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In Reply to: upgrading amp for magnepan 3.6qr posted by howardarbutus@yahoo.com on December 12, 2006 at 07:27:04:
These will sound better than any amp I can think of, and have 50 milli-ohms output impedance. Their ability to control my MG-20s was an education for me. The folks who have heard them all say they sound warm like tubes but more accurate and detailed.
Follow Ups:
Al, do you have a business relationship with Gilmore? At one time I was under the impression that you did. Correct me if I'm mistaken.Thanks,
After the CES show a couple of years ago, I realized my room was too small to show the Gilmore speakers to their advantage and terminated the relationship. There would have been no point in trying to demonstrate the speakers when I could not provide a listening position sufficiently far back to allow the ribbon and woofers to blend.I'm simply Mark's friend and reporting what I've found to be true with these amps. They really are that good with low-impedance loads like Magnepans, where tube amps of reasonable size and power dissipation cannot exert sufficient control. I thought the InnerSound amp was a good match for the Magnepan bass panels, but even that size of linear amp does not fully control the speakers.
I don't know how well users with high-impedance speakers optimized for SET amps would like the Raptors: most of the damping is built in to the speakers by design and increased damping in the amp adds little. These amps have little distortion, and some folks I know seem to like the sweetening of SET second harmonics.
Thanks for bringing me up to date. Yup there's definitely room for a reasonably-priced amp that can drive the heck out of a pair of big Maggies.Regarding speakers designed for low damping factor amps, in most cases probably best to stay with the type of amplification they were designed for. A low damping factor amp will increase its power output into the bass impedance peaks, and this can be used to extend the bass deeper than it would normally go with a high damping factor amp. I use this "cheat" myself.
Every amplifier has a damping factor related to its output impedance, and every dynamic speaker depends on the connected amplifier for its damping. You are right that connecting a speaker that needs higher output impedance in the amplifier to achieve optimum damping (low damping factor) to an amplifier with low output impedance (high damping factor) results in diminished bass power. This is a case of overdamping. The Raptors would not be optimum for speakers designed specifically for amps with high output impedance, as they would overdamp the drivers.The other side of the coin, where a speaker that depends on low output impedance in the amp (high damping factor) is connected to an amp with high output impedance (low damping factor), is called underdamping and results in boomy, uncontrolled bass.
I don't think it is cheating to use an amplifier that provides the damping factor that is close to optimum for a particular speaker. Unfortunately, with multi-way speakers, the damping situation is more complicated. Maggies seem to have inter-driver and out-of-band resonances that need very high damping factors in the amps (over the audio frequency range) to control them. Well-designed box speakers have enough mechanical isolation between the drivers to make this less of a problem. They may still need a high damping factor for each driver, however, depending on the design.
I posted with permissions a re-write of an article on this topic from 1954-5, when all amps were tube and all good speakers needed lower damping factors. See the link. It was written for the intelligent hobbyist, and is still a good reference.
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