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Post by myles on Aug 13, 2008 15:11:39 GMT -7
I was asked about how the wattage of my own KT-45 was calculated. This is the method I use on all amps:
1000 hz tone into an 8 ohm load resistor with a voltmeter and scope connected to the resistor .... raise the level until clipping just occurs. Tone controls set to the most clean waveform at 400 and 1000 hz. My load resistor is a 250 watt load resistor. KT 45 = 22.8 volts into 8 ohms = 64.98 watts at the onset of clip. If you have an HP distortion analyzer you look for 5% or 10% (depending on whose spec you want to use) distortion level and measure the voltage and apply Ohm's law to calculate wattage.
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Post by jbgtr on Aug 13, 2008 20:03:54 GMT -7
Thanks again Myles!
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Post by myles on Aug 14, 2008 7:50:09 GMT -7
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Post by Phil (aka Phil) on Aug 14, 2008 10:33:42 GMT -7
For those of you that haven't been through Electronics 101 the formula is: voltage squared divided by the resistance.
;D
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Post by myles on Aug 14, 2008 13:09:20 GMT -7
For those of you that haven't been through Electronics 101 the formula is: voltage squared divided by the resistance. ;D Phil ... Thanks ... I probably should have pointed that out You can also do the same thing using this sort of example 20 volts / 8 ohms / 20 volts = 50 watts or as Phil said .... 20 squared = 400 / 8 ohms = 50 watts
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Post by edoetsch on Aug 18, 2008 21:28:02 GMT -7
I assume that test is with the SS rectifier.
Ever test with Tube Rectifier? Can we assume a tube will be approx that same?
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Post by myles on Aug 19, 2008 8:45:15 GMT -7
I assume that test is with the SS rectifier. Ever test with Tube Rectifier? Can we assume a tube will be approx that same? My results on the KT45 were always with the tube rectifier. With a solid state rectifier, if all is the same ... output tubes and phase inverter, you may see a rise of 3-5 or so watts in some cases over a production rectifier as most of them are on the weak side.
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