Cascode Buffers

[acoustixman]

acoustixman,
I would go for fully balanced topology.

Thanks for the tip; that simple schematic makes good sense and helps my conceptualization; comprises 2 drive stages ultimately then- one per output terminal. Doing this with a unipolar supply appears pretty trivial... which could be nice in cases of using a simple step-up converter and avoiding AC coupling frequency response coloration. For example AUTO sound...

 

[traderbam]

I'd say we fully agree with just one caveat of mere opinion... I prefer to remove the requirement for power supply regulation via design of the amplifier itself. I agreed when I heard it said once by an audio 'pundit' (G. Randy Slone if I recall) that a regulated power supply doesn't necessarily do better than an amplifier at providing PSRR in principle...

I don't know how Halcro regulate their supplies, but I imagine they do it pretty thoroughly. Even if PSRR is not the point, Q5 & Q6 still provide a small CMRR benefit. There may be other benefits that would take more time to flush out. I very much doubt that Halcro put those transistors in there without very careful consideration. Lesser brands, maybe!

That's what brought me to my initial question; the merits of cascoding on the basis of referencing the signal waveform (representing something like a ripple influence, however "congruent" to the signal itself). My conclusion has become: If Miller effects and associated impedances are accounted for and/or minimized in the bandwidth of interest, biasing cascodes relative to the signal waveform can be made practicable to the end of containing the gain transistors at INDEED constant Vce. This of course based on assuming it is approached in a way that does not load or affect the input signal source.

Sure.

True that is. I'd also like to do/see a simulation of this at some point. Now, to get around to acquiring some user-friendly simulation software somewhere...

This is excellent and free: LT Spice

 

[Lumba Ogir]

acoustixman,
try again and do a more rigorous conceptualization, please. Underestimating would be a serious mistake...

 

[traderbam]

Here's another configuration to consider, JW. This is some unidentified op-amp schematic I found. This appears to provide a dual function cascode, one to minimize Vce variation and the other to servo the base current, thus boosting input impedance.