#1
okay i have a marshall jcm 2000 tsl 100. i was playing it today and all of a sudden the amp got really quiet and started humming, i went over and looked at the head and the tubes were glowing bright red and i touched the amp and burned my hand. not to mention lately it has been taking a long time to warm up. im gonna go with instinct and say i need new tubes because ive had the amp over a year and they are way passed due but i have never had to change tubes before so i wouldnt know for sure. are tubes th problem? if so what kin should i get toreplace them, i met a guy who had the same head and had mesa el34 power tubes and i liked the sound but i think i need pre amp too any suggestions?
Quote by jmac72187
The vox can do it. It just can't do like BlackGrindDeathBloodMurderDevilKillYourUnbornChild Metal.
#2
I can't really help much, but there is another thread on here called 'Everything you ever wanted to know about TUBES!' if you search 'tube amp replacement' it was the tenth from the bottom a sec ago. There is a lot of helpful info there about different tubes and how they sound.
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#3
The tubes are supposed to glow, but not like the bulbs on a Christmas tree. You said the amp was so hot that when you touched it, it burned your hand. I take it you didn't touch the tubes (they are supposed to burn your hand, so don't touch them!). If you touched the metal face plate or the knobs and they were searing hot, it is probably a bias problem. Have the bias checked before you do anything else to it.
#4
they were like christmas lights lol brighter then i have ever seen them, and i touched the top of the amp because there is a plastic vent over the top of them and usually its just warm but it was actually really hot this time. and over the last few months ive been having to turn it up louder and louder to reach a good practice volume.
Quote by jmac72187
The vox can do it. It just can't do like BlackGrindDeathBloodMurderDevilKillYourUnbornChild Metal.
#5
sounds like its probably the power tubes. you should replace them and see if it fixes the problem. tubes are like tires for a car. they should last a while but theyre supposed to wear out and blow out eventually. as far as buying tubes dont worry too much. different production runs or brands or however you want to look at it have subtle differences but theyre mostly like lightbulbs. as long as you put in the same tube type ( as in el34 or 6L6 not brand to brand) they will work almost exactly the same. im pretty sure the amp you named is a 100 watt so it will take 4 el34s. dont just buy any four, get a matched quartet so all the tubes are matched. you will have to check the bias after the replacements are in to make sure youre getting good sound and not burning up your tubes. youre going to want ax7s in all the preamp spots but you can make the amp respond more gentley with power tube distortion by switching the phase inverter to 12at7 or 12ay7. like i said all the differences in tubes are very exagerated by many people but you should still get a respectable brand because the quality control is better.
#6
theres a place in my area thats supposed to do a good job of diagnosing amps and replacing tubes and doing it right. do you think its worth going there and spending the money to have them do it? or shgould i do it myself
Quote by jmac72187
The vox can do it. It just can't do like BlackGrindDeathBloodMurderDevilKillYourUnbornChild Metal.
#7
Quote by FatalGear41
The tubes are supposed to glow, but not like the bulbs on a Christmas tree. You said the amp was so hot that when you touched it, it burned your hand. I take it you didn't touch the tubes (they are supposed to burn your hand, so don't touch them!). If you touched the metal face plate or the knobs and they were searing hot, it is probably a bias problem. Have the bias checked before you do anything else to it.

tube bias doesnt get set wrong by itself. if it was working properly for a while and suddenly went haywire its probably the tubes like i said. however the bias is easy to check so it wouldnt be a bad idea to take a look at before you do anything else just to make sure its set correctly. and since im typing again ill add that you can easily switch out the phase inverter preamp tube without having to set it up or anything so for 12 bucks or so you could get the 12ax7 that came factory with the amp AND the 12at7 and try them both out. its like a pedal that can totally change the character of your amp. the good thing about that is you can have both at your disposal for a very small amount of money but the bad thing is it can be a pain in the ass to change them out to swich between the two.
#8
Quote by talldude175
theres a place in my area thats supposed to do a good job of diagnosing amps and replacing tubes and doing it right. do you think its worth going there and spending the money to have them do it? or shgould i do it myself

if you can work a screwdriver and not accidentally break delicate glass things you could swap the tubes yourelf and just pay the shop to check/set the bias and save yourself some money if you dont have a voltmeter/experience to do it yourself. just make sure you DO NOT use it after the new tubes are in but it hasnt been biased yet. personally, i think that amp of yours is sweet enough and expensive enough to be a little extra sure it stays in great condition even if it has to cost you a bit more. dont do anything youre not sure about and risk fcking up something as awesome as a 100 watt marshall.
#9
Quote by MichaelOfCanton
as far as buying tubes dont worry too much. different production runs or brands or however you want to look at it have subtle differences but theyre mostly like lightbulbs. as long as you put in the same tube type ( as in el34 or 6L6 not brand to brand) they will work almost exactly the same.

This is not true; you should always bias your tubes, otherwise your tubes may sound sterile or red plate.

Quote by MichaelOfCantonim
pretty sure the amp you named is a 100 watt so it will take 4 el34s. dont just buy any four, get a matched quartet so all the tubes are matched.

Yes, do get a matched quartet.

Quote by MichaelOfCanton
you will have to check the bias after the replacements are in to make sure youre getting good sound and not burning up your tubes.

Yes. If you diy, make sure you know how hot to bias your tubes.

Quote by MichaelOfCanton
youre going to want ax7s in all the preamp spots but you can make the amp respond more gentley with power tube distortion by switching the phase inverter to 12at7 or 12ay7.

Matter of personal preference, there should be lots of information regarding what tubes to use in each slot depending on what you want.

Quote by MichaelOfCantonlike
i said all the differences in tubes are very exagerated by many people but you should still get a respectable brand because the quality control is better.

Many 'respectable' brands (I'm looking at you, Groove Tubes), are just rebranded Slavic tubes.

Quote by MichaelOfCanton
sounds like its probably the power tubes. you should replace them and see if it fixes the problem. tubes are like tires for a car. they should last a while but theyre supposed to wear out and blow out eventually.

The image of a tire executive holding a meeting to decide when tires should blow out gave me a hilarious mental image.

Quote by talldude175
theres a place in my area thats supposed to do a good job of diagnosing amps and replacing tubes and doing it right. do you think its worth going there and spending the money to have them do it? or shgould i do it myself

It's more then possible to do it yourself, but if you're uncomfortable with maintenance you can take it to an amp tech. It's more economically feasible to diy it, however.

Oh and you probably shouldn't turn on your amp if your tubes are shot or you could potentially blow your fuse(s) and output transformer.
#10
thanks for the advice guys, i think im gonna have my friend come over and look and it and give me a second opinion because he has the similar jvm head and has replaced his tubes before by himself and his amp works well so he must know what hes doing haha
Quote by jmac72187
The vox can do it. It just can't do like BlackGrindDeathBloodMurderDevilKillYourUnbornChild Metal.
#11
Quote by talldude175
thanks for the advice guys, i think im gonna have my friend come over and look and it and give me a second opinion because he has the similar jvm head and has replaced his tubes before by himself and his amp works well so he must know what hes doing haha

Remember, if your amp has redplated (your tubes lit up like a light bulb or a Christmas tree instead of how tubes normally light up), do not turn on your amp. You can blow your fuse (realistically not a big deal) or your output transformer (much bigger deal).
#12
okay sure thing
Quote by jmac72187
The vox can do it. It just can't do like BlackGrindDeathBloodMurderDevilKillYourUnbornChild Metal.