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Post by edoetsch on May 16, 2008 13:39:43 GMT -7
I have a Bias Rite and have used it to swap tubes a few times.
Is it OK to have them in between the amp and tubes and to play at high volumes?
I ask so that I can try out different bias setting (low/high etc.) without hurting anything. Or is it really just an idle current probe?
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Post by Deleted on May 16, 2008 20:02:33 GMT -7
Just an idle current probe. You don't want to play through it.
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Post by amakitalo on May 17, 2008 9:22:12 GMT -7
Why not?
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Post by bluzman on May 17, 2008 10:15:35 GMT -7
I think it's due to what Doc sez in his Bias Notes. You're basically setting up the "idle". You wouldn't adjust the idle on a car when you are moving, shifting and raising and lowering the RPMs. Here is the excerpt from the Dr. Z Amps page from the Bias Notes: "...The simplest way to think about biasing output tubes is to use an analogy of your car’s idle adjustment. To optimize the performance of your car, the idle speed in RPM must be adjusted correctly. If it is too high you’ll need to apply more pressure to the brake pedal when stopped at a light, RPM’s will be too high and your car will want to race. If the idle is set too low, the car will want to stall because the RPMs are too low. This is the same with your output tubes. Bias too high and the amp will sound a bit harsh and distort too quickly, and will lose all focus at high volumes. If the bias is too low the amp will sound cold, brittle, and at higher volumes will have excessive crossover distortion, will sound dissident, and your guitar will sound out of tune."www.drzamps.com/biasnotes.htmlAlso go to the Myles of Tube Resources Page for a great education. His Tube Primer is a must read for anybody that even swaps tubes. www.guitaramplifierblueprinting.com/index2.html
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Post by Deleted on May 17, 2008 17:02:36 GMT -7
I really can't give ya' a good explanation other than I emailed Myles with the same question a few years back and he said not to do it, something technical I believe.
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Post by amakitalo on May 18, 2008 13:36:20 GMT -7
I always set the bias at idle, or volume at 0, however, I do listen to the amp with the probe on just to make sure it sounds ok after biasing it. So, I am not supposed to do this?
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Post by Ed M. on May 18, 2008 18:24:33 GMT -7
I always set the bias at idle, or volume at 0, however, I do listen to the amp with the probe on just to make sure it sounds ok after biasing it. So, I am not supposed to do this? I hope Myles chimes in because I do the same thing.
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Post by myles on May 19, 2008 9:33:39 GMT -7
You actually can do this but the reading will go up very high and on some tools may go past their design limitations. It depends on the tool and the one to talk to is the maker of the tool.
I also do not like having extra components incircuit that are not designed to be there. There is more chance for arcing as there are more tube sockets under the tube with high voltages on pins 3 and 4.
I would not do this myself but you won't blow up anything if you do not exceed the current rating of the resistor in the bias tool and to know that you have to talk to the maker of the particular device.
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Post by Deleted on May 19, 2008 13:15:21 GMT -7
You actually can do this but the reading will go up very high and on some tools may go past their design limitations. It depends on the tool and the one to talk to is the maker of the tool. I also do not like having extra components in circuit that are not designed to be there. There is more chance for arcing as there are more tube sockets under the tube with high voltages on pins 3 and 4. I would not do this myself but you won't blow up anything if you do not exceed the current rating of the resistor in the bias tool and to know that you have to talk to the maker of the particular device. Thanks, Myles. You're expertise is much appreciated.
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Post by myles on May 19, 2008 18:32:43 GMT -7
You actually can do this but the reading will go up very high and on some tools may go past their design limitations. It depends on the tool and the one to talk to is the maker of the tool. I also do not like having extra components in circuit that are not designed to be there. There is more chance for arcing as there are more tube sockets under the tube with high voltages on pins 3 and 4. I would not do this myself but you won't blow up anything if you do not exceed the current rating of the resistor in the bias tool and to know that you have to talk to the maker of the particular device. Thanks, Myles. You're expertise is much appreciated. You are quite welcome
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