Dear All,
I recently bought a Mesa Boogie Stiletto Ace. It has been fine up to now but has started making some crackling noises when I hit certain notes. It isn't constant but does seem dependent on resonant frequencies. It has a set of Mesa tubes, well at least the front ones being the rectifier and power amp valves so I'm guessing that there's a decent chance that they are the orignal ones. Before I lash out on a new set of tubes can I please pick your brains as to the cause of the noise and the likelihood of it being valve-related? So far I have done the following:
-Swapped guitar;
-Swapped cable;
-Plugged in the the return jack on the effects loop to cut out the pre-amp and played through that;
-Checked and swapped the speaker - I was going to do this anyway so it made sense to do so whilst I had the back off;
-Tapped the front valves with a pencil with the amp on which generated some crackling similar to what I'm getting whilst playing.
None of this made a difference to the crackling.
Is this suggestive of a power amp valve about to let go or possibly something requiring a trip to a technician? I'd be grateful for any thoughts please. Also, there doesn't appear to be a lot of room to remove and insert valves, do I need to take the chassis out to do this and am I likely to encounter any high voltages by doing so?
Thank you!
"I've got the moobs like Jabba".
Comments
If you bypass the valve rectifier (set the switches to Diode) you can eliminate that as the cause.
If it's not the rectifier, its probably a power valve. It's possible that tapping either will make the other one crackle since the vibration can be passed via the chassis, so it's best to lightly hold the other one with a cloth while you tap one.
If you identify it as one valve, replace both with a matched pair and keep the good one as a spare. You don't need to open the chassis to change valves on a Mesa - the bias isn't adjustable. It's easiest to use Mesa-branded valves since they are tested to be in the middle of the bias range. They do them in several 'colours' - if you want the exact same sound and to make best use of the spare (if you ever need it) get the same 'colour'.
The existing valves aren't necessarily the originals since this may have already been done.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Mesa really have sewn up the 'exorbitant premium plus prices for branded consumable items that they don't actually make' market, FFS
:-O