Cutting low frequencies on Mic

[The Dude]

Glad you found something that works for you.
That is the problem with a totally passive circuit. There is no way to boost signal. Any alteration of signal requires cutting.
If you're feeling ambitious, you could also build an active high pass filter using a low noise op amp or FET to keep the mic gain up. This will be a bit more complicated as you'll also need to come up with/build a power supply for the FET or op amp and it's a bit more involved circuit wise.
All that said, it seems like you've already solved your problem.

[jjj]

I was just looking for some audio recorder with real-time Mic filter, for I used Sony's Sound Forge, but it only allows somewhat "cleaning up created mess"... No good, is it?

Also, I noticed Sony's Sound Forge "Classic Wave Driver" with Creative Lab's Sound Blaster "What U Hear" adjustment has Mic latency, because it's created by Sony's Sound Forge recording the later. - At least Sony's Sound Forge "Direct Wave Driver" offers me no latency. Life isn't meant to be easy!

[The Dude]

The absolute best way to do this would be to get multi-track recording software. Record your mic on a totally separate track and process it after it's been recorded. That will give you full control over the whistling track and you can use a host of audio plugins to process the track- compressors, filters, EQ's, reverbs, and anything else you like. If you search the web, there is plenty of freeware recording software. Sound Forge is mastering software and is not meant for multi-tracking.

[Steve Conner]

I like Reaper. You're supposed to buy a license for $60, but the free trial never expires, it just puts up a nag screen now and again. The plugins it ships with are very usable.

[jjj]

Yes, I too only use this kind of "welfare goodies" on my PC and leave the other type to millionaires. I'm looking for an audio recorder with real-time filter/ plugins.

[jjj]

Yes, I have tried that too with Cakewalk etc., but for that I would need to buy a full-blown PC, not laptop. I had that before with the $250 Sound-Blaster Audigy4 Pro.
Yet, the result in sound quality was about the same I'm getting now with this lousy $30 USB-Stick soundcard. It's incredibly small, yet sounds so good!
In fact, the only improvement on my whistling with music recording setup, would offer an effective recording software with real-time filters/ plugins.
Otherwise I just stick with this aluminum shield... and keep on the lookout for the former.
From the aluminum shield test recording (located in reply #4 of this thread) you can hear that the breathing noises are actually not that bad; rather lend authenticity to the recording.
After all, the whistling has been "humanly" created and not by a machine. Even whilst performing in public, I had a number of mugs claiming that I'm an impostor; i.e. not whistling at all! Ones an elderly, apparently "normal looking man", walked up to me and said: "It's about time that you stop making a fool of yourself. By now we all know that you are miming and it doesn't look good on an elderly man..." What a nut!

[jjj]

Thank you for this good hint. Yes, that one is very much I now have with this Sound Blaster USB sound card stick and pretty affordable, too! - I'll keep an eye on that...
The problem with it ...still is that they don't have real-time filters, which allow me to adjust/ setup the Mic before a recording.
The only other way is to buy or build myself a low noise Preamp or Mic EQ to attenuate undesired frequencies and then plug in the Mic into these USB sound cards.

[jjj]

Yes, I checked Reaper v4.32 and did some recording with it. It offers indeed a host of filters, but there too the problem with it ...still is that they don't have real-time filters, which allow me to adjust/ setup the Mic before a recording. The only other way is to buy or build myself a low noise Preamp or Mic EQ to attenuate undesired frequencies and then plug in the Mic into these USB sound cards.
Besides, this (welfare edition of) portable Reaper sports "Commercial Licence" and so, works without nags... better don't update it (!) I can upload it for you...