DSL-40C popping noise

[Outa_Tune]

When I fire up my DSL-40C, for about 2-3 minutes it sounds awesome, but then it makes a pop and the volume goes significantly down where I have to reach over and adjust it back up.

I'm thinking a tube is going out, It has the original Marshall tubes. I tried tapping them to see if any were microphonic, and I didn't see any of them doing this. I'm wondering if I should check the bias voltage, do a tube walk, or just change them all out. I have no idea how old the tubes are and how much they have been used, I bought the amp used and had it for about 2 years. It doesn't get played loud, it's my home practice amp.

If I do a tube walk and find a bad tube, I'm gonna change them all anyway. But it would suck to change the tubes and have it still pop. I don't have another tube amp at the moment to swap tubes.

Thoughts?

[Simon_F]

Re: DSL-40C popping noise

The first thing I would check for is a dying pre-amp tube. Get yourself a new 12AX7 and try it in each pre-amp position in turn, to see if the issue goes away. That's potentially the cheapest solution.

In my experience dying pre-amp tubes make popping / hissing noises on the way out, while power tubes just stop working.

Or, since you've had the amp a couple of years and don't know how much use those tubes have had, just buy the full replacement set. I've always had good results with JJ's in Marshalls.

[Gtrjunior]

Re: DSL-40C popping noise

I have also noticed that my Marshall pops when power tubes are fading as well.
But yes, rolling a preamp through the positions is the cheapest way to diagnose.

[Outa_Tune]

Re: DSL-40C popping noise

I ordered a complete JJ retube kit with the EL34ii's. Will let you know if that fixes it.

[Outa_Tune]

Re: DSL-40C popping noise

Woo Hoo, got a new set of JJ tubes and she's back to normal again.

[Simon_F]

Re: DSL-40C popping noise

Glad you got it fixed