Alright, I'm planning on building an RIAA MM preamp using 2SK170 JFETs with resistors and not CCSs. I just need advice on what type of psu I should use, basically only two JFETs per channel and they'll run of +36V. I gather they'll have to be regulated, but would a discrete regulator be that much better than say a integrated shunt one like the TL431? If so I haven't seen any suitable discrete designs, I was thinking maybe a pi filter followed by a discrete zener shunt regulator. Or would a series regulator be better? Or should I even bother with the pi filter? Maybe just a C filter, if so how large? So many questions, I've never built a discrete transistor circuit that uses resistors instead of CCSs so I just don't know how quiet the suply has to be, thanks as always for any replies though.
In general, design for a much "quiet" as you can - especially in a preamp stage, as any noise here is going to be amplified by everything else. I even like to see an LC filter from the transformer to reduce current spikes and, thus, noise.
The pearlphono design looks pretty good and, with some tweaks, should work fine at 36 volt output. Some of the newer integreated circuit voltage regulators ought to work pretty good, too, and should give lower a lower Zout and possibly better hi frequency response. A good old emitter follower with a zener on its base ought to work good for a low current amp as well.
So many choices!
The pearlphono design looks pretty good and, with some tweaks, should work fine at 36 volt output. Some of the newer integreated circuit voltage regulators ought to work pretty good, too, and should give lower a lower Zout and possibly better hi frequency response. A good old emitter follower with a zener on its base ought to work good for a low current amp as well.
So many choices!
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