#1
Hey all, while playing on my amp (a valve combo marshall jcm 2000) it suddenly made this REALLY loud, unsettling bang noise which i've never heard it make before - half way through playing (clean channel). It was loud enough to almost have made me **** myself haha, so I was wondering if there is a reason to be concerned? I just had it serviced about a week ago, all the power valves and key components on the chipboard were replaced and needless to say it sounded flawless after that (it still does) the guy I took it to has been repairing valve amps for over 30 years and is a great guy so I trust there's nothing dodgy.

So yeah should I be concerned about the bang? it definatley sounds like something blew inside it, and I don't know if i'm exagerrating or not but it sounds like a bit of the tone is 'missing' since the bang (again I might just be exaggerating).

any advice would be great, thanks!
#2
Maybe you blew a tube? Maybe a tube was breaking in? Sounds kinda scary since I have the same amp. What year was yours made? I heard JCM2000s made before 2004 have a lot of problems.
#3
Ahh, well when I bought it last year in november the guy told me he's had it for atleast 8-9 years, and it had never been serviced. So definatley before 2004 lol. The guy that repaired my amp told me the same thing (the older ones having quite a few problems). Would be a shame if one of the valves blew already, I haven't had time to play it that much since I've had it repaired and I don't even have it that loud when I practice.

Wondering if I should perhaps take it back to him just to check? problem is he's an hours drive away and I really don't fancy it again especially as there could be nothing wrong with the amp
#4
is one of the tubes running hotter than the other it's paired with?

EDIT: not sure which combo you've got. if it has two tubes, it's obvious they're the pair I'm talking about. if it has four, the two in the middle are a pair, the two on the outside are a pair.
Last edited by GrisKy at Sep 21, 2009,
#5
Loud bangs from an amp are generally bad providing you didn't bump into it when it happened.
I wondered why the frisbee was getting bigger, then it hit me.
#6
How do I tell if one valve is running hotter then the other? from what I can see they all glow equally as bright as the other (no idea if that helps). To be more specific on the model of amp - it's a Marshall JCM 2000 DSL 401 combo (40 watts). It still sounds fine but again something feels different, I would ignore it otherwise but the bang didn't sound atall good.
#7
Quote by Moonfishlol
How do I tell if one valve is running hotter then the other? from what I can see they all glow equally as bright as the other (no idea if that helps). To be more specific on the model of amp - it's a Marshall JCM 2000 DSL 401 combo (40 watts). It still sounds fine but again something feels different, I would ignore it otherwise but the bang didn't sound atall good.

If you had it serviced a week ago the tech should be willing to take a look at it for free, since this may have been his mistake. I would definitely want to have it checked, at his expense.

Edit: I've always been scared of big amps for this reason. Once the Windsor I used to own let out a full blast (100 watt) screech because one of my pedals AC adapters pulled out. It was so loud I felt like I had been punched in the chest, and I'm sure all my neighbors heard it too. Scary.
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Last edited by tubetime86 at Sep 21, 2009,
#8
Quote by tubetime86
If you had it serviced a week ago the tech should be willing to take a look at it for free, since this may have been his mistake. I would definitely want to have it checked, at his expense.


this.

also, yes, you can tell by the glow in most cases.
you're still getting sound, but it's not quite right, and the 40w is the single 12" combo, right?

could be a faulty speaker connection, signal's still going through, but it's weak.
fuse should be good, or you'd hear nothing (or horrible loud squeels 100% of the time)... and the tubes look fine... hmmm...

take a soft cloth and make sure all the tubes are fully inserted, and take a look at your preamp tubes. something tells me they could be at fault.
Last edited by GrisKy at Sep 21, 2009,
#9
Take it to the guy that serviced it. If he did service it only a week before, you would have thought he would have spotted anything wrong.
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