It's Alive !!

[CharlieM]

Hello everyone,

After months of toil and a few setbacks my ESL's are now ALIVE! (pics are attached)

I still have to build grills and an EQ for the dipole rolloff but all else if finished.

I fired em' up on July 4 with [Goddess] Diana Krall singing Nat King Cole's "You're looking at me". Finally I have speakers worthy of Diana who now sounds as good as she looks :-)

The design uses a 10" Aurum Cantus MkII woofer in a 4ft3/9ft transmission line cabinet with a 12' x 48" esl panel. The panels are 18 gauge steel perf stators with 6-micron Hopstephan diaphragms assembled with 1/16" foam mounting tape. Trannys are 100:1 and bias supplies 2.5kv, both purchased from Russ at Just Real Music. Overall speaker dimensions are 15" wide x 67 1/2" high x 21 1/2"depth. I am using a DBX 223 active crossover with 24 db slopes and adjustable crossover points feeding a pair of Carver TFM 25 power amps.

The bass cabinet design was a dilemma since I wanted a 10" woofer in a transmission line and I wanted the woofer under the esl panel. The challenge was cramming all that box volume into a reasonable footprint. After much mental anguish and ten design iterations, I opted to extend the cabinet upward, behind the esl panel. This necessitated making the front edge of the bass cabinet a “V” shaped beam splitter to divert the esl’s backwave out the open sides of the speaker.

I have no means to compare my beam-splitter design with open dipole designs in a side-by-side listening test so I can only wonder if there is an imaging tradeoff or possibly other sonic differences (aside from bass). I have no way to know—but I can say that the bass is both lower and tighter than any speaker I've owned and I'm just stunned by the performance of the esl panels. My concerns about the panels being too small were unfounded, since they can in fact produce ear-splitting volumes without distortion.

I'm sure all of you here can remember first hearing your esl speakers and being amazed by their stunning speed and neutrality. I can't wait to get the EQ circuits built and see what effect that has. I have Delta Cad drawings if anyone wants them but be forewarned that that the boxes were exceedingly time-consuming and difficult to build.

Special thanks to GM for pointing out the futility of my original transmission line design.

To my new friends Few, Sheldon, Moray and Calvin:
I couldn’t have done it without you guys-- thanks for all the advice, encouragement and immoral support :-)

Charlie

http://img357.imageshack.us/my.php?i...yesl022ef1.jpg

http://img78.imageshack.us/my.php?image=myesl012ha3.jpg

[studiotech]

You did a great job!

How far is the angled wood behind the panel? I would think that you might get some weird reflections....You may want to try some good acoustic absorbtion material back there to see if it is an improvement. Either way, I'm sure they are great and you should be very proud.

Greg

[CharlieM]

The apex of the "V" is 3 1/2" behind the rear stator and the wings on the esl's frame/baffle extend 3" behind the rear stator-- so, if we assume that a pressure wave behaves like a projectile striking a surface (and I don't know if we can make that assumption) then the wave rebounding off the beam splitter should go straight out the side, clearing the baffle frame with a 1/2 inch to spare.

In retrospect, it woud have been smart to build the stators first and do some testing with beam splitters before committing. As it was, it took months and a lot of frustration after purchasing the trannys, power supplies and stator material to get those components so I went ahead and built the cabinets while I waited.

I'm considering removing the panel from one speaker and comparing its sound (in free air) to the other speaker. If I do that, I will post my impressions.

thanks for the compliment on the build

[moray james]

sounds like great success wth the panes I knocked on wood and crossed my fingers. You and your buddy pulled a great white rabbit out of the hat and that was by doing an excellent job of it. Will be interested to hear if you do the free air comparrison between the two panels. If you ever open the one I was going to suggest a layer of pet tape with acrylic adhesive across the tack line and you can forget about it ever arcing, simple and fast to do. I am very inpressed with the look and the overall ratio it all works so very well. Fantastic inspiration to all the others who wish they could, you have shown them that they can. By the way you don't look anywhere near happy enough in your picture having done such a bang up job. The guys at the speaker store will not be wanting you hanging around the shop anymore (bad for business). You might have them over for a brew and a listen.

[Few]

Charlie--
They really look great, although the center channel in that first photo doesn't quite match the left and right channels. After all the time and effort you've invested you should be very proud of the outcome. I think you'll find that once you compensate for the dipole roll-off you'll fall in love with them all over again. At what frequency are you crossing over from woofers to ESLs?

I haven't done a comparison between free air ESLs and those mounted in front of beamsplitters, but Roger Sanders built panels of both varieties and apparently was satisfied enough with the beamsplitter design to include it in his book.

Well done!

Few

[CharlieM]

Yeah, that old center channel in the first pic looks pretty worn out, huh?

I've got the X-over point at around 350 hz right now but the DBX is infinitely adjustable so I can play around with it and I'm sure I will.

When I run the signal path thru my old Audio Control 10-band graphic eq there's a definite improvement with the 480hz and 960 hz faders boosted up (compensating the dipole suckout)-- the only problem with that is that my graphic eq has some dust conatmination I guess because it also drops the volume on the left channel and crackles some. I will have to teach myself to build a printed circuit IC and then build a dedicated EQ for the dipole rolloff.

It's crazy how I can't stop playing different cd's just to see how my favorites sound thru these speakers.

Sanders' book gave me the idea for the beam splitter cabinet, allowing the large box volume needed for the 10" woofer TL. Although Sanders' beam splitters use both the cabinet and a room wall as the reflecting surfaces, his are shown placed really close to the wall in a room corner-- there has to be all kinds of resonances bouncing around there so I figured if that sounded OK, mine probably would too.

I'm intrigued by Greg's suggestion to try placing some acoustic dampening material behind the esl panel-- even if there are no adverse resonances from the beam splitter per-se, there could be an advantage to dampening the backwave which would otherwise bounce off adjacent wall surfaces back to the listener. I've heard that one feature that made the unique Beveridge esl speaker sound so good was that its backwave was totally absorbed by stuffing in the cabinet.

While I would like to know how my speakers sound next to open dipoles, I don't want to get so wrapped up in "what if's" that I forget how good these speakers already sound, as-is.

When the NEW wears off enough that I can make myself quit shoving cd's in the deck, I will probably remove one of the panels and do the free air listening test I mentioned earlier and also perhaps place some pillow stuffing behind the esl panels to see how that sounds.

Chaz

[ktuuri]

Glad to hear you got them up and running and I gather, running very well.
Beautiful work you did, gives me hope. I like to listen at night with the lights out, but with them I would have the lights on, some nice eye candy there!

[CharlieM]

Ktuuri thanks for the compliment- I had some woodworking experience but I didn't know anything about building ESL's when I started the project in January. I had Sanders' book but the electronics were and still are intimidating. There were times I wished I hadn't started it (I bet many here went through that too). Some great guys here kept encouraging me and helping me solve the build problems-- still have to design and build grills and an EQ.

Tell me about your project-- aren't you building some speakers now?

[ktuuri]

No not yet. But I will, just living through others for now.
Got to many things on my plate right now, gota get busy and take care of them.
You say you didn't know anything about ESL until Jan.
I guess some are a quick study.

Keep us updated.

[AndrewT]

Now that the lower bass speaker has been added to the Hybrid, would you want to review the bandwidth of the Hybrid?