# Do subwoofers go through a "break-in" period?



## grampi

I've recently noticed that I've had to turn down the amp gain to my subs as they are seemingly putting out more and more output. Is it possible that my subs are getting "broken-in" and their output is actually increasing, or am I just imagining things?


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## "that boy asad"

some of them do...


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## Mooble

No, that's normal, especially subs with stiff suspensions. Once they loosen up, they will play louder and sound better.


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## michaelsil1

My Sub took months to break in (12W7) I'm not sure if pushing it harder would have speeded up the process.


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## Mooble

michaelsil1 said:


> My Sub took months to break in (12W7) I'm not sure if pushing it harder would have speeded up the process.


Speeded up, yes, but I wouldn't want to push it that hard in the beginning. Let it break in slowly IMO. Then again, it shouldn't take months either.


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## Jethro

Mooble said:


> Speeded up, yes, but I wouldn't want to push it that hard in the beginning. Let it break in slowly IMO.


Why?

The only thing you are doing is stretching out the suspension... taking it easy accomplishes nothing, and actually prolongs the break-in process. If a broken-in driver sounds 'better', wouldn't you want it broken-in sooner rather than later?


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## Mooble

Jethro said:


> Why?
> 
> The only thing you are doing is stretching out the suspension... taking it easy accomplishes nothing, and actually prolongs the break-in process. If a broken-in driver sounds 'better', wouldn't you want it broken-in sooner rather than later?


That's just my opinion. I wasn't offering it as fact. I would want to take a week to let something break-in rather than playing a test tone through it for 6 hours for instance.


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## ogahyellow

I've heard there is no such thing as a break in period. In my opinion, a break-in period would be bad since it would affect the T-S parameters from what the original specifications are. 

What i've heard about the "break-in" period is that it is psycho-acoustic more than anything. Meaning you are breaking in your ears to the sound and becoming accostomed to it. I don't believe in break-in, and I doubt I've ever heard it because I don't believe in it. 

What I have found is this http://www.audioholics.com/education/loudspeaker-basics/speaker-break-in-fact-or-fiction which asks the same question scientifically. It finds that break-in takes less than a minute, so this whole break-in phenomenon is farce. Plus have you ever heard anyone say how their system sounded WORSE after their "break-in" period? Me Neither.

The T-S changes as the components of the sub warm up, but then return to their starting values as the sub returns to its initial condition. What specifically changes as a result of a break-in period? Does anyone have data to back up the break-in claim?


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## Jethro

ogahyellow said:


> I've heard there is no such thing as a break in period. In my opinion, a break-in period would be bad since it would affect the T-S parameters from what the original specifications are.
> 
> What i've heard about the "break-in" period is that it is psycho-acoustic more than anything. Meaning you are breaking in your ears to the sound and becoming accostomed to it. I don't believe in break-in, and I doubt I've ever heard it because I don't believe in it.
> 
> What I have found is this http://www.audioholics.com/education/loudspeaker-basics/speaker-break-in-fact-or-fiction which asks the same question scientifically. It finds that break-in takes less than a minute, so this whole break-in phenomenon is farce. Plus have you ever heard anyone say how their system sounded WORSE after their "break-in" period? Me Neither.
> 
> The T-S changes as the components of the sub warm up, but then return to their starting values as the sub returns to its initial condition. What specifically changes as a result of a break-in period? Does anyone have data to back up the break-in claim?


I've measured T/S parameters of many different drivers both before and after break-in (with a 20 Hz tone for at least 6 hours), and I found that it varies greatly from driver to driver on how much of a difference break-in actually made. In some cases, drivers went through a full 12 hour session without any drop in Fs.

With my Dayton 12HF however, I saw a significant drop in Fs after 12 hours of break-in. I measured 25 Hz before break-in, and 23 Hz after -- this is the largest difference I have noticed from any of the drivers I've measured.


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## Mooble

ogahyellow said:


> I've heard there is no such thing as a break in period. In my opinion, a break-in period would be bad since it would affect the T-S parameters from what the original specifications are.
> 
> What i've heard about the "break-in" period is that it is psycho-acoustic more than anything. Meaning you are breaking in your ears to the sound and becoming accostomed to it. I don't believe in break-in, and I doubt I've ever heard it because I don't believe in it.
> 
> What I have found is this http://www.audioholics.com/education/loudspeaker-basics/speaker-break-in-fact-or-fiction which asks the same question scientifically. It finds that break-in takes less than a minute, so this whole break-in phenomenon is farce. Plus have you ever heard anyone say how their system sounded WORSE after their "break-in" period? Me Neither.
> 
> The T-S changes as the components of the sub warm up, but then return to their starting values as the sub returns to its initial condition. What specifically changes as a result of a break-in period? Does anyone have data to back up the break-in claim?


The only problem with that article is that they are testing home speakers. The surround on a 4.5" mid is nothing like a 1200 watt 12" sub. Even a 10" home woofer typically has a VERY thin surround. I've seen some subs with surrounds that were almost 2mm thick.

Maybe it is mostly psychoacoustic, but sub suspensions do loosen up after several days of playing. You can actually feel less resistance.


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## tcguy85

i believe that maybe not all but some speakers do sound better or change after x amount of time.

both my RSD mids and my Dayton HO sounded A LOT better after a week or so of playing. 

with the RSD mids i noticed a nice slow increase of mid-bass punch after about a week or so. with the sub it definitely increased in output and dug lower after a couple days. but i DO NOT believe that a speaker needs to be broken in slowly or carefully. just let em wang!

both the mids and the sub also have a very different sound depending on the temperature outside. the surrounds on the mids and sub seem to stiffen quite a bit when its really cold out.


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## squeak9798

ogahyellow said:


> What specifically changes as a result of a break-in period?


Suspension compliance (Cms)



> Does anyone have data to back up the break-in claim?


Per Vance Dickason in _The Loudspeaker Design Cookbook_, the following are measured parameters for a 6.5" Peerless woofer;

*Pre-Break In* (i.e. out of the box)
Fs: 49.9hz
Qms: 2.11
Qes: 0.44
Qts: 0.37
Vas: 16.8L

*Post-Break In* (12hrs @ 25hz, unspecified power)
Fs: 44.5hz
Qms: 1.97
Qes: 0.39
Qts: 0.33
Vas: 21.6L

However, enclosure requirements/performance will be nearly identical since the Fs/Qts ratio stays virtually the same even though there's a decent % variance in some of the parameters.

Is "break in" a myth? No, not really. As indicated, you can clearly and easily show a measurable difference in parameters. Is there going to be a readily apparent audible difference? With your _typical_ driver....probably not. With some of the stiff suspension drivers that SPL'ers use, for example.....I'd be interested in seeing some additional before and after tests


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## grampi

So in my case, since I'm running Sundown SD-1's, which are not high power handling subs, I'm more than likely experiencing the psycho thing?


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## br85

CMS will almost definitely change by a measurable amount throughout break in.


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## Toxis

ogahyellow said:


> What i've heard about the "break-in" period is that it is psycho-acoustic more than anything. Meaning you are breaking in your ears to the sound and becoming accostomed to it. I don't believe in break-in, and I doubt I've ever heard it because I don't believe in it.


Than the same could be said that your mind/ears aren't trained enough to know the subtle differences in a system after break in. To say something is psycho acoustic and saying nothing changes while highly regarded professionals like Vance Dickenson have proven otherwise just shows too many people talk on the internet without actually researching or testing. Welcome to opinions on the 'net.


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## CodeMan

grampi said:


> So in my case, since I'm running Sundown SD-1's, which are not high power handling subs, I'm more than likely experiencing the psycho thing?



What you're experiencing is the opposite of what I did. Mine sounded louder at first, and over time as I become used to it I want to turn it up more. This is normal I would think.


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## Bassnub

well im no expert.. and im no scientist... but as far as i can figure from all ive read is this...

if some guys break-in their subs, and after the break-in period they sound great... and some guys do not break in their subs, and they still sound great... 

not saying there isnt a break in period because im totally convinced there is.. whether its psychological or physical.. or maybe a bit of both is beyond me.

but as far as i can tell theres no defined "break-in" period as far as there being an actual set of rules for doing this. so ill just listen to them as i always have and enjoy the bass. 

ive got two brand new Punch 2 15's on the way  its gonna be sweet!


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## 14642

Whether the sub gets louder or not depends on the enclosure. The spider is made of some kind of woven cloth and in most cases, is made stiff by the application of some resin. The stiffer the resin, the more it's affected by the back and forth movement and the more the compliant it becomes over time. That causes a drop in the resonance, which affects the Qes, Qms and therefore, the Qts. In a sealed box, the result is a simple reduction in Fc and Qtc that attends the reduction in Fs and Qts. In a vented box, that same reduction in driver Fs and Q will increase the output of the system above Fb. The box tuning remains the same, but the response of the woofer doesn't. The output of a vented box is the sum of the output of the woofer and the port and it's the area where the port and the woofer play the same frequencies that will be affected by the break-in. 

Here's the rub, though. The suspension provides restoring force primarily below resonance and the motor does most of the work above resonance. For a midrange driver in a home cabinet, especially if the driver is crossed over above resonance (as all midrange drivers should be), the spider is never exercised very hard and wouldn't get "broken in". Woofers are used above _and_ below their resonance frequency, so they do get broken in.


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## sam3535

Bassnub said:


> well im no expert.. and im no scientist... but as far as i can figure from all ive read is this...


I read the fact that you lack the ability to read the date of the last post.


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## Brian Steele

Andy Wehmeyer said:


> Whether the sub gets louder or not depends on the enclosure. The spider is made of some kind of woven cloth and in most cases, is made stiff by the application of some resin. The stiffer the resin, the more it's affected by the back and forth movement and the more the compliant it becomes over time. That causes a drop in the resonance, which affects the Qes, Qms and therefore, the Qts.


I contributed to a message thread on this identical subject over at the Trinituner site (currently inaccessible - they're doing an upgrade at the moment, and the new site should be available from Monday). I actually had t/s parameters available for a particular driver, taken when new and again after almost a year of operation, measured personally by yours truly using a WT3. No significant change noticed. And I do tend to drive the subs hard at times . The driver in question? The Infinity 122.7W .


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## 14642

Those subs were broken in before we shipped them because they were subject to significant "break-in".

BTW, T&S parameters are usually considered to be +/- about 10% due to material variations. That goes for all speakers.


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## GlassWolf

grampi said:


> I've recently noticed that I've had to turn down the amp gain to my subs as they are seemingly putting out more and more output. Is it possible that my subs are getting "broken-in" and their output is actually increasing, or am I just imagining things?


speakers do go through a break in period, yes. it's basically a period of time for new spiders to loosen up when they're brand new and haven't really been used. They will change timbre as they go through that break-in period, too.


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## Brian Steele

Andy Wehmeyer said:


> Those subs were broken in before we shipped them because they were subject to significant "break-in".


How long is this "break-in" period? Some manufacturers claim it takes a few weeks before the parameters "settle down". I can't imagine any manufacturer doing this in-house due to the additional costs involved. - maybe I'm wrong.

BTW - I've made similar measurements for other drivers I've "recently" owned - the Adire Audio Shivas and the eD 13Kv.2, and achieved similar results. Any variations noticed were minor, and could easily be due to things like temperature variation between measurements. In the case of the eD 13Kv.2, the measured params were significantly off the published ones, and remained so after several months of operation.

It someone actually has empirical measurements that demonstrate significant changes in a subwoofer's t/s parameters after a few weeks' of normal operation, I'd sure like to see them.


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