Does any German reading people happen to have huperlinks or digital photos of Timmermanns Rms and low power distortion stuff? It's really hard to find with search engine outside of germany and without proper search words. It would really save ton of time, finding the magazines and then translating them one by one to find the stuff is a lot of work. Thanks!
Hello tmuikku, do not get your hopes up too high: Timmerman has been stating this frequently over the years, but to my best of knowledge there never has been any comprehensive controlled comparative testing proving his point. Until I ended my subscription to HH around 2010, just statements were all there was:no evidence whatsoever.
Hi Boden,
yeah, that's what I'm afraid of so trying to get bottom of the bucket. The 'wakeup' effect ICG mentioned here seems to popup in forums every now and then. I think it's likely valid observation perceptually although the explanation doesn't make any sense to me at this point before more personal experience.
For example my pro woofers 15fh520 TS parameters measured quite different than what is on the datasheet. I asked about this from the manufacturer and they responded the datasheet spec is after long term use, which makes sense to me: In pro application system is likely driven near it's capacity and it is better the driver spec to fall in place rather than out of, as things warm up. This likely has some audible effect on bass on low power listening (although my drivers have been sounding just fine). But so does equal loudness curves. Heck, could be the other way around, that technically good driver that doesn't have power compression apparently sounds very different on low and high power, because of equal loudness curves. Another driver could compress on higher power compensating for equal loudness curves making it appear better perceptually, although it is technically worse. This could be then thought as if the good driver was bad because it sounds different on low and high power, while the bad driver sounds good on both. This explanation is more logical to me, than somehow having non-linear effects appear on low power which is exactly opposite how other driver non-linearities work, they get worse with more power (excursion).
Anything is fine though, we have to work with the drivers that are available and make best out of, some fit better some worse for any given application. It's just the explanation I'm after so that I could buy correct driver for given application without resorting to black magic, hence chasing down the myths.
yeah, that's what I'm afraid of so trying to get bottom of the bucket. The 'wakeup' effect ICG mentioned here seems to popup in forums every now and then. I think it's likely valid observation perceptually although the explanation doesn't make any sense to me at this point before more personal experience.
For example my pro woofers 15fh520 TS parameters measured quite different than what is on the datasheet. I asked about this from the manufacturer and they responded the datasheet spec is after long term use, which makes sense to me: In pro application system is likely driven near it's capacity and it is better the driver spec to fall in place rather than out of, as things warm up. This likely has some audible effect on bass on low power listening (although my drivers have been sounding just fine). But so does equal loudness curves. Heck, could be the other way around, that technically good driver that doesn't have power compression apparently sounds very different on low and high power, because of equal loudness curves. Another driver could compress on higher power compensating for equal loudness curves making it appear better perceptually, although it is technically worse. This could be then thought as if the good driver was bad because it sounds different on low and high power, while the bad driver sounds good on both. This explanation is more logical to me, than somehow having non-linear effects appear on low power which is exactly opposite how other driver non-linearities work, they get worse with more power (excursion).
Anything is fine though, we have to work with the drivers that are available and make best out of, some fit better some worse for any given application. It's just the explanation I'm after so that I could buy correct driver for given application without resorting to black magic, hence chasing down the myths.
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As I see it, a comprehensive set Klippel of BL vs excursion, Kmx etc. et.c measurements tell us all one should know for all practical purposes. The i.m.o. rest is all smoke and mirrors. But hey, magazines must keep their readers by carefully feeding them "stuff".
@head_unit
It is not best example, but here you have the Dayton UMII-15 in 150l closed box with its original Bl value and then about doubled:
See, between 23Hz and 60Hz, the model with lesser motor force shows more output. Well, because it gets more input.
Based on the constant voltage drive but different impedance, it is not a discussion or opinion:
I worked on this an asked mr. @David McBean to implement constant power curves in the hornresp. And he kind of did already! You can watch constant power responses!
So, here we go, The UMII-15 with Bl 23,1 vs Bl 14,61 simulated by Hornresp at 1Watt. I do not remember anymore, but I guess phase is accounted for, so you are looking at real power, not apparent power. That is ANOTHER HUGE MEGA CAN OF WORMS on top of that, that 95% of people ignore. The different Bl value sims have different scales, so sorry for poor overlay.
1Watt SPL response:
And yes, the upper line is the one with higher Bl.
It is painfully obvious from many sides than Bl adds output (efficiency), and so seeing a case where it takes output, should make you stop, step back and reevaluate what´s happening. Why you get the data you are getting. One piece of data of the two contradictory pieces of data MUST be wrong. This is not fuzzy logic or quantum particle behavior. 🙂 It is mutually exclusive.
Of course this must be accounted for in the design. High Bl high impedance drivers are tough cookies to drive. Once you start exceeding 600V p-p input as I did on RCF LF21N551, you have some mess on your hands. That´s why IPALs are so low impedance.
//Edit: Maintenance, cleanup, grammar and corrections
It´s not always this obvious. Sometimes not only the transfer function magnitude says this, but also SPL (sensitivity) graph shows this too. With higher Bl, it might appear in SPL output with constant voltage, that the driver gives less output. But basically what happens is, that it gets less input, hence the comparison falls apart.
It is not best example, but here you have the Dayton UMII-15 in 150l closed box with its original Bl value and then about doubled:
See, between 23Hz and 60Hz, the model with lesser motor force shows more output. Well, because it gets more input.
Based on the constant voltage drive but different impedance, it is not a discussion or opinion:
This can get much more complicated. I wanted to reduce it down so people would swallow it. Didn´t help.
I worked on this an asked mr. @David McBean to implement constant power curves in the hornresp. And he kind of did already! You can watch constant power responses!
So, here we go, The UMII-15 with Bl 23,1 vs Bl 14,61 simulated by Hornresp at 1Watt. I do not remember anymore, but I guess phase is accounted for, so you are looking at real power, not apparent power. That is ANOTHER HUGE MEGA CAN OF WORMS on top of that, that 95% of people ignore. The different Bl value sims have different scales, so sorry for poor overlay.
1Watt SPL response:
And yes, the upper line is the one with higher Bl.
It is painfully obvious from many sides than Bl adds output (efficiency), and so seeing a case where it takes output, should make you stop, step back and reevaluate what´s happening. Why you get the data you are getting. One piece of data of the two contradictory pieces of data MUST be wrong. This is not fuzzy logic or quantum particle behavior. 🙂 It is mutually exclusive.
Of course this must be accounted for in the design. High Bl high impedance drivers are tough cookies to drive. Once you start exceeding 600V p-p input as I did on RCF LF21N551, you have some mess on your hands. That´s why IPALs are so low impedance.
//Edit: Maintenance, cleanup, grammar and corrections
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Regarding the waking up, This is chasing a chimera. Any aspect can have a part of it, but my bet goes to low sensitivity and thermal compression effects.
It was not mind blowing change, but I felt this with my first higher Bl(at that time) driver. It was used in an a ClassA/RCF Bassbin style box that has only 70l of back volume. B&C Speakers 18NW100. They all called it fast, horn driver.
So you have No serious volume behind the cone, and you have low sensitivity (for bass anyways) driver. That should be a disaster. Some people tried to stop me making the choice back then. When I pulled them out and played, it was okay, but somewhat meh. After about half an hour, these mofos STOMPED at 40Hz. After heatup, the power finally went there, hence the performance went out.
I guess I got used to it, so next time with Bl30, 33, 39 drivers, It didn´t get to me that much. But also I was much better prepared with the amp that was able to deliver enough volts.
It was not mind blowing change, but I felt this with my first higher Bl(at that time) driver. It was used in an a ClassA/RCF Bassbin style box that has only 70l of back volume. B&C Speakers 18NW100. They all called it fast, horn driver.
So you have No serious volume behind the cone, and you have low sensitivity (for bass anyways) driver. That should be a disaster. Some people tried to stop me making the choice back then. When I pulled them out and played, it was okay, but somewhat meh. After about half an hour, these mofos STOMPED at 40Hz. After heatup, the power finally went there, hence the performance went out.
I guess I got used to it, so next time with Bl30, 33, 39 drivers, It didn´t get to me that much. But also I was much better prepared with the amp that was able to deliver enough volts.
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Hurrication was working on a driver with an underhung voice coil on a titanium former, with it's windings "air gapped straight to aluminum heatsink in the motor, so all of the heat transfer is done directly to the windings instead of through the former" driver last year:
https://www.diyaudio.com/community/...handling-of-a-voice-coil.398849/#post-7373895
Anything that can transfer more voice coil heat directly to the outside air, rather than the magnet structure is useful.
Getting the motor's heatsink to transfer it's heat to the outside air in a 1.25 cubic foot box would be an innovation.
I can understand why we probably won't see much more info.
I want to believe in a new motor technology when it is proved to be better.
The Brane Audio Repulse Attract Driver (R.A.D.) is an example of "groundbreaking" new motor technology used in small enclosures:
https://www.diyaudio.com/community/...pel-attract-driver.395631/page-4#post-7632469
Reducing the amount of heat generated, rather than transferring it seems "cool" to me 😎
Art
The Volt use of an external chassis frame as a heat radiating surface is a good concept.
That said, the 18" Volt RV4564 with 12.5mm Xmax (22mm Xlim), a 100mm voice coil and only 750 watt (AES) rating compared to double that for drivers with comparable excursion does not inspire much confidence in it's heat dissipation capabilities.
At any rate, there are many loudspeakers that will work better than the Volt RV4564 in small sealed enclosures where heat build up may be a concern.
That said, the 18" Volt RV4564 with 12.5mm Xmax (22mm Xlim), a 100mm voice coil and only 750 watt (AES) rating compared to double that for drivers with comparable excursion does not inspire much confidence in it's heat dissipation capabilities.
At any rate, there are many loudspeakers that will work better than the Volt RV4564 in small sealed enclosures where heat build up may be a concern.
That is a different design, an older one that has already been purchased by another large company. Not what I am talking about here.
Now you're thinking! Imagine the cooling you would get if the entire motor was outside of the enclosure, and the voice coil was directly exposed to the outside air. 😲 😉
I have listened to the Brane, and it's really good for a little bluetooth speaker. Those things hardly generate any heat at all, just because they run on such a little mount of power. Different game there - efficiency is king in that world. But their tech is highly impractical for use as a large subwoofer.
Does an alloy cone on an alloy former achieve this to an extant ina practical way?
Makes sense to do it that way, but few examples exist.
On the huge side, Powersoft's 30" 20kWatt (peak) M-Force 301P02:
And on the small side, the cute 8" Morel Ip-BMWSub82 with the usual hype:
If rear mounted, the Ip-BMWSub82 is external structure does not protrude (much) from the baffle, a good characteristic for small subs. It would be "cool" if more options like it were available at prices commensurate with performance.
Not holding my breath for that to happen.
It can, aluminum alloy cones certainly transfer heat faster than paper pulp, and won't ignite at Fahrenheit 451, or 233C, which doesn't make as good a book title.
Art
Art, I find the heat thing interesting as something that is also an issue with a marine motor project of mine. I am not up on the technicals so go easy
May I change tack from heat disposal to the reason for the heat being there in the first place? Why is the coil heating, is this I2R loss?
Keeping the small cab in context, additional weight might not be a bad thing as cone weight can be reduced to allow an alloy cone and the weight needed to drive a lower extension engineered closer to the central axis to help with dialling out cone rock (race kart ballast styles)
1 - Would coils made with much thicker wire have less resistance and heat up less for the same current flow?
2 - Silver wire coils? Savings on cone tech with a simple aluminium cone might allow funds for silver wire? A premium pro driver for a small studio mastering sub wouldn't be lolly money and consistent performance at higher outputs for hours long sessions would want a premium price
That gorgeous Mackie of yours with the RCF driver (hey, I asked you if you knew which driver). Any guesstimates how much more that driver would cost if it had silver coils?
They exist: Illusion Audio, Arc Audio have them. Problem is that they aren't are over 12" and they don't have the motor force to drive a big sub in small airspace. 😉
Hi,
so you recognize the phenomenon? Do I understand your text correctly that you do not describe difference with low power / high power but you had high power all the time and difference was between cold and warm driver so equal loudness curves ruled out as the cause? So, when you started playing (loud) the bass wasn't too good at first, but after driver warmed up the sound changed?
I'm asking this because in this thread ICG used low power and high power distinction that makes to the "wake up" effect. If you always had high power and sound still changes the sound is not directly related to power, but to heat build up. I mean that if one listens quiet and loud one after another repeatedly the sound doesn't change with the volume knob but only if heat builds up.
If true, this would make case it is not the equal loudness curves but consequence of heat, that changes the sound. One could make argument that putting a heater inside the box for home use is then equivalent to high power use regarding the "wake up".
Sorry I'm not trying to claim anything here, just trying to reason what all you guys are saying about this phenomenon. Trying to get angle to it.
Well, I am not sure which is which neither. When I heard the waking up around me, it was too general claim. Like, ghe driver doesn't play at low watts, it needs feeding.
How the situation was described to me was rather nonlinear behavior and loudness curves combo.
Now if I think about it, I DO witness this RN with my setup! Sometimes the bass lacks, but when I add up on the volume, the bass goes equal. Or overbearing. That is another case I was not talking previously.
Back to the original one:
I do not stand by the claim strongly, it is opinion and feeling of the situation. The sound got warmer, heftier, after heatup. That's what I believe I was hearing. Might be that and might be nonsense.
How the situation was described to me was rather nonlinear behavior and loudness curves combo.
Now if I think about it, I DO witness this RN with my setup! Sometimes the bass lacks, but when I add up on the volume, the bass goes equal. Or overbearing. That is another case I was not talking previously.
Back to the original one:
I do not stand by the claim strongly, it is opinion and feeling of the situation. The sound got warmer, heftier, after heatup. That's what I believe I was hearing. Might be that and might be nonsense.
I think it's as valid data as any 😀 I'm lacking experience of it so need to ask for it. In general, It's kind of obvious sound would change with increasing heat. But, need to somehow quantify the effect to something in order to be able to avoid it when necessary. Main concern of mine being whether a driver works in home use as well as in party use, or do I need two systems for these two very different SPL scenarios. I'll do DSP presets for both as there are many things different so perhaps it's not too bad. Will see shortly 😀
Perhaps there are multiple effects confused as one. In the end talk like this doesn't come with audio so everyone has to really experience the same thing and discus in situ to have some kind of a concensus. Anyway, interesting phenomenon now that it's relevant personally 🙂
Perhaps there are multiple effects confused as one. In the end talk like this doesn't come with audio so everyone has to really experience the same thing and discus in situ to have some kind of a concensus. Anyway, interesting phenomenon now that it's relevant personally 🙂