[medium jim]

Not sure if this has been prior posted, nevertheless, it is useful:

http://www.integracoustics.com/MUG/MUG/articles/speakers.html

Jim

[josh358]

It is useful, but use caution -- not all of the information is correct.

[medium jim]

It is useful, but use caution -- not all of the information is correct.

Only a guide, but you are correct about there being some errors, for instance the 2.5R's show a sensitivity of 84db, when I called Magnepan I was told that they were 86db in the chamber and around 88db in most normal rooms. 

Nevertheless, a good starting point.

Jim

[Letitroll98]

I've seen the chart, but not on AC, a good addition.

[Roger Gustavsson]

Only a guide, but you are correct about there being some errors, for instance the 2.5R's show a sensitivity of 84db, when I called Magnepan I was told that they were 86db in the chamber and around 88db in most normal rooms. 

Nevertheless, a good starting point.

Jim

Well, the figures from Magnepan are a bit optimistic. My own MG 3.6 is about 5 dB below my other well documented speakers which give 87 dB for 2.83 V of input. I have made the comparsion in my sweet spot.

[Letitroll98]

I think the measurement is to be taken at 1 meter, unless I'm wrong.

[Davey]

The Magnepan sensitivity figures have been confusing since day one.....and they still are.  It doesn't help that they advertise a 2 watt sensitivity vice a 1 watt number, which is more or less an industry standard.  And all but the biggest models don't have the theoretical -3db/doubling-distance advantage associated with "near-field" SPL drop off.

However, unless you've had your head buried in the sand, you know that Maggie speakers are horribly inefficient.  So, you know that going in and can base a power amplifier decision on that fact.

Cheers,

Dave.

[medium jim]

The Magnepan sensitivity figures have been confusing since day one.....and they still are.  It doesn't help that they advertise a 2 watt sensitivity vice a 1 watt number, which is more or less an industry standard.  And all but the biggest models don't have the theoretical -3db/doubling-distance advantage associated with "near-field" SPL drop off.

However, unless you've had your head buried in the sand, you know that Maggie speakers are horribly inefficient.  So, you know that going in and can base a power amplifier decision on that fact.

Cheers,

Dave.

More confusing is that the measurements are in an Anechoic Chamber (an industry standard) and do not replicate real world rooms which usually are more acoustically lively.  Clearly, Dipoles/planars infuse energy into rooms much differently than box speakers and maybe a different reference standard needs to be conceived and implemented to level the playing field.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&ved=0CDAQFjAA&url=http%3A%2F%2Fwww.ece.utah.edu%2Fuploads%2Fresearch%2Fstudent_labs%2FAnechoic%2520Chamber%2520Tutorial.pdf&ei=39-HUa3eEeTbigL4uoDQDw&usg=AFQjCNEz1efX21pF1GgN-VGn6pMKZDb6pg&sig2=GnkeQ_NI7iYPkKxrX3DOsA&bvm=bv.45960087,d.cGE

http://en.wikipedia.org/wiki/Antenna_measurement

Jim

[josh358]

More confusing is that the measurements are in an Anechoic Chamber (an industry standard) and do not replicate real world rooms which usually are more acoustically lively.  Clearly, Dipoles/planars infuse energy into rooms much differently than box speakers and maybe a different reference standard needs to be conceived and implemented to level the playing field.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&ved=0CDAQFjAA&url=http%3A%2F%2Fwww.ece.utah.edu%2Fuploads%2Fresearch%2Fstudent_labs%2FAnechoic%2520Chamber%2520Tutorial.pdf&ei=39-HUa3eEeTbigL4uoDQDw&usg=AFQjCNEz1efX21pF1GgN-VGn6pMKZDb6pg&sig2=GnkeQ_NI7iYPkKxrX3DOsA&bvm=bv.45960087,d.cGE

http://en.wikipedia.org/wiki/Antenna_measurement

Jim

If you look around online you'll find an SPL calculator that takes into account both the lower room gain of dipoles and the 1/R radiation pattern of tall line sources. (I'd give you the URL but I don't remember where I saw it.)

[josh358]

The Magnepan sensitivity figures have been confusing since day one.....and they still are.  It doesn't help that they advertise a 2 watt sensitivity vice a 1 watt number, which is more or less an industry standard.  And all but the biggest models don't have the theoretical -3db/doubling-distance advantage associated with "near-field" SPL drop off.

However, unless you've had your head buried in the sand, you know that Maggie speakers are horribly inefficient.  So, you know that going in and can base a power amplifier decision on that fact.

Cheers,

Dave.

I think the idea is that expressing the sensitivity as a function of voltage rather than power benefits 4 ohm speakers.

[medium jim]

If you look around online you'll find an SPL calculator that takes into account both the lower room gain of dipoles and the 1/R radiation pattern of tall line sources. (I'd give you the URL but I don't remember where I saw it.)

Josh:

That would be really useful.  BTW, I spoke with Wendell today and he said there is no difference between the 2.5 and 2.6 with regard to their sensitivity. This confirms what I suspected.

Jim