"Arny Krueger"
Andre Jute wrote:
The indispensible Phil Allison tells us:

*******
The Quad ESL57 input transformer has an overall turns ratio of 292:1.

The bias voltage on the bass panels is 6.2kV and they require 18 kV
volts p-p of audio to reach full output.

The bias voltage on the mid/high panel is 1.5 kV and requires 6 kV p-p
of audio to reach full output.

The Quad ESL63 has a bias voltage of 5.2 kV on the panels and requires
16 kV p-p of audio to reach full output.

I doubt that Phil ever told such a whopper.
The audio voltage never exceeds the diaphragm voltage.

Exception:

http://sound.westhost.com/project105.htm

polarization is speced at 1.5 KV, and maximum drive is 2.5 KV RMS


** Actually, the page says 3kV rms max. This is due soley to the cheap
transformer used - apparaently it's a 100 volt line tranny for PA systems.


The turns ratio of ESL speakers is usually in the 80-100:1 range. The
maximum RMS input of the ESL-63 is given by some as 10 volts RMS. This
would lead to no more than about 1 KV.


** More complete ******** from Arny.

Here are the FACTS:

The "Instruction Book" says the ESL63 is designed to work with amplifiers
of 100 watts per channel at 8 ohms - eg the Quad 405 ( I have a copy in
front of me). Such an amp can deliver 28.3 volts rms or 40 volts peak
(undistorted) to the speaker.

The published specs for "Maximum Input" a

" Continuous input ( sine wave) voltage 10 V rms

Programme peak for undistorted output 40 V

Permitted peak input 55 V "


The ESL 63 has TWO input transformers with primaries in parallel and
secondaries in series with the centre connected to speaker ground. Each
transformer has a turns ratio of 94:1 - ie when driven with 1 volt rms
the output is 94 volts rms.

This makes the overall ratio 188 : 1 - see schematic:

http://www.quadesl.com/schematics/quad63_schematic.gif


Now, 28.3 times 188 = 5,320 volts rms

(= the max drive voltage to all sections of the speaker)

5320 volts rms = 15 kV p-p.

QED.




........ Phil