212AV with obnoxious buzz, can’t trace, HELP,,,

[Ringhammer]

Are you able to access the port tube, and apply pressure to it while playing that A to see if the buzzing stops? I have a cab (different brand) that is making a buzz at specific "D" frequencies, and I've traced it to the port tube. The fix will be to remove the port tube and re-install with fresh sealant, but my cab has a metal grill held on with about 20 screws so it is easy (although tedious) to remove the grill. I don't know how Ampeg attaches the grill on their cabs

The port tubes are screwed in and are tight, I have righted ever screw I can find, so I’m pretty sure it’s going to come down to bracing. Hoping following the above suggestions will fix. If it is a delaminating issue, then I’m not sure what the fix will be. Since it seems simply pushing on the cabinet in various random spot seems to alleviate it, I’m feeling confident it’s going to turn out to be bracing.

 

[byacey]

If the panels are de-laminating, it would be simpler to build a new box. If you go that route, I would use Baltic Birch, and beef up the baffle board, too.

 

[FenderB]

Identifying the cause of the problem helps with making suggestions that help the OP. Just randomly replacing parts is not going to help.

Didn't say anything about "randomly" replacing parts.

 

[FunkHead]

Didn't say anything about "randomly" replacing parts.

I would just replace the part that's buzzing.

 

[FenderB]

I would just replace the part that's buzzing.

That's a start.

 

[Ed Byrnes]

I had noise/vibration also. I tracked it down to a loose "cross bar" support in the cab. You have to remove the speaker and see if you can wiggle it. I used some foam and duct tape and wood glue...very inelegant...hahahaha, but it worked. Cab is rock solid now. Picts below...

 

[Ringhammer]

Can’t wait to get to this on the weekend, it’s sounding more and more like the front to back brace.

 

[CharlieFla]

I think I solved my cab’s problem. The internal cross-member/brace (which runs from the baffle to the internal rear wall) was the culprit. Oddly enough, the brace did not feel loose when I tried to manually apply pressure. But the horrendous rattle was directly in the area where the brace joined the baffle. Healthy suspicion beating a scientific diagnosis, I got to work.

Here’s my fix:
1. I removed the speakers, the horn, and the rear jack plate. The horn and the rear jack plate probably didn’t need to come off, but it gave me a little more light and access to the innards of the cabinet. [Note to self: “Innards” is a candidate for a good band name.]
2. I drilled a pilot hole from the exterior of the cab into the center cross-section of the brace. I had to guesstimate the best spot to drill.
3. I inserted a VLS (very large screw), a washer, and a finish washer into the hole.
4. I liberally applied some wood glue to the attachment points where the brace met the baffle and the rear wall. I don’t know how the drunken elves at Ampeg attached the brace during construction, but the brace in my cab did not appear to be glued, stapled, or screwed. I think they relied on reputational inertia.
5. I re-assembled everything. There are so many nuts and screws.

Success. No more nasty rattle. [Note to self: “Nasty Rattle” is a candidate for a good band name.]

 

[Mastermold]

I think I solved my cab’s problem. The internal cross-member/brace (which runs from the baffle to the internal rear wall) was the culprit. Oddly enough, the brace did not feel loose when I tried to manually apply pressure. But the horrendous rattle was directly in the area where the brace joined the baffle. Healthy suspicion beating a scientific diagnosis, I got to work.

Here’s my fix:
1. I removed the speakers, the horn, and the rear jack plate. The horn and the rear jack plate probably didn’t need to come off, but it gave me a little more light and access to the innards of the cabinet. [Note to self: “Innards” is a candidate for a good band name.]
2. I drilled a pilot hole from the exterior of the cab into the center cross-section of the brace. I had to guesstimate the best spot to drill.
3. I inserted a VLS (very large screw), a washer, and a finish washer into the hole.
4. I liberally applied some wood glue to the attachment points where the brace met the baffle and the rear wall. I don’t know how the drunken elves at Ampeg attached the brace during construction, but the brace in my cab did not appear to be glued, stapled, or screwed. I think they relied on reputational inertia.
5. I re-assembled everything. There are so many nuts and screws.

Success. No more nasty rattle. [Note to self: “Nasty Rattle” is a candidate for a good band name.]

View attachment 4297211 View attachment 4297212

Note to self: “Reputational Inertia” is a good band name.

 

[byacey]

I think I solved my cab’s problem. The internal cross-member/brace (which runs from the baffle to the internal rear wall) was the culprit. Oddly enough, the brace did not feel loose when I tried to manually apply pressure. But the horrendous rattle was directly in the area where the brace joined the baffle. Healthy suspicion beating a scientific diagnosis, I got to work.

Here’s my fix:
1. I removed the speakers, the horn, and the rear jack plate. The horn and the rear jack plate probably didn’t need to come off, but it gave me a little more light and access to the innards of the cabinet. [Note to self: “Innards” is a candidate for a good band name.]
2. I drilled a pilot hole from the exterior of the cab into the center cross-section of the brace. I had to guesstimate the best spot to drill.
3. I inserted a VLS (very large screw), a washer, and a finish washer into the hole.
4. I liberally applied some wood glue to the attachment points where the brace met the baffle and the rear wall. I don’t know how the drunken elves at Ampeg attached the brace during construction, but the brace in my cab did not appear to be glued, stapled, or screwed. I think they relied on reputational inertia.
5. I re-assembled everything. There are so many nuts and screws.

Success. No more nasty rattle. [Note to self: “Nasty Rattle” is a candidate for a good band name.]

View attachment 4297211 View attachment 4297212

Good job! I hope you used PL on the joint; it's not as brittle as carpenters glue.
If you want to beef up the gluing surface area, you can do something similar to this:

 

[Ringhammer]

Yes, this may be what’s happening with my cabinet as well. I actually randomly thumped on the back / center of mine and actually hear a quick rattle/vibration. I’m pretty sure this will be the solution to my problem as well.

I’ll follow up this weekend and let you know if the brace is the problem in mine as well.

It will be a huge relief if it’s this and not a de-lamination issue.

 

[agedhorse]

This is why troubleshooting is so important. Once you identify the cause of the problem, the fix is much easier and way more effective than simply “replacing old parts” which in this case would have done nothing but cost you money.

 

[jeff7bass]

I think I solved my cab’s problem. The internal cross-member/brace (which runs from the baffle to the internal rear wall) was the culprit. Oddly enough, the brace did not feel loose when I tried to manually apply pressure. But the horrendous rattle was directly in the area where the brace joined the baffle. Healthy suspicion beating a scientific diagnosis, I got to work.

Here’s my fix:
1. I removed the speakers, the horn, and the rear jack plate. The horn and the rear jack plate probably didn’t need to come off, but it gave me a little more light and access to the innards of the cabinet. [Note to self: “Innards” is a candidate for a good band name.]
2. I drilled a pilot hole from the exterior of the cab into the center cross-section of the brace. I had to guesstimate the best spot to drill.
3. I inserted a VLS (very large screw), a washer, and a finish washer into the hole.
4. I liberally applied some wood glue to the attachment points where the brace met the baffle and the rear wall. I don’t know how the drunken elves at Ampeg attached the brace during construction, but the brace in my cab did not appear to be glued, stapled, or screwed. I think they relied on reputational inertia.
5. I re-assembled everything. There are so many nuts and screws.

Success. No more nasty rattle. [Note to self: “Nasty Rattle” is a candidate for a good band name.]

View attachment 4297211 View attachment 4297212

That's exactly what I was gonna suggest. Something that acts as a little vice located where the buzz is coming from. Nice job!

 

[Ringhammer]

UPDATE:

Glued the front to back cross-brace and drove two screws in each front and back. Made an improvement, but still buzzing. If I press real hard on the back above the control panel it helps a lot, but I can’t add another brace there because the speaker is in front.

It’s tolerable, and probably fine when playing with guitar and drums, but it will still bugs the heck out of me. Any other thoughts? Sell it at a discount to a metal player and buy new with warranty?

 

[Ringhammer]

Just got back from a jam with some friends and the buzz is really a non-issue in a live playing environment. Just won’t use it for recording.

Also had another idea, since the buzz seems to dissipate when I push around the handle(s) and control plate, maybe I can glue and clamp some 3/4 x 1 strips behind where the handles and control plate screw down and use slightly longer screws to compress the plywood where it was cut for the handle and control plate. In case that is a source of the buzzing, where the holes were cut for the handles and control plate. I does look pretty rough at those cuts.

 

[Slaplord88]

@Ringhammer - you ever fully fix this? Mine is doing the same thing even after screwing down the cross-brace.

 

[Ringhammer]

I think I also glued some wood strips of 1 x 1/2” behind the locations where the handles screw in, and before clamping them in place, also glued where the ply was cut for the handle holes to maybe seal up any delamination where the cuts were. The strips behind the the handle screws is an attempt to squeeze the plywood at the cuts for the handles. I’m not sure if it helped but the handle are screwed in really tight. That also seemed to help. I also made two tiny marks in the tolex on the sides in case I need to screw in the cross race that goes side to side, but I have not needed to do that yet. This cabinet doesn’t get much use at the moment so I don’t know if it still buzzes, but the last time I used it it sounded ok as I recall. Definitely nothing I could hear while playing with a full band.