Question about buzzing EV12L speaker ... coil rub?

[amplifiednation]

Hey guys, I've been searching around the net to try to figure out what this odd sound is in one of my speakers.

I have a vintage EV12L that is making a buzzing/rattling sort of sound on most notes. It literally sounds like there is something that is bouncing around inside the speaker.

I've tried three different cabs, different wiring, still the same results.
Is this voice coil rub?

I got the speaker used a few months ago and it's got a date on it showing a "good" test from a speaker warehouse in 12/10. It's never sounded right though.

I can't figure it out. Voice coil rub? Do I need a recone? What is it? I'm pretty good with the internet, I'm not sure why I can't figure this out.

Any help would be greatly appreciated.

[David Root]

Could be. I had an old Altec that had a very slight case of it. I rotated the speaker in the cabinet until it stopped. I think that if the misalignment is small enough doing that can get the rub point at 12 noon where the coil weight is just enough to center it enough that it stops rubbing. I know that sounds dumb, it shouldn't move in the magnet's field, but whatever it was doing that fixed it.

First I tried just turning the cab upside down and that almost fixed it. If that doesn't fix it, try www.merrenaudio.com in San Diego. He claims to be able to fix that kind of thing frequently (not always) without doing a recone, which has obvious advantages.

[amplifiednation]

Thanks David. So do you suggest that the buzzing could in fact be coil rub?

Would there be any physical symptoms of the speaker?

I feel like it would probably be cheaper just to buy a new one of these than get it repaired...it was only like $125. That's a lot for a speaker that doesn't sound good.

[selloutrr]

I've had a similar problem a couple times and under close examination it's been caused by once a small screw and another time a washer.
The magnet picked up it up somewhere I didn't notice it (probably should have looked before I installed it.
it would rub against the basket and cone during speaker travel.
I had to really get in and feel for it with my finger.
If you think it's rubbing.
take the speaker out place it on the magent looking up at you and gently exercise the speaker listening and feeling for rubbing. You will be able to tell if it's rubbing. Keep in mind while testing if you are off center you can force it to rub so becareful and take your time.

[amplifiednation]

I've had a similar problem a couple times and under close examination it's been caused by once a small screw and another time a washer.
The magnet picked up it up somewhere I didn't notice it (probably should have looked before I installed it.
it would rub against the basket and cone during speaker travel.
I had to really get in and feel for it with my finger.
If you think it's rubbing.
take the speaker out place it on the magent looking up at you and gently exercise the speaker listening and feeling for rubbing. You will be able to tell if it's rubbing. Keep in mind while testing if you are off center you can force it to rub so becareful and take your time.

You don't know how bad I want it to be a washer or a screw...I looked around pretty well and can't find anything that shouldn't be there.

What does rub feel like? I can feel friction while pushing the speaker in and it seems like it's catching on something when it moves out. Is that rub? Where does it come from?

[selloutrr]

the easiest way to explain it would be for you to try the same test on a know good speaker. once you have a feel for a good speaker it'll tell you fast if it's not correct.

bummer it's not a piece of something

[amplifiednation]

I have tons of other speakers...all mounted in cabs. uggh. good thing tomorrow is saturday. thanks

[David Root]

I never thought of that, that actually sounds more likely than voice coil rub.

So how do you confirm that and then get the stuff out of the speaker?

[Structo]

Yeah, you shouldn't feel any friction when you press down on the cone.
If you use equal pressure and feel something then it is most likely coil rub.

Eventually it can wear through the winding and the speaker will stop working.

Does the magnet look well centered?

[bluesfendermanblues]

I have a EVM12 that had a similar rub problem.

was able to loosen the screws holding the magnet and move the magnet a little bit by gently hammering a couple of times after which I tightened the screws.

[amplifiednation]

Yeah? Maybe I will try that.

The coil is rubbing. It has been confirmed, and its rubbing badly. This explains the good deal I got on the speaker.

I'm gonna try moving the magnet and if it doesn't work I'm going to cut the center out of the speaker and see if i can reform the coils to not rub. Should be a fun three week process. Too bad there's no "speaker garage". I will post pics and instructions if I can fix it.

[Structo]

Yeah, but which way do you move the magnet?

[Gibsonman63]

I have done a couple of drop in kits. Maybe you can do some of the process in reverse. You could carefully cut out the dust cover to get access. Then with a strong light and some good magnification, you should be able to look down the gap to see where it is rubbing. The shims that come with the drop in kits are nothing more than a flexible sheet of plastic cut to match the circumferance of the gap. Maybe you can shim it or at least shim the side with the rub. I am not sure how to soften the cone up to reshape it, but maybe someone can chime in with that part.

Once you are done, order a new dust cover and glue it back in place.

BTW, on the musicelectronics forum, there are several guys that recone speakers as well as a few threads on it. You may have a look there as well for ideas.

[amplifiednation]

I took the speaker to a friends house yesterday who's extremely experienced with all things amps/speakers and we confirmed the coil was rubbing.

Gibsonman, he had the exact same advice as you, which was to cut off the dust cover and try to shim out the coil away from the magnet. So I went for it last night.

I can't believe how badly the coil is catching on the magnet Check out these pics. There are some indentations on the outside of the cone which makes me think something either hit the speaker pretty bad or something was leaning on it.

I'm really bummed, I was psyched for this speaker. Maybe I can fix it.

[Teleguy61]

Ouch!
Not pretty.
I understand it's not a difficult process,
haven't done it myself, but here are a couple sources:

http://www.soundspeakerrepair.com/speak ... p-in+Kits/

http://www.reconingspeakers.com/product ... econe-kit/

Good luck.
George