Does my DSL401 needs tube replacement?

[kavoo]

I have a Marshall DSL401 combo. Bought it some month ago. Pior to that I had the Valvestate 8080. Generally I'm very satisfied with the amp change, old DSL was my target from the beginning (I play mostly Iron Maiden and AC/DC covers for pure home fun).

But there's one thing that concern me regarding the tone.

Generally I play at my apartment at low volume levels and I'm prepared for the fact that this amp won't sound as good as cranked up all the way. Nevertheless I'm under the impression that it's tone should be much better. My amp generally have a serious lack of trebles and gets a bit muddy at the bottom end. I'm pretty certain that it should have more punch and crisp sound even at the bedroom level, especially that I have replaced original Gold Back speaker with Vintage 30 (made in UK).

Furthermore - when I'm turning the amp on and start to play, the tone seems quite OK but after few minutes gets noticeably worse.

Does it mean that the tubes in my amp have worn out and needs to be replaced? I have googled to find some clues and found this site:
http://www.thedailyguitar.com/6-common- ... -replacing

It says:

These are the most common signs that tubes need replacement.
[...]
2) Loss of high end. Little or no treble.
3) A muddy bottom end. Sounds like there is too much bass and note clarity is lost.
[...]

Can you confirm it, guys?

[surfnorthwest]

Yes...you really don't know the history of the amp so to make sure your getting the best performance from it do this.

Replace all the preamp and power tubes.
Have the amp biased correctly.

That should make a noticable difference.

Be sure to buy good quality EL84 power tubes, I suspect those are the issue.

[kavoo]

Many thanks for an answer, mate.

What tubes are you recommend? I heard that for the preamp the Tung-Sol tubes are pretty good, but what about the power tubes? I cannot afford Mullard or Gold Lion. What do you think about JJ Electronic or Electro-Harmonix? Will they fit in DSL401? I heard that not every tube can be used in this amp.

[burnsy]

Agree with Surf. This amp eats EL84's. JJ's are probably the safest. Make sure you get the bias right, there are two different settings depending on when the amp was built. I put all the details on a previous post.
If you went to Marshall for replacement valves they would give you JJ's for the power valves and the same preamp valves as installed on the Vintage Modern, JJ for V1 and Shuguang for V2-4. I'd go with that as a good starting point.

[surfnorthwest]

If you can find them I would install RFT tubes. The will hold up better then modern production tubes and sound great.

http://www.thetubestore.com/Tubes/EL84- ... -EL84-6BQ5

[kavoo]

OK, I'll buy all JJ's. Thanks guys!

[surfnorthwest]