Dan
I don't remember the source of my opinion on this, but I've always had it i=
n mind that the MKHs have their noise spectrum 'shifted' upwards so that th=
ere is less audible noise in the very noticeable 3-5kHz range.
For this reason, and despite their excellent HF response, I've always disco=
unted them as good mics to record extreme HF for pitching down in post beca=
use all that noise will be transposed into the audible bands along with the=
signal.
I'd be interested to see if the boost switch increases the noise along with=
the HF.
Ben
--- In Dan Dugan <> wrote:
>
> A few weeks ago someone, I think it was David Brinicombe, mentioned obser=
ving HF noise in Sennheiser MKH 20 microphones. I've noticed it too, when l=
ooking at a spectrogram of a quiet environment.
>
> This morning we did a comparison of a 3032 next to an MKH 20 on the carpe=
t of an interior room, covered with some blankets. The diffuse-field HF boo=
st switch was in the flat position. I used the preamps in a Sound Devices 7=
Message: 44T.
Subject: I posted an expanded-scale picture of the resulting spectrum at:
>
> http://www.dandugan.com/downloads/Nature_Sounds_Photos/AT3032_v._MKH_20_n=
oise_via_744T_preamps.png
>
> Red is Sennheiser, green is Audio-Technica. The down-sloping curve on the=
left is obviously ambient noise. I tried to match the levels at around 500=
Hz. I believe that above 1K we are probably seeing mic self-noise plus pre=
amp noise. The "hiss" from the MKH 20 is obvious. I put hiss in quotes beca=
use I can't hear this noise at all. It isn't trivial however. I see that up=
-sloping top end in recordings from quiet locations.
>
> The tonal artifacts in the 3032's spectrum, especially in the range 400-1=
KHz are curious. They could be from the mic or the preamp, not investigated=
yet.
>
> My first guess is that the MKH 20 might be equalized in its electronics t=
o compensate for a naturally rolling-off HF response of the capsule.
>
> -Dan
>
|