Dual Rec Roadster Channell 3/4 died Suddenly :(

So my saga with this amp continues. The other night I was strumming along low volume with the amp that had not moved since I brought it home and mid chord my channel 3 died went totally mute, no weird noises or anything. I switched over to channel 4, and also nothing. However, channel 1 and 2 are still fine, generally sounding normal. I went to the local dealer and they sold me tubes for V2 and V3 replacement and a rectifier tube, but I looked and it was on Diode mode, so I'm not sure that makes sense.

Any help or insight is appreciated. Just for reference I rarely play and always at low volumes. Thanks

If only the 2 channels are affected, the rectifier doesn't matter. V3 would be the one to replace if it is indeed a failed preamp tube. 1 and 2 don't use it. Otherwise, the channels share everything else.

Let me know if the change makes a difference. If it does, perhaps you might choose not to return to that dealer. They just made an extra $30 in that case. No matter what, the rectifier tube was an add on and a shady thing to do.

Yup you nailed it here thank you so much, I returned the recto tube today. I replaced both 3 and 4 just because and problem fixed instantly. The last thing I wanted to do was bring the amp in like they suggested, pull and plug tubes was way easier. Finally playing again!

No problem. I like to help.

Another Cathode follower sudden death story.

I would have changed V3(CF tone stack) and V5(CF FX send) on the Roadster as those are the tube positions that have the cathode follower circuits. V4 is the reverb on the Roadster or RoadKing. If and when I have tone issues or sounds off I change both V3 and V5. If all channels went dead, check V5 if you are using the FXloop for master/solo control. If you get a Rectifier fault, you will know it as it usually blows the fuse and probably will not work until you remove the tube rectifier as it usually fails as a short which will be running parallel to the silicon diodes.

Afu, I have been reading up on your posts. Thank you for the information in detail. Brings me back to my days in audio amplifier design. I have been away from that for too long as I spend more time with digital control systems and software development. I think when I retire I will get back into amplifier design.

bandit2013 said:

Afu, I have been reading up on your posts. Thank you for the information in detail. Brings me back to my days in audio amplifier design. I have been away from that for too long as I spend more time with digital control systems and software development. I think when I retire I will get back into amplifier design.

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Hey, no problem. Before I became disabled, I was building/repairing guitars, building demo amps, and making pedals. I'd forgotten a lot of stuff from school, so I bought several books and read as much information as I could as I got started on the electronics. I contrasted several amps and investigated the developments from the '70s to the '00s, and realized some inaccurate info about the Dual Rectifier.

The people in the DIY pedal community, the AX84 community, and many others inspired me to make anything I found freely available. Since the Recto is a classic amp and is now built differently, I figured the information wouldn't harm Mesa, would be good for students, hobbyists, and tinkerers, and could also be used to make decisions on how to use it. Also, people who want to build a modern amp could use some of the information to make decisions about their own design, not to copy Mesa, but to innovate over the top of it, or to incorporate an idea, even if it is implemented in a different way. I see electronic design as a creative endeavor on par with music or art and ideas should be shared when possible to keep innovation rolling.

(Aside) Steven Johnson has a book and 6 part PBS documentary called "How We Got To Now". It covers how innovation works and how it made modern living possible. I would recommend either one to anyone who creates anything whatsoever. The concepts are illuminating and the stories provide context to illustrate how pieces come together from several sources to make progressive changes, which sometimes completely change our lives within a few steps of change (air conditioning and refrigeration, artificial light, clear glass, etc.). Even "failures" are productive.