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Old 7th May 2007, 08:52 PM   #1
bigwill is offline bigwill  United Kingdom
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Default My first ESL: works but VERY quiet

I built my first ever esl today! It even works too! I'm using uninsulated stators 8mm apart (very far I know)

The bias voltage is around 3kv (I THINK)

I have about 10Mohms between it and the mylar.

The ESL is completely silent when idle. No flapping, no clicking, hissing or buzzing or anything.

What sound it makes seems very very good indeed. It even makes bass and the treble is fantastic. Truely a full-range speaker at close range.

I'm driving it with two 6v toroidal mains transformers. They sound very good and sound like they have a wide bandwidth.

The only problem is that it is very very quiet and the amp is having a horrible time. I was expecting sensitivity to be a little on the low side but not quite THIS low.

I don't think there are any leaks. I turned off the bias supply and the speaker still made sound about an HOUR later.

Oddly enough, I discharged the diaphragm by touching its wire against the stators and the speaker still worked??

Can anyone shed any light as to why my speakers are so quiet? It would be great if they were louder since they sound so promising!
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Old 8th May 2007, 12:32 AM   #2
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Default diaphragm to stator spacing...

try a mm or two at most, one if you are not going to run FR and two mm if you are going to run FR. That will set things straight.
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Old 8th May 2007, 11:56 AM   #3
bigwill is offline bigwill  United Kingdom
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Default Re: diaphragm to stator spacing...

Quote:
Originally posted by moray james
try a mm or two at most, one if you are not going to run FR and two mm if you are going to run FR. That will set things straight.

Sounds reasonable. I have some spare panels to make another speaker with, and I'll try it.


Does anyone have an idea why my speakers worth with NO bias, and adding one doesn't make any difference?
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Old 8th May 2007, 01:21 PM   #4
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Regarding the bias: the panels are huge capacitors. The will store a charge for a long time. If you connect the supply and disconnect it they will retain the charge and play with no difference. So I assume that yo got the diaphragms charged up and then they stayed that way.
Your panels look very nice now you need some frames. Regards.
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Old 8th May 2007, 01:27 PM   #5
bigwill is offline bigwill  United Kingdom
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Quote:
Originally posted by moray james
Regarding the bias: the panels are huge capacitors. The will store a charge for a long time. If you connect the supply and disconnect it they will retain the charge and play with no difference. So I assume that yo got the diaphragms charged up and then they stayed that way.
Your panels look very nice now you need some frames. Regards.
Perhaps so but keep in mind I made a point of discharging them against the stators, there was even a little spark. They continued playing!
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Old 8th May 2007, 01:28 PM   #6
Calvin is offline Calvin  Germany
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Hi,

welcome too the community ;-)

Well, it seems that nearly each and every noob makes the same old failures, of not believing the old cracks
ESLs just work with closest proximity of the electrodes. Close means in this case very very close.

Mankind managed to fly to the moon....but they have been unable to fly to Pluto.....same is with ESLs... 1mm works, 8mm don´t.

Since the field strength sinks quadratically with every doubling of distance its no wonder, that Your panels are quiet.
Second the 3kV are a good starting point for the Bias for a 2mm distance. The voltage gradient 0.75kV/mm of Bias is just the half of what You should be able to apply without probs.

It seems a good sign, that Your speaker plays so long after the Bias is off. The longer it plays the less leakage there is. But to be honest. To really see the real effect, You have to crank up efficiency of Your panels seriously.
Btw. The reason, that they play even after ´discharging´ is simply that You haven´t dischraged them completely! The very high resistance of the diaphragm coating resists the complete dicharge for quite a long time.


jauu
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Old 8th May 2007, 01:37 PM   #7
bigwill is offline bigwill  United Kingdom
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Well it seems I have learned my lesson. Don't use ridiculous stator spacings Thanks for the help everyone!

Are 2mm spacers reasonable? As in stator - 2mm - mylar - 2mm - stator?

2mm is the thinnest double sided tape I have, should I invest in some 1mm?
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Old 8th May 2007, 03:21 PM   #8
enilsen is offline enilsen  Sweden
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Quote:
Originally posted by bigwill


Perhaps so but keep in mind I made a point of discharging them against the stators, there was even a little spark. They continued playing!
I suspect you have only drained the static charge from a small area of the diaphragm. Due to the surface resistance on the diaphragm you would probably need to discharge from more than one spot or wait for the static to migrate to where you shorted the diaphragm over a longer time frame.

2 mm spacing won't give the diaphragm much travel if you want FR with decent bass.

If I'm not mistaken when I replace the 3M foam tape on my Martin Logans I used 1.5 mm x 2 = 3 mm.
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Old 8th May 2007, 05:16 PM   #9
bigwill is offline bigwill  United Kingdom
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Quote:
Originally posted by enilsen

2 mm spacing won't give the diaphragm much travel if you want FR with decent bass.

If I'm not mistaken when I replace the 3M foam tape on my Martin Logans I used 1.5 mm x 2 = 3 mm.
I'm not too worried about the bass, as I will be building some dipole woofers to suppliment them in the bass region (4x 18" eminence sigma pro )

As for the spacing, I meant 2mm foam strips so 4mm in total. Will this have a reasonable senstivity?
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Old 8th May 2007, 05:54 PM   #10
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Default Acoustat used...

approx. 1/16 of an inch stator spacers. With the right amp even 0ne plus 0ne's can surprise you with the bass that they can reproduce.
I would get some one mm spacer material and stretch your diaphragms taught (about 2-3% elogation is good). what are the dimensions of your panels and what thickness film are you using?
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