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Maggies...Measured Amp Power Requirements

Just how many watts does it really take to drive Maggies? Two things made me investigate this…first: on a visit to the cellar (my system’s boiler room) I noticed that the clip leds on my 600 watt CarverPro ZR1600 amps were flashing when I played the system very loud…second: I wondered if using a higher subwoofer crossover frequency would make it possible to try a tube amp for the Maggies. Some people say a good 100 – 150 watt tube amp can sound good. My Maggies are MG1.6.

With the SW crossover frequency set to 45 Hz, and the maximum measured SPL at 96 dB, I measured up to 38 vrms across the speaker terminals. This represents 361 watts, rms.

With 38 vrms measured, the peak voltage would be at least 1.5*38 which is 57 volts.
This voltage would suggest a power amp capable of 812 watts peak (briefly). So the clipping led was telling the truth.

Moving the subwoofer crossover frequency up to 100 Hz brought the maximum rms voltage down to 26 vrms. This represents 169 watts. The corresponding peak voltage would be 39 volts, and the peak power requirement would be 380 watts.

I conclude that people who use tube amps with Maggies do not play them loudly. Another factor to consider is clipping recovery characteristics of the amp. Tube amps do naturally recover better than solid state amps, so a little clipping may not be the end of the world.

I also conclude that I can forget about trying tube amps with my Maggies. Shucks. Now what will I do with all that money?
eldartford

Showing 2 responses by jvogt

jvogt
212 posts
 
I have 1.6QR's and originally used a Mark Levinson 27.5
amp (200 W/Chan @ 4 ohms). It sounded good but not
outstanding. At higher levels it sounded constricted with
a loss of dynamics. I sold the 27.5 and got an ML 335
(500 W/Chan) which greatly improved the performance of
the 1.6's.
jvogt
212 posts
 
I don't believe the improvements were strictly that the
335 amp is "better" than the 27.5, which has been regarded
as one of the most refined and musical amps ever produced
by Madrigal. I was not anxious to dispose of the 27.5
because of its musicality: tight bass, open airy midrange,
three-dimensionality. I've owned many amps over the years
and the 27.5 remains a favorite. However, it just didn't
have the "juice" to drive the Magnepans to their full
potential. The 335 is just a more powerful amp, and did
not experience the dynamic constriction evident with the
27.5 on the 1.6QR's.
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