Damn! My amp just went *pop* and then X-(
a_gherkin
Posts: 77
Its a marshall jcm900 valve half stack. the valves are pretty old, i know but i think it is probably a blown fuse, what do you guys reckon?
I was jammin to 'breathe' and i heard a loudish pop and the power light went out. i unplugged it, plugged it back in and turned it on again. the red light came on for a split second and then went out again. any one got any ideas?
Damn first my car blows up and now my baby goes kaput.
Any help would be awesome, im having guitar withdrawal symptoms already!
Cheeers
Gherk
I was jammin to 'breathe' and i heard a loudish pop and the power light went out. i unplugged it, plugged it back in and turned it on again. the red light came on for a split second and then went out again. any one got any ideas?
Damn first my car blows up and now my baby goes kaput.
Any help would be awesome, im having guitar withdrawal symptoms already!
Cheeers
Gherk
Post edited by Unknown User on
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Comments
If you're saying valve and you're likely in England you can check out these guys.
http://www.watfordvalves.com/mainindex.htm
though you may also check out http://www.thetubestore.com they seem to like the svetlanas.
I'm a fan of both Electro Harmonix and EI which I currently have in my Orange.
Replace the fuse, if it blows again quickly, unplug it and take it strait to an amp tech because something internal is wrong.
your detective skills are top notch my friend
have been thinkin about buying some new valves for ages now. i think there is no time like the present. i just turned it on again a few mins ago and it worked fine, but i dont think i will use it any more until it gets looked at...
chances are it's simple. likely something internally has shaken loose like a ground, but it's weird it popped and the fuse didn't blow. It probably is a power tube issue since you've likely never changed them and they are getting old.
However, when you're dealing with rather large capacitors and high internal voltage, it's just much safer to spend the money and have it checked out. It could actually save you some money down the road on caps, tubes, sockets, transformers and the like not to mention save you from shock.
I'd take it in to an amp tech and let them fiddle with it a while. Marshall amps scare me anyways, but you've got some weird problems.
If your retubing and don't have the equipment to rebias your amp, then yeah have it done by someone.
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You are the second person in my life that has recommended Teslas. The first was a local amp service guy, he talked me into them. And I was honestly not impressed at all. With the tone, and with the durability. Of course with tubes are always tubes, they can last 10 seconds or 10 years, but I've seen the worse reliability come from that brand (not just my amp, I've know of two other people with the same gripes). I'm not saying your wrong, its just my own opinion.
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Okay, I'll bite:
If you are replacing tubes with the same tube (like replacing EL-34's with EL-34's), you shouldn't need to re-bias the amp. If you are changing tube type, you will DEFINITELY want to re-bias. It's not a bad idea to have your amp biased once in a while to make sure all the voltages are correct (especially if you're having problems). But, as a general rule of thumb, it's not necessary if you're just replacing old tubes with new ones.
Individual tubes vary in current draw (some more than others), even 4 EL84s of the same manufacture. A matched set of tubes are a set of tubes thats current draw is with in + or - 5% of each other. This is very small amount and when biased you are set. But these aren't necessarily going to be the same current draw as another matched set of EL84's from the same manufacturer. So the amp needs rebaising.
The overal tone (even if slightly) will still be affected by a set of tubes that aren't bias'd correctly. Places like the tube store have all there tubes grouped by the current draw so that you can still continue to by matched sets out of the same group. In this case you don't need to rebais.
Current draws that are slightly off only have minor problems, larger current draw differences can shorten the life of the tubes greatly.
Hey I'm not here trying to step on toes, I'm just here to learn, and to help out with what I've found out from my past experiences.
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hey maybe you're right. I've never had a bad experience with them but that's not to say they haven't made some shit. I think every tube company has made a few bad batches. Apparently the Svetlana's (SED's) are fucking brillant.
as of now I'm loving my EI's. It'd be nice to have some old Mullards but they get kind of expensive. I guess it's just the luck of the draw.
What are you using at the moment?
The only exception is the rectifier in the Vibro Champ, gotta go NOS Phillips, GE, or JAN.
Currently (Guitar amp wise) I have NOS RCA Power tubes (can't remember the freaking model #, and the amps sitting at the studio) (EL84's).
I have a silverface bassman 100 watt heat that I'm going to retube with those Electro-Harmonix tubes that are copied off an old RCA tube. Never heard them never tried, them, heard some good reviews though. I'm using that head strictly for my (Get this crazy idea) "Bass Rig". Hey SVT's cost 3 times as much used, and 4 times as much new!!! Plus I never understood why one needs 300 watts of tube power for a bass. So I'm giving it a shot.
Anyways as soon as its time to change the RCA's I'm not sure what I'm switching too honestly. There used to be this cool used guitar shop by my house, that had tons of NOS tubes, really descently priced. Well they went out of business a year or so ago, so I'm not sure what I'll get now. Something at the http://www.tubestore.com for sure though! And sense its a combo amp something that can handle the abuse!
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I've heard quite a few bands use a Fender Bassman head as a bass amp. The key is to run it through a decent cab, like a nice 4x10". One band I've worked with had a Bassman 50 head, and they borrowed my old Sunn 6x10" cab, that was one of the best bass sounds I've ever heard. The only thing is, they're better for a mellower sound... you won't get as much funky 'pop' out of a tube amp. They're also great for an overdriven bass sound...
As far as wattage on bass amps, lower frequencies take more energy to generate. That's why a concert sound system has really big amps for the subs, and smaller amps for each level above that. It doesn't take nearly as much energy to get really high frequencies. Also, having extra wattage means less sag in the power amp, and a more consistant signal.
I've played thru a bassman in the past (trial thing), also thru a SVT, and a 70's Peavey tube head (can't remember the dam'n name).
I love my 4x10 ampeg cabinet I has a great tight low in. I've played the head thru it already for a trial and it has great potential, not its going thru its overhaul.
I'm not one to play any slap bass or anything (never really cared for the "lead bass" theory either). So it will be a cool experience.
I understand why they make the high wattage bass stuff. I was just joking in a way. In my opinion yeah the SVT is the best sounding bass head I've ever heard, but in a small bar (which is the usual for me), its way way overkill. And there is nothing worse then too loud of stage volume. After all thats why they make P.A's.
But in all the bassman will be cool. Its not the "norm" around here for a bass player, I've always been one to play thru something different. plus it doesn't way 140lbs like the SVT. I have to get rolling on it checking sockets etc... prior to retubing.
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Nice Setup. Let us know how it goes. Those AVT's are just getting insane, and 300 watts worth of 5881's gets pricey in itself. I think the extra power just gets you more flexibilty and a solid clear bottom end, but yeah, you can get that from 100 watts depending on the venue you play I guess, and hell we have DI's now. I wonder how much the old Sunn bass amps are going for now.
In Britain and Austrailia Tubes are called Valves.
And I thought you were just joking...
Yeah, valve=tube.