Doping means applying any kind of liquid to the speaker cones to change their performance characteristics, not using airplane dope. Airplane dope is nitrocellulose dissolved in ether or other highly volatile solvent. It isn't stiff and the solvent would be hell on surrounds. Stay out of the hobby shop. Damar varnish is fir tree resin dissolved in turpentine. Very, very different from airplane dope, which was formerly used to coat fabric-covered wings and tail surfaces and, more recently, to coat fine silk for model airplanes. Dope-and-silk has been almost entirely replaced with heat-shrinkable plastic.
Will
Will