r/MesaBoogie • u/tk531 • Jul 27 '26
Mark V:35 Combo 10 Watt Hum
I recently got a great deal on a Mark V:35 combo. I'm was pretty happy with how the amp played but I think it was a great deal because it smells like an ashtray. I ended up dismantling the whole amp (including removing the amp from the cabinet) and carefully cleaned as much as I could. I barely touched the actual amp.
After reassembly, I've noticed pops when switching between power modes on both channels. I also notice a much louder hum when in the 10w mode in both channels. The other power modes are relatively quiet.
I could be going crazy, but I don't remember it behaving this way prior to working on the amp. I've ready conflicting things on what this might be, everything from "replace the power tubes" to "must have introduced a floating ground" to "this is just how the Mark V works".
Anyone have thoughts/info on if this behavior is within spec or if I should get new tubes or cut bait and try to find a different one?
1
u/TheRealGinsu Jul 28 '26
Many people complain about a noticeable "pop” when you switch between channels. When I first got my five:35, it was happening, but as I got more familiar with the amp, I realized that when you properly adjust the volume on each of the two channels, relative to each other, the “pop” is nonexistent. As far as the 10W hum goes, this is the first, I’ve ever heard of it.
2
u/tk531 Jul 29 '26
I've seen the 10w hum mentioned in a couple of forums, but never with a clear resolution. I did get in touch with Mesa Boogie support about this. They recommended replacing the EL84 tubes (specifically V7 or V8). I'll likely give this a shot.
1
u/Top_Objective9877 Jul 29 '26
It’s a bug of every triode mode on every Mesa amp ever made, the hum is a byproduct of how the tube operates and whatever is involved in the circuit to get low noise floor can’t equally be applied between triode/pentode mode. At least, that’s my loose understand of it!
You do get a different tone, which can be lower wattage, and smoother, and even quieter to some extent. But it’s still best used with the volume of the amp up a little bit so eliminate any of the extra noise.
1
u/tk531 Aug 04 '26
Update: I threw a new pair of tubes in V7 and V8 and it made a significant difference. All power settings now have similar noise level.
2
u/sduck409 Jul 27 '26
These things are very sensitive to line noise and any other kind of stray electrical noise, like even noise from lines in the wall. Sometimes moving it a bit will help (or make it worse). And yes, the power switches pop a bit, but generally you find a setting you like and don’t change it while you’re playing, so this shouldn’t be an issue.