[a.wayne]

AB transistor amps, putting them on a bathroom scale is probably more useful than the RMS spec.

This goes for all amps ........

[Davey]

As a further experiment, I attached an adjustable pad to the input of my oscilloscope to create a +/-50 volt monitoring window.  (100 volts P-P is equivalent to a 150wpc / 8 ohm amplifier.)
I had my MMG system playing for a few hours with a variety of music (loud) and no musical peaks were even close to exceeding that window.

AC members can believe whatever they want I guess, but that's my firsthand experience with MMG's and power.

Dave.

[a.wayne]

Dave ,

What amplifier are you driving your MMG with ....

[mcgsxr]

Dave, having owned and enjoyed a set of the MMG myself - what would the 4 ohm equivalent be? 

You reference the 8 ohm 100v so I wonder what the 4 ohm rating would be.

I don't doubt that my Crown puts out way more than I need but it is affordable and it sounds good to me. 

[Davey]

The type/brand of amplifier I'm using is irrelevant.
All that matters is that it has a power rating equal to (or greater than) the 150wpc rating we're concentrating on here.  And it does....easily.

mcgsxr,

We're analyzing (much more so) the voltage swing capability here.  That aspect/limitation will not change whether you have a 4 ohm speaker or 8 ohm speaker.  A 4 ohm speaker would draw double the current, and thus double the wattage, but the voltage waveform will still look the same.  "Clipping", in this context, is referring to a voltage limitation.

I'm sure your Crown amplifier has sufficient power available and will not voltage clip under any conditions.
Whether or not it sounds good, or exhibits some other subjective traits that we might like (or not like) is beside the point and another discussion completely. 

Dave.

[mcgsxr]

Got it, thanks Davey. 

[Davey]

Its a discussion , the type of amp was just for reference , i thought  you said it was 25 watts / ch , so its more than 150 @4 obm ? Anyway , no its not irrelevant to know ..

It's not even a discussion.  I was simply relating the setup I used to evaluate the peak levels provided to my MMG's under loud conditions.
I never mentioned using a 25 watt per channel amplifier.  Please read my posts again.
This particular amplifier is 250 wpc, but I also have a 75 wpc amplifier I've used successfully on the MMG's for a few years.  (It doesn't clip under loud conditions either.) 

As I said, the type/brand are irrelevant.  As long as the amp functions as a voltage source this type of evaluation is perfectly valid.
 
Dave.

[sfdoddsy]

I recall reading somewhere that the sound of a real orchestra in a real hall peaks at about 90db. Nowhere near what what people suspect.

Movies are different of course, but even then the 120dB THX spec is for short term peaks.

I've done SPL readings of my system, and 90db is very loud. I got to 100db once or twice listening to movies and it was insanely loud.

As for Maggies, I've had a few over the years and driven them with everything from Crown pro amps, to cheap-ass receivers, to audiophile approved power amps. I have a set of MC1s set up at the moment and have tried all of the above. All will drive them to louder levels than I like to listen to.

I'm also talking big stressful symphonies. My usual test is the opening to Mahler's 5th.

None of them sound discernibly different.

[josh358]

I recall reading somewhere that the sound of a real orchestra in a real hall peaks at about 90db. Nowhere near what what people suspect.

Movies are different of course, but even then the 120dB THX spec is for short term peaks.

I've done SPL readings of my system, and 90db is very loud. I got to 100db once or twice listening to movies and it was insanely loud.

As for Maggies, I've had a few over the years and driven them with everything from Crown pro amps, to cheap-ass receivers, to audiophile approved power amps. I have a set of MC1s set up at the moment and have tried all of the above. All will drive them to louder levels than I like to listen to.

I'm also talking big stressful symphonies. My usual test is the opening to Mahler's 5th.

None of them sound discernibly different.

Acoustical music can actually be much louder than that. Check out this histogram, you'll see that measured peak levels on performances of acoustical music were as high as 127 dB:




It's from Felder's excellent paper on dynamic range requirements for digital audio:

http://www.zainea.com/Dynamic%20range.htm

For most classical performances, 120 dB at the listener's seat is probably adequate. Most conventional consumer loudspeakers can't do this, but some of the big ones can.

I'd add that that these are peak measurements, if you're using an averaging SPL meter you have to add 10 or even 20 dB to account for peak to average ratio. This causes a *lot* of confusion. Also, that this isn't about subjective loudness. Subjective loudness is based on averaging (which is why VU meters were designed to have averaging rather than peak characteristics) and so just about any system can play acoustical music as loud as any other. What you'll get with most consumer systems though is a sense of strain and peak compression/clipping. Whereas if you go into the studio or listen to the rare consumer speaker with high output, you don't get that.

[Davey]

Josh,

Paul's original comment here was based on a subjective evaluation.....and not really related to power.

Anyways, I think live versus domestic-reproduced SPL's, peak versus average, speaker compression....is a different topic, relatively speaking.

The interesting questions here are......(and what the thread devolved to).....
1. How loud would a user ever possibly play his speakers in his room with his music?
2. Does his power amplifier support that playback level without voltage clipping?

The answer to #2 is a simple yes or no.  (In my opinion.)
And I've offered a simple oscilloscope experiment to evaluate it.  FWIW.

Cheers,

Dave.

[a.wayne]

I recall reading somewhere that the sound of a real orchestra in a real hall peaks at about 90db. Nowhere near what what people suspect.

I have measured , 112db row 11 center full symphony and it depends , Carmina Burana  Live will exceed this easily, no sound system  can match.


Amp designer Bob Cordell offered a simple experiment ( not conjecture) at an Audio Show and witnessed by a few hundred individuals, i had posted the link earlier and he captures what is required ( speakers 89db/1 watt) and why most Hi -F systems are considered under powered for their application. No accident SOTA systems are using big amplifiers , big speakers with high ( 90+db/1 watt) sensitivities.  Maggie 3.6r has a measured sensitivity of 83db /2 watts or 80db/1W, it's by no accident owners jump for Joy when they are fed 300- 600 watts ...



Regards..



http://www.cordellaudio.com/

[Davey]

I have measured , 112db row 11 center full symphony and it depends , Carmina Burana  Live will exceed this easily, no sound system  can match.

Simply not true.  A number of people have approached the domestic listening environment from a maximum SPL point of view.  Some of these systems you might not enjoy listening to because of some other aspect, but they CAN achieve ear-splitting sound pressure levels.  Usually horns are involved. 

I've listened to a couple myself.  Not an experience I enjoyed but, objectively, they can certainly reproduce painful SP levels cleanly.

Dave.

[josh358]

Josh,

Paul's original comment here was based on a subjective evaluation.....and not really related to power.

Anyways, I think live versus domestic-reproduced SPL's, peak versus average, speaker compression....is a different topic, relatively speaking.

The interesting questions here are......(and what the thread devolved to).....
1. How loud would a user ever possibly play his speakers in his room with his music?
2. Does his power amplifier support that playback level without voltage clipping?

The answer to #2 is a simple yes or no.  (In my opinion.)
And I've offered a simple oscilloscope experiment to evaluate it.  FWIW.

Cheers,

Dave.

i agree -- I linked to the Felder paper because I think the info is interesting, not because I think amp selection should be guided by it. I know people who listen at 120 dB, e.g., Satie, and I know people who never get to 90. No reason to get an amp bigger than you need or that's too small and will clip, and the best way to determine that is to measure.

[Davey]

I asked a question earlier in this thread which nobody answered.  I think it's key to this discussion.
Maybe somebody would like to take a crack at it??? 

Dave.

[a.wayne]

On DIYAudio , Pano  had made a very simple experiment , requires you to download his test signal and then measure voltage after playing your system at your usual loudest level. It does not account for crest factors so proceed with caution...


The large power output is for dynamic peaks , since most domestic listen will be in the 1-3 watt level (4-8 watt on maggie type sensitivity) If using SS, they are sonically at their best in the 30-37% range of their max rated outputs. SO if you typically see 100watts watts on peaks a 300 watt may subjectively sound better to you than a 120 watter.

80db/M/1 watt speaker is a no brainer for needing power to  not have dynamic compression , where  the worst case is hardness..


Regards...

[josh358]

Here's another histogram from the Felder paper, this one of consumer loudspeaker peak SPL's, taken from reviews in Audio Magazine. it shows that they cover the gamut:



Horns and big loudspeakers like the Wilson are probably going to be at the top, with dynamics low to middle and planars lower to middle. So it depends very much on the speaker.

Pro monitors typically do 120 dB +.

[a.wayne]

At 90db/Meter a 1.7 is exhibiting  approx 10% thd below 1K ................................

[josh358]

At 90db/Meter a 1.7 is exhibiting  approx 10% thd below 1K ................................

Doesn't surprise me, as I said, my MMG's started sounding stressed when the (non-peak Radio Shack) meter was in the 90's. This is why I got Tympanis! My old 1D's would play quite loud indeed and I'm hoping the modified IVa's will do the same, although in my dotage I don't listen at the levels I used to -- I want to keep what's left of my hearing. The Tympanis I thought were a good compromise between the detail of an electrostatic and the slam of a dynamic. (And of course the 3.7's and particularly the 20.7's will play louder than the 1.7 as well.)

BTW, both anecdote and measurement suggest that bracing the woofer panels, e.g., with a Mye stand, will add significant bass output -- an awful lot of energy is being stored in those vibrating frames -- and make the speakers sound cleaner too. And offloading bass as Davey has done with his MMG's will also increase max output, particularly on the smaller units.