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Wayne Picquet in Florida, U.S.A. has been rebuilding original Quad ESL panels since about 2002. From pretty humble beginnings, like all the rest of us, Wayne has gone on to produce what I, and a number of other Quad fanatics, consider to be the best sounding Treble Panels available for your original Quad ESL.
Big statement? Yes, but I stand by it, and by what it represents. It is not the purpose of this site to advertise any one individual's product - please look around - you will see that Quad, Germany, U.K., and many other manufacturers, parts suppliers and so on are represented here. If they are not, please let me know, as I am always interested in promoting useful parts and suppliers for the enthusiast to rebuild their speakers, either from scratch or by replacing panels.
Yes. Wayne's Treble Panels are the only ones I know of in the world right at this moment that actually meet the original specification 100% correctly. There are many other ways to rebuild an original Quad ESL panel and get acceptable results. They all use non-original coatings, or non-original something-or-other. They usually produce a nice sound, but not the sound of a factory fresh panel.
Partly a commercial secret, but basically, attention to details and perseverance. The panels are made using 6-micron material, not 12. They are stretched on a jig which is a duplicate of the original Quad jig, and then appropriately heat-treated. They are coated with soluble nylon, which is the correct, original coating. A thousand other small things which all add up to give you the best panel possible. As I say, a duplicate of the factory originals in all respects.
The PK Treble Panel
Here is brief note on a panel I have recently had here for review which I believe is the closest that you will here to the original Quad panels as produced at the factory circa 1960 through 1980. It is that good!!!
I believe this to be the only 6-micron panel replacement that you can get out there that precisely matches the original Quad to a tee at this time. It is tensioned properly in an exact replica of the original Quad jig, and has soluble nylon coating on the panel diaphragm. The panel diaphragm is 6 microns which is correct for a Quad treble panel and not the 12 micron “heavies” being peddled out there today. Get one of these - I don't make that recommendation much - they're worth 3 times the price!
The panel presents as a standard, original Quad Treble panel, minus rivets. A more secure fixing method using 2.5 mm stainless steel metal threads has been employed. The panel is freshly spray painted a very pale gray colour and wired with very flexible high voltage wire (~3 to 5 kV). Sufficient length of this wire has been provided for standard termination in the speaker as required. Felt damping pads have been used as per the original standard and secured with nylon bolts, washers and nuts. This should reduce leakage on the panel somewhat. Dust cover finish is of a very high standard, and the panel is well sealed with conformable polythene tape to prevent dust entry even at the wiring exit points. The panel is very marginally heavier than the stock, standard Quad panel, due, no doubt to the heavier duty fasteners used.
The panel exhibits no electrical malfunctions or misbehaviour of any kind. The capacitance and resistance (reactance) of the panel is correct, and essentially duplicates the original Quad specification per patent. The panel does not hum, with or without signal applied. Surface resistivity of the diaphragm coating was not measured directly, but is estimated (by bridge balancing) to be 1011 to 1012 ohms per square. This is consistent with a soluble nylon coating being applied to both sides of the diaphragm, but is not conclusive evidence of this.
Installation of the panel poses no problems for the experienced installer, taking no more than 10 minutes to fit once the speaker is disassembled. Colour coding of the connecting wires would be an advantage for the less experienced installer. The dust covers may need slight heat shrinking on installation as the panel is assembled flat and then fitted to the standard curved frame (usually). In situ, the panel is mechanically correct and exhibits no rattles, contractions, expansions or untoward movements of any kind when properly mounted.
Panel reactance as measured in a standard bridge test indicates a 1011 to 1012 ohms per square resistance on the diaphragm, as noted above.
Frequency response is ruler flat ±0.5dB to beyond the limits of human hearing. The output is 3dB down (half power point) at 21.57kHz.
Panel resonance is estimated by calculation to be comfortably out of the pass band of the panel, and this is confirmed in listening tests.
The panel was stress tested to 102dB ambient SPL at one metre on axis. No arcing or other discharge of the diaphragm was observed.
Output (total integrated pressure) is very even across the entire length of the panel. This is in contrast to non-nylon coated panels, which produce a less even charge distribution and "pockets" of higher harmonic distortion on the panel.
None such is to be found here.
The highest frequencies are both extended (as noted by measurement), and accurate. Harmonics are properly reproduced. The measurements to 21.57kHz are reflected in the smooth reproduction of the tiniest micro-dynamics of shakers, tambourines, rivet cymbals and the sound of silk shirts/blouses rubbing on the wood of expensive stringed instruments.
There is absolutely no hint of "glassiness" or emphasis of any description in the 7 kHz to 20kHz range, as can be sometimes observed in lesser electrostatic panels (even some of good pedigree, I might add). The highest frequencies of massed strings and voices are reproduced with ease. This indicates that the multi-phase information in these types of sources is not being scrambled up, and is likely indicating the panel has very good aperiodicity. One soon gives up trying to listen for faults upon first audition because the sound is natural and correct.
To use an out of fashion "audio" word, the mid-range strips of this panel produce the true "presence" of a live performer, when such is recorded by the people in the studio. When there is microphone placement error in the studio, or phase incorrectness or an edit (!) in the recording, it is immediately obvious as with any transducer of this calibre.
Perspective and balance of layers of sound in a well-recorded, true stereo recording is correct! Massed voices resolve into the distance as they should and the recorded acoustic is apparent - assuming one can be distracted from the music for sufficiently long to be this analytical - it is an effort. The Upper bass harmonics which give us our spatial focus on instruments such as 'cello, bass viol and piano are perfectly reproduced.
The human voice is also perfectly reproduced in all registers impinging on the pass band of this panel. I am quite easily able to hear Elizabeth Schwarzkopf's breathing pattern as she sings in the Giulini reading of the Verdi Requiem (for example). As it should be, in fact, from front row, centre.
In true Quad fashion, the details such as mentioned above are only reproduced when present in the recording. There are no "inventions" upon the part of the speaker panel, which is totally free of audible resonances or any other sonic solecisms, within its pass band. The panel embarrasses the lesser recordings (that we all own), but it is a comfort to know that there is no 'glossing over' of the audio truth going on here. In short, if your system is "line me up and shoot me" bad, then this quality of panel will show you its worst features. If you happen to own a "straight wire with gain" system, then this is almost perfection - nearly - since nothing is 100% perfect).
1. This is a quality panel that any Quad owner should be lucky to get and proud to own.
Where can you get one??