Tube Amps / Music Electronics
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|previous: Ray Ivers Momo,
|5/29/2000 4:22 AM|
|dutch||Re: Cathodyne PI|
>You have to make certain that the phase
>inverter is properly biased, but this
>method has the advantage of presenting
>very little loading to the output of the
>preceding gain stage, allowing you to run
>a higher value of plate load resistor for
>more gain if necessary.
Actually, with a typical common cathode stage found in most guitar amps, the DC voltage is a little bit high, and will bias the cathodyne so that one side clips sooner than the other. Switching to a higher plate load resistor in the common cathode stage (assuming its cathode resistor is left alone) helps line the DC up better for the cathodyne, in addition to giving a bit more gain.... Sounds like a "win-win" to me.... :^)
BTW, I've seen an old circuit with a cathode follower DC-coupled to the plate side of a cathodyne phase inverter, so that both phases have a low impedance cathode-driven output. I guess this makes the amp work a bit more symmetrically when at the onset of clipping, since both sides have a fairly low impedance source driving them, rather than just one side.... I haven't tried it yet, but it does look interesting.
|momo Thanks for the response! What is a... -- 5/29/2000 4:40 AM|