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?
I have not done conclusive testing as you, but I feel the same based on my experiences. Those who think they are getting "it" really have no clue what they are missing. In any case this is sure to be a controversial thread....
If you only listen at 85 db max is it still necessary to have that much power or are you saying the maggies don't open up until they are extremely loud, which requires a lot of power?
I agree with the above. I've used the same Carver 1600 on 3.6's and the clip lights also appeared on loud/dynamic passages.
My estimate on the 3.6's, based on over a dozen amps that I've tried, is that they need an amp that can deliver at least 800 watts into 4 ohms. I'll qualify that by saying my room is on the large side, so I'm cranking the volume more than most.
I'm currently using SimAudio W10's which deliver 1400 watts, and they work great with the 3.6's.
Of course there are some grey areas and the old argument may be raised that not all watts are created equal. Tube users might say that a tube watt is more powerful than a SS watt, but I'm not getting into that debate here!!!

The last thing you want with the 3.6's is an amp that clips, even a tube amp. I blew plenty of tweeter fuses with my Cary V12 Monoblocks - rated at 200 watts/channel.

Yeah, I don't think I got non-clipping with my 3.6s until I got the innersound ESL-300 which does 600WPC @ 4 ohms. Sounded clean and unrestrained. Also didn't blow the ribbons anymore.
Dolfan...The SPL of 96dB (plus or minus as the music varied) was very loud. Louder than I would normally listen. Remember I was curious about why those clipping leds were flashing. I will do it again at lower (reasonable) SPL. I am sure there is some point where a 100 watt amp would do. However, I have several lower power amps that I have used with the Maggies, 100, 200, 350, 450 watts into 4 ohms. All except the 100 watt would be "acceptable" at low SPL, but every increase in power up to the 600 watt zr1600 makes an improvement.

We all know that Maggies "like" big amps. But that's a little vague, so I am trying to come up with some hard fact numbers.
Controversial indeed. Ah nuts, why didn't I think to do the same experiment with my pair of JL-3 Sigs which have been driving a pair of Maggie 3.5s until tonight when a pair of Soundlab A1s arrived. With the 3.5s sidelined I just have no desire to try the Maggie measurments but maybe when I feel bored I'll give it a shot. All I can say is that the JL-3's drive the Maggies like no amp I every experienced and oh my, so very LOUD. But I did lose a tweeter last week as I did not get to the volume control fast enough on an explosion in the Roger Waters "Amused to Death" LP. So a trip to Magnepan last week took care of that. I would love to hear a shootout of the JL-3's with the massive Pass or other megawatt SS amps.
Dolfan, I would think your statement(s) might be right. I listen to my maggies between 62-78dB SPL. And maggies DO SUBTRACT low level detail at modest sound pressure levels. (less than 80dBSPL, or is it more like 85dB SPL?) In another thread Tim (tireguy) reports that he listens at about 87. He had mentioned a suggested value of 700W of tube. Give the 9 dB difference (assuming similar listening room size and listening difference [I can only guess that his room is likely bigger than mine], and assuming maggie SPL output is linear with respect to power input [i.e., no thermal compression, etc], then P=2^(dB/3), P=2^(9/3), P=8:1. So one might expect that I would need 8 times less power that he cites. 700/8=90wpc to one sig fig. Which is that power amp I'm using (90wpc with kt88 tubes, a little more than 100wpc or so with my kt90 tubes). So the SPL differences might explain why I am satisfied. Though it's likely psychoacoustical, since I don't like the sound of sand amps in my budget range, and this was the biggest tube amp I could afford at the time.

Although, I do agree that maggies sound best (at least my stock ones, with the poor quality passive parts) at >80dB SPL. But the music sounds louder than life and not as natural (to me) at those levels. It sound great at those levels, just not natural. But I do hear I'm missing some detail and magic at the lower levels! Some day I will be able to budget those mods. I probably need to address the room more as well.

Great thread eldartford. and Tim, I guess I need to borrow a world class +700wpc amp! Or whatever callibre of amp needed to surpass my 90wpc tube amps!

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. ( 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 :-)
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.

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.
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.

At 82 to 86 dB...loud, but not ridiculous.

SW X/O at 40 Hz...14 vrms and 21 volts peak.
which is 49 watts rms and 110 watts peak.

SW X/O at 100 Hz...12 vrms and 18 volts peak.
which is 36 watts rms and 81 watts peak.

Note the following facts.

1...SPL measured at middle of room about 12 feet from speakers. But, with Maggies, the SPL changes very little as you move away from the speakers.

2...SPL measured with SW operating. I don't have a convenient way to drive the Maggies full range (balanced/unbalanced interconnect issue). However, since Maggies roll off quickly (MG1.6 at 40 Hz) you might as well roll them off electronicly even if you dont use a SW. My findings apply to setups that do use a SW.

3...When the X/O was increased to 100 Hz, the highest rms voltage readings did not come down much, but most of the time the rms voltage was significantly decreased, to 3 or 4 vrms. This suggests that the peak power requirements were related to bursts of sound higher than 100 Hz, and so unaffected by the higher X/O frequency.

4...Music was a DVDA played in stereo, Emmylou Harris, Producer's cut, track 1, "If I could only win your love". Selected because there is limited dynamic range. (SPL doen't change much).

5...Radio Shack SPL meter. Digital readout. No guesswork.

6...All this is for MG1.6. Maybe someone having MG3.6 can contribute another test.

The following are opinions...

1...I suspect that the maximum short term (1 second) rms voltages were, or with different music could be, higher than the values that I caught with my voltmeter.

2...I suspect that the short term peak voltages could be higher than 1.5 times the rms.


1...If you use a subwoofer, and dont play Sousa marches or Wurlitzer theatre organ performances, a good 150 watt tube amp with good clipping recovery characteristics will work.

2...250 watts would be better.

3...My 600 watt amps are not overkill.

4...Sadly, the little inexpensive "Six Pac" triode amps, 55 watts, are out of the question for me.
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...Your experience is exactly what others have had. Perhaps my little test puts the lore on a solid technical footing.
Was Jvogt's improvement strictly due to the increase in power or the refinements brought on in Madrigal's amplifier design between the 27.5 and the 335? What exactly improved? .... less strain, more openness, more dynamics, etc. Details here would be of great value.
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.
I have no problems driving my Maggie 3A's with a Classe' 150. Prior to that I used a Classe' 101. I also owned 2A, which worked well with the 101 and a seventy.

I also have a Mac 275, which absolutely can not be used on the Maggies. Well, maybe if you only listen to vocal music and low volume.

I helped a friend put together a surround Maagie system with 2.5 and 2A's ccm3 center all with modified crossovers. They run on Classe' 101 and 100.

At one time, way back between 1986 and 1994 I ran 2A's on an Adcom 555, which never really worked well. Not enough current. When I bridge two 555's it worked much better.

I've never been able to afford a higher watt tube amps, i.e, 150 or more, to see what they Maggies could do but I would guess that you would need at least that many watts as well as and amp that could easily handle a four ohm load.