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Author Topic: California Hummin'  (Read 10135 times)

Frank DeWitt

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Re: California Hummin'
« Reply #10 on: May 29, 2014, 04:19:45 pm »

Frank - thanks for your insight, electrical connection and Bill's paper. Great reading.

Short of getting an electrician to hunt down the problems in my house when connecting a 49 year old tube amp to the wall socket, what would you suggest as a quick fix - or for other venues where the $5 Home Depot checker says the outlet is OK, but the amp buzzes? If there's a better solution for these things, I'm all ears.

We can get some help from the experts on the list but lets get started.

Does the amp have a 3 wire cord?  at 1965 vintage I wouldn't expect it to.
Does it hum with nothing connected to it?
I assume it only hums when the Guitar is plugged in. If that is true, is anything else connected to the guitar?  Pedals ETC.
 
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Ned Ward

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Re: California Hummin'
« Reply #11 on: May 29, 2014, 05:10:49 pm »

Frank - thanks for your questions.

Amp in question is a 1965 Fender Bandmaster. 3-prong plug installed, death cap wiring removed and new electrolytic filter caps installed with full amp overall/rebuild.

Amp buzzes with nothing plugged in  -- in our house - I did the POE by taking guitar, pedalboard, and finally just instrument cable out of the equation.

If I take it down to my amp repair place that rebuilt it, no buzzing at all.

Plugging it into the Hum-X at home removed the buzz.
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Jeff Bankston

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Re: California Hummin'
« Reply #12 on: May 29, 2014, 09:53:23 pm »

when i had to replace my burnt out incandescent light bulbs with GE cfl's i got buzzing and hum in the stereo and geetar amp that i didnt have before.
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Jerome Malsack

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Re: California Hummin'
« Reply #13 on: May 30, 2014, 01:54:14 pm »

In the old home stereo days with two prong plugs it was advised to plug in two devices and with out connecting the two to measure the voltage from Frame A to Frame B  Then flip the plug 180 and insert and repeat the measure for lowest voltage. 

When working a guitar, 1/4 line cord and amp you should not see the hum unless the frame of the amp is connecting to the live hot wire.  this would be similar to having the live hot wire connecting to the screw part of the light bulb and not the center pin on the bottom. 

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Kevin Graf

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Re: California Hummin'
« Reply #14 on: May 30, 2014, 02:16:59 pm »

when i had to replace my burnt out incandescent light bulbs with GE cfl's i got buzzing and hum in the stereo and geetar amp that i didnt have before.
One Ham radio operator found a burnt-out CFL light in his basement (he thought that it was turned-off). Anyway it was creating all kinds of interference.
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TJ (Tom) Cornish

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Re: California Hummin'
« Reply #15 on: May 30, 2014, 02:30:15 pm »

In the old home stereo days with two prong plugs it was advised to plug in two devices and with out connecting the two to measure the voltage from Frame A to Frame B  Then flip the plug 180 and insert and repeat the measure for lowest voltage. 

When working a guitar, 1/4 line cord and amp you should not see the hum unless the frame of the amp is connecting to the live hot wire.  this would be similar to having the live hot wire connecting to the screw part of the light bulb and not the center pin on the bottom.
Um, there may be other issues if the amp chassis is tied to the hot wire.  :o

Any guitar amp repair shop that lets an amp out the door without a grounded 3-wire plug and appropriate life-safety modifications needs to go out of business.  I presume that Ned's person was competent enough to modernize the grounding.
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Jerome Malsack

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Re: California Hummin'
« Reply #16 on: May 30, 2014, 02:41:11 pm »

I agree but it still happens. 

http://www.frankdoris.com/writing/tas/setup.htm

paragraph 5 of making the connections. 
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TJ (Tom) Cornish

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Re: California Hummin'
« Reply #17 on: May 30, 2014, 02:49:08 pm »

I agree but it still happens. 

http://www.frankdoris.com/writing/tas/setup.htm

paragraph 5 of making the connections.
With respect, that article is utter BS on several levels.  They are advocating defeating plug polarization, among other things.  Various audiophoolery exists in several other places.
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Ned Ward

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Re: California Hummin'
« Reply #18 on: May 30, 2014, 03:04:05 pm »

Um, there may be other issues if the amp chassis is tied to the hot wire.  :o

Any guitar amp repair shop that lets an amp out the door without a grounded 3-wire plug and appropriate life-safety modifications needs to go out of business.  I presume that Ned's person was competent enough to modernize the grounding.


Totally agree Tom. "vintage amp specialists" that don't want to replace the power cord or remove the old "death cap" wiring are considered idiots in my book. My guy modernizes the grounding, uses a 3-prong cord, new electrolytic filter caps. He then gives me the old parts in a baggie in case I sell them and some idiot wants all the original parts. I play mine regularly, and having had a 1960-something Hilgen Basso Grande that shocked me more than once, I'll never play one of these without ensuring it's not going to zap me.


Reminds me to take my guy my 1950's Bogen amp (Challenger CHA-33) to have him look over the 3-prong cord installation and ensure the grounding scheme is correct there… Thanks Tom!
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Art Welter

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Re: California Hummin'
« Reply #19 on: May 30, 2014, 04:46:22 pm »

If I take it down to my amp repair place that rebuilt it, no buzzing at all.

Plugging it into the Hum-X at home removed the buzz.
Have you checked your home outlets to determine there are no hot/neutral swaps ?
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Re: California Hummin'
« Reply #19 on: May 30, 2014, 04:46:22 pm »


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