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Post by fisholot on Jul 28, 2007 21:35:27 GMT -7
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Post by dixiechicken on Jul 29, 2007 2:24:29 GMT -7
Looks slick - no experience.
Cheers: Dixiechicken
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Post by myles on Jul 29, 2007 11:31:29 GMT -7
All these things do the same thing but it looks nice enough.
I have never seen or used one of these personally.
When there are all sorts of slick displays and options to my thinking there is more to fail. Any good toolbox already has a meter so I tend to stick with a basic bias tool and use my own meter.
As far as calculations, I prefer to do my own.
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Post by benttop (Steve) on Jul 29, 2007 11:49:47 GMT -7
Not much to calculate if you have a one ohm resistor in the cathode path. .030 volts across that resistor is .030 amps. That's 30 milliamps if you move the decimal point.
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Post by myles on Jul 30, 2007 9:46:41 GMT -7
Not much to calculate if you have a one ohm resistor in the cathode path. .030 volts across that resistor is .030 amps. That's 30 milliamps if you move the decimal point. There you go! Then again, some folks want to know where that 30mA spec came from. Some folks also want to know what 50%, 60%, etc., dissapation is for a particular tube at a given plate voltage.
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Post by benttop (Steve) on Jul 30, 2007 10:11:47 GMT -7
Not much to calculate if you have a one ohm resistor in the cathode path. .030 volts across that resistor is .030 amps. That's 30 milliamps if you move the decimal point. There you go! Then again, some folks want to know where that 30mA spec came from. Some folks also want to know what 50%, 60%, etc., dissapation is for a particular tube at a given plate voltage. Ah yes, THAT arithmetic!
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Post by billyguitar on Jul 30, 2007 11:04:50 GMT -7
Looked great until I saw the price. Another reason I like cathode biased amps.
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Post by myles on Jul 30, 2007 11:15:10 GMT -7
There you go! Then again, some folks want to know where that 30mA spec came from. Some folks also want to know what 50%, 60%, etc., dissapation is for a particular tube at a given plate voltage. Ah yes, THAT arithmetic! For the math and a list of dissapation values and test spec settings for some of the common tubes so I have this data anywhere I am near a PC go to www.guitaramplifierblueprinting.com/index2.htmland .... at the top right corner of that page is a little red button with no label .... it will download and XLS sheet to your PC that you can save and use. The basic sheet originally came from Duncan Amps but I modified it in number of ways. Myles
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Post by fisholot on Jul 30, 2007 11:25:25 GMT -7
Nice spread sheet myles, thanks.
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Post by nitehawk55 on Jul 30, 2007 11:59:44 GMT -7
I have a compu-bias Erik . In a word.....excellent ( in my best Mr. Burn's voice ) ;D I know they are a bit pricey compared to others but it's nice seeing the plate voltage , ma's and watts the tube is putting out . To me if something in any of these area's is really off then you know something is not right . They are a long term investment item that with proper care will last you for years . I remove the 9V battery from mine when not in use .
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Post by myles on Jul 30, 2007 13:35:47 GMT -7
Nice spread sheet myles, thanks. You are quite welcome
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Post by myles on Jul 30, 2007 13:39:36 GMT -7
I have a compu-bias Erik . In a word.....excellent ( in my best Mr. Burn's voice ) ;D I know they are a bit pricey compared to others but it's nice seeing the plate voltage , ma's and watts the tube is putting out . To me if something in any of these area's is really off then you know something is not right . They are a long term investment item that with proper care will last you for years . I remove the 9V battery from mine when not in use . Reading the plate voltage easily is a big feature. Sticking a probe into a socket has it's disadvantages as you can zap yourself and to do this you need to remove the tube which in turn gives you a higher reading as the power supply is not loaded properly. Sticking the probe on the bottom of the socket with the tube installed has a few more issues. One .... electocution ... two ... hitting the probe someplace else and perhaps shorting the meter or blowing the meter fuse or shorting something in the amp. And ... using this method means pulling the chassis. These bias tools that give the plate voltage have that cool feature that is paid for very fast when it keeps from damaging something or shocking you
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Post by myles on Jul 30, 2007 13:41:33 GMT -7
I have a compu-bias Erik . In a word.....excellent ( in my best Mr. Burn's voice ) ;D I know they are a bit pricey compared to others but it's nice seeing the plate voltage , ma's and watts the tube is putting out . To me if something in any of these area's is really off then you know something is not right . They are a long term investment item that with proper care will last you for years . I remove the 9V battery from mine when not in use . Erik ... one more thing here .... unrelated .... Your avatar ..... if you listen to Buddy Whittington your statement hits a golden nail on the head with a jewel encrusted hammer for being dead on accurate in your caption
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Post by fisholot on Jul 30, 2007 20:33:58 GMT -7
Well I guess like everything there seems to be advantages and disadvantages. But I think for me I would be safer with it rather than just poke'n around inside waiting for some sparks... Thanks guys....
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Post by fisholot on Jul 31, 2007 19:59:22 GMT -7
I pulled the plug and got one on the way..
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