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What's interesting about the original is that Bose calculated the necessary target curves without modern test gear.
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ErinsAudioCorner
- Thread starter hardisj
- Start date
@hardisj Thanks for the great work! Your reviews so far are unmatched in terms of the level of detail.
I also like the fact that you display the spectrograms with 3dB stepped colors - as it is usual and allows comparisons to other measurements.
Didn't expect that in terms of compression a multitone measurement would differ so much from a pink noise measurement - or did you use a sliding sine in the old measurements?
There are a few frequency ranges that behave somewhat unexpectedly and change their behavior completely during the 9V measurement (see blue rectangles).
Are you sure that the measurement device, the microphone itself or other objects in the measurement room do not contribute to the measured signal. In such a case, room compensation would be of little use.
Is it possible to evaluate the measurements first from 3V and then normalize them to 3V, this would correspond approximately to your old compression measurements.
I also like the fact that you display the spectrograms with 3dB stepped colors - as it is usual and allows comparisons to other measurements.
What surprises me a little are the striking deviations from your previous compression measurements of the Neumi BS5 (must grin every time I write the name of the speaker "BS5" - with age you become infantile again).
Didn't expect that in terms of compression a multitone measurement would differ so much from a pink noise measurement - or did you use a sliding sine in the old measurements?
There are a few frequency ranges that behave somewhat unexpectedly and change their behavior completely during the 9V measurement (see blue rectangles).
Are you sure that the measurement device, the microphone itself or other objects in the measurement room do not contribute to the measured signal. In such a case, room compensation would be of little use.
Is it possible to evaluate the measurements first from 3V and then normalize them to 3V, this would correspond approximately to your old compression measurements.
OP
- Thread Starter
- #403
I noticed the same differences last night and I, too, find it interesting. However, the original measurement was taken at 0.25m using a single tone stimulus: 100 log-spaced tones between 50Hz to 10kHz, played one at a time. The new is 1 meter, multi-tone (which you can see in the video I shared). So, it’s not an apples to apples comparison.
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Okay, I thought you used noise to measure frequency response.
So there remains the strange behaviour of the 9V measurement compared to those with lower voltage.
The reason for the termination of the measurements at 1.4kHz is still obvious to me. An antiphase resonance produces a deeper and deeper dip with increasing voltage (first purple rectangle).
Astonishing are the resonances at 4.8kHz and 5.5kHz (second purple rectangle) - are these influences due to the woofer break-up or resonances of the tweeter?
Very strange is the behaviour in the blue marked frequency ranges 1) - 4).
There are grey lines above and below the red line. A dip suddenly changes to peak 1) and vice versa 2).
The resonance modes of a driver usually change with frequency and not with amplitude.
Hence my question whether other resonance sources can be excluded.
OP
- Thread Starter
- #405
I use a log sweep to gather FR.
The HD and Compression tests are done separately; not with the standard FR measurements. The HD and Compression tests I've previously shown are done using a single tone in the manner I described above.
1-4) I do agree they are perplexing. However, if you look back at my original compression plot you can see at least one occurrence of this at ~430Hz (your #2). And this was measured in the nearfield at 0.25m:
Also, keep in mind that - because I was using singular, log spaced tones and not a sweep or multitone stimulus - that the previously provided measurements might not have hit the exact same frequencies in the way the multitone measurement does. Not saying that is the sole cause for the differences. Just noting it as a potential difference. Nevermind the fact that a NF measurement of a speaker itself can be misleading, depending on how the wavefront is formed at the microphone position. I'll address this below as well.
Now, having said all of that, let's look at another example. I measured *a new* speaker this week (data hasn't been posted yet). I ran this set of measurements in the exact same way and the exact same day I tested the Neumi with ISC+MTON. Literally, I tested the Neumi with MTON, I took it off the stand, I put the other speaker on the stand at the exact same position, not moving the mic or anything else, and then tested this new speaker with MTON. They are under the exact same conditions; tested about 10 minutes apart. Not even the temperature was different. Therefore, they are directly comparable in every way. Below are the results:
To make it easier to see the differences, here is the 9V from the new speaker (green) overlaid on the Neumi BS5 results (gray/red) where 9V was the failure point. If the room was an issue, as you are concerned, this would show up in the results as numerous overlapping points. As you can see, there is no distinct correlation in this regard.
and to make it much easier to see...
Therefore, I have no doubts the measurements are free of room conditions, as should be the case with using Klippel's ISC and MTON module in conjunction.
------------- (break) --------------
Regarding the purple boxes, it's hard to say without diving further. Below is the Fundamental+HD at 2.83v/0.5m. The Absolute PHD (a predictor of audible distortion, iirc) is up around that range. The HD lines also show an uptick in distortion between 400-700Hz and 1-2kHz.
Then, below is the NF response (at 2.83v, 0.50 inches from the baffle, SPL scaled down). You can see there are some higher levels of distortion until ~2kHz before falling off.
It does seem, though, that there is indeed woofer breakup in this region. Though, IIRC, there was also some lingering port resonance in this area. It's been a while since I've taken my compressible flow course but I wonder if the port is the root cause with the purple boxes.
Notice the two distortion profiles are not the same. Not even in the 200-1kHz region where the mid/woofer is dominant (meaning, I'm not concerning myself with tweeter response in a comparison of a NF woofer measurement). And notably the 3rd order distortion profile lies almost exactly with the 2nd order in the NF while this is not true in the 0.5m measurement. This is a prime example of how varying measurement methods can lead to different results. Even with the exact same stimulus applied. This isn't to say either method is wrong. It is to say that each can be effected by conditions. Aside from my own tests, this is something to keep in mind with others' results, like Amir's. Comparing one person's results to another is likely to cause issues because the setups are not the same. They really should be compared within their own set.
However, with the ISC + MTON modules, that is not the case. If another person was to follow the same protocol I am using then we should have comparable results.
Bottom line:
As of this very moment, I am 100% confident in the use of my measurements to extract maximum SPL. To be blunt, I am much more confident in this method than ... the other methods we have been presented. My only ongoing task is to determine which way to apply stimulus (which type; how long). There are a multitude of IEC variations here so I just need to pick one (or two) and roll with it.
FWIW, if you want to see the processes I am using, you can watch/view the Webinars here. Particularly numbers 4 and 5. I have worked directly with Klippel on the interpreation of these since they have been released but was unable to use them until they released the newest updates (they were using their beta versions in the Webinars). That's why I was so excited to start testing them when they released the updates this week.
http://www.klippel.de/know-how/education/webinars.html
I hope that helps address your concerns. Trust me, it's different for me as well and I spent hours (and hours, and hours) combing through the data, re-running over and over and trying to make sure that what I am presenting is accurate and reproducible. I don't take this task lightly. Presenting data to a friend and having it wrong is one thing... presenting it to the masses and having it wrong is something else altogether. I do my very best to be rigorous and document updates but, frankly, there are so many details that go in to my efforts that I don't have the time to post them and I honestly doubt anyone cares. Maybe I should set up a live web-cam next time I run a speaker through the paces and you guys can follow along with me for the literal 10+ hours I spend testing and verifying/analyzing data. I'm not at all exaggerating.
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OP
- Thread Starter
- #406
A friend was kind enough to provide me with some information I needed from the IEC 60268-21. Basically, it says "hey, measure how you want as long as you tell people how you're measuring". Go figure.
This video expands on the previous one because I have now decided on a specific method using Klippel's template (discussed below).
If you saw the previous video where I discussed the MTON and ISC modules used in conjunction, then you don't necessarily have to watch this. However, since I have decided on a measurement method, I made this updated video so everyone can see how I am and will be performing my max SPL testing. In this video, I am measuring at 1 meter using the ground plane technique to improve signal to noise where ground plane increases the SPL by 6dB. However, this does not effect the measurement result in any way other than by simply adding 6dB to the max SPL which I will deduct when presenting the results. If you are wondering why I am not measuring at 2 meters to balance out the 6dB increase, it is, again, to increase the SNR. Moving the mic to 2 meters wouldn't improve accuracy and would just lower the noise floor. Do note, however, for larger (tower) speakers, I will measure as far away as is necessary to be in the "far field".
The measurement follows the IEC 60268-21 Long Term SPL protocol, per Klippel's template, as such:
Each voltage test is 1 minute long (hence, the "Long Term" nomenclature).
The thresholds to determine the maximum SPL are:
Again, I am adhering to a standard. However, I plan to measure twice: 1) will be a 20Hz to 20kHz multitone signal and 2) will be a limited 80Hz to 20kHz signal. The reason for this is because it is unfair to expect a small bookshelf speaker to extend low in frequency. Applying both will provide a good idea of the limitations if you were to want to run a speaker full range vs using one with a *typical* 80Hz HPF. However, note: the 80Hz signal is a "brick wall" and does not emulate a typical 80Hz HPF slope of 24dB/octave. But... it's close enough.
So, there you go. That's how my testing will be performed. If you have a problem with it, kick rocks. I'm burnt out and ready to move on to something else.
- Erin
This video expands on the previous one because I have now decided on a specific method using Klippel's template (discussed below).
If you saw the previous video where I discussed the MTON and ISC modules used in conjunction, then you don't necessarily have to watch this. However, since I have decided on a measurement method, I made this updated video so everyone can see how I am and will be performing my max SPL testing. In this video, I am measuring at 1 meter using the ground plane technique to improve signal to noise where ground plane increases the SPL by 6dB. However, this does not effect the measurement result in any way other than by simply adding 6dB to the max SPL which I will deduct when presenting the results. If you are wondering why I am not measuring at 2 meters to balance out the 6dB increase, it is, again, to increase the SNR. Moving the mic to 2 meters wouldn't improve accuracy and would just lower the noise floor. Do note, however, for larger (tower) speakers, I will measure as far away as is necessary to be in the "far field".
The measurement follows the IEC 60268-21 Long Term SPL protocol, per Klippel's template, as such:
- Rated maximum sound pressure according IEC 60268-21 §18.4
- Using broadband multi-tone stimulus according §8.4
- Stimulus time = 60 s Excitation time + Preloops according §18.4.1
Each voltage test is 1 minute long (hence, the "Long Term" nomenclature).
The thresholds to determine the maximum SPL are:
- -20dB Distortion relative to the fundamental
- -3dB compression relative to the reference (1V) measurement
Again, I am adhering to a standard. However, I plan to measure twice: 1) will be a 20Hz to 20kHz multitone signal and 2) will be a limited 80Hz to 20kHz signal. The reason for this is because it is unfair to expect a small bookshelf speaker to extend low in frequency. Applying both will provide a good idea of the limitations if you were to want to run a speaker full range vs using one with a *typical* 80Hz HPF. However, note: the 80Hz signal is a "brick wall" and does not emulate a typical 80Hz HPF slope of 24dB/octave. But... it's close enough.
So, there you go. That's how my testing will be performed. If you have a problem with it, kick rocks. I'm burnt out and ready to move on to something else.
- Erin
Awesome! I currently have a pair of the very same Canton Chrono SL 536 here to try. Looking forward to your review! They seem to be decidedly more narrow in directivity than comparable Dalis or Elacs. From my point of view that is a good thing because it matches better with my room.
Cahudson42
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ribosradagast
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OP
- Thread Starter
- #410
haha. Your speakers are famous (in a really niche part of a niche hobby).
OP
- Thread Starter
- #412
This thread is quickly reaching the size and breadth of a subforum
Mostly because I brain-dump all my progress here because I know I'll forget something and need to come back here to remind myself years (or months) down the line.
OP
- Thread Starter
- #413
Oh, speaking of which, I got the Klippel driver test stand set up in my office today. Laser attached. About to test an 8-inch car audio woofer that is crazy expensive and the specs are too good to be true. Either I'm gonna make a lot of enemies or a lot of people happy.
Please post the results on this site too....no enemies here.Oh, speaking of which, I got the Klippel driver test stand set up in my office today. Laser attached. About to test an 8-inch car audio woofer that is crazy expensive and the specs are too good to be true. Either I'm gonna make a lot of enemies or a lot of people happy.
OP
- Thread Starter
- #415
Frickin' sharks with frickin' laser beams... Gearing up for testing the Audio Development W800NEO (car audio product). It's got a lot of praise lately. But many people don't trust the specs which claim 19mm Xmax. I only assume that's peak-to-peak and even if that is 9.5mm one-way linear xmax that's quite a good number for something of this shallow mount nature.
Don't forget to hit the subscribe button and notification button to be notified when I finally release the data/review.
Don't forget to hit the subscribe button and notification button to be notified when I finally release the data/review.
OP
- Thread Starter
- #416
Speaker Polarity Check With A Household Battery
This isn't really new in the realm of DIY'ing speakers. But still, it's something people ask when they are new to the hobby. So I figured making a short video explaining how to use a battery to check polarity might be useful now and again. It would've helped me when I first started.
This isn't really new in the realm of DIY'ing speakers. But still, it's something people ask when they are new to the hobby. So I figured making a short video explaining how to use a battery to check polarity might be useful now and again. It would've helped me when I first started.
OP
- Thread Starter
- #417
When I decided to start testing again early this year my intent was to provide data through my website and use my YouTube page to provide a wrap-up of the reviews and explain the data. I didn’t know how it was going to pan out but I was hopeful it would work. So far, people seem to be quite receptive of this method.
Since most comments I get are in relation to the video reviews, I’m working hard to get my YouTube channel off the ground and gain more visibility in that outlet. There’s been a pretty steep learning curve but I have really been happy with the progress thus far and I am continuing to learn what works and what needs improvement not only in the videos but the subject matter as well.
My hope is that the channel will be a resource for consumers so they understand what they are getting and understand the importance of objective data and how it correlates with subjective listening impressions. Aside from that, however, I want it to be a means of accountability in the community. There are many YouTube “reviewers” who prey on their viewership by providing disingenuous reviews to make a few bucks off Amazon affiliate links or getting free gear in return for a positive review. There are manufacturers who have the means to provide us with specifications so we can make an informed purchase decision but they don’t do that. I want to use my platform to educate the consumer that we can and should expect more from reviewers and manufacturers. Unfortunately, I’m just a little fish in a big pond right now and I can’t achieve these goals without your help.
If there is a video I've created that you think your friends might be interested in, please take the time to share it to your social media page, forums, etc. Or you can share the link to my channel below:
https://www.youtube.com/c/erinsaudiocorner
And let me be clear… as far as monetization goes, I am >2400 view-hours away from generating ad-based revenue. And, for that matter, I believe YT only pays 2 cents per view. So, there are no hopes or crazy dreams of me making this thing a means of income. I mean, enough views might buy me lunch now and again but that’s about it. This isn’t about money. I have a good paying day job that I enjoy. This is about passion. My love for audio. My love for understanding how it works. And my passion for educating us all (myself included; always learning) so we can be better informed. If it weren't, I wouldn't spend the 10+ hours it takes for me to complete a review. That said, if Mcintosh ever offers to send me an amplifier to test out you guys will never hear from me again because I will pack up the amp, my family, dog and swim trunks and fly straight to a coastal country that does not extradite to the US.
So, please share with your friends if you think they'll be interested and let's see if we can't kick off something different in the audio community. Thanks again for your support.
- Erin
Since most comments I get are in relation to the video reviews, I’m working hard to get my YouTube channel off the ground and gain more visibility in that outlet. There’s been a pretty steep learning curve but I have really been happy with the progress thus far and I am continuing to learn what works and what needs improvement not only in the videos but the subject matter as well.
My hope is that the channel will be a resource for consumers so they understand what they are getting and understand the importance of objective data and how it correlates with subjective listening impressions. Aside from that, however, I want it to be a means of accountability in the community. There are many YouTube “reviewers” who prey on their viewership by providing disingenuous reviews to make a few bucks off Amazon affiliate links or getting free gear in return for a positive review. There are manufacturers who have the means to provide us with specifications so we can make an informed purchase decision but they don’t do that. I want to use my platform to educate the consumer that we can and should expect more from reviewers and manufacturers. Unfortunately, I’m just a little fish in a big pond right now and I can’t achieve these goals without your help.
If there is a video I've created that you think your friends might be interested in, please take the time to share it to your social media page, forums, etc. Or you can share the link to my channel below:
https://www.youtube.com/c/erinsaudiocorner
And let me be clear… as far as monetization goes, I am >2400 view-hours away from generating ad-based revenue. And, for that matter, I believe YT only pays 2 cents per view. So, there are no hopes or crazy dreams of me making this thing a means of income. I mean, enough views might buy me lunch now and again but that’s about it. This isn’t about money. I have a good paying day job that I enjoy. This is about passion. My love for audio. My love for understanding how it works. And my passion for educating us all (myself included; always learning) so we can be better informed. If it weren't, I wouldn't spend the 10+ hours it takes for me to complete a review. That said, if Mcintosh ever offers to send me an amplifier to test out you guys will never hear from me again because I will pack up the amp, my family, dog and swim trunks and fly straight to a coastal country that does not extradite to the US.
So, please share with your friends if you think they'll be interested and let's see if we can't kick off something different in the audio community. Thanks again for your support.
- Erin
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Cahudson42
Major Contributor
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Can't help but wonder if the Infinity R152 is worth twice the cost of the Neumi?
Some around here seem to think Infinities are good value when on sale, as they very often are. And right now, a pair of R152 are $199 from Harmon:
https://www.harmanaudio.com/loudspeakers/REFERENCE+152.html
Though they have been as low as $136 (as I remember).
While Amir has reviewed the R162, the R152 has not. Some speculation here has been that, at the expense of bass response, the R152 might actually test better because it should have been easier to match the 5" driver to the tweeter for a smoother response. So, the speculation goes, coupled with a sub, it overall might be 'better'. But who knows?
Would be interesting to find out!
Keep up your great reviews!
Some around here seem to think Infinities are good value when on sale, as they very often are. And right now, a pair of R152 are $199 from Harmon:
https://www.harmanaudio.com/loudspeakers/REFERENCE+152.html
Though they have been as low as $136 (as I remember).
While Amir has reviewed the R162, the R152 has not. Some speculation here has been that, at the expense of bass response, the R152 might actually test better because it should have been easier to match the 5" driver to the tweeter for a smoother response. So, the speculation goes, coupled with a sub, it overall might be 'better'. But who knows?
Would be interesting to find out!
Keep up your great reviews!
OP
- Thread Starter
- #419
I'll look in to the Infinity speakers but I'm not sure I'll have the opportunity to order them right now. I operate my website budget based on contributions and it takes a while to get back to speed to purchase new stuff. I recently had to buy a new amp for testing (needed one for subwoofer excursion tests) and that has tapped me out for a while. If someone has a pair they could send my way then I'd be interested.
OP
- Thread Starter
- #420
For those who haven't seen, I posted a review of the Micca MB42X last night (link). This speaker gets a lot of praise from the YT reviewers... maybe that's because they were good for the money at the time or maybe it's just another example of them trying to make a buck or flat-out not knowing what they are listening for. At any case, my results show a very poor speaker and one I cannot recommend. The Neumi BS5 is much better.
If you don't mind, make sure to share the check out of my video to every facet that you can. I'm trying to shake the review scene up; expose the salesmen who hock crap just so people will buy them through their affiliate links... but I can't do that without help.
If you don't mind, make sure to share the check out of my video to every facet that you can. I'm trying to shake the review scene up; expose the salesmen who hock crap just so people will buy them through their affiliate links... but I can't do that without help.
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