In looking at this high power jfet I wonder if it might be suitable for a small low impedance source follower in the 50 to 100ma range. Does anyone know if it would be very noisy when used like that with a 500 ohm source impedance ?
I was thinking about 5v 50 ma at 15v drain to source with a 500 ohm input source resistance at 1k hrz.
No.
50 mA idle current follower can't provide enough current to drive speakers.
It has a high transconductance and it must have a large die area, so chances are its equivalent input voltage noise level will be quite low. Current noise will be low(*) as long as you reverse bias the gate, which will happen automatically at 50 mA to 100 mA.
(*): Regarding noise current, a smaller JFET will be even better, but you will only notice that at very high source impedances, like those of condenser microphone capsules without built-in amplifier.
(*): Regarding noise current, a smaller JFET will be even better, but you will only notice that at very high source impedances, like those of condenser microphone capsules without built-in amplifier.
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In looking at the old Pass Bride Of Zen preamp it occured to me that it would be incredibly easy to modify it to a cascode using the Ld1014d like was done in the Zen 8. Heck with about 2.5v across the Ld1014d at 40ma it wouldn't even need any heatsink. I was just concerned with the noise. Wonder if it would sound better than the original.
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As it relates to the LU1014D, try as I might I can't get gain over 5x at 50mA in a simple config. Needs more gas, but will leave further analysis to another DIY member. Nonetheless, noise is very good and consistent with the results I wasn't happy with, in the sense that the 1/f corner is roughly the same.