Mark III: reverb decreases headroom

[Heady Jam Fan]

Anyone else notice that turning up the reverb decrease the amps headroom?

I only noticed it recently, but I guess it makes sense. Certainly a Fender Princeton has more headroom than the Princeton Reverb...

Anyway, I was on the clean channel with some reverb. I clicked on my wah and got some overdrive. I know this happens sometime, but my amp was set pretty clean and the best way to cleanup my amp: turn down the reverb! Hmmm, I thought that was interesting. Wanted to hear other people's experiences - anyone notice this or can recreate this?

Just to make sure it wasn't a hardware anomaly, I tried a fresh reverb tube, different RCA cables and it is also a new MOD reverb pan (the old accutronics was sounding bland - the springs seemed to be sagging, which I changed out a while back).

 

[UglyNoize]

I've never had my III up loud enough to notice a loss of headroom, but what I did notice is that the reverb scoops mids. It's enough for me to not use the built in reverb.

Good to know I'm not the only one with strange reverb experiences with this amp :lol:

 

[Heady Jam Fan]

I've never had my III up loud enough to notice a loss of headroom, but what I did notice is that the reverb scoops mids. It's enough for me to not use the built in reverb.

Good to know I'm not the only one with strange reverb experiences with this amp :lol:

Hmm, hadn't listened for a tonal change. I think there are two issues with my amp's reverb.
- The effect send/return jacks may have been corroded, which can cause distortion when using the loop. Replacing the jacks or cleaning the contacts can fix this.
- However, I still think I lose a bit of headroom even after cleaning the fx loop jacks. I know many amps run their reverb too hard, but about a year ago my reverb tube was clearly beat and lacking tonal definition. I replaced it, along with a few other tubes there had lost a bit of liveliness, but nothing as noticeable as the reverb tube. Yesterday, I was recording, so my reverb was turned completely down, and the amp lost volume. I replaced the reverb tube and my volume came back. I think something is off with my reverb circuit's bias, but the amp tech said the reverb circuit was working fine...

I'd hate to run my signal through another pedal, but I might toss a small reverb in the FX loop and call it a day. For now. When I actually have some money, I'll send my amp out to Mesa Boogie for a real checkup.

 

[Markedman]

Strange things happen with Mesa amps, all other amps too, I suppose. I had a Mark lll with the reverb tank removed and when I turned the reverb knob up, it added extra gain. When I contacted Mesa they said, "that is strange." My old C+, volume 1 went up as I turned the lead master up. When I contacted Mesa they said, "hmmm, that's is strange." Things can be strange with amps.

 

[Heady Jam Fan]

Strange things happen with Mesa amps, all other amps too, I suppose. I had a Mark lll with the reverb tank removed and when I turned the reverb knob up, it added extra gain. When I contacted Mesa they said, "that is strange." My old C+, volume 1 went up as I turned the lead master up. When I contacted Mesa they said, "hmmm, that's is strange." Things can be strange with amps.

Hmm - that first example, the gain increasing with the reverb knob, is sort of what my amp seems to be doing. It's possible this 12AX7 reverb tube just has a short life, or it is just normal for the Mark III (like a lot of Fenders) to run the reverb tube hot (ie., it may not be an issue with bias). I don't think its too uncommon for reverb to affect gain/headroom: compare a non-reverb Princeton to a Princeton reverb. Big difference in headroom.

I'm trying to recall if you can pull the reverb tube in the Mark III (of course I can test this). I might have to toy with the idea of switching to a reverb pedal.

 

[BlackBoxy]

tube problem

 

[Heady Jam Fan]

tube problem

I mentioned in the OP, I tried multiple tubes. After exploration, I think its either normal - a lot of amps run their reverb tube hard and lose headroom when reverb compared to without reverb - or the reverb tube is run a bit too hot. I tested out a solid-state tube replacement, which seems to work, just in case it is running the tube too hot. I also started using a reverb pedal in the effect loop, which reduces noise and increases headroom. I'm using a Neunaber Wet reverb which also has a bit of pre-delay built in, so I think that adds some clarity overall.