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Old 15th August 2006, 05:14 PM   #21
tade is offline tade  United States
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lay the window screen down onto the eggcrate and then at every cross in the eggcrate use your hot soldering iron to force the screen into the plastic. Works like a charm and is easy but labor intensive.

Where can i source very thin heat shrinkable mylar and an HV bias supply? Will that aussie site ship to the US? That 3.5 micron mylar looks tempting.
I built my ESLs so long ago i have forgotten where that info is.
Thanks
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Old 15th August 2006, 08:55 PM   #22
medum is offline medum  Denmark
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Quote:
Originally posted by tade
Will that aussie site ship to the US? That 3.5 micron mylar looks tempting.

Guess so - Rob shipped to me in Denmark!
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Old 16th August 2006, 06:59 AM   #23
Calvin is offline Calvin  Germany
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Hi,

sorry to disillusionize a bit, but You wonŽt be able to build a very good ESL panel just with material You get at the grocery store At least not in German DIY-Stores -and we Germans know DIY because we spend a lot of our lifetime at those places
It is quite easy to get the material for wire stators. PVC coated wire, plastics for spacers and frames, Aluminium bars for frame construction, glues, wood for mounting frames, paints, silicone, screws and nails and some more interesting things, but You wonŽt find a good diaphragm material and it will be hard to find good material for other kinds of stators too. Since Wire stators of the kind of Audiostatics are very cheap from a viewpoint of costs, IŽd recommend to build a smaller wire stator ESl first.

jauu
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Old 16th August 2006, 07:23 AM   #24
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Hi Calvin,
I agree that we can't have everything from the local shops but no harm to at least a try at it ,

Looks like wire stator is the way to go if we insist on local hardware stores... and still get away with quality ESL build.

I had made an order for some the 6uf mylar film through mail.

If we go for the wire stator, what size do you recommand as "small" monitor? and still with ego boosting result?

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Old 17th August 2006, 07:52 AM   #25
Calvin is offline Calvin  Germany
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Hi,

since You have to partner the panel with a bass, IŽd choose the width of the panel roghly the same as the bass. The height is Your choice, depending on what You want to reach, but IŽd suggest a panel with a ratio W/H of 1/4 or more. A panel of lets say 20x100cm will work from ~200Hz on and ensures enough dynamic headroom. With smaller panels the lower crossover freq rises. I would use a panel with just 10cm width not below 1kHz.

jauu
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Old 17th August 2006, 09:20 AM   #26
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Hi calvin, guys,
Thanks for the suggestion. 200mmx1000m @ 200hz looks managable.

I got the impression that we can avoid lots of hassle if we keep the crossover point outside of congested frequency (i.e. within 100~150hz, below which the low freq starts to become non-directional,..etc etc...)... many speakers gurus recommand that, what is your view.

Does it mean that if I wish to increase the efficiency, I can parallel more then two panel of the same size with the same transformer? 200mm x 1m is about the right size to pair or quadra up in reasonable space...

Another question, has there been many "true" single fullrange ESL working successfully from 60hz to 30khz?? I mean can they play matallica type of music??? or what type of music can be played???

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Old 17th August 2006, 09:55 AM   #27
Calvin is offline Calvin  Germany
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Hi,

You might use the panel down to its ground resonance. Something ML has done. The pros are:
- easy crossover design -just a high Q-second order Highpass
- high output and
- largest possible bandwidth
- low crossover point acoustically and much higher electrically!
- use of highest mechanical tension -> stability and efficiency
The cons:
- to my experience -and IŽm not alone- the high Q of the resonance (slow decay) is sonically detectable like kind of a ŽfootprintŽ
- the distortions are quite high.
- You have to control the mechanical stretching of the diaphragm quite carefully for low tolerances

The pic shows the results with my panel (ML Sequel size) and a comparison to an original ML Prodigy panel
Click the image to open in full size.
Even though You get close to perfection measurement results it sounds better when the panel is not used down to its ground resonance. Now I use a filter that cuts off @350Hz acoustically.

You can increase efficiency by paralleling panels, Yes, But(!) the impedance curve drops and might reach very low killer levels.
Too the bandwidth of the Trannie-Panel combination sinks. You might not reach 20kHz any more.
If there are series resistances to correct for the freq-response in the HF-region the freq-response will drop even more.
IŽd prefer to build a single panel rather than paralleling several smaller ones.

And Your last question: There are a few...and No!
For high SPL purposes build a Hybrid! Much better much easier and more compact!

jauu
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Old 17th August 2006, 10:42 AM   #28
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Calvin,
I have to chew on what you had just said... as I am very new to this

Do you mean that 200~250mm x >1000mm panel, (Taller the better) @200~300hz is about as far as we can ask for with (compromised) good results and without excessive complications?

BUT I still have to limit the size of the panel within the dimension of "bicycle tyre tube stretching table". Or is there other simple stretcher that I can use?

And I'll just have to increase the tension and bias oltage to raise the SPL.

This may sound stupid but I'll ask anyway... Can we series some panel without ill effects? Since capacitance reduced when connected in series...?

AND do we still need to measure the tension of the diapharm?

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Old 17th August 2006, 04:14 PM   #29
Calvin is offline Calvin  Germany
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Hi,

the prime goal in ESL construction is efficiency.
To get high efficiency You can:
- build big panels
- use smallest stator/diaphragm distances (d/s) possible
- use the highest possible voltages
- use high mechanical tension --> high ground resonance --> high dynamic stability

A d/s of ~1mm is still practical to handle and allows for frequencies down to ~200Hz. With this distance the diaphragm should be supported every 70-100mm to not to be drawn into the stators.
Stretching as hard as possible, You can get ground resonances from ~150Hz with a 3”m film to 250Hz with a 12”m film. Stretching hard raises the stability treshold and the efficiency significantely. Having the crossover not lower than one octave above Fs means a crossover point between 300 to 500Hz. When You measure the distortion You will see that they rise -rather shoot up- below 300Hz anyway. Additionally installing the panel in an open baffle You have to account for phase cancellation. So 300Hz is a good starting point for a panel (150Hz Fs) of handeable size. You can still use a passive crossover to equalize the phase cancellation.

One of the biggest mistakes of ESL-Noobs is, that they try to get down in frequency range as low as possible.
But You loose on nearly every important parameter in doing this!

You donŽt necessarily need to tension mechanically. You can use heat treatment very well, but You will have to support the diaphragm with spacers closer apart than with high mechanical tension.

You can upsize the tyre stretcher by cutting the tyres and gluing together as many as You need.

Connecting ESLs in series....I have to admit that I never had that idea! A symmetrical ESL could be considered as two series connected capacitors.
The problem is that the driving signal voltages for each panel would be halved, so efficiency wouldnŽt be raised as with parallel connection. Since the capacity of this arrangement is halved too, the impedance the amp sees would be raised. While this could be desirable in the HF-range the impedance of the single panel/tranny is quite high (and doesnŽt give the anp any stability problem) in the mid-band. A positive effect could be a rise in the upper bandwidth limit. But You need a higher transformation factor for the needed higher signal voltages which will impose the state of affairs again.

jauu
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Old 18th August 2006, 02:25 AM   #30
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Hi Calvin,
Thanks for the in-depth, More questions

Quote:
A d/s of ~1mm is still practical to handle and allows for frequencies down to ~200Hz. With this distance the diaphragm should be supported every 70-100mm to not to be drawn into the stators.
Do you mean support by dividing the panel by strips of 1mm thk insulators of 70~100mm apart laid vertically on both sides of the diapharm? or using "dot" double-sided tape (or "dot" insulators) spread in random at spacing of 70~100mm from each double-sided tape point?

Quote:
You donŽt necessarily need to tension mechanically. You can use heat treatment very well, but You will have to support the diaphragm with spacers closer apart than with high mechanical tension.
I read from other threads that tension is limited when heat stretch, mechanical cna stretch harder but film will sag over time... can we mechanically stretch the film then heat shrink the film and get the advantage of higher tension and no sagging in the future?

The series connection will have to wait until I build a high output voltage swing power amp before I can try em on...

Quote:
You can upsize the tyre stretcher by cutting the tyres and gluing together as many as You need.
Why didn't I think of tha

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