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In Reply to: Joseph Audio and Merlin posted by BT on September 25, 2001 at 07:38:41:
but if memory serves me, they're 83db sensitivity.83?
please understand that i am w/ you. i own merlins and am obviously partial (but musically satisfied!), and i greatly respect the JJ designs.
however, 83?
(i hope memory doesn't serve me, as it would greatly limit equip matching to what is likely another great design by JJ).
btw: vsm-ms are 90db 8ohm, match great w/ a 20w tube amp.
rhyno
Follow Ups:
The RM33si works well with all but the very lowest power tube amplifiers. Sensitivity is greatly misunderstood, with the common wisdom being that the higher the number, the easier the speaker would be to drive. However, there are other factors that the amplifier may encounter such as large phase angles and low impedance. In fact, a low impedance speaker of higher sensitivity derives the higher output
by drawing more current. This tends to make small SET amps unhappy, defeating any advantage that the higher sensitivity would offer.
(apart from the marketing advantage)The RM33si has remarkable bass extension for what is a rather small enclosure. There is no external bass equalizer required that might place more demands upon the driving amplifier. And the amplifier sees a very easy 8 ohm load with well controlled reactance.
The most advanced drive units today, in our opinion, are not the most efficient ones. The amazing RM33si Magnesium midrange driver is specified at about 85 dB raw output.So, while the 83 dB spec might initially lead one to pass up the stunning performance of the RM33si, a simple listening trial with a given amplifier may well prove eye-opening. (and ear-opening)
(hopefully followed by wallet-opening!)Jeff
President, JosephAudio
http://www.josephaudio.com
Jeff,Are you using the Seas T25CF-002 or the T25-001 in your RM33si? Did you find it to be any more critical of cabinet diffraction than tweeters you use in your other models?
Regards,
Mike
Stereophile's measurements of these speakers came in even lower at 80db ... I remember several years ago they refused to recommend a speaker based on a VERY low efficiency measurement (but not as low the Joseph's). MC commented something like in this age of speaker manufacturing he could not recommend a speaker with an efficiency rating this low. He alluded that it indicated some poor design characteristic.I have never heard the Joseph speakers, just adding what I remember from a previous issue of Stereophile. The RM33si may be EXCELLENT. It was voted Best in Show at Hi-Fi 2001.
The 80 dB measurement does not match our data.JA did offer a couple of ideas as to why, and we're inclined to agree that the outside temperature may well have been a factor. (John does all of Stereophile's speaker measurements in the great big anechoic chamber known as the great outdoors!) With external temperatures in excess of 100 degrees the metal cones cannot dissipate the heat effectively and some thermal compression may have resulted.
President, JosephAudio
http://www.josephaudio.com
JA uses 2.83V at 1 meter for sensitivity measurements with B weighting, so this is not a true 1 watt @ 1 meter senstivity measurement. It would be if the speakers impedance over the weighting range was 8 ohms (1 watt = 2.83 Vrms into a 8 ohm load), but the average impedance looks higher than that to me (except for that short dip to 6 ohms at 500 to 500 Hz) which would mean that the 1 watt at 1 meter sensitivity for the speakers could well be a couple dB higher than the 80dB and account for another part of the difference between Jeff's specs and JA's measured number.
Rich Brkich
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