No reverb

[Azrehan]

After having my MarkV for three whole days now (2 of which I was at work) I have discovered that I have no reverb functionality whatsoever!

At first I thought the reverb was really subtle and that I just couldn't hear it, but there is zero reverb. Both plugs are plugged into the reverb unit, so that's not the problem.

I have noticed a few curious happenings in the back of the head, but am not sure if they are causing it. This is my first tube amp! Shame

Firstly, one of my 6L6 tubes is not pushed in as far as the others. There is about a 3 millimeter gap in which the plugs are visible. It is still glowing fine
so I don't think this is the culprit.

Secondly, the 5U4G tube is only glowing from the bottom (non plug end) of the tube. The 6L6's glow at both ends. If someone can tell
me what the hell this tube does that would help.

Thirdly, the amp crackles when I switch it off. Even if I have it on standby for 5 or 10 minutes. I think this may mean one the preamp tubes which drive the reverb is faulty. Maybe this crackle is normal though. I have no idea.

Anybody know wtf is going on here? This amp has gone from California to South Australia so I hope it's something simple. :lol:

 

[Supreeth]

After having my MarkV for three whole days now (2 of which I was at work) I have discovered that I have no reverb functionality whatsoever!

At first I thought the reverb was really subtle and that I just couldn't hear it, but there is zero reverb. Both plugs are plugged into the reverb unit, so that's not the problem.

What are your reverb knobs set to? I noticed on mine that the reverb had very little effect till I pushed the knob past the 12:00 mark. It could well be that one of your preamp tubes is faulty as well.

Firstly, one of my 6L6 tubes is not pushed in as far as the others. There is about a 3 millimeter gap in which the plugs are visible. It is still glowing fine
so I don't think this is the culprit.

I would definitely make sure that the tube is seated properly. You should pull out the tube gently and then reseat it. Since your amp journeyed all the way from Petaluma to Adelaide (?)(That's southern australia right?), I would try to make sure that all the tubes are seatled right including the preamp tubes. Improperly seated tubes might well be causing your issue with the clean channel sounding "dirty" as well but I'm no expert.

Secondly, the 5U4G tube is only glowing from the bottom (non plug end) of the tube. The 6L6's glow at both ends. If someone can tell
me what the hell this tube does that would help.

The 5U4G is the rectifier tube and it is normal that it does not glow as brightly as the 6L6 tubes. This is not an issue IMO.

Thirdly, the amp crackles when I switch it off. Even if I have it on standby for 5 or 10 minutes. I think this may mean one the preamp tubes which drive the reverb is faulty. Maybe this crackle is normal though. I have no idea.

How does this crackle sound like? Is it like an electrical spark sounding or is it like a long click? If it is the latter then it is just the relays turning off and is normal. If you hear loud pops, hisses, or that electric spark kind of sound I would have it looked at by a Mesa authorised service center. Since this is your first tube amp it may not be a bad idea to have the amp looked at by an authorized service center anyway, and your amp is under warranty too so you can ask for a new set of tubes as well

 

[Azrehan]

After having my MarkV for three whole days now (2 of which I was at work) I have discovered that I have no reverb functionality whatsoever!

At first I thought the reverb was really subtle and that I just couldn't hear it, but there is zero reverb. Both plugs are plugged into the reverb unit, so that's not the problem.

What are your reverb knobs set to? I noticed on mine that the reverb had very little effect till I pushed the knob past the 12:00 mark. It could well be that one of your preamp tubes is faulty as well.

Firstly, one of my 6L6 tubes is not pushed in as far as the others. There is about a 3 millimeter gap in which the plugs are visible. It is still glowing fine
so I don't think this is the culprit.

I would definitely make sure that the tube is seated properly. You should pull out the tube gently and then reseat it. Since your amp journeyed all the way from Petaluma to Adelaide (?)(That's southern australia right?), I would try to make sure that all the tubes are seatled right including the preamp tubes. Improperly seated tubes might well be causing your issue with the clean channel sounding "dirty" as well but I'm no expert.

Secondly, the 5U4G tube is only glowing from the bottom (non plug end) of the tube. The 6L6's glow at both ends. If someone can tell
me what the hell this tube does that would help.

The 5U4G is the rectifier tube and it is normal that it does not glow as brightly as the 6L6 tubes. This is not an issue IMO.

Thirdly, the amp crackles when I switch it off. Even if I have it on standby for 5 or 10 minutes. I think this may mean one the preamp tubes which drive the reverb is faulty. Maybe this crackle is normal though. I have no idea.

How does this crackle sound like? Is it like an electrical spark sounding or is it like a long click? If it is the latter then it is just the relays turning off and is normal. If you hear loud pops, hisses, or that electric spark kind of sound I would have it looked at by a Mesa authorised service center. Since this is your first tube amp it may not be a bad idea to have the amp looked at by an authorized service center anyway, and your amp is under warranty too so you can ask for a new set of tubes as well

Thanks man.

I have tried the reverb at all settings 9:00 to 4:00. There is nothing there. The switching off sound is like crackling bacon on a fry pan but quieter. That's the best I can describe it. I will take it to the guys at the shop I bought it from and ask (tell politely) them to fix it tomorrow. The tube which isn't seated is a worry.

"Improperly seated tubes might well be causing your issue with the clean channel sounding "dirty" as well but I'm no expert."
- Good spotting 99!

 

[Azrehan]

I just pushed the 6L6 back in nice and tight and still no go on the verb.

*********!

 

[Azrehan]

Another question... Albeit probably stupidly ignorant... :lol:

Is it safe to run the amp with the preamp tube spring-loaded metal covers removed so that I can see which one is faulty (or isn't glowing) or will this
cause a catastrophe?

"I has a tubes valve?" :lol:

 

[Supreeth]

Another question... Albeit probably stupidly ignorant... :lol:

Is it safe to run the amp with the preamp tube spring-loaded metal covers removed so that I can see which one is faulty (or isn't glowing) or will this
cause a catastrophe?

"I has a tubes valve?" :lol:

I have done this before with no issues on my Roadster head when I had it with no issue. I've never done this on the Mark V but it shouldn't be an issue as long as you're careful when moving the amp around etc. I don't know for sure which preamp tube is responsible for the reverb (I would think v5) but you can swap out each tube individually till you can hear the reverb kick in.

The other day I had some pedals in the FX loop and was wondering why I couldn't hear them. Then I realized that I had not turned on the FX switch on the footswitch and felt like an idiot for about 5 minutes, but I'm sure you checked that the reverb switch is activated on the footswitch right?

 

[Nermel]

Usually a faulty tube will glow just like the rest of them...look in the back of the manual on the diagram that states which tubes are for reverb and which are for gain stages...I think the MK Vs reverb driving is shared by two tubes, so you might have to replace two tubes....my suggestion is to swap tubes with the reverb tubes and if that doesn't work swap one preamp tube at a time....and if that doesn't work...Well call Mesa

You might want to call Mesa first...it's up to you

AH and even better...take it back to your dealer...the can do it and you won't to pay for labor or tubes

 

[Azrehan]

Yeah. I checked the foot switch.

I will take it to the shop I bought it from tomorrow. They can deal with it. I just hope it doesn't need to go back to
california! I have a gig in 3 weeks.

 

[Don]

My Express needed a new Accutronics reverb tank. It was a simple warranty repair.