Sound Lab full-range electrostats aren't spec'd to 20 Hz, but I have customers who have measured their M-1's, A-1's, and U-1's as having substantial output in that region.
A few months ago I delivered a pair of A-1's to a customer's house, and he wanted to measure the bass extension. So we used a Stereophile test disc of 1/3 octave warble tones, and a Radio Shack sound pressure level meter. The bass held up quite well, measuring only 6 dB down at 20 Hz. But, that's not flat to 20 Hz, now is it?
Well, maybe it is. The Radio Shack sound pressure level meter is down 6.2 dB at 20 Hz! So according to this crude measurement, these A-1's were truly "flat" (relative to the 1 kHz level) down to 20 Hz, with the -3 dB point somewhere lower still! Not bad for a full-range electrostat. The metal-frame U-1 will go even deeper.
I'm not suggesting Sound Labs for people who place a high priority on shaking the room with ultradeep bass, just noting that in the real world they can go down suprisingly deep. Even though I'd heard reports of similar results from customers, I was skeptical until I actually participated in the measurement process.
Duke
A few months ago I delivered a pair of A-1's to a customer's house, and he wanted to measure the bass extension. So we used a Stereophile test disc of 1/3 octave warble tones, and a Radio Shack sound pressure level meter. The bass held up quite well, measuring only 6 dB down at 20 Hz. But, that's not flat to 20 Hz, now is it?
Well, maybe it is. The Radio Shack sound pressure level meter is down 6.2 dB at 20 Hz! So according to this crude measurement, these A-1's were truly "flat" (relative to the 1 kHz level) down to 20 Hz, with the -3 dB point somewhere lower still! Not bad for a full-range electrostat. The metal-frame U-1 will go even deeper.
I'm not suggesting Sound Labs for people who place a high priority on shaking the room with ultradeep bass, just noting that in the real world they can go down suprisingly deep. Even though I'd heard reports of similar results from customers, I was skeptical until I actually participated in the measurement process.
Duke