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Driver burn/break-in discussion

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Tonskulus View Drop Down
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    Posted: 10 January 2019 at 6:16am
Hmm, couldn't find any threads about that. 
Anyway I had to start this thread because I measured some drivers new vs. used.

As example, here is Tangband 4 inch bass driver (rubber surround) and for me it looks serious change in parameters.   Burn-in method was: 20Hz, 15min, cone excursion close to Xmech.  I let the driver cool off about 1 hour before measurement.

Measuring tools: REW,  10ohm series/sense resistor, low impedance source/amplifier. 0.8Volt signal.


Orange: new out of box   
blue: broken-in

Fs from specs: 55Hz

Will do another measurement today, after 24hours of "resting". Anyway if Fs drops from 60Hz to 40Hz, that is a lot! Isn't it?
I'm going to put these drivers in cabs to measure real spl response, and of course do some comparative listening.  It's just.. I calculated my cabs (smallish ported boxes) using parameters from manufacturer specs, which were pretty close to those measured from brand new driver.







Edited by Tonskulus - 10 January 2019 at 6:20am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddymendez Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 7:56am
Edit :)

Edited by freddymendez - 10 January 2019 at 11:21am
120-140 bpm, pianos and bass.
diesel, the fuel of professionals.
mendez/manchester
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pasi Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 8:37am
Couple of hours is more than enough for T-S measurements and you'll find out that what is said in the spec sheet includes around 10% deviation, or sometimes even more.

And yet, makes hardly any difference in reality

For end user, no burn in is ever needed.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 8:49am
Originally posted by freddymendez freddymendez wrote:

Burn it in for 100 hours or it might explode when you use it

Why is that? Cannot find any reason why would they explode without burn-in procedures. 
If it would happen, I would say it has been faulty driver out of the box. Or user error (driving too hard, no matter if its burned in or not).  Some kind of myth it is, because I have never seen any manufacturer recommending burn in process.

Never heard such a things happen tho.. when ever I put new drivers in, they do what they are supposed to do no problems playing to the maximum levels. 




Edited by Tonskulus - 10 January 2019 at 8:50am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pasi Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 8:50am
It's Freddy. Don't take him too seriously this morning. I guess he was bored or drunk :) Recommended using mustard as a sealant on cabinets too :D :D
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddymendez Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 9:18am
Edit :)

Edited by freddymendez - 10 January 2019 at 11:18am
120-140 bpm, pianos and bass.
diesel, the fuel of professionals.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 10:23am
That is quite a big shift, what is the stated CMS on that driver?  

It can vary quite a lot from driver to driver, this is for a B&C 15TBW100, they sounded quite different after run in it was quite noticeable,  some drivers there is not so much difference.  

Run in signal was 25% duty cycle 20Hz sine wave to approx xmax

15TBW100
New Fs=53.16Hz
1 hour Fs=49.12Hz
2 hours Fs=43.07Hz
3 hours Fs=40.38
3 hours / 30 mins rest Fs=42.39
4 hours Fs=39.03
5 hours Fs=39.03
5 hours / 24 hour rest Fs=51.81 , but after a 5 minute run Fs is back to 40.24Hz

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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 10:53am
Originally posted by Timebomb Timebomb wrote:


Run in signal was 25% duty cycle 20Hz sine wave to approx xmax

15TBW100
New Fs=53.16Hz
1 hour Fs=49.12Hz
2 hours Fs=43.07Hz
3 hours Fs=40.38
3 hours / 30 mins rest Fs=42.39
4 hours Fs=39.03
5 hours Fs=39.03
5 hours / 24 hour rest Fs=51.81 , but after a 5 minute run Fs is back to 40.24Hz

Havent excursion changed drastically from the beginning to the end?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 3:38pm
Not a lot with 20Hz
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 28 January 2019 at 6:38pm
Remember the burn-in of my newly mounted 18NW100s some time before. We started slow on the gig, and in some eight hour period, we put that thing....
The sound was different. Definitely more bass under 50Hz after that.
I think it has been said that first hour is most critical, then the difference gets negligible. With this hi-fi breaking in for 48hours of pure sine wave "pedal to metal" I would rather worry about SPENDING life expectancy of those surrounds and spiders...
Nikon and Canon people should not be married to each other. Why did you let this happen?
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