Infinity Servo Statik 1 mid range panel

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Hello.
Can some one please share any photos and info of Infinity Servo Statik mid range panels inside. The conductive layer pattern, resistivity, membrane coating and resistivity, plastic electrode thickness and dimensions. It is very interesting as this details looks very specialised for mid range.
Thanks.
 
Thanks. This is one of the best references, but threre is no internal design of midrange panels. A lot of articles and conversations are dedicated to their perfect sonic qualities but some factory production problems. My interest is some wider: the conductive layer structure, vertical or horisontal segmentation and resistivity, stator to membrane spacing.
 
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Since the response to this topic has been light, I'm going to speculate a bit and give some opinions. I don't have direct experience with the Servo-Statiks though.

There are discussions on Audiokarma and in Stereophile's reviews about reliability problems with the "midrange" panels. The Stereophile review also talked about replacing those panels. Seems a bit odd that they were pushing ease of panel change, unless they knew they were flaky. The Infinity explanation that a limited number of SS-1A's had chemical composition problems, doesn't seem to line up with reports of midrange panel failures on the previous model. It may have been another problem, but was probably not the only problem.

Infinity Servo-Statik 1 loudspeaker What If You Lose a Midrange Panel? | Stereophile.com

Infinity Servo-Statik 1 loudspeaker J. Gordon Holt October 1975 | Stereophile.com
"plus the bad reputation gained by the previous-model Servo-Statik (the SS-1) and some persistent reports of continuing problems with midrange speaker modules"

Infinity Servo-Statik 1 loudspeaker Manufacturer's Comment | Stereophile.com
"we had recently discovered defects in the chemical composition of our grid laminate which would cause subsequent deterioration of the modules."

What's called a "midrange" panel was nearly full-range on the bottom end. The lower crosspoint was stated as 70 Hz for one iteration and 100 Hz for another. If you want a true midrange panel, you can likely do better than the design they used. Theirs would have unnecessarily low resonance and large spacing compared to a midrange-optimized one.

Something else that's interesting is that the tweeter panels seem to have almost never failed. They are based on the Janszen designs, which are similar to Acoustat's panels, which also almost never fail.

For its time, the Servo-Statik had a pretty large membrane area. That was likely the largest influence on the perceived midrange performance. There's not much else in the midrange panels that seems worth replicating given the reliability problems that seemed to plague them.
 
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Thank you, but there is some questions about midrange panels phisics i still have.
Was the internal conductive layer tree-like with central cord connection? Do some relations between difraction and dispersion was in mind for some specific frequencies and this influenced on panel's grid with such wide strips?
 
I have not seen anything that leads me to believe the midrange panels were doing anything fancy when it comes to resistance of the conductive portion or patterning to affect dispersion. An innovation of that magnitude would likely have been a marketing point that would have been highlighted.

If the midrange stator conductors were of uniform low resistance, their pattern would have little influence on dispersion. Whether they were horizontal or vertical, driven from the side or center, etc. they would combine acoustically to produce the same output at the frequencies they were running.

At that time, most electrostatics had problematically low sensitivity. With constant low resistance conductors in the stator, I can only imagine dispersion shaping patterns that would sacrifice output. It seems like an unlikely approach for the time.

If you know or have heard of something that contradicts these ideas, please share that, as details about Servo-Statiks seem hard to find.
 
As for the stators, such information was confirmed:
H: 15 1/4" (38.735 mm),
W: 11 1/4" (285.75mm),
Thickness 3/8" (9.525mm).
Calculated by photo slots H: 1/8" (3.175mm), W: 2 3/8" (60.325mm) (two raws of slots with 2 3/8 and 2 raws of slots 1/8" wider).
The vertical distance between 13 slots is 3/8" (9.525mm). So 25% open area.
Membrane conductive layer from one side (looks like made with magnet tape making process). No information about resistance.
The conductive layer unknown with some base with yellowish powder on it and impregnated in plastic body, insulated by orange transparent plastic film near 1/32" and separated from membrane by 1/32 white plastic frame.
The conductive path looks like the perimeter loop with horisontal lines from border to border.
ESL.jpg
 
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Interesting.

From a design standpoint, the free span of the diaphragm is important. From your measurements, sounds like that is 2 3/8" by about 14". Along with tension, it determines diaphragm resonance and panel stability (keeps diaphragm from being sucked into stator). It's typically limited in one direction to less than 100x the diaphragm-to-stator distance, which seems in agreement with the 0.32" spacing.

Transparent orange insulating film is often Kapton. I don't know if it's what they used, but Kapton would not typically be used now. The volume resistivity of Kapton is too high for stator insulation.
 
Some addition. Membrane coating more looks like coloidal graphite instead of advanced magnet tapes technology.
My impression about infinity midrange panels is that is 2D version of Beveridge 3D very early version from patent with amandment on constant charge version.

Infinity_SS1_Electrodes.jpg
 
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Interesting information was confirmed.
This is panels of late production. The conductive path of stators is silver loaded paint and it is looped. The orange film is Kapton. The surface resistance of membrane coating is 300K.
So this is very close to Quad 57 in principal.
 
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