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The gain of a standard cathode biased stage (bypassed cathode resistor) with a CCS plate load (assuming an ideal CCS of infinite impedance) is the mu of the tube. The plate resistance of the tube is removed from the gain equation. The varying Rp of the tube is responsible for much of the distortion. If you are looking for the classic "tubey" sound characterized by a lot of 2nd harmonic distortion; then a CCS plate load is probably not what your looking for. Some have characterized the sound with a current source load as solid state. I would disagree. My phono and line stages are fully differential. A true differential stage cancels even harmonics. So, I would say a triode stage with a CCS plate load sounds more like a differential stage without the common mode noise cancelation.
If your phono stage uses feedback, the open loop gain is part of the feedback equation. You change that you may have to change the values of other components to compensate. You could be affecting the RIAA equalization.
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
Caveat: my experience is with drivers for 2A3/300B DHSET power amps, which calls for high output voltages and thus greater distortion.
That said, I hear higher resolution of details and reduced euphonic coloration, with better bass slam and treble extension. If the power supply is noisy, a CCS load reduces that noise.
The balance between euphonic distortion and detail resolution is a matter of personal taste. I won't burden this thread with my personal choices/prejudices. :^)
nt
I hear the benefit of CCS loading in low current small signal operation where a large portion of the voltage swing resides in the curved part of the characteristic curve of the tube. I recently made a couple of active loaded tube condenser microphones and I was able to use a single LND150 and the effect or benefit is as clear as daylight. Yet I have also active loaded a preamp with 6N6p running a 20 + mA per tube and there was no real difference in the sound when I took it out. I also have a active loaded compressor with 5965 and 6N1p running strong for almost 20yrs and sounding better than the run of the mill tube gear.
not much difference, because I ran them with not much (little) current through them with 12ax7's, My Mistake!
Sorry TRE' I looked at the specs again and SOB, it was wrong of me.
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Have Fun and Enjoy the Music
"Still Working the Problem"
my apologies Tre', I will have to look it up again, I'm getting too old
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