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Plate voltage and power output - how do you choose?

6/19/2000 2:59 PM
Plate voltage and power output - how do you choose?
I posted this over on Weber's amp board a couple of days ago and no one responded, so maybe it's really stupid question. I've looked over the other info as much as I can, but I just don't have enough knowledge (damn little) to grasp the whole relationship between plate voltage and power output. My HR50 has 500 volts on the plates. I gather from reading posts that this is on the high end for 6L6 type tubes. I remember reading a post stating that the Sovtek 6L6WXT tubes sound good with a plate voltage of 420, but I can't remember where the person set the watts at DC idle. Someone answered my post from last week stating where they liked to set the bias for the 6L6WXT's (in m.amps), but never said what their plate voltage was. Wouldn't this matter? I have an amp where I can put in a solid state rectifier, a GZ34 or a 5U4 to give me 460, 440 and 420 on the plates respectively. I want to play with different output tubes. I have Svet 6L6's now with the GZ34 and a 5751 for the phase inverter. Nice and clean. I do the math and see that the recommended bias setting gives me about 14.5 watts at DC idle. Now if I change the plate voltage with a 5U4 I can go from 33ma to 35ma to get the same watts at DC idle. How does plate voltage affect the sound, what makes you select a certain plate voltage, how do you know how many watts at DC idle is good for a given tube? Thanks to anyone that can help me understand this. In the meantime I'll keep fumbling through the tech pages and see if I can get anything more. Thanks.  
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