Test baffle and driver Break-in

[NyxOne]

Hi,

i recently bought new drivers and test equipment. I'm now ready to "break-in" my driver and test them. Before doing so, i would like to ask you a few simple questions that I've not been able to answer myself.

1. Driver break-in : I've read that a good practice for driver "break-in" is to run them at full x-max for an a day but frankly i'm afraid of over driving them. Could someone explain me his procedure ?

2. Test baffle : I'd like to know what size you would recommend for a test baffle and if there's implication on the resulting measurement (e.g. small baffle vs large one) ?

Thanks.
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Charles D.

[jkrutke]

Not too much to explain, but if you want to protect the drivers, do a checkup 15 minutes after the break-in starts. If the magnets are warm to the touch at this point, it might be a good idea to set a lower level. Most high end drivers don't have this heat dissipation problem but some cheap stuff does. Break in face down, with enough clearance for the surround and airflow.

Heheh, I've "broke in" some cheaper drivers without doing that heat check, only to check on them 8 hours later and find a funky burnt electronics smell with no cone movement. :B

For the baffle, obviously, larger is better. The larger you make it, the further back you can put the mic before dipole cancellation becomes an issue. Though at some point, it doesn't matter because room reflections become the bigger issue. Mine is about 3.5 feet by 5 feet, double MDF thick. There's a page on my site called "soundeasy setup" or something with a bit more info.

[tpremo55]

Not too much to explain, but if you want to protect the drivers, do a checkup 15 minutes after the break-in starts. If the magnets are warm to the touch at this point, it might be a good idea to set a lower level. Most high end drivers don't have this heat dissipation problem but some cheap stuff does. Break in face down, with enough clearance for the surround and airflow.

Heheh, I've "broke in" some cheaper drivers without doing that heat check, only to check on them 8 hours later and find a funky burnt electronics smell with no cone movement. :B

For the baffle, obviously, larger is better. The larger you make it, the further back you can put the mic before dipole cancellation becomes an issue. Though at some point, it doesn't matter because room reflections become the bigger issue. Mine is about 3.5 feet by 5 feet, double MDF thick. There's a page on my site called "soundeasy setup" or something with a bit more info.

John,
I've read your site a number of times thanks for all the great info. In fact, I was there just last night looking at your baffle setup again. If I could add to Charles' line of questioning, do you measure T/S in SE with the drivers in the baffle - or face down on golf tees? Also, you have mentioned that you calibrate with the mic cable and speaker wire - how do you go about that?

[jkrutke]

John,
I've read your site a number of times thanks for all the great info. In fact, I was there just last night looking at your baffle setup again. If I could add to Charles' line of questioning, do you measure T/S in SE with the drivers in the baffle - or face down on golf tees? Also, you have mentioned that you calibrate with the mic cable and speaker wire - how do you go about that?

The initial impedance is usually taken free air, no baffle. (Doing it face down would throw things off due to the restriction of the close surface) I can do it in the infinite baffle also, but it can affect the Fs by a few Hz. Then a delta compliance Vas impedance is taken in an adjustable volume box.

Normal people would send everything to a calibrator, wire, mic, preamp and all. I'm lucky enough to have a few contacts in the industry and I did it different. Basically, I sent a tweeter to a large anechoic chamber and had it measured with some decent equipment, countersunk into their baffle. I actually sent a whole baffle insert. It was then sent back to me, adapted to my baffle and measured here, and I wrote my own compensation file until I got the same results. What was sickening is after all that, the generic ECM8000 calibration file I was using hardly changed at all, and for the most part all that calibration work was a waste of time.

[ttan98]

John K.,

I have a query under Seas ER18 design thread, I am looking forward to hear your opinion.

[NyxOne]

Not too much to explain, but if you want to protect the drivers, do a checkup 15 minutes after the break-in starts. If the magnets are warm to the touch at this point, it might be a good idea to set a lower level. Most high end drivers don't have this heat dissipation problem but some cheap stuff does. Break in face down, with enough clearance for the surround and airflow.

Heheh, I've "broke in" some cheaper drivers without doing that heat check, only to check on them 8 hours later and find a funky burnt electronics smell with no cone movement. :B

Thanks i've read your trick about "golf tees". I wouldn't have though of it by myself. My new drivers are HiVi d6.8 which i have for a good deal ... to find out that some unit where behaving strangely (Ragged impedance). That's why i actually did the "break-in" process. I've used a 20hz at what seem to be full x-max but after an hour the drivers were warm and the room had a strange odour so i stopped. I guess i was asking to much from them*.

For the baffle, obviously, larger is better. The larger you make it, the further back you can put the mic before dipole cancellation becomes an issue. Though at some point, it doesn't matter because room reflections become the bigger issue. Mine is about 3.5 feet by 5 feet, double MDF thick. There's a page on my site called "soundeasy setup" or something with a bit more info.

WOW!!! That must a pain in the a** to move around. I'll go read that on your website. Thanks.

[...] he generic ECM8000 calibration file I was using hardly changed at all, and for the most part all that calibration work was a waste of time.

I guess what it gave you is certitude / no doubt about your results. Personally i find it priceless!

Thanks.
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Charles D.