Higher Sensitivity/Efficiency vs SQ

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When we judge, what can we look at to see a trend that higher sens/efficiency results in higher SQ? Would one driver have a better impulse than the other due to these factors alone. Decreasing excursion makes sense...Sensitivity doesn't do this, so for me, I'm not concrete on my theories... I theorize that lower signal equates to less heat....sensitivity also relates to enclosure performance....driver sensitivity/efficiency and enclosure sensitivity/efficiency are not created equal. I think this is not highlighted enough.

For me, I guess it sorta comes down to, can you have a really efficient, low sensitivity woofer and how would it sound compared to another woofer with the same efficiency but much lower sensitivity?

I'm interested in seeing the objective side of this debate of low sens vs high sens as well as keeping efficiency in perspective. It also seems that since its possible to translate the acoustical mechanical into the electro mechanical that the math would reflect how these figures relate to distortion...I'm a good designer/philosopher.... not so much a mathematician lol help meeee

:grouphug:
 
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Fs sets the point for efficiency; sensitivity is a matter of impedance Z and also is determined by measuring SPL on axys at 1 meter, consequently the bigger the cone area, the bigger the SPL.
Cone mass sets the sensitivity, either.
None of these are requirements for SQ.
There's a system going on, starting from pick-up and arriving at your ears.
A sound in the room bounces many times on the walls and on any reflective object before dying...
 
Efficiency and sensitivity is the same. So no, you can have a efficient woofer with low sensitivity. I don't know much about the directly objective side of the matter. But from what I've gathered, it's not a direct bond between sensitivity and Sq. The thing is, what makes a driver sensitivitie will change more than just the sensitivity. And therefore it might be other parameters that affects the Sq. You get very good and very bad drivers in all efficiency ranges. Something to think about is how the amplifier reacts to different sensitivities. A weak amp with a small capacitor bank will almost always sound less dynamic on inefficient low impedance speakers.
 
A guy on Extreme posted this
The problem is that you can't just put an enormous motor on a small midwoofer because Le goes through the roof, ruining treble performance and the driver becomes over damped ruining bass performance

Sensitivity = BL*Sd/Mms

Assuming the area of the cone (Sd) and strength of the motor (Bl) can't be changed there is only one option for increasing sensitivity; reducing moving mass (Mms)

This results in lower Le(i) distortion by reducing the magnetic flux required to produce a given output level. However, cone breakup usually becomes harsher and Fs is increased leading to poorer bass extension.

If you aren't using a driver in it's inductive region (~3kHz+ for a good 6.5" midwoofer), then you don't realize any benefit from reducing Le distortion.

Generally you will find that designing for lower xmax is a better strategy for distortion reduction than only designing for higher sensitivity. Placing a resistive attenuator between an amp and a driver is also an effective way of reducing distortion at the expense of sensitivity, because it mimicks a current drive rather than voltage drive.
 
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I thought we all worshipped the holy Impulse and step response?

Allen - if we take sensitivity ratings in free air and then another with enclosure...the difference would equate to the sensitivity added by the enclosure. I imagine some how efficiency can be measured the same way.

I sought to differentiate efficiency from sensitivity because people like to say one or the other is responsible for certain aspects of increasing SQ, but sensitivity seems to be brought up when potentially dynamic headroom may be the culprit.

MrGecco - There are objective ways to look at SQ, IR reproduction is one, its not the final word but a light in the darkness at least, group delay matters, delay, matters, distortion, all the normal aspects we criticize... If I had to use a blanket statement that couldn't be denied, I'd say that the degree of distortion equates to SQ....Distortion being how many degrees different from the signal being supplied in all ways measure-able.



The argument that some make for high Sensitivity is this idea that these types of systems do not compress the signal (level distortion) as much as a low sensitivity driver/system would...the idea that the "sensitivity" brings out "micro details" that were "compressed away".... if it were that simple, it should show in measurements or in the math....is it really the sensitivity or the fact you are using a horn in most of these "high sensitivity" systems or large sd woofers and the lowered excursion efficiency giving the motor much more control.....

In the thread that inspired me to start this one, the high sens advocator talked about how this speaker here
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was low efficiency crap. So I have no vendetta, I already am "team horn load" but I need to see why this fancy looking speaker sucks because having low sensitivity drivers....Usually horns are tied in with high sens advocates, but are the benefits (sonically) really tied to sensitivity or is sensitivity tied to closely to efficiency that its almost the same thing? Otherwise directivity and lowered excursion is the fuel.....so what happens with matched directivity and excursion...high sens vs low sens....some how it does work out because you cant have one without the other (sens vs efficiency) is what I gather via

The problem is that you can't just put an enormous motor on a small midwoofer because Le goes through the roof, ruining treble performance and the driver becomes over damped ruining bass performance

I have no idea ... but I believe you. I should say, how does woofer size cause le to go through the roof?

I would also guess that having a big/powerful motor on a light woofer, if pulled off, proves my point? maybe? I mean compression driver is exactly that (without horn?)...Atc sm75-150s as well?
 

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The argument that some make for high Sensitivity is this idea that these types of systems do not compress the signal (level distortion) as much as a low sensitivity driver/system would...the idea that the "sensitivity" brings out "micro details" that were "compressed away".... if it were that simple, it should show in measurements or in the math....is it really the sensitivity or the fact you are using a horn in most of these "high sensitivity" systems or large sd woofers and the lowered excursion efficiency giving the motor much more control.....
Compression implies non-linearity and suggests it is large. A large non-linearity occurs when a speaker is driven beyond its output capability. High sensitivity systems tend to have higher output capabilities, making it less likely that the speaker compresses the signal.

.. but I think many people do not mean 'compression' when they use this term, as it also seems to be used when the speaker is not playing near its output capability limits. Then we must find something else.
 
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I have thought long about this...I have come to a conclusion that the reason why people associate this dynamic compression or lack of dynamic contrast with lower sensitivity systems, is because the transients don't survive as well in the indirect field...and in the direct energy field, transients stand a much better chance to true representation....so literally this direct to indirect energy ratio...ie the polar...is the culprit. Hf A larger woofer can't help but lower excursion and if possible its resolution will increase because of that. I also imagine that there is a certain norm for the type of FR coloration of reflections one may experience in a typical American finished basement (Faux wood till walls or painted drywall, carpet on top of concrete, acoustic tiling ceiling...increasing the direct energy is going to decrease the colorations from surface reflections. The more stage you give to indirect energy, the more presence of two transient peaks (direct and reflected(indirect)), where there was one to begin with....its like turning up the gain one transient and the gain down on the other transient...not sure how this would cause compression on the signal...I think that
A large non-linearity occurs when a speaker is driven beyond its output capability
this is a good answer, and speaks to dynamic potential of the system...I just grasped wtf a non linearity is lol...I knew, but now I can visualize it. If this type of mechanical limitation non linearity is the culprit then one would just turn down the volume lol....maybe decrease listening distance....and SQ would be restored...but the efficiency thing again...so even at low volume a 15" is going to "dominate" a 4" woofer in a logical comparison? It would seem that excursion would be so low for both that it wouldn't be a factor any more.......but then again the polar comes to play and the 15" is going to be more directional....ok I think I got it.

Sealed 15" woofer vs a 4" midwoofer with a 15" diameter horn/waveguide ( I don't know how to make tuning fair for comparison, maybe tune it to the fs of the sealed system?)......now what?


ps - so minimum phase eq has non linear distortions....resulting in group delay. Am I in the matrix? Linear distortion is a thing to right?
 
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MrGecco - There are objective ways to look at SQ, IR reproduction is one, its not the final word but a light in the darkness at least, group delay matters, delay, matters, distortion, all the normal aspects we criticize... If I had to use a blanket statement that couldn't be denied, I'd say that the degree of distortion equates to SQ....Distortion being how many degrees different from the signal being supplied in all ways measure-able.

Depends on the definition of Sq. Sq and distortion are two different things (in my opinion). Sq is how good something sounds. Ruler flat speakers can sound horrible even though Fr is perfect. There is a reason why people love tube amps even though they measure horribly. Speaker always have some distortion, differing on places in the frequency range and volume. It just depends how it's presented.

Distortion is the actual measurements. But that, often tells you little about if it's going to sound pleasing or not.

Might be that Sq is about distortion and not subjective (or collective subjective) interpretation. But when I see the word used, it often doesn't refer to distortion directly.
 
Its an idea that I came up with to end the arguing, and is essentially in word form, describing the deviation away from the perfect impulse...if that were ever the goal.

Subjective sq is another topic in itself. Even the subjective can be measured objectively...or at least we try lol.
 
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When we judge, what can we look at to see a trend that higher sens/efficiency results in higher SQ? Would one driver have a better impulse than the other due to these factors alone.

For me, I guess it sorta comes down to, can you have a really efficient, low sensitivity woofer and how would it sound compared to another woofer with the same efficiency but much lower sensitivity?

Sensitivity and efficiency are tied together by some simple math; you can't increase one without increasing the other. Efficiency and sensitivity conversion - loudspeaker percent and dB per watt and meter loudspeaker efficiency versus sensitivity vs speaker sensitivity 1 watt = 2,83 volt box chart - sengpielaudio Sengpiel Berlin

At a low signal level, ie 1watt, 2.83v, etc, sensitivity/efficiency has nothing to do with the shape of an impulse or step response.

As has been said so often, impulse and step are a function of frequency response. No more, no less..... where frequency response includes both magnitude and phase.

At high signal levels, sensitivity/efficiency may decrease due to compression, excursion limitations & nonlinearities, etc.
(I guess sensitivity could actually increase a little from out of control THD Lol)

Anyway, my take on why high sensitivity/efficiency is good for SQ, is that it simply ensures there is sufficient SPL for a speaker to play at realistically loud levels, without any lack of any dynamic headroom.
 
At a low signal level, ie 1watt, 2.83v, etc, sensitivity/efficiency has nothing to do with the shape of an impulse or step response.
_ I contest this...lol I have no basis to do so, but...my gut tells me that it has to effect the impulse because in this minimum phase equation everything touches everything else....you can't change something in the chain, without changing the impulse..

As has been said so often, impulse and step are a function of frequency response. No more, no less..... where frequency response includes both magnitude and phase.
_ I thought that the impulse includes FR (you can derive the FR from the impulse)...thus it includes phase and magnitude...er no?
 
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Maybe this will help...https://www.rationalacoustics.com/download/Smaart-v8-User-Guide.pdf

Don't let the size of the manual scare you.
Ch1: Fundamental Concepts and Terminology is all we need for this discussion.

When the light goes off that flat frequency response together with flat zero degree phase response = a perfect impulse response (aka a dirac pulse) = a perfect step response = perfect square wave response......

well, you're gonna be amazed how much easier all this stuff gets...
and how that sensitivity/efficiency doesn't have anything to do with it :)
 
I do get it somewhat...and it is all a minimum phase relationship is what I recall someone telling me.

At high signal levels, sensitivity/efficiency may decrease due to compression, excursion limitations & nonlinearities, etc.
(I guess sensitivity could actually increase a little from out of control THD Lol)

So we just have to add level to the equation and repeat...right?

At a low signal level, ie 1watt, 2.83v, etc, sensitivity/efficiency has nothing to do with the shape of an impulse or step response.

I think I am heading in the right direction by choosing the impulse and step response....So with these two representatives of the high sensitivity/efficiency and low sensitivity/efficiency...We need to change 1watt to something else....like 100watts (random number) and now the Impulse shape changes...

If I could provide you a graph it would show the Impulse/step response at each interval, 1watt all the way to max desired test wattage...this graph will expose what happens when the transient starts losing its original benchmark shape of 1watt. Smoking what I'm putting down?

Eureka! so sensitivity/efficiency does indeed effect impulse/step response...its dependent on the level you measure it at.
 
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So we just have to add level to the equation and repeat...right?




If I could provide you a graph it would show the Impulse/step response at each interval, 1watt all the way to max desired test wattage...this graph will expose what happens when the transient starts losing its original benchmark shape of 1watt. Smoking what I'm putting down?

Eureka! so sensitivity/efficiency does indeed effect impulse/step response...its dependent on the level you measure it at.

I understand what you're putting down...I'm just not gonna smoke any of it :D

Camplo, you can make things as hard, as circular in their logic as you want.


Efficiency is derived from sensitivity. Sensitivity is derived from frequency response at a traditional 1 watt into the nominal impedance drive level.
Sensitivity/efficiency are nothing more than very crudely derived numbers from frequency response. They are "put you in the ball park" specs only.

No one will ever care, or look at impulse or step responses, as drive levels increase, to assess changes in sensitivity/efficiency.
What they will look at, is how frequency response changes with increasing drive levels, once over a certain drive level.
Check out M-Noise for a measurement technique to determine maximum linear SPL.

Impulse and step will look unchanged until that maximum linear SPL is hit.

Then those plots will start to look more sucky....
but who in their right mind would look to impulse and step responses to try to figure out where frequency response is sagging with increased drive levels....
you'd look straight to the sagging frequency response !!

That's why I say it's all about SPL and headroom, throughout the spectrum, and sensitivity/efficiency are just byproduct addon measurements.

Also, If you're not familiar with data-bass excellent high drive level measurements dB v2, go check out how Ricci measures.
 
Then those plots will start to look more sucky....
but who in their right mind would look to impulse and step responses to try to figure out where frequency response is sagging with increased drive levels....
you'd look straight to the sagging frequency response !!

I probably would lol, I'll measure anything lol

dB v2

We should know the short and long term output compression data of all systems. At all times...
 
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