Ladies and gents,
I have a pair of Markaudio Alpair 7P drivers. According to those who know their stuff, they need a long break-in time (200 hours or thereabouts) before they start to sound like they should, just like many other makes and types. For some, it is not a problem and all part of the FR "sports", to others (like me) it is a minor nuisance, but I can also understand that it may be a major nuisance or even a showstopper for entering the FR game. I quote myself (from here):
The above quote should give an idea of what I am after. With this thread I would like to achieve the following:
As I understand it, extended range drivers all depend on a transition from pistonic movement in the LF region, to partial vibrations of the cone and whizzer (if fitted) at higher frequencies. This means that there is either a soft element in the system acting as a mechanical crossover, or that wave propagation through the cone contributes to a major deal of what we hear from them. Or... (fill in the blanks). I think that would be a good starting point for the investigation: first to get to know which phenomena are at play in the different FR driver families. From that point on, we could work along an agenda:
I am aware of the sensitivities that this subject will inevitably bring up. So here's my request to all of you: stick to the topic and the agenda, and only post when you have an answer that contributes to answering the listed questions and advancing the understanding of the reasons why. Otherwise, this thread will not result in anything useful. Although I can not participate and monitor this thread 24 hours a day (in fact, I will hit the sack in a few minutes), I will guard it for staying on-topic, and request the deletion of off-topic, offensive or otherwise inappropriate posts. If things derail, I will request closure of the topic. Moderators might also want to keep an eye out, and be proactive.
To anyone: please chime in if and only if you care about the subject.
I have a pair of Markaudio Alpair 7P drivers. According to those who know their stuff, they need a long break-in time (200 hours or thereabouts) before they start to sound like they should, just like many other makes and types. For some, it is not a problem and all part of the FR "sports", to others (like me) it is a minor nuisance, but I can also understand that it may be a major nuisance or even a showstopper for entering the FR game. I quote myself (from here):
The above quote should give an idea of what I am after. With this thread I would like to achieve the following:
- I want to know if it is possible to accelerate the break-in process of full range drivers that are known to require a long break-in period in normal use
- If yes: I would like to come to a "recipe" for such an accelerated break-in, preferably tailored to each driver family, based on an understanding of the phenomena that contribute to break-in
- If no: I want to know why not
As I understand it, extended range drivers all depend on a transition from pistonic movement in the LF region, to partial vibrations of the cone and whizzer (if fitted) at higher frequencies. This means that there is either a soft element in the system acting as a mechanical crossover, or that wave propagation through the cone contributes to a major deal of what we hear from them. Or... (fill in the blanks). I think that would be a good starting point for the investigation: first to get to know which phenomena are at play in the different FR driver families. From that point on, we could work along an agenda:
- Investigate the sound emission mechanisms in a FR driver
- Investigate how material properties affect these mechanisms
- Investigate how these material properties change during use
- Investigate how to accelerate the initial aging/settling of the materials without doing damage to other parts of the driver
- Write up some recipes if at all possible
I am aware of the sensitivities that this subject will inevitably bring up. So here's my request to all of you: stick to the topic and the agenda, and only post when you have an answer that contributes to answering the listed questions and advancing the understanding of the reasons why. Otherwise, this thread will not result in anything useful. Although I can not participate and monitor this thread 24 hours a day (in fact, I will hit the sack in a few minutes), I will guard it for staying on-topic, and request the deletion of off-topic, offensive or otherwise inappropriate posts. If things derail, I will request closure of the topic. Moderators might also want to keep an eye out, and be proactive.
To anyone: please chime in if and only if you care about the subject.
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Of all the drivers that I have tested, the A7.3 is the only one I spent time breaking in because of the manufacturer's recommendation and the sensitivities surrounding posting anything measured from a MA driver. From a frequency response standpoint, I have not been able to see any difference in the FR curve. I tested them new, at 24hrs, 36hrs, 80hrs. They are still running wrapped in a blanket in a plastic ice cooler to keep the noise emission down. I agree, 200hrs is a long time - that is over 8 days nonstop. The bass extension will probably have some improvement as the suspension will get softer and fs will probably fall. I am using them above 200Hz as a FAST driver so not sure if any benefits will be coming my way.
A few years ago, I purchased a new Ford Transit van. Electronic diesel injection.
I complained of poor performance with lag accelerating and was told by our Ford Main Dealership, that the Electronics will learn or break in over a period of time.
What actually happens is the driver gets use to the performance over a period of time.
Surely this is the same thing that you are talking about? The driver stays the same or is stretched beyond its design and the listener gets use to it!
I complained of poor performance with lag accelerating and was told by our Ford Main Dealership, that the Electronics will learn or break in over a period of time.
What actually happens is the driver gets use to the performance over a period of time.
Surely this is the same thing that you are talking about? The driver stays the same or is stretched beyond its design and the listener gets use to it!
As not all "FR" drivers - even those from the same manufacturer- will have the same mechanical / materials properties, it may take far longer to reach consensus on the items on your second bullet pointed list, than to just follow any particular manufacturer's recommended procedures for each model
I care about the subject in the sense that I think I've experienced the effects of break-in, and moreover have seen these types of "well intentioned" threads devolve into exactly the rancorous noise you're concerned about.
Not just because we've worked closely for over 15yrs, and we certainly don't agree on everything, I'd be inclined to accepting what Dave said in the other thread - sometimes it is what it is.
I care about the subject in the sense that I think I've experienced the effects of break-in, and moreover have seen these types of "well intentioned" threads devolve into exactly the rancorous noise you're concerned about.
Not just because we've worked closely for over 15yrs, and we certainly don't agree on everything, I'd be inclined to accepting what Dave said in the other thread - sometimes it is what it is.
There is no law that says you cannot listen to a set of drivers until they are completely broken in. You can start listening to them from the moment you take them out of the box!
Drivers that have low moving mass and thin cones -- MA, Fostex FE series, Lowther for a few examples -- sound rather harsh straight out of the box. The harshness goes away after a (unspecified) while. You can clearly demonstrate this by comparing a new driver to one with some time on it. Does it really take hundreds of hours? Who knows. That would take a stack of drivers with different times on them to do the comparison, and the chances that this would ever be done ABX is nil. But to suggest that you cannot listen to a new pair of drivers until they have 200hrs on them is ludicrous.
Put your speakers together and start using them.
Bob
Drivers that have low moving mass and thin cones -- MA, Fostex FE series, Lowther for a few examples -- sound rather harsh straight out of the box. The harshness goes away after a (unspecified) while. You can clearly demonstrate this by comparing a new driver to one with some time on it. Does it really take hundreds of hours? Who knows. That would take a stack of drivers with different times on them to do the comparison, and the chances that this would ever be done ABX is nil. But to suggest that you cannot listen to a new pair of drivers until they have 200hrs on them is ludicrous.
Put your speakers together and start using them.
Bob
The particular pair under discussion had at least 300 hrs on them before they got off the break-in bench and another 400 hrs before they went off to Chris to go into the MTM. I don't know how many hours Chris put on them but i expect i got them back with over 1000 hrs on them.
Most drivers i do are pretty goodcoming off the break-in bench.
dave
One only needs to take a speaker that is broken in (assuming it needs it) right next to a freshly built pair to know that this is not the case. The drivers do indeed break-in.
dave
Gents,
Thanks for chiming in. As I may wrap up the first day (night for me) of discussion, I am pleased to see that it has yet remained civil. Bob, Chris and Dave have had a lot of these drivers in their hands, and can directly compare newly out of the box ones with ones that have already aged, often in identical systems. They report that they are different. This adds, at least anecdotally, sufficient plausibility to the break-in phenomenon to continue to ponder what lies beneath it. So please, let the "is break-in real?" question rest from now on.
Also, I don't want to discuss if a break-in period is problematic or not. If your situation and/or work flow allows for having a good break-in period without impeding progress, then that's fine, and thanks for the tips. But it all depends on one's personal situation and attitude. For me, I need to cook up a crossover, and it would be good to do that only when the drivers are settled. Currently, I don't like the sound they produce, so I prefer not to hear them while break-in progresses. Nowhere did I say that they can't or shouldn't be listened to. Again, it's personal preference.
Both XRK and I have drivers in a break-in box in order for them to undergo the manufacturer's recommended break-in procedure. These boxes are both out of ear's reach, so we can compare the before and after sonic verdicts and responses without our ears getting used to the driver's special traits. We'll see what comes out of this. In my case, the reported break in requirement has already exceeded 300 hours and is moving on towards 1000.
That only confirms that my desire to accelerate the process is reasonable. IMHO of course...
So for the remainder of this discussion, let's try and keep focused on the agenda from post #1.
Thanks for chiming in. As I may wrap up the first day (night for me) of discussion, I am pleased to see that it has yet remained civil. Bob, Chris and Dave have had a lot of these drivers in their hands, and can directly compare newly out of the box ones with ones that have already aged, often in identical systems. They report that they are different. This adds, at least anecdotally, sufficient plausibility to the break-in phenomenon to continue to ponder what lies beneath it. So please, let the "is break-in real?" question rest from now on.
Also, I don't want to discuss if a break-in period is problematic or not. If your situation and/or work flow allows for having a good break-in period without impeding progress, then that's fine, and thanks for the tips. But it all depends on one's personal situation and attitude. For me, I need to cook up a crossover, and it would be good to do that only when the drivers are settled. Currently, I don't like the sound they produce, so I prefer not to hear them while break-in progresses. Nowhere did I say that they can't or shouldn't be listened to. Again, it's personal preference.
Both XRK and I have drivers in a break-in box in order for them to undergo the manufacturer's recommended break-in procedure. These boxes are both out of ear's reach, so we can compare the before and after sonic verdicts and responses without our ears getting used to the driver's special traits. We'll see what comes out of this. In my case, the reported break in requirement has already exceeded 300 hours and is moving on towards 1000.
That only confirms that my desire to accelerate the process is reasonable. IMHO of course...So for the remainder of this discussion, let's try and keep focused on the agenda from post #1.
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Now some hypotheses from my side. I hope this will get a good discussion started.
I would like to categorize FR drivers in three categories, depending on membrane behavior, being:
1
Those drivers that rely on traveling waves through the membrane for sound emission. Not only MA drivers do that, but also BMRs and the Manger Schallwandler (MSW). The similarities between the three are surprising! The speed at which a transverse wave propagates through the membrane determines the angle at which the sound is transmitted from it. The faster the wave travels, the more perpendicular to the surface the outgoing wave will go. BMRs and MSWs rely on bending waves predominantly, but a non-flat membrane will also have hoop stresses that act as a restoring force.
2
Those drivers that rely on a mechanical filter between voice coil/whizzer and cone. This is a classical mass-and-damped-spring system acting as a low pass filter between cone and VC. The result is a mechanical two-way speaker, that (hopefully) prevents the large cone from working beyond its break-up limit. I do not know of a current driver that exploits this mechanism in its pure form, but some vintage drivers that are like this do exist. Does anyone know examples?
3
Drivers that rely on the cone to damp propagating vibrations through the cone at a controlled rate, by making (part of) the cone deliberately flexible in order to achieve a mechanical filter. It can be seen as a refinement of #2, which result in the net emitting area getting smaller as frequency increases. I suspect that the Vifa units and many other more mainstream drivers are like this.
Case #1 relies on the cone's bending stiffness, and in case of a non-flat cone, also on its elasticity, for the restoring force of a traveling wave. The exact cone material and layer composition determine these properties. The mass of the cone does (hopefully) not change significantly during the life of the driver, so the bending/stretching properties and losses of wave propagation are the properties that may evolve.
Case #2 relies on the properties of the mechanical filter components, which are predominantly the cone's mass and the springy material's elasticity and damping properties. While again, I do not think that the cone will change in mass significantly, the springy stuff might evolve.
Case #3 relies on the ability of the cone to damp a wave coming from the voice coil before it reaches the edge. As in #1, restoring force, mass and damping determine the exact behavior, but now, damping is such that post break-up sound emission by the cone is suppressed to some degree. I expect the properties to evolve to be the same as in #1, but their impact to be less.
Please let me know if there are omissions. I think I have covered the majority of drivers concerned.
I would like to categorize FR drivers in three categories, depending on membrane behavior, being:
1
Those drivers that rely on traveling waves through the membrane for sound emission. Not only MA drivers do that, but also BMRs and the Manger Schallwandler (MSW). The similarities between the three are surprising! The speed at which a transverse wave propagates through the membrane determines the angle at which the sound is transmitted from it. The faster the wave travels, the more perpendicular to the surface the outgoing wave will go. BMRs and MSWs rely on bending waves predominantly, but a non-flat membrane will also have hoop stresses that act as a restoring force.
2
Those drivers that rely on a mechanical filter between voice coil/whizzer and cone. This is a classical mass-and-damped-spring system acting as a low pass filter between cone and VC. The result is a mechanical two-way speaker, that (hopefully) prevents the large cone from working beyond its break-up limit. I do not know of a current driver that exploits this mechanism in its pure form, but some vintage drivers that are like this do exist. Does anyone know examples?
3
Drivers that rely on the cone to damp propagating vibrations through the cone at a controlled rate, by making (part of) the cone deliberately flexible in order to achieve a mechanical filter. It can be seen as a refinement of #2, which result in the net emitting area getting smaller as frequency increases. I suspect that the Vifa units and many other more mainstream drivers are like this.
Case #1 relies on the cone's bending stiffness, and in case of a non-flat cone, also on its elasticity, for the restoring force of a traveling wave. The exact cone material and layer composition determine these properties. The mass of the cone does (hopefully) not change significantly during the life of the driver, so the bending/stretching properties and losses of wave propagation are the properties that may evolve.
Case #2 relies on the properties of the mechanical filter components, which are predominantly the cone's mass and the springy material's elasticity and damping properties. While again, I do not think that the cone will change in mass significantly, the springy stuff might evolve.
Case #3 relies on the ability of the cone to damp a wave coming from the voice coil before it reaches the edge. As in #1, restoring force, mass and damping determine the exact behavior, but now, damping is such that post break-up sound emission by the cone is suppressed to some degree. I expect the properties to evolve to be the same as in #1, but their impact to be less.
Please let me know if there are omissions. I think I have covered the majority of drivers concerned.
In case #1, it becomes immediately clear why, for example, MA warns against using signals from a generator such as sines, stepped sines or MLS signals for the purpose of break in. Any wave hitting the cone's edge will reflect from it, causing a zone with standing waves, which means that the elastic properties of the cone material are only stressed in certain locations, depending on frequency. Using a prolonged sine signal with such a cone will cause the break in effect to concentrate in one area, causing excessive aging there, while not working out the cone in other areas. Only signals that contain a smooth frequency spectrum will ensure that the entire cone area is representatively stressed to its intended use, and no areas are "forgotten". Real noise (not an MLS signal, which is periodic, or a quasi random number sequence fed to a DAC) and music from varied sources fit this requirement, and so we arrive at the recommendation to just let them play and be patient.
But that takes too long for my taste. If I am not mistaken, the effect described above only happens with frequencies above the break-up frequency. Below the break-up frequency, the cone behaves more or less like a piston. Music has most of its energy below the break-up frequency of the cone, and thus will age the spider/surround with a lot more force, while the aging process of the cone is trailing behind. I think that the spider and surround need no more than a few hours of break-in, and are "there" much quicker than the cone will be.
That's why I would like to propose to break in drivers from family #1 with music passed through a first order high-pass filter, with the corner frequency set at, or slightly below, the lowest break-up frequency. In this way, the cone can be exercised to much greater effect, without placing undue stress on the suspension (and thus on the cone's edge). In all drivers from this family (including the MSW), the lowest break-up is easy to spot in the impedance plot.
Any comments? If I am wrong, it is of course OK to tell me. But if you do, please take the time to properly explain why.
If you have additional ideas on any of the driver families, please share!
But that takes too long for my taste. If I am not mistaken, the effect described above only happens with frequencies above the break-up frequency. Below the break-up frequency, the cone behaves more or less like a piston. Music has most of its energy below the break-up frequency of the cone, and thus will age the spider/surround with a lot more force, while the aging process of the cone is trailing behind. I think that the spider and surround need no more than a few hours of break-in, and are "there" much quicker than the cone will be.
That's why I would like to propose to break in drivers from family #1 with music passed through a first order high-pass filter, with the corner frequency set at, or slightly below, the lowest break-up frequency. In this way, the cone can be exercised to much greater effect, without placing undue stress on the suspension (and thus on the cone's edge). In all drivers from this family (including the MSW), the lowest break-up is easy to spot in the impedance plot.
Any comments? If I am wrong, it is of course OK to tell me. But if you do, please take the time to properly explain why.
If you have additional ideas on any of the driver families, please share!
The designer of the spiders on the MA drivers (and also of the FExx6e Fostex) has said that he has designed spiders that take 1500 hrs to break in, so i would say that you will find cases where a couple hrs won't do…
dave
Hi
I'm a no expert on topic but I can suggest another mechanism that may be responsible for the break-in changes.
I have always assumed it was not the cone itself that needs breaking in but the spider. In an ideal speaker, the force responsible for restoring the cone to its normal central position should be directly proportional to the displacement, i.e. linear. If the forces are not directly proportional, then the response of the cone to the voice-coil current will also be non-linear - i.e. it will produce distortion. This effect will be apparent only at low frequencies - within an octave or two of fo, where the mechanical impedance of the cone is dominated by the compliance rather than the inertial mass.
I don't know how a typical spider is constructed, but they've always looked to me like some sort of impregnated fabric,that probably has a non-linear flex, especially straight out of the box. As the spider is flexes with time it softens and becomes more linear.
A test for this hypothesis is that the resonant frequency of the driver should fall slightly as it breaks in, and the low frequency distortion should also fall as it breaks in. I do not expect a change in the flatness of the frequency response.
I expect that given enough time, the driver will break in no matter what the excitation signal, but some types of signal and exposure may reduce/minimise the time taken to break in.
regards
Rod
I'm a no expert on topic but I can suggest another mechanism that may be responsible for the break-in changes.
I have always assumed it was not the cone itself that needs breaking in but the spider. In an ideal speaker, the force responsible for restoring the cone to its normal central position should be directly proportional to the displacement, i.e. linear. If the forces are not directly proportional, then the response of the cone to the voice-coil current will also be non-linear - i.e. it will produce distortion. This effect will be apparent only at low frequencies - within an octave or two of fo, where the mechanical impedance of the cone is dominated by the compliance rather than the inertial mass.
I don't know how a typical spider is constructed, but they've always looked to me like some sort of impregnated fabric,that probably has a non-linear flex, especially straight out of the box. As the spider is flexes with time it softens and becomes more linear.
A test for this hypothesis is that the resonant frequency of the driver should fall slightly as it breaks in, and the low frequency distortion should also fall as it breaks in. I do not expect a change in the flatness of the frequency response.
I expect that given enough time, the driver will break in no matter what the excitation signal, but some types of signal and exposure may reduce/minimise the time taken to break in.
regards
Rod
Does he lurk here, or can he be reached somehow?
@ Golfnut: I think you raise some valid points about the spider. But break-in also covers midrange and treble, and for those frequency ranges, I think that the cone behavior dominates the performance of the driver, while the spider's task is limited to not interfering. This demand may not be trivial to realize though.
Some spiders/surrounds never learn. I have a well broken in older Peerless driver, which shows a resonance frequency that lowers with increasing drive level. This suggests that the restoring force exerted by the suspension is not directly proportional to cone excursion, but exhibits a fractional power proportionality (i.e. less progressive than directly proportional) and/or some hysteresis. At frequencies >> Fs that has no impact, but the driver does suffer from a perceived loss of bass at lower drive levels. I heard this before I found out why.
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