audio2design
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Not really. That's a line array only over a narrow frequency range.
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Do high-efficiency speakers really have better 'dynamics'?
- Thread starter Gorgonzola
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Not really. That's a line array only over a narrow frequency range.
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I have, look for my posts that mention Modulation Transfer Function, for a loudspeaker, it's essentially the degree the sound can start and stop -or- the difference (dynamics) between the on and off periods of the modulation.
What is more dynamic something that has a large or small difference between when on at 100% or off 100%?
The MTF (at 7 frequencies in the voice spectrum) is what is used to make a language independent prediction of voice intelligibility (STIpa) in the industry i design in.
Tom Danley
Danley Sound Labs
Hi Tom, thank you (and from all of us i'm sure) for your continuing comments.
And Hi forum,
I had a brief chance to play with STIpa outdoors a few weeks ago, trying to learn about the role of MTF in perhaps explaining the new level of perceived clarity in my DIY synergies.
Mic distance was about 3m away, off a fairly open deck. Wow, i didn't know know the STI sweeps had to be at least 1.6 seconds long, and timing wasn't right to subject the neighborhood to too much of it. So brief is all i got.
Anyway, here is what Smaart calculated.....which made me very happy...although admittedly i don't really even know what the good score means or how to continue testing with STIpa on a single speaker, other than turn up the volume and see how long it holds up.
And REW gave this for THD, (but again at only fairly low SPL).
I guess the next test that seems to make sense, will be to STIpa measure two different DIY builds at the same time.
Builds that have the same freq, phase, and distortion response; and that i think i hear a difference in their clarity.
I'd love to get a repeatable difference of some kind that correlates with my ears.
And Hi forum,
I had a brief chance to play with STIpa outdoors a few weeks ago, trying to learn about the role of MTF in perhaps explaining the new level of perceived clarity in my DIY synergies.
Mic distance was about 3m away, off a fairly open deck. Wow, i didn't know know the STI sweeps had to be at least 1.6 seconds long, and timing wasn't right to subject the neighborhood to too much of it. So brief is all i got.
Anyway, here is what Smaart calculated.....which made me very happy...although admittedly i don't really even know what the good score means or how to continue testing with STIpa on a single speaker, other than turn up the volume and see how long it holds up.
And REW gave this for THD, (but again at only fairly low SPL).
I guess the next test that seems to make sense, will be to STIpa measure two different DIY builds at the same time.
Builds that have the same freq, phase, and distortion response; and that i think i hear a difference in their clarity.
I'd love to get a repeatable difference of some kind that correlates with my ears.
tuga
Major Contributor
It also happens with multi-way horns, which produce constant narrow dispersion over the most of the audio spectrum (I would expect the Trio model to have negligible flare in the crossover regions).
https://www.fidelity-online.de/avantgarde-acoustic-uno-xd-messungen/
Avantgarde Uno Nano, lateral response family at 50", normalized to response on optimal axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.
https://www.stereophile.com/content/avantgarde-acoustic-uno-nano-loudspeaker-measurements
carewser
Senior Member
unless they have incredibly low power handling, yes
kyle_neuron
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You need velocity and pressure, at coincident points, to calculate the acoustic impedance. It then helps to normalise that complex value per frequency by the specific impedance of the medium (air) and the radiating surface area to allow for easier comparisons.
There's a 'magic wand' for this. It's called a Microflown, and costs £10k+
The common method is to mount the object on a plane wave tube, and measure pressure at multiple points along the inner side walls before carrying out transfer function measurements between the data. An (ideal) transducer is used to drive the tube. There is a cool toy that can be bolted to speaker boxes, using a graphene driver and built in mics to measure the rear of the sealed driving enclosure, and the opening to the decide under test, but it's also expensive.
This works because you can deduce the particle velocity between two measurements of complex values pressure across a virtual plane, with some accuracy, if the mics are perfectly matched and there’s otherwise equivalent radiation conditions in all coplanar directions.
The easiest way to do this in modern times is with an Ambisonic or A-format mic. It isn’t amazingly accurate especially at all frequencies, but you can get a good picture with relative ease using say a Tetramic and four equal / matched mic preamps. That only gives the radiation impedance at that point though; you’d need to do this across the surface of a horn or driver to be sure.
The other option for direct radiators is to mount an accelerometer and mic capsule on the cone, then apply some integral calculus to determine a mean value for the radiator. Or use a laser vibrometer, like the Klippel attachment.
If you have the acoustic impedance at the throat, port, radiator, and listening position etc then you can determine the transfer impedance, including the room air load itself. That applies even in an anechoic room.
This is pretty far into 'lab work' though, not really the sort of thing you'd do for most end user cases. A good design will have this stuff considered way ahead of that, even if only using the 'simple' analytical cases for a rigid piston in infinite baffle, or flanged tube, etc.
I can recommend some acoustics texts if you're curious but be warned, it is heavy stuff.
kyle_neuron
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Remember a good rule of thumb is that each time you double the mutually coupled radiating area (a factor of 1.4) then you also shift the highest frequency of coupling down by the inverse factor (multiply by 0.7) so there are diminishing returns doing this.
From a good summary of sound radiation by Eargle for the AES:
AES E-Library » Historical Perspectives and Technology Overview of Loudspeakers for Sound Reinforcement
[feature] Horns and direct-radiating systems have provided the basis for sound reinforcement for more than a century. Both technologies have benefited from engineering and manufacturing improvements as well as demands for pushing the performance envelope. Trends of fashion have often intersected...
It's one reason why a big array of direct-radiating subwoofers ends up sounding 'deep' at the expense of a clean impulsive kick drum - there's a significant tonal shift from the reliance on mutual coupling.
What’s real fun is that recent research shows this same effect also happens with a dense crowd in front of subs at a concert (outdoors) - the bodies have their own acoustic impedance which is imparted onto the subwoofer output, so it can become quite pronounced.
No free lunches in audio
Sorry for the double post!
At this point I think a short intermission is in order. This thread started with a question:
Do high-efficiency speakers really have better 'dynamics'?
A very experienced audiophile on another forum recently asserted that high-efficiency speakers were inherently more dynamic than other types. By high-efficiency I believe he meant >92 dB sensitivity; by "dynamic" I believe he meant more brilliant response to transient signals. Do hi-eff...
www.audiosciencereview.com
The question seems to be answered with "yes" implicitly. Sufficiently many people jumped on the bandwagon to optimize or better to say totalize the idea of a high efficiency speaker, so searching out for more, total dynamics as to optimize their daily stereo experience at home.
Or, one might see this as an effort to prepare for an actual, critical listening test. The other side of the comparison is missing, though. What would be the least efficient speaker? One might even argue, whether the high efficiency side is actually of high efficiency, or is only capable of big output due to big appetite for amp-power.
With one or the other interpretation, where is this going to, with all its enthusiasm? Thanks a lot!
kyle_neuron
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My personal experience fully agrees with your summary. The short answer is 'yes', the longer answer perhaps has some caveats and of course, interesting conflicts of opinion or theory as to the 'why'. That's the fun part though, right?At this point I think a short intermission is in order. This thread started with a question:
Do high-efficiency speakers really have better 'dynamics'?
A very experienced audiophile on another forum recently asserted that high-efficiency speakers were inherently more dynamic than other types. By high-efficiency I believe he meant >92 dB sensitivity; by "dynamic" I believe he meant more brilliant response to transient signals. Do hi-eff...
The question seems to be answered with "yes" implicitly. Sufficiently many people jumped on the bandwagon to optimize or better to say totalize the idea of a high efficiency speaker, so searching out for more, total dynamics as to optimize their daily stereo experience at home.
Or, one might see this as an effort to prepare for an actual, critical listening test. The other side of the comparison is missing, though. What would be the least efficient speaker? One might even argue, whether the high efficiency side is actually of high efficiency, or is only capable of big output due to big appetite for amp-power.
With one or the other interpretation, where is this going to, with all its enthusiasm? Thanks a lot!
Like so many things, this is something I really wanted to test for a dissertation topic. I was explicitly interested in subwoofers, but mains would have been of interest too. Unfortunately, controlled listening tests are hard to run 'properly' (as in good, repeatable, trustworthy science) when you aren't in a pandemic let alone in the past year
This is one particular test where you kind of need the physical boxes in place, and can't really use recorded impulse responses or samples on headphones with the same level of effect, in my opinion. At the very least, you'd want to do that typical method and compare to the subjective results from a double-blind, randomised order test using the same subjects with the real thing.
Sadly I no longer have free access to a hemi-anechoic chamber, which would have allowed for control of the 'directivity' aspect that's also been a part of the discussion. I'm also on the other side of a big pond to the majority of people here, too!
However, I'd be happy to offer help & advice on doing it in the 'accepted science' format, both test design / data gathering and processing / reporting if someone was perhaps up for arranging an ASR 'meetup' somewhere in the future, with this (and perhaps other tests) as part of the experience? Sadly the 'boring stuff' is super important if you want the data to be of any real worth, and to hold up under scrutinity - which it will be subjected to a lot of. Things like ensuring the speakers under test are level matched to within a fraction of a decibel, even equalised to the same axial magnitude response within a given frequency range like 200 Hz - 3 kHz, and all at equal distances to boundaries. Stuff like where the listener will stand, how you'll make sure they get (and stay) in that general position, how the switching is done - perhaps asking them to rotate to look at the new speaker location, using an indicator LED? When and how do you gather their feedback - after each sample, or all at once at the end? How does that affect the data, and how do you weight accordingly based on that, listener 'experience', age, hearing condition, etc etc etc...
Depending on dates, perhaps I could even look at tying in a visit to some Stateside pals at the same time to attend and help run the thing... have mics, will travel
Count me one. From your avatar I know what I am about to get, I am ready for hell!!!!!!
Yo, I still think someone who issues bold claims should find an own way to prove them. Vice versa I don't think science should follow down "experienced stereo users" into every rabbit hole. Such all too friendly move has proven to be unrewarding to the max.
But, please go ahead. Sorry for interferring.
kyle_neuron
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Sorry, it seems you may have read my comment the wrong way, I was agreeing with you! Also merely trying to expand on a way that you (plural, aka the community) could test this experimentally.
The problem with experiments is that when you have lots of variables, that all change between samples, the data isn’t able to produce clear conclusions that are easy to defend against criticism.
Of course, you can always do the test again with less “matching” and see if the results are similar, but if you don’t have a controlled test as a base line it makes life very difficult. Statistics is the horrible part in my experience - but it’s crucial to disprove the null hypothesis. I fell afoul of this on another listening test when there was simply so much data that it took forever to do all the pair-wise comparisons, linear regressions and the like with the relevant corrections or weightings.
There's no reason why a scientifically 'correct' test process can't also be a fun day out, if well planned
Count me one. From your avatar I know what I am about to get, I am ready for hell!!!!!!
Edit: Here we go
First up, this is a good open-access paper reviewing the various methods to measure acoustic impedance - plenty of diagrams and relatively light on equations:
An Overview of Acoustic Impedance Measurement Techniques and Future Prospects
In order to progress in the area of aeroacoustics, experimental measurements are necessary. Not only are they required for engineering applications in acoustics and noise engineering, but also they are necessary for developing models of acoustic phenomenon around us. One measurement of...
www.mdpi.com
The two ISO standards give a bit more insight into plane-wave tube methods:
ISO 10534-1:1996
Acoustics — Determination of sound absorption coefficient and impedance in impedance tubes — Part 1: Method using standing wave ratio
ISO 10534-2:1998
Acoustics — Determination of sound absorption coefficient and impedance in impedance tubes — Part 2: Transfer-function method
For general acoustics knowledge, I'd recommend these as a starter - they're fairly 'plain English' with lots of photos or diagrams. Sadly, there's no getting away from the maths in this stuff, but these books aren't just walls of symbols, I promise!
Acoustics
This definitive textbook provides students with a comprehensive introduction to acoustics. Beginning with the basic physical ideas, Acoustics balances the fundamentals with engineering aspects, applications and electroacoustics, also covering music, speech and the properties of human hearing...
books.google.co.uk
Foundations of Engineering Acoustics - 1st Edition | Elsevier Shop
Purchase Foundations of Engineering Acoustics - 1st Edition. Print Book & E-Book. ISBN 9780122476655, 9780080506838
Science of Sound, The, Pearson New International Edition
If you'd like more of the raw stuff, then these are a few of the classics:
Acoustical engineering. by Harry Ferdinand Olson | Open Library
Acoustical engineering by Harry Ferdinand Olson, unknown edition,
Applied acoustics (Book, 1939) [WorldCat.org]
Get this from a library! Applied acoustics. [Harry F Olson; Frank Massa]
www.worldcat.org
Acoustics: Sound Fields and Transducers
Acoustics: Sound Fields and Transducers is a thoroughly updated version of Leo Beranek's classic 1954 book that retains and expands on the original's ...
www.sciencedirect.com
Room Acoustics
Well established as a classic reference and specialised textbook, since its first publication in 1973, Heinrich Kuttruff’s Room Acoustics combines detailed coverage with a state of art presentation of the theory and practice of sound behaviour in closed spaces.This sixth edition presents several...
Sound Intensity
The advent of instruments capable of measuring sound intensity, which represents the flow of energy in sound fields, has revolutionised audio-frequency acoustical metrology. Since publication of the first edition, two International Standards for the use of sound intensity for sound source power...
For 'general audio' references, you can't go far wrong with these:
Audio Engineering: Know It All, Volume 1 - 1st Edition | Elsevier Shop
Purchase Audio Engineering: Know It All, Volume 1 - 1st Edition. Print Book & E-Book. ISBN 9781856175265, 9780080949642
Loudspeaker Handbook
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Loudspeaker and Headphone Handbook
Written by a team of experts, the Loudspeaker and Headphone Handbook provides a detailed technical reference of all aspects of loudspeakers and headphones: from theory and construction of transducer drive units and enclosures, to such practical matters as construction, applications in rooms...
Audio Metering: Measurements, Standards and Practice
In this comprehensive guide, Brixen takes the reader through the complex and confusing aspects of audio metering, imparting the knowledge and skills needed to utilize optional signal levels and produce high-quality audio. Covering all aspects of this fundamental subject, Audio Metering...
Handbook for Sound Engineers
Handbook for Sound Engineers is the most comprehensive reference available for audio engineers, and is a must read for all who work in audio. With contributions from many of the top professionals in the field, including Glen Ballou on interpretation systems, intercoms, assistive listening, and...
Sound System Engineering
Long considered one of the key books on the well-informed audio engineer’s shelf, Sound System Engineering provides an accurate, complete, and concise tool for all those involved in designing, implementing, and testing sound reinforcement systems. This new fourth edition includes eight new...
It's always good to have some stuff on how/why we hear what we actually do:
https://www.sciencedirect.com/book/9780240521756/acoustics-and-psychoacoustics (I really recommend this one, it's brilliant!)
Hearing
Hearing is a detailed introduction to the perception of sound and its neural basis. Highlights include a special historical review of the...
www.goodreads.com
The Technology of Binaural Listening
And some other 'related' books I recently found useful or enjoyed:
Acoustics - 1st Edition | Elsevier Shop
Purchase Acoustics - 1st Edition. Print Book & E-Book. ISBN 9780122561900, 9780080498553
Spatial Audio
Explores the principles and practical considerations of spatial sound recording and reproduction. Particular emphasis is given to the increasing importance of multichannel surround sound and 3D audio, including binaural approaches, without ignoring conventional stereo. The enhancement of spatial...
The Digital Evolution of Live Music
The concept of ‘live’ has changed as a consequence of mediated culture. Interaction may occur in real time, but not necessarily in shared physical spa...
www.sciencedirect.com
The Science of Sound Recording
The Science of Sound Recording will provide you with more than just an introduction to sound and recording, it will allow you to dive right into some of the technical areas that often appear overwhelming to anyone without an electrical engineering or physics background. The Science of Sound...
Recording Studio Design
Recording Studio Design, Fourth Edition explains the key principles of successful studio design and construction using straightforward language and the use of practical examples appreciated by readers of previous editions. Updated to reflect new industry standards, this fourth edition addresses...
Rock and Pop Venues
Architectural Acoustics Illustrated
Buy Architectural Acoustics Illustrated by Ermann M from RIBA Online Bookshop. ISBN 9781118568491
www.ribabooks.com
Digital Fundamentals, Global Edition
Of course I think everyone here is familiar enough with Toole & Olive's book that I don't need to post it!
That little lot should keep your birthday and Christmas lists full for a while
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O/k, I still don't get it. We've got a bold claim, which to begin with isn't in any way specific. Clarification wasn't supported. Instead one side of the story was worked out, namely the very much most efficient speaker was identified. You and others supported the enthusiastic community in this quest.
So, how to proceed now? Is it agreed that You personally take the effort to set-up and process the test of the original claim of an anonymous experienced audiophile?
I'm just curious and I'm pretty sure I missed a thing or two. If You need somebody to peer review the result, I would say I'm qualified (see me waving my papers ...)
Very interesting! It's easy to intuit that the mutual coupling loses effectiveness as frequency goes up but it's clarifying to see it graphed out. I'm using four 18" woofers in corner horn cabinets stacked to the ceiling with a crossover up at 300Hz. This does go deep for a front loaded horn setup but does not produce a clean impulsive kick drum like I've heard form other systems, which is a disappointment and maybe related to this coupling issue. Recently I put absorption in the mouths of the two outer horns (upper and bottom) to deal with a cancelation that was happening at 75Hz. This had the inadvertent effect of absorbing the upper end output of those outer horns so now only the two middle horns are producing most of the upper end of their passband. With the EQ readjusted I think it sounds a little cleaner and punchier that way.Remember a good rule of thumb is that each time you double the mutually coupled radiating area (a factor of 1.4) then you also shift the highest frequency of coupling down by the inverse factor (multiply by 0.7) so there are diminishing returns doing this.
From a good summary of sound radiation by Eargle for the AES:
View attachment 164606
AES E-Library » Historical Perspectives and Technology Overview of Loudspeakers for Sound Reinforcement
[feature] Horns and direct-radiating systems have provided the basis for sound reinforcement for more than a century. Both technologies have benefited from engineering and manufacturing improvements as well as demands for pushing the performance envelope. Trends of fashion have often intersected...www.aes.org
It's one reason why a big array of direct-radiating subwoofers ends up sounding 'deep' at the expense of a clean impulsive kick drum - there's a significant tonal shift from the reliance on mutual coupling.
What’s real fun is that recent research shows this same effect also happens with a dense crowd in front of subs at a concert (outdoors) - the bodies have their own acoustic impedance which is imparted onto the subwoofer output, so it can become quite pronounced.
No free lunches in audio
Sorry for the double post!
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Do high-efficiency speakers have better dynamics? About 33% of the time, yes. History shows high efficiency usually comes at the cost of a jagged FR. Thus if the destination note of an expressive figure hits at a FR peak, dynamics are literally expanded, by many dB in a typical case. If it hits at a FR trough, then the speaker is a compressor. In the middle, it's the same as any other speaker. Or is that thinking too simplistic?
Richard Berg
Member
How about taking a single speaker that's "known" to be efficient in the desireable way(s), and reducing its efficiency via electronic means? That would remove a ton of variables from the equation.
If we believe that the source of "better dynamics" is the physical coupling of the box-n-drivers to the room's atmospheric pressure, rather than the raw watts-per-dB capability of the box as a whole, then this test should produce a null result. Either way, we'd learn something...
To learn the slightest, You have to define the other end, namely the least effcient speaker. This is all so illogical. Why is my personal experience, that the claim of "more efficient == more dynamic" is not true, overtly dismissed?! Really, I've got specimen ranging from 80dB/Watt up to 100+dB/Watt in comparison. No difference between, nothing to backup the claim.
I state the missing difference, and I like You to acknowledge it. The other "audiophile" is plain wrong. What do You think about it?!
KSTR
Major Contributor
IHMO that doesn't work out.
To reduce efficiency you must do that in the driver proper, you cannot fake it from the outside. But when you do you alter the driver parameters and it's (nonlinear) error mechanisms --> not the same driver.
Personally I do like the perceived more dynamic sound of many high-efficiency drivers but I'm far from convinced this has much to do with effciency itself...
Richard Berg
Member
If you want to propose your own test methodology, go ahead.
Nobody has claimed that any one test will reveal everything there is to know about speaker preferences.
Richard Berg
Member
So you agree with me that my test should produce a null result?
That makes 1 prediction for and 1 against, so far -- good evidence that the test is worth running!
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