Topic: high pass filter betwen the capsule and themic body

[oleg]

question ,
is it  possible to build high pass filter between the capsule and the preamp body ( mbho mics and similar)?

[oleg]

i dont want permanently change it  but place 1  as cut 1 on schoeps which is active device , thats why i ask
if it possible at all ?

[DSatz]

oleg, the CUT 1 takes advantage of the particular contact arrangement built into all Schoeps CMC-series microphone amplifiers, with a ring on the input connector designed to accept the output of an active accessory (an active cable, active extension tube, active gooseneck, BLM 03 C capsule or CUT 1 or CUT 2 active filter).

Since that arrangement was patented by Schoeps back in the 1970s, the other microphone manufacturers who introduced their own detachable capsule systems all had to come up with other, different arrangements. So you would need to build your filter into whatever fits your particular microphone amplifier's contact arrangement. (If you're using Neumann's KM 100 series, they offer an alternate output stage called the KM 100 F with high-pass filtering built in.)

As a less drastic alternative, if your phantom-powered microphones consume more than 2 mA each, you could consider using Schoeps LC 60 in-line filters, which have 18 dB/octave slopes and a 60 Hz turnover point. They also make an LC 120 filter, but 120 Hz is too high a corner frequency for most music applications. I have a pair of them, but only use them occasionally for speech recording in rooms that have a lot of rumble.

During the late 1990s Audio-Technica offered a nice, inexpensive ($45 US) 18 dB/octave active filter called the AT8683 with an 80 Hz turnover point. Like the Schoeps, it was for phantom-powered microphones and took its own powering from the phantom supply in the line (with some minimum current requirement such as 2 mA). They don't make it any more, but maybe you could find a pair of them somewhere.

--best regards

P.S.: Shure apparently still makes their A15HP in-line 12 dB/octave passive filter. It doesn't have as sharp a cutoff as you can build into an active filter (the Schoeps CUT 1 is 24 dB/octave fixed at 70 Hz, plus one variable pole), but it's still a lot better than nothing when you need something! See http://www.shure.com/ProAudio/Products/Accessories/us_pro_A15HP_content. Note that these passive filters add some distortion at low frequencies and high signal levels--not as much as Shure's overly conservative specs say, but still some. With condenser microphones in some situations, one might need to be careful.

[oleg]

thanks

yes  i had a feeling that as active device it is not possible

thanks , i will check what would come cheaper , buy 2 lc  60 or ask mbho for 2 low fq  roll of fixed 603 bodies :-)
the roll off is for the boom work , i prefer to cut the lows before it goes  to preamp .