Possible Blown Tube ?? Not sure

sugaragus · 10-17-2009, 11:25 PM

Hello all. New to this forum but after looking through all the posts, there seems to be a lot of great information in here. My situation is this. I have an older JCM 800 combo, probably from the late 80's. Bought it a year ago and love the amp. I mainly just play in my basement with friends so the amp rarely gets moved. I went to plug in yesterday and noticed the 2 wires to 1 of the 2 speakers was disconnected. Possibly my cat was back there and pulled them out when he jumped out. I connected them back and when I play, the amp is missing all of that great Marshall sound. It's a very thin sound now and it sounds to me like a tube is blown. The 2 tubes I can see both light up and get hot. The other 2 have a blue casing and I can't tell. Can the problem have something to do with the wire connecters coming undone( I just put them right back on and doubt it) or can a tube be blown. How do i tell if one is blown so I know which one to replace.

Thanks so much for any information. When we played last night I had to use my fender...what a let down as I hate that sound. Help me get that 'marshall' sound back.

I know that's a long explanation...sorry about that.

MartyStrat54 · 10-17-2009, 11:36 PM

This might be a dumb question, but did you make sure you put the wires back in the correct positions? If the speakers are out of phase, you will get a thin, tinny sound.

You found the wires pulled before you ever played, right? Given that and the fact that the amp wasn't moved. I would say that you need to swap the wires around and see if that corrects your problem.

sugaragus · 10-18-2009, 12:10 AM

I'm such an idiot. You just made my night. I just switched them and it sounds perfect again. It's too bad that we played all night last night with a crappy sound, but I am sooo relieved.

Quick question - been playing 20 years but never learned technical stuff (obviously). Amp is model 4212. Previous owner put a greenback and a brithish speaker in it. I play smashing pumpkins type music. Which speakers should I put in there. also which tubes. I'm sure there's a forum for this and I can post the question there.

Again, THANK YOU so much for giving me that quick response to my stupid mistake.

MartyStrat54 · 10-18-2009, 12:37 AM

Here's where I hang out most of the time:

Preamp Tubes? - Who, What, When, Where, Why, and How?

There are several of us that would like to give you some suggestions on tubes.

I'm sorry, I don't understand what you meant by "British Speaker?" I will say that a lot of people are mixing speakers to get a fuller sound. Like tubes, there are so many speakers to choose from. The Pumpkins have a raw, midrange sound. I'm thinking V30's or Hellatone's.

Wilder Amplification · 10-18-2009, 03:08 AM

Quote:

Originally Posted by sugaragus

I'm such an idiot. You just made my night. I just switched them and it sounds perfect again. It's too bad that we played all night last night with a crappy sound, but I am sooo relieved.

Quick question - been playing 20 years but never learned technical stuff (obviously). Amp is model 4212. Previous owner put a greenback and a brithish speaker in it. I play smashing pumpkins type music. Which speakers should I put in there. also which tubes. I'm sure there's a forum for this and I can post the question there.

Again, THANK YOU so much for giving me that quick response to my stupid mistake.

For Smashing Pumpkins any blown speaker will do.

*sarcasm*

sugaragus · 10-18-2009, 12:38 PM

Marty: Yeah, that thread on tubes is helpful. I think I spent an hour on that thread and was only through the first few pages. I have a lot to learn but will pull my tubes and see what I have in there. I'm assuming it's the same for my Fender too.

Wilder - Good one!!

10-17-2009, 11:25 PM	#1 (permalink)
sugaragus Junior Member Join Date: Oct 2009 Posts: 13	Possible Blown Tube ?? Not sure Hello all. New to this forum but after looking through all the posts, there seems to be a lot of great information in here. My situation is this. I have an older JCM 800 combo, probably from the late 80's. Bought it a year ago and love the amp. I mainly just play in my basement with friends so the amp rarely gets moved. I went to plug in yesterday and noticed the 2 wires to 1 of the 2 speakers was disconnected. Possibly my cat was back there and pulled them out when he jumped out. I connected them back and when I play, the amp is missing all of that great Marshall sound. It's a very thin sound now and it sounds to me like a tube is blown. The 2 tubes I can see both light up and get hot. The other 2 have a blue casing and I can't tell. Can the problem have something to do with the wire connecters coming undone( I just put them right back on and doubt it) or can a tube be blown. How do i tell if one is blown so I know which one to replace. Thanks so much for any information. When we played last night I had to use my fender...what a let down as I hate that sound. Help me get that 'marshall' sound back. I know that's a long explanation...sorry about that.

10-17-2009, 11:36 PM	#2 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Possible Blown Tube ?? Not sure This might be a dumb question, but did you make sure you put the wires back in the correct positions? If the speakers are out of phase, you will get a thin, tinny sound. You found the wires pulled before you ever played, right? Given that and the fact that the amp wasn't moved. I would say that you need to swap the wires around and see if that corrects your problem. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-18-2009, 12:10 AM	#3 (permalink)
sugaragus Junior Member Join Date: Oct 2009 Posts: 13	Re: Possible Blown Tube ?? Not sure I'm such an idiot. You just made my night. I just switched them and it sounds perfect again. It's too bad that we played all night last night with a crappy sound, but I am sooo relieved. Quick question - been playing 20 years but never learned technical stuff (obviously). Amp is model 4212. Previous owner put a greenback and a brithish speaker in it. I play smashing pumpkins type music. Which speakers should I put in there. also which tubes. I'm sure there's a forum for this and I can post the question there. Again, THANK YOU so much for giving me that quick response to my stupid mistake.

10-18-2009, 12:37 AM	#4 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Possible Blown Tube ?? Not sure Here's where I hang out most of the time: Preamp Tubes? - Who, What, When, Where, Why, and How? There are several of us that would like to give you some suggestions on tubes. I'm sorry, I don't understand what you meant by "British Speaker?" I will say that a lot of people are mixing speakers to get a fuller sound. Like tubes, there are so many speakers to choose from. The Pumpkins have a raw, midrange sound. I'm thinking V30's or Hellatone's. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

10-18-2009, 12:38 PM	#6 (permalink)
sugaragus Junior Member Join Date: Oct 2009 Posts: 13	Re: Possible Blown Tube ?? Not sure Marty: Yeah, that thread on tubes is helpful. I think I spent an hour on that thread and was only through the first few pages. I have a lot to learn but will pull my tubes and see what I have in there. I'm assuming it's the same for my Fender too. Wilder - Good one!!

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