B&C 15" Neodymium Driver Rear Chuffing HELP!

How are you testing it? If in free air i'd say it's probably normal.
If so try it in a box before starting to worry.
There was a thread on here a while back where I mentioned a loose coil on the former can cause problems (I've personally experienced this). That driver showed no coil rub when pushed, just had a rattle at certain frequencies.

But does the Fane have a vented magnet assembly?
The JBL VGC models used to be noisy when pushed in free air so try it in a box first. The vents on that B&C seem pretty small so they'll make some chuffing sounds.

So it is a 3" coil, relatively light cone, high efficiency woofer. Looked at the spec sheet and the Xmax is +/- 4mm.

Personally I wouldn't have said that the voice coil cooling arrangement on this woofer was a particularly clever design. Not surprised that you get "chuffing".

Look at the size of each of the cooling vents...like trying to force air through a drinking straw.

Sort of reminds me in concept to a JBL 2226, where instead of having a central cooling vent they have four smaller vents (at least bigger than the tiny holes on this driver) designed to allow heat to be taken from right up close to the voice coil. Great in principle, but actually leads to "hot-spots" on the voice coil where the vent "cut away" is.

Would love to see what is actually going on, hidden under the cast frame on this neo B&C.

Earplug wrote: I don't know how good an idea it is to "crank" any speaker if not in an enclosure. One "speaker guy" I knew (Mike Cotter, RIP) definitely said that it was a no-no.

I understand the driver isn't getting the air pressure resistance from the cabinet but I'd love to know more to the why of this... and, "cranked" was an over exaggeration, I wouldn't be taking the driver anywhere near max capacity. It was meant more as in slightly louder than just being on for a basic test. Most drivers today can take all sort of abuse I don't see how much of a short test out of cabinet can be a serious no no, but I'm open to more insight. Edit: also, yes, the sound would be rubbish, so not much good as a test of the quality of the speaker.

@APC321. I'll make sure to dissect it when it fails and get some pictures up.

@Wikl109. That's a good point, the fane is vented but it's the typical centre hole. Sovereign Pro 15, nothing fancy like what these B&C are trying to do.

@Singingfish. Yes, I'm hoping to get tested in the dampened cab tonight, didn't manage last night, ran out of time.




Edited by mitchiemasha - 06 October 2022 at 12:47pm