Speaker farting out distortion questions.

[mchn13]

Had a speaker cab start making a noise every time I did a pronounced palm mute on a low note. Thought it was maybe a blown speaker (v30’s/engl cab), so I brought it home to maybe grab a couple new speakers this week, and get it back in action. Story short, pulled a couple speakers, and they’re old, but cones are tight, no noise from moving the cone.
Tried my other engl cab that I turned into a 2x12, and same shit. I feel there’s no way I’ve blown 6 v30’s on the same day with a 50 watt head...?
The only other time I’ve experienced this is when I was using a different boost pedal, and a similar sound. My question: could it be the dimebucker at band volume just being dirty on the low end? I was really trying to get along with this pickup and just use my eq on the amp to get it to work.
I won’t be able to try my Jackson with a nazgul in it til next Friday, so wanted to see if anyone had any experiences like this. A pickup would be a lot cheaper than four speaks lol.

 

[maddnotez]

I had the same thing happen with my Uberschall. Just had to turn the bass down. Maybe something going bad inside the amp?

 

[HellraiserJohnny]

I had this on a few of my Marshall cabs, found out it was loose screws the hold the back cover on. Tightened them and it stopped for about 6-8 months then started again. So we took the back off completely and ran a silicon bead all the way around the inside of the cab where the back fits in. Let it dry completely!
Makes an airtight seal. Never happened again in over 15 years.

 

[Oblivion DC]

Two things I can think of. Make sure the speakers are screwed in tight enough and run a screw through the back and into the brace/support/strut.

 

[mchn13]

Thanks fellas. Gonna inspect it and try some of this this week.

 

[mchn13]

I had the same thing happen with my Uberschall. Just had to turn the bass down. Maybe something going bad inside the amp?

It does get better if I dial the bass down, but it’s an Evh 50 watt. Doesn’t have the low end that my Vht had even... I’m starting to suspect the pickup more that I think about it. Gonna try and a/b guitars first before I start dismantling shit. The week before I was using the jackson with the nazgul and don’t remember hearing this.

 

[RaceU4her]

I had this on a few of my Marshall cabs, found out it was loose screws the hold the back cover on. Tightened them and it stopped for about 6-8 months then started again. So we took the back off completely and ran a silicon bead all the way around the inside of the cab where the back fits in. Let it dry completely!
Makes an airtight seal. Never happened again in over 15 years.

ive had the same problem with a few of my cabs and this is what i did as well.

 

[Racerxrated]

I had this on a few of my Marshall cabs, found out it was loose screws the hold the back cover on. Tightened them and it stopped for about 6-8 months then started again. So we took the back off completely and ran a silicon bead all the way around the inside of the cab where the back fits in. Let it dry completely!
Makes an airtight seal. Never happened again in over 15 years.

ive had the same problem with a few of my cabs and this is what i did as well.

Whenever I've gotten a used cab I've always made sure all the screws were tight...and every single cab had at least 2-4 not tight at all. I've also used the silicon trick and that will make a cab push out a much tighter response if that is what you want.

 

[ChurchHill]

Just make sure you don't over-tighten the speaker mounting screws. If you do, you can risk bending the frame if it's stamped metal (as opposed to cast frames like an EVM, etc.). They should be tight and all should have similar amounts of torsion.

FWIW, every time I've heard that noise, it's been a loose back panel. The silicon is a good fix. I've seen weather strip used, too. Also, if there's a center support, make sure it's making good contact with the back panel. If not, it can cause that rattling, too. I usually add a layer or two of rubber drawer liner, just to make sure it's tight and doesn't vibrate.