crackle and hiss when not playing?

[FunkenGrooven]

Hey guys don't know if or where this might be addressed but after my series 2 rectoverb warms up about 5 minutes you can here a sort of crackling semi hissing noise. You don't here it when your playing but it ain't supposed to be there. The tubes are original but the amp really dose'nt have that many hours on it at all. I tried tapping on the tubes to get a reaction but did'nt seem to do anything I allso have a Fender Twin that does have old preamp tubes in it and it does the same thing. Any ideas? Thanks. 8)

 

[jbird]

Pre-amp tubes! :idea:

 

[tele_jas]

I'd bet it's a preamp tube. It doesn't matter how old they are, they can go our at any time. I've bought bad preamp tubes..... and on the other end of the spectrum I have a 1970 Deluxe that still has some original preamp tubes in it.

 

[t0aj15]

I had the same problem with my Mk IV until I bought a Furman Power Factor Pro power conditioner and a Furman AR-1215 voltage regulator, since then dead quiet. All the noise was coming through the AC line.

 

[parsky1]

When you touch the strings does it go away? Are there light dimmers in the room? If there is either turn those lights off or get a good power conditioner like a Furman.

 

[FunkenGrooven]

No it's not the lights the preamp tubes were it. Thanks guys. I needed some in a hurry so I ended up getting what this little hole in the wall music store had just as they were closing (Sovtek 12AX7WA) Not exactly what was in it but they seem to work at least. I doubt they are very good tubes I don't know much about them I allso picked up a set of EH EL34EH so I could try them out in the rectoverb about 10 min into it I smelled something cooking and looked in the back and the tube on the left was glowing hot bright orange I quickly shut it off and removed them went back the 6L6's and yes I had switched the bias to EL34 any ideas on that? I allso have a Nomad 45 that uses EL84's I'm getting the same problem from time to time one tube just starts to bake. Heeelllppp!!! 8)

 

[boogieslide]

Hmmmm, well new tubes sometimes smell for a bit. Not sure what is really burning off or why it is, but I have experienced it before and nothing was wrong with the tubes.
Hard to say if the glow you are seeing is really a bad thing without seeing it. Some glow more than others and orange is a normal color for the filament. If a tube is really going it will normally take out a fuse and not damage the amp. I actually just had a JJ 6L6 go on me the other day in my 5150. I turned on the power and I heard a weird noise and a pop and then throwing the stby on yielded no sound and no stby led. I took the amp apart, replaced the fuse, powered on again.....but this time cuz the chassis was out I saw it happen. On power up the tube produced a white light like I never thought a tube could do. Swapped it out and all is good.

 

[FunkenGrooven]

Yea I know what you mean about the smell but this was not the normal glow the plates were completly hot from top to bottom and only on one tube. It looked like a piece of metal that has had a blow torch running on it for awhile this is the power tube I'm talking about. The preamp tubes looked ok so I don't know. I appreciate any help though.

 

[fatboy135]

I also second tube preamp trouble

 

[Guitarzan]

Yea I know what you mean about the smell but this was not the normal glow the plates were completly hot from top to bottom and only on one tube. It looked like a piece of metal that has had a blow torch running on it for awhile this is the power tube I'm talking about. The preamp tubes looked ok so I don't know. I appreciate any help though.

So what tubes did you settle on?

 

[stokes]

If the plate on one power tube is glowing red as you describe,you have a problem.Redplating is not caused by a preamp tube.It is a problem with the power tube bias.Changing preamp tubes will not make it go away.Get the amp looked at before you have bigger problems.That tube looks like "a piece of metal that had a blow torch running on it for a while"because it is biased way too hot for some reason.It will without a doubt burn out.It will take the fuse out but it might take out more than that when it fries.Get it looked at asap.

 

[diamondschwin]

your amp like all mesa amps has a fixed bias, you need to buy tubes that fall within the range of what the fixed biase allows, you said you bought some EH el34 tubes, power tubes are NOT interchangeable like pre amp tubes, the tubes you bought are not in the correct range. when you just buy random tubes the amp would have to be biased for them by a tech, since mesa boogie has a fixed bias, as long you KNOW FOR SURE the tube you are buying falls into that range you can just drop them in yourself, replace the tubes with the original mesa boogie tubes you had in there, and talk to a reputable tech about getting tubes in the right range if you want a different brand.

 

[jamme61]

Once you put the orginal Mesa tubes back in there, keep an eye on the spot where the tube redplated. Even with the old mesa tubes in there. If it redplates again you know its not the tube. I had the same problem, and it was caused by me changing a lot of tubes, which broke the solder joint on the pins and caused redplating. Just keep an eye on it, to make sure.

 

[FunkenGrooven]

Hey thanks for the help guys the original tubes (6L6) I put back in and it works fine. In case it got missed my post I replaced the 6L6's with EL34's and I did slide the bias switch to the EL34 setting but it still redplated I'm playing on a series 2 rectoverb and this is the first time I have pulled the tubes out so maybe I need to find the right range EL's. The amp is less than a year old so if there are any suggestions on what tubes to use I'm all ears 8)

 

[diamondschwin]

Hey thanks for the help guys the original tubes (6L6) I put back in and it works fine. In case it got missed my post I replaced the 6L6's with EL34's and I did slide the bias switch to the EL34 setting but it still redplated I'm playing on a series 2 rectoverb and this is the first time I have pulled the tubes out so maybe I need to find the right range EL's. The amp is less than a year old so if there are any suggestions on what tubes to use I'm all ears 8)

if you want to try other brands, groove tubes number 4 through 7 are safe for use in mesa boogie, and they are rebranded JJ, Sed, etc. as well as their own american made tubes.. so email them and go that route