Hi Phil-
Sorry. I think I may have confused your application with the 3032's
and the Mix Pre and Paul's.
Phantom powering could be a factor, but Paul seems to be connecting
his mics directly to the HDP2. If so, we're getting down to unusual
suspects. It seems unlikely that both 3032's would arrive at his
doorstep with _matching_ poor frequency response. That leaves cables,
recorder/recorder settings and the mic rig as suspects. The high
frequencies could be attenuated by essentially "blanketing" the mics
with excessive wind protection, but this would be inconsistent with
the lack of mic self-noise (hiss) in Paul's sample. I assume Paul's
HDP2 was at or near full mic preamp gain in that location.
Thanks for the nod about preserving low Hz content. In the sample we
are studying, the sonogram from Rich's "quiet" rural setting, shows
how much of the sound energy resides below 125Hz:
https://pantherfile.uwm.edu/type/public/media/RichAT3202_PaulAT3202.jpg
I suspect some recordists use the low cut filter to make it easier to
hear the high frequency content/calls in the field, but its possible
to bring home a fuller spectrum and still experience good monitoring
by using fully-enclosed headphones. Sennheiser HD280 phones, for
example, cost $90USD and provide about 30dB attenuation. Of course,
the low frequencies can always be shaped in post. Rob D.
= = = =
At 9:49 AM +0000 3/2/08, Phil Tyler wrote:
>Hi Paul
>
>Just a thought I have a pair of AT3032's which I use with a Sound
>Devices MixPre.
>
>I found that the MixPre became unstable when using AT3032's due to
>the way in which
>they work with phantom power. Most phantom power mic's vary the
>voltage they draw
>depending on the signal. AT3032's vary the current and this is what
>causes the Sound
>Devices MixPre the problem, due to the way it is itself powered.
>This low frequency
>instability was reduced using the LF cut on the MixPre.
>But I found another, much better, way around the problem, as the
>AT3032's are current
>and not voltage dependent they have quite a wide voltage range they
>can run on. So
>switching my MixPre to 15 volt phantom, rather than the normal 48
>volt and my problem
>goes away. As the MixPre's power supply can cope using the lower
>phantom voltage, and I
>can record without any LF cut, as Rob tells me I should :-))
>
>It may be your system is exhibiting a similar problem but not
>actually becoming fully
>unstable?
>
>Hope you find a solution soon.
>
>Phil
>
>--- In
><naturerecordists%40yahoogroups.com>
>Paul Jacobson <> wrote:
>>
>> Ok I guess I should post an illustration of what I'm getting.
>>
>> The whroo frogs recording which I posted to the list, and to which
>> John referred to, was made with LF cut on the HDP2 switched on. I
>> initially started recording with LF Cut off and had the recorder
>> running when I flipped the switch. There isn't much happening in the
>> recording apart from a bit of rustling, but it clearly illustrates
>> the kind of LF energy or "growl" that I'm trying eliminate.
>>
>>
>><http://www.urbanbirder.com.au/audio/play/13>http://www.urbanbirder.com.au/audio/play/13
>>
>> I'm trying to identify what is contributing to that LF energy. My
>> suspicion is that resonances from the tripod are being transmitted
>> into the rig, but looking at sonograms of Walt's comparative
>> recordings seemed to suggest that the might mic be a contributing
>> factor as well, but that could very well be a misinterpretation of
>> the recordings. I certainly wasn't condemning the AT3032's to the
>> junk heap - in fact I'm about to order another to use in a Telinga
>> Universal rig.
>>
>> I'm sure it's been stated many times, that these rigs are experimental
>>
>> The main reason I am looking at this is that I want to tweak/rebuild
>> the rig before I head up to the Alice Springs area in May for a
>> couple of weeks. The top priority is incorporating a shock mounting,
>> which I hope will eliminated much of the LF rumble/growl.
> >
>> cheers
>> Paul
>>
>>
>> On 02/03/2008, at 4:38 PM, Rob Danielson wrote:
> >
>> > Paul,
>> > Sorry to hear your AT3032's are not performing up to your
>> > expectations. I second John's suggestion. If you are certain the
>> > abnormal response or artifact lies in the lower registers, it would
>> > help to select a sound from (or record a test in) a quiet location
>> > away from low frequency sound sources. It common for locations to
>> > have lots of energy in this part of the spectrum. A wooden barrier
>> > can lift the upper mid-range and brighten-up the sound a bit, but it
>> > typically does not emphasize the lows. Of course, if you have other
>> > mics you can make recordings with in the same location/conditions,
>> > they'll will provide additional reference. Rob D.
>>
>
>
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