ESL bias voltage and sound output data

[bentoronto]

Data point:

I've been developinng panels comprised of 6 Dayton-Wright XG8 cells, originally built around 1975 (and used with a Sanders-like high voltage direct drive amp).

Last week, went from 5.8kV bias to 8.8. Surprising since we've had very muggy weather recently. Gained a very substantial amount, roughly 16 dB.

Mostly charged over night. But took almost 2 days for last dB or two. I am told that diaphragm coatings become more resistive with age and there's no downside to high resistance aexcept maybe time to charge.

Speakers really lit up with the higher voltage, sound-wise at least (so far). Good to have lots of headroom in an amp, I suppose. Playing loud at my chair, I measure up to about 90dBC on my old Radio Shack meter and Mahler's Second Sym really thunders*. No pity for you staid Quad owners!

Ben
*it's one of my CDs with the most sub-30 Hz sound**... they bang the side drum through a lot of the last movement, not to mention the organ pedals on the Solti recording.
** neat-o to have a DSP channel driving a sub-sub-woofer only below 30 Hz. A great way to eyeball if there's any content down there.

 

[geraldfryjr]

Very Good!!!

I was running that much bias on my Desktop ESl's!!!

They played with much authority and because of the increased efficiency it took only a 5Vpeak signal in to 1:160 to reach +90db, that is pretty darn good considering the small surface area.

With a 40Vpeak (average 100watt amplifier swing) signal I was getting +105db!
At 1 meter Screamin' loud and clean!!

FWIW

jer

 

[tyu]

Jer......how right you are.. bias bias bias......for years now you an I have post here about how much better most ESLs sound with the bias move up...an setup so the owner can set the bias....but it like....most don't care...an if thay do come around to higher bias.....an getting more output an better sound.....it like Wow it new!.....hehe

jer..... thanks for all the years of your input on ..getting better sound with ESLs...
As much as I like my Acoustats....I would have had to move away from them if I had not got the bias up...an dropet that 500mg ohm...bias feeder res.... 60-30 meg is as high as I well ever go .....the sound diff is night an day......to me an others...

 

[bolserst]

…Last week, went from 5.8kV bias to 8.8. Surprising since we've had very muggy weather recently. Gained a very substantial amount, roughly 16 dB.

Hmmmm….likely more is going on here than simple bias voltage increase as you should have only increased the diaphragm charge by just a bit over 50% resulting in 3dB increase in output. I wonder if the higher voltage and higher humidity has helped charge the cells better, similar to the sudden increase in output you get when you exhale moist air onto a failing diaphragm coating or contact. Your comment about the coatings getting more resistive with age seems to support the thought that the higher humidity is helping compensate for the loss in conductivity.

Do you happen to have a blinking neon light charge indicator in your setup to determine how much leakage you have in the bias circuit?

 

[bentoronto]

Hmmmm….likely more is going on here than simple bias voltage increase as you should have only increased the diaphragm charge by just a bit over 50% resulting in 3dB increase in output. I wonder if the higher voltage and higher humidity has helped charge the cells better, similar to the sudden increase in output you get when you exhale moist air onto a failing diaphragm coating or contact. Your comment about the coatings getting more resistive with age seems to support the thought that the higher humidity is helping compensate for the loss in conductivity.

Do you happen to have a blinking neon light charge indicator in your setup to determine how much leakage you have in the bias circuit?

Could be that the speakers hadn't reached their baseline at 5.8kV before I increased to 8.8 kV. Or other slips in measurement.

But the subjective memory of running fully charged at 5.8kV and then 8.8kV (albeit stretched over a few days) is closer to maybe 10+ dB than 3dB on a Mahler symphony. Definite large enjoyment boost that wouldn't be true of 3 dB.

Don't you square the increase? 50% is 2.25 times, just under 10 dB.

Sorry, I don't know the neon circuit. Glad to learn, please.

(Due to house painting, no HiFi running just now.)

Ben

 

[bolserst]

Don't you square the increase? 50% is 2.25 times, just under 10 dB.

Force increases linearly with bias voltage, so doubling bias voltage should give 6dB SPL increase.
http://www.diyaudio.com/forums/plan...m-resonance-change-hv-bias-2.html#post2378013

Sorry, I don't know the neon circuit. Glad to learn, please

Some links to discussion and pics of the neon circuit.
http://www.diyaudio.com/forums/planars-exotics/76222-esl-build-thread-12.html#post952272
http://www.diyaudio.com/forums/planars-exotics/153773-esl-technical-questions.html#post1958015
http://www.diyaudio.com/forums/plan...ogan-sequel-ii-dead-panels-7.html#post3731257

 

[bentoronto]

Force increases linearly with bias voltage, so doubling bias voltage should give 6dB SPL increase.
Some links to discussion and pics of the neon circuit.

OK, linear, not square. But the hedonic benefits in loudness were certainly more than 3dB.

Thanks. I'll wire in a neon indicator for each panel.
Ben

 

[bolserst]

OK, linear, not square. But the hedonic benefits in loudness were certainly more than 3dB.

Oh, I wasn't doubting your SPL increase.
I was just suggesting that it must be due to something in addition to the 50% bias increase.

 

[bentoronto]

With your excellent courtesies, you must be partly Canadian in origin.

I'm sorry to (again) post "imprecise" data. Not hard to re-do tests except that it takes a day to asymptote and the mic and volume control have to be held in place with duct tape the whole time.

Ben