question about a sound im getting from my hartke 3500

[AndyW83]

when i have the tube pre amp cranked up i get a quite noticeable staticy almost crackling sound.. its not a consistant sound and it comes and goes.. however it does it quite often..is this normal? is the tube pre amp going bad? how can i get rid of this? help!

[BurningSkies]

Could be a tube going bad. Or it could be dirty contacts on the tube socket. Try this: open it up & remove & reinsert the tube a few times. See if that helps. Of course a new 12AX7 is cheap, so trying a new one wouldn't break the bank either. It could also be one of your cords or the effects loop.

[AndyW83]

i dont think its my chord because it only does it when the tube pre amp is cranked up... how much are the tubes?

[AndyW83]

blah cord

[BurningSkies]

A single 12AX7 will run you between 10-20 bucks unless you want vintage or fancy.

[AndyW83]

im going to try whatu said and remove the tubes.. ive never done this.. they screw in or just pop out? how do i get to them

[monkeyking]

Sounds like the tube to me. Mine started getting hissy, then crackly.

If I remember correctly, replacement was pretty easy on the HA3500. Take the cover off. There is a metal ring that secures the tube in place. It is removed or loosened with one screw. Pull the old tube out, put the new tube in, being careful not to bend the pins.

My Hartke is over ten years old, so I don't know if the guts have changed much. Hope that helps.

[BurningSkies]

That's the way mine is too (also an older mosfet 3500). Once you get the lid off the amp, the tube has a retainer 'halo' lift up and turn to the side and you can remove the tube. It comes out by pulling it straight up. Don't twist or turn it just straight up. Slide it in and out of the socket a couple times to see if you can get it to make better contact.

If that doesn't do the trick, spring for a new tube.

[JimmyM]

ya, just pull up on it and it comes out. new one pops in there, too. nothing difficult.