Audiostatic ES300RS missing dBs

[brxl]

Hello all,

I have replaced the diaphragm and put new coating (Silberstatic.de) on my ES300RS panels.

Upon charging there is crackling for about 10 secs, later they are quiet, but of course there could be some during music playing.

I may have been a bit generous on the coating (doing 3 layers), so I took one panel apart again and washed/thinned the coating with rubbing alcohol, visually it looks less now, no measurement of Resistance or layer size though.

The crackling sounds appear to have been a bit shorter now on this panel, but before proceeding on removing more I would appreciate your input....

😕

because they play with fantastic details,



I like them more than my Quad 63s right now

Now hat may also be due to the fact they have new diaphragms, who am I to know how the 63s could sound if rebuild?...but also the sensitivity between them is like day and night. I only recently bought the 63s, so I don't have a before or after effect with the Audiostatics to compare to...it is just so noticeable.

The 63 should come in at 86dB/1W the Audiostatic at 88dB/1W...the Audiostatics are however noticeably lower in SPL. Without measuring I would say "only half as loud" that is 10dB...What could be the reason for this low sensitivity?

Cheers
Brxl

 

[AcoustatAnswerMan]

Have you checked the high voltage bias? I don't know what it should be on your speaker, but a loss of efficiency is often caused by a drop in the bias voltage. Be aware that a high voltage probe is usually required to measure high voltages, especially in a high impedance circuit like an ESL bias supply.

 

[brxl]

Have you checked the high voltage bias? I don't know what it should be on your speaker, but a loss of efficiency is often caused by a drop in the bias voltage. Be aware that a high voltage probe is usually required to measure high voltages, especially in a high impedance circuit like an ESL bias supply.

Thanks for the idea...it should be around 5kV...do not have a high voltage probe (yet), it is derived by a Cockcroft-Walton-cascade with 19 condensors and diodes.
Should I be able to read 5000/19= 263V over each diode then?

Cheers
brxl

 

[AcoustatAnswerMan]

Thanks for the idea...it should be around 5kV...do not have a high voltage probe (yet), it is derived by a Cockcroft-Walton-cascade with 19 condensors and diodes.
Should I be able to read 5000/19= 263V over each diode then?

Cheers
brxl

Somewhere in that range, yes. You may find, however, a steadily decreasing voltage increment at each stage due to loading effects of your meter. I've never been fond of measuring high voltage multipliers that way - very easy to get your meter probes in the wrong place and...poof goes the meter. Better to use a proper HV probe at the output of the multiplier. But even with a high-impedance HV probe, you will likely measure less than the actual voltage due to loading effects of the probe.

 

[brxl]

I may sound like a cheapskate here, do not have an Osci but a ton of cheap DMM's (some of harborfreight's free items with your purchase origin)

Thinking of measuring across one diode by connecting first, setting the DMM and then plugging in. Observing from a distance and if the DMM goes, not a great loss, I can unplug the HV supply from the sidelines. Just need inflammatory underlay 😉

 

[bolserst]

…The 63 should come in at 86dB/1W the Audiostatic at 88dB/1W...the Audiostatics are however noticeably lower in SPL. Without measuring I would say "only half as loud" that is 10dB...What could be the reason for this low sensitivity?

Sensitivity ratings based on power rather than voltage often cause confusion since a volume setting on your amplifier specifies a certain voltage output not power.

In the Quad brochures, the sensitivity is specified as 86dB/2.83Vrms @1m.
The Audiostatics that I have measured all were in the range of 77dB – 80dB/2.83Vrms @1m.
Diyaudio member Capaciti had similar results: HELP needed with Audiostatic ES200RS low SPL even after new foil

Stererophile put the ES-100 at about 80dB/2.83Vrms: Audiostatic ES-100 loudspeaker Measurements | Stereophile.com
“Footnote 1: Despite this low voltage sensitivity, the Audiostatic is actually quite efficient in the midrange and below, due to its very high impedance. Driven with 2.83V, which will result in 1W power dissipation in an 8 ohm resistor, the ES-100 actually draws much less than 1W from the amplifier to achieve its 80dB spl”

The information above may completely explain the sensitivity differences you are experiencing. If not, consider that a 20 stage voltage multiplier will easily have its output voltage pulled down even by very small leakage currents. When performing the measurements you have been discussing with AcoustatAnswerMan, you might consider doing the measurements once with the panel hooked up, and once with it disconnected to see if leakage currents from the rebuilt panel are pulling the voltage down from 5kV resulting in additional sensitivity loss.

 

[brxl]

I am overwhelmed by the quick and helpful answers, thanks a lot.

The sensitivity measurements do indeed explain much better, and yes before the new diaphragm they were hungry for power if asked to play at pretty normal levels 🙂

I will measure with and without panels, I'll probably get around this earliest this weekend,
cheers
brxl

 

[AcoustatAnswerMan]

Bolserst - perhaps you can confirm - shouldn't the voltage at each stage of the multiplier be measured across each capacitor, rather than across each diode? I've always had an HV probe at my disposal (ever since birth, ha ha) so I've not much experience measuring stage voltages.

 

[bolserst]

My preference is to measure across the capacitors, but you can measure either way. The advantage of measuring across the diodes is that it will be half the voltage of that across the capacitors (except the first cap). The downside is that it is more work to calculate the total output voltage.
See example figure taken from: there's a way to understand the limit of hv bias?

A post on minimizing loading when measuring multiplier here:
Acoustat Answer Man is here: Post#1513

 

[MJ Dijkstra]

I got a HV probe and as I remember the audiostatic has around 5,2 kV. Measure the output!
I wonder why putting 3 layers of coating.....

 

[brxl]

An externally hosted image should be here but it was not working when we last tested it.

I am not able to measure across the diodes, this is to close.
Instead I went capacitor by capacitor, the outer row added together gets 2kV, since there is an inner run of similar caps on the side towards the transformers...I'll make a wild assumption in just doubling the output so that gets to 4kV...and it does not change noticeably between free running or panel connected.

So I was also informed that I can tighten the diaphragm by using a heat gun/hair dryer...as long as I stay below 140C. Measured the output of the hair dryer at 80C and did one run...the crackling completely disappeared...well off to the other panel...careful et voila...no crackling either. So I must admit there was too little mechanical tension. Sensitivity is better as well, need some time to listen before comparing with the other ESLs.

Thanks for your input.
brxl