Here is a one page compilation of nonlinearities, by Klippel
https://www.klippel.de/fileadmin/_migrated/content_uploads/Klippel_Nonlinearity_Poster.pdf
I have found in my own tests that low end distortion is the greatest spl-related nonlinearity. It has many causes and should be studied with some specific tests (port congestion, BL nonlinarity, thermal changes, surround/cone resonances etc.) Tweeters suffer from this too and with poor xo they can even burn. I haven't noticed spl changes at all with low spl! Perhaps that can happen with some pro woofers?
Most drivers in Hificompass tests are mids or tweeters. DataBass is good source for woofers and subs. Zaph did distortion tests too Zaph|Audio
https://www.klippel.de/fileadmin/_migrated/content_uploads/Klippel_Nonlinearity_Poster.pdf
I have found in my own tests that low end distortion is the greatest spl-related nonlinearity. It has many causes and should be studied with some specific tests (port congestion, BL nonlinarity, thermal changes, surround/cone resonances etc.) Tweeters suffer from this too and with poor xo they can even burn. I haven't noticed spl changes at all with low spl! Perhaps that can happen with some pro woofers?
Most drivers in Hificompass tests are mids or tweeters. DataBass is good source for woofers and subs. Zaph did distortion tests too Zaph|Audio
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I was just about to point that out, but you caught it.
As good as the website is, I do wish they had used a steady SPL scale. They could make the top value 120 or whatever is good for the driver and leave it there.BTW, I don't see different drive levels for off axis.
Maybe I've always misunderstood fletcher munson, but my take has been at lower volume more bass SPL is needed to sound equal in level to treble.
And old loudness controls essentially boosted bass...for listening at lower levels.
I've thought fletcher munson curves say at higher volume levels, the perceived SPL difference between truly equal bass SPLs and treble SPLs leveled out and disappeared..
If that understanding is correct, wouldn't a system that stays linear with increased output, that needed bass boost at low output for equal level perception, not need the bass boost at high output?
That would work to make the high end sound less bright, wouldn't it?
Maybe I'm just seeing things backwards...I'm good at that Lol
fletcher munson curves reveal that our sensitivity to both low and high frequency varies with volume and that our ears have the flattest response at 85 to 90 db (our sensitivity to midrange is greatest at low levels)
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The trouble with loudness controls is that they aren't calibrated to an actual SPL at your listening position. The JRiver loudness can be, IIRC.
Also, we just don't know what the mix and master levels were, since there is no standard for music. But generally it's louder than typical domestic listening. To get the same tonal balance as the mastering some EQ will likely be needed.
Also, we just don't know what the mix and master levels were, since there is no standard for music. But generally it's louder than typical domestic listening. To get the same tonal balance as the mastering some EQ will likely be needed.
Based on the above logic, if it were only bass that were impacted, then you're correct. The bass boost makes it "sound" as if it's playing louder in terms of spectral balance in this context.
We tend to use Fletcher Munson as they were some of the earliest curves and ones we're familiar with, but it seems the standard got some love in 03 and is now known as ISO 226:2003.
Reviewing the ever-reliable (/S) wikipedia, it doesn't look like the treble differences are nearly what I'd thought. What's there is very minor (comparing 1k/10k), and the sub-1k seems to be the much more impacted bandwidth.
So WRT equal loudness looks like that's not it, my mistake. Insert crow in craw.
As an alternative- what if it's room reflection? Propagation loss increases with increasing frequency, so what if we're perceiving that much more energy as it crosses audibility/precedence thresholds as it's "overcoming" the losses at higher SPL (where at lower, the reflected energy might not be audible, it becomes so at higher SPL)
Just spitballing here- there are almost certainly several factors at play.
A quick look at the Beyma and a few others, let's me see 11v maximum sweeps.
And SPL graphs do appear to move linearly up and down within the various voltages.
But I think the 11v drive is too low to even encompass a normal 18dB headroom from no more than the rated sensitivity spec of 93dB. (Would need double that)
The ability to handle peak signals is such a biggie imo/ime.
That's what my previous post was meant to be about...the ability to handle peaks just plain melts as SPL is increased.
imo/ime, compression and increased distortion are often unwittingly lived with. Can we say ear bleed at low SPL ? 😉
Thanks for that badman,
Yes, I totally think your alternative can be a cause of my perceived spectral tilt with SPL.
Indoor RT60's, uneven across the spectrum will surely do that.
And outdoors, I hear less of the tilt phenomenon than in.
I'm getting more convinced my room(s) are non-linear as heck....
I mean bass doesn't cause my glass of wine to start walking off the table until I hit a certain SPL 😀
I've always operated under the premise that the little stuff matters and fixing as much of it as you can is worthwhile even when incremental audibility is limited. It's the same premise as generational recording losses- once you start stacking things you notice what you otherwise wouldn't have.
That all is why I run big setups. I've only heard a few small systems that didn't completely lose their marbles when pushed even moderately. Accordingly I triamp my horns with 200+ per driver 🙂
Yikes! If you are hitting 11 volts into a pair of 93dB/W speakers in a domestic setting, that's going to be loud. To be fair, the loudest I've ever had to go was 42V peak with 83 dB@2.83V speakers. And that was in my lava cave that soaked up sound like a sponge. Yeah, I still wanted more. 🙂
11V RMS where the tests are run would be 15.55 V peak. I think out of a 93dB driver that would be close to the levels I had with 42V on a 83 dB driver.*
I can understand wanting more, but for me an 11V sweep is enough to know how a driver will perform in the region that I use it.
*check my math
That's some loud stuff! My peaks are more in the few volts range most likely, as my RMS is typically something like .2V.
Dug out the graphs.
Turns out I'd mis-remembered the power levels. The final sweep was at 100V peak, and the impedance comes out around 6ohm. SPL should be somewhere near accurate.
I stepped up in 5dB steps for most of the curves, and then 3dB steps when things got loud. For the last few sweeps, I moved to a different part of the house, and had ear defenders on.
Note the compression coming in around 15kHz.
Distortion looked like this:
So, I'd expect the THD rise to leave them sounding poor before the frequency response shifts are noticeable.
Chris
Turns out I'd mis-remembered the power levels. The final sweep was at 100V peak, and the impedance comes out around 6ohm. SPL should be somewhere near accurate.
I stepped up in 5dB steps for most of the curves, and then 3dB steps when things got loud. For the last few sweeps, I moved to a different part of the house, and had ear defenders on.
Note the compression coming in around 15kHz.
Distortion looked like this:
So, I'd expect the THD rise to leave them sounding poor before the frequency response shifts are noticeable.
Chris
Nuts, I was about to comment on the spectacular polars.
I wonder whether the top end compression would be there if the sweep was done from the top down?
I wonder whether the top end compression would be there if the sweep was done from the top down?
What do you want to know about the XdW woofer? I remember more or less everything about it.
I don't remember how slow the sine sweep was for the Soundstage testing, but I was surprised by the results. Their testing is done in an anechoic chamber, so there is a lot of absorption, plus the small speaker is radiating into a full 4pi field. We duplicated their testing at NHT and more or less confirmed it. The sweep speed we needed to get their measured level of power compression was stupid slow. The purpose to their test is clearly to torture the speaker with moderately long term power to show where the system compresses the most.
The tweeter in that system has a neo motor with about a 1/2 lbs aluminum heatsink on the back. If you do that same test without the heatsink, the compression will be over 5dB in the tweeter range!
The results that Chris posted are really good. I've measured a lot of expensive prosound woofers that are much, much worse than this at high power. To really read this data, you need to subtract the curves from each other, because where the measurement has a steep slope, you can't see the compression. If you look at the 2nd and 3rd curves and the 3rd and forth curves at 150Hz, you can see that there is between 0.5dB of compression between the first pair and 1dB between the second pair, but the compression doesn't get much worse at higher levels.
This is a strange characteritstic of lightweight prosound woofers. They don't have much thermal mass, so they compress a small amount at low to mid power levels, but at higher power levels the airflow through the motor cooling paths removes heat from the coil a lot better. Their compression behavior is strongly related to excursion.
I don't remember how slow the sine sweep was for the Soundstage testing, but I was surprised by the results. Their testing is done in an anechoic chamber, so there is a lot of absorption, plus the small speaker is radiating into a full 4pi field. We duplicated their testing at NHT and more or less confirmed it. The sweep speed we needed to get their measured level of power compression was stupid slow. The purpose to their test is clearly to torture the speaker with moderately long term power to show where the system compresses the most.
The tweeter in that system has a neo motor with about a 1/2 lbs aluminum heatsink on the back. If you do that same test without the heatsink, the compression will be over 5dB in the tweeter range!
The results that Chris posted are really good. I've measured a lot of expensive prosound woofers that are much, much worse than this at high power. To really read this data, you need to subtract the curves from each other, because where the measurement has a steep slope, you can't see the compression. If you look at the 2nd and 3rd curves and the 3rd and forth curves at 150Hz, you can see that there is between 0.5dB of compression between the first pair and 1dB between the second pair, but the compression doesn't get much worse at higher levels.
This is a strange characteritstic of lightweight prosound woofers. They don't have much thermal mass, so they compress a small amount at low to mid power levels, but at higher power levels the airflow through the motor cooling paths removes heat from the coil a lot better. Their compression behavior is strongly related to excursion.
another (2) question(s) does a sine sweep have the ability to show inter modulation?
would pink noise reveal anything different?
would pink noise reveal anything different?
So you're playing Beethoven's 9th quartet softly late at night. And you say, gotta crank up the bass or, at this soft volume, I can't hear the cello in that amazing second movement.
What do you get? Is it the sound of the quartet in a concert hall as if you had plugs in your ears to lower the volume? Is it the quartet a long ways away but listening with hearing aids?
Or is it what I say HiFi is all about: hearing the score as Beethoven intended, fostered by choices the production team made?
BTW, in ancient times, fancy pre-amps (like some Kenwood Basic) had "4-gang" controls that did a really great job of replicating F-M and at all volume levels, providing you did the gain management reference properly.
B.
What do you get? Is it the sound of the quartet in a concert hall as if you had plugs in your ears to lower the volume? Is it the quartet a long ways away but listening with hearing aids?
Or is it what I say HiFi is all about: hearing the score as Beethoven intended, fostered by choices the production team made?
BTW, in ancient times, fancy pre-amps (like some Kenwood Basic) had "4-gang" controls that did a really great job of replicating F-M and at all volume levels, providing you did the gain management reference properly.
B.
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Tricky doing these distortion measurements. When the speaker level is low, the residual crap is relatively louder, thereby making the distortion seem worse. Still meaningful for some purposes, but hard to address the question of this thread.
The place where Fletcher-Munson comes home to really bite you is in the audibility of sub-woofer distortion. Even a little bit of 3rd harmonic will be much more audible relative to the fundamental than in higher ranges. And provides an audible "reveal" for the location of a sub like the proverbial "sore thumb" sticking out.
The place where Fletcher-Munson comes home to really bite you is in the audibility of sub-woofer distortion. Even a little bit of 3rd harmonic will be much more audible relative to the fundamental than in higher ranges. And provides an audible "reveal" for the location of a sub like the proverbial "sore thumb" sticking out.
1 - By definition, no. There's only one frequency being put into the system. That said, there's usually a decent correlation between HD and IMD.
2 - I doubt it. REW has good reasons for using swept sine tones. The paper mentioned in the Help file is this one: http://www.four-audio.com/data/MF/aes-swp-english.pdf
Chris