Amp sounds weak after complete tube swap, help!

Talk about tubes and their effect on your tone

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Mark I
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Amp sounds weak after complete tube swap, help!

Post by tzoranski » Mon Jul 24, 2017 5:13 pm

So I have Roadster that I blew a 6L6 in about two weeks ago. While I was waiting to get some new tubes I pulled the 4 6L6's from my much newer Roadking II. The Roadster sounded so good with the newer tubes I decided to swap the 6 12AX7's as well. I follow the tube charts in the manuals but when I powered up my Roadster things sounded really bad. Channel 1 sounded fine but when I switched to channel 4 it had no gain. It sounded like an overdrive pedal. Then when I switched it back to channel 1 there was barely any volume at all. So I decided to swap back the original 6 12AX7's but there was no change. I double checked to make sure the tubes were seated properly. I really don't understand what I could have done. Any thoughts how to correct this would be greatly appreciated.

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Re: Amp sounds weak after complete tube swap, help!

Post by TStone2 » Fri Sep 15, 2017 10:45 am

sorry, I don't have an answer and I hope your problem is fixed. I just find it surprising that with 130 views of your post and not one response. I have a tube question in the Modern Amp area, 50 views and not one response. :roll:
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Re: Amp sounds weak after complete tube swap, help!

Post by woodbutcher65 » Sun Jun 17, 2018 2:36 pm

You might want to take your amp to a good technician and have him check it out.

Although it's kind of unlikely, the bad power tube may have damaged the output transformer. If that's the case then the transformer will have to be replaced.

It's more likely that the screen resistor burned up. But they're supposed to do that to save the tube from drawing excessive power and killing the transformer.

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Re: Amp sounds weak after complete tube swap, help!

Post by Markedman » Fri Aug 17, 2018 4:19 pm

JP2C, Mark llC++ DG, Mark IV-A/B.

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