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Speaker Break-In and Environmental Measurements

MAB

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Nov 15, 2021
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The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:
  • I hear on various forums that you can facilitate the break-in of your speakers by placing them face to face and wiring one out of phase. Turn the volume up. Walk away. Come back later.
  • Stores sell things to facilitate break-in. I suggest bank accounts are the only thing that's suffering break-in.;)
  • I've been flamed on the usual forums for suggesting that a person should enjoy their new speakers and ignore any audible effects of break-in. I think most of the changes in the first few hours or days of getting new gear is the listener, not the gear. Despite that some people won't listen to their new HiFi until it has been subjected to various break-in procedures, seemingly out of some compulsion.
  • And of course major manufacturers from time to time make a big deal about break-in. According to some, you should expect pretty large differences after break-in. And break-in will take some time. And things will always sound better.
To be clear, I think speaker break-in (aka run-in) is measurable but typically tiny and should typically be ignored. Wear-out is real too, and some of the above practices at high SPL are aging to wear-out, which is different than break-in. The videos of people advocating this are available on YouTube. The culture exists. Kef even mentions this culture:
Speaker break-in and cables. If you want to ignite a war in an internet forum, bring up one of these two topics. We're not going to touch cables in this piece, but you speaker break-in non-believers, prepare for it – speaker break-in is most definitely a thing.
There are two radically opposing schools of thought regarding the need to burn-in, or break-in, new speakers.
First Radical School of Thought: Speaker run-in is an utterly ridiculous idea.
This school of thought basically states that our ears become accustomed to the sound of our new speakers (making them seem to sound better) and that the overall performance of a speaker doesn't change perceptively with use.
Second Radical School of Thought: Speakers are only worthwhile to listen to after several hundred hours of burn-in with a white noise generator and increasing amounts of bass-driven music.
This school of thought believes that speakers must be broken in sufficiently and properly in order for the performance of the speaker to be enjoyable to even the average listener.
As usual, the truth lies somewhere in the middle.
I belong firmly to a school that isn't quite listed in Kef's marketing statement. I know that drivers do change under break-in; I have measured it. The measurements I have taken and seen tell me break-in is tiny, and smaller than a change in room temperature or voice-coil temperature that a speaker will see under normal operation. I have shown this with a few drivers, I did some fairly careful measurements with a Seas W18 metal cone woofer and a JBL 2216Nd paper 15" cone woofer. Both of those drivers showed very small changes with break-in, even after 6 months of use on the JBL. The JBL in particular changed so little, hard to imagine hearing or even being able to measure with a microphone a significant change in system output in a carefully controlled aging experiment. Certainly way below environmental effects like what the thermostat is set at or how hard have the drivers been playing over the past few minutes or hours.

Since the subject came up again, I thought it a good time to revisit this topic with some unused drivers I have lying around.
I have two Peerless 831724 10" woofers and two Audax HP210GO 8" woofers, with synthetic cones. I also have four HiVi B3N metal cone micro-woofers.
1703187774071.png


I am presenting the measurements of these drivers before and after break-in. Each set of drivers was broken-in at ambient room conditions for 6 hours, with a signal I thought was sufficient. I don't quantify 'sufficient', except to say I drove them moderately hard with bass for 3 hours, and 3 more hours with pink noise. I specifically kept them well within their power limits, my goal was not to wear them out. I also explore the impact of moderate temperature changes both due to the break-in stress and due to external heating and cooling.

The heating and cooling is primitive. 10 mins in the refrigerator for cooling. I used a space-heater to elevate the temperatures, measurements were made with the heater off since the airflow has significant impact on the results.

1703192363895.png


Figure 1 shows the results of a break-in and temperature experiment on an Audax woofer. The raw driver was first measured (runs 1 and 2), then put in a refrigerator for 10 mins, then measured again (Runs 3 and 4). The speaker was then broken-in for 6 hours as described above, and measured immediately after while still hot from stress (Run 5). Then I allowed the driver to cool off to get the post-break-in measurements (Runs 6 and 7). The driver was then subjected to heat from a small space-heater (Runs 8-14). The space heater was moved to attempt to increase the heat, which most notably impacted measurement 14. Finally, after cooling off, the driver was remeasured (Run 15).

1703188775146.png


To better summarize the data, the changes in f(s) are normalized to the average of the measurements made right out of the box, which is 44.0 Hz.
1703191456941.png


Break-in changed f(s) changed by 1.8%, this is small. Not much bigger compared to putting the driver in the refrigerator for 10 mins (1.2%). Not much bigger than the heat from the application of stress (1.5%). And smaller than the impact of the space heater. Perhaps I could have measured the speaker in the refrigerator while cooling it to get better temperature granularity. And longer cool-down to explore larger fluctuations. And applied more heat, perhaps heat to the motor with a hot plate. And correlated it to actual temperatures of the driver components. But despite this rough approach, I think this is a good approximation of some of the changes that will occur in a home.

In summary, this Audax woofer break-in data shows modest changes in f(s) and other parameters. These changes are smaller than environmental effects. It's hard to imagine the measured break-in changes are audible even under ideal conditions.

Figure 3 shows a simple break-in experiment on a pair of Peerless 10" drivers.
1703192934168.png


The Peerless drivers show large mismatch in parameters between the two. They show individually 2.6% and 3.2% change in f(s) post break-in. Run 3 suggests that the impact of the heat due to the break-in stress is larger than the changes due to break-in. And the trends from Run 3 to Run 8 suggest that it took hours for the driver to dissipate the heat from the stress and come back to equilibrium with the room.

The Peerless 10" woofers are more sensitive to the temperature effects of break-in than the actual physical changes due to break-in, the evidence is the f(s) trend from run 3 to run 8 as the driver cools back down to room T. Speaker to speaker matching is also larger than break-in effect. Unclear if the mismatch is due to defect or normal run to run variation. It's difficult to believe these small differences are audible.

Figure 4 shows the results of break-in on four HiVi B3N micro-speakers:
1703198452050.png


These drivers' f(s) changes 10% from new. This is quite large compared to all previous drivers I have measured.
I don't know how long it took for the drivers to change. I did confirm that further stress causes no additional change.

This small HiVi speaker does change appreciably with stress. All four units behave the same with stress, despite the fact one driver has outlier L(e). This is the lone observation of a significant break-in effect. Perhaps the size of the driver can allow large changes to occur compared to a larger driver. Perhaps these HiVi drivers are an outlier for break-in.

This is the first time I have seen dramatic changes with stress like this. That being said, I have only made ad-hoc observations and half-dozen concerted measurement attempts to see how big the break-in effect is. But this is the only driver I have ever found to have significant change. Do metal cone drivers break in more? The JBL 15" paper cone woofer I refenced above changed from new only 1-2% over 6 months of heavy use.

My data is confounded by driver sizes, and challenged by sample size and variety. I do wonder if smaller drivers show more changes with break-in, but since the HiVi is the only small driver I have measured it's hard to say that it represents a trend. I certainly haven't seen dramatic changes in tweeter response after break-in or use. I have some data, would be willing to post that as well, it's boring. Additional data and observations are welcome!
 
Last edited:

MaxwellsEq

Major Contributor
Joined
Aug 18, 2020
Messages
1,705
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2,548
The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:
  • I hear on various forums that you can facilitate the break-in of your speakers by placing them face to face and wiring one out of phase. Turn the volume up. Walk away. Come back later.
  • Stores sell things to facilitate break-in. I suggest bank accounts are the only thing that's suffering break-in.;)
  • I've been flamed on the usual forums for suggesting that a person should enjoy their new speakers and ignore any audible effects of break-in. I think most of the changes in the first few hours or days of getting new gear is the listener, not the gear. Despite that some people won't listen to their new HiFi until it has been subjected to various break-in procedures, seemingly out of some compulsion.
  • And of course major manufacturers from time to time make a big deal about break-in. According to some, you should expect pretty large differences after break-in. And break-in will take some time. And things will always sound better.
To be clear, I think speaker break-in (aka run-in) is measurable but typically tiny and should typically be ignored. Wear-out is real too, and some of the above practices at high SPL are aging to wear-out, which is different than break-in. The videos of people advocating this are available on YouTube. The culture exists. Kef even mentions this culture:

I belong firmly to a school that isn't quite listed in Kef's marketing statement. I know that drivers do change under break-in; I have measured it. The measurements I have taken and seen tell me break-in is tiny, and smaller than a change in room temperature or voice-coil temperature that a speaker will see under normal operation. I have shown this with a few drivers, I did some fairly careful measurements with a Seas W18 metal cone woofer and a JBL 2216Nd paper 15" cone woofer. Both of those drivers showed very small changes with break-in, even after 6 months of use on the JBL. The JBL in particular changed so little, hard to imagine hearing or even being able to measure with a microphone a significant change in system output in a carefully controlled aging experiment. Certainly way below environmental effects like what the thermostat is set at or how hard have the drivers been playing over the past few minutes or hours.

Since the subject came up again, I thought it a good time to revisit this topic with some unused drivers I have lying around.
I have two Peerless 831724 10" woofers and two Audax HP210GO 8" woofers, with synthetic cones. I also have four HiVi B3N metal cone micro-woofers.
View attachment 336056

I am presenting the measurements of these drivers before and after break-in. Each set of drivers was broken-in at ambient room conditions for 6 hours, with a signal I thought was sufficient. I don't quantify 'sufficient', except to say I drove them moderately hard with bass for 3 hours, and 3 more hours with pink noise. I specifically kept them well within their power limits, my goal was not to wear them out. I also explore the impact of moderate temperature changes both due to the break-in stress and due to external heating and cooling.

The heating and cooling is primitive. 10 mins in the refrigerator for cooling. I used a space-heater to elevate the temperatures, measurements were made with the heater off since the airflow has significant impact on the results.

View attachment 336097

Figure 1 shows the results of a break-in and temperature experiment on an Audax woofer. The raw driver was first measured (runs 1 and 2), then put in a refrigerator for 10 mins, then measured again (Runs 3 and 4). The speaker was then broken-in for 6 hours as described above, and measured immediately after while still hot from stress (Run 5). Then I allowed the driver to cool off to get the post-break-in measurements (Runs 6 and 7). The driver was then subjected to heat from a small space-heater (Runs 8-14). The space heater was moved to attempt to increase the heat, which most notably impacted measurement 14. Finally, after cooling off, the driver was remeasured (Run 15).

View attachment 336062

To better summarize the data, the changes in f(s) are normalized to the average of the measurements made right out of the box, which is 44.0 Hz.
View attachment 336085

Break-in changed f(s) changed by 1.8%, this is small. Not much bigger compared to putting the driver in the refrigerator for 10 mins (1.2%). Not much bigger than the heat from the application of stress (1.5%). And smaller than the impact of the space heater. Perhaps I could have measured the speaker in the refrigerator while cooling it to get better temperature granularity. And longer cool-down to explore larger fluctuations. And applied more heat, perhaps heat to the motor with a hot plate. And correlated it to actual temperatures of the driver components. But despite this rough approach, I think this is a good approximation of some of the changes that will occur in a home.

In summary, this Audax woofer break-in data shows modest changes in f(s) and other parameters. These changes are smaller than environmental effects. It's hard to imagine the measured break-in changes are audible even under ideal conditions.

Figure 3 shows a simple break-in experiment on a pair of Peerless 10" drivers.
View attachment 336098

The Peerless drivers show large mismatch in parameters between the two. They show individually 2.6% and 3.2% change in f(s) post break-in. Run 3 suggests that the impact of the heat due to the break-in stress is larger than the changes due to break-in. And the trends from Run 3 to Run 8 suggest that it took hours for the driver to dissipate the heat from the stress and come back to equilibrium with the room.

The Peerless 10" woofers are more sensitive to the temperature effects of break-in than the actual physical changes due to break-in, the evidence is the f(s) trend from run 3 to run 8 as the driver cools back down to room T. Speaker to speaker matching is also larger than break-in effect. Unclear if the mismatch is due to defect or normal run to run variation. It's difficult to believe these small differences are audible.

Figure 4 shows the results of break-in on four HiVi B3N micro-speakers:
View attachment 336122

These drivers' f(s) changes 10% from new. This is quite large compared to all previous drivers I have measured.
I don't know how long it took for the drivers to change. I did confirm that further stress causes no additional change.

This small HiVi speaker does change appreciably with stress. All four units behave the same with stress, despite the fact one driver has outlier L(e). This is the lone observation of a significant break-in effect. Perhaps the size of the driver can allow large changes to occur compared to a larger driver. Perhaps these HiVi drivers are an outlier for break-in.

This is the first time I have seen dramatic changes with stress like this. That being said, I have only made ad-hoc observations and half-dozen concerted measurement attempts to see how big the break-in effect is. But this is the only driver I have ever found to have significant change. Do metal cone drivers break in more? The JBL 15" paper cone woofer I refenced above changed from new only 1-2% over 6 months of heavy use.

My data is confounded by driver sizes, and challenged by sample size and variety. I do wonder if smaller drivers show more changes with break-in, but since the HiVi is the only small driver I have measured it's hard to say that it represents a trend. I certainly haven't seen dramatic changes in tweeter response after break-in or use. I have some data, would be willing to post that as well, it's boring. Additional data and observations are welcome!
This is an excellent piece of labwork! Thanks for taking the time to come up with the experiment and then running it across multiple drivers.

What this seems to consistently show is that, even when you have had your speakers for some years, they will probably measure differently on a hot day than a cold day and will measure differently at the end of a long loud session than they do at the start of it (common knowledge amongst PA engineers). Whether these variations are audible, is not clear. But these variations are bigger than the differences between a brand new speaker and one that's been burned in for hours.

If you have the patience, I'd like to read your tweeter research as well.
 

HarmonicTHD

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The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:
  • I hear on various forums that you can facilitate the break-in of your speakers by placing them face to face and wiring one out of phase. Turn the volume up. Walk away. Come back later.
  • Stores sell things to facilitate break-in. I suggest bank accounts are the only thing that's suffering break-in.;)
  • I've been flamed on the usual forums for suggesting that a person should enjoy their new speakers and ignore any audible effects of break-in. I think most of the changes in the first few hours or days of getting new gear is the listener, not the gear. Despite that some people won't listen to their new HiFi until it has been subjected to various break-in procedures, seemingly out of some compulsion.
  • And of course major manufacturers from time to time make a big deal about break-in. According to some, you should expect pretty large differences after break-in. And break-in will take some time. And things will always sound better.
To be clear, I think speaker break-in (aka run-in) is measurable but typically tiny and should typically be ignored. Wear-out is real too, and some of the above practices at high SPL are aging to wear-out, which is different than break-in. The videos of people advocating this are available on YouTube. The culture exists. Kef even mentions this culture:

I belong firmly to a school that isn't quite listed in Kef's marketing statement. I know that drivers do change under break-in; I have measured it. The measurements I have taken and seen tell me break-in is tiny, and smaller than a change in room temperature or voice-coil temperature that a speaker will see under normal operation. I have shown this with a few drivers, I did some fairly careful measurements with a Seas W18 metal cone woofer and a JBL 2216Nd paper 15" cone woofer. Both of those drivers showed very small changes with break-in, even after 6 months of use on the JBL. The JBL in particular changed so little, hard to imagine hearing or even being able to measure with a microphone a significant change in system output in a carefully controlled aging experiment. Certainly way below environmental effects like what the thermostat is set at or how hard have the drivers been playing over the past few minutes or hours.

Since the subject came up again, I thought it a good time to revisit this topic with some unused drivers I have lying around.
I have two Peerless 831724 10" woofers and two Audax HP210GO 8" woofers, with synthetic cones. I also have four HiVi B3N metal cone micro-woofers.
View attachment 336056

I am presenting the measurements of these drivers before and after break-in. Each set of drivers was broken-in at ambient room conditions for 6 hours, with a signal I thought was sufficient. I don't quantify 'sufficient', except to say I drove them moderately hard with bass for 3 hours, and 3 more hours with pink noise. I specifically kept them well within their power limits, my goal was not to wear them out. I also explore the impact of moderate temperature changes both due to the break-in stress and due to external heating and cooling.

The heating and cooling is primitive. 10 mins in the refrigerator for cooling. I used a space-heater to elevate the temperatures, measurements were made with the heater off since the airflow has significant impact on the results.

View attachment 336097

Figure 1 shows the results of a break-in and temperature experiment on an Audax woofer. The raw driver was first measured (runs 1 and 2), then put in a refrigerator for 10 mins, then measured again (Runs 3 and 4). The speaker was then broken-in for 6 hours as described above, and measured immediately after while still hot from stress (Run 5). Then I allowed the driver to cool off to get the post-break-in measurements (Runs 6 and 7). The driver was then subjected to heat from a small space-heater (Runs 8-14). The space heater was moved to attempt to increase the heat, which most notably impacted measurement 14. Finally, after cooling off, the driver was remeasured (Run 15).

View attachment 336062

To better summarize the data, the changes in f(s) are normalized to the average of the measurements made right out of the box, which is 44.0 Hz.
View attachment 336085

Break-in changed f(s) changed by 1.8%, this is small. Not much bigger compared to putting the driver in the refrigerator for 10 mins (1.2%). Not much bigger than the heat from the application of stress (1.5%). And smaller than the impact of the space heater. Perhaps I could have measured the speaker in the refrigerator while cooling it to get better temperature granularity. And longer cool-down to explore larger fluctuations. And applied more heat, perhaps heat to the motor with a hot plate. And correlated it to actual temperatures of the driver components. But despite this rough approach, I think this is a good approximation of some of the changes that will occur in a home.

In summary, this Audax woofer break-in data shows modest changes in f(s) and other parameters. These changes are smaller than environmental effects. It's hard to imagine the measured break-in changes are audible even under ideal conditions.

Figure 3 shows a simple break-in experiment on a pair of Peerless 10" drivers.
View attachment 336098

The Peerless drivers show large mismatch in parameters between the two. They show individually 2.6% and 3.2% change in f(s) post break-in. Run 3 suggests that the impact of the heat due to the break-in stress is larger than the changes due to break-in. And the trends from Run 3 to Run 8 suggest that it took hours for the driver to dissipate the heat from the stress and come back to equilibrium with the room.

The Peerless 10" woofers are more sensitive to the temperature effects of break-in than the actual physical changes due to break-in, the evidence is the f(s) trend from run 3 to run 8 as the driver cools back down to room T. Speaker to speaker matching is also larger than break-in effect. Unclear if the mismatch is due to defect or normal run to run variation. It's difficult to believe these small differences are audible.

Figure 4 shows the results of break-in on four HiVi B3N micro-speakers:
View attachment 336122

These drivers' f(s) changes 10% from new. This is quite large compared to all previous drivers I have measured.
I don't know how long it took for the drivers to change. I did confirm that further stress causes no additional change.

This small HiVi speaker does change appreciably with stress. All four units behave the same with stress, despite the fact one driver has outlier L(e). This is the lone observation of a significant break-in effect. Perhaps the size of the driver can allow large changes to occur compared to a larger driver. Perhaps these HiVi drivers are an outlier for break-in.

This is the first time I have seen dramatic changes with stress like this. That being said, I have only made ad-hoc observations and half-dozen concerted measurement attempts to see how big the break-in effect is. But this is the only driver I have ever found to have significant change. Do metal cone drivers break in more? The JBL 15" paper cone woofer I refenced above changed from new only 1-2% over 6 months of heavy use.

My data is confounded by driver sizes, and challenged by sample size and variety. I do wonder if smaller drivers show more changes with break-in, but since the HiVi is the only small driver I have measured it's hard to say that it represents a trend. I certainly haven't seen dramatic changes in tweeter response after break-in or use. I have some data, would be willing to post that as well, it's boring. Additional data and observations are welcome!
Very nice. This is what I would have expected from KEF and not such a handwaving marketing article, which probably was intended for the snake oil crowd.

The „facts“ @jackocleebrown recently posted did not convince with regard to audibility and had quite a few assumptions in them, which have not been tested. But please correct me if I am wrong.
 

OldHvyMec

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Everything changes it's just a fact. The question with break-in is if it makes a difference in performance and is there an audible change.

Yes to the first and yes/no to the second. As a sub or bass driver breaks-in the suspension on the spider (depending on design) becomes more
relaxed in both directions while still returning to center. In other words it takes less horsepower to push the cone against the spring to a given XMax.

Second; if it takes less power to achieve the same Xmax on the cone, the amount of air being pushed is greater for the same amount of power being
used. In other words as they break-in it cost less to hear the same SPL from the same driver.

How much is that over the life of a driver vs the break-in time? I don't know, my concern is to alway get past the first 1-300 hours of set up, tweakin',
obsessing, fiddling and just getting used to the new drivers. I'm not a big fan of scrutinizing my own speakers. BUT if someone is going to do it, LOL.

I used a lot of isolation product to decouple. I know this, when I lift anything off a carpet or vinyl the cabinet/shelf leaves an impression in both. The
time it takes to leave a mark on either, (that won't recover) is the time it takes to break-in the drivers that set and vibrated their way down like a
jackhammer on a carpet or vinyl.

Everything changes, and settles down. Cabinets to floors, ears to sound, number of glasses of wine.

The biggest thing is to MOVE ON and realized if it's about the music, then it's about the music, not everything but the music including the type of wine.

OK this is a Science Review Forum, I'll give you that!! Interesting..

Regards
 

jackocleebrown

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The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:
  • I hear on various forums that you can facilitate the break-in of your speakers by placing them face to face and wiring one out of phase. Turn the volume up. Walk away. Come back later.
  • Stores sell things to facilitate break-in. I suggest bank accounts are the only thing that's suffering break-in.;)
  • I've been flamed on the usual forums for suggesting that a person should enjoy their new speakers and ignore any audible effects of break-in. I think most of the changes in the first few hours or days of getting new gear is the listener, not the gear. Despite that some people won't listen to their new HiFi until it has been subjected to various break-in procedures, seemingly out of some compulsion.
  • And of course major manufacturers from time to time make a big deal about break-in. According to some, you should expect pretty large differences after break-in. And break-in will take some time. And things will always sound better.
To be clear, I think speaker break-in (aka run-in) is measurable but typically tiny and should typically be ignored. Wear-out is real too, and some of the above practices at high SPL are aging to wear-out, which is different than break-in. The videos of people advocating this are available on YouTube. The culture exists. Kef even mentions this culture:

I belong firmly to a school that isn't quite listed in Kef's marketing statement. I know that drivers do change under break-in; I have measured it. The measurements I have taken and seen tell me break-in is tiny, and smaller than a change in room temperature or voice-coil temperature that a speaker will see under normal operation. I have shown this with a few drivers, I did some fairly careful measurements with a Seas W18 metal cone woofer and a JBL 2216Nd paper 15" cone woofer. Both of those drivers showed very small changes with break-in, even after 6 months of use on the JBL. The JBL in particular changed so little, hard to imagine hearing or even being able to measure with a microphone a significant change in system output in a carefully controlled aging experiment. Certainly way below environmental effects like what the thermostat is set at or how hard have the drivers been playing over the past few minutes or hours.

Since the subject came up again, I thought it a good time to revisit this topic with some unused drivers I have lying around.
I have two Peerless 831724 10" woofers and two Audax HP210GO 8" woofers, with synthetic cones. I also have four HiVi B3N metal cone micro-woofers.
View attachment 336056

I am presenting the measurements of these drivers before and after break-in. Each set of drivers was broken-in at ambient room conditions for 6 hours, with a signal I thought was sufficient. I don't quantify 'sufficient', except to say I drove them moderately hard with bass for 3 hours, and 3 more hours with pink noise. I specifically kept them well within their power limits, my goal was not to wear them out. I also explore the impact of moderate temperature changes both due to the break-in stress and due to external heating and cooling.

The heating and cooling is primitive. 10 mins in the refrigerator for cooling. I used a space-heater to elevate the temperatures, measurements were made with the heater off since the airflow has significant impact on the results.

View attachment 336097

Figure 1 shows the results of a break-in and temperature experiment on an Audax woofer. The raw driver was first measured (runs 1 and 2), then put in a refrigerator for 10 mins, then measured again (Runs 3 and 4). The speaker was then broken-in for 6 hours as described above, and measured immediately after while still hot from stress (Run 5). Then I allowed the driver to cool off to get the post-break-in measurements (Runs 6 and 7). The driver was then subjected to heat from a small space-heater (Runs 8-14). The space heater was moved to attempt to increase the heat, which most notably impacted measurement 14. Finally, after cooling off, the driver was remeasured (Run 15).

View attachment 336062

To better summarize the data, the changes in f(s) are normalized to the average of the measurements made right out of the box, which is 44.0 Hz.
View attachment 336085

Break-in changed f(s) changed by 1.8%, this is small. Not much bigger compared to putting the driver in the refrigerator for 10 mins (1.2%). Not much bigger than the heat from the application of stress (1.5%). And smaller than the impact of the space heater. Perhaps I could have measured the speaker in the refrigerator while cooling it to get better temperature granularity. And longer cool-down to explore larger fluctuations. And applied more heat, perhaps heat to the motor with a hot plate. And correlated it to actual temperatures of the driver components. But despite this rough approach, I think this is a good approximation of some of the changes that will occur in a home.

In summary, this Audax woofer break-in data shows modest changes in f(s) and other parameters. These changes are smaller than environmental effects. It's hard to imagine the measured break-in changes are audible even under ideal conditions.

Figure 3 shows a simple break-in experiment on a pair of Peerless 10" drivers.
View attachment 336098

The Peerless drivers show large mismatch in parameters between the two. They show individually 2.6% and 3.2% change in f(s) post break-in. Run 3 suggests that the impact of the heat due to the break-in stress is larger than the changes due to break-in. And the trends from Run 3 to Run 8 suggest that it took hours for the driver to dissipate the heat from the stress and come back to equilibrium with the room.

The Peerless 10" woofers are more sensitive to the temperature effects of break-in than the actual physical changes due to break-in, the evidence is the f(s) trend from run 3 to run 8 as the driver cools back down to room T. Speaker to speaker matching is also larger than break-in effect. Unclear if the mismatch is due to defect or normal run to run variation. It's difficult to believe these small differences are audible.

Figure 4 shows the results of break-in on four HiVi B3N micro-speakers:
View attachment 336122

These drivers' f(s) changes 10% from new. This is quite large compared to all previous drivers I have measured.
I don't know how long it took for the drivers to change. I did confirm that further stress causes no additional change.

This small HiVi speaker does change appreciably with stress. All four units behave the same with stress, despite the fact one driver has outlier L(e). This is the lone observation of a significant break-in effect. Perhaps the size of the driver can allow large changes to occur compared to a larger driver. Perhaps these HiVi drivers are an outlier for break-in.

This is the first time I have seen dramatic changes with stress like this. That being said, I have only made ad-hoc observations and half-dozen concerted measurement attempts to see how big the break-in effect is. But this is the only driver I have ever found to have significant change. Do metal cone drivers break in more? The JBL 15" paper cone woofer I refenced above changed from new only 1-2% over 6 months of heavy use.

My data is confounded by driver sizes, and challenged by sample size and variety. I do wonder if smaller drivers show more changes with break-in, but since the HiVi is the only small driver I have measured it's hard to say that it represents a trend. I certainly haven't seen dramatic changes in tweeter response after break-in or use. I have some data, would be willing to post that as well, it's boring. Additional data and observations are welcome!

Hi @MAB, I really admire the thoroughness of your study. My experience is a bit different. Only today we have a driver in development where we are discussing Fs shift after production. Using this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at 18 Vrms for around 10mins (to check robustness of the assembly) the Fs dropped to 49Hz.

Although this is just one example, and I haven't got a thorough database of measurements to share, it's totally typical of what we see in practice. I can't help but wonder if the drivers you have on hand have been already swept in free-air at some point. Sweeping in free-air tends to run in drivers much faster than once they're in the system because the excursion is higher. I don't know standard production process at other manufacturers but it may be possible that some are sweeping at high voltage at the end of production to get over the break-in phase?

I'll do my best to collect some routine data on Fs drop so that next time I can share more concrete results with everybody. I know my reply on the R3 thread was some-what anecdotal, but is is 100% based on real world experience rather than theoretical musings.

Best wishes,
Jack.
 

ctrl

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Hi @MAB, I really admire the thoroughness of your study. My experience is a bit different. Only today we have a driver in development where we are discussing Fs shift after production. Using this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at 18 Vrms for around 10mins (to check robustness of the assembly) the Fs dropped to 49Hz.
I don't see any contradiction between your data and the results of @MAB.

The fact that a consumer receives a loudspeaker that comes directly from the production line with no QA testing should only be the case with very cheap loudspeakers.

With "good" speakers, the QA of the driver manufacturer and later the QA of the speaker manufacturer will have moved the cones of the drivers.
So virtually every driver has already undergone at least one or two short initial "break-in" before the end customer receives the product - QA example here. And after this "initial break-in" a good driver should only show minor TSP changes.

With 18 Vrms for around 10mins and I assume with frequencies below Fs, the driver was probably operated at Xmax. Your 15% Fs shift, measured directly after the test, should not be permanent with good driver quality. Leave the driver on the shelf for a week and then measure Fs again. The driver will then most likely no longer have 15% Fs shift - but I suspect you already know that ;)

Before mounting, I usually test drivers for less than a minute with a sine wave below Fs to be able to hear possible manufacturing defects (e.g. rubbing noises). After that the drivers nearly don't change even after years:
1703245292497.png 1703245309844.png
 

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Hi @MAB, I really admire the thoroughness of your study. My experience is a bit different. Only today we have a driver in development where we are discussing Fs shift after production. Using this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at 18 Vrms for around 10mins (to check robustness of the assembly) the Fs dropped to 49Hz.

Although this is just one example, and I haven't got a thorough database of measurements to share, it's totally typical of what we see in practice. I can't help but wonder if the drivers you have on hand have been already swept in free-air at some point. Sweeping in free-air tends to run in drivers much faster than once they're in the system because the excursion is higher. I don't know standard production process at other manufacturers but it may be possible that some are sweeping at high voltage at the end of production to get over the break-in phase?

I'll do my best to collect some routine data on Fs drop so that next time I can share more concrete results with everybody. I know my reply on the R3 thread was some-what anecdotal, but is is 100% based on real world experience rather than theoretical musings.

Best wishes,
Jack.
Thank you. Appreciate it.
 
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ryanosaur

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Marketing bs.
Use your speakers until your ears adjust to the way they sound. If you still don’t like what you hear, you didn’t do it long enough. :p

But… if I run them in another hundred hours, I’ll miss the return window!

#It gets better!

:rolleyes:
 

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The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:
  • I hear on various forums that you can facilitate the break-in of your speakers by placing them face to face and wiring one out of phase. Turn the volume up. Walk away. Come back later.
  • Stores sell things to facilitate break-in. I suggest bank accounts are the only thing that's suffering break-in.;)
  • I've been flamed on the usual forums for suggesting that a person should enjoy their new speakers and ignore any audible effects of break-in. I think most of the changes in the first few hours or days of getting new gear is the listener, not the gear. Despite that some people won't listen to their new HiFi until it has been subjected to various break-in procedures, seemingly out of some compulsion.
  • And of course major manufacturers from time to time make a big deal about break-in. According to some, you should expect pretty large differences after break-in. And break-in will take some time. And things will always sound better.
To be clear, I think speaker break-in (aka run-in) is measurable but typically tiny and should typically be ignored. Wear-out is real too, and some of the above practices at high SPL are aging to wear-out, which is different than break-in. The videos of people advocating this are available on YouTube. The culture exists. Kef even mentions this culture:

I belong firmly to a school that isn't quite listed in Kef's marketing statement. I know that drivers do change under break-in; I have measured it. The measurements I have taken and seen tell me break-in is tiny, and smaller than a change in room temperature or voice-coil temperature that a speaker will see under normal operation. I have shown this with a few drivers, I did some fairly careful measurements with a Seas W18 metal cone woofer and a JBL 2216Nd paper 15" cone woofer. Both of those drivers showed very small changes with break-in, even after 6 months of use on the JBL. The JBL in particular changed so little, hard to imagine hearing or even being able to measure with a microphone a significant change in system output in a carefully controlled aging experiment. Certainly way below environmental effects like what the thermostat is set at or how hard have the drivers been playing over the past few minutes or hours.

Since the subject came up again, I thought it a good time to revisit this topic with some unused drivers I have lying around.
I have two Peerless 831724 10" woofers and two Audax HP210GO 8" woofers, with synthetic cones. I also have four HiVi B3N metal cone micro-woofers.
View attachment 336056

I am presenting the measurements of these drivers before and after break-in. Each set of drivers was broken-in at ambient room conditions for 6 hours, with a signal I thought was sufficient. I don't quantify 'sufficient', except to say I drove them moderately hard with bass for 3 hours, and 3 more hours with pink noise. I specifically kept them well within their power limits, my goal was not to wear them out. I also explore the impact of moderate temperature changes both due to the break-in stress and due to external heating and cooling.

The heating and cooling is primitive. 10 mins in the refrigerator for cooling. I used a space-heater to elevate the temperatures, measurements were made with the heater off since the airflow has significant impact on the results.

View attachment 336097

Figure 1 shows the results of a break-in and temperature experiment on an Audax woofer. The raw driver was first measured (runs 1 and 2), then put in a refrigerator for 10 mins, then measured again (Runs 3 and 4). The speaker was then broken-in for 6 hours as described above, and measured immediately after while still hot from stress (Run 5). Then I allowed the driver to cool off to get the post-break-in measurements (Runs 6 and 7). The driver was then subjected to heat from a small space-heater (Runs 8-14). The space heater was moved to attempt to increase the heat, which most notably impacted measurement 14. Finally, after cooling off, the driver was remeasured (Run 15).

View attachment 336062

To better summarize the data, the changes in f(s) are normalized to the average of the measurements made right out of the box, which is 44.0 Hz.
View attachment 336085

Break-in changed f(s) changed by 1.8%, this is small. Not much bigger compared to putting the driver in the refrigerator for 10 mins (1.2%). Not much bigger than the heat from the application of stress (1.5%). And smaller than the impact of the space heater. Perhaps I could have measured the speaker in the refrigerator while cooling it to get better temperature granularity. And longer cool-down to explore larger fluctuations. And applied more heat, perhaps heat to the motor with a hot plate. And correlated it to actual temperatures of the driver components. But despite this rough approach, I think this is a good approximation of some of the changes that will occur in a home.

In summary, this Audax woofer break-in data shows modest changes in f(s) and other parameters. These changes are smaller than environmental effects. It's hard to imagine the measured break-in changes are audible even under ideal conditions.

Figure 3 shows a simple break-in experiment on a pair of Peerless 10" drivers.
View attachment 336098

The Peerless drivers show large mismatch in parameters between the two. They show individually 2.6% and 3.2% change in f(s) post break-in. Run 3 suggests that the impact of the heat due to the break-in stress is larger than the changes due to break-in. And the trends from Run 3 to Run 8 suggest that it took hours for the driver to dissipate the heat from the stress and come back to equilibrium with the room.

The Peerless 10" woofers are more sensitive to the temperature effects of break-in than the actual physical changes due to break-in, the evidence is the f(s) trend from run 3 to run 8 as the driver cools back down to room T. Speaker to speaker matching is also larger than break-in effect. Unclear if the mismatch is due to defect or normal run to run variation. It's difficult to believe these small differences are audible.

Figure 4 shows the results of break-in on four HiVi B3N micro-speakers:
View attachment 336122

These drivers' f(s) changes 10% from new. This is quite large compared to all previous drivers I have measured.
I don't know how long it took for the drivers to change. I did confirm that further stress causes no additional change.

This small HiVi speaker does change appreciably with stress. All four units behave the same with stress, despite the fact one driver has outlier L(e). This is the lone observation of a significant break-in effect. Perhaps the size of the driver can allow large changes to occur compared to a larger driver. Perhaps these HiVi drivers are an outlier for break-in.

This is the first time I have seen dramatic changes with stress like this. That being said, I have only made ad-hoc observations and half-dozen concerted measurement attempts to see how big the break-in effect is. But this is the only driver I have ever found to have significant change. Do metal cone drivers break in more? The JBL 15" paper cone woofer I refenced above changed from new only 1-2% over 6 months of heavy use.

My data is confounded by driver sizes, and challenged by sample size and variety. I do wonder if smaller drivers show more changes with break-in, but since the HiVi is the only small driver I have measured it's hard to say that it represents a trend. I certainly haven't seen dramatic changes in tweeter response after break-in or use. I have some data, would be willing to post that as well, it's boring. Additional data and observations are welcome!
Okay, knee jerk quip aside, cool. :)

I’ve always found it funny that smaller independent designers say run in is a myth whereas larger companies swear by it. The simple fact that any changes to the driver will happen relatively quickly and are also relatively minor.
Running in Drivers does change the suspension, but I’ve not seen enough change to warrant a redesign between new in-box or run-in driver. Likewise, measuring hot or cold… a run-in Driver rebounds closer to original condition after it cools down.
But it’s still not enough to change how a Speaker should be designed. …and the designers I’ve spoken with have never said they have a winter and summer model of their designs, or tropical/arctic models. ;)

*shrugs

And the sun will still rise in the morning. :D
 

jhaider

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Hi @MABUsing this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at 18 Vrms for around 10mins (to check robustness of the assembly) the Fs dropped to 49Hz.

Similar to @ctrl, I wonder if the emphasized-by-me above text is the key here. In addition to those points re QA and settling time, I wonder if just the act of handling the drivers by transporting them to the cabinet factory, screwing them into the cabinets, and shipping them to end users provides a similar effect just by bumping them around a bit.

Put another way, if you track a driver from production to a finished speaker that’s been packed, shipped, open, and set up for use - do similar changes occur?
 

ryanosaur

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Similar to @ctrl, I wonder if the emphasized-by-me above text is the key here. In addition to those points re QA and settling time, I wonder if just the act of handling the drivers by transporting them to the cabinet factory, screwing them into the cabinets, and shipping them to end users provides a similar effect just by bumping them around a bit.

Put another way, if you track a driver from production to a finished speaker that’s been packed, shipped, open, and set up for use - do similar changes occur?
The Spider needs to be exercised, not just jostled. ;)
I had been instructed once to run a test tone near Fs through a driver, pulsing it for about 10 second intervals for a minute or two. According to the Driver designer, that is enough to loosen up the suspension and achieve a more realistic day to day performance metric to design the cabinet around.
 
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MAB

MAB

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Hi @MAB, I really admire the thoroughness of your study. My experience is a bit different. Only today we have a driver in development where we are discussing Fs shift after production. Using this prototype as an example, the Fs directly after assembly was 57Hz and after sweeping in free air at 18 Vrms for around 10mins (to check robustness of the assembly) the Fs dropped to 49Hz.

Although this is just one example, and I haven't got a thorough database of measurements to share, it's totally typical of what we see in practice. I can't help but wonder if the drivers you have on hand have been already swept in free-air at some point. Sweeping in free-air tends to run in drivers much faster than once they're in the system because the excursion is higher. I don't know standard production process at other manufacturers but it may be possible that some are sweeping at high voltage at the end of production to get over the break-in phase?

I'll do my best to collect some routine data on Fs drop so that next time I can share more concrete results with everybody. I know my reply on the R3 thread was some-what anecdotal, but is is 100% based on real world experience rather than theoretical musings.

Best wishes,
Jack.
I would like to see those measurements.
Your experience is different than mine, I have only measured hundreds (maybe thousands) of drivers from a variety of manufacturers.:cool: Most of my measurements were focused on making sure the product from the manufacturer isn't defective prior to installation or removal (voice-coil rub, etc.). Along the way I got to see actual field data on break-in, and my experience is it is 1-2% for a raw driver, with changes in system response being negligible. For instance here is the actual response of a pre- and post-break-in Wavecore woofer (based on their published data):
index.php


I hope we agree this is inaudible.


Even the HiVi B3N micro-woofer which changes about 10% after break-in is only 2dB different response in a 2 liter cabinet after break-in. Part of that is huge difference between published spec and actual measurement. Perhaps if HiVi published accurate data, it would suggest a different box size with less of a peak and have less sensitivity to the actual break-in change.:facepalm:
1703362159805.png


It is a tiny speaker. And @ctrl has provided the clue as to why it sees such a large change in f(s) with break-in.
The TS parameter most likely to change during "burn-in" is the compliance Cms. This means that fs of the driver also changes, as the following applies:
fs =1 / (2*pi*(Cms*Mms)^0.5)
Is it the small speaker, low mass, high sensitivity to C(ms)?

Can you tell me more about the driver you saw such large f(s) changes in? I do believe your development case is not typical of what is sold to end user.
 
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thank you for sharing!

Even if for sure not as relevant as temperature, i would suggest to try to have some way to look at the potential influence of moisture in your results. It might be more or less relevant depending on the material, but when you are cooling and letting return to ambient temperature in uncontrolled conditions there is on the one hand the absorption of water and even condensation! depending on where you live. It might not have a measurable effect, but it might also be that it is influencing somehow your low temp measurements.
One other thing i wonder about is the different coefficient of expansion of the different parts of the driver, again referred to the cool/warm experiments, in the sense of parts of the driver changing temperature (and expanding) faster than others. Could this have an influence on the results vs taking the measurements in a situation where the temperature is cold or warm but not changing?
Lastly, for the big driver you show in the picture, only 10 minutes in the refrigerator might not be enough. I would suggest to leave them for a longer period specially if you are running and want to compare the effects on smaller and bigger drivers.

regarding the general subject of break in: i know that everyone agrees on this: it would be foolish to think that at least the parts made of organic/polymeric material don't change over time and applied strain, and most specially right after production. There are resins that need to fully cure, to adapt to new ambient conditions, etc. etc. (If all this has a relevant effect on the sound, that i don't know)
 
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MAB

MAB

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thank you for sharing!

Even if for sure not as relevant as temperature, i would suggest to try to have some way to look at the potential influence of moisture in your results. It might be more or less relevant depending on the material, but when you are cooling and letting return to ambient temperature in uncontrolled conditions there is on the one hand the absorption of water and even condensation! depending on where you live. It might not have a measurable effect, but it might also be that it is influencing somehow your low temp measurements.
One other thing i wonder about is the different coefficient of expansion of the different parts of the driver, again referred to the cool/warm experiments, in the sense of parts of the driver changing temperature (and expanding) faster than others. Could this have an influence on the results vs taking the measurements in a situation where the temperature is cold or warm but not changing?
Lastly, for the big driver you show in the picture, only 10 minutes in the refrigerator might not be enough. I would suggest to leave them for a longer period specially if you are running and want to compare the effects on smaller and bigger drivers.
I put it the fridge only to show that 10 mins in a cold environment has a much larger effect than 6 months of use. My intent is to show a brief stint in cold or moderate heat will produce changes similar or even larger than the measured break-in. Yes, a longer stint in the fridge, or a larger and more realistic heat load simulating hot motor would also make much larger changes. But, the point here is break-in is small compared to mild temperature swings.
 

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I put it the fridge only to show that 10 mins in a cold environment has a much larger effect than 6 months of use. My intent is to show a brief stint in cold or moderate heat will produce changes similar or even larger than the measured break-in. Yes, a longer stint in the fridge, or a larger and more realistic heat load simulating hot motor would also make much larger changes. But, the point here is break-in is small compared to mild temperature swings.
What I was trying to say is that if you leave the driver only 10 minutes in the fridge, the temperature it actually reaches will be very much dependent of its mass, making a comparison with a driver with a different mass more difficult and the interpretation of the absolute result more difficult as well. At what temperature was the driver when you measured it? Nobody knows. But if you leave it a long enough time inside, the temperature of the driver will become closer to the temperature i side the fridge and you will be able to compare the effect between different drivers and have a good guess of the actual temperature the driver is at when you measure it. Your conclusions would be probably the same, but it is a matter of quality of data and controlled conditions, a must when running any experiment, nothing else.
 
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What I was trying to say is that if you leave the driver only 10 minutes in the fridge, the temperature it actually reaches will be very much dependent of its mass, making a comparison with a driver with a different mass more difficult and the interpretation of the absolute result more difficult as well. At what temperature was the driver when you measured it? Nobody knows. But if you leave it a long enough time inside, the temperature of the driver will become closer to the temperature i side the fridge and you will be able to compare the effect between different drivers and have a good guess of the actual temperature the driver is at when you measure it. Your conclusions would be probably the same, but it is a matter of quality of data and controlled conditions, a must when running any experiment, nothing else.
Yes, I totally agree. The data quality of the temperature change is low for the fridge and the heater. My thermometer broke so I wasn't even able to quantify temperatures of the cones. And for sure the cones and suspension likely cooled at a different rate than the motor, and without doubt all of these rates are going to be different on small vs. big drivers, and nothing was in equilibrium in the refrigerator. So I just tried to simulate a thermal event that is similar to what would occur in a home (a bit of heat, a bit of cold), and show that these thermal events are large impact than the break-in.

I could set the fridge for a few different temperatures, and let the drivers soak to that target T. This would allow different drivers to all equilibrate to the same T. I could use an oven to do the heating test. The only problem is the soak times, the data suggests it takes several hours to soak to equilibrium, here is the JBL woofer after 10 mins in the fridge:
1703439554199.png

It took three hours to get back into equilibrium with the room. Perhaps a smaller driver will take shorter for the bulky parts, not sure about the cone though since it is a thin membrane.
OK, the other problem is family members coming across drivers in places where food should be.:facepalm:
Also, most of the temperatures were the oven and refrigerator have adequate control are not realistic home conditions. But if I got good enough data I could make correlations of the speaker parameters vs. T.

Another thing that I fail to capture are operating conditions and the elevated temperatures that occur while playing.
This will also dramatically differ from speaker to speaker.

B&O discusses this in a nice paper with graphs of predicted VC temperatures (they also detail a temperature experiment using a sauna:
  1. Take a woofer and put it in a cabinet
  2. Connect an amplifier to it
  3. Put it in a sauna
  4. Set the room temperature to 20° C and wait until everything in the room is the same temperature
  5. Measure the woofer’s on-axis response with a microphone
  6. Look at the pretty plot of its magnitude response
  7. Turn up the thermostat to 100° C and wait until the woofer warms up
  8. Measure the response again
  9. Look at the new pretty plot of its magnitude response
  10. Scratch your head while you ask yourself why the two measurements look so different.
bl5_voice_coil_temp_vs_time-300x243.png

Yes, they are talking about VC temperatures closing in on 200 C!
And the main thrust of their article is thermal compression. Which by the Klippel and B&O references is a difficult experiment!
 

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The subject of speaker break-in comes up often. It's also called run-in. It's different than aging, or wear-out.
  • I see people posting YouTube videos of woofers being deformed into the shape of a potato-chip, while the 'tuber yells at me to make sure and break in my drivers before ever listening to them.:facepalm:

. Additional data and observations are welcome!
Nice measurements!

"shape of a potato-chip" : I guess this is most likely caused by aliasing of the image sensor with the audio frequencies :)
 
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Nice measurement!!

"shape of a potato-chip" : I guess this is most likely caused by aliasing of the image sensor with the audio frequencies :)
Yes. It occurred to me the visual in the videos is an artifact. But it doesn't change the fact that a woofer's cone and surround turns into a complex set of distorted standing waves resembling and actual potato chip at the excursions that YouTube break-in fanatics suggest.
 
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