Relative air humidity on electrostat performance

Hello good people -

I sincerely doubt that I am the only person who has experienced this personality trait of electrostat speakers, that is, as the relative air humidity of the listening room increases/decreases through natural atmospheric changes the sound coming out of the speakers changes as well. In particular, as the humidity increases the sound becomes muddy, distant and diffuse - and takes more gain to reproduce a constant listenable level - and as it (the humidity) decreases the bass becomes much less noticable and the mids and highs are articulated to very high, and sometimes piercing, levels.

Now, I am a rather level-headed fellow and I do not let the above mentioned topic cause me to lose sleep. But what, if anything, outside of running a noisy dehumidifier either during or just before listening sessions can aid me in this dilemma? I mean, Lucinda Williams or Diana Krall deserve to be reproduced at the levels they are accorded to on a fairly consistant basis.

My system:
Krell 300 KAV
Blue Circle BC3(Despina) w/XLR inputs/outputs
Bryston 4BST
Transparent Audio Balanced Musiclink Plus (all around)

Thanks ahead of time,


Call Roger Sanders at Innersound. He is the absolute "authority" on this subject and I am sure would be happy to help. Good luck.

Maybe you should consult Martin-Logan since they designed the thing, if you really think its a problem.
Gpsguy -

Your observations are absolutely correct.

At least one practical solution is a variable bias voltage power supply. That's a feature of Sound Lab electrostats, and down here in New Orleans it comes in handy.

In high humidity conditions, full performance is easily restored by cranking the bias up a bit. If the humidity drops, then just crank the bias down a bit.

There's a pair of Sound Lab Dynastats for sale here on Audiogon right now, for a grand. They are quite competitive with the SL-3's. I'd be glad to tell you more about 'em if you'd like.

I don't know if it's feasible to retrofit a variable-bias power supply to the SL-3's. The only other solution I can think of is to go with the dehumidifier.
FWIW, I don't think Krell or Bryston is a good match for Martin Logans as they both lean toward the "bright" side. You might want to get some tube stuff.
I have my ML monoliths with a biased power supply to adjust the kV on the panels. It works very well. I initially did it because the older monoliths ran at a higher kV than needed--it just shortened the life and made them a bit on the bright side--particuarly once I got rid of the old grill cloth--something the newer ones do not have (and shouldn't). As a result, though, I learned I could actually tune the speakers to compensate for the humidity changes. There is no question--that ESLs are humidity sensitive. Now all you need is one that has a humidistat coupled to a potentiometer and calibrate it for best results in your environment (hmmm).