Apogee vs Soundlab

Ralph, what would happen if I'm using a 10 ohms resistor in the treble section of the Soundlab (instead of using the "brilliance" control rheostat)? Would that prevent for the solid state power amplifier to "double" power? Whay don't I hear the same treble characteristics with the Quad ESL 63?

Chris

Chris,
this is purely personal experience and hence highly subjective:
I've owned Quads for decades and was never really satisfied with their high end. In the olden days I put Sequerra ribbons on top of the 63s to get the highs I liked and later the aCapella plasmas. I still have those, but feel no need to use them with my Sound Labs where I have the control rheostat at full tilt boogie.
Curious to hear what Ralph will say to your idea.
Wondering if your trouble couldn't also possibly be room dependent and if I, because of my age, should stop talking about the high end response of speakers, because my ears won't hear it no more anyway.......

Chris- check out what Jafox used in a mod on his speakers:
"I also replaced that horrible "brilliance" rheostat with a gold plated double-contact selector switch of 6 resistance values (values 0-> 2 ohms range). Treble clarity significantly improved. And with an occasional treble-hot recording, being able to attenuate the treble a little bit is mighty nice. It was amazing how much treble grain existed with the original rheostat."Maybe this will help out your situation.

Jafox, what make of selector switch did you use on your SL?

Dazzdax, one thing you might try is to put a resistance in series with the speaker. Two to four ohms ought to do (some audition might be a good idea), but it should handle high power. This will simulate an amplifier with a higher output impedance and will substantially reduce the power doubling problem. A fair amount of power made by the amp will be absorbed by the resistor, so this is not a very efficient means!

The impedance curve of the Quads is bit different from the Sound Labs, if I recall right the Quad matching transformer operates full range (the Sound Lab is a full-range diaphram driven by two transformers which are crossed-over to operate two frequency bands). I doubt that it has the same bandwidth as a result.