Posted by Forty2wo [ 71.242.6.171 ] on July 16, 2005 at 20:46:26:
In Reply to: Fixed Bias v. Cathode Bias posted by manualblock on July 16, 2005 at 14:43:25:
Hi M, (sorry I forget your real name)
The main claim to fame of fixed bias, is efficiency, you get more power out of a set of tubes if you are not heating up a cathode resistor. But with FB you are applying a voltage, aka (signal) to the grid. If this is not deep black it will be heard.
With CB you will have a certain amount of degenerative feedback , which is not a bad thing and my guess is that is what you ( and me ) are hearing
With CB often you are running you tubes deep into "class A". You can test this. Measure current across the cathode resistor . then when you switch to FB set the current to the same or more.
Try this and tell me what you think…John
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