While the basic "super transistor diff pair" approach is sound, I see little benefits to going JFET input here. Quite the contrary, these are not cheap (you want LSK170s these days, as the originals are EOL and there's any amount of fakes around) and would have to be hand-matched for low offset. OK, RF immunity might be an issue and require some ferrite chokes/beads, but that's easy enough to test for. A few medium power bipolars are quite promising in terms of voltage noise, like BC337/327, 2N4401/4403. Those also have surface mount counterparts if need be, like BC817/807 and MMBT4401/4403.
With typical source impedances of 200-600 ohms differential, you won't have to go overboard in terms of voltage noise, like paralleled inputs or anything like that. With the gain control that's already present, you should have the threat of clipping covered pretty well - dynamic mics can output some surprisingly high voltages when subjected to high levels. One would have to look at the noise penalty of the setup.
You can do something neat with the trusty NE5534 opamp, namely tie its inputs to the negative rail and substitute an input pair of your own. Might be worth looking into. There's some Class A biasing options for the output as well.
With typical source impedances of 200-600 ohms differential, you won't have to go overboard in terms of voltage noise, like paralleled inputs or anything like that. With the gain control that's already present, you should have the threat of clipping covered pretty well - dynamic mics can output some surprisingly high voltages when subjected to high levels. One would have to look at the noise penalty of the setup.
You can do something neat with the trusty NE5534 opamp, namely tie its inputs to the negative rail and substitute an input pair of your own. Might be worth looking into. There's some Class A biasing options for the output as well.
Thank you very much sir. I understand what are you saying and i will try to put it into practice. One more question: DO you know/have/can recommend me some schematics to look into details further, or some "special" websites or blogs that treat this hi-end mic preamp approach?
Thank you again very much.
Kind regards
Thank you again very much.
Kind regards
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