-
Welcome to ASR. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
"Inefficient" speakers are "worse" than "efficient" speakers
- Thread starter Luvchampagne
- Start date
That ties in nicely with
Doppler distortion vs IMD?
purifi-audio.com
Which, mind you, is a bit academic since FM-to-AM conversion is very common, courtesy of the resident reflections / multipath propagation introducing frequency response ripple. So you might conceivably encounter cases of level handling in a small, high-excursion (2-way) design being improved by acoustic optimisation.
Anyway, the statement "higher sensitivity -> lower distortion" implicitly assumes all else being equal, which of course it rarely is. Driver designers are, in general, no dummies. When faced with the challenge of trying to build smaller drivers with higher excursion, they will be looking for ways to improve their motor designs for better linearity, up to the point of going all Purifi on them:
Distortion, The Sound That Dare Not Speak Its Name
purifi-audio.com
Chris A
Senior Member
Candidly, I get a bit skeptical of design solutions (and engineering enterprises) which totally ignore really effective design approach alternatives, and further common misconceptions. To wit:
Also, apparently calling flux modulation distortion to be "Force Factor Modulation" seems like a disservice to Klippel's work...but hey, that's just my opinion.
YMMV.
Chris
In horn-loaded (including waveguides) applications, these two distortion types are very different: one is present and the other basically isn't. I would be okay with most of what was said in that article if they didn't try to muddy the water further in this regard.
Also, apparently calling flux modulation distortion to be "Force Factor Modulation" seems like a disservice to Klippel's work...but hey, that's just my opinion.
YMMV.
Chris
[Off topic] I can't tell how glad I am that you pick that up! There is FM to AM conversion. And you can test it at home. Please give it a try.That ties in nicely with
Doppler distortion vs IMD?
Which, mind you, is a bit academic since FM-to-AM conversion is very common, courtesy of the resident reflections / multipath propagation introducing frequency response ripple.
With headphones the effect of diminishing FM is obvious. With speakers the FM will be heard after conversion. It is not so that your speakers are broken, it is that conversion, that makes the difference.
[/Off topic]
Kudos to Purify, that they leave the example on site.
Yes. Directivity is my priority, and high efficiency is a side effect.
A7 "Voice of the Theater" speakers reveal the inverse of Hoffman's Iron Law (btw, Hoffman was Henry Kloss's partner at Advent). If reducing size decreases sensitivity, then increasing size raises it. That's one of the reasons they were large--amps of the day were relatively small. I don't recall the official sensitivity--Google says it's 103-105 dB/W/m--but we used a pair for a country band that could fill a ballroom with deafening sound if they wanted to using a McIntosh amp that may have been 150 WPC.
But the bass reflex cabinet used in the A7 included an exponential horn baffle in front of the woofer, and that projects the sound out front to a greater extent than any home speaker. They would not measure that great, perhaps, in home use simply because of their long-throw horn, though there may be strategies to make them work. But that's not what they were made for.
Rick "different use cases bring different requirements that suggest different tradeoffs" Denney
Probably already said: Sensitivity numbers don't really tell us how loudly a speaker will play. But an inefficient speaker is more likely to run out of headroom than a more efficient speaker at a given desired SPL. If a low-efficient speaker (83 dB) starts to compress from lack of compliance at 100 dB SPL, then the same 27 dB of headroom applied to a 90 dB-sensitivity speaker can go to 107 dB before compressing. That's a big different for those who want to play dynamic music loudly.
But the actual headroom is a matter of design also.
Rick "whose Revel towers are 90-dB sensitive" Denney
But the actual headroom is a matter of design also.
Rick "whose Revel towers are 90-dB sensitive" Denney
Kudos to Purifi for publishing so many technical details on their website. @Lars Risbo
that is not true.if the compliance is the same then the distortion vs SPL is the same too (assuming compliance is the dominant source of distortion).
Looneybomber
Active Member
- Joined
- Sep 23, 2022
- Messages
- 135
- Likes
- 162
Sure. Put an L-pad in front of it. We’re talking loudspeakers here, not drivers. That’s the title of this thread. One could intentionally neuter a speaker as above just to test a theory - does IMD increase with power? Not necessarily. Therefore your statement, “Higher efficiency/sensitivity means lower modulation distortion” is not true. As another example of why, if the driver was made with a 100 ohm voice coil instead of 4, it would have a much lower 2.83v sensitivity, but Doppler distortion, for example would be the same at each excursion point, but it would take much more voltage to achieve that same excursion. Therefore, the lower sensitivity driver has also lower IMD (per volt, but equal amounts per dB as mentioned in my previous post).
I know you want to argue your point about power and excursion while bringing in other variables - horn loading for example. I’ll copy and paste my last paragraph,
“Are there other variables that change in real life? Yes. But, as a thought exercise, one must look at at the AM and FM portions of IMD and sensitivity together in a vacuum and ignore the other variables. Once done, it’s easy to see how the two have nothing to do with one another directly, only indirectly through excursion.
I think you've misunderstood the point being made: the stimulus is different, but the fundamental system nonlinearities being characterized are the same. This does not contradict what you said and an example is given immediately following the part you quoted that demonstrates that one cannot, in general, derive intermodulation distortion from simple harmonic distortion data.
Chris A
Senior Member
That's a much better way to say it. Why not change the text of the advertisement to say that (assuming you are representing the company's interests here)?
Chris
May I say 'LOL' without without offending anyone?
So many platitudes, blanket statements. Even rather cheap drivers are perfect today compared to the past, a time from which this wisdom originates. The issue is already settled because - apparently - nobody knows what “not so great” or "inefficient speakers perform poorly at low volumes" means. These are the typical suspicions of people who never want to be satisfied with their hobby. Otherwise it would be over - a very simple logic. One might rather argue that the CO2 footprint is the decisive question. Because of efficiency, you get it.
Thanks to Dr Toole, sound quality can now be measured and classified inter-subjectively, despite all the justified criticism. What do these reheated ifs and buts want? Well, I, quite subjectively and personally with my listening experience, do not see the slightest connection between nominal efficiency and any parameter of sound quality - and I've had them all.
I am not associated with Purifi in any way.
OP
Luvchampagne
Active Member
- Thread Starter
- #56
Purifi PTT6.5X04-NAA-08 6.5" Alu midwoofer | HiFiCompass
What is on the test bench? The Danish company PURIFI continues very confidently march to the Olympus of High-End speakers and seems has squeezed everything out of its line of 6.5" speakers with paper cones, bringing them to perfection. First, the company has produced PTT6.5X04-NFA -01...
I believe these test results objectively show this. Do you disagree? @Lars Risbo could comment much more proficiently than me.
OP
Luvchampagne
Active Member
- Thread Starter
- #57
Looked up your setup and the spotlight turned on.
Do you think your emphasis on horn loaded solutions and Uber efficient speaker might be related to your Klipsch Jubilees? Not my jam but obviously everyone has their own tastes in speakers. My Salon2s are probably toward the other end of the spectrum. If all inefficient speakers were built like the 1980s I'd probably be jumping headfirst into the Klipsch camp as well.
It appears that many of your opinions and the scientific principles you cite are based on an all else being equal analysis and older designed speakers and drivers. In those use cases, I am in complete agreement with your thoughts and opinions.
Imho, the facts and data show otherwise for a number of well designed speakers 85db or lower sensitivity and for high performing drivers such as many of the Purifi drivers.
Chris A
Senior Member
Umm...Yes, I do.
Sorry to have to say this--but I'm a bit appalled at the manufacturer's 80 dB SPL rating for this woofer for the IM test. I've never taken (or otherwise tried to use) modulation/multitone measurements that low--because it's far too low SPL. The lowest I could imagine would be 90 dBFS/1m, with 100 dBFS/1m being much more realistic. Nonlinear distortion is defined as such because it is a nonlinear function of drive level, i.e., SPL.
Also, there is no thermal compression distortion plot that I could find. This is something that Erin posts as part of his Klippel NFS measurements. I assume that the founder here (Amir M.) also posts these results from his NFS. The drive level for this test should also be in the 90-100 dBFS/1m range, with higher SPL measurement levels being even more realistic.
Chris
Last edited:
OP
Luvchampagne
Active Member
- Thread Starter
- #59
Looneybomber
Active Member
- Joined
- Sep 23, 2022
- Messages
- 135
- Likes
- 162
I couldn’t follow your post. Two paragraphs and this, I think, was the point?
“I […] do not see the slightest connection between nominal efficiency and any parameter of sound quality”
For the most part, I agree. That said, do you disagree with anything in my post (did you understand my post?) or were you just using it as a springboard to begin your post?
