[Affordable$$Audio]

Affordable$$Audio is pleased to announce that the December issue is now available for free download at: http://www.affordableaudio.org

Special articles on the science behind speaker break-in and the A$$A list of the best reviewed components of 2006.

Thanks for reading!!

[warnerwh]

Thanks Again! It's greatly appreciated and is my favorite magazine.

[Affordable$$Audio]

Warner:
Glad you enjoy it so much.  if you ever have any review suggestions, please email them.

[Occam]

I'm not able to get to the sound-thinking.com discussion board mentioned in your e-zine. Its seems to be an e-commerce infrastructure site. Any links that work?

[fly_fish_nz]

Interesting article on speaker burn in by Danny of GR research.  Thanks.

[Kevin Haskins]

I think I'd have a few bones to pick on the break-in article.

First... nobody who designs speakers (real designers... not some guy building a couple in his garage) doubt mechanical break-in.    The argument is over the electrical break-in for which there is zero actual data to support it.    I'm not saying caps and other parts don't break-in or at least that our perception of them doesn't change.   I'm simply saying there isn't any measured data to support it yet.

Second... the parameters measured give the impression that the T/S parameters are the defining speaker break-in event.   If you measure the unbroken-in driver in the finished enclosure design before and after you will see that the way the parameters shift has little effect on the system FR.   You have to understand that those parameters are constantly shifting in a functioning loudspeaker due to the VC heat, ambient temp, barometric pressure etc...     The micro-analyzing of T/S parameters (which are all derived from the measurement system) shed little light on the subject.    Look at the math on how the parameters are calculated by your measurement program and look at actually what it is measured and you will see that the derived parameters can vary substantially due to the measurement system rather than reality.   Also... the fact that spiders are spec'd with -+20% tolerance greatly effects all the derived parameters.   The parameters are a useful tool for picking a low frequency cabinet design but I'd not give them some mystical properties they don't deserve.   

I don't dispute any of the measurements.... just their applicability to the topic and the fact that analyzing T/S parameters falsely leads people to give some undeserved credibility to electrical break-in claims.

[Charivari]

I'm not able to get to the sound-thinking.com discussion board mentioned in your e-zine. Its seems to be an e-commerce infrastructure site. Any links that work?

The link is a bit particular thanks to the number of "Sound Thinking" websites out there. It didn't help that the server was also down for a few hours yesterday. The link that works is .org: http://www.sound-thinking.org

- JP

[Danny Richie]

Kevin, I think you should call the guy up that made these measurements and bitch at him. 

I agree with you though. The article makes one point only. Speakers (or rather woofers) do break-in and require X amount of break in time to reach a settling in point.

Now the question of the electrical burn in is harder to document as you know and may have much more to do with audible changes.

The article in no way attempted to prove that there is an audible difference. However, I have found (as have many others) that the audibility (change in sound) from the burn in time goes hand and hand with the time needed for the mechanical burn in period.

[Scotty]

Of course no one has done the obvious tests and measured Harmonic distortion and Intermodulation distortion levels before during and after a predefined breakin period or check the same parameters after six months of use. It is quite possible that the change some of us hear is related to an increase or decrease
in distortion that the speaker produces over time. There may also be a decrease in transient dynamic non-linearities as the driver breaks in as well.
Scotty

[mysticaldodo]

I'm a Malaysian and I'm embarrased with all the spam at the Malaysian HIFI forum. 

[Rob Babcock]

Cool, I'll have to check out the new issue.

[Kevin Haskins]

Kevin, I think you should call the guy up that made these measurements and bitch at him. 

I agree with you though. The article makes one point only. Speakers (or rather woofers) do break-in and require X amount of break in time to reach a settling in point.

Now the question of the electrical burn in is harder to document as you know and may have much more to do with audible changes.

The article in no way attempted to prove that there is an audible difference. However, I have found (as have many others) that the audibility (change in sound) from the burn in time goes hand and hand with the time needed for the mechanical burn in period.

I should call that jerk up and give him a tongue lashing!      All kidding aside... my main beef is that you hang out that statement in the beginning that electrical break-in is the most important aspect of speaker break-in and then you don't give us any juice to support it!   

I'm not a non-believer in break-in type behavior.   Hell... I'm burning-in transformers almost 24/7 above my office and there is a set of loudspeakers running in my warehouse breaking-in as I type this message.   I just think we should be careful about what we state as fact when in reality the best answer I can give people is "I don't know" or "it is a little bit of voodoo".   

Where the rubber meets the mat we don't have one shred of measured data to support electrical break-in.   We just have a bunch of casual observations taken by the ole flawed human perception machine.

[Kevin Haskins]

Of course no one has done the obvious tests and measured Harmonic distortion and Intermodulation distortion levels before during and after a predefined breakin period or check the same parameters after six months of use. It is quite possible that the change some of us hear is related to an increase or decrease
in distortion that the speaker produces over time. There may also be a decrease in transient dynamic non-linearities as the driver breaks in as well.
Scotty

I'm sure it has been done.   Non-linear driver behavior can be summed into three or four catagories.   BL based non-linear behavior, suspension based non-linear behavior, inductance based non-linearities and cone-break-up type non-linearities.   
The suspension non-linearities may change ever so slightly with mechanical break-in.   I'm willing to bet that the percentage change in terms of measured distortion is small.   The BL won't change unless the flux changes which could happen with a magnetic material like alnico but won't to any degree with neo or ferrite.   It would be easy to measure though if it did.    The inductance won't change simply because it is determined by the fixed quantity of the VC length and configuration and the magnetic field it acts within.   The cone damping and vibrational characteristics could change for the same reasons that a suspension may change.   Micro-cracks in the glue & laminations.   Of course cones are made from all kinds of materials and if acoustic break-in as related by subjective impressions has some validity we should see a correlation with different materials having a corresponding different type of subjective "break-in".    I think what you see instead is that everyone generalizes and break-in isn't  a scientifically acceptable phenomona outside of the pyscoacoustic field. 

[Scotty]

Kevin,my money is on suspension based non-linearity's interacting with cone breakup behavior on a dynamic basis. Changes in distortion by-products from this interaction should be measurable. Perhaps as a reduction of harmonic and intermodulation distortions. Changes in the compliance of the surround material
as a result flexure have a dramatic impact on the effectiveness of the edge termination of the cone and the absorption of the transverse sound waves traveling on the surface of cone as well as the in the cone. Reflections from the boundary of the cone edge where it is attached to the surround cause standing waves to form on the surface of cone which results in higher levels of distortion
until the surround becomes more flexible and better absorbs the transverse waves.
Scotty

[Kevin Haskins]

I agree.... it should be measurable if it is occuring.    This is a good topic and I"ll do some distortion measurements on a driver just for kicks.   The experimental proceedure would be to mount a new driver and take some distortion measurements.   I'll do 2nd, 3rd and THD to start.   I'll then run a test signal through the driver for 20 hours and retake the measurements.   If necessary I'll do another 20 hours and retake measurements.    I'll set it up so I don't move the mic or any of the measurement gear during this time and I'll take the measurements at the same driver level and the same ambient temp. 

The edge termination issues are typically caused by the interface of two non-identical materials where the density and stiffness are different.   I've never seen any difference to speak of in a non broken-in driver and a new one (FR measurements where this would show) simply because the density & stiffness of the two materials don't change to any degree.   Just the overall compliance of the spider which isn't in direct contact with the cone.

[Kevin Haskins]

Oh... there is one more non-linearity that I missed.   Tempeture based non-linear behavior due to VC heating.   That is one that would change with drive level and the nature of the signal (duty cycle).    It once again is easy to measure and I dont see a mechanism by which break-in would effect it.

[Rob Babcock]

Another great issue.  Thanks!

[nunhgrader]

Wow - a new mag (to me) - thanks for the heads up!