Speaker problem?

[Mark Herrick]

I just received (45 minutes ago!) a JBL E-130 that I put in my Fender "Custom" Vibrasonic. It sounds sweet!

However, I did notice on installing it that inside the vent screen, about a third of the way between the vent hole and the back of the dust cap, there appears to be a thin piece of foam sheet that seems to have deteriorated and a piece of this foam has fallen down and is sliding around on the back of the dust cap.

Is this going to be a problem? The speaker sounds fine when I play.

If this is a problem, how do I go about removing the wayward piece of foam?

Thanks!

------------------

[Ken Fox]

It happens in older Black Widows a lot and does become a problem. It gets into the voice coil gap. I have seen it also stop the speaker movement entirely. With a BW it is simple to remove the basket and clean. With a JBL, not so easy. Eventually it will likely have to be re-coned.

[Brad Sarno]

Maybe you can remove the screen and CAREFULLY stick a vacuum hose in there to suck the debris out of there. Like Ken said, that foam can get into the voice coil gap, melt and then turn to hard goo and make the speaker to bad things. You may want to try and remove the crud and if it doesn't work, you can always get a recone for that speaker.

Brad Sarno

[Mark Herrick]

I was able to get the piece of foam to fall down through the vent hole onto the screen and remove it by taking the label off of the back of the speaker. It wasn't easy but I was able to slip a thin metal ruler under the aluminum label and work it off. (While on my back with the speaker supported over my face between two chairs...) The vent screen was just sandwiched between the label and the back of the speaker. There is still a piece of foam attached inside the vent hole that I am thinking of carefully cutting out. Here's a drawing of what it looks like:



The grey area on the bottom of the circle is the remaining foam. The white area on top is where the missing piece was.

I imagine the foam was meant to keep dust from getting into the back of the dust cap and the voice coil. But it seems like a moot point now since half the foam is gone anyway.

Should I just replace the screen and label and forget about the foam (since I wouldn't be able to put it back in its original position anyway) or should I try to rig another piece of foam, possibly on the back of the speaker?

I'm not particulary interested in spending the money for a recone since the speaker seems to be in good shape otherwise. Why do these things happen to me?...

------------------

[Donny Hinson]

The "foam" was to keep debris out of the speaker. Only problem is, at some point in time, the foam becomes debris itself! Yeah, a piece of foam used for a filter is a dumb idea.

Instead of foam, cut a piece out of your wife's, girlfriend's, or neighbor's old panty-hose, and use that! Just cut a 2" square, and glue it right under the screen. It'll last a long, long time, and it'll never turn to powder like that foam does.

I've even done several "emergency" speaker cone repairs with RTV and panty-hose material...it works great.

[Jim Bob Sedgwick]

Guys, I just discovered I have the same problem with my BW speaker. Question (I'm no tech). Can someone explain how to remove the basket assembly, safely. I do know you have to remove the 3 bolts. Any suggestions as to how not to damage the speaker would be very welcome.

[Mark Herrick]

Here are the instructions from a Black Widow Superstructure Replacement Instruction Sheet that I happen to have:

NOTE: Prior to replacement procedure, clean work area of all metal objects and other debris.

1. With speaker lying face down, remove the three screws on back of the magnet structure with 7/16" nut driver.

2. After screws are removed, lift the magnet structure off the basket frame.

3. Clean the voice coil "gap" before the magnet structure is put on new replacement basket (as shown below). Fold a piece of masking tape over on itself several times, sticky side out, and insert it into the voice coil "gap." Run it all the way around the "gap" several times to remove all particles of metal and other trash before magnet structure is put on new replacement basket.

4. Holding magnet structure in slanted position, gently lower the structure down onto the basket so that it rests inside the magnet structure counter bore, being sure to align the screw holes, and lower the structure down into place. Insert screws and tighten.

I have never pulled the magnet off a BW speaker, but from the illustration (which I couldn't include here) the voice coil gap is on the side of the magnet that faces the speaker basket. Also, in Step 4, the illustration shows one edge of the magnet being positioned against one edge of the basket (the "counter bore" I guess) and then being lowered the rest of the way into position.

Hope this helps!

------------------

[Jim Bob Sedgwick]

Thanks Mark. Maybe I can fumble my way through the process now. I appreciate the help.

[Lee Baucum]

Well, I just pulled my old 1983 Nashville 400 out of the closet for the first time in no telling how many years and guess what! I could see that piece of foam stuck on the back side of the aluminum speaker "dome". I plugged my Mullen into the amp and fired it up and, while the amp worked fine, the tone wasn't there. The lows had a bit of an edge to them and there was no sparkle in the highs.

I followed the instructions Mark posted and removed the magnet from the speaker. (Yes, Jim Bob, you can do it!) There were pieces of foam laying everywhere. I carefully pulled the largest piece of foam away from the aluminum dome and then used a piece of tape to remove the rest of the debris. Everything cleaned up nicely. I also cleaned out the gap, or channel, that is on the magnet. The hardest part was lining up the magnet over the speaker properly. Once I did that, the magnet went right back into place and I replaced the bolts that hold it into place.

I plugged my Mullen back into it and fired it up again. Wow! What a difference. That great sound was back again.

Thanks guys for posting this information. I wonder how many other speakers are out there, in need of this simple overhaul.

------------------
Lee, from South Texas
Down On The Rio Grande

[Jim Bob Sedgwick]

I took my speaker apart, and as Ken Fox stated: There was black goo in the voice coil gap. The stuff had melted on. I couldn't remove all of it but I removed 90%. My sound is back. Then Dave Knight and I took his speaker, (also a Black Widow)
apart. The foam had not melted, but had turned to powder. Thanks guys for all your input on this subject. Hopefully, we've saved a couple of speakers.

[Mark Herrick]

I found the same thing again in my K-130 a couple of days ago when I was doing some speaker swapping between amps. Unfortunately you can't take the magnet off of the JBL's. The K-130 didn't have the screen in back, like the E-130, and I didn't want to remove the label again; too much trouble. So I had to get the foam pieces to slide into the center of the back of the dust cap, then QUICKLY swing the speaker up over my head, allowing centrifugal force to keep the foam pieces in place until the speaker was inverted, when they then fell down through the vent hole onto the slots in the aluminum label. (I mounted the speaker to a piece of plywood slightly larger than the speaker diameter to protect the cone and to have something to hold onto.) Then, using the above mentioned "two chair suspension method", I was able to carefully pull the foam pieces out through the slots with a slim box cutter and a piece of .038 "B" string. Most of the foam was so deteriorated that it crumbled to dust when I removed it.

I imagine now that most old speakers have this problem. If the foam appears to be intact, I would say DON'T TOUCH IT; it is probably so brittle it would fall apart if you did. If you can see it sliding around on the back of the dust cap, it might be a good idea to try to get it out.

------------------