Full-Range Dutch ESL Project File translated

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Just FIY:
simple 9 strips per AES article, capacitance ~1500pF.
P(R1)=20W @ 10kHz, 15W @ 5kHz 3000V RMS, 9W @ 2kHz
Alex
 

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Hi Bolserst,

you mentioned the wires to be stretched by 1-2 %.

The reason why the janszen patent mentions 6% has some metallurgical background. depending of the copper alloy, elastic deformation of copper will be up to 4-5 %. You need to stretch the copper wire as much to ensure to reach plastic deformation, which starts at 5%. So i stretch the copper wire about 10%.

If you dont target plastic deformation, copper will creep by time, loose its tension and wires might start to bend, looking like a non stretched construct

Capaciti
 
Hi Bolserst,

you mentioned the wires to be stretched by 1-2 %.

The reason why the janszen patent mentions 6% has some metallurgical background. depending of the copper alloy, elastic deformation of copper will be up to 4-5 %. You need to stretch the copper wire as much to ensure to reach plastic deformation, which starts at 5%. So i stretch the copper wire about 10%.

Hello Capaciti,
You really stretch your wires 10%? Wow.
Your panels stators are about 150 cm long so you stretch the wires 15 cm?
Your wire must be very soft and very well annealed to be able to stretch this far.

The plastic deformation region starts when the unloaded wire length has increased by 0.2%. By stretching the wire so it's unloaded length has increased 2% I think I am well in to the plastic deformation zone, but I could be wrong. Referring to the attached plot, I stretch the wires to "A" and then release tension to "B" so that the wire length has increased 2%. I have several panels built using 1% length increase and have not noticed any issues with the wires losing tension.

I have had difficulty consistently stretching the wires more then 4% - 5% without breaking. The wire breaks where it wraps around the pins at either end. Perhaps you have found a way to keep the wire from breaking at these stress concentration points.


If you dont target plastic deformation, copper will creep by time, loose its tension and wires might start to bend, looking like a non stretched construct
Why would the copper creep cause the wires to lose tension?
I would think the creep would cause the copper wire to shrink a bit toward it's original unstretched length which would increase tension.
 

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The openness is very high .... might be a bit too much regarding efficiency and field homogenity. Since the PVC insulation is usually quite thick, the ´electrical´ openness is higher than it appears by optical inspection.

Hi Calvin,

Compared to the air in the gap, the PVC insulation has a very low impedance(large capacitance).
So, the electrical openness is essentially the same as the physical or optical openness.
 
Back to the question... Why do low power/low voltage resistors used?
Am I missing something?

I would guess that the resistors shown in the article were used because they work fine when playing music.
They don't overheat because of the transient nature of most music....low RMS level with peaks.
If you played 5kHz or 2kHz high power sine waves as in your simulation, the resistors would certainly overheat and fail.

The voltage rating for resistors includes many reductions to factor in harsh environmental conditions that ESLs will not experience.
I have built segmented ESLs using single resistors and the resistors did not arc or fail when playing music loudly.
But, once I started testing using high power pink noise and sine waves, I switched to using a series of resistors to keep the voltage and power across each resistor within limits.
 
Why would the copper creep cause the wires to lose tension?
I would think the creep would cause the copper wire to shrink a bit toward it's original unstretched length which would increase tension.

@Capaciti,

Ok, I think I understand what you meant by creep.
With the copper wire stretched into the plastic deformation zone and tension held, the wire can slowly increase in length = creep.

I release tension before gluing wires to stator cross bars, so maybe this is why I haven't experience problems with creep.

In any case, thank you very much for pointing this out.
I will be sure to look for signs of creep.
 
I just read the the older thread from Capaciti, i now have an even better understanding. But just be sure, i am using perf metal, wire will take place of the perf,correct? And stetching, Bolserst has me intrigued with this.
I just got home, so let me do some research on this forum and see what all what all you guys have done, with my amp setup, they will be by-amped. Any more links from anyone very much appreciated, as well as resources. thanks!
 
Bolserst,

Regarding tensioning rate two things need to be considered:

1. If you wind several wires to the gig, some will be wound loose and some more strong. If you stretch the gig by about e.g. 2 % it could be that the more loose wires wont be stretched to plastic deformation savely.
2. If you choose an appropriate copper condition, it will harden when exceeding a certain stretch ratio. I am utilizing this effect.

You are right, stretching by 10 % isnt easy and i experienced cracked wired as well. I took me some investigations and finally i found the copper quality and jig design to fix it.

As mentioned in the previous post wire stators are a very thankful design for ESL. Having solved some problems manufacturing is reproducable, reliable and low cost without compromising quality.


BTW: Bolserst, somewhere i read some thoughts of you, that an segmented wire panel should be more efficient than a perf stator.

You are absolutely right. In a nonsegmented panel (flat or bended) the amp will see full capacitance of the panel at any frequency. In order to provide bandwith up to 20000 Hz, you need to reduce stepup ratio. In additon a non-segmented panel will increase sound pressure with increasing frequency, so you need to "burn" energy in a passive network to linearize frequency response.
I did some comparisons between segmented and non-segmented wire stator. In order to target identical high frequency limit and identical lowest impedance of at least 2 ohms, the stepup ratio needed to be reduced from 1:160 to 1:100, which is a significant difference. At lower frequencies, where effiency is most important for ESL-designs, the segemented panel is more efficient by about 4dB at identical input level.

That perf stators are more efficient is imo on of the most famous rumours regarding ESL and possibly its due to the ML hybrid designs.

Capaciti
 
hi all
great thread keep it coming !

ok so far we have
1 , wire .... any pvc insulated from 1mm to 3mm od inc insulation with solid being best

2 ,segmented design makes for an easyer load and better dispersion

3, higher the better with floor to ceiling best on panel size

4, keep wire spacing similar to d/s spacing for best sensitivity

5, for full range seperate sections are best so on a panel size of say 1800mm x 360mm you would split it in half and have 1x 1800mm x 180 doing bass and 1x 1800mm x 180mm doing mid/high side by side (like capacity panels )

6, d/s spacing for full range ???

7, ds spacing for hybrid = .8 to 1.5mm depending on how accurate your panels are built

8, diaphram ,thinner is better with 3 to 4 micron ideal

9, stretch your wires between 2 to 10% depending on wire type and jig

please add to my list or point out any mistakes

cheers sheafer
 
Slr 5000,

most agreed, but:

4. always keep wire spacing as close as possible, even at larger D/S and make closer than 50% open area down to 30%
6. D/S Spacing for fullrange not more than 3mm. More will kill sensitivity significant and if you exceed a certain excursion low frequencies sound uncontrolled and boomy. A fullrange with area about 0,5qm will play loud enough if fundamental resonance is best controlled. Most designs suffer pressure due to resonance peaks consuming excursion without the impression of playing loud.
10. For lowest distortions and highest level output build your design as symmetric as possible. e.g. the D/S spacing of both stator halfs should not vary more than 0,1mm !!!!! for e.g 2,5mm D/S spacing. You can check your accuracy when looking into the finished ESL. If the membrane looks bended towards one stator its bad if it looks perfectly plane - bingo ! A worse symmetric stator design will cause the mebrane to bend up to 1mm. Easy to understand that this kills level. 2,5mm minus 1mm is just 1,5mm excursion left !!!

Capaciti
 
hi capacity
re the segmentation of the panels
the panels im currently building are modeled visually on your element x2 which i find most beutifull and have inspired me to make a wire stator esl

each panel is 2 x sections 1800mm high by 180mm wide side by side
i would like to run both sections full range down as low as possible and then fill in the bottom end with a sub

is there a theoretical ideal segmentation for this size of panel section for full range eg 1800mm x 180mm
each panel section will have 40 wires with a 2mm centre to center spacing and a d/s of 2.5mm

i was thinking 4 sections of 10 perhaps
 
hi all
great thread keep it coming !

ok so far we have
1 , wire .... any pvc insulated from 1mm to 3mm od inc insulation with solid being best

2 ,segmented design makes for an easyer load and better dispersion

3, higher the better with floor to ceiling best on panel size

4, keep wire spacing close as possible down to 30% spacing for best sensitivity

5, for full range seperate sections of the same size are best so on a panel size of say 1800mm x 360mm you would split it in half and have 1x 1800mm x 180 doing bass and 1x 1800mm x 180mm doing mid/high side by side (like capacity panels )

6, d/s spacing for full range max 3mm for minimum distortion

7, ds spacing for hybrid = .8 to 1.5mm depending on how accurate your panels are built

8, diaphram ,thinner is better with 3 to 4 micron ideal

9, stretch your wires between 2 to 10% depending on wire type and jig

10, make both stator halves as symetrical as possible ,no more than .1mm variation for lowest possible distortion

please add to my list or point out any mistakes

cheers sheafer[/

ive edited the above with capaciti revisions
 
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If you wind several wires to the gig, some will be wound loose and some more strong. If you stretch the gig by about e.g. 2 % it could be that the more loose wires wont be stretched to plastic deformation savely.

Hi Capaciti,

This is a very important point, and a detail I left out. Thanks for bringing it up.

Like you say, when winding the stator wires back and forth between pins it is very difficult to get them all wrapped with identical tension. What I do before marking the starting point for the 2% stretch is pull tension until any slack or looseness is removed from every wire. Then, mark this as the length for starting the 2% stretch. Otherwise, it would be possible to end up with some wires that did not get stretched enough to reach the plastic deformation zone. With this technique, every wire is stretched a minimum of 2%.
 
wire

Where or whom can you purchase the wire? As well, there are the resistors and values. can you kindly send a pic with 10 meg or higher to my email, as you know a picture is worth a thousand words.
The gig is and a been a problem, i was using mdf, but as i have used it for so long, i know it will splt, any suggestions?
You are obviosly a professional. I love to try different things in audio. Curious has always been my reply, so is there anyway to get better, more high res pics from your build? I did mine as step by step, still learning, want more. PM me for an email with better pics please. Other wise,have a good weekend, Mavric
 
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Hi,

the electrical openness depends very much on the thickness and the electrical behaviour of the insulation material. One cannot simply say PVC has much lower impedance and higher capacitance than air. It depends on which derivative, colour/ingredients and manufacture of the PVC. Electrical parameters may vary considerably. With regard to efficiency of the stator construction and field homogenity thinner insulation and smaller distances are preferred.

I disregard the above claims about segmented panels beeing more efficient than punched metal sheets. Theory and practise tells different. At least do I have to see the wire stator panel that beats a decent metal sheet stator in dynamic range at same input voltage range. Sonically the larger membrane area shows can be heard as a more dynamic play.
The transformation factor of the audio tranny is a direct measure of the panel´s efficiency. It translates the low value input voltage to the needed high value drive voltage.
In other words, the drive and polarizing voltages needed for a certain SPL are a direct measure for the efficiency of the panel. The lower those voltages the higher the panel´s efficiency. Typical values for wire stators are >1:75 and Vpol of >3kV, while metal stators may only need values of 1:50 and Vpol of 1.5kV. Regardless of the stator construction will a voltage driven ESL panel need some equing. This always costs on efficiency. It doesn´t matter though where I spoil the energy. Be it external eq-circuitry on the primary side of the audio tranny or be it on the secondary side ´within´ the panel. The segmenting resistors or -differently named- equalizing resistors of a segmented wire stator waste efficiency equally well as a notch-filter on the primary side.
The disadvantage of all components on the secondary side is the increased transformation factor of the audio tranny, which should always be as low as possible.
The segmentation reduces the capacitance towards higher frequencies by reducing the active stator area/membrane area. So we have a serious loss of active membrane area, hence loss of soundpressure level which is countered by a higher transformation factor of the audio tranny. But while the active membrane area may be reduced to 1/4th or less (meaning a SPL-loss of -6dB or more), the difference between a transformation factor of 1:50 and 1:100 translates to just +3dB. The impedance rises by a factor of 16 in this case, which means a slightly better efficiency wattage-wise, but since we assume an stable amplifier, that is constructed as a voltage source, only the voltage-efficiency is of importance. In this regard the non segmented metal sheet Stator is far better.
At lower frequencies the active stator area/membrane area is the same and so is the capacitance value. Therefore similar transformation factors (hence drive voltages) should be needed.
As practise shows (see Matthis) metal sheet stators still reach the same SPLs with lower transformation factors and voltages, which means that the metal sheet stator shows better efficiency even in the lower freq range. Admittedly it´s difficult to compare matters when dimensional differences of the constructions in the range of tenths of millimeters already have greater influenceon the results than the conceptional differences.

jauu
Calvin.

ps: One of the biggest advantages of low voltage ESL designs is the reduced voltage stress (voltage-gradient stress) which means less aging and higher safety margins and which allows the usage of better components.
 
Where or whom can you purchase the wire? As well, there are the resistors and values. can you kindly send a pic with 10 meg or higher to my email, as you know a picture is worth a thousand words.
The gig is and a been a problem, i was using mdf, but as i have used it for so long, i know it will splt, any suggestions?

Hello Mavric,

Unfortunately I don't have the spare time right now to put together a complete step by step build guide. In fact I'm away on business right now. It may have to wait til retirement ;)

Wire Stretching Jig strength:
If I remember correctly, it took about 30 lbs of force to stretch a single 22AWG wire, 50lbs for 20AWG. So, if your panel has 80 wires and you want to stretch them all at once it will need to withstand 2,400 lbs of force for 22AWG and 4,000 lbs of force for 20AWG. Your jig will need to be made out of metal to withstand this magnitude of force. The end blocks holding the ends of the wire will need to handle the force too. Each pin needs to handle the force for stretching 2 wires. If you want to stretch your wires you will need to build a metal jig. I used 1" x 4" structural steel tubes for the frame and 6061-T6 aluminum 0.5" x 2" for the end blocks. I got the steel from a local supplier and the aluminum from online metals.
Rectangular Tube - Norton Metals eCommerce
Order Aluminum 6061 Rectangle in Small Quantities at OnlineMetals.com

Wire sources
There are many online sources for 20-22 gauge solid copper hook-up wire.
Mouser Electronics - Electronic Component Distributor
Allied Electronics ? Electronic Parts and Components Distributor
Wire & Cable: Red/Black Zip Cord high strand count bonded wire. Stranded & Solid Hookup Wire UL 1007. PTFE Coated Stranded Wire for high temperature and abrasion resistance. Magnet Wire for winding coils ballasts and motors. Power Wire (Monster Type)
PVC Products - Jaguar Industries

For experiments and smaller test panels, you can get 100 ft rolls of 22AWG at your local Radio Shack.

Recommendation
For anybody contemplating building stretched wire stators, I would recommend starting small.
Try building a 4" x 12" panel to learn the techniques involved, and to try out different materials and adhesives.
 
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