Sub-harmonic Distorted note: Blown Speaker or Tube?

[jazzgear]

I am getting a weird distorted sub-harmonic tone every time I play a note on the 6th fret of my guitar (actually it only happens 6th fret, A string). At first I thought it was maybe the setup on my guitar buzzing (which it did need one), but after a full setup the distorted overtone is still there....both clean or overdriven.

So I tried about 7 different guitars and the same result. So, I currently don't have another cab, or combo to try ruling out the speaker. So before I start swapping tubes I thought I post the issue here to see if anyone has had this happen.

It weird tone only rings out on the 6th fret.

Posting this in this forum cause I ruled out the guitar as the culprit so it has to be the amp.

Amp: Mesa Boogie Mark IV 1x12 Bubinga (Narrow Panel Combo) w/Celestion C90 speaker.

Setup:

Guitar -->Fullltone FB (original) --> G-System Input (4 Cabl4 Method)

I tried direct into the amp and the weird note is still there, so it's not anything in the signal path.

 

[Ventura]

Wasn't this just posted with some other cat having a D note issue??? Scumback piped in and mentioned a few issues that could lead to such "cone cry"...

Interesting...

V.

 

[titanamps]

how old is the MKIV? it could have some ghost notes caused by aging filter caps...

 

[jazzgear]

how old is the MKIV? it could have some ghost notes caused by aging filter caps...

It's not that old....it's near new....6 mos before the release of the Mark V...built in 2008

 

[jazzgear]

Wasn't this just posted with some other cat having a D note issue??? Scumback piped in and mentioned a few issues that could lead to such "cone cry"...

Interesting...

V.

It's there even at low volume. Just barely pluck the A string on the 6th fret...and you can hear the rumbling (distorted) sub-harmonics...so it can't be con cry

 

[glpg80]

Wasn't this just posted with some other cat having a D note issue??? Scumback piped in and mentioned a few issues that could lead to such "cone cry"...

Interesting...

V.

It's there even at low volume. Just barely pluck the A string on the 6th fret...and you can hear the rumbling (distorted) sub-harmonics...so it can't be con cry

any chance you can play another amplifier through the cabinet and isolate the problem to the amplifier?

if it is your amplifier and not the cabinet (which imho i believe it is, but it is better to not assume) then i have a few ideas, one already mentioned though.

are you the original owner? or did you buy used?

have you checked to make sure all tubes are secured properly into their sockets and are not moving/rattling?

could also be a loose solder point in the signal chain somewhere on the board. when was the last time you moved the amplifier? did it develop this problem after you moved it or did it suddenly appear? or has it been gradually getting worse?

you could just have a filter capacitor that could be defective/high ESR causing high ripple current. just because the amplifier is 3 years old does not guarantee the part's internal shelf life is of the same year.