Jazzman's new stat panels

[CharlieM]

Mavric got me primed-up with his speaker build and the insanity got the best of me so I decided to build some new stat panels for my old beam-spitter ESL's, even though my old stat panels still sound fine. The original stators are 18GA/.125 holes/40% open and my new stators are 22GA/.117 holes/51% open. I wanted to use 20GA rather than 22GA stators but I couldn't find any perf with the hole size and open area I wanted so I took a big risk and went with the thinner material.
(Sanders’ Cookbook says .020 thick aluminum is ideal but I suspect it would ring like hell). I was concerned that the thinner perf would be prone to ringing so I bonded on a couple of 1/2" square vertical steel bars to the back stator on each panel; thinking that the added mass and stiffness would help dampen any ringing. I spent a ton of money on the perf since (unlike McMaster Carr) there were min-buy and min-shipping charges. I didn’t skimp on the stator coating either: I’m very happy with how well the panel coating turned out. There are absolutely no sharp edges anywhere. After clean and prep, I painted the panels black using a Martin Senour Crossfire automotive base-coat/clear-coat system from NAPA auto parts (ouch $$). After spraying the black base coat, I applied 12 mils of the 2-part polyurethane clearcoat using the fastest drying catalyst available so the the coats would set quickly without running away from the sharp edges of the holes. As you can see in the photos, the coating turned out very well indeed. Also, rather than placing the foam tape net to the stator edges I placed the tape to overhang the stator edges about 1/16”, then wrapped 1 layer of polyester tape over the edges-- this effectively adds an additional 1/16” of insulation along the critical stator edges (these babies will never arc!). I really like the TechSpray diaphragm coating too-- it goes on wet and thick looking and takes quite a while to dry but it’s 95% volatiles so it dries very thin and it’s completely clear so you can see right through the panels. These new panels are not a huge improvement in sound quality over my original panels and I would find it hard to justify the added expense but there is a noticable difference in the highs, which seem to go higher with a bit more detail. This may have more to do with the higher diaphragm tension I used this time but it could also be the perf size and increased open area. One thing is for sure-- I didn’t loose any efficiency--maybe even gained some. I guess the iron bars worked too because I don’t hear any objectionable resonances. They sound great!

[CharlieM]

These pics show the TechSpray Licron Crystal coating applied and still very wet and the iron bars I used to stiffen the panels.

[CharlieM]

more photos

[geraldfryjr]

Awesome!
Great job charlie!
I will consider using preforated metal for my bigger panels as well and just use the plastic grate I have left for little ones. jer

[chinsettawong]

Hi CharlieM,

Very nice and impressive work.

Wachara C.

[CharlieM]

Originally Posted by geraldfryjr

Awesome!
Great job charlie!
I will consider using preforated metal for my bigger panels as well and just use the plastic grate I have left for little ones. jer

The best deal I've found for perf metal is McMaster Carr, where you can pick up two 36"x40" sheets with shipping for around $100. My stators are 48" tall though, so I had to go with McNichols Perforating and buy a whole 36"x120" sheet and pay the $80 minimum shipping fee and cutting fee-- total with shipping was around $275 -- I got the pieces cut an inch big and final cut them myself. I got some drop off left but no large pieces (I could make some bookshelf size speakers, I suppose). Also, the metal wasn't as straight & flat as the stuff Mavric got from McMaster Carr-- One piece had a crease in it, which took me a an hour or so to work down to reasonable flatness.

[kavermei]

What a great shop you have

[geraldfryjr]

Bookshelf size speakers are a great idea ,kinda like what i am working on now.
How big are your left over peices?
My little panels have a surface area of 31.6875 sq. inches.
I have found that about 60 to 90 sq. inches (2 and 3 panels) they start to match up efficiency wise and start to take over my 5" woofer.
With of course a high transformation ratio and bias voltage. jer

[CharlieM]

Originally Posted by kavermei

What a great shop you have

It's nice to have someplace to work, even if it's just an old shed like mine that I had to pour a concrete floor in.. No heating or AC either... will soon be too hot to go in there during the day.

[CharlieM]

Originally Posted by geraldfryjr

Bookshelf size speakers are a great idea ,kinda like what i am working on now.
How big are your left over peices?
My little panels have a surface area of 31.6875 sq. inches.
I have found that about 60 to 90 sq. inches (2 and 3 panels) they start to match up efficiency wise and start to take over my 5" woofer.
With of course a high transformation ratio and bias voltage. jer

Hi Jer,
I have one piece of perf metal 15" x 36" and two pieces 10" x 49" left over. Are you running your panels and woofer with some kind of passive crossover?I would like to create some small hybrids with a passive crossover but I can't imagine how to configure a passive crossover when part of the load (the ESL) is a capacitor with an impedance that varies with the frequency and end up with something that works and sounds OK.