[AmpDesigner333]

I can get into more depth on this later, but we were testing a prototype of a switching power supply driven MEGAschino MK2, and when going from the JTR 212RT to the Magnepan 1.7i, the volume was suddenly super low. I’m accustomed to this, so I just turned up the volume.  I was playing some tracks that aren’t recorded very loud and had to turn the volume all the way up to compensate.  My tech asked “What’s going on here?”, so I explained the math....

JTRs -- 101dB sensitivity
Mags -- 86dB sensitivity
Difference -- 15dB

Every doubling in power results in a 3dB increase in SPL.  15dB is therefore 5 “doublings”, and 2^5 is 32.  Therefore, it takes 32x the power to get the same SPL from the Mags!!

[FullRangeMan]

Great post, the current iphone generation dont know it 
We audiophools are being fooled for decades with awful low sensitivity and low impedance speakers except Klipsch and a few others.

[zapper7]

That begs the question....Can we believe all the specs on efficiency from the manufacturers? I can see possibly Klipsch and the like as it's been more or less proven over yaers of actual in home results, but what about some of the others?

[vrao81]

Many times I've seen John Atkinson measure a speaker's sensitivity and found it to be lower than the manufacturer's claimed value.

[AmpDesigner333]

Great post, the current iphone generation dont know it 
We audiophools are being fooled for decades with awful low sensitivity and low impedance speakers except Klipsch and a few others.

Lower efficiency leaves more “room” for contouring of driver response, so in general, it’s easier to make an accurate speaker of lower efficiency.  However, the JTRs have the lowest overall THD I’ve measured to date.  This doesn’t imply a flat response, but they have that, too, and they go lower (significant response below 20Hz) than any full range speaker I’ve had so far.

I’ll measure the output on the same system using a reference track at 1kHz.  We’re crazy busy at the moment so even writing this is taking precious time from some pressing matters.

One other thing I wanted to mention....  in my current setup, the Mags are almost twice as close to the listener compared to the JTRs.  That should provide 6dB more (so now we’re down to 8x the power).

A great tool for those interested in the calculations:
http://www.hometheaterengineering.com/splcalculator.html

[Dieterle Tool]

Great post, the current iphone generation dont know it 

No, but there's an app for it. 

-Dieter

[JLM]

With all the digital power amps out there loudspeaker efficiency is less of an issue as it once was.  Back when Klipsch was starting out 5 watt tube amps were the norm, so there was more interest in exaggerating efficiency ratings.  Plus there is more to efficiency than the ratings.  Many vendors use a simple 1 kHz signal, but what about a complex real world music signal?  And what about efficiency losses caused by complex crossovers?  And don't forget F3 ratings versus the flatness rating (that are two separate things).  And what about dispersion drop off? 

So an "honest" efficiency rating is not easily obtained. 

[Early B.]

What are the sonic implications of higher or lower efficiency, if any, particularly if you have more than enough power? For instance, I've heard many times that high-efficiency speakers are generally more dynamic. Any truth to that? 

[AmpDesigner333]

Ok, so I measured 89.2dB at 1kHz on the JTRs, and 78.9dB on the Mags.  That’s at a distance of 11.5 ft vs 8 ft.

The difference would be 10.3dB, BUT, the added distance to the JTRs lowers the SPL another 3.2dB for a total difference of 13.5dB, only 1.5 dB from the manufacturer’s specs.

However, the two might not be specified the same way (2.83V vs 1W, 1m vs 3 ft, etc.).  Another thing is that I remember testing the JTR 210RT model last year, and the specified SPL was roughly 2dB more than I calculated, so I looked into it, and they specify SPL at 2.0Vrms.  When using voltage instead of power, a 4Ω speaker gets a 3dB boost, but 2.83V/2.0V is 1.5dB !!

This has been a fun exercise (:   Maybe I’ll test some other speakers the same way someday soon since it’s pretty quick.

[lokie]

I'm at 99db and will not be going backwards in efficiency. But, kind of stuck where I'm at.

That is kind of the ceiling with direct radiators. Most HE direct radiators only have a horn down to around the 1kHz range.

To get higher efficiency than that, you need to implement bass horns which is a whole nudder kettle of fish. There are even more dramatic differences at that point but lots of problems for domestic use. 

[RonN5]

Here is the point that I don't get.  So, ok, the maggies and the jtr's are substantially different in sensitivity.  But, it is no problem to get quality watts to drive both of the speakers to an 85db peak for listening to music (not talking home theater). 

Assuming you are at your listening position 11 feet back and have set the volume control so that each speaker is at a peak volume of 85db (and that your amp still has plenty of headroom)....do the jtr's sound more dynamic...and if so why?

[FullRangeMan]

Lower efficiency leaves more “room” for contouring of driver response, so in general, it’s easier to make an accurate speaker of lower efficiency.

Yes, unfortunately they do it, an disrespect to the composer and the music. Even worse they do it with the xover, they dont even bother to shape the music with the internal stuffing of the box.

[FullRangeMan]

What are the sonic implications of higher or lower efficiency, if any, particularly if you have more than enough power? For instance, I've heard many times that high-efficiency speakers are generally more dynamic. Any truth to that?

In all my experience and with DIYers and top money audiophiles I have talked hi efficiency speakers are always better, more dinamic, faster transients and allow to use a inexpénsive low power amp what usually are a SET tube amp.

[sebrof]

Interesting article:

https://www.linkedin.com/pulse/power-compression-vs-thermal-distortion-loudspeaker-alexander-wilson/

[Tyson]

Here is the point that I don't get.  So, ok, the maggies and the jtr's are substantially different in sensitivity.  But, it is no problem to get quality watts to drive both of the speakers to an 85db peak for listening to music (not talking home theater). 

Assuming you are at your listening position 11 feet back and have set the volume control so that each speaker is at a peak volume of 85db (and that your amp still has plenty of headroom)....do the jtr's sound more dynamic...and if so why?

I used to own several very nice low sensitivity speakers (mostly using danish drivers), and have gradually moved away from lower sensitivity speakers and into speakers with higher efficiency.  For a couple of reasons.  First, more efficient speakers open up more interesting possibilities re: amps.  Tube amps, sure, but also lower powered SS amps like my beloved First Watt (Pass) BA3 amp. 

Second reason is high efficiency speakers just sound more like real instruments to me.  There's a dynamic life and engagement that I've just never heard with lower efficiency speakers.  And I don't mean just big dynamic swings.  I mean more the micro bursts of energy at the medium and quiet parts.  It's just incredible.

[Early B.]

I used to own several very nice low sensitivity speakers (mostly using danish drivers), and have gradually moved away from lower sensitivity speakers and into speakers with higher efficiency.  For a couple of reasons.  First, more efficient speakers open up more interesting possibilities re: amps.  Tube amps, sure, but also lower powered SS amps like my beloved First Watt (Pass) BA3 amp. 

Second reason is high efficiency speakers just sound more like real instruments to me.  There's a dynamic life and engagement that I've just never heard with lower efficiency speakers.  And I don't mean just big dynamic swings.  I mean more the micro bursts of energy at the medium and quiet parts.  It's just incredible.

Wow -- this is very significant. I can understand why -- higher sensitivity midranges and woofers tend to have less cone movement. If woofers are woofin' too much, that will diminish the clarity and mess up the entire sound spectrum. That's probably why a well conceived servo system provides cleaner sound.
 

[mocenigo]

In all my experience and with DIYers and top money audiophiles I have talked hi efficiency speakers are always better, more dinamic, faster transients and allow to use a inexpénsive low power amp what usually are a SET tube amp.

I think the main reason is that low efficiency speakers need more power from the amplifiers, and in peaks, resp. transients this can be critical, leading to a loss of macro dynamics, resp. micro dynamics.

Also, higher efficiency transducers usually have lower moving mass, which contributes to faster response. They dissipate less heat when listening at normal listening levels.  If the coil and the crossover components get warmer then their operating parameters will change. So there may be also an intrinsic reason.

[Craig B]

On the other hand, given the same amp and preamp, significantly more efficient speakers reduce the degree of fine volume control available to the listener at lower SPLs, especially if the volume control is stepped. That can be a nuisance.

[Tyson]

On the other hand, given the same amp and preamp, significantly more efficient speakers reduce the degree of fine volume control available to the listener at lower SPLs, especially if the volume control is stepped. That can be a nuisance.

That's true.  It'll depend upon the amount of gain your preamp and amp have.  If both are high gain, that's going to be an issue with high efficiency speakers.  One way around this is to get gear that's medium or low gain.

[AmpDesigner333]

On the other hand, given the same amp and preamp, significantly more efficient speakers reduce the degree of fine volume control available to the listener at lower SPLs, especially if the volume control is stepped. That can be a nuisance.

Our Maraschino monoblocks and x-CHerry multi-channel series of amps have 22dB gain.  This helps with the volume issue and allows more use of the total volume range for better end-to-end SNR.  Remember, whatever range of the volume you can't use (gain too high) is essentially wasted dynamic range.  I've seen systems where the usable volume range only goes to 9 o'clock!  Amplifier SNR above 110dB (our amps are closer to 120dB) really helps with high efficiency speakers.  DACs are the same way, and the chain is only as strong as the weakest link.  This is why we make 130dB+ DACs.  This also facilitates digital volume control without significant resolution loss at low volumes, and why 24-bit data to the DAC is essential for digital volume.  If you hear hiss when you hit pause, there's a noise problem.