JBL LE14-1, Refoaming Turned Up an Issue

[Corbin Gross]

Hey, guys.

So I'm refoaming a JBL LE14-1 for a friend and have run in to an issue.

When I started the inner lip of the foam-job, I noticed that the cone had settled way below the zero position, and was kind of "stuck down". Almost kind of wedged down, just slightly.

I didn't think anything of it, until I started the outer lip and tried to center the cone with the 30hz test tone.

It's giving me sort of a buzzing/rattling noise. Sounds kind of like the engine noise outside of an older but well maintained car. With all those belts whipping around and the hydraulic lifters clacking away. But just a little bit.

It's not the usual off center, scraping noise. I can nudge it a bit and hear the voice coil really rub. But this is like a baby VC rub.

It sounds to me like maybe the very bottom/back side of the VC is maybe bent and rubbing just a little?

What do you guys think? You ever run it to this?

Thanks, all. Your help is much appreciated.

 

[leesonic]

It could be the back of the voice coil bottomed out at one time, and got bashed against the backplate. If the magnets were easily removable like the ones on my L100 woofers, you could investigate further. Otherwise, it might be possible to "massage" the voice coil former back into shape by pushing the cone out from the rear, it helps if there is no surround on here (sorry if you've already reformed them). Shimming them might also help, since the shims might also help reshape the coil former.

Hope this helps,

Lee.

 

[Bob Orme]

Hey, guys.

So I'm refoaming a JBL LE14-1 for a friend and have run in to an issue.

When I started the inner lip of the foam-job, I noticed that the cone had settled way below the zero position, and was kind of "stuck down". Almost kind of wedged down, just slightly.

I didn't think anything of it, until I started the outer lip and tried to center the cone with the 30hz test tone.

It's giving me sort of a buzzing/rattling noise. Sounds kind of like the engine noise outside of an older but well maintained car. With all those belts whipping around and the hydraulic lifters clacking away. But just a little bit.

It's not the usual off center, scraping noise. I can nudge it a bit and hear the voice coil really rub. But this is like a baby VC rub.

It sounds to me like maybe the very bottom/back side of the VC is maybe bent and rubbing just a little?

What do you guys think? You ever run it to this?

Thanks, all. Your help is much appreciated.

It could be one thing or a combination of things. The spider could be sagged and stretched enough to cause problems with the voice coil alignment. The bottom of the voice coil former could have hit the pole piece and folded a small section of it inward. If the voice coil former is Nomex (I think it is on that woofer), it could have bubbles in it causing the voice coil to rub.

You should be able to see any spider problems - it is supposed to be flat. To see possible voice coil former problems, the dust cap has to be removed.

 

[Corbin Gross]

Thanks, guys.

So it sounds about like what I expected as well.

I'll talk to the guy before I take off the dust cover, but that's what I figured would be the next step as well.

I'll let you guys know how it turns out.

Thanks!