Posted by Marcos Augusto on September 15, 2002 at 00:56:09:
In Reply to: Re: M-1 Sensitivity posted by Lew on September 13, 2002 at 12:54:34:
if i remember correctly, one of the "at-home measurements" i did when i first got my A-1's was the "speaker sensitivity per watt in decibels", so, after setting up a calibrated microphone about 3 feet away from the front of one of the speakers (midway from top and sides), and applying a pink-noise signal while adjusting the power supplied to the speaker to show approximately 1 watt on my power meter (an "Audio Technology 510" peak power meter, reviewed both by "Audio Magazine" and "High-Fidelity" years ago and found to be very,very accurate and which is fully adjusted to work in conjunction with the SoundLab A-1's !), i got a reading on my "Gold Line" 1/3 octave digital RTA of about 76 decibels....
granted that these weren't the most scientifically correct means of measuring speaker sensitivity, but that figure seemed to agree with the experience i've had so far with my A-1's, which seems to just "eat
-up" power amplification to play at levels above 90 decibels.
as we all know, for every 3 decibels increase in apparent loudness to the human ear, the power amplification needs to be doubled, so, if each of my A-1's produce 76 decibels with a 1 watt input, to produce 88 decibels it would need 16 watts of input amplification...
of course i am aware of the adage that electrostatic speakers "see" voltage as opposed to "watts" but i am also aware of the review of the A-1's by Dick Olsher, in which he stated that from about 100 hertz to 2.000 hertz the speakers showed an average impedance of 6 ohms, slowly declining to 2 ohms at 10 khertz.
so it would appear that a large portion of the frequency-response of the A-1's, where most of the crucial musical information is located, shows an average impedance of 6 ohms... in my particular case, i have my A-1's crossed-over at 80 hertz to a pair of subwoofers, making it even easier for me to adjust my peak power meter to an average impedance of 6 ohms.
....and while we are on the subject of the "famous" Dick Olsher review of the A-1's, when will SLOG have it available here ??? i used to have it bookmarked on my computer but the link to it doesn't exist anymore and so i lost it and can't find it anywhere else....
and i am talking about the full, complete review that discusses the different impedances of the A-1's depending on which frequency they are measured, a review that not even the SOUNDLAB website has posted in its entirety, which i don't understand why !!!
does anyone here know of a link to the complete review of the A-1's by Dick Olsher ??? i would appreciate that very much, thanks...