Yes, you are spot on on this one.
I am using a 15” midbass up to 300Hz with 6db/oct crossover. This woofer has a mild peak between 1.5 and 3kHz which isn’t immediately audible with the 6dB/oct crossover but it does blur the midrange a bit. A notch filter cured this but it did not change anything about the tonal balance.
Rms is actually one of the most over looked parameters because it does not show up in any enclosure calculations but to me it is one of the most important parameters in a driver because it is one of the few that says anything about how a driver actually sounds, especially on lower playback levels at home. The other important parameter is the acceleration factor, which is offcoarse closely related. These two combined says something about the “speed” or “lightness” of a driver and how good or bad it will match up with your midrange. The PR170MO is a lovely fast driver, it will sound detached when combined with a sluggish woofer.
Hi
Beyma new 18PW1400Fe/S is the same woofer as the old model, only with new " beyma look" chassis.
Beyma new 18PW1400Fe/S is the same woofer as the old model, only with new " beyma look" chassis.
Isn't it just easier to check out frequency response? If there wasn't enough "speed" or the Rms was too much the amplitude response would show it? I mean matching to mid driver is also by amplitude response, use different / bigger / more drivers to match sensitivity of mid, and tune the crossover.
No not always, it’s not a matter of sensitivity. If you have for instance a heavy cone with high loss surrounds and high driving force the frequency response will be as extended as a driver with less losses but it will sound very different.
Even if both were low passed the same? The parameters indicate there is difference in the natural roll of of the drivers and they would sound very different without crossovers in place, but is there any difference if they were in same application with same frequency response?
I can believe that in practice, say for example with exactly same second order electrical low pass filter applied to both they would both still have enough highs that there might be audible difference. However if the slopes were EQ:d to be same by adjusting the filters per driver, would there still be difference?
Its getting theoretical so perhaps no point to continue. I just kind of caught on the idea that Rms would indicate sound quality, while it might for exactly specific application I cannot believe it could be magic number that would rank some drivers above others for all applications so wanted some more text around the idea. While I believe you have heard difference I'm not buying the explanation without more context, perhaps you compared two drivers in same speaker, with same box and same crossover? that would be believable. Without context I could argue for example, that swapping for bigger driver with similar Rms would sound even better in bass duty below mid woofer.
I can believe that in practice, say for example with exactly same second order electrical low pass filter applied to both they would both still have enough highs that there might be audible difference. However if the slopes were EQ:d to be same by adjusting the filters per driver, would there still be difference?
Its getting theoretical so perhaps no point to continue. I just kind of caught on the idea that Rms would indicate sound quality, while it might for exactly specific application I cannot believe it could be magic number that would rank some drivers above others for all applications so wanted some more text around the idea. While I believe you have heard difference I'm not buying the explanation without more context, perhaps you compared two drivers in same speaker, with same box and same crossover? that would be believable. Without context I could argue for example, that swapping for bigger driver with similar Rms would sound even better in bass duty below mid woofer.
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Rms does not indicate sound quality, it's not that a driver with low Rms automatically sounds any better but it is a valuable indication of how it will sound which is an important factor for midrange matching, in other words, to get the sum of the parts right. Low Rms does indicate that a driver will sound more detailed on very low listening levels though, a high Rms driver needs some juice to open up. Low Rms drivers are less suitable for PA use, they tend to lose control easier on high playback levels. This is all from practical experience with many woofers and midrange drivers both for home and PA use. . Both ways you can get very good results but a mismatch will sound just like that, a mismatch. The OP is using the Audax PR170MO, a driver I know very well and it is a lovely driver which needs a woofer with low losses to get the best combination. Since the OP wants to use a 6dB/oct crossover the behavior of the woofer a decade higher on up becomes an important factor in how the total loudspeaker will sound.
Ah, is the case then trying to match the mechanical parts between woofer and mid so that when they both have similar mechanical properties the "match" is better? Thinking of it for second: by necessity they (bass and mid) would have to be exactly same driver, same size and all, for best match. If the bass woofer is bigger it would need to be lighter so less powerful motor and very different suspension to match a smaller midrange mechanical properties? Meaning that all we want from bass driver is big cone (for greater volume displacement) but otherwise similar properties as mid driver? This ideology doesn't carry to two way speakers for example so this is something three+ way speakers, I see. Perhaps using for example five exactly same driver, one for mid and four for bass? Just gauging the context here more. Quadrupling cone area would have them all bass drivers at exactly same excursion with exactly same physical properties one octave lower than the single mid driver.
I cannot imagine how this plays out like you say. Again I believe you have had experiences and heard differences just interested how you think about it. Here is my understanding and logic: difference between low and high output level playback for any transducer is that the high level output would have more non-linear distortion to it and show differences of the surround and cone mechanical properties as well as differences in motor between any two drivers (this would also mean that all TS parameters are involved in differences.) Why would low level playback be different with different surround properties as its at the most linear region of the woofer after all? I mean any woofer I've checked gets more nonlinear the more there is excursion, the further the cone is from rest position. This would mean that more juice would just bring differences in distortion out to audibility. If the most linear output of woofers, low level output, would be equalized for both woofers to be the same then their non linear behavior would differ instead, especially high level output. The other woofer might need more juice just because its less sensitive so thats true, but it would be just amplitude difference in general. Amplitude or (high level) distortion difference with same juice, involving all TS parameters. Whats your logic for this?
edit. Its interesting but perhaps bit off topic so I'll leave it here 🙂 carry on
I cannot imagine how this plays out like you say. Again I believe you have had experiences and heard differences just interested how you think about it. Here is my understanding and logic: difference between low and high output level playback for any transducer is that the high level output would have more non-linear distortion to it and show differences of the surround and cone mechanical properties as well as differences in motor between any two drivers (this would also mean that all TS parameters are involved in differences.) Why would low level playback be different with different surround properties as its at the most linear region of the woofer after all? I mean any woofer I've checked gets more nonlinear the more there is excursion, the further the cone is from rest position. This would mean that more juice would just bring differences in distortion out to audibility. If the most linear output of woofers, low level output, would be equalized for both woofers to be the same then their non linear behavior would differ instead, especially high level output. The other woofer might need more juice just because its less sensitive so thats true, but it would be just amplitude difference in general. Amplitude or (high level) distortion difference with same juice, involving all TS parameters. Whats your logic for this?
edit. Its interesting but perhaps bit off topic so I'll leave it here 🙂 carry on
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Again, it is not about sensitivity. A high mechanical loss woofer can have the same sensitivity as one with low mechanical loss. It’s about the resistance to get going. Think of it as roadbike tires. Some start rolling almost instantly others take some effort to get going. With loudspeakers it’s the same. High mechanical loss means that it takes more energy to initialise any movement. At very low, as in late evening listening this makes a tremendous difference. A high loss woofers combined with a very low loss midrange subjectively does not produce any low end on whisper volumes. Anyways, in practice this perceived difference always turned out to be the case, each and every time. At party level it’s another story.
If so, then there must be a difference in measurements, e.g. 1w/1m - the same graph, 0,1w/m - one woofer became quieter than other?
Yes it would, acceleration of cone is what makes the sound pressure, so if there is difference in acceleration between two drivers they have different frequency response. Conversely, if they have same frequency response they have same acceleration and "speed" so its not the explanation for the phenomenon I think.
Trusting you have heard difference then here might be something plausible instead, that makes sense to me, not sure if it is this either:
If two systems were equalized for target response at "high" playback level, the other one with weaker woofer that works its limit with compression set in and possible harmonic distortion giving impression of bass end up with different settings than the other system with more capable woofer not compressing or not having as much distortion. This could translate to the low level listening so that the more capable driver sounds quieter simply because it didn't compress while balancing the system. Balance them low level and they sound the same from low level up to where the weaker one gives up and starts to deviate.
Well, anyway I have no explanation for it, just thinking about it. Hearing system is not linear and perception of low frequencies at low listening level is very different than high listening level and my intuition says it has something to do with reports like this.
Trusting you have heard difference then here might be something plausible instead, that makes sense to me, not sure if it is this either:
If two systems were equalized for target response at "high" playback level, the other one with weaker woofer that works its limit with compression set in and possible harmonic distortion giving impression of bass end up with different settings than the other system with more capable woofer not compressing or not having as much distortion. This could translate to the low level listening so that the more capable driver sounds quieter simply because it didn't compress while balancing the system. Balance them low level and they sound the same from low level up to where the weaker one gives up and starts to deviate.
Well, anyway I have no explanation for it, just thinking about it. Hearing system is not linear and perception of low frequencies at low listening level is very different than high listening level and my intuition says it has something to do with reports like this.
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It was a rhetorical question, otherwise, we would have seen many such measurements. 🙂
It seemed to me that the issue of playing at a low volume is more to amplifiers, for example, a different level of noise on low power. But if there is such a subjective difference on one amplifier with speakers with similar properties (not passive speakers with crossovers, for example)... Distortion might be the answer, but there is hardly any noticeable distortion at low volumes, and they are deep under the noise floor?
@tmuikku: I don't know if this would be of any help regarding this question. But I had once asked Kimmosto about how to identify drivers with good dynamics.. 🙂
This was his answer.
https://www.diyaudio.com/community/threads/vituixcad.307910/post-6948755
Especially, this part of his reply may have something to do with Rms:
" Identifying dynamic drivers without measurements is partly guessing. Drivers with high efficiency produce less heat per Pascal so relative thermal compression should be low if motor has also proper ventilation. High efficiency is produced with large and light enough cone, strong motor and low mechanical and electrical losses. High maximum SPL requires also some excursion capacity though cone area or possible horn compensates that."
This was his answer.
https://www.diyaudio.com/community/threads/vituixcad.307910/post-6948755
Especially, this part of his reply may have something to do with Rms:
" Identifying dynamic drivers without measurements is partly guessing. Drivers with high efficiency produce less heat per Pascal so relative thermal compression should be low if motor has also proper ventilation. High efficiency is produced with large and light enough cone, strong motor and low mechanical and electrical losses. High maximum SPL requires also some excursion capacity though cone area or possible horn compensates that."
No, it does not measure quieter but the high loss woofers sound aplomb with a thick curtain in front of them while the low loss woofers sound more vivid. This is my practical experience amongst 20+ woofers and the difference between low loss and high loss woofers was always there and always in about the same way. Ofcosrse it is not the only parameter that makes to look at and it says nothing about absolute quality but it is an important indicator of low level performance for me, again, just from experience in practice
Hi, thanks for the link vineethkumar! for sure, drivers have different capabilities and sound, but its at top of the travel not low level I think?
I guess side by side listening test outside with equalized system would reveal difference, but not sure if it means anything for anyone. If Rms is good indicator for good sound then it probably is, if its 4x 18" drivers for another person then thats it as well Systems could be very different but both would probably enjoy them maximally because they have impression its better, for what ever the reason.
Yes its hard to say what makes a difference, could be many things simultaneously. For example, move your speaker left and sound of bass is different than moving it right 🙂 Just trying to get whats the context that would explain differences in low level listening. It could be the Rms, or some other property that happened to coexists like overall balance of the systems, or just the listening level. Like kimmosto says behind the link its not too hard to poop out small woofers for example, some could compress at very casual listening levels already, very long wavelengths require a lot of volume displacement. For example 5" fullrange drivers I had sounded mighty nice, except I couldn"t get them loud enough, they would just compress when there was some bass in the content. By loud I mean comfortably loud, not loud loud.
I guess side by side listening test outside with equalized system would reveal difference, but not sure if it means anything for anyone. If Rms is good indicator for good sound then it probably is, if its 4x 18" drivers for another person then thats it as well Systems could be very different but both would probably enjoy them maximally because they have impression its better, for what ever the reason.
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0,1 watt is allready pretty loud. It’s what happens in the first miliwatt that is interesting.
I meant scaling itself, not absolute numbers, of course, can be measured in milliwatts.
I do not reject the idea that Rms has such influence (although I did not notice a similar pattern with the speakers that I had). But I am sure that what we hear must be measurable, otherwise it is psychoacoustics and can hardly be tied to the speaker's parameters.
Whatever it is, my speakers with 18fh500 play beautifull at night volumes, I often listen to music when my wife sleeps in the next room. At least better than all the other speakers I've had. 🙂 (With the same wife 😀)
^^Yeah my speaker with 15" also plays better than any system I've had before, which all were better than those before, but I've only gone up in size not sideways with parameters so cant say 😀 as its self made its best ever, right? 🙂
Chris661 posted measurements of low level sound, but couldn't find them quickly. Here is another post of his explaining it though https://www.diyaudio.com/community/threads/the-significance-of-high-qms.120505/post-6737488
Chris661 posted measurements of low level sound, but couldn't find them quickly. Here is another post of his explaining it though https://www.diyaudio.com/community/threads/the-significance-of-high-qms.120505/post-6737488
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Thread linked above has texts like this https://www.diyaudio.com/community/threads/the-significance-of-high-qms.120505/post-1475392
Which suggests that one difference between low /high level sound, perhaps from surround, is due to heat, parameters and priperties changing.
Which suggests that one difference between low /high level sound, perhaps from surround, is due to heat, parameters and priperties changing.