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Old 17th December 2011, 09:49 PM   #91
fperra is offline fperra  United States
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Quote:
Originally Posted by SM7UYJ View Post
Good job, nice looking panels!

What dimensions, tension, fim etc. did you use?

Roger
Thanks. I ended up using .25 mil mylar for all the panels as the .5 mil has never arrived after 3 weeks. The vendor is refunding my money. The large panels have .125" DS and have a radiating area of 8" X 59" (472 sq in).The small panels have a DS of .063" and a radiating area of 3.5" X 59" (206 sq in). I stretched the mylar slightly more than 1.5%. I don't know what tension that equated to, but I don't think it could be stretched more without breaking.
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Old 17th December 2011, 10:21 PM   #92
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Beautiful !!!

jer
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Old 18th December 2011, 12:12 AM   #93
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Very nice looking panels. How big are they?

Wachara C.
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Old 18th December 2011, 12:42 AM   #94
fperra is offline fperra  United States
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The overall size of the big panels is 60" X 9.5". The small ones are 5" X 60". The actual diaphram radiating area is posted above.
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Old 7th January 2012, 12:29 AM   #95
fperra is offline fperra  United States
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Well two steps forward and one step back. I finished both power suppliesfor my speakers. I designed them with two high voltage supplies per channel, one for the tweeter and one for the low/mid panel. The tweeter supply is adjustable from zero volts up to 5000 and the mid supply is adjustable from zero to 10,000 volts. Here are some pictures:

Click the image to open in full size.

Click the image to open in full size.

Also,I've decided to use a dynamic woofer for the low end up to about 300 hz. The whole system will be tri-amp'd.

As for the step backwards, both tweeter panels are arcing through the but joint of the foam spacer tape at high volume levels during testing. So I will be rebuilding those. I have some idead as to how to prevent that. Tomorrow is another day.
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Old 9th January 2012, 11:44 PM   #96
fperra is offline fperra  United States
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Default A great way to insulate stators

OK, as stated earlier, my tweeter panels arced at high volume levels. The arcing occurred from stator to stator where the 3M foam tape butted together at the 90* corners. These have 2 coats of powder coat on them. I also added some coats of shellac, but the shellac didn't bond well with the powder coat so I had to remove it. After some brainstorming, I think I've come up with an excellent and easy method for putting a good insulating coating on the stators. Use 3M polyester resin (epoxy) and foam rollers. The resin is thick enough that it stays on the metal in and doesn't run off through the holes. With two coats and a little sanding between you can build up quite a thickness. and it comes out quite smooth. Here are some pictures:

Click the image to open in full size.

Click the image to open in full size.

There is nothing wrong with spray painting, but that takes much more time and material. This is a quick and easy method. Of course you would have to spray your color coat first as the resin is pretty transparent. My startors are 20 gauge and the average measured thickness with the resin coating is .074 inches.

Last edited by fperra; 9th January 2012 at 11:48 PM.
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Old 10th January 2012, 07:42 AM   #97
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Very Cool !!
I have been eyeing that type of material, But I am using wire mesh,I was wondering if for sure it could possibly be sprayed on.

I have been working on my little panels and I have almost got them to withstand all of the voltage of my power supply at 13.8Kv.
But 10kv is my safety goal as right now I have finally got to 7kv and is probably enough.

Every time I think I have done it, a hole finally burst and I have to start over and add some more coats of clear or nail polish for certain small spots.
Silicone is used at times as well and seems to be one of the best but it is a little difficult to work with at times.

It has been a pain staking process.
Because once there is a failure it does not go away or cure itself and renders the panel useless.
But I am getting there the worse part is having to wait for the coatings to cure and I believe that as they cure a while they get thinner and this reduces their insulating factor,or at least this seems to be the case.
I once Had these panels to with hold at 7.5kv before.

Right now I have only one of the panels giving me a hard time and this time it was a super small chip off of the second layer (top, black) as the first layer was white and I can see it,with a micro whole in the middle of it.

Getting to 7kv is a real challange and working two twice that is quite a feat!!!

The sharp edges have been the very worst to deal and are were most of the failures occur.
I have had to strip down some of the spots and start over, as once a path for the arc occurs sometimes it is impossible to seal it because there is now a little channel of carbon molecules from the burnt material for the High voltage to flow through.
This is some thing you cannot see.



Keep on DIYing !!!

jer
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Old 10th January 2012, 06:55 PM   #98
tyu is offline tyu  United States
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If all this sounds as good as it look.....man i like to hear thes tranfourmer on my Acoustats....Why Acoustats.. just because that what my ear Knows the most..today anyway....................Thanks for all your time an the pic...keep it coming
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Old 12th January 2012, 03:49 AM   #99
fperra is offline fperra  United States
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Well, I finished rebuilding the upper mid/tweeter panels and they came out real nice. I increases the stretch of the film to1.8% and have the bias set to 4000kv. I can go higher, but they play so loud now that there is no reason to increase the bias. This time I built them with 1" wide foam tape and extended the tape 1/8" past the stator edges. So now the active film width is 3". The new resin coating method has worked so well that I'm going to redo the woofer panels with it. I'll keep trucking and posting.

Click the image to open in full size.
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Old 12th January 2012, 05:05 AM   #100
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Very Cool !

I was wondering if you have a sound level meter can you post some figures?

I just finally got my little panels to withstand a bias voltage of up to 10kv without arcing today.
They should go higher but one stops at about 10kv and must be leaking at this point. That is about the safe limit of my supply anyhow even though it will produce 13.8kv.

Sadly I didn't have an spl meter to reference to the last time I ran them, But what a world of difference it was going from 2.8kv to 5.5kv and higher when the conditions were right.
It is going to interesting finally getting to a true 7kv to 10 kv bias.
This is alot of tension to be holding back.

Your panels are about the same width as mine but with 50 extra inches in length this about 7 times the surface area of my little panel this should be close to 9db more efficiency.

I will now Finally get to test them tomorrow for sure.


Keep up the Great Work!!!



jer
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