I think Paul put a sticker under the grills of some of the ones he converted to the single-driver model, although I had one pair that was the SD version that didn't have the sticker.
I can tell you that the SD version sounds markedly rolled off in the treble compared to other speakers. It may play "close to flat" on top if "close" is defined as -3dB at 15kHz and around -6dB at 20kHz...
I can tell you that the SD version sounds markedly rolled off in the treble compared to other speakers. It may play "close to flat" on top if "close" is defined as -3dB at 15kHz and around -6dB at 20kHz...