#1
Hey there everyone!


About 2 weeks ago, I was playing my amp full volume, the sound faded, and long story short I blew a fuse because it was on the wrong impedance (8 ohms when it should have been 16).


So, I replaced the fuse, changed the impedance to 16 ohms accordingly as it had specified to do so on the back of the amp cabinet, and everythinig was dandy.


Yesterday, the same thing happened. Again, I was playing full volume, and full gain. Then, the sound faded, and whatta-ya-know, blew another fuse.


Why does this keep happening? It's under proper impedance. The amp itself is practically brand new, only 1 or 2 months old.
Gear:
-Krank Krankenstein JR 50W
-Orange PPC112 w/ Celestion Vintage 30
-Gibson Les Paul Studio (white)
-Gibson Flying V
-MXR Carbon Copy
-Digitech Whammy
-Digitech JamMan
-Boss SD-1
-Epiphone Hummingbird
#2
A blow fuse is usually a sign of another problem. I have no idea what that problem may be though.
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#5
Bias your tubes.
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#6
Try playing in a different outlet.
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#7
get a fuse protector, its like 20$ at office depot i think, or it might be a surge protector for the outlet or something like that, but it works.
#8
Are amps even designed to be run at max volume? Just because the knob goes to 10 doesn't mean you have to, and if you do need to max it out wouldn't you have been better off with a more powerful amp. I can't imagine that opening it all the way up would be good on the tubes or the transformers.

I mean any time you push something to its limits it is bound to break, and if it has happened more than once when you push it that hard I think you may have the source of your failure.
#9
What do you mean by get my tubes biased? Like get them checked out by a tech or something?

The tubes should be fine, they're not even a month or two old, just like the amp itself. They all glow and have no marks to indicate they've been blown.

And I didn't think putting my amp at full volume would do anything. Because I agree, when things are pushed to their limits, they break, but so many people say they crank their amps at full and it sounds amazing, with no problems like this whatsoever.
Gear:
-Krank Krankenstein JR 50W
-Orange PPC112 w/ Celestion Vintage 30
-Gibson Les Paul Studio (white)
-Gibson Flying V
-MXR Carbon Copy
-Digitech Whammy
-Digitech JamMan
-Boss SD-1
-Epiphone Hummingbird
#10
Well if you were playing with a mismatched impedance there is a good chance that your power tubes were getting fried in the process. They maybe a month old but there is a reason why people tell you to match impedances. Under loading an head will cause 1) stress on the powert tubes and 2) OT to overheat. Be glad that all that happened was a blown fuse. Next time you fire up your amp check your tubes for redplating. Where the gray plates start glowing. If they are then they're toast. You need to swap them out.

Quote by WenisWeasel
What do you mean by get my tubes biased? Like get them checked out by a tech or something?

The tubes should be fine, they're not even a month or two old, just like the amp itself. They all glow and have no marks to indicate they've been blown.


How do you know the tubes should be fine? It doesn't matter how old they are, particularly if you were running a mismatched impedance in which you really don't know how much strain you put on them. Depending on how they're biased, they could be fine they could not be. I've fried a power tube in SECONDS before biasing an amp for the first time.

Just because the tubes light up doesn't mean they're working, and if you keep blowing fuses, I'd take that as an indication that they might be bad. Just because you can't SEE any damage (though redplating is usually a pretty good indicator of bad tubes) doesn't mean they're good. A blown tube can look the exact same as a good tube.

And biasing means setting a safe idle current on the plates. Your amp puts a high voltage on the plates and tubes can only dissipate so much heat before they're toast.
Last edited by al112987 at Dec 21, 2008,
#11
If this happens when you play the amp really loud then I'd say your poweramp is failing under the pressure. It's possible the output tubes are bias too hot.
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#12
Thank you VERY much for your help, it was very informative.

So to bias it, I should take it to a local technician then, and maybe replace the tubes?
Gear:
-Krank Krankenstein JR 50W
-Orange PPC112 w/ Celestion Vintage 30
-Gibson Les Paul Studio (white)
-Gibson Flying V
-MXR Carbon Copy
-Digitech Whammy
-Digitech JamMan
-Boss SD-1
-Epiphone Hummingbird
#13
$20 says your power tubes are already toast. I'd check for redplating, but I wouldn't really run the amp as bad tubes often short and it can damage other components in the amp. Chances are your amp was already biased correctly, but when you're running a mismatched load then you're killing your tubes (along with your OT, which is a much bigger deal, but some OTs are more robust and can handle a 100% mismatch, others not so much). Regardless yes, you will need it to be rebiased when you re-tube it. Take it to a (good) tech and have the whole thing checked out.
Last edited by al112987 at Dec 21, 2008,
#14
I got an idea STOP TURNING IT UP TO FULL VOLUME theres only a few amps u can do that and itll function try mesa, peavey maybe or u no dial back ur volume or get a bigger amp and dont use the volume so much example get knobs that go to 11 then use them at 10
#15
Quote by JessyB96
I got an idea STOP TURNING IT UP TO FULL VOLUME theres only a few amps u can do that and itll function try mesa, peavey maybe or u no dial back ur volume or get a bigger amp and dont use the volume so much example get knobs that go to 11 then use them at 10


Care to explain why? Please don't drop "advice" like this without backing it up. Diming an amplifier is perfectly fine. You realize that they have devices called attenuators for the sole purpose of being able to crank your amp at low volumes? You'll go through power tubes a little quicker but that is about it. Besides, if an amp doesn't function at "11" I don't see how turning it to "10" would make function any more.
Last edited by al112987 at Dec 22, 2008,
#16
I am probably wrong but my reasoning behind it was that amps are rated by their RMS wattage. So lets say you have 50watt amp everything in the amp is rated to work with no problems at 50watts, but you open it up to 10 and leave it there and the amp is now pushing its max power which will almost always be higher that what they are advertised at. Now you are exceeding the safe tested area of the components and eventually something is going to have to give.

That was my logic its probably wrong.
#17
Quote by Demigawd
I am probably wrong but my reasoning behind it was that amps are rated by their RMS wattage. So lets say you have 50watt amp everything in the amp is rated to work with no problems at 50watts, but you open it up to 10 and leave it there and the amp is now pushing its max power which will almost always be higher that what they are advertised at. Now you are exceeding the safe tested area of the components and eventually something is going to have to give.

That was my logic its probably wrong.



The wattage rating is the (rms) power output before some percent distortion is observed, it has nothing to do with "safe limits." If it was a safety thing, amplifiers would not be designed to operate beyond their power ratings, my JTM45 breaks its "30 watt" rating by the time it hits 5 on the dial. Claiming that only a few amps are functional being run at 10 (and being condescending about it to boot) is completely wrong.
#18
Like I said I was probably wrong, and I guess I was

Oh well gotta learn somewhere.
#19
the last time my amp kept blowing fuses was because of it being biased wrong and because the was a bad tube socket check both of those
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#20
Quote by JessyB96
I got an idea STOP TURNING IT UP TO FULL VOLUME theres only a few amps u can do that and itll function try mesa, peavey maybe or u no dial back ur volume or get a bigger amp and dont use the volume so much example get knobs that go to 11 then use them at 10


I just lol'd so hard at this.
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F/S:
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