What does more power do for Magnepans?

You might want to read a thread I initiated on this subject, starting as follows...

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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?
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Of course there was a lot of follow-on discussion that may be of interest.

Eldartford, 96db peaks is LOUD to me, certainly not a volume I'd listen to for more than one song at best.

Also, I assumed that Maggies need power and used the Parasound JC1's for most of the 3 years I owned them. After committing to buy a more efficient 8ohm speaker, I bought Atma-Sphere MA1 MkII.3 OTL amps. I received the amps before I sold the MG3.6r's so decided to see how they sound.

The Atma-Sphere amps drove the maggies SO incredibly well that I seriously questioned if selling them was the right thing. They were incredibly transparent, RELAXED (no strain evident), tonally beautiful, the bass was so much more REAL and subjectively went deeper, and detailed as can be...that ribbon tweeter can be glorious with the right amplifiers. I didn't listen at louder than 90db peaks for the most part during the 3 weeks I had them setup with the Maggies, but that is as loud as I ever listened with the JC1's and the JC1's sounded seriously strained in comparison.

In short, if I were using Magnepans today, there is no way I would use anything but an Atma-Sphere amp. I would have laughed at someone saying that before I tried it myself.

Which brings up an important question. At what point do the Magnepan panels start to break up and "compress", requiring significantly higher ratio of power for each db increase? Your measurements suggest 96db may be in that region?

Jordan

Germanboxers...As you say, 96 dB is too loud for listening. I was running a test.

Being a retired engineer, I have made a bunch of measurements, including looking for compression. I saw no compression up to a SPL where I would fear for the safety of the speaker. The only time I have had maggies "bottom out" was with non-musical LF thumps, such as might occur due to a wiring defect. Using a subwoofer to get the high excursion LF signal out of the maggie helps a lot.

I would very much like to try a big Atma-Sphere amp, but my lottery tickets always have the wrong number on them.

Eldartford,

Thanks and I do remember your thread now that you brought it up. I've read so many maggie threads it becomes a blurr. I am slowly learning how to figure this stuff out myself. (Mostly by putting my foot in my mouth).

Quick question if you have time. How do you measure voltage across speaker terminals? Voltmeter in series with either pos. or neg. side? Can you do this with a cheap RS multi-meter and get an "accurate" measurement?

Jim S.

Stilljd...Even a "cheap" multimeter is plenty accurate enough. (An oscilloscope. if you had one would be the best because you could see the peak voltage directly). My RS meter is digital, and displays a new measurement about once per second. As the music volume varies you monitor the reading and take the highest one as the short term (1 second) rms value.From the rms value you can estimate what the peak would be. The meter is connected directly across the speaker terminals, at the amp or at the speakers. Not in series. That would be for a current measurement, but don't try that with a voltmeter.

You will be happy to see how little power is applied most of the time at moderate volume, but the increase during loud passages played loudly is surprising.