Boyk has assured my friend that there is no new tube topology under the sun, and he may be right, although I haven't seen this one before. I'm completing (I hope) a design right now that uses cathode-coupled pairs but no CFs per se, partially to address anti-CF prejudice but also as part of another trick. But such alternatives won't handle arbitrary loads, though you could get fancy and have real-time Z characterization (I'll let JR write that code :razz: ). If you know well your load Z you can do things to support the output current demands and unload the CF (or any other output) which always helps, and is potentially much faster than "Stasis" style topologies like the WF. The White follower probably compounds the higher order harmonic generation and is more global in its feedback, but I haven't seen any results or analyses. Here is an opinion (warning-a very messy translation) which if I read correctly suggests that despite the abundance of higher harmonic energy, with light loading and moderate signal swings the CF is satisfactory: I've done some CF designs with supertriodes and sand current sinks that I am told sound fine, and this from someone who pays a lot of attention to the buzz and if anything was prejudiced against the CF. (If it's been discussed before - and I suppose it has - just point me there.) īut really, at the heart of it, I don't understand the mechanism that would make a CF sound bad at all. Constant current only for small load currents, though: Which makes me wonder if I need a CF then, at all. Is there a known technical reason for that?Īnd if so, does it also apply to the WCF, or to CF with current source loading? I've seen one circuit that uses a transitor constant current source, and a transistor emitter follower to feed the CF's output signal to the anode, to have the CF tube working with both, constant current and constant voltage. And yet they are frowned upon by many "High End" audio builders. Which all makes sense from an impedance point of view. Or you see them as output stage of a HiFi preamp, to improove cable driving capability. And apart from loading them too much.įor instance, in phono preamps, you often see a CF between the last voltage gain stage and the volume potentiometer. Why do they have a reputation of sounding bad, and when do they sound good?Īpart from the obvious (bad design which makes them oscillate at RF etc.), I mean. I must admit I'm a little bit confused about cathode followers.
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