Hi,

Recently got a POD HD500 and a DT50 212. I'm noticing that at high volumes (especially on clean tones), I hear a slight crackling/ pinging sound coming from inside the amp. these sounds seem to flare up when I hit a lowish note on my guitar at moderate volumes (almost sounds like a snare drum is rattling nearby when you hit a loud lowish note, but I don't have a snare drum around). Tapping on the preamp tubes with a pencil, I noticed that the preamp tube on the right of me (I am looking at the back of the amp. The caged power tubes are in front of me and the preamp tubes are behind.) pings when I tap it, the tube on the left makes no sound whatsoever.

I was thinking I might have a bad preamp tube so I want to replace both of them. I read on this site that LP tubes should not be used in V3 position. Which preamp tube is the V3 position?

Also what preamp tubes would you suggest to get to replace the ones in the amp?

I do have a bit of a white noise problem (constant irregardless of amp volume) especially with topology III/pentode/ClassA - Would changing the preamp tubes improve the noise issue as well?

Thanks for your help.

RG