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Post subject: Fender Super Sonic 60 Hum
Posted: Mon Dec 12, 2011 7:00 pm
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Hello, I recently purchased a fender super sonic 60 that was used for about a month from my local music shop. I was playing if for a few weeks and decided to record a track with it. It wasn't until then I noticed a hum on the clean channel, its not very loud but definitely heard in the recording. I was wondering what could cause this? I have a friend who has an older model that does not hum at all on the clean and on the burn channel I get the hum from the distortion (which is normal) and the constant hum I hear on the clean channel. I know it is not my guitar because I hear it with nothing plugged in and it doesn't start humming until the amp get warmed up for about 5 minutes. I also watched a YouTube video of the same amp in a demo and there was no hum just the white sort of noise of it being turned on. any suggestions? any help is appreciated.


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Mon Dec 12, 2011 9:35 pm
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Hi Bromosapien,

It might be typical 60 Hz hum. How did you record, with something connected to the amp, or with mic? Was the amp moved to a new location? To start, I would disconnect all external equipment from the amp, to isolate the amp to see if something is introducing the noise to the amp. Make sure that the outlet the amp is plugged into, has a proper ground. Maybe even try a previously used outlet when you had no hum.

If the problem is definitely with the amp, it might be a bad tube, output or preamp. Also, check if any different with reverb turned all the way down. Usually the easiest thing to try, is substituting known good tubes. You can use one 12AX7 to try in each preamp spot, one position at a time, to see if it is a preamp tube issue. Next try a known good set of output tubes, making sure to set the bias with each change of output tubes.

Just a few suggestions. :idea:

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Tue Dec 13, 2011 2:59 am
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+1 Shimmilou


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Tue Dec 13, 2011 2:23 pm
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Quote:
Hi Bromosapien,

It might be typical 60 Hz hum. How did you record, with something connected to the amp, or with mic? Was the amp moved to a new location? To start, I would disconnect all external equipment from the amp, to isolate the amp to see if something is introducing the noise to the amp. Make sure that the outlet the amp is plugged into, has a proper ground. Maybe even try a previously used outlet when you had no hum.

If the problem is definitely with the amp, it might be a bad tube, output or preamp. Also, check if any different with reverb turned all the way down. Usually the easiest thing to try, is substituting known good tubes. You can use one 12AX7 to try in each preamp spot, one position at a time, to see if it is a preamp tube issue. Next try a known good set of output tubes, making sure to set the bias with each change of output tubes.

Just a few suggestions.


well i called my local shop and it is still under warranty so if it is anything that needs servicing its free and also it makes the hum when nothing is plugged in and my friend has virtually the same amp with no hum so i'm starting to think its a bad ground or a faulty tube i'm going to plug it in somewhere else to double check but i'm pretty sure my house is grounded properly.

[UPDATE] I recently found a set of finger prints, well I wouldn't say burned into but more like visible from the heat on the logo of the main power tubes which proves the owner before me was fiddling around with them at one point because as I recall you are not supposed to touch them with your bare hands because the grease can burn the tube so my best guess is that one of the power tubes is going because sometimes I hear a pop and light crackle for no reason or when I flick the standby switch sometimes it also pops.

Also, I plugged the amp into an outlet that I know for a fact has been grounded because that section of my house was redone recently and I know the plugs were grounded so that's also ruled out i'm taking it down to the shop to see what's going on


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Tue Dec 13, 2011 4:23 pm
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OK, good job, it does seem like a tube issue, pop and crackle (not mentioned before), I would say preamp. The warranty for the amp is five years, but the tubes are only covered for ninety days.

Forget the myth about touching the tubes with hands, it's not a problem. Generally you don't want to change tubes while eating ribs, but touching the tubes with your hands can only harm your hands, if tubes are hot. The tubes are not the same as HID light bulb where fingerprints are a problem.

Let us know what the tech finds, or if you change tubes yourself. :idea:

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Tue Dec 13, 2011 4:35 pm
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Finger print on a tube is a ( light ) problem . It is not a good habit to have tube with finger print. Clean glass help to evacuate heat.


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Post subject: Re: Fender Super Sonic 60 Hum
Posted: Tue Dec 13, 2011 7:58 pm
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Ok i'm taking it in probably this Saturday I will post the techs feedback I appreciate your guys help thanks!


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