Bad tubes?

[drummerguy1010]

A few weeks ago, my RM100 started making a slight scratching/popping/static sound. It does it on all 3 channels. I've switched guitars, cables, run guitar/cable/amp, made sure all 3 modules were seated properly and did not have corrosion on the connections (they looked like they were brand new.) I'm guessing its the power amp tubes? The amp has not been moved for over a year, is played intermittently and at bedroom levels. It still has the original tubes, so maybe its time for something new?

Edit: I also looked at the back and the LED's that are supposed to show a bad tube are not lit, and all the tubes are glowing brightly. So maybe its not a bad tube?

Any suggestions?

 

[drummerguy1010]

And additionally, if I do change them, I understand that I can put two different sets in, correct? For example, have the tubes set up like ( 1 2 2 1 ), correct?

 

[KillTone]

A lot of times a bad preamp tube will make sounds like that. Try changing the input tube (it is the one closes to the 1/4 input jack).

This is the postition where you want to use the best tube (low noise/good tone quality). Usually a 5751 or a 7025 there.

 

[drummerguy1010]

On the modules or on the power amp itself? I think I forgot to mention that it does this sound whether it's on play or standby, if there is a plug in the input jack or not, etc. I just ordered a quad of 6L6, and a quad of fast blow 1/4 amp fuses, so I'll put in some work when they get here...

 

[Julia]

V1 = the tube closest to the input jack of the amp. That one. You want something with very low microphonics in there.

However, preamp tubes should last years. With todays tubes I'd look at the power tubes. I have a Fender amp that was doing as you describe after the power tubes had been in there a couple years. On close inspection while I was playing I discovered one of the tubes was arcing periodically. So I replaced them and it's fine.

 

[KillTone]

What Julia said.

Input tube = V1 = the tube closest to the input jack on the amp.

That is a little strange that you can still hear the noise when the amp is on standby.

 

[walshinator666]

I wonder if this is the same problem i'm having.If I palm mute a E chord( the chord doesn't really matter)and let it fade out ,as it's tailing of a crappy sounding crackle noise ends the note.I believe the crackle sound is always there you just can't hear it until the note fades.

 

[Julia]

I didn't see the "hear it all the time whether or not the amp is on standby".

Perhaps the problem is in the switch. IMO the switches are not very good.

 

[drummerguy1010]

Well, the confirmation email that my tubes are on their way showed up today, so I'm hoping that it is an arcing tube. I also ordered more fuses just in case. Hopefully this does not go beyond a tube/fuse issue because I really don't want to spend my mod money on amp repairs.

 

[drummerguy1010]

Well, a change of tubes to Electro Haromix 6l6's biased at 34 seems to have fixed it, for now. Appreciate the replies.