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Post subject: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 9:20 am
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What's up Guys?

Help me solve a mystery!

So I have a Fender '59 Bassman Reissue, got it in March, love it. It's the tone machine of my dreams. My basement is setup as a fully-functional jam room, with my gear, a bass rig, a drum set, and a PA. Awesome. I've been jamming with a trio for a couple of months with no problem at all.

About a week ago my wife and son were out of the house at some event at my wife's work - I didn't have to go. So I figured I'd fire up the rig and let it rip. After about 45 minutes I started getting this CRAZY hum out of the Bassman. Fired it up a few days later, when the rhythm section was over for a quick jam. For the first hour, everything was great - then the buzz came back. We pressed on, and I just overwhelmed it with sheer volume, lol. You could only really hear the hum when I wasn't playing.

On both occasions I tried unplugging the amp and bringing it up to the living room and the problem was immediately fixed; but the band and I can't jam on two separate floors obviously.

With my limited knowledge of how buzzing electronic gremlins and poltergeists work I tried to diagnose by isolating the possible contributing factors; none of which helped fix the problem once it had started:

1. I tried a variety of instrument cables

2. Tried two different guitars (single coil Strat & humbucker LP) and a bass (active pups). Tried all pickup positions on all 3 instruments.

3. I only have incandescent lights down there, no flourescent bulbs. But I turned all the lights off anyway.

4. Turned my cell phone off and put it upstairs.

5. Tried plugging the amp and effects board into 2 different power strips and also directly into 2 different outlets.

6. Tried it both through the effects board and straight to the amp.

7. Tried turning the amp off and giving it 15 minutes to cool off, then turning it back on.

8. Tried each input on the amp individually (Normal and Bright), AND both at the same time.

I can only imagine I'm picking up some kind of interference somewhere, but I can't identify where. It didn't happen at all before last week, and it only seems to happen after 45-90 minutes' worth of playing. It's always nice and quiet at first. The other weird thing is the louder I turn up the Amp volume (or overdrive pedal) the louder the interference gets, but the louder I turn up the GUITAR volume (either the Strat or the LP) the quieter the hum gets, but it never fully goes away.

So yeah, guesses and suggested solutions certainly welcome, lol. I was considering ordering the retube kit from Eurotubes, because I eventually do that with ALL my amps anyway. Is there a way to "shield" an amp?


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Post subject: Re: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 9:54 am
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Have you tried rotating similar tube types to various sockets? Or a known good tube into various positions? Have you checked the output tube bias?

May want to try contact cleaner on the sockets & tubes. And jacks.

Anyhow, I'd rule-out tubes and connections, first.


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Post subject: Re: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 10:06 am
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Misterboston1 wrote:
and it only seems to happen after 45-90 minutes' worth of playing.


I suspect a thermal issue with one or more components, likely an electrolytic cap in the filter array or bias supply.

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: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 2:07 pm
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Aspiring Musician
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If you took the amp upstairs and the hum went away,...I am suspecting interference of some kind coming from somewhere,...but where is the question. Are there any computers nearby in the house? I'm curious as to what it is in such a rather new amp. You said you had regular style light bulbs down in your basement. I have serious doubt the amp is defective,...is the humming you hear like an AC line hum,or some other type of hum?
And it only appears after 45 minutes or so of playing?

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If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


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Post subject: Re: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 3:32 pm
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Are you able to run an extension cord to the upstairs outlet just to see if the hum is still there? Use a good heavy cord. If the upstairs outlet is on a different breaker, it could just be interference from the basement run somewhere.


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Post subject: Re: '59 Bassman Reissue - HUM!
Posted: Tue Jun 17, 2014 3:57 pm
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Aspiring Musician
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Joined: Sun Jan 27, 2013 3:44 pm
Posts: 366
upnorth wrote:
Are you able to run an extension cord to the upstairs outlet just to see if the hum is still there? Use a good heavy cord. If the upstairs outlet is on a different breaker, it could just be interference from the basement run somewhere.


That sounds logical,...and could very well be a source of his hum he's getting! I would almost lay bets on that! He's getting interference from somewhere in the basement wiring,...it has to be! If it runs fine upstairs without any hum at all,...then has it in the basement,what else could it be? If he's running wireless mics on the PA system,he could be getting RF interference,too,...but way he describes it,...it sounds more like wiring in the basement run! Being a ham radio operator,I know about dealing with interference,...especially RF interference.,and sometimes electrical interference!

_________________
If it aint' broke,...don't fix it! I like to keep my amps and guitars factory original,...no mods necessary,...don't want them,...don't need them!

My gear as of now;
Standard Strat
Hot Rod Deluxe III amp
Champion 20 amp
'59 Bassman LTD Reissue


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