rogs
Well-known member
The OPIC circuit is pretty much as simple as things can get...... It's a unity gain impedance converter, with no extra gain stages - or even non essential resistors - in the signal path. That helps to keep the noise down.Hi, thanks to Mic Scharf and Rogs for the great project!!! I also ordered a set of circuit boards and built them in BM 800 housings and the jli 2555 capsules. The noiselevel is very low, pretty cool. I find the used JLI capsules are bit too bright.
Does anyone have an idea where in the circuit you could implement a reasonable de-emphasis of the highs? A few dB less in the highs above 8kHz would be a bit better.
This Opic circuit is imo almost indistinguishable in a direct parallel comparison with a Schoeps electret circuit on a PCB from VAMI and these JLI 2555 capsules. Not really bad...
Where it doesn't work so well is when you consider adding internal EQ. That would not only be a bit of a major rethink, it would add extra components in the mic itself. .... Extra components in this early part of the signal path will add noise, in addition to doing what you hope the filter will do!
Also, adding a simple single order low pass filter is a bit brutal..... Yes, it will attenuate the offensive 'bright' mid range boost -- but also everything else above that !
If you're recording, then adding EQ in your DAW in post is probably a better answer. Much more subtle in controlling specific parts of the frequency range.
If you're doing things live, then you might like to look at the option of adding EQ - at line level - further along the signal path?
( I made some notes on cheap hobby versions of that idea HERE )
Simplest and best of all is k. brown's idea - fit a better capsule. I've found JLI's shipping costs make their products pretty expensive outside the USA.
If you want to add a capsule that will really change the character of the mic, you might look at Arienne Audio capsules? ..
Bit expensive maybe? -- but really good IMHO.
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