Theoretical question - differences between speaker systems

[toddalin]

Or "is"?

Sorry... just a throwback to the good ol' late 90s.

When it comes to speakers sounding identical, my definition for that would be that, if I were blindfolded, and someone were doing an AB test, I would not be able to hear any difference at all between the two speakers' playback. I would not be able to distinguish between Speaker A and Speaker B.

Even then, you would need to play all types of music and test tones to reveal differences. A limited sampling may not reveal differences that a broader sampling might.

 

[cwall99]

Even then, you would need to play all types of music and test tones to reveal differences. A limited sampling may not reveal differences that a broader sampling might.

True, but then, if you stop and think about it, you'd never be able to make this a definite assertion until you played every recording in every format. And while I'd certainly appreciate listening to music this way, especially if we're talking about a nice system hooked up to two different, but very similar sounding, types of speakers....

Now, if I could find someone to pay me a comfortable salary to do this, then I'd say, "Yeah, let's bring it on," but, now it may be different in your neck of the woods, I don't see too many job postings for speaker auditioners (or whatever someone's job title might be if they did this).

I'm just funnin' with ya todd. Of course you're correct, but I'll stick with my definition of what the definition of "identical" means in this context.

 

[Zilch]

As it seems evident that I don't have a remote clue in these matters, I'll refrain from commenting in further discussions.

Bah.

Don't be wussin' out on us in exploring the fun stuff here.

It ain't about who's right or wrong or to what degree, nor is anybody's esteem on the line.... :nono:

 

[GordonW]

True transient response happens strictly in the time domain and can be very easily determined by the frequency response and vice-versa (Fourier transform).

But the complication happens because frequency and phase response are power dependent (i.e, distortion/compression, etc). So stuff like "dynamics" is simply describing an "end effect" from the fundamental characteristics of frequency, phase, and distortion performance.

Fourier transformation uses the assumption of LINEAR, reversible systems.

Systems that distort (in either the area of harmonic generation or time/energy storage effects) will NOT be definitively identified as such, by a simple non-gated frequency response measurement, as many speakers are specified (i.e, a pink noise in -> response plot out).

You have to know WHEN the sound is being produced, and what harmonics are being produced by each fundamental frequency, in order to quantify what the speaker actually sounds like. This is where comprehensive distortion analysis becomes important. What if the speaker has a natural dip at 1KHz, but a bad 333 1/3 Hz, third-order (third harmonic of 333 1/3 Hz is 1KHz) distortion peak? In pink noise, the distortion added to the signal can MASK the natural response dip. However, in gated measurement, these anomalies can be separated and identified.

In another case... you have a cabinet/driver system with a standing wave resonance... which causes a peak at a certain frequency. But, the designer, to "mask" this, designs in an electrical "dip" (notch filter, etc) at that frequency. In a steady-state FR measurement, the standing wave will "build up energy" at the resonant frequency, and the electrical dip will be "filled in" to show "flat" response. However, in a gated, short-duration measurement (pulse tones, fast sweeps, or variations), the dip in INITIAL response will be apparent. And, in a decay measurement, the "energy storage" of the standing wave will be apparent, as a "lagging signature" in the waterfall plot...

The moral is: You have to KNOW how the supposed "identical frequency response" was calculated. If it's not done with some insight into the time domain and isolating frequency from frequency in the results, you can get fooled badly...

Regards,
Gordon.

 

[ron-c]

Identical frequency response as commonly measured, in an anechoic chamber, does not mean two different speakers will sound the same. Once you place the two speakers in a live room they will differ in sound since they will react to any given room in unique ways.

Thanks,
Ron-C

 

[Negotiableterms]

... nor is anybody's esteem on the line.... :nono:

This implies that each of us has some esteem to begin with. In any technical area, I hereby stipulate that I know just enough to be dangerous.

BTW, I think that Gordon might just have said, properly, what I was trying to say, vaguely... and I'm not even sure I understand enough to say that!

 

[JonL]

Gordon, thanks for that post. That was a very clear explanation of how things can be different from how they appear. Or an example of how to lie with statistics. Which, to clarify, in no way means that I am anti-measurement or anti-statistics. I am wholly in favor of measurements and statistics that are properly performed and applied, and that often requires a level of sophistication beyond the obvious. Thanks again!

 

[ken kantor]

It's nice to be needed.... but I think you are doing great! My 20cents:

Short Answer:

Yes, they will sound different, based on any one or two frequency response measurements.

Medium Answer:

No, they will sound identical. If one could get a reasonable number of carefully chosen frequency response measurements to match, two different speakers can sound arbitrarily close to one another. (The generally impossible, part is to get both direct and room responses matched at the same time.)

Long Answer:

FR is a simple and helpful way to think about components that work in the electrical domain: amps, CD players, etc. Sure, there are a few other factors that influence hearing besides frequency response. But, it is very well established that FR dominates sound perception, by a large margin. Besides, if you can get the FR to truly match, the other things will line up as a matter of course.

Unfortunately, the whole idea of a "frequency response" is not well-defined when it comes to speakers. A speaker has a response that varies not only as a function of frequency, it also varies according to direction and time. When you add this to a complicated room response... ouch! So, really, any frequency response measurement taken of a speaker is only valid for a unique point in space, in a given room, integrated over an arbitrary time window, with a given directional weighting, etc. No doubt, one can infer much about the sound of a speaker by studying even simple measurements. But, there is a serious limit to how much any given measurement set tells you. I suspect this is one reason why speakers haven't gotten all that much better than they were decades ago: we know how to make measurements, but our understanding of them is rather primitive. All attempts to define an "ideal" speaker fall apart under scrutiny. So, we make them smaller, cheaper, higher powered, etc. Getting them to be more accurate is elusive.

But that's what makes speaker design so much fun...

-k

While I am clearly a proponent of objectivism in these forums, and frequently cite and argue extreme positions on such matters, in the more practical context of OP's question:

The answer is "No, there is more, some of which we have only just begun to explore and understand."

[Where is Ken Kantor when I need him...? :tongue: ]

 

[GordonW]

I will say this-

If you had two speakers that had identical on- and off-axis waterfall plots over all angles, and identical distortion signatures (same distortion components at the same magnitudes, at every frequency), it'd be very hard for them to sound much different. In theory, that should take care of most time-dependent, radiation-pattern-dependent, and distortion-related issues.

The rub is- to ever get to differing component sets to actually DO that!

And the idea of doing a comprehensive distortion spectra analysis (each harmonic analysis out to the end of audibility- i.e, every harmonic at or below 20KHz for every frequency) over that kind of frequency resolution (even 1/12th octave, which, to my estimation, would be about the minimum you could get by with), from 10Hz -20KHz... THAT would take some SERIOUS computing power, and time, even now...

Regards,
Gordon.

 

[TerryO]

I'd like to thank both Ken and Nikko75 for taking their time to post their insightful and carefully considered replies to the question at hand. What had seemed self-evident to me, appears to have been a rather elusive matter after all.

Best Regards,
TerryO

 

[jwalker]

jwalker while I don't have the expertise you do isn't there an absolute db limitation going on in smaller less efficent speakers as well? For example when I had my Klipsch Hersies they would occasionally startle me with just how loud an occasional transient peak was, which I never hear in such a dramatic way on my NHT Super Ones. If you hypothetically equalized the frequency response of say a big horn loaded speaker and a small bookshelf they might sound very similar on softer material on axis but I think a difference in volume will be heard on transient peaks that will suddenly make them sound very different.

Coil driven speakers are displacement limited. Some motors have "longer" magnetic gaps (longer "throw") which allow the cone to move farther with the same efficiency. Once the coil moves past the linear portion of the gap, the output will "compress" with resulting loss of output for the same input power (lower power added efficiency). You'll also introduce distortion.

The way you can test your "transient peak" effect is to measure frequency response by stepping to higher powers, say 100 watts to 1 watt. You will notice that the frequency response will change vs. input power. You'll also start seeing second order effects from the heating of the coil which WILL affect the response.

 

[Zilch]

Pop Quiz:

1) Who are these guys?

2) Would we guess they discussed this very topic?

[3) Is that a Sprite, Simi? ]

 

[RayW]

Col. Sanders?

edit: Note, that's a joke. I know who they are, but that guy on the left looks a bit shifty to me.

 

[klama2006]

I’m a speaker aficionado / hoarder.

The more speakers I listen too, the more I see how similar they all sound. Allot of speakers could sound really good when properly placed. There will always be the ones that stand out from the rest, when given your own personnel environment.

But the trade off usually comes at a cost. Most of the time, it’s just a lateral move in trade-offs. But it’s a maneuver that moves you closer to what you yourself wants’ to hear.

 

[barredowl]

Ken thanks again for posting here.

As a brief OT may I ask what you are working on these days? NHT is now under different ownership, correct?

 

[bshorey]

When one speaker is "better" than another, or more detailed, or has "more air", or "more presence", or even if an instrument section appears to be in a slightly different space than when heard with another speaker...are these observations solely a function of the speaker's frequency response?

In other words, if two speakers have an identical frequency response, and are placed in the same spot in the same room, will they sound identical?

Unlikely, imo. Frequency response is simply a measurement of the range of frequencies over which a speaker can produce sound. It doesn't take into account things like dispersion, which can greatly affect how a speaker sounds in a given placement. In addition, while you may place boundaries on the level of variation across the frequency range (for example, 30 hz - 20 khx, +/- 3db), you don't necessarily know where in the range you're producing higher or lower volumes. An acoustic suspension enclosure and a bass reflex enclosure may share the same frequency response, but would most likely have different volume curve across the bass spectrum.

Is it worth mentioning the differences between speaker types, for example traditional, electrostatic, etc? Again, possible to find types with the same frequency response, but placed at the same position in a room they will not sound the same.

My .02,

bs

 

[bshorey]

When one speaker is "better" than another, or more detailed, or has "more air", or "more presence", or even if an instrument section appears to be in a slightly different space than when heard with another speaker...are these observations solely a function of the speaker's frequency response?

In other words, if two speakers have an identical frequency response, and are placed in the same spot in the same room, will they sound identical?

Unlikely, imo. Frequency response is simply a measurement of the range of frequencies over which a speaker can produce sound. It doesn't take into account things like dispersion, which can greatly affect how a speaker sounds in a given placement. In addition, while you may place boundaries on the level of variation across the frequency range (for example, 30 hz - 20 khx, +/- 3db), you don't necessarily know where in the range you're producing higher or lower volumes. An acoustic suspension enclosure and a bass reflex enclosure may share the same frequency response, but would most likely have different volume curve across the bass spectrum.

Is it worth mentioning the differences between speaker types, for example traditional, electrostatic, etc? Again, possible to find types with the same frequency response, but placed at the same position in a room they will not sound the same.

My .02,

bs

 

[TerryO]

Unlikely, imo. Frequency response is simply a measurement of the range of frequencies over which a speaker can produce sound. It doesn't take into account things like dispersion, which can greatly affect how a speaker sounds in a given placement. In addition, while you may place boundaries on the level of variation across the frequency range (for example, 30 hz - 20 khx, +/- 3db), you don't necessarily know where in the range you're producing higher or lower volumes. An acoustic suspension enclosure and a bass reflex enclosure may share the same frequency response, but would most likely have different volume curve across the bass spectrum.

Is it worth mentioning the differences between speaker types, for example traditional, electrostatic, etc? Again, possible to find types with the same frequency response, but placed at the same position in a room they will not sound the same.

My .02,

bs

I think that if you review the previous posts in this thread that you may change your mind (or opinion) on what is the purpose of frequency response measurements, and if done with care, what they can tell you about the sound that will be produced from the speaker in question. They can, and do, provide a great deal more information than you're aware of, based on your post.

Your example of the Bass Reflex and Acoustic Suspension enclosures sharing the same frequency response and yet would have different "volume curves" across the bass spectrum is just plain wrong. If the frequency response is the same, then both will share the same "volume curve." In fact, in very simple terms, that's what a frequency response is, the "volume curve" of the speaker across the entire designated frequency span (often shown as 20Hz to 20kHz, but can go lower and higher).

Your last statement brings up some of the elements of the disagreement present in this thread. Keeping in mind that the original question was of an absolutely theoretical nature, that is, if two different speakers, that had an "identical" frequency response were placed in the identical spot in the same room, would they sound identical? I assumed that by being "identical" that would mean the frequency response taken on every axis. If this was the case, I suggested they would indeed sound the same. This ignores the fact that the probability of ever finding two different speakers with the "identical" frequency response is close to zero. The use of only on-axis response curves is, IMHO, of limited utility in determining what a speaker may sound like in a real world environment.

In your last paragraph you mention that electrostatic speakers (panel speakers?) and "traditional" (horns?) can have the same frequency response and yet, would sound different even if placed in the same position in a room.
The fact is, that if frequency response measurements were taken. not only on-axis, but also off-axis horizontally and vertically, you would certainly see major differences. If, by some change in the nature of Physics, they produced "identical" frequency responses using the protocol mentioned, then I believe they would certainly sound identical if placed in the same spot, in the same room.

FWIW: I certainly don't expect to see anything of the sort in my lifetime, so I'm not holding my breath.

Best Regards,
TerryO

 

[ron-c]

Total radiated sound by a speaker in a space is referred to as Power Response. Frequency response is measured at one point and not terribly standardized other than one meter back from the front of the speaker.


Thanks,
Ron-C

 

[TerryO]

Total radiated sound by a speaker in a space is referred to as Power Response. Frequency response is measured at one point and not terribly standardized other than one meter back from the front of the speaker.


Thanks,
Ron-C

You're certainly correct about the terminology, and how do you think Power Response is measured?

Best Regards,
TerryO