saturn Posted September 17, 2016 Share Posted September 17, 2016 I know when you replace tubes, the amp is supposed to be biased. Will it hurt the amp or tubes to replace one tube (or all of them) for just one night without having the bias adjusted? I have a gig tonight, and one of my tubes in the Legacy is turning black on the inside. I have a new set of matched quads, but don't have time before the gig to have it set. I've been playing it as-is for several weeks, but can hear how it's not been sounding as good. Or I can just use my Roland Blues Cube for one night. Thanks in advance for the suggestions. Edit: think I'm going to just use the Blues Cube until I can have the Carvin serviced. Link to comment Share on other sites More sharing options...
Dub-T-123 Posted September 17, 2016 Share Posted September 17, 2016 For power tubes you should replace all of them with a matched set. Whether you need to bias the amp depends on the type of amp. With preamp tubes you can replace one and don't need to bias the amp Link to comment Share on other sites More sharing options...
deeman Posted September 17, 2016 Share Posted September 17, 2016 If they're a matched quad of the same make that you currently have in there, you should be okay. Frankly as long as you are sticking with the same type of power tube you should be 'okay.' As long as you're not switching from el34s to 6l6's or anything the amp should be fine for the show. Link to comment Share on other sites More sharing options...
kidblast Posted September 19, 2016 Share Posted September 19, 2016 Frankly as long as you are sticking with the same type of power tube you should be 'okay.' As long as you're not switching from el34s to 6l6's or anything the amp should be fine for the show. I'm speaking from my own experince (I have three tube amps) unless it's cathode biased class A not necessarily. It wont hurt to "try" and it will probably get you thru the show, but it may not sound optimum. two of my amps are not cathode biased, and one is.. that's the only one that doesn't need a re-biasing when the tubes are changed out. Link to comment Share on other sites More sharing options...
deeman Posted September 19, 2016 Share Posted September 19, 2016 Frankly as long as you are sticking with the same type of power tube you should be 'okay.' As long as you're not switching from el34s to 6l6's or anything the amp should be fine for the show. I'm speaking from my own experince (I have three tube amps) unless it's cathode biased class A not necessarily. It wont hurt to "try" and it will probably get you thru the show, but it may not sound optimum. Agreed, it would be 'okay' as in it wouldn't completely suck and the amp should be fine. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted September 19, 2016 Share Posted September 19, 2016 I must say that while you will almost certainly be fine I have, in the past, fitted valves in the power amp and found I can't get them anywhere near spec on biasing, needing to change a resistor value so saying it's fine isn't the whole story. There's a small chance it isn't fine. That's exactly why it's said that you should check. Had I just pushed valves in and left it they would have been a failure. Link to comment Share on other sites More sharing options...
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