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Old 6th October 2013, 03:47 PM   #111
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Quote:
Originally Posted by woofertester View Post
I regularly do both just to see the before and after. For design you use the after break-in parameters.
As a point of discussion, I have a 12 inch Tantric woofer that has an excursion in excess of 3 inches pk-pk. At rest the Fs is 32 Hz. At full excursion Fs is 17 Hz. It takes a couple of minutes for the surround to cool down but eventually the Fs returns to 32 Hz when using the WT2.
This is why we make the WTPro. Most people have no idea how different a speaker is at Xmax compared to at rest.
I had seen in lots of you tube videos of speaker production factories like Eminence & many others. They randomly test raw drivers just after every production batch before packing. They do not run them till break in.
I have few questions here....
(1). What is the accepted industry standard or in other words ... which would be considered the accurate or actual t/s specs of any driver as to be specified by the manufacturer in their spec sheet , will it be after break in or before break in ???? .
(2). What are the conditions required when testing thru WT2 .... I mean driver mounted or unmounted, driver positioning & placement during the test, environment criteria ..... in room, outdoors, anechoic chamber etc. Any specific environmental conditions as to room temperature or relative humidity.
Vivek
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Old 9th October 2013, 07:10 AM   #112
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For a manufacturer, they want to know if the driver was built correctly. The test is a "pass/fail" and not how it will play in your design. You break in and test so that you know how it will play in your design.

Break-in will not radically change the volume of your box nor the tuning frequency if it is a vented system. You break in the speaker to minimize the errors in the final tuning.

Delta mass requires that the speaker be horizontal unless you stick the mass to the speaker which can cosmetically ruin some speakers.

You must not set a speaker on its magnet structure if it is vented. This will cause the Fs/Qts to become wrong for the measurement. We recommend that you suspend the speaker with bungee cords. This decouples the speaker from vibrations of open/close door, walking, etc. See this

woofertester.com

If you have a concrete floor, you can set the speaker on blocks that allow air to get to the vented pole piece. I use scrap wood from cabinet projects.
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Old 9th October 2013, 04:19 PM   #113
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Quote:
Originally Posted by woofertester View Post
For a manufacturer, they want to know if the driver was built correctly. The test is a "pass/fail" and not how it will play in your design. You break in and test so that you know how it will play in your design.
Forget the manufacturers. What if anybody build their own driver ?.
What if I build or fabricate a raw sample prototype driver from scratch ...... motor assembly to frame to cone/spider/voice-coil/dust-cap. Driver is ready with unknown parameters. To know about its t/s values kindly advise, What next ?. What shall I do next ......... ??? , run a break in before measuring thru WT2 ???.
Vivek
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Old 9th October 2013, 11:40 PM   #114
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It is always advisable to break in a driver before measuring. You will be using it broken in for years, so you should measure it broken in.

When I break in a driver, I use a WT2 line output set at 15 Hz. I use an amplifier with a volume control. I adjust the volume for full Xmax excursion. I use a laser pointer aimed at the dustcap to eyeball the measurement of excursion. I also listen for the voice coil tapping the back plate and adjust to just below the tapping sound.

I run the speaker at Xmax for at least 1 hour. I let the speaker cool for at least 1 hour. Then I test the speaker for T/S parameters.

If I have time, I will run the speaker at Xmax 8 hours and let it cool over night.
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Old 13th October 2013, 02:07 PM   #115
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Quote:
Originally Posted by woofertester View Post
It is always advisable to break in a driver before measuring. You will be using it broken in for years, so you should measure it broken in. When I break in a driver, I use a WT2 line output set at 15 Hz. I use an amplifier with a volume control. I adjust the volume for full Xmax excursion. I use a laser pointer aimed at the dustcap to eyeball the measurement of excursion. I also listen for the voice coil tapping the back plate and adjust to just below the tapping sound. I run the speaker at Xmax for at least 1 hour. I let the speaker cool for at least 1 hour. Then I test the speaker for T/S parameters. If I have time, I will run the speaker at Xmax 8 hours and let it cool over night.
Does this rule also applies for fixed edge full-range, lower & upper mid-range speakers ?. How would anyone determine the break in frequency for fixed edge full-range & mid-range drivers, and for how long ?

Last edited by SIDEWINDER 18X; 13th October 2013 at 02:13 PM.
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Old 13th October 2013, 05:10 PM   #116
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Originally Posted by SIDEWINDER 18X View Post
Does this rule also applies for fixed edge full-range, lower & upper mid-range speakers ?. How would anyone determine the break in frequency for fixed edge full-range & mid-range drivers, and for how long ?
I use 15 Hz because it is below Fs and at 15 Hz the speaker is easier to excurse with the least power and the sound does not destroy your hearing. Try being in a room with a speaker moving 3 inches peak to peak at 1kHz. At 15 Hz the speaker will move much more like a piston than at 1 kHz. You are breaking in the suspension and not the cone. So, a frequency where the cone is not breaking up is preferable in my opinion.

You can use any frequency you wish that allows you to break in the speaker. I choose what works for me.

The spider is the part that changes the most. For a speaker whose compliance/Vas is dominated by the surround, break-in will affect the speaker less.

There are no industry standards for what you have been asking. There are only some accepted practices and knowledge gained by study and trial and error.

There is a school of thought that holds forth that the speaker is not going to be in a much different box after break-in than before. This will be true for a closed box system. Maybe not so much for a vented box system.
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