An actual amplifier problem
MissYouAllDay
Posts: 939
Today when I turned on my Hiwatt there was more crackling then usual. I turned it on in standby mode, left it for half an hour, tunrned it off standby, and started playing. There was an awful lot of crackling goin on. Or more than usual anyway. It always crackles and makes a few noises when first turned on.
Also sometimes when playin it will just cut out. The sound will ju7st stop and there will be a "pop" similar that of when you unplug ur instrument when it's turned on. What could cause this? I think it happens when I have just recently turned the amp on and hit a string really hard.
Also sometimes when playin it will just cut out. The sound will ju7st stop and there will be a "pop" similar that of when you unplug ur instrument when it's turned on. What could cause this? I think it happens when I have just recently turned the amp on and hit a string really hard.
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if your amp doesn't have one, you're probably screwed, unless you can get Matt Cameron (monkey) to look at it.
sorry dude
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This is my first tube amp.
Also is this a normal problem? The popping?
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ones not glowing first of all. then ones glowing too hot perhaps. it's not normal as far as i know. i'm far from an amp expert though.
The other place I'd check is any part of the speaker cable from the amp to the speaker that might be having an intermittent connection.
If your tubes are glowing a little hot, or it's been a while since they were changed, you may be due for a re-tube.
Just approximately.
I will fill you guys in on my speaker make too, I have been a little skeptical of it since the beginning.
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Well, I found info that says a DC40 has 4 X 12AX7, 1 X 12AT7, 4 X EL84.
You'll be looking at $10-15 a tube for the 12AX7's. Same for the 12AT7. The EL-84's you'll be ordering a matched quartet, will probably run you $40 for all 4. So, it depends... you could go with cheap tubes for about $70, or could go all out and get good tubes, spend $120.
My personal recommendation would be:
4 - Tesla JJ 12AX7/ECC83S x $9.95 = $39.80
1 - Electro-Harmonix 12AT7EH x $8.95 = $8.95
2 - Tesla JJ EL84/6BQ5 Matched Pair x $17.95 = $35.90
Total would be $84.65. Add about $5 for S&H, that puts you at about $90. The Electro-Harmonix tubes are my favorite, but I'm also a Fender guy, so they might not be your flavor (hence my recommendation of Tesla's). Sovtek are another good option, and tend to be a bit cheaper.
Go to http://www.thetubestore.com for more info.
I unplugged then replugged the speaker cable to the amp.
All the tubes are loose. But what is loose? LIke they all wiggle in their sockets, it kinda feels like they are just hangin there. It also seems as if I can't push them in any better. They are made out of glass so really how hard could you push them?
My speaker has no label on the back. Is that weird? Could it be a cheap speaker?
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The tubes should just be straight, not cocked to one side or anything. If your amp is an older amp (like, 30 years or more) you may need new sockets, but it's hard to say. Tubes usually are just a tad loose and can wiggle a little, unless the sockets are BRAND new. So yeah, just make sure they're straight and aligned correctly.
Do you spend a lot of time playing on half-power with it cranked? That can wear out those two power tubes pretty fast.
Does the speaker have any numbers on it? Like a serial number or ohmage? If so, what are the numbers?
K I have some new info. 2 of the 12Ax7's are glwing much dimmer than the other 2. All the EL 84's are glowing equally and are glowing a nice organgy yellow. The single tube seems to be glowing fine.
I thought maybe the two 12x7s werent glowing cause it was on half power, but I changed it to full power and watched it warm up. The same 2 tubes were still really dim. I wonder if this could be causing the problem of that werird pop occasionally.
The DC 40 has only been made since the 90's I think so I am not worried about the age of the sockets.
I am pretty sure the speaker has absolutely no markings on it. Is that weird or what? even 50 year old vibrochamps still have their blue labels stuck on the backs. The speaker output is set to 16horseshoe (WTF). Impendence.
I am gonna start a new thread for speaker talk cause I don't wanna get too much on my plate here.
So what you think?
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Start with the guitar plugged in, and wiggle around the cord. The cords are the most common problems with those noises. Make sure it does it with both different guitars, too.
A lot of those noises can be the guitar output jack having loose connections, a bad cord, or the amp input jack with bad connections
Then unplug the cord from the amp, and if it still does it, then it might even be a bad solder joint at the input jack. Definitely try a different cord, though.
You can take a stick or pencil and lightly tap on the tubes when it's on, too. If it's a loose tube socket, that might isolate it.
If that doesn't do it, then you can actually switch around the tubes. Look on the tube chart and switch similar ones for similar, but write down which one went where so you can put them back, especially the big ones. The small ones don't always glow brightly, so you can't go by that.
Don't do this if you aren't familiar though. It IS kind of easy, though. Pull them straight out. Just make sure the pins line up wih the sockets when you put them back in.
And those suckers get HOT. Don't burn your fingers! :eek:
If that doesn't make the noise happen, take it to a tech before you get new tubes. It might be a bad wire/solder joint inside the amp, too. When things expand and contract as the amp heats up, it can cause intermittant noises like that.
It might need a retube anyway if it's been played a lot, but I bet the noise is something relatively simple.
Good luck!
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2 of them are glowing fine, and two are undeniably dimmer. Not a tiny bit but barely even glowing.
The pop is the type of pop made when you unplug ur git while the amp is still on. The pop is caused by hitting the strings, not by moving around. Like it stops the sound dead when it hapens too. I will hit the strings (usually pretty hard when it happens) and then the pop. My GF in the next room thought the amp exploded.
So then there will be no sound of guitar, just the silence after the big pop. So it seems like definately a bad speaker or tubes cause it happens when I hit the strings hard and then is silent. It's not little pops or anything subtle like that. A big ass pop like you just took the other end of the chord unplugged it from the guitar, and hit your hand hard against it.
It is not a guitar or cord problem for sure. Never had a problem with other amps. Only happens when playing, and precisely when I just hit the strings pretty hard.
The first time I ever recall this happening I went to pound out the intro to highway to hell and pop, then silence. Scared the shit out of me
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I'm more inclined to believe that the two softer tubes are correct, and the two brighter tubes are bad. Preamp tubes shouldn't glow very much. But replace all 4, that's my recommendation. You could have them biased if you know a guy.
Thats why I figured the dim ones were fucked.
But what does a biasing do?
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Biasing adjusts the voltage fed to the tubes and makes sure the tubes are operating at the right speed. If you're going thru the trouble of re-tubing and you've never done that with the amp before, get it biased.
Well I will probably get my local guitar guy to take a look at it when I get home for abit.
But now that I tell you that all the tubes are pretty much uniformly bright except those 2 tubes do you think they are most likely the problem?
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About how much do you guys pay your techs for an amp checkup. I just wanna know so I have some Idea of whether or not I'm getting screwed around.
I am just gonna bring it in and tell him to look for the problem.
Thanks.
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