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Post subject: 1978 Super SF hum/buzzing
Posted: Mon Nov 28, 2011 4:40 am
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I just purchased an amazing super reverb, its the push/pull kind, and I think its the bomb. Anyway, after a couple of days of playing I turn iron only to hear a loud buzzing hum rather than the guitar. It happens when the guitar isn't plugged in too. Help!


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Mon Nov 28, 2011 7:17 am
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Hi Zowno,

Likely a bad tube, maybe an output tube, but could be any of the preamp tubes. Do you have known good spare tubes to try?

You should delete your other duplicate thread using the "X" at the bottom of your post, before someone responds. :idea:

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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Mon Nov 28, 2011 2:43 pm
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No I don't have any tubes to try, this is my first amp and I've only had it for 4 days :/


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Mon Nov 28, 2011 4:33 pm
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Buzz or Hum ? not the same
Hum is comming most of the time ,from the filter capacitors, or outputs tubes,

Buzz, come from preamp tubes or their circuit, like resistor.

First of all , is your buzz/hum change with volume, more volume more hum ?

1- If not , It look to be some filter capacitor need to be replace.
2- If yes, remove the first preamp tube. The one at right if you look amp in the back. Amp should be OFF.
3- Power amp ON ; No hum , replace for a new tube or problem in component around this tube.
4- Hum, remove also the second tube . Follow 2 and 3.

You can do these test on all 12AX7 and 12AT7 tubes until you find something. Not on power tubes. These tests with NO guitar


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 3:52 am
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I isolated the problem. The tubes are fine, its a problem with the reverb, any ideas?


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 4:24 am
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Zowno wrote:
I isolated the problem. The tubes are fine, its a problem with the reverb, any ideas?


Explain ......

Reverb problem are often the RCA plugs/ jacks need to be cleaned. Amp side and reverb tank side.


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 5:40 am
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What I mean is that with the reverb turned all the way down there is no loud buzzing. As you turn it up it becomes overwhelming. And I know it isn't just the amplification of the normal hum, this is so much worse


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 6:39 am
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Silverface amp have a problem with lead dress. Probably this is your case. Sometimes just move proper wire and noise will dissapear.


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 7:56 am
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In the Super reverb, the reverb is tube driven and tube recovered. :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: 1978 Super SF hum/buzzing
Posted: Tue Nov 29, 2011 8:21 am
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stratele52 wrote:
Silverface amp have a problem with lead dress. Probably this is your case. Sometimes just move proper wire and noise will dissapear.


Doubtful.

I'd look at a coupling cab in the V4 recovery circuit and check that tube for proper cathode current.

HTH

Arjay

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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Wed Nov 30, 2011 8:15 pm
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I have literally no idea what that means so ill just take it to an amp tech to get it worked out


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Thu Dec 01, 2011 3:09 am
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Zowno.
Be sure to see a really good tech if you don't want to loose your money


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Thu Dec 01, 2011 9:44 am
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stratele52 wrote:
Zowno.
Be sure to see a really good tech if you don't want to loose your money


+1!

(hint: they generally don't work at GC)

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1978 Super SF hum/buzzing
Posted: Fri Dec 02, 2011 2:31 am
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Well that's not a problem, I live in Australia, where there is nothing but boutique amp repairers :D


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