Complaint thread about speaker measurements

[amirm]

On listening tests, it is become a major bottleneck to testing. Do you all want me to hold up reviews in general and speakers in the specific until I listen?

Formal listening tests are far in the future so let's not push for rigor there.

 

[spacevector]

I did that with a powered monitor which I have not reported on. It is revealing but also time consuming to try all these alternatives.

Understand completely. This speaker measurement/review binness is cramping your fast 'n furious style a bit, huh?

 

[digitalfrost]

On listening tests, it is become a major bottleneck to testing. Do you all want me to hold up reviews in general and speakers in the specific until I listen?

Formal listening tests are far in the future so let's not push for rigor there.

While referencing measurements to your listenting impressions is interesting, I am much more interested in the data. We have enough listening impressions of speakers on the internet, that we could compare to the data.

 

[amirm]

Understand completely. This speaker measurement/review binness is cramping your fast 'n furious style a bit, huh?

On the hardware side, no. I am getting pretty quick in running the speaker measurements. About 10 to 15 minutes of setup, and one hour of measurement time. It is less manually intensive than electronics testing!

I could do two or three reviews a day if all I had to do was post the spinorama graphs. Getting bogged down with give me this and that graph is adding a lot of time and effort to capture, document and post the results in the review.

 

[napilopez]

To put some context: Listening and writing up thoughts takes a whole lot of time, especially doing so with any semblance of serious critical analysis. Most people who write reviews (like me) spend weeks or sometimes months listening to a speaker, not a few hours =]. Not that you actually need that long, but still.

Even with a manual turntable setup, I find measuring takes a lot less time than listening and taking notes and writing a written review that flows decently, not to mention properly positioning speakers and swapping components and whatnot. Imo best to leave the listening tests informal fo the stated purpose of the site. Listening before measuring is probably ideal, but could be a big bottleneck to measurements if aiming for a speedy pace. It can be a lot more convenient to measure several speakers back to back, for example, than to commit to listening before measuring every time. And you need to look at the measurements to make sure everything is kosher, so you can't just measure a bunch and then ignore the data until after you've listened.

 

[aarons915]

On listening tests, it is become a major bottleneck to testing. Do you all want me to hold up reviews in general and speakers in the specific until I listen?

Formal listening tests are far in the future so let's not push for rigor there.

I for one don't, I'd rather see you crank out more measurements.

 

[restorer-john]

On listening tests, it is become a major bottleneck to testing. Do you all want me to hold up reviews in general and speakers in the specific until I listen?

Yes.

Buy/build a speaker switching unit, make some space in your proper listening room, insert a reference pair of two ways alongside your big bangers and compare the SUT (speakers under test) to the references. You'll need fair references for the two ways, not some cheap-ass powered "near field monitors" With powered speakers, you can still compare the ML-passive chain to the active via line level matching into the actives.

 

[edechamps]

There's alot of noise about possible differences in the graph if we measure with a different reference axis, but I think that's 98% irrelevant.

IMHO, the main reason why I'd like @amirm to use the correct reference axis is because that's what CTA-2034-A specifies, and the CTA-2034 procedure for determining the reference axis is easy: if the manufacturer provides it, then use that, otherwise it's basically "do what you think is best", so no changes needed in that latter case. It takes basically no effort to follow the proper, standardized procedure, so I really don't see why Amir stubbornly refuses to do it.

I can concede that it might not be that important in terms of correlating with audible differences, but it would make Amir's measurements more consistent with other third-party measurements, which is a good thing. Multiple parties all doing measurements in a standard way makes it possible to spot potential problems or interesting patterns, and promotes repeatability and replication, which is one of the pillars of good science. This is Audio Science Review, after all.

If Amir doesn't want to remeasure the KH 80 because he thinks that's not a good use of time, then that's one thing, and I can understand that. I'm just hoping he will rectify the issue on future reviews. So far it doesn't look like it, given that he only mentioned this subject in his last two reviews in the form of petty jokes. Which, by the way, is worrying for another reason: an outsider who's not privy to the debate will likely not get these jokes, and from that perspective Amir might look like someone who doesn't care about rigour or accuracy. That's not exactly the best way to get people to trust these reviews.

So can we please, please, please follow CTA-2034 from now on and put this issue to bed once and for all?

 

[LTig]

Yes, compression would be a good test. Good 'speakers don't do more that 1dB or so at 100dB SPL, but I have no idea how smaller 'speakers perform. I'd would guess that some, like the LS3/5a won't even get to 100dB, at least not at 2m.

This would be really cool.

This is a measurement you never see elsewhere. It would be a coup of sorts for ASR!

Several audio mags publish compression tests, like the German stereo and stereoplay. They show FR at 4 different SPLs in 5 dB steps.

I think an even better graph would show the difference between FRs at several higher SPLs to the FR at the lowest SPL, e.g.

• FR @ 100 dB - FR @ 80 dB
• FR @ 95 dB - FR @ 80 dB
• FR @ 90 dB - FR @ 80 dB
• FR @ 85 dB - FR @ 80 dB
• FR @ 80 dB (not shown)

Any bumps in FR then would not matter and compression should be much easier to notice. One could also overlay the graphs:

• FR @ 100 dB - FR @ 80 dB - 20 dB
• FR @ 95 dB - FR @ 80 dB -15 dB
• FR @ 90 dB - FR @ 80 dB - 10 dB
• FR @ 85 dB - FR @ 80 dB - 5 dB
• FR @ 80 dB (not shown)

For very small monitors like the KH80 I would skip the 100 dB test - at least for passive one which have no protection against overload. Tests should be fast to not stress the speakers. I'm sure those people who send in their speakers want them back in same condition as sent.

 

[restorer-john]

For very small monitors like the KH80 I would skip the 100 dB test - at least for passive one which have no protection against overload. Tests should be fast to not stress the speakers. I'm sure those people who send in their speakers want them back in same condition as sent.

No, that's the problem. You are either properly reviewing the speakers or you are pissing around babying them for fear of possibly damaging them. That makes for a completely useless review.

Both speakers and amplifiers need to tested to determine their rated performance limits. Presently, this is not done and the reviews are therefore incomplete. In my opinion, they do not give an remotely accurate representation of the actual real-world performance of the products, and as such, they have limited value. Certainly to me. I wouldn't buy a speaker or an amplifier based on the content of the ASR reviews. I would however buy a D/A converter based solely on the ASR reviews as they are comprehensive.

Speakers can be tested with tone-bursts if you're scared of blowing them up. Enough excuses about not wanting to damage something. It's BS Amir. I haven't blown up a decent amplifier in 35 years testing. Speakers need to be tested against their specifications and that includes a maximum power where THD remains at a reasonable level across the audible bandwidth. Compression or even a linearity test up to maximum power is needed. What happens to these little 6.5" 2 ways after 15 minutes of loud-ish music? I'll tell you, the dynamic compression/distortion goes through the roof. These are factors that Amir can't/won't test in his garage system. Maybe not in his lounge-room either. So where does that leave people?

With active speakers, you are testing the amplifier/s as well. You cannot make a recommendation on the product if you don't even test part of it. They should be run at 1/5-1/3 rated output (measure it at the driver terminals) for an hour prior to all the testing. Give them pink noise, put them in a padded box and go shopping if it's too loud. If they blow up, they are rubbish and should be called for what they are.

Who cares if a speaker is dead flat at 1W or 5W but completely falls apart to distort, pole the voice coil or lose a tweeter when the level is increased? How linear is the speaker at various input levels up to rated power? Does the speaker produce huge amounts of frequency doubling at LF or port noise at medium/high powers? Is the rated power the manufacturer quotes realistic or complete fantasy?

This is what we need to know.

 

[edechamps]

I wholeheartedly agree with the requests for measuring the maximum SPL capability of a speaker, e.g. compression tests. Just like frequency response measurements this is important data that is seldom published anywhere.

If there are no max SPL measurements then we will likely end up with dubious comparisons where, say, a massive Neumann KH 420 would be considered equivalent to a tiny Neumann KH 80 simply because they both have an excellent frequency response. In reality there is a ~14 dB max SPL difference between these two speakers, but it would be impossible to tell from the current set of measurements. As @restorer-john just said, this is really incomplete data.

I understand the issues about possibly damaging speakers that are loaned. Maybe a "gentle" procedure can be used where we stop increasing SPL as soon as the onset of compression is observed? Or perhaps some of the people who lend the speakers would be okay with taking the risk.

 

[Tks]

So far I am running into a roadblock that IMD tests requires a license to purchase them!

So annoying.. It's like microtransactions in video games.

 

[Blumlein 88]

This would be really cool.

This is a measurement you never see elsewhere. It would be a coup of sorts for ASR!

I think power compression is a major factor in listening enjoyment, right? Probably much moreso than THD to a point. I could be wrong. If anybody can point me to resources on it I'd love to learn more. It's a little hard to Google for because it's hard to separate from results relating to other forms of compression (lossy data compression via mp3, etc)

Soundstage.net tests at 90 and 95 to show comparitive FR and level.

 

[hardisj]

For speakers, I'm not sure how much effort I would put in to IMD. The main benefit of IMD is to tell you what distortion components come from excursion. The crossover should be above Fs which should limit excursion and inductance-driven distortion components. A loudspeaker will have a properly implemented crossover which will limit excursion and the effects that IMD would show. Now, for raw driver tests? Sure. Especially for woofers you plan to push to the ragged edge.

But, I do see a benefit in stress testing a loudspeaker with THD measurements. I get that now and again you'll be gifted a unicorn and the owner won't want you to push the limits much. But even 90dB & 96dB (referenced to 1m) isn't terribly stressful unless the speaker is incredibly inefficient and/or poorly built with respect to (tweeter, mainly) crossover. Doing the incremental tests would be useful information even if you capped it at 96dB. I tested raw driver... DRIVERS... no crossover applied ... for years. Probably above 100 of all sorts. The only one I ever blew was a subwoofer and that was because I forgot to adjust the output voltage. If I can do that with raw drivers then 96dB on a standard sensitivity speaker is not going to cause any issues in terms of destruction or damage. None.


I mean, heck, if this mid-70's sensitivity 2 inch driver can take 90dB and 96dB @ 1m (as shown below) then a loudspeaker certainly can.
https://web.archive.org/web/2018021...ic-elements-tebm35c10-4-miniature-bmr-driver/

 

[Fluffy]

I don't use their amplifier (it is too low power made for driver testing). The one I am using is one that I have reviewed before (Behringer A500): https://www.audiosciencereview.com/...easurements-of-behringer-a500-amplifier.5070/

This is kind of curious you are using an amp that measured poorly and you didn't recommend. Shouldn't these measurements be done with a better amp?

 

[LTig]

With active speakers, you are testing the amplifier/s as well. You cannot make a recommendation on the product if you don't even test part of it. They should be run at 1/5-1/3 rated output (measure it at the driver terminals) for an hour prior to all the testing. Give them pink noise, put them in a padded box and go shopping if it's too loud. If they blow up, they are rubbish and should be called for what they are.

With this approach you won't find many people sending in their speakers ...

PS: Putting an active speaker in a padded box and then run it at high power is a recipe to run into thermal problems due to missing air flow. This is not normal usage.

 

[restorer-john]

I understand the issues about possibly damaging speakers that are loaned. Maybe a "gentle" procedure can be used where we stop increasing SPL as soon as the onset of compression is observed? Or perhaps some of the people who lend the speakers would be okay with taking the risk.

Short cycle toneburst testing is the safest. It takes more power than Amir has on tap on tonebursts to damage most woofers. My concern would be the HF testing with his ML. It's a Class D AFAIK and we have no idea how it would like high power impulse testing. I certainly wouldn't use it for that.

I'd buy a really big old Crown Macrotech 2400 or similar for really cheap and restore it (if it needed it). Something that can dish out a 1.5kW clean @ 8R in mono. Use it for the non-Klippel power/impulse testing

 

[hardisj]

This is kind of curious you are using an amp that measured poorly and you didn't recommend. Shouldn't these measurements be done with a better amp?

I would personally use a better amp but in his defense the only time he needs a lot of 'clean' power is when he's testing very low sensitivy speakers. As long as he tests products that are above 80dB @ 1w/1m then he'll be OK to do 96dB @ 1m output testing. But lower than that and he's running that amp on the ragged edge of what his test results indicate.

 

[restorer-john]

PS: Putting an active speaker in a padded box and then run it at high power is a recipe to run into thermal problems due to missing air flow. This is not normal usage.

OK, put it in a big padded cupboard- how's that? The point is this, if you don't confirm the rated specifications by actual testing, what have you achieved?

Fictitious example: "Here's my 450W rated, USD$20K DSP 5 channel Class D amplified speakers and I "tested" them at between 1 and 10W and they performed really well. I didn't test them above that level in case they got damaged"

 

[spacevector]

A loudspeaker will have a properly implemented crossover which will limit excursion and the effects that IMD would show.

Most passive speakers don't have a high-pass crossover though, no? So excursion due to bass/sub-bass can potentially get pretty large. If intending to use full-range, may be IMD can provide some useful information for the potential buyer?