Does this sound like a bad tube issue?

[stepvan]

So the long and short is I have a Marshall DSL 5CR that I got around the holidays as a gift from my wife, I have not put alot of time on it like 2 hrs a week but the other day I noticed that it would drop out very low volume on the full power setting and the .5 watt setting seems a weak and dropped sound a bit after a few minutes as well. Sound will usually come back on its own either by shutting off and turning back on or will simply just cut back in. Also the classic gain channel has no break-up whatsoever where it had a classic 70's kind thing going on prior to this. So could this be a bad preamp tube or a loose tube ?

 

[Milspec]

Sure could.

A bad power tube often results in a sudden loss of volume, but it can waver back and forth for awhile before finally failing all the way.

Bad preamp tube can cause a very noticeable loss of gain.

Get yourself another set of tubes and swap them out....likely nothing more than a bad tube or 2.

 

[stepvan]

Sure could.

A bad power tube often results in a sudden loss of volume, but it can waver back and forth for awhile before finally failing all the way.

Bad preamp tube can cause a very noticeable loss of gain.

Get yourself another set of tubes and swap them out....likely nothing more than a bad tube or 2.

Thanks, that is kinda what I was wondering. I have a bunch of 12ax7's so I can at least start there, I will need a ecc99 which also lists as a 12bh7 which I ordered off of fleebay so hopefully that will take care of it

 

[Dacious]

I'm not sure if the DSL5 shares the preamp design with the bigger DSL amps but if it does one of the preamp tubes probably the second next to the power tube will have a cathode follower triode. The bigger amps have three tubes with the third tube being the phase inverter.

That causes voltage/current to flow from the cathode to the grid and if a tube is a bit flaky can certainly cause that tube to display overheating and subsequent power loss that seems to come and go. You need a tough tube in that position- JJ or the Chinese metal E tubes that come branded Marshall or a vintage US tube. It doesn't affect tone.

 

[stepvan]

I'm not sure if the DSL5 shares the preamp design with the bigger DSL amps but if it does one of the preamp tubes probably the second next to the power tube will have a cathode follower triode. The bigger amps have three tubes with the third tube being the phase inverter.

That causes voltage/current to flow from the cathode to the grid and if a tube is a bit flaky can certainly cause that tube to display overheating and subsequent power loss that seems to come and go. You need a tough tube in that position- JJ or the Chinese metal E tubes that come branded Marshall or a vintage US tube. It doesn't affect tone.

I actually have some old stock electro-harmonics 12ax7"s from the early 90's that I am going to try later once I get out of work thanks for the info this small amp has two preamp tubes instead of three in the larger dsl's