Mystery Cab Synth-ey Artifact in decay

[Number179]

Starting to drive me nuts with this 810e (I forget what year, but its the plywood version outside of the "dark years").

Check out the audio which is an iphone recording. Synth-ey sounding buzz, or fuzz probably more accurately when the held note decays. It goes away when the string vibration is muted; and isn't really audible when played with normal attack. It is definitely artificial and annoying.

Background: the fuzz follows the cabinet only. Persists with different heads connected to it. Fuzz is not present with same heads connected to other cabs (Aggie DB412, for example).

Thoughts / experience / diagnosis techniques requested. Thanks!

 

[Mike Caldwell]

Sounds like you ruled out the amp and the bass as the noise is not there with other cabs and amps.

Does it do it at really low volume, does it get worse at loud volumes?
Get one of the tone generator apps and use that for the test signal input or a keyboard.
At a lower volume try to listen to each speaker and see if you can narrow it down.
Could be something loose in or on the cabinet.

 

[Thumpin6string]

Sounds electronic to me, not like a failing speaker or loose cab parts. Does the cab have a crossover? If so, it could be something to do with that. Just spit balling here. Hope you figure it out.

 

[Wasnex]

Try to narrow it down to one specific driver. Move the phone close to and directly in front of each driver.

Does you cab include the cab splitting jack panel? If yes, one of the 1/4" inputs has a switching contact. When you plug into this jack, it splits the cabinet into two 410s. Perhaps the switching contact is dirty or loose, which could cause the signal to arc across the contact.

I believe the top jack does the switching:

Plug into the top jack and only the top four 10s should work. All of the other four jacks connect to the bottom four 10s.

You should be able to bypass the switching contact: Plug the amp into one of the bottom four jacks. Run a speaker cable from one of the bottom four jacks to the top jack. If this clears the buzz, then the upper jack is the most likely source of the problem.

I don't recommend hot swapping the jumper while the amp is on and connected to the cab.

 

[Number179]

Thanks, team! Heading home to investigate further. Got some good leads here, so thank you. Stay tuned