What does more power do for Magnepans?


I have Magnepan 3.5 speakers with a Plinius 9200 integrated. I think the sound is quite good but I always hear that Maggies love alot of power. I am curious and considering a Plinius P8 to biamp with the 9200. What difference could I expect to hear with more power? Any opinions?
Ag insider logo xs@2xpal
Dfhaleycko,

I will post impressions, but I think it would be better if I let Pal have his thread back and post to my system.

I haven't had a chance to sit down and listen for long periods. Too much work!!! I didn't expect a huge difference between horizontal and vertical with "identical" 2 channel amps (maybe not so "identical" after all). Just a little bit of extra headroom. But the presentation is different. Some talk of letting a system settle after changes. I am beginning to wonder if that isn't part of the difference.

I am going to run RTA when I get a chance and see if it measures slightly different. Will post the results.

Jim S.
Jim S wrote:
I made the change to a vertical biamp yesterday. It made a tremendous difference in presentation. Don’t know what to make of it yet.

--
Your results mirror mine. Vertical bi-amping rules! Or at least it's really different, and maybe better... Jury is still out.

I've been playing around with vertical bi-amping my Maggie 1.6's for the last month as well. Previously, I was horizontally bi-amping with an Innersound ESL-II at 600wpc into 4 ohms powering the bass panels and a McShane-modded 70wpc HK Citation II on the treble panels. I had carefully level-adjusted the two amps, using a RTA analyzer with a calibrated microphone, using a sweep generator to make sure the sound output was even across the frequency spectrum in my listening room, measured from my listening chair.

Even though I use an electronic crossover, I was concerned that I might be hearing phase anomalies with the mix of the two different amps. So I built a new modded Citation to match the first one. These tube amps have HUGE power transformers that will pass a clean 70kHz signal, very high quality! They seem to have enough power to do a credible job with the Maggies, especially since the amp outputs are connected directly to the drivers, with no inductors or capacitors in the signal path to soak up power.

Of course, 70 watts on each bass panel driver isn't all that compelling with Maggies, so I've also recently inserted a high-pass filter on the bass amps to cut off frequencies below 80Hz, which are handled by a pair of subwoofers. The amps seem to be quite happy with this load.

Gains: much more coherent image, but a somewhat thinner sound overall. Acoustic recordings and female vocalists are clearly more accurately reproduced. Piano is especially much more realistic.

Losses: I miss the iron grip that the Innersound had on the bass panels. I never used to feel the need for a subwoofer, but now it's mandatory, and the bass overall is a bit wooly, especially things like timpani.

Overall, I think vertical bi-amping with matched stereo amps has real potential with these speakers. However, if you want to do it with tubes, you face certain compromises in terms of full dynamics, or you need to spend megabucks for high-output tube amps. It seems silly to spend huge amounts for VTL-750's or whatever, but I think the resulting sound would be worth it! I haven't yet found a sand amp I like nearly as well on the mid/highs, but that certainly is next on my list to explore.

I'd be interested to hear your impressions after extended listening with your setup.
El,

Thanks. More coherent than I could of posted to Dan's question.

Dan... I went to active biamping for a couple of reasons. The 1.6's are reputed to benefit greatly from better crossover parts. My little Arcam Alpha 10's are 100w/8ohms 170w/4ohms and theoretically a little short of wattage at SPL levels I occasionally listen at. A Bryston 10B came up used at a good price, so let’s kill 2 birds with 1 stone. Improve the crossover with the Bryston (bypassing the stock) and get the best I can out of the little Arcams with active biamping.

After the change, it became obvious that I had been straining the amps through the stock crossovers. Clarity and control were immediately present and at much higher SPL’s. There is some reading available on the theory. I don’t really have a good enough grasp on the basics to completely understand all of the principals. In case you want to read it.

http://sound.westhost.com/biamp-vs-passive.htm
http://www.passlabs.com/products.htm (XVR1 manual)

Now the bad news... all those new and old pop/rock CD’s that I used to love so loud... well some of them aren’t so great when you can actually hear what is going on in the recording.

BTW – I made the change to a vertical biamp yesterday. It made a tremendous difference in presentation. Don’t know what to make of it yet.

Jim S.
Don_s...In a 2-way speaker system of,say, 8 ohms, each of the drivers will be 8 ohms. True, the drivers are in parallel, but because of the crossover the power amp "sees" the woofer alone at low frequency, and the tweeter alone at high frequency, so the overall impedance remains 8 ohms.

Biamping does increase the effective power of the amp. If you do not biamp the HF signal is riding on (superimposed on) the LF signal. The peak signal, which is what may cause the amp to distort, will be the sum of the two, If you biamp properly using an electronic crossover, each amp has only the HF or LF to deliver. The HF, for example, starts from zero, rather than where the LF signal is, and therefore has further to go before distortion results.

This power gain was important back in the days when 20 watt amps were the rule, but today it is simpler to just get a bigger amp. Also, in the old days, intermodulation distortion (which occurs when a HF and a LF are amplified together) was typically 1 percent or higher, and biamping helped. But today's amps have lower IM.

Today biamping remains useful, and almost universally used, for the subwoofer/main speaker crossover, because the inductors and capacitors needed for frequencies below 100 Hz are large and very expensive. The only advantage of biamping the main speaker is to avoid the passive crossover. Makes you wonder why some people simply hook up two amps without using an electronic crossover, and bypassing the built-in passive crossover.
Jim, I am unfamiliar with Maggies and I did not quite follow your measurement scenario so maybe I am missing something. But I did learn a lesson the hard way on my speakers. Adding a second amplifier (identical to the first) did not double the available power. I did gain the benefits of going to an active crossover vs a passive crossover but the small power gain was pretty much the result of the crossover type change, not the extra horsepower up front. And maybe there was no power gain at all and it was just the change in presentation from the crossover change. Anyway, the failure to increase power was a major surprise and disappointment but an excellent learning experience.

Consider this for a two-way speaker (considering one channel at a time). One amplifier sees the combined impedance of two drivers in parallel. That combined impedance is less than the impedance of the highest impedance driver. The amplifier will have a certain output into that impedance.

Add a second amplifier identical to the first. Each amplifier channel will see the impedance of a single driver. That impedance will be higher than two drivers in parallel and the amplifier output will be diminished.

If I got this wrong I would appreciate a gentle education. Those few members who continually post negative and critical comments need not respond.
El,

No, it is a digital multi-meter. Just slow to react. Less than $10 at RS.

To do total amp output I would have to undo the active biamp setup and reinstall the passive crossovers in the 1.6's. And get better measuring equipment! Your early results and postings gave me enough motivation to check the seperate panels driven by seperate amps. It was mostly just general curiosity.

But, I got a lot out of the little experiment. Learned a small fraction of electronics theory, its pratical application, and why there is so much potential in a vertical biamp setup with the Arcam/1.6 combo. Clearly, dividing the 2x+ current draw of the low frequency panels between the power supplies of a pair of 2 channel amps instead of using a single 2 channel amp and its power supply for the low frequencies has a great benefit potential. I think there is the potential for added IM distortion when running HF and LF through the same transformer in a vertical setup. We will see if I can hear it.

Here in Cincinnati, we are rained in today. Guess what I am going to do today. Go Vertical!

Then I got to quit fussing around with electronics and make some room treatments!

Jim S.
Stilljd...It appears that your voltmeter was the analog kind. Reading this when the signal is fluctuating would be difficult. My meter is digital. It makes a measurement about once a second. All I have to do is remember the highest value that I see over some reasonable test time.
For some things, digital is best!!

If you want something more to do, try making some measurement of the total amp output: not HF and LF separately.
Bob,

I set the volume pot at a level that I occasionally listen to and left it there. I was more interested in measuring at a known volume level to see how much juice the speakers were pulling.

They are both "modern" recordings (CD) and fairly close in "average" level. The D Warhols just has a ton more bass energy. So the peak SPL for that recording were probably higher.

If there is something specific your wondering about, I can rerun the little experiment and equalize volumes as best I can. Watching the little bar graph jump on a RS meter is not the most precise thing in the world. Nor is watching a fluctuating multi-meter. I also have some analysis software, but I don't know if it will measure a lengthy enough sample to find the peaks.

I have to learn to be careful in my statements here, too many sticklers for precision. This was just meant as an interesting observation, not accurate science.

Jim S.
Hi Jim, you said : Playing tracks of Allison Krauss (acoustic ensemble) and Dandy Warhols (bass heavy psychedelic) with fairly narrow dynamic ranges at levels I occasionally listen at… 93-95db peaks measured @ 11 feet (observed) produced these peak voltage readings (observed);

A. Krauss track
HF ~ 1.8 – 1.9 V
LF ~ 3.9 – 4.1 V

D. Warhols track
HF ~ 1.8 – 1.9 V
LF ~ 4.2 – 4.3 V

I was wondering if you adjusted/changed the volume levels for the two different songs when you obtained these measurements?

Bob
El,

I did make some measurements at lower SPL's and although I didn't make note the specifics, you are correct. Voltages go proportionately lower, by a bunch.

Also understand your point about rms vs. peak, and yes, that was a misstatement on my part.

The voltage differences between the 2 panels caught me off guard. I hadn’t reasoned through it properly… i.e – panel size, higher magnitude of excursion at the lower frequencies, etc.

93-95db… that is reading the bar graph on the RS meter. Lord knows what the real peaks are. Only ½ dozen or so songs that I can actually listen to that loud. It is overloading the large, sparsely treated room on 99.9% of music, and probably straining the amps on all music. But someone with an extensively treated, large room… I can see them pushing amplifiers to those kinds of voltages to get 90-91db peaks at the listening position and being quite comfortable at those volumes.

I know most here will yawn, but going through the reasoning and measurements the first time (like me) is fascinating and educational.

Best Regards,
Jim S.
Stilljd...93-95dB at 11 ft is indeed loud. I believe you are right about the voltages being ten times higher than you recorded due to meter scale error. 2.84 volts into these 4 ohm speakers would be only 2 watts.

I never tried to measure the woofer and tweeter sections separately, but your observation that the woofer takes a lot more is to be expected. While the voltage is about 2.2 times higher, the power is almost five times higher. Look at the areas of the woofer and tweeter sections, and the reason is obvious.

The RMS power rating of the appropriate amp would be based on the 43 volt rms reading, not the 60 volt estimated peak.
(43 * 43)/4 = 462 watts.
A 462 watt rms amp would need to swing up to 60 volts to avoid clipping a sine wave.

You might make some more measurements at a lower SPL. The
power requirements will be more reasonable. But I think you probably understand why some people (like me) have used 600 watt amps on these speakers.
Just to follow up. I got to sit down with a RS multi-meter, SPL meter, and check voltages at the speakers for different levels and kinds of music. Because the 1.6's are setup "active" (acoustic crossover is around 700 hz) I was able to easily measure the input into the high frequency and low frequency sections.

Playing tracks of Allison Krauss (acoustic ensemble) and Dandy Warhols (bass heavy psychedelic) with fairly narrow dynamic ranges at levels I occasionally listen at… 93-95db peaks measured @ 11 feet (observed) produced these peak voltage readings (observed);

A. Krauss track
HF ~ 1.8 – 1.9 V
LF ~ 3.9 – 4.1 V

D. Warhols track
HF ~ 1.8 – 1.9 V
LF ~ 4.2 – 4.3 V

In my limited understanding, these readings should be higher by a factor of 10, but I probably have a setting wrong on the multi-meter.

What struck me was the power consumed by the low frequency section of the 1.6’s. Twice the power was needed in the mid/bass panel over the QR section in both cases. This leads me to two observations.

I need to change from the current horizontal biamp to a vertical biamp. Both amps are the same Arcam Alpha 10’s and their transformers would probably benefit from sharing low frequency duties.

I might be able to use more, or cleaner, power to the speakers. 43V observed peak / .707 = 60V theoretical peak. 60V/4ohms = 15 amps. 15A x 60V = 900watts!!!!!! In one channel! The Arcams are 170W@4Ohms. Active is supposedly 4X, so it works out to about 680 watts. Not to mention we are on a 15 amp circuit.

Not the end of the discussion by any means. But interesting.

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

_____________
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?
____________

Of course there was a lot of follow-on discussion that may be of interest.
I think I have corrected a couple of mistakes. Still ignores room loading, absorption, and full spectrum of frequencies.

86db/1m/2.83V = 86bd/1m/2w. Not 83db/1m/2w.

If you listen at a level that produces 96db peaks it would go something like this…

2w/1m = 86db with one speaker
Second speaker adds 3db for 2w/1m = 89db
Subtract 3db for each doubling of distance away from speakers. 3m = – 5db, or 2w/3m = 84db
Double the power requirements for each additional 3db;
4w/3m = 87db,
8w/3m = 90db,
16w/3m = 93db,
32w/3m = 96db.

32w. Not a lot of power for what, to me, is a fairly loud 96db peak.

I sat down yesterday and checked the SPL’s at the levels I listen. Loud to me is measured peaks at 85db on a RS meter. There may be unmeasured spikes in there from transients, but certainly no higher than 90db.

The reason this intrigues me is; I recently went to an active biamp setup from a passive biamp on 1.6’s with rather startling improvements. Much greater clarity and coherence all around, and at higher volumes. Having started on the more power helps bandwagon, I have being looking to pull the trigger on more powerful amps than the current 170w Arcams’ that I own (probably better quality too).

I want to be “smart” about it, but the analysis on paper doesn’t match my limited experience. No substitute for auditioning to learn is there?

Jim S.
Thanks Bob,

A fundemental misunderstanding on my part. Does change the result, doesn't it!

Jim S.
The biggest problem with that calculation is that to obtain a subjective doubling of loudness requires ten times the amplifier power. See: (http://www.gcaudio.com/resources/howtos/voltageloudness.html)
One thing wrong with your calculation. One subtracts 3db for every doubling of the distance, therefore 2m=-3db, then 4m=-6db, not 3m=-6db. 3m would be close to -5db, I suspect.

Bob P.
I tried to go back and study some of the math about maggies and power. These were pointed out by others; I am just trying to pass on their work and analysis correctly.

First thing I ran across was the way Magnepan spec's the efficiency. 86db/1m/2.83V. Evidently 2.83V into 4ohms is 2 watts and not the traditional ~db/1m/1w scale. At 1m/2w efficiency works out to 83db.

If you listen to music at a level that produces 83db peaks (fairly restrained, but still dynamic) and sit 3 meters away it flows like this.

2w/1m = 83db with one speaker
Second speaker adds 3db for 2w/1m = 86db
Subtract 3db for each additional meter away from the speakers 2w/3m = 80db
Each additional 3db doubles power required - to add 3db – 4w/3m = 83db
Figure the peaks @ 83db are 6db above the average spl = 1w/3m/76db

This ignores room loading, absorption, and the fact that the 2w/1m/83db is with a test tone, but on the surface, the amount of power needed doesn’t seem that great for modest listening levels.

If you listen at a level that produces 95db peaks it would go something like this…

2w/1m = 83db with one speaker
Second speaker adds 3db for 2w/1m = 86db
Subtract 3db for each additional meter away from the speakers 2w/3m = 80db
Double power for each additional 3db;
4w/3m = 83db,
8w/3m = 86db,
16w/3m = 89db,
32w/3m = 92db,
64w/3m = 95db

64w. Still not a lot of power for what, to me, is a fairly loud 95db peak.

It doesn’t match my (admittedly limited) experience, so I am fairly assured that I have stated something incorrectly or there is another important factor that is missing.

You won’t hurt my feelings by pointing out the flaws in the above but I do find the result interesting if it holds true

Jim S.
i listen to orcehstral as well as small ensembles. i just don't listen loud and low power amps seem to work for me.
Mr. T,

Wasn't picking on you, just wondered. About where I sit from my 1.6's.

I know you like solo and small ensemble acoustic music and evidently the smaller tube amps work well for you. It is just so opposite from my (I will admit, limited) experience.

I went from single 170w integrated, to two 170w amps in a passive biamp, and finally two 170w amps in an active biamp configuration and enjoyed an improvement with each addition of power.

Different strokes for different folks!

Jim S.
I've been playing around with different amps for the last eight years on my Maggie 1.6's. Reluctantly, I've moved into the more power camp during that period.

I started with Classe CA150 power amp (300wpc into 4 ohms). I was happy for a long time. Then I was modding an old Dynaco Stereo 70 that I had built new in high school (using the Welborne/Alan Kimmel driver stage). On a lark, I tried it on the Maggies, and I was BLOWN AWAY by how much better they sounded with this little 25wpc amp.

I couldn't believe how much more "real" vocalists sounded, in particular. And chamber music was to die for. I sold my Classe in a heartbeat. But then I discovered that all my listening was gravitating to small-scale stuff, because that's what my system did best. And I LIKE symphonies... but not with the Dynaco. So I have some sympathy for Mrtennis' position.

I added a subwoofer, and inserted a high-pass filter, so the poor little Dynaco wouldn't have to do any bass below 80Hz. That was a Great sound, and even OK on larger scale music.

But I wanted more... (don't we all?)

I decided to mod my crossovers, and added Mye stands, both of which were huge improvements. Then I decided to try bi-amping, with one tube amp on the bass panels (60wpc) and the Dynaco on the treble panels. This was also really nice, and kept me for a couple of years.

Then I had a power surge (lightning strike) and toasted both amps. While I was getting them fixed, I put in an Innersound ESL amp, which delivers 600wpc into 4 ohms. NOW WE'RE TALKING when it comes to large-scale music. Symphonies were back, and in high rotation for months. Love that detail and resolution, no lack of foundation. I didn't bother with the subwoofer.

Now I'm back to bi-amping, but with the Innersound on the bass panels and a modded Citation II on the treble/mid panels. I'm really happy with this combination, both finesse and power. I don't need a subwoofer, and I've got excellent integration across the frequency spectrum for all the kinds of music I listen to.

This is not a discussion of tubes vs. solid state, but I do think you should try more power (of high quality) and see what you think. I love what the Maggie bass panels do with lots of power. I love what the treble/mids do with high-quality "first 2 watts" This is a combo that works for me. YMMV.

HTH!
Pa1- I really do think you will be surprised at how relieving your amp of having to reproduce bass/mid-bass can clean and open up your overall sound. Can you find a dealer that will let you audition one for a week or better? That would give you time to burn it in a bit before listening critically.
Thanks for all the input! I do use two sets of cables to biwire and the speakers sound very good. You know how this hobby is, I wonder what if? The P8 would be a perfect match for the 9200 to bi amp but I probably don't need it, but who knows I might try it anyway.
I agree with Valleyplastic. By running 2 sets of cables per side, one pair to the bass and a separate run to the mids and highs there’s a huge improvement as was mentioned.
my listening position is about 10.5 feet from the adge of the right speaker.
02-22-08: Zippyy
"That's because an Elephants trunk contains over 40,000 muscles"

I guess that sums it up then...more muscle can be a good thing for Maggies, and Elephants.

Dave
Mr. T,

Just how close do you sit to your 1.6's to get 72 - 82db with 4 watts?

Jim S.
Rf_gumby..."As you add devices to gain power, you lose delicacy, kind of a trade off".

This has been repeated so many time that it's almost become true! Have you ever seen an elephant dance? Or manipulate things, like a paint brush, with delicacy you wouldn't expect from that huge trunk.
Your 9200 has more than enough power, current and finesse. Put your money towards something else.
Your 9200 has pre-outs and 200wpc. If you were to purchase a Plinius P10(also 200wpc) you could bi-amp very simply. Magnepan offers an optional bi-amp x-over for the 3.6/R, and I'll bet one is also available for the 3.5. You might give them a call and check.
I've powered my 1.6 speakers with as little as 35 watts and as much as 200+ watts of class A power. Low power is fine as long as it is high current and you listen to voice or small jazz and chamber groups. If you have a large orchestral piece that has great dynamic range you will want plenty of high current power. I have no doubt that you can get wonderful sound with a few watts but I believe some music requires more current and power or the maggies will sound congested. I'd rather go with high current, high power amplification (SS) and a good tube preamp.
how is a speaker driven to hard with a 30 watt power amp at 72 db, if for example it is rated at 85 db/1 watt/1 meter ?
i would understand trying to produce 85 + db, subject to room size as perhaps being a problem, but not 72db.
not so much higher decibel levels. But more power will protect the speaker form being driven to hard with a lower power amp.
It's not about loudness, it's about controlling the panels. Tubes have a more difficult time doing this. Therefore, more tubes in parallel whether it's push/pull or single ended, lowers the output impedance,(plus or minus an output transformer). Dampening factor doesn't seem to quite explain it either. It's got to do with realism... With tubes, you'll simply need a ton of watts.
As you add devices to gain power, you lose delicacy, kind of a trade off.

With 3.5's I vastly preferred 200 wpc over 100 wpc when using solid state. Same series of amps, both new, just the power difference. I also performed this test with 2 different brands of amps with the same result.

The 1.6's are far easier to drive than 3's or 20's. yes, I've heard 3.5's with 35 watts, I've heard them with 4 watts, while the 35 watts was almost acceptable, it just didn't do it for me. My room is rather large for panels
though, so your results may vary.

Try your 3.5's with a borrowed 50 watt amp, see if you like it. That may help give you more perspective.

Good luck.
hi narrod:

thick and gooey means severely attenuated treble and highly palpable midrange.
For an understanding of audio output in db, and power requirement, read this:(http://www.axiomaudio.com/power.html) It would be nice if doubling the perceived sound only required doubling the power. The least I've powered Maggies with was a slightly modded Dynaco ST-70(about 17W a side in reality). Yes- They sounded nice, but realism could only be approached listening to small acoustic sets. Remember that you're driving a nominal 4ohms too, and look at your amp's output into that load before you shop for power. I'm trying to think of ANY live music I've heard in the last 48yrs that was, "lush, thick and gooey." Was it the 'Hot Fudge Sundaes'? NO-that was at Baskin-Robbins. Hmmm, let's see.......
"it's too bad you weren't at an audio meeting when i demonstrated the 1.6s with a 4 watt amp."

As I said, there is no wrong answer but, rather, what each of us like. I like low powered amps with efficient speakers but not with planars. I don't know what "thick and gooey" means when it comes to a description of sound.
I think it's more about control of those panels than power. I had a friend drop off his hovland sapphire for use on my maggies and it just fell flat - and that was at low moderate volumes. It wasn't a question of enough watts. My ps audio hca-2 sounded clearer, more open...better. I really wanted the tubes to sound better because I am a tube lover, but for me it wasn't happening.

Mr. Tennis, lush, thick and gooey? Not really selling me with that description.
hi narrod:

it's too bad you weren't at an audio meeting when i demonstrated the 1.6s with a 4 watt amp. i would have given you a barf bag, or you might have passed out. it was the best sound i heard from those speakers. bernadette peters sol rendition of "blackbird" was lush, thick and gooey. wonderful !!
We like what we like. There is no wrong answer. I've heard Magnepans (I have 1.6s and have owned 1.4s and 2.7s)) with low power and hated the presentation. I wouldn't own them if I couldn't drive them with lots of clean power.
One way to make dipole bass, sound more like monopole bass...(which has more punch and slam), is to apply HUGE amounts of power to the dipole bass panel.

In truth, and fact...it still does not work. If you need slam and boom...stick with large cones. Dipole bass does not interact with the air, in the same manor that large cone monopoles do...more, and more power can not change this to any large degree.

Dipole subwoofers, will never have a large market share, in the subwoofer market.

My advice...don't buy used Maggies (or others of the type) from anyone who advocates the "more power is always better theory". In truth, these people have bought the wrong speaker type for their needs...and usually move on after a large dose of frustration. The bass panels will need repair much sooner on these, than those which were not abused in the same manner.

Dipole bass is about quality, not quantity....although, you can have a very large degree of both here, if you do it right....(large monopole subwoofers).

Dave
Mrtennis is correct that Maggies sound great with low power amps. But Brownsfan is also correct that a high powered amp will show you another level of performance. This is not the case with all speakers, and accounts for the myth that Maggies absolutely need many watts. It's not about loudness. I don't know why this is, but it's real.
I have the 9200 with the 1.6 Maggies. For months I have run one set of speaker cables to the 1.6 which I had Cardas jumpers on. Last week I decided to run 2 sets of speaker cables to each speaker and eliminate the jumper.
It's easy with the 9200 as there are 4 sets of binding post, 2 for the left and 2 for the right. Run one set to the highs and the other to the lows. This alone improved low end, detail, sound stage, etc. I do not like Bi-wire, I prefer to run 2 sets of cables.
I found by doing this I had to turn my volume down to what it was in the past.
This was a huge improvement across the board.
Your 3.5 or even the 3.6 I know is different but I know when the time is right I will try the 3.6 but will keep my 9200 ( I think )
I agree with Mrtennis: I first heard the 3.6 with a 35 watt Audio Research tube amp and could not believe the sound. When I asked about power and why so little I was told that in a very large room, grated you may want more power but you mainly want and need a amp that is high current. Power takes the back seat.
If you are using stock feet that came with the speakers I would highly recommend you consider the MYE stands. This alone was a nice improvement.
Also, what speaker cable are you using ?