers and I discovered that the vocals were good too. Music was "fast" and "tight". However, the drivers exhibited the same high frequency roll off, just like its more sort after brethren, the Coral Beta 6. And like I said earlier, the music was missing some ambiance. I could not get used to this especially when I had an pair of ESLs that excelled in this department. I know that there are many who will not agree with my evaluation of the Coral 8A-40's high frequency roll off. But these are what my ears are telling me. To all Coral owners, you have a gem of a driver, and for the price there is no speaker thant can compare.

So out came the Coral 8A-40s and back in went the Fostex FE206Es. If you have been observant, you would have realised that by this time I have been listening to the Corals 8A-40s in my bedroom exclusively for 2 weeks. Other than the High Frequency roll off, I had no other complaints about the Corals. At this point I could not compapare the Coral 8A-40s to my own Fostex FE206Es as I had trouble recalling what the Fostex FE206Es sounded like.

As soon as I had the Fostex FE206Es installed, and had music playing through them, I realised that they were a whole order more musical and also clearer compared to the Coral 8A-40s. It was like a veil was lifted. Just the clarity of the music was astounding. To make sure this was not a figment of my imagination, I swapped between the Corals 8A-40s and Fostex FE206Es a couple of times and even asked my other half to have a listen. And both of us preferred the Fostex FE206Es. However I noticed that the Coral 8A-40s had a slightly fuller mid bass, which made male voices and rock music sound forward. Both drivers played quite low, Corals 8A-40s till about 49hz and the Fostex FE206E till about 43Hz before dropping off. Here is another view of the Fostex and Coral Full Range Drivers. Not all 8" FR drivers are made equal... the massive magnets does make a difference....

And u know what, I slapped on some Def Leppard, Queen, ACDC.... the Fostex FE206E in the Dallas III cabinets ROCKED too... as hard as the Beta 6s in Hedlund cabinets.

Feel free to leave your commets. Or Return to Home.

DIY Electrostatic Loudspeakers / ESLs - Problem with Treble Frequency Solved

2008-01-24T12:15:00.000+08:00

The ESLs have been performing very well up till about 3 months ago. One of the speakers developed a problem. The volume on one of the pairs was softer than the other, not by much but enough to shift the stereo image over to one side. After more listening I deternimed that it was the treble frequencies that sounded softer compared to the rest of the frequency. With advise from the designer I proceeded to trouble shoot the faulty speaker:

Thoroughly clean the diaphragms and stators using a vacuum cleaner.
Visually checked all surfaces to ensure that was no dust or insect causing a leak between the diaphrams and stators.
Rechecked and tightened all connections.

Still the problem persisted. I then proceeded to ensure that none of the other equipment that was connected to the speakers caused the problem. To do this I did the following:

Swapped the speaker cables
Used another amplifier
Used another CD player

Again, no change, the problem persisted. With all the possible culprits eliminated, the finger pointed at the electronics, and since the problem affected the treble frequencies, it must be one of the 1.2ohm resistors connected in series with the speakers. Rob had replacement resistors sent to me, free. I promptly replaced the offending resistors and the problem is gone. The ESLIII are now 100% again.

Thanks goes out to Rob of ER Audio for the great support.

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DIY Subwoofer - Rythmik Audio DS12 kit - Listening Impressions

2008-01-22T11:06:00.000+08:00

After living with the Rythmik Audio Subwoofers for a few months. I have come to the following conclusion:

This DIY subwoofer has exceeded my expectations. They are perfect for my Home Theatre setup... rattles the furniture and ceiling boards when the need arises. I have the subwoofers crossed at about 80Hz using the AV receiver.

However I am still working on integrating them into my Hifi setup. For my Hifi setup I rely on the plate amplifier's cross over adjustments. I have the crossover set at about 100hz. I am still experimenting with the subwoofer placement, but right now, it is sitting in front of the room right in between the ESLs. For Hifi purposes, there is no doubt that the subwoofer produces non bloated, accurate and articulated bass notes. On most pieces of music, integration with my ESLs are seamless where I don't even know if they are turned on or not. However on certain pieces of music, commercial pop mainly, the producers mix an awful lot of bass and when played thru the ESLs and the subwoofer, the bass sounds over emphasised and exagerated.

Here are more of my observations:
1. Clarity of the bass is top notch. No boom or just a deep rumble... you can actually tell the instrument and the note that is being played. This alone quality alone sells the subwoofer!!
2. The subwoofer adds a lot of "atmosphere" to the music. The music seems "fuller bodied".
3. The subwoofer produces bass that is "tight and fast" enought to keep up with my ESLs.
4. The ESLs and subwoofer setup sounds best on accoustic pieces, classical (pipe organ music is fantastic) and some slow rock pieces.
5. Bass extension is great despite the size of the driver and the cabinets... roughly 2.1cuft. Saves space while not sacrificing extension or SPL.

I don't have any real testing equipment except for the ratshack analog sound analyser. And from some of the frequency sweeps I have done, the frequency response is flat down to 13hz 3-5db when damping set to High and extension set to 14hz.

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DIY Subwoofer - Rythmik Audio DS12 kit

2008-01-18T10:50:00.000+08:00

Here is another of my speaker projects from 2007. What is it you ask, well its a subwoofer.My primary objective was to use a subwoofer to bolster the lowest frequencies of my DIY ESLs. But this was a unique situation as I did not want to have a situation where the bass sounded disembodied from the rest of the music like the Martin Logan ESLs!! So not just any subwoofer would suffice. I have listened to many subwoofers in my day. What I considered great in my youth (head-banging days), I now consider bloated and woolly, lacking definition and musicality. All the commercially available subwoofers just play catch up with the rest of the music. My ESLs called for a subwoofer that is both musical and accurate (some might even call it "fast") So my search for such a subwoofer thus began.

These subwoofers also had a second duty, which was to serve as the subwoofer to my Home Theatre setup. This double duty required a truly spectacular subwoofer, and at one point I considered DIYing 2 subwoofers. After much reading I came across a category of subwoofers using SERVO technology. Now subwoofers utilising servo technology is nothing new, several commercial maufacturers use it in their offerings. Servo subwoofers utilise feedback sensors to ensure that the driver is performing as it should. In addition to this servo tehcnology, I also opted for a sealed subwoofer as this sounded most accurate and musical to me. Enter a direct to consumer manufacturer called Rythmik Audio. Rythmik Audio offered DIY Subwoofer kits based on TC Sound's drivers and specially modified plate amp.

The kit of my choice is the DS12 Standard kit for a sealed subwoofer design. The driver and plate amp were modified to utilise Direct Servo technology. In addition, the plate amp had adjustable circuits for bass extension and SPL. Wow this was the 2 subs in one that was needed to pull double duty in my setups.

Here is an extract from Secrets of Home Theatre and High Fidelity article about the kit:

"There are many advantages to using a servo-controlled system for a subwoofer. As previously described in the review of the Titan sub, the servo design allows you to use a smaller cabinet to achieve the low-end response. The feedback controller also protects the driver from being overdriven, which would cause damage to the voice coil.

The feedback loop in the Rythmik sub is a combination of current sensing and velocity sensing feedback. Unlike most servo designs on the market, Rythmik takes on a minimalist's approach. There are no active devices in the feedback paths. The feedback path is purely comprised of resistor and capacitor networks. In contrast, in accelerometer based designs, op amps are used to amplify the motion signal, therefore, becoming a possible source of audible degradation.

The way Rythmik designed the extension filter was such that, without the extension filter, the frequency response (from the sub, not from the amp) will be flat to below 10 Hz. However, this type of design would not be practical. So Rythmik inserted an additional single 2nd order high pass filter with adjustable fs and Q values by changing the resistor and capacitor values of the filter. That sets up the ultimate extension of the frequency response, which allows the user to select between maximum extension and maximum playback SPL."

Having never heard these subwoofers and armed only with glowing reviews from owners, diyers and magazines, I proceeded to contact the designer, Brian Ding. A pleasant fellow, ever willing to answer your questions and help you in anyway possible. After several correspondenses with Brian Ding via email, I felt convinced that this was the kit for me. Musical, accurate, articulate, goes down flat to 10Hz, adjustable extension and SPL what more would I need. So I made the plunge and promptly ordered the DS12 standard kit. Shipping to Malaysia was not cheap. But after a couple of weeks, the kit arrived.... comprising of 1 12" driver unit and a 350 watt plate amp with humongous toroidal transformers and a bank of 4 caps!! Here are some pictures...

The DS12TC 12"TC Sounds based driver, and notice the large 2" magnet. This baby is heavy. Its not the most impressive driver from TC Sounds' stable, but it does its job well.
Top View. This version comes with a Black Anodized Aluminium Cone.Side View, showing the Sensor Coil. The sensor coil sends feedback plate amplifier's servo circuit about the cones movement and position. TC Sounds specially manufactures this sensor coil based on Rythmik Audio's design.Side View, showing Driver Coil.Bottom View.Here is the 350 watt A370 plate amp.So what's missing? The Cabinets of course. Cabinets were a simple affair, a cube with cross braced internals, thick walls.... and an open/glass top so that I can see what's inside. I made them using facilities in my Uncle's woodworking shop. I had them made out of MDF as that was all we had lying around. Here are the pictures of the cabinets. The internal cross braces.Front quarter view.Many people ask if I make the cabinets by myself. I do make it myself but I get a lot of help from my Uncle who is a carpenter by trade. He has a woodworking shop where I make use of the many equipment a home builder would otherwise have no access to. Here is a picture of part of the workshop. The installation of the plate amp and driver units were a simple affair, everything is sealed using silicone adhesives and screws. I use silicone as I had to ensure that it was air tight. The top glass cover is 1cm thick temperred glass. It is attached with nothing other than silicone. Here is a picture of the installed plate amp, notice the large toroid and bank of 4 caps!!Front view showing the 12" driver unit.Another view from the top showing the internals. Incidently, the internal walls of the cabinets have now been lined with 1cm thick foam to reduce internal reflections.Another view from the top showing the driver's backside. The rear view of the cone moving during high excursions is a sight to behold!!Feel free to leave your comments. Read my Listening Impressions or return to Home.

DIY Back Loaded Horn Speakers / BLH - Fostex FE206E in a Dallas III Cabinet Update 02

2008-01-17T16:41:00.001+08:00

I asked Ronc if the radiused corners of the Dallas III would have a detrimental effect on the sound compared to the angular Dallas II designs. Ronc had this to say:

"Nope! just a gain in efficency because there is less turbulance in the wavefront as it traveles. Down side is a slight increase in mids coming thru the mouth. However the actual horn action begins a slow roll off at 247 hz and ends at around 400 hz. From there the baffle action takes over (overlaps with the horn roll off) and as the frequency increases finally hands off to the driver. The absolute lowest frequencies are a TL action which blend into the lowest horn action at around 120 hz. The higher frequency TL ripples are then blended with the horn action. This results in a smoother mid bass."

So I am really glad that the desicion I made, which were originally based on aesthetics, did not result in an inferior sounding speaker. Especially considering all the effort that has gone into the build.

Feel free to leave you commets. Read on to my next update 03 or return to Home.

DIY Back Loaded Horn Speakers / BLH - Fostex FE206E in a Dallas III Cabinet Update 01

2008-01-15T10:43:00.001+08:00

I submitted my speakers for a public critique on various DIY forums. I have also had the luck of making contact with Ronc, the designer of the original Dallas, Dallas II and Dallas III. He has confirmed that he designed the Dallas III. So I credit these speakers to Ronc.

I have received the following advise:

1. The side walls and internal structure could do with more Support or Bracing. This is something I probably could not do without massive cutting up of the cabinets as they are already sealed up.

2. Seal up the drivers to the driver flange using silicone as leaks would affect Low Frequency performance. I will do this as soon as I have installed the binding posts and also after I have tested the Coral Flat 8 / 8A-40... courtesy of Yeo from diyparadise. I know that these cabinets have been designed for the 206, We just want to experiment with the Corals that seem very versatile.

3. Add 1-4ohm resistance in series with the speakers. It will bring up the LF response by raising the Qes which in turn raises the Qts. With the efficency of the 206/Dallas, this loss of efficiency should not be notice.

That's it for the time being. I am adding pictures of the internal side profile for comparison. Presenting the Dallas II...
and the Dallas III... much more attractive, but does the radiused corners affect the parameters and so the sound.... negatively?Feel Free to leave your commets. Read on to my update 02 or return to Home.
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DIY Back Loaded Horn Speakers / BLH - Fostex FE206E in a Dallas III Cabinet

2008-01-14T15:35:00.001+08:00

Horny, I'm home. Funny? I have been waiting a longtime to say that... And I have also been waiting equally long to complete these BLH speakers. So why did I choose to build a horn speaker since I have already completed the ESLs... basically I wanted to experiment with the various speaker technology and designs. I have never been satisfied with the multi coned, multi way speakers. They have never sounded right to me, save for a few very well integrated 2 way speakers. That is why I am attracted to full range drivers and ESLs. The ESLs produce music from a single surface which makes the music "cohesive" for lack of a better word. The music is accurate, fast, with pin sharp imaging and well... they are musical. Instruments sound as they should, piano sounds like a piano, guitar is a guitar... it just jives. I love my ESLs to bits.

The "not so good" of the ESLs are that they are a pain to drive, needing serious wattage and current from a amp that puts out heat like an oven... I kid you not. A monster amp with 200watts with ample current and able to deal with the quirky impedance of the ESLs are what they need to perform their best.

Now on the other end of the scale are these eccentric full range drivers. My first memorable experience with them were in an Audio Note showroom. I forget what amp was on show, but I am quite sure it is one of the famed amps from Kondo's stable. There were also some funny looking speakers singing in the back room. I asked the sales attendant and found out that they were.... Lowthers was the name. They resided in some cabinets huge cabinets that I mistook for a chest of drawers!! They sounded lucious and "complete"!! What do you do when you don't have a couple of hundred thousand to plonk onto one of Kondo's famed amps with a matching lowther driver and those very fine cabinets... DIY of course...

Fast forward 10 years or so, I finally decided that it was high time I got my tube amp plus a pair of horns setup to recapture the magic. So I shopped around for an amp and speakers. I thought I was going to DIY a tube amp, but I came across a deal for a Made in China tube amp that I could not let go. So I bought myself a Little Dot III tube amp with switchable modes between Triode and Pentode. This amp sounds beautiful and only produces 2 - 3 watts, but what beatiful watts they are. All parts of the amps including the tubes are made in china save for the volume control which is from alps and power connectors from amphenol. I may yet DIY a tube amp in the future.... you never know. Now for the star of the show, the speakers.

After scouring the internet I considered, various forms of full range drivers... in bass reflex, open baffle, and various flavours of horns (spiral was really interesting). I settled on one of the best bang for the buck Fostex FE206E full range drivers that work best in a back loaded horn configuration. People tell me that Corals are better, they probably are better but I could not find much information about them. The pair of Fostex 206E drivers cost me less than RM600 shipped from Japan. The only drawback with these full range drivers that I garnered from all that reading was the inherent "shout" that had to be dealt with or tolerated..... As for the BLH design, I can't design any speaker to save my live. So I scoured many sources and forums for something that I could build. I came across several designs and of course there is the recommended design for the 206E from Fostex. I then happened across http://www.fullrangedriver.com/ . This site contained much information about horns and full range drivers, horn calculators, designs and a collection of people passionate about them. After much reading I was taken up by a BLH design made specifically for the Fostex FE206E called the Dallas II. The completed cabinets looked like the usual box type folded BLH. The designer goes by the name of Ron in the fullrangedriver forum. While I have never listened to these speakers, something about this guy just struck a cord in me. In addition several DIYers had built the Dallas II and were very happy with the result. I must admit that the rectagular/boxy Dallas II did not appeal to me aesthetically.

Then from out of nowhere the Dallas III surfaced. Now I am not sure if the Dallas III was actually designed by Ron himself or drawn by a fellow enthusiast. But the Dallas III was a much more aesthetically pleasing speaker. The externally the Dallas III had discarded the boxy look for a curved and flowing design. The internal folds are smooth as well, containing no sharp angles. For all intents and purposes the dimensions of the Dallas II and III were identical. So I thought I'd try to build this. The fact that it looked nice, gave me an oppurtunity to blend my music into my surroundings. After showing the desings to the Home Minister, we desided it would be nice to have them in our bedroom, as a sort of functional Art Deco piece.

These sepakers sound as beautiful as they look, they are really enjoyable and can go really LOUD. Who new what 2 watts could do? As luck would have it I have a large bedroom which suited these speakers fine both visually and sonically. Bass while not prodigious is fast and accurate. It goes down low to about 35Hz. The inherent shout is only evident when you are listening on axis, with the speakers suitably toed in/out, its hardly noticeable. It plays all music with equal aplomb. Bach's Dorian sounded great, Dire Straits' Money for Nothing was really rocking, Janet Seidel's Agua De Beber was pure liquid.... I am listening to CCR as I am writing this post, very nice!!

Presenting the Dallas III and Fostex FE206E.
Front view of the speakers, I placed a 6 inch ruler so you can get appreciate the scale of these behemoths, while not as big as my ESL, they are still more than a handfull. They stand about 1.2m tall 45cm deep and 30cm wide. The backside.... pretty uneventful here... A view of the business end of the horn. The wires are hanging out coz I have not installed the binding posts yet. Standing next to the Dallas III are my old faithful... TDL's RTL2 transmission line speakers. They just sound dull and wooly compared to the Dallas IIIs. The Dallas III twins, sitting pretty in my room, with the tube amp that in then middle. Internally, the Dallas III back loaded horn is a folded horn... 3 folds to be precise. Here is a picture that shows the folding. How did I make the bends? Trade secret! And here is a side profile showing the beautiful curves...Also presenting the Little Dot III, this little 2 watter is a beauty, just ignore the cheesy blue leds. Comes with an external power supply. (The Little Dot III amp that drives the Dallas III... coincidence... I think not!!)And finally a closer look at the Fostex 206E, the cone is made from banana pulp. The music is achieved thru massive acceleration of the cone using this massive magnet. The magnet measures almost as large as the speaker basket.... More of the driver unit... Feel free to leave your comments. Read on to my update 01 or return to Home.
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DIY Electrostatic Loudspeakers / ESLs - The Cabinets and Final Installtion

2008-01-14T14:42:00.000+08:00

Fast forward a couple of months, the panels have been in my listening room, leaning against the wall, playing faithfully. I have been listening to them almost daily without fail. They never fail to amaze me. I finally decide that the panels should be placed in their cabinets. Fortunately my Uncle is a carpenter by trade and he has all the tools and raw material that I need to make the cabinets. It took me about a week to design the cabinets, borrowing heavily from examples found in the user manual and the designer's website. After much discussion with my Uncle, we had all the details of the design ironed out and after a couple of overnighters at the workshop, I (as in my Uncle) complete the cabinets. I used a hardwood, my Uncle told me the name but I forget. More than a few nails and screws have been broken off as we were constructing the cabinets. Joints were mainly glued and then nailed. The cabinets featured a removable cover which you will see below. This removable panel is secured by screws. The cabinet is constructed out of 2 main modules. In this picture you will see a box with 4 aluminium legs. This box measures h320xw600xd250mm. This will serve as a base for the ESL panels. It will also house the EHT and transformers. Behind the base and leaning against the wall, you will see the removable panel. This panel forms the rear of the base. The large round hole will house the speaker binding posts and the small rectangle will hold the power cables connections.In the next picture you will see a large rectangular frame that will house ESL panels. The frame measures h1300xw600xd160mm. I did a mockup, and I was surprised as it seemed a lot larger than I expected. Its going to dwarf everything else in my listening room. It stands at about 1.6m. The frame holding the panels will screw onto the base as shown in the mockup. I originally wanted to make the base and the top using one piece of wood, but we did not have a piece large enough. Well, can't always get what you want...And here are the braces that will go into the top module. These braces serve 2 basic purposes. 1. To 'brace' the top module so that it is more rigid and resists sideways motion. 2. To serve as a backing to support the panels. The braces are also radiused so as to reduce reflection.Before I can install the panels, my first task was to install the channels where the panel will sit in. This was a simple affair, just nailing the appropriate length of square cross section wooden rod into the top module.Here is another picture of the channels being nailed into place.With the channels installed, I test fit the panels. Perfect fit! I love the look of the ESLs, really majestic. I am wondering if I need some kind of cover or should I leave them naked. Opinions...Rear view of the panels during the test fitting.A closer view of the Panels sitting snugly in their channels.I also test fit the braces. While the fit is good, but the support points are too narrow don't quite line up with the edges of the panels that it is supposed to support. I will have to fashion a new support that will extend to support the all the panels properly.Satisfied that everything fits, I remove the panel to clean them and the cabinets up. Here is a picture of the completed cabinets without the panels.Here is another view of the empty cabinets. Notice that the channels at the bottom are different from the other channels. They are screwed on to aid easy installation and removal of the panels. They were an afterthought and so the wood is not finished in the same colour as the rest of the cabinet. Notice that I have already predrilled holes in between the channel brackets so that the wires can be passed through to the base that will house the EHT supply and transformer. This will make things look neater.I clean the cabinets up thoroughly and give the room a good vacuum. I then start installing the panels into the cabinets. I make sure that all screws are tight. Here is a rear view of the final install.I place the EHT and the audio transformer into the base. I connect all the wiring. The ESLs are now in position. They are right next to the side wall and about 2 feet from the rear.After making the final connections, I turn on the ESLs, put in some Nat King Cole, Marsalis, Hall and Oates, Eagles..... I am left speechless. The ESLs were used without the cabinets for a good 2-3 months and they were just wonderful. But now in a proper enclosure.... they just got better. The sound emanating from the ESLs has just been elevated one level better. It sounded fuller, mid bass has much more presence and goes the panels go down another half an octave. I'll whip out the sound analyser for tests later. For now I just want to go enjoy the ESLs.Feel free to leave you comments. Read about my Treble Frequency Problem or return to Home.

DIY Electrostatic Loudspeakers / ESLs - Electronics and First Listen

2008-01-11T14:24:00.001+08:00

With the panels completed, I move on to assemble the electronics. At this point I am really eager to hook the panels up for a test. The electronics assembly is really simple. This mess of wires below shows that the diaphragm is connected to the EHT supply, the stators are connected to the audio transformer, the EHT supply is connected to the voltage regulator and finally the audio transformer is connected to the amplifier's speaker outputs. This is so simple I complete this in no time at all.I flip the switch... and no sparks. So I go ahead and adjust the bias voltage for the panels. I let the panel charge up for about an hour before I do anything further with them. Here is a picture of the voltage regulator used to adjust the bias. At this stage put some music on and turn up the volume. Well, I hear music coming out through the panels. If only you could hear them. All the superlatives that you have ever heard reviewers and owners sprout about ESLs apply here. These speakers were made for music. It’s an all new listening experience with all my CDs. Instruments sound so real... one thing that struck me was the snare drum from some acoustic pieces. None of my cone speakers, my Fostexs full ranger included can reproduce the sound of a snare drum as accurately as the ESLs. If you have taken notice of the sound of a snare drum you'd know what I mean. From rock to techno, to vocals, to classical... the music is just great. Even my better half who is quite critical of audio equipment (but not fussy) said that they were very "nice".

Bass is a bit lean, so when I play Bach's Dorian, it just isn't quite right. But then I have yet to hook up my Rythmik Audio Sealed Subwoofer, which should fill up the lowest octave demanded by organ music. I will be going through some frequency sweeps later, once the speakers have had some time to "loosen up". But from what I could tell, it plays from 50 Hz to 20 kHz very convincingly; it then starts dropping from 50 Hz to 30 Hz... to virtually nothing much below 30Hz. At this stage the panels are simply leaning against my wall as I have yet to complete the cabinets. Yet they sing beautifully. Can't imagine how much better they will get when in their proper enclosure and placed properly. Here are the 3 amigoes that make up the left side resting against the wall.Somemore thoughts about bass thru ESLs. I think the ability of the ESL to do bass is really dependent on a host of factors and the most important one is step up transformer. For reasons that I have yet to understand, the number of octaves that a transformer can handle has a practical limit. I read the limit to be 6-7 octaves. One solution is to use a high freq transformer for a treble panel and a low freq transformer for the bass panel. The problem here is working out the crossover and integrating the panels. However I have it on good faith that the ESL's that I have DIYed has a freq response of +or- 6db from 35Hz to 200Hz. However, I do believe the cabinet and placement plays a very important role in achieving this, particularly the use of walls for reinforcement.

The following is a quote from ER Audio about their proprietary 1:90 turn transformer:

"Response is < + or – 2dB, 20Hz to 20 kHz driving a 1.2 nf load. A 0.6 ohm resistor is used in series with the primary to quell a rising response which peaks at 25 kHz (resonance). This resistor may be varied to adjust the response for different panel loads."

At the moment I have yet to experiment with sound absorbers and diffusers. I will have to when I have the ESLs in the cabinets and properly placed.

The next step, The Cabinets and Final Installation

DIY Electrostatic Loudspeakers / ESLs - The Diaphragm Conductive Coating

2008-01-11T11:39:00.000+08:00

In this step of my build I, make the diaphragms conductive. This is a relatively simple task. But firstly I had to carefully clean the diaphragms with methylated spirit. I did not have any lying around so I used medical grade alcohol swabs. A quick and thorough wipe with the swab followed by a wipe with some dry tissue did the trick. The swabbed, cleaned and dried diaphragms are now ready for the application of the conductive coating. See how clear and reflective they are...All panels swabbed and dried.Here is a picture of the bottle of conductive coating and the utensils for the job, a small plastic cup, a foam applicator and a syringe to measure the amount of fluid to be used.Specific amounts are used to coat each panel. This helps ensures the correct coating density for each panel. No guesswork here.Using the foam applicator, I carefully apply the conductive coating onto the diaphragm. I apply until all the liquid measured for the diaphragm is completely used up. This takes a little practice to get right.Here is a view of the coated treble diaphragm once it has dried. At this stage I started getting the feeling that the coating was a bit thick, more on this later.Here is a view of one of the Full Range Panels. Although it has dried, it would take from a couple of days to a few weeks for the conductive coating to cure. Again looking at the panels, I had a sneaky feeling that the coating was too thick.Next, I put the front and rear halves of the one complete panel together. The front half of the panel is made up of the support structure, the stator and a tensioned conductive diaphragm. The rear half of the panel is made up of the support structure, the stator and a strip of copper foil that will pass high voltage polarising charge to the diaphragm. This foil will come into contact with the conductive side of the diaphragm when they are sandwiched together. I place the 2 completed halves, front and rear together. I do a final check to ensure everything is in order before I marry the halves together. Notice the foil and the diaphragm will come into contact when they are sandwiched together.Carefully, the 2 halves are placed together. I ensure that they are correctly oriented. Then I bring out the plastic channels that will be used to clamp the halves together. A channel is required for each side of the panel. So its 4 channels per panel.Here's a partially clamped panel.Remember that I had this niggling feeling that the conductive coating applied earlier was a little too thick and did not go on as consistently as I would have expected. A quick check revealed that it was indeed too thick. Rob from ER Audio, said that this will lead to a degradation of the Bass. As such I must reapply the conductive coating again. The conductive coating must be diluted with distilled water. It’s my own fault really for not reading the instructions more thoroughly. But before I can apply the correctly diluted coating, I will have to strip the old conductive coating off. I was worried that I may damage the diaphragm and then have to start from scratch. But as it turned out the process of stripping is really very easy. The conductive coating is a water based acrylic, as such I needed an acrylic solvent to strip it off. Acetone was the best choice. All the local hardware stores do not carry Acetone. But I got lucky and found a can at Ace Hardware. I wet some tissue generously with acetone and begin wiping the conductive coating off the diaphragm. The stripping is actually very easy... just be generous with the acetone and tissue. Here is a diaphragm that I have completely stripped. I also clean the diaphragm with the medical grade alcohol swab. Incidentally, after the acetone and isopropyl cleaning, the diaphragm did not look any worse for wear. See for youself...I then mix up a batch of conductive coating, diluted to the correct coating density. Here is a picture of the correctly coated diaphragm.When viewed directly from above, the diaphragm is clear, but when viewed at an angle it has a bluish haze. This is exactly the outcome that I was expecting from my conversations with the designer.The entire process of stripping and re-applying the coating probably took about 2 hours. I am getting really good at this. Well the panel build is finished. I am finally able to clamp all the halves together.Here is a picture of the 6 panels, all finished.And another closer look at the 3 panels that make up one side of the speaker.Next I Install the Electronics and Listen to the panels for the first time.
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DIY Electrostatic Loudspeakers / ESLs - The Diaphragm Node Points

2008-01-11T10:44:00.000+08:00

In this step of the ESL build, I attach Node Points to the Full Range panels. The node points eliminate unwanted resonances and the single bass note resonance peak. Nodes points are where the diaphragm is fixed to the stator using silicone adhesive. Silicone is injected into the void between the diaphragm and the stator. The silicone spreads to form a "button" that holds the diaphragm to the stator. Here I measure the node points and then attach markers where the nodes are to be injected. More measurements. After measuring the node points according to the designer's specification I mark them off. I then begin injecting the silicone at the indicated markers. The silicone adhesive is thick and spreads evenly between the diaphragm and stator in an oval pattern. Each node point is about 10mm in diameter.Here is a completed node point, freshly injected.More node points completed. View from of the node points from the diaphragm side of the panel.I leave the node points to cure overnight before commencing the next step which is to apply
The Diaphragm's Conductive Coating
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DIY Electrostatic Loudspeakers / ESLs - The Diaphragms

2008-01-10T15:47:00.000+08:00

The diaphragm is the one of the most important part if not the most important part of any ESL build. It is the diaphragm's surface that will vibrate the air and thus produce music.

Firstly, I needed a flat surface to work on that is both large enough to hold the film along with its sticky tapes (what is this for ... read on) and more importantly this surface must be free from protuberances that may damage the very fragile polyester film. So I used a glass sliding door from my walk in wardrobe. Next I prepare the sticky tape and place it all along the edge of the work surface. I mark out the perimeter of the panels that will be glued to the diaphragm on the work surface using whiteboard marker (erasable). This gives me a reference point as I go about my tasks.

Next I rollout a length of polyester film over the work surface. I make sure that there is enough film to adequately cover the references that was drawn on the work surface earlier. I also make sure that there is enough overhang on all sides of the film for me to work with I leave an overhang of 5-10cm on all sides. At this stage I just attach sticky tape over the 4 corners with moderate tension just to hold it in place.
Here is another view of the as yet, un-tensioned diaphragm. Here is a close up view from one of the corners with the sticky tape attached.
With the diaphragm and surface prepared, I am now ready to tension the diaphragm up to the designer's specification. To achieve this, I use the supplied tensioning gauge which is really a simple spring weighing scale with a piece of machined aluminium attached to the end.
First take a piece of sticky tape, attach about 2cm of it to the aluminium plate of the tensioning gauge. Next attach another 2-3cm of the sticky tape to the polyester film. Now pull the tension gauge until the correct weight is achieved, in ER Audio ESL III's case it is 800 grams. Then immediately press the sticky tape down onto the work surface and release the rest of the sticky tape from the tensioning gauge's aluminium plate. This is a really ingenious way of tensioning the diaphragm for a home builder, and simple too! The only complain is that I have 60 more sticky tape to tension all round the diaphragm. The polyester film is only 3.5 microns thick and as such very, very fragile. Do not let anything sharp come in contact with the surface. In my case, the tensioning gauge slipped from my hand and onto the surface (I was sleepy, and it was about 2-3am). It caused a rip and made half of the film unusable. Instead of getting 4 useable panels, I had to settle with just 2 panels with this sheet of film.After about 30-45 minutes of tensioning, you end up with a properly tensioned diaphragm.Now that the diaphragm is properly tensioned, I am ready to attach them to the panels. I start by applying the superglue or more aptly cyanoacrylate on to the air gap spacers. I apply two beads/channels along the length of the spacer. The first bead/channel is 2mm from the inner edge of the spacer; the second is just off the center of the spacer. The difficulty that I faced is that the cyanoacrylate dries quickly, so when I am applying the second bead, the first bead is already drying up and so I have to reapply the first bead again. You may not have realised but dry glue is no use to anyone!! This step is important so that the diaphragm is suspended properly from the inner edge of the spacer so as to avoid rattles when the diaphragm is at work.Once the glue is applied, I quickly place the panels onto the diaphragm and press down firmly to ensure a good bond. In addition I place weights onto the panels to ensure good contact as the glue dries.... I leave it for 2 hours..... 2 boxes of electrolytic caps used as weights (20 x 100,000uf @80vdc meant for another project.... watch this space)After the 2 hours are up, I use a very sharp cutter to free the panels from the rest of the diaphragm. Here is a picture of the completed panel with diaphragm. Because the glue does not spread evenly, I am left with numerous pockets of air between the film and spacer. In addition there are several instances where the film did not bond to the spacer at all. In this case I have to touch it up by dripping more cyanoacrylate on to the affected areas. This gets messy and aggravating to get right!These pictures just does not show how challenging and aggravating this part of the build is, for me anyway. Here is a picture of one of the treble panels that was just about perfect.Touching up the not so perfectly bonded area is a matter of applying more glue to the un-bonded areas. Since cyanoacrylate is very runny, I just drip some of it in the area and the capillary effect ensures that the glue fills up all the un-bonded areas. Attached is a picture of the less than perfectly bonded areas. According to Rob at ER Audio, there are more than a few ways to attach the polyester film to the air gap spacers.... 2 methods that I could have used was the super fast drying super glue method and the snails pace 24hour curing polyurethane method. On hindsight, I should have used the slower method. Why?

The super glue dries really fast, and as such you have a very short window of time from when the super glue comes out of the bottle until you place weights on the panel. And there are a lot of things that must go on in the correct sequence in between those 2 points in time, for the film to adhere to the spacers. And as my friend Murphy has it, a lot of things do go wrong.

Using the polyurethane would have afforded me much more time to get things "perfect" before the film touches the spacer. But I was impatient, so I chose the super glue method. Time will tell if I chose wisely or unwisely.... if the film stays on and does not rattle mechanically, I should be home safe. If not I have plenty of polyurethane glue and more than 40 meters of 3.5 micron polyester film left.

Next The Diaphragm Node Points.

DIY Electrostatic Loudspeakers / ESLs - Stators and Supports

2007-12-21T11:52:00.000+08:00

In the initial step of the build, you are required to glue the white and black spacers to the support structures, but this was already done for me by ER Audio. This probably saved me a day or 2. Next the steel grids that formed the stators had to glued to the support structure.Here I have the Support Structures and Stators laid out in a dry run to make sure everything fits.... and it does, perfectly. It also helps me figure out where everything goes. The picture shows the narrower treble panels. The large white bottle that you see is the polyurethane glue that will be used to attach the stators to the support structures. The glue takes 24 hours to cure and is very very strong. Good stuff. Also shown in the picture are wooden strips that will be used as pressure pads. These pressure pars will be used to push the stators and the support structures together to ensure a good bond during the curing process. I also lay out the stators for the full range panels. Notice that the screws that will transfer the +ve/-ve charge to the stators are 'brazen' in place. Again, a very elegant and simple design.There are 2 treble and 4 bass panels, in total 12 stators and 12 support structures to glue. This could get tedious. So I setup a 'production line' where the polyurethane glue is rolled onto 4 stators at one time. The polyurethane glue is rolled onto on the entire stator, this serves 2 main purposes; 1. to glue the stators to the support structure; and 2. to dampen the stator from vibrations and ringing as it is only 0.6mm thick. The Polyurethane layer applied is very thin usnig a mini paint roller. The polyurethane is applied over the entire surface on one side of the stator only. The stator side that will eventually face the diaphragm is left clean. If you are thinking that the polyurethane serves as an insulator, I cannot be sure of how well it will serve as a insulator, especially with so much voltage running through it. Best is still to avoid coming into contact with the speakers when it is in operation.

The Support structures are laid out on the table, ready to accept the stators once the glue is applied. There are in total 8 full range panels and 4 treble panels to be glued. So I do it in 3 runs of 4 each, thats 3 days of gluing, curing and waiting.... ho hum. After rolling on the polyurethane glue, I place the stators on the support structure. And the I use the pressure pad and weights to ensure a good bong all along the surface of the panelI found a way to weigh down 2 panels at a go... The next picture shows the first batch of 4 panels fully cured after more than 24 hours of bonding under pressure. While applying the polyurethane, the roller brush left many tiny bubbles, shich you can see in the picture. For the 2nd and 3rd runs, I worked out a simple brushing technique that got rid of the bubbles very effectively. You learn real quick when doing this.After gluing all the stators to their support structures, I place them all againt the wall for a dry run fitting using the channel clamps.This is how a completed side of the ESL would look like... a treble panel sandwiched by a full rnage panel on either side.A closer look at one of the full range panels fitted with the channel clamp. Remember that a panel is made up of 2 support/stators, I attached the channel clamps to the front and rear support/stators that make up one panel. As expected the clamp is very tight and also serves as a well insulated frame so that the completed panel can be handled safely. The only concern here is that because the clamps are so tight, I may damage the diapharms when I finally assemble the completed panels. Guess I need to practice this somemore before I do it for real.

ext I install the clips and copper strips. The clips will be used to connect the wires to the EHT aupply that will eventually bring electric charge to the diaphragm. Here is the clip installed on the support structure. I attach the clip first so that I know where the copper foil needs to exit the air gap spacer on the other side. The copper foil will come into direct contact with diaphragm, thus delivering the EHT charge. Before I attach the copper foil, I lightly sand the air gap spacers so that the surface is smooth and free of any adhesives that may be left over from the production process or from the previous tasks. Once done I clean the air gap spacers with some thinner. Only after I am sure the surface is clean and smooth do I attach the copper foil to the air gap spacers.This is a relatively simple task but one must be very careful with the foil as it is very thin and can snap as you fold in 90 degrees at the corners.So that's it, the stators/support assembly is completed.

The next step is the Installation of The Diaphragms

DIY Electrostatic Loudspeakers / ESLs - Out of the Box

2007-12-20T14:56:00.000+08:00

I received the LARGE box containing the ESL III components from ER Audio a couple of weeks before christmas of 2006. Happiness is when a huge package is delivered undamaged by the courier. The size of the box was a real surprise. Mentally. I was not prepared for such a large box.

I immediately opened up the both to examine the contents. Upon opening the box, I just stared at the contents for what seemd like hours..... there were just so many components. Panic started to set it... what parts are these..., what am I getting myself into..., where do I even begin...

I thought first things first, I'd do a brief inspection and an inventory check against the components list. Well everything seemed complete and in order. All components accounted for. nothing was damaged... perfect packing. During the inspection the items that caught my eyes (and hands) were the audio transformers. They are really humongous lumps of black iron making them the heaviest items in the package. If I ever need a door stop in gale force winds, this would be it!! Here they are in all their ferrous glory:

Further rummaging in the package revealed the CNC'ed support structures tucked at the bottom of the package. These support structures are made from plastic and milled on a CNC machine to generate the desired structure. These support structures will hold the stators and the diaphragm in place. They are yery well machined. Among other things, you can also see the long channel 'clips' that will secure 2 support structures that will come together to make one working panel. You will also find a roll of mylar film, wires and also tools.... yes it comes complete with tools!!

The machined support structure is the black plastic frame. The white strips that you see are the spacers that will hold the frames, stators and the diaphragm at the correct distance in relation to each other. The white spacers are glued onto the black support frame. A very elegant and but simple design.

And completeing the basic components that make up an ESL are the stators. These are the Steel Grids will be used as the the stators for the ESL. They are thin but sturdy and are finished in black powder coat.

The next Step.... I begin the build by Installing the Stators and Support Structure

DIY Electrostatic Loudspeakers / ESLs - Why and How...

2007-12-12T15:07:00.000+08:00

Electrostatic Loudspeakers or ESLs have always been thought of as very esoteric speakers to me. They seem to work on very hi-tech scientific principles only known to a few people. It was also thought of as the spekers that only the very well to do have access to. This idea was probably bourne out of the knowledge of how much it costs to buy one. My early education on the topic started thus. Little did I know that the ESLs have been around since the early1900s.

Then in 2006, I had the chance to listen to a pair of Martin Logans driven by Krells at one of the Hi-Fi trade shows. The fact that during my visit to the Hi-Fi trade show, I returned to listen to this setup 3 times speaks volumes. While seated in the sweetspot the Martin Logan ESLs did a dissapearing act, the singer was holographically projected into the room. I was really impressed. The music was, well.... very nice. Vocals were liquid, instruments were accurate and fast. The only drawback was the coned woofer at the base of the ESLs, they made the bass sound disembodied, slow and woolly compared to the rest of the music... literally.

Well after much thinking, I decided that I was not going to afford the Martin Logans on my budget. So the answer for me was going to be a DIY project. After having researched the internet for DIY ESL projects, and after reading of many successes, I felt confident enough to start my own project. While the priciples ESL are simple enough to grasp, however, I do admit that I do not have the aptitude to design and build an ESL from scratch. Through my research, I have learnt of several ESL Kit provided by ER Audio of Perth, Australia. The ESL kits comes complete with all components that would be needed to build a complete pair of ESL, with the exception of the wooden frames/cabinets, you'd need to source and build the wooden frame that holds the stators in place by yourself. Detailed instructions are provided and the support from the ER Audio is superb to say the least. ER Audio is run by Rob and Jan Mackinlay. I cannot say enough good things about Rob and Jan Mackinlay, they are both honest and helpful, eveready to offer advise and assistance at a moments notice. The fact that they are really pleasant to deal with is just a bonus.

This project is not for the novice DIYer, but the procedure to construct the kit is "foolproof". I also had the oppurtunity to discuss the ESLs with several owners that have built the kit, and all have reported outstanding reliability and support from ER Audio. What's more, all owners report that the performance of ER Audio's ESLs are equivalent to or even surpassing the ESLs commercially available today.

For my budget and my listening environment, I chose one of ER Audio's kits that bore the designation ESL III. The completed speaker is adequate for a room up to 6m x 4m. It will go down to 35-38Hz @ -5/-6db. Larger rooms would require additional reinforcements. The price of the ESL III kit by my standards, are not cheap. But its is infinitely cheaper than the of the shelf offerings by major manufacturers. The ESL III kit consists of 3 panels, 1 treble panel sandwiched on either side by full range panels.

After much thinking, I placed the order in November, 2006 or there abouts. Rob the owner then proceeded to send me the build manual, so it gave me plenty of time to get acquated in the build steps. It takes about a month to manufacture all the items and pack them. The package arrived just after christmas and I started the build almost immediately. I have now had the ESL IIIs completed for some time now. How do they sound....well... all the superlatives that you have ever heard about ESL and their inherent strengths apply here. These speakers really do need a good quality source and amplification. At the moment I am using a 100watt Yamaha AV amplifier as well as an old trusty 35watt Musical Fidelity amplifier to drive these speakers. The Musical Fidelity amplifier injects much excitement to the music, but does not have enough current to deal with the ESL's quirky impedance. The Yamaha AV amplifier is much smoother and adds a warm touch to the music, but ultimately is not fully up to the task of driving the ESLs convincingly. As such I will DIY a 200watt amp to pair with these speakers. This new amplifier is based on Pass Labs Aleph 1.2 with very good current capabilities. Stay tuned

I am doing a posthumous chronicle of the build process for the ESLs in this blog. Have fun reading.... Start Here

Jason.

Welcome to my DIY Audio journey

2007-12-12T11:37:00.000+08:00

Hello and welcome to my DIY Audio journey. Why DIY Audio and why a journey?

DIY because the chance to make something functional with your own hands is reall satisfying. And to marry this with my love for music is just a bonus.

A journey because it is my believe that there are several goals in pursuing this "hobby", it does not really have an end point. The DIY journey is full of elation and also exasperation. Sometimes you get it right most time not....

Jason