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 Post subject: Tube Amp Problem
PostPosted: Thu Mar 17, 2011 10:57 pm 
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Joined: Sat Dec 04, 2010 5:41 pm
Posts: 549
Location: Sonora California
I have a Pignose g40v that was a combo amp that somebody converted into a head only.

The problem is, it was stored for a long time. I took it out and played it. Eveything was fine. The pots were kinda scratchy. The volume was plenty loud in my house at 1 or 2.

The next day I brought it out and played it and all the volume is gone. I have to turn it to 10 to get it almost as loud as it was at 1 or 2 the day before.

I rolled it from one room to another and back, but beside that I didn't touch it or anything.

What's the deal?

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 Post subject: Re: Tube Amp Problem
PostPosted: Thu Mar 17, 2011 11:05 pm 

Joined: Mon Dec 20, 2010 1:27 pm
Posts: 193
sounds like a tube blew


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 Post subject: Re: Tube Amp Problem
PostPosted: Fri Mar 18, 2011 3:15 am 
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Posts: 549
Location: Sonora California
I was kinda thinking that from what I've read. They both are glowing orange, but maybe they should be brighter? Would they burn at all if there was a problem and needed to be replaced?

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 Post subject: Re: Tube Amp Problem
PostPosted: Fri Mar 18, 2011 3:26 am 

Joined: Sun Dec 05, 2010 11:54 am
Posts: 987
I have a Fender 140 head that would eat tubes for breakfast--volume being gone is definetely most likely a sign of a bad tube. Tap the tubes--if they start to freak out (squeal) or if you hear tapping at all, then it's a tube--that's the cue that it's become microphonic. If it's a preamp tube, it's significantly cheaper. If it's a power tube, it will be a bit more expensive, since a 40 watt amp most likely has two power tubes (EL34, i'm guessing?) and it would be advisable to replace them in pairs, as it's a better idea overall to have matched sets of tubes because the cathode current will be the same. You don't have to replace both of them, but you'll get better sound and performance out of replacing them both. I usually deal with The Tube Store--insanely fast shipping, the tubes are always in top shape, and they match the pairs.

http://thetubestore.com/


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 Post subject: Re: Tube Amp Problem
PostPosted: Fri Mar 18, 2011 11:56 am 
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Joined: Sat Dec 04, 2010 5:21 pm
Posts: 208
Location: Springfield, MA, USA
I'm assuming you plugged directly into the amp with no pedals to check it, right?


One time, I thought I was having some amp problems, and it turned out to be an input level on my space echo. Ha! I plugged in directly, and I thought my house was gonna crumble from the volume. Oops...

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 Post subject: Re: Tube Amp Problem
PostPosted: Fri Mar 18, 2011 1:50 pm 
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Posts: 549
Location: Sonora California
Yes, I tried directly in. Tried different cords. Different guitar, the usual stuff...

I tapped on the tubes and I can hear them very faintly if I put my ear up to the speaker. It doesn't get any louder if I turn up the volume. It sound like I'm tapping on a glass. Would it make no sound at all through the speaker if the tube was good?

Looks like they're 6L6 tubes.

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 Post subject: Re: Tube Amp Problem
PostPosted: Tue Mar 22, 2011 3:36 pm 
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Location: Albuquerque, NM
Two questions:

1) I see you're using the 4-ohm output. Does the speaker cabinet match this?

2) Are you using a speaker cable rather than an instrument cable to connect the head to the cabinet?

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 Post subject: Re: Tube Amp Problem
PostPosted: Tue Mar 22, 2011 7:59 pm 
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Location: Sonora California
Yes to both of those questions sir.

I suppose I'll just roll the dice and order a couple tubes. It's cheaper than taking it to someone for repair. If it does not solve the problem, I can still take it in and I'll always have use for the tubes at some point.

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 Post subject: Re: Tube Amp Problem
PostPosted: Wed Mar 23, 2011 10:43 am 
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Joined: Sun Dec 19, 2010 4:47 pm
Posts: 13
My guess is a blown capacitor, pretty common for them to dry up when you haven't used your amp in awhile.....


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 Post subject: Re: Tube Amp Problem
PostPosted: Wed Mar 23, 2011 12:25 pm 
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Joined: Sat Dec 04, 2010 5:41 pm
Posts: 549
Location: Sonora California
Quote:
My guess is a blown capacitor


Damn, that's the other likely things I've read in searching the web. I don't have any idea how to go about that.

I have another tube head that has a bad transformer, I'm gonna check if it has the same tubes and switch 'em out to see if it makes a difference.

*edit* Well, the other amp is a Sunn Sorado and the tubes are WAY bigger in that thing, so I won't be swithing those out.

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Last edited by tastelikedirt on Sat Mar 26, 2011 11:30 am, edited 1 time in total.

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 Post subject: Re: Tube Amp Problem
PostPosted: Fri Mar 25, 2011 5:48 pm 

Joined: Sun Dec 05, 2010 11:54 am
Posts: 987
tastelikedirt wrote:
Yes to both of those questions sir.

I suppose I'll just roll the dice and order a couple tubes. It's cheaper than taking it to someone for repair. If it does not solve the problem, I can still take it in and I'll always have use for the tubes at some point.


Yeah, you can get a pair of Sovtek 6L6's for pretty cheap, so that may be a good idea. If that doesn't solve the problem, possibly it could be a preamp tube....the worst that can happen is that if it's not the tubes, at least you've forced yourself to buy some new ones, anyways--never hurts to start off fresh in a new (old) amp with some new tubes, just in case....


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