#1
Hey guys, I recently picked up a DSL50 head and I think the tubes are due for a change. The amp sometimes makes a weird high pitched feedback sound I think could be a microphonic preamp tube. So it isn't much of a choice.

The tubes that are currently in the amplifier are EL34's. I could use a tad bit more gain and a little more bottom end but I am not sure what tubes are compatible with this amp.

Guess I'm looking for a slightly more modern sound. Suggestions?
#2
Try some KT77 tubes instead of the EL34's. if you want to stick with EL34, check out the EL34L tubes. Maybe even a set of 6CA7 tubes. For pre amp tubes, I'd jet several diff kinds so you can experiment.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#3
Stick with EL34s unless you've got a particular sound in mind. A bias may be all you need, if it's running cold that'll rally affect the sound.

As for the preamp tubes, it's not difficult to isolate the microphonic tube and then replace it, or possibly swap it into a less crucial socket like a reverb driver.
#4
I've never biased an amp before. Though I do have a multimeter and common sense. Any place I can take a quick course on how to bias an amp?

Also, this feedback is weird. Its sudden. Sounds first like sonar and then SQUEEEEK then it promptly goes away. Not like any bad preamp tube I've ever experienced.
#6
Quote by kyle62
Stick with EL34s unless you've got a particular sound in mind. A bias may be all you need, if it's running cold that'll rally affect the sound.

As for the preamp tubes, it's not difficult to isolate the microphonic tube and then replace it, or possibly swap it into a less crucial socket like a reverb driver.


The amp was running really hot even by Marshalls suggested standard of between 40-45mv. I read 50 mv and up on each tube plus there was a disparity of 5mv between the tubes. I set em around 41mv. Not sure how that is going to affect the sound.

Think I may pick up some new tubes soon. I'll buy a pair of EL34Ls and KT77's. Try both. Whatever I set I like less I will use as emergency back ups.
Last edited by Tyler.Allain at Dec 22, 2011,