What would you deem an amp "service"?

[Me]

I bought an amp second hand and was told it had been "serviced" 4 months ago. Turned out it was a bit dodgy, and the volume jumped quieter when it warmed up and giving it a good pat on the top made it come back. The power tubes looked pretty well used. I sorted it by retubing it and biasing it and it's been fine since.

I was curious what you folks would expect a "service" to mean? I'd presumed that would mean new tubes. To use a car analogy, just checking the bias to me would be the equivalent of checking the oil dipstick. To me that's not a service. Checking everything is still currently working, that's more like the annual MOT test our vehicles have to have in the UK - that's not a service. To me changing the oil + filter is a service and so replacing the parts/stuff that regularly wears out over time is a service i.e. for a tube amp that's the tubes every few years - that is a service.

I said I don't think they should list an amp as serviced unless it's been retubed. Seller thinks seeing that it works and checking the bias hasn't drifted very far out of spec is a service.

I'm not gonna make a fuss or name them as I'm not that kinda guy, but was curious if you bought a tube amp that had "been serviced" what would you expect that to mean? Am I expecting it to mean more than it does? Or would you expect that to mean a retube too?

 

[RaceU4her]

Caps and whatever other parts that can go bad being changed

 

[Me]

Caps and whatever other parts that can go bad being changed

TBH I've never replaced any caps in any of my amps. But other than the caps, would you expect that to mean tubes?

 

[Me]

This is a 13 year old Marshall btw. Do you think that should have caps changed yet? Not that I was expecting that to have been done.

 

[Mike Oxhuge]

I would expect a thorough once over of the amp including tensioning tube sockets, inspection for bad or leaking electrolitics, Deoxiting the pots and testing or replacing and rebiasing of the tubes. It should function and sound as new when completed.

 

[Me]

I deoxited all the pots/jacks myself as I wasn't convinced that'd been done. Caps looked ok when I was inside. Tapping them didn't show them to be microphonic or anything. Not sure how you otherwise test them, hence I'd have thought the EL34s would just be replaced if known to be old. But problem stopped when I retubed it.

 

[311boogieman]

I'm not an amp tech but replacing tubes just to replace tubes does not always make sense. Checking for bias drift, letting it run for awhile and playing through the amp at volume should all be reasonable things. The fact that your problem was only fixed by replacing the tubes shows something was missed. But new production tubes are not automatically going to fix all problems. Kind of depends on what was in there originally and what options are available for new. If possible, I would ask for the original tubes if they replaced the with new.

What if they were killer NOS tubes with plenty of life left?

 

[lester]

I've always thought of it as if you perceive there's some sort of problem and you take it to somebody to resolve. That's service

 

[Me]

I'm not an amp tech but replacing tubes just to replace tubes does not always make sense. Checking for bias drift, letting it run for awhile and playing through the amp at volume should all be reasonable things. The fact that your problem was only fixed by replacing the tubes shows something was missed. But new production tubes are not automatically going to fix all problems. Kind of depends on what was in there originally and what options are available for new. If possible, I would ask for the original tubes if they replaced the with new.

What if they were killer NOS tubes with plenty of life left?

They were Marshall tubes and the amp is only 13 years old so not NOS. I still have them because I retubed the whole of it myself. So TBH I don't know if it was pre or power tubes. Swapping them one by one and then having to let the amp warm up for ages, then still not being sure if you'll find which it is at short notice isn't gonna be very helpful when I want to actually use the thing, not take many weeks trying to work out if I may or may not have fixed it, only for it to ruin a band practice where I we're paying for a practice room by the hour.

So I retubed the lot at once. That seemed to fix it. The thing had been overtightened into the head shell and bent the chassis corners slightly so was a shit to get the bolts back in the case. So I just retubed the lot and played it for a number of evenings out the case. Then deoxited all the pots and jacks and bent the chassis corners straight too before I finally put it all back.

Seems the FX loop volume of the series/parallel loop doesn't go slightly quiet when the loop's on now either.

 

[skoora]

They were Marshall tubes and the amp is only 13 years old so not NOS. I still have them because I retubed the whole of it myself. So TBH I don't know if it was pre or power tubes. Swapping them one by one and then having to let the amp warm up for ages, then still not being sure if you'll find which it is at short notice isn't gonna be very helpful when I want to actually use the thing, not take many weeks trying to work out if I may or may not have fixed it, only for it to ruin a band practice where I we're paying for a practice room by the hour.

So I retubed the lot at once. That seemed to fix it. The thing had been overtightened into the head shell and bent the chassis corners slightly so was a shit to get the bolts back in the case. So I just retubed the lot and played it for a number of evenings out the case. Then deoxited all the pots and jacks and bent the chassis corners straight too before I finally put it all back.

Seems the FX loop volume of the series/parallel loop doesn't go slightly quiet when the loop's on now either.

Hold on to the tubes and when you’re next at a tech see if they’ll do you a solid and quickly run them through their tester. Might end up with several good spares and they actually find the problem one which you can toss.

 

[Me]

I've always thought of it as if you perceive there's some sort of problem and you take it to somebody to resolve. That's service

In my head I think of that as a "repair". Anyhow, this is kinda why I'm asking what other people to perceive a service to be. Back to the car analogy - I get it serviced once a year when noting is wrong but is scheduled preventative maintenance. I get it repaired only when it breaks. I don't generally change my power tubes very often. But if I was going on a tour and I knew they were a number of years old I'd do it as preventative maintenance. Anyway, I'll shut up as I'm supposed to be getting other peoples take on it, not pushing my own.

 

[DanTravis62]

If she cradles the sack, it's a "Service"

 

[MadAsAHatter]

Service would be going through everything checking for worn caps, bad solder joints, loose connections, bias drift, etc. Replace anything that needs replacing, reflow solder where needed, tighten nuts ans bolts, clean pots so they're not scratchy. I would include testing tubes in that but only replacing them if they're bad.

Was the amp shipped to you? Tubes can get internally damaged by being bounced around during shipping.

 

[technomancer]

"Serviced" means a tech went over it and did basic maintenance and fixed anything that was wrong. It doesn't automatically imply a retube unless the tubes were showing wear / having issues.

Tubes fail, it's entirely possible being banged around in shipping / transport caused a tube to fail that was fine when the amp was sold.

 

[Me]

Tubes were removed and bubble-wrapped individually during shipping. Problem only appeared after leaving it on from a number of hours at a higher volume which I didn't get to try properly til I'd had it nearly 2 weeks.

Maybe I'm being unreasonable then with what I deemed a service to be and just got unlucky. I just feel a bit bummed out as I could have bought any of a few off reverb or ebay, and got this older one as even though it was older, it was from an amp seller who said it had been serviced so figured I wouldn't have any problems or surprise bills and it meant I wouldn't have to take it apart and stick about £200 of tubes in it after only owning it a few weeks. I guess some of the ones I took out are probably reusable still though once I've worked out which are reliable still, and that's the nature of tube amps. They'd have probably taken it back if I'd asked, but shipping a 35 kg amp half way across the country when I figured I may well be able to fix it myself didn't make the most sense. Guess that's the story of my life though - I'm sure it would be easier if I had no clue, didn't know anything and just sent stuff back.

Seems a great amp though now I've fixed it. I wanted something smaller and lighter for practices where I felt lazy or small pub gigs where heads, cabs and all the other crap seemed a bit much. Had a Fender HRD to try do the same thing for a few years and just never liked it, no matter what pedals I tried in front. But this JVM410C just ticks all the boxes and the whole 100W 2x12 combo weighs less and is easier to carry than just my Diezel head in it's flight case alone which comes in at nearly 40 kgs.

Guess you live and learn and a service doesn't mean new tubes.

 

[technomancer]

Bottom line always have a spare set of tubes and plan to retube if an amp is being shipped. If you don't need to consider it a win and move along.

I've literally had tubes fail within a week in a brand new amp.

 

[cobrahead1030]

An itemized list of what the service included…

“Gave it a general clean up including the pots, pull switches, jacks, EQ sliders, preamp tube pins and sockets, and cleaned up some previous repair work where an orange drop cap had failed.
Also replaced all the electrolytic caps, numerous resistors as needed, performed the reverb glitch update, added screen resistors for the Class A power tube sockets and grid isolation resistors to the A/B sockets, cleaned the rotted foam out of the reverb tank and fixed all the connectors, jacks, and plugs, and added the steel shield cover plate.
Lastly, gave it a burn in and test with a bench set of power tubes, and swapped around the preamp tubes for best results.

The total cost is XXX including parts, labor, shipping, and tax”

 

[311boogieman]

^ so did you service it?

If so sounds like you gave it a good once over

They were Marshall tubes and the amp is only 13 years old so not NOS. I still have them because I retubed the whole of it myself.

I know.

Some of my response was just 'in general' what I would expect as it relates to tubes. I should have been more clear about that part.

 

[DanTravis62]

^ so did you service it?

I mean, if he cradled the balls i think by definition he did

 

[lester]

In my head I think of that as a "repair". Anyhow, this is kinda why I'm asking what other people to perceive a service to be. Back to the car analogy - I get it serviced once a year when noting is wrong but is scheduled preventative maintenance. I get it repaired only when it breaks. I don't generally change my power tubes very often. But if I was going on a tour and I knew they were a number of years old I'd do it as preventative maintenance. Anyway, I'll shut up as I'm supposed to be getting other peoples take on it, not pushing my own.

I generally don't like to waste money on stuff that's not needed and taking an amp in for them to give it a once over seems ridiculous, maybe that's just me.