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Topic: Biasing a Tube Amp |
Craig Bailey
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Posted 29 Jan 2021 4:45 pm |
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Anyone have any sort of guide for biasing a Fender tube amp?
Thanks
Craig
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Mullen G2, Mullen Discovery, GFI D10 Ultra,
'76 Rosewood Emmons PP, '79 Black Emmons PP
Telonics Amp, Stereo Steel, Fender Vibrasonic & many Telecasters (You can't have too many) |
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Russ Wever
From:
Kansas City
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Bill Hatcher
From:
Atlanta Ga. USA
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Posted 29 Jan 2021 11:33 pm
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| Set your meter to dc ma. Use the center tap of the output and pin three of the 6l6. 30ma per side for two 6l6 and 60 ma per side for four. If you are not experienced with using this method then buy you a bias kit so you don’t have to take out the chassis and deal with the high voltages. You can pull the tubes,insert the kit,reinsert the tubes and safely read the bias without removing the chassis. The adjustment pot is accessed from underside. Easy and safe. |
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Craig Bailey
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Posted 30 Jan 2021 4:36 am
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Thanks Bill. Sounds like the bias kit is the way to go.
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________________
Mullen G2, Mullen Discovery, GFI D10 Ultra,
'76 Rosewood Emmons PP, '79 Black Emmons PP
Telonics Amp, Stereo Steel, Fender Vibrasonic & many Telecasters (You can't have too many) |
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ajm
From:
Los Angeles
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Posted 30 Jan 2021 7:58 am
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Your profile says a Fender Vibrasonic, but your actual post does not specify which amp(s) you are asking about.
Some amps are much easier and safer than others.
Since we don't know your level of experience with amps and electronics, my advice initially is DON'T do it yourself.
If you are near a major city/town, find someone that will do it for a small cost, and maybe they will also show you how to do it.
Depending upon your knowledge level, it's not difficult.
But there are several little gotchas that can quickly turn into one big GOTCHA. |
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Michael Butler
From:
California, USA
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Craig Bailey
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Posted 30 Jan 2021 10:01 am
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Thanks for the thoughts guys. I have a few different tube amps that need to be biased from time to time. I appreciate the help.
Craig
_________________
________________
Mullen G2, Mullen Discovery, GFI D10 Ultra,
'76 Rosewood Emmons PP, '79 Black Emmons PP
Telonics Amp, Stereo Steel, Fender Vibrasonic & many Telecasters (You can't have too many) |
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Tim Whitlock
From:
Colorado, USA
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Posted 30 Jan 2021 10:08 am
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I have recently begun to learn how my beloved vintage tube amps work and how to maintain them, including how to bias the tubes and what it all means. One of the first things I learned is you can't understand things like tube biasing without some basic electrical knowledge.
I have been reading books and using Google, but the Uncle Doug Youtube videos have been invaluable in helping get me firmly grounded (no pun intended). He explains things in clear, precise language sprinkled with his entertaining dry humor. I highly recommend his video series where he gives tutorials in basic electrical theory, as it applies to tube amplifiers, and tackles troubleshooting and resolving problems with a variety of vintage tube amps. Here is a sample of one of his basic tutorials.
https://www.youtube.com/watch?v=x5SSKX74DKg
WARNING: Once you get into his series, you may find yourself incessantly consuming one after another like salty chips and your wife will be wondering what you're doing in front of your computer for hours on end. |
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Tom Wolverton
From:
Carpinteria, CA
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Posted 3 Feb 2021 10:48 am
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Yes. The Uncle Doug videos are very excellent.
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To write with a broken pencil is pointless. |
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Larry Dering
From:
Missouri, USA
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Posted 3 Feb 2021 2:31 pm
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| The Uncle Doug teaching is the best option. |
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Dave Meis
From:
Olympic Peninsula, Washington, USA
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Brian LeBlanc
From:
Falls Church, Virginia, USA
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Posted 4 Feb 2021 3:29 pm Doug's your Uncle
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Man, you weren't Kidding !
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'Frenchy' LeBlanc...
ShoBud & Twins |
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John Macy
From:
Rockport TX/Denver CO
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Posted 7 Feb 2021 9:24 am
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For us solid state guys, it’s more like “shall we go bias some beers a little late?â€
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John Macy
Rockport, TX
Engineer/Producer/Steel Guitar |
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Jerry Erickson
From:
Atlanta,IL 61723
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John Limbach
From:
Billings, Montana, USA
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Posted 26 Feb 2021 5:41 am
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| An easy circuit mod for most push-pull, grid biased tube amps will allow you to bias each tube individually. No need to buy a "matched pair", or a new tube at all unless the bias gets extreme enough to push one tube or another off the linear portion of its characteristic curve. |
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Jon Zimmerman
From:
California, USA
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Posted 26 Feb 2021 12:04 pm Tall Order
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| Uncle Doug is the best ‘gateway’. Books (and vids) from Gerald Weber, Aspen Pittman (RIP) should be your reference ‘bibles’. Like most every tech exercise, it’s a learning curve. Only shortcut is to find a local, reliable, experienced, affordable shop situation. Good luck. |
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Liam Sullins
From:
Brookville, Ohio
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Posted 26 Feb 2021 7:31 pm
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How I learned right there!
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'66 Sho~Bud Fingertip, Sho~Bud amps, Fenders, old cars and Tinkerin with steels! |
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