Martin Logen's ESL Sequel II Laboratory and other tests

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Avigdor Jakubinsky

Aug 21, 2019, 1:57:32 PM8/21/19
Hi all ML owners,

I have had been usin my Sequel II - Martin Logan's fantastic ESLs since Aug. 1990 !!! I had my first issue with one panel only after 3 months of use, (Balance issue) I noticed that the sound "moved" to the left area of the speaker yet in almost full db., I have contacted ML and got a brand new pair of panels shipped by airplane to Israel free of charge, after installing the new pair the speakers worked 20 years without any degradation signs until recent year after moving to my new home by the sea-shore... that the sound got weaker and weaker from the static section yet evenly. I have read your comments in this forum and I am going to check several parts, btw, after air-conditioning the room the sound level from the stat gets much better.

1. Power supply (Required HV voltmeter range that is not a common one)
2. Capacitance of the Hi frequency crossover's capacitors in each speaker.
(I hope the value is registered on them)
3. The "corona" damages mention before.
4. I used to work for CISCO SYSTEMS back then, and remember using a static
Electricity measuring device, I may borrow one and hope to get some
Information out of it and for your information, if you unplug the AC and the sound immediately drops it means that the problem is more likely has to do with the level of the power supply voltage.

Please contact me if you would like to share your experiences hereto.

Best Regards

Avigdor Jakubinsky

Peter Wieck

Aug 21, 2019, 4:07:25 PM8/21/19
Three things:

a) ES Speakers, as a class, really do not like humidity.
b) ES Speakers, as a class, really do not like polluted air, especially particulate pollution.
c) AC, properly sized in capacity, reduces both significantly.


i) DO check HV level.
ii) DO check the connection(s) to the Mylar panels.
iii) Exceedingly carefully: Do clean the panels and connections.

Particulates build up on the Mylar panels as many of them can carry a charge - and, in part, how electrostatic air cleaners work. They will also build up on the connection(s) and cause corrosion. Add humidity to the mix, and things get infinitely worse.

Put another way, if one wants planar speakers in any climate that is not either naturally dry *and* free of particulates, or maintained as such 24/7/365, go with Maggies.

Peter Wieck
Melrose Park, PA
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