Roadster volume drop and then swell when changing channels.

[LesCarl]

Heya

I have a roadster head that sounds like a charm.. And all is well until it gets hot. After about 30-60 minutes when i change channels the volume drops to zero and there is a delay of 4-6 seconds before the volume of the amp is at normal levels. At first when i switch channel there is nothing, and then it comes swelling up to normal level after 4-6 seconds.

The tubes were mesa EL34s, i just changed back to 6L6s to see if the problem persists.

This is not that reverb delay issue, this is not that small small delay when switching either, this is a real long delay which makes the amp useless in live situations.. and i mean, cmon.. thats what its for right?

This only occurs when the amp is hot, and when it gets to cool down it gets back to normal again and switching is fine.

I have so far inly used it with a 16 ohm cab, in the 16 ohm jack. Someone suggested to use the 8 ohm jack to lighten the load, think that could help?

I will be at home again Monday and trying it with my own 8 ohm cab.. It will be interesting to see if there is a difference.

Anyhow.. anyone experienced this? Or at least have a good idea what it might be?

Thanks in advance

/Carl

 

[disassembled]

Are you using a voltage converter? Is your power source good? You should measure the voltage going to the amp to make sure it isn't dropping.

Maybe the muting circuit is getting too hot and staying active for longer than it should(the mute circuit activates when you switch channels but is only supposed to be used for a split second to reduce any pops).

I don't think the 16 ohm output has anything to do with your problem.


Greg

 

[LesCarl]

Heya Greg and thanks for your answer!

No voltage converter, my power source is good (i hope) :wink:

Could be the muting circuit yeah.. lets hope its not



Anyone got another differential diagnosis ?

 

[clutch71]

Volume swell is usually symptematic of a bad power tube going on you. Read the tube section of your manual and it should speak to this. I've had new Mesa tubes fail. The good news is they have a 6 month warranty. Not sure how hard they are to come buy in Stockholm, but it is just a suggestion. Swap the tubes and see if it persists.