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What's wrong with my amp?


I've got an HRDx with the Omega mod, and a Cannabis Rex speaker. Lately, My amp has been breaking up a lot easier than it used to. At high volumes, I feel like I can feel it breaking. This amp has been absolutely wonderful since I got it back. I was wondering if this is the tubes, or something bigger that I need to worry about?


Could be the power tubes. Put your spare pair of power tubes in, and bias that sucker. See if that helps out. Other than that, you may have to take it to a tech.



Senior Member
Maybe I'm wrong here, but I think if you pick up a set of the same brand tubes as you currently have in the amp, you could just drop them in and take a listen - yes, you should have a tech bias them for optimum long-term performance, but I don't think it's 100% necessary for short-term testing.


Gold Supporting Member
indravayu, you're sort of 1/2 right. Most average tubes will drop into most average amps without blowing anything up. Unfortunately that's not ALWAYS true so here's how to stay out of trouble:
1. Replace the power tubes with a new set, as similar to the ones you have as you can find.
2. Turn on the amp standby and let it warm up, then switch to play. Watch the black stuff inside the tubes. There should be a little glowing spot at the end, but the main parts should stay black. There may be a blue florescent glow in the tube. If the black stuff starts to turn red or orange, turn off the amp and take it to a tech NOW because you'll hurt it and your tubes if you go any farther.
3. If there's no nasty red glow, play the amp and watch the tubes. IF they still look OK, how do they sound? If they sound good, you should be OK till you can get to a tech and get them biased. If they sound nasty and harsh, they're biased too cold and a tech is your only solution.

OR, even better, just get a tech to replace the tubes and bias the amp up.

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