Noise wise for sure. Note however that you actually would like to have gain as early as possible. This would ask for a different output stage topology though. Personally I'd go back to the Dorsey circuit I think (miccircuit.gif). Or do you see a specific advantage of your circuit?[/quote]Would the 2SK170 still be superior to the 2N3819 as a source follower?
Frequency response is not the problem, but the capacitors present a load to the output stage, causing frequency-dependent distortion.[/quote]Yeah, maybe the 22 nF at the output are a little high, although, according to spice, the frequency response remains flat to several hundred kHz.
That's good info, thanks. Ah, sounds like non-electrical mods there.Out of the box, the 3k version sounds kinda weird when plugged into a normal pre, which of course you only realize with a regular 200 ohms model (which is more like 300 ohms) for comparison. However, the weirdness is not just due to the transformer, but in part also due to some internal "improvements". With a few modifications the 3k version sounds waaaayyyyy better. Night and day difference. Out of the box, the standard version sounds is superior, so it's actually a good thing they returned to the original version. Except for modding.
I recall that thread, I feel I'm fairly aquainted with the guy that started it :wink: Lots of interesting discussions there, I saw it's from two years ago already.If you're scared to open the mic, you can build PRR's ribbon booster (in the "old" active ribbon thread). That circuit requires exotic super low Rbb transistors, though. .
Hmm, I understand & recall that, but there's also a nagging voice that says: "but plugging in the stock mic into a normal pre seems OK enough..."And by super low, I mean super low. Anything else won't do. That circuit is designed for normal low impedance ribbons and can be built into an external box or into the mic itself.
I would be interested to examine this further. Rossi, would you mind to send me some audio files? I'd need four of them (a pair for each FET configuration): one with a source at fixed level (e.g. pink noise from a loudspeaker) to calibrate the sensitivity of the microphone and one just with the self-noise of the microphone. 30 s each, 24 bit/96 kHz if possible.Then I used a 2N3819 instead and got slightly better results. The overall noise level may not have been lower, but there was less noise in the higher frequencies, where you hear it most. I've had excellent results with these 2N3819 before in condenser mics.
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