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Oliver Acoustic Research AR-94 specifications
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Introduction

I would like to thank all who work on The Audio Circuit website. The most ESL information is from this nice site.

The curved ESL isn`t my first ESL. I build four ESL speakers before I`ve building these speaker. The experience I developed when building these was very usefull when I build my first curved speaker.

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What you need

These ESL is making of the following materials:

  • 2 x Aluminium perforate plate 50cm x 20 cm x 1mm
  • M3 Foam tape Scotch 1,5 mm thick 19mm width
  • Copperband 5mm width
  • Mylar 6 µm thick
  • 2 little screws M3

Bend

The perforate plate is flat, if you buy it on any shop. Now you have to bend it. I tought it over one day and night but it was on the Internet that I found the solution! There are very good machines with 3 rolls. WithI such a machine you can bend thin plates in any radius you need.

After some telephon calls, I found an locksmith who could help me with such a machine. I told him that I needed an height of 2 cm in the middle of the plate. For 15 Euros (around $13,50US) he made me a nice curve on both plates. Both plates have the same radius. In reality the inner one need an little bit lower radius, but that's not a problem. If you put both plates together you will have a little mechanical tension.

Paint

The important work on the ESL, built with perforate plates is to eliminate all burrs on both sides from the plate. I do this only with a hand drill without any additional machinery. After this elaborate work you can paint the plate with plastic paint. I used only one grey color but I think it`s better to use two different colors. this woill make it a lot easier to distinguish the various layers. I painted both sides three times or so. At last I took an spraycan and gave the panels a nice black color.

When the paint is dry it can begin! At first we drill a hole on the side of the plates to put the screws in. So we have the contact to each plate. Now we can stick the 19mm foamtape on the edge around the plate. After this we stick the foamtape in the middle of the plates as shown in the pictures. I cut the foam tape strips for these to 9 mm width.

Mylar

Now you have to place the Mylar between the curved spacers and plates. That's not easy. I spent some days thinking on this problem...

(Today I work on an text to place it here... will be updated. :-)

Test

BEWARE OF HIGH VOLTAGE!

When the curved ESL is ready it will work really nice. I use a voltage around 2000 V. The sound is very clear and loud and you will have an good room dispersion. The ESL sound dispersion is for my opinion much better compared to the flat panel ESL with his little sweet spot. (Sorry to all how build nice flat speakers)

Bass

You can`t never produce enough bass with an curved ESL. The best way is to combine these curved speaker with an little normal cone speaker. I bought two sheets of wood measuring 20x80 cm and built this little speaker. It is a combination from an ESL with a cone speaker.

Today I work on the electronics. My amplifier doesn't have enough output power. The audio transformer I used is a valve push pull type from Hammond.

Future

In the future I want to build an bigger curved speaker. To build an ESL is a nice experience and it allows you to klnow to learn more about different materials and electronic components. Kind regards, Sven May

Pictures