Speaker buzz / rattle in BW 1801-4

[Kipnugget]

Hi all! I recently purchased a 1978 set of Peavey Bass Mark III amp with a 118 cabinet.

The cab emits some buzz / rattle on pretty low volume already. I disassembled everything and found that the noise actually come from the speaker itself. I removed the magnet and cleaned all the gunk I could find. The voice coil and the slot it goes into are really clean, but still the buzz remains. The rest of the cone also looks pristine.

The only other thing I noticed is that when I rotate the magnet in place, it gets stuck in certain points. I tried mounting the magnet in all three possible positions, but no luck. Who knows what else could cause this sound?

Here is a video for reference: https://youtube.com/shorts/QYSbMGDpxP8? ... b7viwUIKNn

[Dookie]

Hi all! I recently purchased a 1978 set of Peavey Bass Mark III amp with a 118 cabinet.

The cab emits some buzz / rattle on pretty low volume already. I disassembled everything and found that the noise actually come from the speaker itself. I removed the magnet and cleaned all the gunk I could find. The voice coil and the slot it goes into are really clean, but still the buzz remains. The rest of the cone also looks pristine.

The only other thing I noticed is that when I rotate the magnet in place, it gets stuck in certain points. I tried mounting the magnet in all three possible positions, but no luck. Who knows what else could cause this sound?

Here is a video for reference: https://youtube.com/shorts/QYSbMGDpxP8? ... b7viwUIKNn

There is a few other things you can try. First gentle push on the cone and see if you feel/hear rubbing. Next remove "1" bolt and push on the cone again. Still rub and get a scraping noise? Put the bolt back in and remove a different one. Repeat. I had 1 woofer that worked great with only 2 bolts holding the magnet down. One other thing I used to do is loosen all three bolts. Push the magnet towards one bolt and tighten that bolt first then the other 2. Check the speaker and repeat with the other 2 bolts. Try to find an area that doesn't rub.

Doug

EDIT to add: Also check the spider. This is the redish round material that holds the voice centered and the woofer as it moves in and out close to the magnet. I've had a section of that come unglued a little and it would flap an buzz like that. Some "super glue gell" type stuff used to reseat it if speaker glue is not available.

[Kipnugget]

Thanks for the reply Doug, you're the man. I had looked at the spider before but not from the right angle, but I just checked again and indeed a portion of it has come loose a tiny bit! I am so happy I finally found the problem

Now, I will check out what exactly "speaker glue" is. I intend to fix this properly.

[Kipnugget]

Ok, so after a bit of googling I found out that a rubberised cyanoacrylate glue or rubberised epoxy glue should be the best options. I see recommendations for Loctite 480 (cyanoacrylate) or 3M DP125 (epoxy). Dear lawd I wasn't prepared for how expensive a little bottle of glue could be

Tomorrow I will continue my quest and see if there are less expensive brands available that make the right type of glue.

[Dookie]

Thanks for the reply Doug, you're the man. I had looked at the spider before but not from the right angle, but I just checked again and indeed a portion of it has come loose a tiny bit! I am so happy I finally found the problem

Now, I will check out what exactly "speaker glue" is. I intend to fix this properly.

What I used to do is use tooth picks to slide under the damaged spider area so I could get the glue in good when I did the repair. There are tooth picks that are flat on an area. I would go in flat then turn it up just a little before the good glued area to get the glue in. Of course you don't want to make it worse but that is a way to get as close as possible to the "good" glued area of the spider with the new glue. Be sure to check all around because sometimes there is a couple of small spots here and there. Let us know how it goes.
Doug

[Kipnugget]

What I used to do is use tooth picks to slide under the damaged spider area so I could get the glue in good when I did the repair. There are tooth picks that are flat on an area. I would go in flat then turn it up just a little before the good glued area to get the glue in. Of course you don't want to make it worse but that is a way to get as close as possible to the "good" glued area of the spider with the new glue. Be sure to check all around because sometimes there is a couple of small spots here and there. Let us know how it goes.
Doug

So I found an alternative to Loctite 480, a rubberised cyanoacrylate glue from Mesa Products in the Netherlands (where I live, so yay). With shipping it was still €18 so almost half the price of Loctite.

Glueing the spider was a bit of a hectic experience. I tried using a needle point syringe but it was so small the glue wouldn't really flow but sputter out a bit. So now there is tiny bits of glue already on the spider drying out so I decided to just use the bottle as best I can to get big drops of glue into the general area, spreading it out with a tooth pick. As I worked I could feel the glue already hardening so I had to be quick to clamp it. The instructions said to press down or clamp for 30-60 seconds and let it harden for 8 hours. I just let the clamps on overnight to be sure.

Now for the results........ The noise is almost gone. ALMOST The volume has gone down 90-95%, but still some buzz remains. Either the spider still isn't 100% glued down or something else was and still is rattling around.

So I will continue taking hints and advice on what could still be making noise.

[Kipnugget]

In the mean time I thoroughly inspected the spider. I checked if the edge was coming loose anywhere, which it wasn't. But I also checked the opposite side and if I flexed the spider at certain points, it looked like some parts of the edge were moving a tiny tiny bit and thus are not glued down 100%.

I'm not sure if I am seeing ghosts or am on to something. I have half a mind to just completely loosen and reglue the entire spider.

[Kipnugget]

Update on the speaker repair: I tore loose the entire spider except for the already re-glued portion. I carefully glued it back together making sure to get glue on 100% of the contact surface between the spider and the frame, so there would be nothing loose enough to vibrate.

Result: still the same noise. SMH I’m now taking it to a repair place in hopes that an expert can find the problem.

[Dookie]

Update on the speaker repair: I tore loose the entire spider except for the already re-glued portion. I carefully glued it back together making sure to get glue on 100% of the contact surface between the spider and the frame, so there would be nothing loose enough to vibrate.

Result: still the same noise. SMH I’m now taking it to a repair place in hopes that an expert can find the problem.

Any chance at all it is before the speaker? Issue with the amp or the bass itself (fret buzz etc?) ? Had a chance to try a different speaker? Let us know what you find out regardless. It may help out someone reading this in the future.

Doug

[Kipnugget]

Any chance at all it is before the speaker? Issue with the amp or the bass itself (fret buzz etc?) ? Had a chance to try a different speaker? Let us know what you find out regardless. It may help out someone reading this in the future.

Doug

I am 99% sure it is the speaker itself. There actually is a problem with the amp, an audible hum from -probably- the transformer, and yes there is fret buzz, but both sound very much different than the speaker noise. If I tap on the speaker cone with my finger (in just the right spot) I can faintly hear the noise under the thud or oomph sound.

For future reference:

• I have tried the speaker mounted in the cab or laying flat on top of it, no difference.
• I have rotated the magnet in all three positions possible, no difference.
• After glueing back the loose portion of the spider the noise reduced in volume.
• After re-glueing the rest of the spider the noise volume is pretty much back to original

I will add any other findings here as well, even if I end up replacing the basket or even the entire speaker. It would be sad if I would not be able to fix it in the end, but at the very least I know I can turn the speaker into a sick 18" side table or something