Tube amp weirdness

tommy p

tommy p

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I needed a Marshall head for a tribute band I'm in on very short notice and got an Artist 3203 for a pretty good deal.  I used it at a few gigs and I was able to get a good enough tone out of it for what I needed.  Trouble came at an outdoor gig when after playing for about 1h15m pushing the amp pretty hard, the high end seemed to cut out. intermittently.  Then it definitely started losing power and then coming back but even when the power came back it wasn't sounding "right", like the gain was gone.  It made it to the end of that gig, thankfully.

A few weeks later I tested it at home since the next gig was going to be a longer show.  After playing for about an hour at home, at much lower than stage volume, it died completely.  No sound at all.  I just turned it off and didn't touch it for another few weeks.  I have just tried testing it again and it came right on and sounds fine.  I played for a good 30 minutes at "too loud for home" volume, then left it on standby for over an hour and tested some more.  No issues.

Does anybody have an idea of what might be happening?  Should I swap out tubes?  Just looking for any home troubleshooting ideas before it goes in the shop.

 
When things like that happen, I usually think something thermal. Could be a cold solder joint that as things heat up then loses contact. Could be a component that is nearing the end of service life that is fine until it gets heated up.

Did it blow any fuses? When it "died" were the tubes still glowing?

 
I agree with Tbone - I would start by reheating all of the solder joints on the tube sockets and power resistors.

 
Swapping tubes is a simple troubleshooting method and an easy fix if that is the problem. More likely to be power tubes. You could also reseat the tubes while paying attention if the are loose.

Any way to know how old/used the tubes are?

Thermal issues can indicate filter caps going bad, too.

 
tbonesullivan said:
When things like that happen, I usually think something thermal. Could be a cold solder joint that as things heat up then loses contact. Could be a component that is nearing the end of service life that is fine until it gets heated up.

Did it blow any fuses? When it "died" were the tubes still glowing?
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No blown fuses, but I didn't notice if the tubes were still glowing.  I'll look for that if it happens again.

BoogieMKIIA said:
Swapping tubes is a simple troubleshooting method and an easy fix if that is the problem. More likely to be power tubes. You could also reseat the tubes while paying attention if the are loose.

Any way to know how old/used the tubes are?

Thermal issues can indicate filter caps going bad, too.
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I have no idea how old the tubes are so I thought swapping them out would be a pretty good idea anyway too.  I did reseat the power tubes and they were good and tight.

Biz Prof said:
IIRC, it's a SS preamp, tube PI, and EL34 power section.  I always thought they were cool as shit.
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Yeah, that's the configuration.  I use it for playing Malcolm in an AC/DC tribute band.  I wanted something nice and light since I always take a 4x12 cabinet, and sometimes two.  Also, I figured with it being only 30 watts I'd have to crank it pretty hard on the clean channel which is really key in getting a good AC/DC sound IMO.  It does the job well enough, but I've also thought about replacing it with an Origin 50 but the reviews on those are wildly up and down.

 
Tommy, not sure how you're set up for spare EL34s, but Pete Thorn's recent shootout left me with the same impression that he and Dave Friedman had;  The EH branded EL34 sounded "right"...and it's priced right, as well.  Friedman even commented how reliable the current production EH EL34s are.  I should probably get a pair for my Marshall, but the tech who serviced it last year noted that the early-90s-vintage Teslas that I put it that amp in '93 still tested strong and sounded glorious. 

 
Biz Prof said:
Tommy, not sure how you're set up for spare EL34s, but Pete Thorn's recent shootout left me with the same impression that he and Dave Friedman had;  The EH branded EL34 sounded "right"...and it's priced right, as well.  Friedman even commented how reliable the current production EH EL34s are.  I should probably get a pair for my Marshall, but the tech who serviced it last year noted that the early-90s-vintage Teslas that I put it that amp in '93 still tested strong and sounded glorious. 
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It should be noted that the EH EL34 tubes are the ones that Mesa Rebrands as their EL34 STR 447. They are quite ruggedly built, and sound good. I have had good luck with them in my amplifiers.

 
We used to use solid state Marshalls for the jam session and they developed a fault exactly like described when pushed hard for extended periods, especially if you were using pedals to push the front end very hard. From what I recall it was a known fault with the preamp stage that we got sorted by a local tech. 

 
tommy p said:
I have no idea how old the tubes are so I thought swapping them out would be a pretty good idea anyway too.
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Definitely!  I remember a salesman at a music store once told me that a HUGE fraction of tube amp owners never change the tubes, and then once they get issues associated with worn out tubes, they just sell the amp!

 
HamerCustomEr said:
Definitely!  I remember a salesman at a music store once told me that a HUGE fraction of tube amp owners never change the tubes, and then once they get issues associated with worn out tubes, they just sell the amp!
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Sounds like a LOT of stupid people.

 
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HamerCustomEr said:
Definitely!  I remember a salesman at a music store once told me that a HUGE fraction of tube amp owners never change the tubes, and then once they get issues associated with worn out tubes, they just sell the amp!
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My favorite person to buy from! Clean it up, fresh tubes and whatever else it needs and sell it! Make a couple hundred bucks for my time. Not getting rich but I enjoy it!

 
HamerCustomEr said:
Definitely!  I remember a salesman at a music store once told me that a HUGE fraction of tube amp owners never change the tubes, and then once they get issues associated with worn out tubes, they just sell the amp!
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I recall watching an interview with Carol Kaye where either she or one of her colleagues laughed about her not knowing anything about replacement bass strings because by the time her instrument's strings were needing to be changed, she just went to a local store and bought a new one.  

 
Biz Prof said:
I recall watching an interview with Carol Kaye where either she or one of her colleagues laughed about her not knowing anything about replacement bass strings because by the time her instrument's strings were needing to be changed, she just went to a local store and bought a new one.  
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I remember reading something about the early days of the Who, and how John Entwistle would break strings, which was bad because stores really didn't really sell sets of electric bass strings at the time. Could be my brain making things up though.

 
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