Martin Logan Cinema i, no difference with or without power adapter?

[zetagi]

Hello!

I recently bought a ML Cinema i and a pair ML Script i to complete my home cinema setup (as front i use ML Vantage). During the setup i forgot to connect a power adaptor to one of the Scripts but there was still audio but the audio level increased greatly when i attached the power supply.

A couple of days later i thought that i can check the Cinema i center speaker also. I was sure that the audio level would decrease when i removed the power adapter. But no! No difference to the audio level with or without power adapter that i notice. I have measured the adapter and it works (+15 V DC).

Are my center speaker broken? Have anybody else tried the same thing?

 

[roberto]

Hola. The time to discharge the electrostatic panel, sometimes takes time. Leave it unplugged over night, and when you are ready to listen it, play it and listen and then plug it...if there is a difference you are OK. If you can not tell, bring your ears very close to the stat panel and listen...if the stat panel is not working, there could be two things...bad stator, or bad high voltage block that bias the electrostatic panel. When you had done the tests, and the panel is not working, contact ML service dept. They will guide you to track your problem easy...happy listening!

 

[Peter Hogan]

The power adapter provides the electricity to generate the high voltage necessary for the electrostatic speaker to work. Inside the speaker, there is a circuit that converts the low voltage from the adapter to a very high voltage (in the thousands of volts) that the speaker uses. There are high voltage capacitors in the circuit that store the voltage, as well as the panel itself acts as a big capacitor to store the charge.
Disconnecting the adapter stops it from renewing the high voltage, but the voltage that is there stays until it slowly bleeds away from imperfect insulation leakage paths...this can take anywhere from a few minutes to many hours (the air humidity plays a big role in the leakage, the speakers hold a charge longer with dry air climate.
You can think of the high voltage creating the electrostatic charge like the magnet in a regular speaker. It provides the force that enables the audio signal to apply the push/pull to the speaker element, but isn't used up in the process. The magnet doesn't wear out, and if you could eliminate all the leakage paths, electrostatic speakers would only need to be charged up once, and they'd play forever.