So, I'm making ESLs (yay) for my room. The acoustics in my room suck, but a discarded roll of wall-to-wall carpet will fix that =)
The main things I worry about these days when designing an ESL panel are bass and arching. So I modified my design (note this is my plan of action; it's not tried or tested):
A = 1" acoustic insulating foam with 1" clearance from frame
D = diaphram
F = frame
G = 3/16" rubber insulator gasket
G2 = 3/16" rubber insulator gasket with two 1/2 inch sections removed opposite eachother
S = stator
C = cloth cover
R = conductor ring with wire attached to the outer edge
-= original =-
|A| |C| |F| |S| |G| |D| |R| |G| |S| |F| |C|
-= new and improved =-
|A| |C| |F| |G| |D| |G2| |S| |G| |D| |R| |G| |S| |G2| |D| |G| |F| |C|
Assembly:
1) Stretch the three diaphrams on three separate bike-tube jigs
2) Coat one of the diaphrams on both sides with Elvamide (http://www.quadesl.org/Area_51/area_51.html or http://www.polymart.com)
2) Spray adhesive on one side of the Gs, G2s, and the conductive ring
3) Attach each of two Gs to a frame, each of the remaining two Gs to a stator (smoother side), and each G2 to a stator (the bumpier side), making sure they all are aligned
4) Attach the conductive to one of the Gs attached to a stator
5) Place the pieces/layers as shown above (without the A and C)
6) Make sure everything is aligned and clamp the frames on each corner (or more; I used 1/8" thick aluminum as my frame, so I'm not worried about the pressure being uneven)
7) Drill a hole in the center of each corner of the assembly, taking care to not to dislodge the clamps
8) Bolt each corner, tightening until the inner side of the stators are 7mm apart
9) Remove the clamps
10) Glue/seal a small hose to each of the openings the gaps in G2 created
12) Fill a balloon full of N2 or your favorite innert gas
11) Kink one of the hoses and slowly pump out the air for one side of the assembly until the diaphrams almost touch the stator (try to get it as close as possible)
12) Attach the balloon full of N2 to the hose you used to pump the air out of the chamber, and slowly/carefully refill the chamber with N2 (you don't want the diaphrams bulging outwards)
13) Unkink the other hose, flush the chamber with N2 and kink both hoses
14) Repeat steps 11 - 13 on the other chamber
15) Remove one hose at a time, filling the hole in the gasket with silicone sealant
16) Let sealant set/dry
17) Cut diaphrams from jigs at the edge of the gasket and blow-dry so the jaggedness goes away
18) Finishing touches go here. For instance the cover cloth and the acoustic foam with 1" spacers, along with a baffle if you so wish, a box of some sort, or a stand/mount
Notes:
- One could attach two valves to each chamber instead of two hoses, and leave them in.
- Flushing the chambers is not necessary, but it will increase the concentration of N2, which will reduce the chance of arching.
- Since the stators are so far apart (most bass ESLs are a max of 6mm) and there are three membranes (3 times the weight), the bias will have to be greater. Hopefully the resultant sound have richer bass while keeping the highs crisp.
Edit: I have a full parts list with online distributors, part numbers, prices, and so forth I can post if anyone wants it. It's costing me around $100 per 18"x36" ESL. It is the original list, but plenty of diaphram and gasket material is already included, so it should work fine.
Enjoy!
The main things I worry about these days when designing an ESL panel are bass and arching. So I modified my design (note this is my plan of action; it's not tried or tested):
A = 1" acoustic insulating foam with 1" clearance from frame
D = diaphram
F = frame
G = 3/16" rubber insulator gasket
G2 = 3/16" rubber insulator gasket with two 1/2 inch sections removed opposite eachother
S = stator
C = cloth cover
R = conductor ring with wire attached to the outer edge
-= original =-
|A| |C| |F| |S| |G| |D| |R| |G| |S| |F| |C|
-= new and improved =-
|A| |C| |F| |G| |D| |G2| |S| |G| |D| |R| |G| |S| |G2| |D| |G| |F| |C|
Assembly:
1) Stretch the three diaphrams on three separate bike-tube jigs
2) Coat one of the diaphrams on both sides with Elvamide (http://www.quadesl.org/Area_51/area_51.html or http://www.polymart.com)
2) Spray adhesive on one side of the Gs, G2s, and the conductive ring
3) Attach each of two Gs to a frame, each of the remaining two Gs to a stator (smoother side), and each G2 to a stator (the bumpier side), making sure they all are aligned
4) Attach the conductive to one of the Gs attached to a stator
5) Place the pieces/layers as shown above (without the A and C)
6) Make sure everything is aligned and clamp the frames on each corner (or more; I used 1/8" thick aluminum as my frame, so I'm not worried about the pressure being uneven)
7) Drill a hole in the center of each corner of the assembly, taking care to not to dislodge the clamps
8) Bolt each corner, tightening until the inner side of the stators are 7mm apart
9) Remove the clamps
10) Glue/seal a small hose to each of the openings the gaps in G2 created
12) Fill a balloon full of N2 or your favorite innert gas
11) Kink one of the hoses and slowly pump out the air for one side of the assembly until the diaphrams almost touch the stator (try to get it as close as possible)
12) Attach the balloon full of N2 to the hose you used to pump the air out of the chamber, and slowly/carefully refill the chamber with N2 (you don't want the diaphrams bulging outwards)
13) Unkink the other hose, flush the chamber with N2 and kink both hoses
14) Repeat steps 11 - 13 on the other chamber
15) Remove one hose at a time, filling the hole in the gasket with silicone sealant
16) Let sealant set/dry
17) Cut diaphrams from jigs at the edge of the gasket and blow-dry so the jaggedness goes away
18) Finishing touches go here. For instance the cover cloth and the acoustic foam with 1" spacers, along with a baffle if you so wish, a box of some sort, or a stand/mount
Notes:
- One could attach two valves to each chamber instead of two hoses, and leave them in.
- Flushing the chambers is not necessary, but it will increase the concentration of N2, which will reduce the chance of arching.
- Since the stators are so far apart (most bass ESLs are a max of 6mm) and there are three membranes (3 times the weight), the bias will have to be greater. Hopefully the resultant sound have richer bass while keeping the highs crisp.
Edit: I have a full parts list with online distributors, part numbers, prices, and so forth I can post if anyone wants it. It's costing me around $100 per 18"x36" ESL. It is the original list, but plenty of diaphram and gasket material is already included, so it should work fine.
Enjoy!