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perhaps another stupid question....


 
5/2/2003 5:07 PM
Andy
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perhaps another stupid question....
in the tube data I've been looking at for 6550/KT88 tubes, for a 100-watt push-pull class A amplifier, it lists 100ma of plate current at idle and 280ma at full signal. is this current the sum of the two tubes together, or is it what each tube is drawing? it would appear that it could be either way.
 
5/2/2003 5:20 PM
tommy
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Look up at the heading of the data section. It should say values are for 2 tubes.  
 
So anyway, each tube idles at 50mA for a total of 100mA. At max power each tube is pulling 140mA for a total of 280mA.  
 
Chris
 
 
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5/2/2003 6:02 PM
Andy
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the data I was looking at was the NJ7P site, and it doesn't make that declaration.
 
5/2/2003 7:37 PM
tommy
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Okeydokey.  
 
This is a scan of the original. It's got the ref.  
 
http://www.triodeel.com/6550ap3.gif  
 
The ones that confuse me are the Amperex sheets where it says "2x100mA", which supposedly means "2 tubes draw a total of 100mA" but looks like it would mean "2 tubes draw 200mA". Those Crazy Dutch! :D  
 
Chris
 
5/2/2003 7:16 PM
Chris ( CMW amps )
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"100-watt push-pull class A amplifier, it lists 100ma of plate current at idle and 280ma at full signal."  
 
muest be class AB1 or AB2 :) . Class A amps do have the same idle and full-output current .  
Most of the time there are notes in the data-sheets about the measuring-conditions , like "values for two tubes" .  
 
Chris
 
5/2/2003 8:23 PM
Andy
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obviously, you're talking about average current, as it stands to reason that if there's a varying ac signal applied to the grid, the current is going to rise and fall with the peaks and valleys of the signal.
 
5/2/2003 8:37 PM
Chris ( CMW amps )
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Andy  
 
The max. outputpower ( in theory ) from two 6550s is 42 Watts . For 100 watts you really got to put them in class AB1 or AB2 .  
 
fwiw  
 
Chris
 
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