2. speakers
  3. 1106606958

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
eldartford OP
4,262 posts
 
Aroc...You could probably compensate for playing your Maggies at lower SPL by using one of the excellent and inexpensive analyser/equalizers that have appeared on the market. Check out the Behringer DSP8024, less than $250 including mic and cable. Behringer also has a slightly more expensive model that some audiophiles like, but it has many other features that you don't need. (www.zzounds.com is one of many sources for Behringer).

If price is no object, get a PARC.

By the way, Maggie crossover parts, at least in the MG1.6 that I upgraded, are far from junk. Replace the iron core inductor, but replacing the Solen caps may be overkill.

I will make some more measurements this afternoon while the wife is at work. It's nice to be retired :-)
loontoon
301 posts
 
No blown tweets, I also drove them better than expected with a Cary SLA 70, read 35 watts/channel.

So I like loud but I like my ears and the Cary got them past the point where they had to be. In fact they sounded very good. Better than any 35 watt amp has a right to make maggies sound.

1st turn it down. At 85+db your into the ear damage range if you listen very long. That's average level, peaks will go to ?????

I am negotiating a 300W pair of mono toobs so, if I buy them I will report a gain in a couple of weeks.

loon
eldartford OP
4,262 posts
 
Loontoon...Of course 96 dB is too loud. Only a few of my recordings (Wurlitzer theater organ concert for example) would reach this level. Remember I was doing an experiment.

Long ago when I had MG II speakers I drove tham with a 2 X 35 watt Eico tube amp, and I thought they sounded good. As the saying goes "Been there, Done that". I am sure that the 300 watt upgrade will impress you.
aroc
760 posts
 
I have the 2.5Rs now. They have that midrange dip at c. 1khz. I should measure then with test tones at 70dB SPL referenced to 1khz or lower(rather than 80dB SPLat 1khz)and see if the midrange flattens out. (a la fletcher/munson) With the midrange dip, my speakers might work out to have a built-in "loudness" button, LOL.

Aaron
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.
More to discover