#1
Hey guys - I have a Mesa Rectoverb 50 watt combo amp that lately seems to go in and out at random times.. I also hear added reverb sometimes or changes to the selected sound. At times it almost sounds like a kill switch is being applied over and over again.. then other times there's no issue. I have used a few different cables and this still intermittantly occurs. Any ideas ? Could use some help... didn't want to be at the mercy of a costly Mesa repair if I don't have to. Thanks in advance !
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#2
It's most likely tubes.

If it's cutting out I'd put money on the power tubes, but you can get a single preamp tube and put it in each position one at a time to check them first.
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#3
Yea I'd put money on a power tube, but could easily be a preamp tube. You can change the tubes yourself in most Mesas.
#4
another +1 for power amp tubes.

another +1 for buying a preamp tube.

i would re-tube the whole thing and have backups in case you need them. worst case scenario you have backups for tubes. extra tubes is never a bad thing. i like JJ's in my tremoverb. also, i really like a 5751 in V1 and the PI.
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#5
I just wanted to add that if you've never messed with tubes before, specifically power tubes, then make sure you do you research before touching ANYTHING. THERE ARE LARGE VOLTAGES AND CURRENT INSIDE A GUITAR AMP THAT CAN KILL YOU. You can pull the pre-amp tubes without worry.

Someone else here can correct me if I'm wrong, but I don't think that mesa is auto-bias, so you will most likely need to bias the power tubes if you replace them. Like I said above, be careful if you open the amp up. Don't be afraid of the amp tho. If you do your research you can safely change and re-bias power tube pretty simply. I recommend picking up a bias-probe if your amp doesn't have easily accessible bias pts.
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Last edited by red.guitar at Sep 29, 2015,
#6
Mesa recommends you use their rebranded tubes which are of the correct bias so that the amp doesn't have to be touched - just pop in the new power tubes.

Several companies, including Eurotubes, will sell you non-Mesa rebranded tubes that meet the Mesa specs.
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#7
I appreciate everyone's help !! So I guess I will get it retubed. I was hoping you were going to say a tube was possibly loose or something. I've never changed a tubes out so I guess I'll get an amp guy to do this for me. Hopefully I'm not looking at a fortune for this. Thanks again to everyone for helping.
GUITARS:
PRS Custom 24 (Black Slate 10 top w/birds)
ESP E-II Horizon NT-III (RDB)
ESP Eclipse II - Snow White

AMPS:
Mesa Rectoverb combo
#8
Quote by AXEFAN88
I appreciate everyone's help !! So I guess I will get it retubed. I was hoping you were going to say a tube was possibly loose or something. I've never changed a tubes out so I guess I'll get an amp guy to do this for me. Hopefully I'm not looking at a fortune for this. Thanks again to everyone for helping.

You can do it yourself. You don't need to bias Mesas if you use their tubes. Just switch them out.
#9
Hey man, before you pay a tech to look at, and switch your tubes for you. Try researching vids yourself. I just had to change all my tubes on my triple rec, I'd never changed tubes before, but I bought all new power, pre amp, and rectifier tubes from Mesa. About $200 total. There was a very helpful video on Mesa's website how to retube my amp the triple rec. I used to be overwhelmed by tube amps when I first entered their world, I paid basement techs 100s of dollars to retube, or diagnose my amps issues. But the nice thing about Mesa is that they're very user friendly. Now I didn't necessarily have to replace all my tubes at once, however, I bought the head second hand, and I'm just OCD that I wanted to completely re tube it. So in my experience just paying someone to look at your amp and maybe change a tube is about $50-$75. So for a little bit more, and about an hour of your time. You can change your tubes yourself. If you amp is anything similar to my triple rectifier. I don't have first hand experience with yours.
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#10
From your description, I'm thinking that a preamp tube is going/gone. The increase in reverb could be the few times it's actually working. That is V3 and V4. I'd guess that the problem is V3 because it affects more than just the reverb. V3A is just a gain stage and V3b is reverb recovery.
That's where I'd start anyway. Buy a JJ ECC83S and give it a go.


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Last edited by Cathbard at Sep 30, 2015,
#11
Also try unplugging the reverb cables from the amp chassis and see if the problem persists.

It may not be tubes at all. If it is, the amp does not need to be biased and you don't need to buy Mesa branded tubes. If you get power tubes - just get a matched set. Try the reverb cables and follow what Cathbard is suggesting.

I have a Rectoverb 50 head but don't remember which stage/side preamp drives reverb. I don't think I ever found out. My amp has a reverb problem that sounds similar to your problem and I just disconnected the reverb tank and then ended up taking it out altogether.

Good luck,
#12
yeah - as others have mentioned - if you do your research and knoe you can buy the same brand / spec of tube, it probably wnot need to be rebiased. plug and play. only for power tubes, preamp is not needed.

this is a great opportunity to experiment with preamp tubes. i have 2-3 kinds on hand for giggles. i think most guitarists do. buy some. cheap. do as others said, take an hour or two and with a FRESH preamp tube try swapping it in different spots. if that doesnt help, its probably the power tubes.

how old is the amp? if you have used it for more than 2 years of medium to heavy use, just retube it man. its part of owning a tube amp. bite that bullet. if you have never done it, you probably need to.

a good amp like a mesa isnt so much of an issue but 50% of amp sold come stock with crap tubes. crap quality and crap because they were shipped with those tubes in them. asa general practice i retube my amps when i buy em (power tubes, and then i always throw a 5751 in v1 preamp and perhaps a 12at7 in teh PI preamp position because of personal preference).
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