Bi Amping Electrostatics issue

helipilot

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I have a pair of Martin Logan Ascent i electrostatic speakers. Since I purchased them I have had them bi wired to two Crimson 630C mono block amplifiers. Recently I got my hands on another two 630C's and decided to try bi amping them.

Everything works fine but I have an issue when I switch off the power amps that I have not experienced before. After about 30 seconds I get a series of four or five clicks about a second apart, through the Electrostatic panels. I have swapped amps around and the issue only occurs on the High Frequency electrostatic panels. If I revert to previous bi wiring to single amp the problem goes away. The clicks are not particularly loud but I am concerned that they might cause damage to the panels in the long run.

My current solution is to switch off power amps then immediately remove one of the speaker wires attached to the electrostatic panels at the speaker post. After around one minute I re-attach the wire to the speaker post.

Any ideas on a better solution

thanks

Alan
 
The question of importance is whether the click comes from a discharge between the panel and the stator, which would be very bad indeed.

First thing to do is vacuum the panels (see manual, page 22). This of course the advice everybody always gives with MLs.

My Spires make a bloop a few minutes after the signal has gone, this is the panel being discharged. The sound is not from the panel. OTOH, 30 seconds is a bit short for this, and your speaker wire disconnection trick should not have any effect. This leads me to point my finger at the amplifier's discharging, and when only the panel is attached to that discharging amplifier, causing it to click. However, if an amplifier were faulty, your switching them around would have shifted the problem, yet it didn't.

Perhaps a mail to Crimson?
 
Thanks for your thoughts, Mark

I have contacted Crimson and received an extremely detailed reply that has helped put my mind at ease.


Here is the reply I received, which Peter has kindly given me permission to post. I hope this may help others in a similar situation :-

Dear Alan,

Thank you for your email and congratulations on your new purchase. The symptom that you describe is not a fault and will not cause damage. The sound that you are hearing is the reservoir capacitors discharging. The speakers you have are hybrids (electrostatic panels and dynamic bass cabinets combined). When using a single pair of 630s, the single pair of 630s are seeing the whole loudspeaker. Consequently, the discharging caps (when the amp is switched off) will be seen by both parts of the loudspeaker. The click/pops will be spread across both types of driver (panel and cone) and will discharge more quickly and be less noticeable, as a result. In bi-amping you have a dedicated amp channel to each part of your loudspeaker. It will take longer for the caps to discharge and the loading on them will be different, as there is no connection between your drivers. Consequently there is more energy for each driver type to disperse. Your panels, handling mid and high tones, will make this higher energy dispersal more obvious due to the higher frequencies that they operate at.

It isn’t anything to worry about. However, if you wish to discharge your caps more quickly and with less noise, you should leave music playing (be it from a tuner, tape, CD, record, or computer file) and then switch your power amps off using the switch on the front of each of the power amps. I would turn off the amps driving the panels first, followed by the amps driving the bass drivers. This should dramatically speed up the discharge process and minimise any sounds heard when they do so.

I hope that the above is of both interest and assistance. Enjoy your music, keep safe and stay healthy.

Yours sincerely,

Peter.

Peter J. S. More A.A.E., M.I.M.I.
Managing Director.
Crimson Products Ltd.

P.S. I would advise you never to pull out the speaker wires until the amps have been off for several minutes and there is no sign of any illumination of the heatsink mounted LED, however faint. There is significant electrical energy (circa + and - 53VDC) stored in the reservoir capacitors and voltage rails at switch off. It would be very easy for you to either electrocute yourself, or to accidentally touch the positive and negative speaker plugs together, shorting out the amplifier output stages and, apart from the damage to your amplifiers, there is the potential for your speaker plugs to weld themselves together!
 
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Thanks for the detailed and precise confirmation of my suggestion "This leads me to point my finger at the amplifier's discharging, and when only the panel is attached to that discharging amplifier, causing it to click."

You definitely have a nice system, I don't see the Ascent i's i the pictures of your cinema room, so I guess you have a separate stereo system with the ESLs.
 
You definitely have a nice system, I don't see the Ascent i's i the pictures of your cinema room, so I guess you have a separate stereo system with the ESLs.

I am fortunate enough to have a separate system for stereo. My footer links are a bit out of date as things have moved on quite a bit since originally creating the Cinema room.

The Stereo system is in our Living Room and consists of:-

Sources

Rega Planar 2 turntable, Marantz NA6006 network streamer, NAD C542 CD Player, Squeezebox Touch

Amplification

Audiolab 8000Q Pre, 4 x Crimson 630C Monoblock Power

Speakers

2 x Martin Logan Ascent i

I must admit the Logans are a bit special. They create an amazing three dimensional sound stage that can take your breath away when fed a high quality source. I don't get the chance to listen to 2 channel that often, but when I do the Logans always bring a smile to my face.
 

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