PS Audio sent Erin their speaker??!!

[Penelinfi]

There's always seems to be branding more than necessary on speakers/equipment . Kind of detracts from the look usually . Especially if it's descriptive text. Next are logos that seem out of place or "cheap" looking. Some silvery curvy logo on a nice neat clean lines speaker or vice versa

 

[amirm]

Just because Prof. Klippel used a small sample speaker, short-term compression measurements are still interesting for every speaker

I wasn't talking about the speaker used. Dr. Klippel specifically said short-term compression was an issue with tiny smart speakers and such.

Regardless, if a speaker response can change with just quick sweep, that means that many factors can impact the accuracy of measurements such as what was run before, how warm the environment is, etc. Let's remember, none of these tests have been verified to be correct. We don't even know if you ran them twice in the row you get the same results.

 

[Duke]

I wasn't talking about the speaker used. Dr. Klippel specifically said short-term compression was an issue with tiny smart speakers and such.

Regardless, if a speaker response can change with just quick sweep, that means that many factors can impact the accuracy of measurements such as what was run before, how warm the environment is, etc. Let's remember, none of these tests have been verified to be correct. We don't even know if you ran them twice in the row you get the same results.

From a post by Floyd Toole on another forum:

"The audibility of power compression in its many variations probably could use some more research to define what is audible and what is tolerable. The magnet heating that you describe is important in pro audio sound reinforcement systems where the loudspeakers are required to work at or close to their design limits for long periods. Such heating and cooling has a very long time constant. This is not the case in most home systems. Although the modification of motor strength through magnet heating is a factor, most of the audible effects are from voice coil heating, which has a much shorter time constant. I just saw a test of a high-end audiophile speaker that in going from an average level of 70 dB (loud conversation, background music) to 90 dB (a moderate crescendo, or foreground rock listening) lost about 4 dB in output over about 3 octaves in the mid-high-frequency range. It became a different loudspeaker at different listening levels."

The term Earl Geddes uses for the effect of this short-time-constant voice-coil heating is "thermal modulation".

 

[jhaider]

I wasn't talking about the speaker used. Dr. Klippel specifically said short-term compression was an issue with tiny smart speakers and such.

Regardless, if a speaker response can change with just quick sweep, that means that many factors can impact the accuracy of measurements such as what was run before, how warm the environment is, etc. Let's remember, none of these tests have been verified to be correct. We don't even know if you ran them twice in the row you get the same results.

In the alternative, it means the speaker’s FR varies with level. And sometimes that explains sonic effects that seem to have no other explanation. One example - a line of speakers came out with cheap AMT tweeters. They generally were well to fawningly reviewed (the company also did a lot of marketing…) and generally measured mediocre with the typical “behold my exotic tweeter” treble rise. I heard a few models, and was consistently puzzled by what I perceived lack of treble dynamics, and a lack of upper mids at symphonic volumes. Then I saw some measurements in Soundstage that showed significant compression from said cheap AMT when played at (IIRC) 95 dB average compared to (IIRC) 75 dB average. Then what I perceived kind of clicked. Likewise, IME speakers that do well down in the upper bass on Erin’s compression testing (the driver/speaker size to performance ratio probably being highest on JBL 708 among the speakers Erin has tested) tend to get a lot louder than they sound.

 

[nerdemoji]

If these results are true, this would almost certainly be audible

 

[amirm]

From a post by Floyd Toole on another forum:

We are not seeing anything remotely like that (4 dB loss across three octaves). I am sure there are some way under-designed drivers out there that have issues like this. The topic here are Erin publishing measurements after measurements on every speaker claiming to show reduction or in some cases increase (!) in relative output. As Dr. Toole said, this needs to be studied. You can't just throw the measurements in front of people and call it "compression." The only clear case of short-term compression I have seen so far are powered monitors with clear limiting in the amplification.

Do you want to run the same test on your speaker and report back on a) what you see and b) if you believe it to be "compression?"

 

[jhaider]

Fair. But let me ask you this: what else have you listened to in your own home, besides these Revel's and which model Revel? Everything is relative, for example if you never been in a car that went 150mph, 100mph is fast.

Prior to my Neumann KH 120, Perlisten S7t and Ascend Sierra LX, the best speaker (objectively and subjectively) I had was the Revel F226Be and the Revel M16 (still have it, but demoted to my wife's office).

To @Chester's point, tbh I don't think there's anything super special about KH 120 II imaging. Don't get me wrong, they are truly exceptional nearfield/desktop speakers (I limit myself to that because I've only used them in that context) and they image just fine, if much smaller in scale (because nearfield). Certainly the immersive system stomps all over them in terms of every aspect of spatial reproduction, comparing the same stereo recordings and upmixing with Auro. But even limited to stereo I don't think they're anything special in the imaging department compared to either of our other stereo setups (Revel Gem2s + multisubs EQ'ed with Dirac Live Bass Control; NHT C-3 + 2 subs EQed with RoomPerfect).

Perhaps people who don't use room correction will find bigger spatial differences between speakers (and thus, be more inclined to demand augmentation to mono evaluation) given the comparatively worse pair matching at the listening position? @j_j had a good deck on how matching speakers' response improves imaging. See http://www.aes-media.org/sections/pnw/ppt/jj/room_correction.ppt, at 28.

 

[Duke]

Do you want to run the same test on your speaker and report back on a) what you see and b) if you believe it to be "compression?

It sounds like my post was interpreted as taking sides against you in an ongoing debate. I thought I was just posting potentially relevant and interesting information.

No I do not want to run the same test on my speaker and report back on a) what I see and b) whether I believe it to be "compression". I have no dogs in what apparently is a fight. Erin's compression tests are not on my radar screen.

 

[amirm]

Then I saw some measurements in Soundstage that showed significant compression from said cheap AMT when played at (IIRC) 95 dB average compared to (IIRC) 75 dB average.

Soundstage (really NRC) does it correctly:

Notice the proper 50 dB vertical axis to account for myriad of unknowns and accuracy issues. Erin zooms that out almost 10X to just 6 dB vertical scale!!! If you see issues in Soundstage tests, then yes, it is a problem. And it would show just as readily in my sweeps as I showed earlier.

I just showed the differential in KEF R11 Meta:

No doubt if I made the differential test like Erin, there would be a curve showing ups and downs. But do you really consider any of the frequency curves above different from each other??? We have so much higher order issues that this kind of minutia is just noise.

If nobody looked at the graphs it would be one thing but now I read people saying that graph is one of the most important things in Erin's testing! Talk about creating a non-problem and getting people concerned for no good reason.

 

[jhaider]

Notice the proper 50 dB vertical axis to account for myriad of unknowns and accuracy issues. Erin zooms that out almost 10X to just 6 dB vertical scale!!! If you see issues in Soundstage tests, then yes, it is a problem. And it would show just as readily in my sweeps as I showed earlier.

I take your point and agree to some extent. I think it's academically interesting to see zoomed in, but is the difference between 0.5 ond 0.8 dB compression audible? Doubtful. Do people bitch and moan about it in stupid ways? Sure. OTOH, there's a whole subculture here dedicated to bitching and moaning about irrelevant differences in SINAD in pointless-me-too-whatever commodity electronics products, so...

I just showed the differential in KEF R11 Meta:

I like that. Please keep doing it. (Though a normalized difference graph a la Soundstage would be easier to read IMO.)

If nobody looked at the graphs it would be one thing but now I read people saying that graph is one of the most important things in Erin's testing! Talk about creating a non-problem and getting people concerned for no good reason.

The two points are mutually exclusive: one can have some quibble about the presentation, while thinking the data is very important and useful.

We are not seeing anything remotely like that (4 dB loss across three octaves). I am sure there are some way under-designed drivers out there that have issues like this. The topic here are Erin publishing measurements after measurements on every speaker claiming to show reduction or in some cases increase (!) in relative output.

First, not every speaker. The ones with really really good drive units, and especially good big drive units, come out looking better in Erin's compression testing than speakers with typical home audio smallish diameter, small voicecoil, minimal thermal management drive units. So just based on that kind of smell test intuition there's some value to it.

Also, I disagree with your implication that showing increases in level demonstrates flaws in the testing method. Rather, looking where levels increase disproportionately points to reasonable causal mechanisms, such as port issues/passive radiator nonlinearity, cabinet resonances, maybe crossover issues, etc.

 

[amirm]

The ones with really really good drive units, and especially good big drive units, come out looking better in Erin's compression testing than speakers with typical home audio smallish diameter, small voicecoil, minimal thermal management drive units.

Again, unless someone shows some temperature probe measurements, there is no reason to think these are thermal effects. A different driver may just have lower distortion -- something we already measure and show directly instead of implicitly through this graph.

 

[thewas]

From a post by Floyd Toole on another forum:

"The audibility of power compression in its many variations probably could use some more research to define what is audible and what is tolerable. The magnet heating that you describe is important in pro audio sound reinforcement systems where the loudspeakers are required to work at or close to their design limits for long periods. Such heating and cooling has a very long time constant. This is not the case in most home systems. Although the modification of motor strength through magnet heating is a factor, most of the audible effects are from voice coil heating, which has a much shorter time constant. I just saw a test of a high-end audiophile speaker that in going from an average level of 70 dB (loud conversation, background music) to 90 dB (a moderate crescendo, or foreground rock listening) lost about 4 dB in output over about 3 octaves in the mid-high-frequency range. It became a different loudspeaker at different listening levels."

The term Earl Geddes uses for this short-time-constant voice-coil heating is "thermal modulation".

The senior engineer of B&O also wrote an interesting article about it and includes a thermal compensation in his designs:

B&O Tech: Thermal Compression Compensation

#9 in a series of articles about the technology behind Bang & Olufsen loudspeakers Recipe for`Befuddled Speaker Enthusiast´ Makes: One individual with reduced faith in louds…

www.tonmeister.ca

Here is also another interesting thermal aspect I would have never thought about:

B&O Tech: The Heat of the Moment

#39 in a series of articles about the technology behind Bang & Olufsen loudspeakers “If you saw a heat wave, would you wave back?” – Steven Wright Part 1: The My…

www.tonmeister.ca

 

[restorer-john]

Thermal compression from heated VCs and magnet assemblies are massively exaggerated in smaller, simpler loudspeakers. A 6.5" two way is easy to hear compression related changes to the entire repsonse as they heat up. Obviously, the TC of tweeters is much faster, but they are not immune to compression either.

I've heard it so many times when playing spirited levels of dynamic content on small speakers. It reminds me to use a bigger three way or multi driver floorstander.

It's fun to point a thermal camera at the woofers and tweeters during spirited sessions. Woofers with an alloy phase plug definitely run cooler for the same power levels.

Something I never considered until I had a thermal camera was the woofer cone roll surrounds heat up from movement/internal friction.

 

[CleanSound]

To @Chester's point, tbh I don't think there's anything super special about KH 120 II imaging. Don't get me wrong, they are truly exceptional nearfield/desktop speakers (I limit myself to that because I've only used them in that context) and they image just fine, if much smaller in scale (because nearfield). Certainly the immersive system stomps all over them in terms of every aspect of spatial reproduction, comparing the same stereo recordings and upmixing with Auro. But even limited to stereo I don't think they're anything special in the imaging department compared to either of our other stereo setups (Revel Gem2s + multisubs EQ'ed with Dirac Live Bass Control; NHT C-3 + 2 subs EQed with RoomPerfect).

Perhaps people who don't use room correction will find bigger spatial differences between speakers (and thus, be more inclined to demand augmentation to mono evaluation) given the comparatively worse pair matching at the listening position? @j_j had a good deck on how matching speakers' response improves imaging. See http://www.aes-media.org/sections/pnw/ppt/jj/room_correction.ppt, at 28.

Ok, if you've heard of them before and that is your experience, fine.

Perhaps you are comparing them to other speakers that images very well too. For me, the best (and most expensive) speakers I've own before them are the Revel F226Be, so that is my frame if reference.

 

[restorer-john]

See http://www.aes-media.org/sections/pnw/ppt/jj/room_correction.ppt, at 28.

What a truly disastrous powerpoint presentation, an utter and complete yawnfest.

 

[Andysu]

paul has been to the uk ! how he miss my home ? , just kidding

 

[Anton D]

Subjective objective...I love the way Erin did the review, listened subjectively first, and then did the measurements. Bravo Zulu!

As it should be!