Aerius i - Panel Age

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kalali

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I have a pair of Aerius i speakers, model year 1998. I've noticed a slight loss of clarity in one of speaker panels that is really noticeable when I listen to the speaker by itself. The panels are clean with no dust or anything on them but looking closely through the mesh holes, I did notice some gray spots on the mylar in the speaker that sounds a little less crisp. The "good" speaker has a completely clear mylar. Is this part of the normal life expectancy of these panel speakers? What about the electronics? Anything can be done aside from a complete replacement of the panel?
Thank you all.
 
I'm surprised someone would claim their almost 20 year-old 'anything' are completely clean, but let's put that aside for now.
The gray spots on the mylar aligned with every stator hole opening are normal, and they're due to migration of the graphite coating which is manually applied during assembly. But there should not be obvious differences of these spots between two panels from the same pair. However, the 'spots' might be a red herring in your case, and you should be looking for the typical age-related slow failures:
a) ESL panel slipping down and hanging from the connecting wires
b) ESL sandwich separating due to loss of clamping force of the shrinking weather stripping, causing the copper charge strip to loose good connection to the mylar
c) charge strip corroded
d) HV supply problems

Let's rule out some simple things: Play the problem speaker and notice if squeezing the ESL sandwich together by hand at different points makes it sound different, or if it's louder from certain sections of the ESL, or if it causes (or reduces) faint squeeking (indicating a HV leak). If you get no changes, move to the next step:

Let the panels stay unplugged overnight, and swap the panels L to R, and check if the problem follows the ESL panel or stays with the power supply, and report back. While they're partially apart, tighten up every single screw inside and outside.
Good luck!
 
Tosh, thank you for your detailed response. I'll do what you suggested and report back. Regarding step 2, did you mean literally remove and swap the ESL panels or swap the speakers as a unit as if I'm swapping the channels? I guess I didn't quite follow your reference to the power supply, e.g., speaker power supply or power supply as the signal (source) supply. Thanks again.

Edited to add: As for "cleanness", I only visually checked the panels and they "appear" clean. Are there any additional steps I need to take to ensure the panels are actually clean, outside of a complete removal and literally washing them by hand? I did see a video of someone washing them in a shower but I'm very leery about having to go that far.
 
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There is a high-voltage power supply in the cabinet that charges up the mylar, and that circuit is independent of the audio signal.
Right, step 2 is to dismount the ESL panel itself from one cabinet and swap it to the other cabinet to check if the low output problem is in the ESL panel or if it's a problem with the HV PS in the cabinet. You might need to study up on how these old MLs are held together if you get that far.

Dirt and bug pieces get embedded in the porous foam spacers, causing HV leakage, and can be very hard to remove (and an actual shower is a last resort to attempt to dissolve and flush those out). A proper vacuuming procedure would be to put on your magnifying glasses and use a soft brush attachment to vacuum every single square inch front and back, especially around the spacers and outside perimeter of the ESL panel. Brushing with a soft clean brush is not harmful.

What I think you should do first is familiarize yourself (by placing your ear to the ESL in different places) with the faint squeeks that a normal ESL panel makes when charging up, and then while still listening with your ear up to the ESL, squeeze the ESL sandwich together to see if the HV noises change. (The amp should be off for this, so you're not listening to its noise.) If the noise changes a lot when you squeeze it, that indicates that the HV charge is moving around, and that for some reason the full charge is not reaching the whole mylar.
 
Thanks again for your input. I tried squeezing the front and rear "screens" together on the suspect panel and couldn't hear a difference. Now, I don't know how much this matters but looking at the serial numbers for all four pieces; both pairs of electronics and the ESLs, the suspect panel is not in the same batch as the other components. More specifically, on the "bad" speaker, the panel is about a year and half newer than the other panel. All other three components are made in the same month. So either the panel was replaced at some point or it was delivered like that from the factory. In must add the main difference between the sound quality (and volume) is in the lower part of the panel right above the woofer area. I'll continue troubleshooting by trying to isolate the issue between the panel and the power supply. Thanks again for your input.
 
Possibly one panel was exchanged under warranty...

When listening for the difference between the two panels, are you playing only the ESL portions (and leaving the woofers disconnected)? And the weaker panel is not outputting as much sound in the lower portion of the ESL panel, but in the upper portion it is normal?
If so, it seems you have a problem with the HV charge either not reaching the lower part of the panel or being bled off (leaking away) faster than it's being charged up.
But it also sounds as if the HV PS is functional in both speakers, so you would not need to swap ESL panels L to R to continue the diagnosis.
Since the three soldered wire connections to the ESL sandwich are located in the lower right edge (viewed from the front) of the panels, I think you should firmly squeeze the panel together by hand in the area of that right-hand edge to see if higher clamping force can cause the copper charge strip (which runs along the right edge only) to make better contact with the mylar.
 
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I read that after 10 years the panels can be heard to deteriorate, these ones are almost 2x that so its just wear .

But swapping panels narrows down problem to panel or electronics.
 
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