Mesa Boogie DC-3B with ghost notes while EQ is engaged

[adamsapple520]

Folks, I recently picked up a late 90's Mesa DC-3 combo and I noticed when engage the graphic EQ I get ghost tones like a 5th below the notes when I play the 7th fret thru like the 13th fret on the G string. So when I play an E thru say A I get these weird subharmonic tones happening. I get the odd tones on both channels and only when the EQ is turned on. It's not the speaker (happens on different speakers). Could it be bad filter caps feeding the negative voltage to the EQ transistors???

[nosaj]

Folks, I recently picked up a late 90's Mesa DC-3 combo and I noticed when engage the graphic EQ I get ghost tones like a 5th below the notes when I play the 7th fret thru like the 13th fret on the G string. So when I play an E thru say A I get these weird subharmonic tones happening. I get the odd tones on both channels and only when the EQ is turned on. It's not the speaker (happens on different speakers). Could it be bad filter caps feeding the negative voltage to the EQ transistors???

Looks like you have caps on the eq that could be leaking. See if you can figure out which eq slide affects it.
Here is a DC-3 schematic hopefully close enough
https://schematicheaven.net/boogieam...aliber_dc3.pdf\

nosaj

[adamsapple520]

Thx for replying nosaj, all slider movement doesn't really affect the ghost notes. The ghost notes are more prominent in the clean channel, maybe because there is more fundamental tone to modulate. Your schematic is for the older DC-3 version. Mine is the later DC-3b circuit of which I cant find the schematic for. I called Mesa and they said the only have one schematic which is BS cause I found just the power supply page of the DC-3b on another thread.

[nosaj]

Thx for replying nosaj, all slider movement doesn't really affect the ghost notes. The ghost notes are more prominent in the clean channel, maybe because there is more fundamental tone to modulate. Your schematic is for the older DC-3 version. Mine is the later DC-3b circuit of which I cant find the schematic for. I called Mesa and they said the only have one schematic which is BS cause I found just the power supply page of the DC-3b on another thread.

I included it anyways because it should be close enough to compare what you have to it. In my experience Ghost notes are issues with filter caps, but in this case I say compare your circuit to the EQ in the PDF I posted If they are same components do some voltage checks in that section. My wild ass guess might be the 10uf 63v cap in the EQ section since none of the sliders affect the sound.

nosaj

[adamsapple520]

Thx nosaj, will check voltage on filter caps associated with the EQ section. I'm gonna assume the zeners and the EQ transistors are ok and wouldn't cause any ghosting issues??