Hello, Dan,
Muir Woods is a gorgeous place--it would have been fun to be out
there with you with my DPA 4006TLs, UA0777 nosecones, and my
SD722...but, alas, I am now several timezones away in the Toronto area.
This is most intriguing. Of course, we have a myriad of factors here
that are influencing the end result and it's hard to isolate one from
the other. Here are some random thoughts on this.
We think -- at least from the spec sheets -- that the Sennheiser mics
are a little quieter than the ATs, but, if memory serves me
correctly, the 7xx recorders have quieter and better preamps than the
MP-2. I think SD thinks that the 788T has even better preamps
compared to the 744T and 722.
First question: Could you possibly have had the front-end pad engaged
on the Sennheiser mics? Only asking that because they were new to you
and you might have not checked it and the previous owner might have
been doing rock'n'roll. That would better match what you described noise wi=
se.
The other thing that occurred to me as that the equation here is
overall sound power in different bands. With the Sennheiser pair, you
have three "frontal" lobes in play while with the ATs you only have two.
Yes, I know the ATs are "omnis" but they aren't DPA/Nosecone omnis by
a long shot. If you look at their published polar patterns, I think
you'll find that they are down close to 5 dB 90-120 degrees off axis
at 5-8 kHz. So, in a diffuse field, I suspect you'll be seeing a
significant rolloff in these mics--and isn't the 360 degree ambience
of nature something like a diffuse field within a space? It's not a
reverberant field, but the crickets are all over the place chirping
away. So you'll get much more mid- and low-frequency energy in this than
Other than the nosecone approach, any compensation between diffuse
field and free field seems to mess up the response of the other. I'm
not saying the nosecone approach doesn't have its own set of problems
as I've been told over on the ProAudio list, but still it seems that
this "sound power" sphere that you have impinging on your mic will
have different response and that the total received power at 5 kHz
will be less than at 1 kHz.
Then there's the Jecklin Disk and I won't even attempt to figure out
what that's doing <smile>.
Just some thoughts to pass the time while your feet ache at NAB. I
did my 30 or so years at that show and don't really miss it, other
than dropping by and seeing people I know.
Cheers,
Richard
At 12:48 PM 2009-04-13, Dan Dugan wrote:
>...
>1) The Sennheisers were dramatically brighter in the upper-mid range.
>Maybe as much as four or five dB. The only standard for which was
>"right" would be comparison to a measurement mic.
>
>2) The Sennheiser/MP-2 combination had to be set at a higher preamp
>gain than when I use the MP-2 for 3032s, and was noticeably noisier. I
>was matching the -ambient- levels, which might not be fair to
>directional mics--but it was soundscape recording, after all.
Richard L. Hess
Aurora, Ontario, Canada http://www.richardhess.com/
Detailed contact information: http://www.richardhess.com/tape/contact.htm =
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