Hi Rob,
Thanks for your helpful advice. I had a chance to listen to my set
up out at my parents place - which is marginally quieter than where I
live. It was a fairly calm day and it was apparent that the vast
majority of the LF was being generated by distant traffic. It wasn't
apparent to the unassisted ear but was all too audible when
monitoring. Given the comparative distance to major roads at my
parents, I'm now thinking that the major freeway in a small valley
some 2km distant and reasonably busy roads 1km from where I live
would be major contributor of LF on the test recording I made a few
days ago.
I'm probably so used to using the LF cut that the actually levels of
LF energy are a bit of a shock!!
I'm still convinced that there is some resonances being transmitted
into the rig in winder conditions. When using the same tripod with a
scope in windy conditions the vibrations from the tripod are visible,
so I assume this vibration would be passed into the rig. I'm going to
try building an isolated base for the rig to eliminate this
potential noise source.
cheers
Paul
On 03/03/2008, at 8:07 AM, Rob Danielson wrote:
> At 7:02 AM +1100 3/3/08, Paul Jacobson wrote:
>> Ah,.. The nose-dive in frequency response your sample shows starting
> at 4KHz (see green line on the right most chart)
> https://pantherfile.uwm.edu/type/public/media/
> RichAT3202_PaulAT3202.jpg
> suggests to me that either the setting you recorded does have high
> sound levels from 125 to 4K Hz or the mics are deficient in the
> high-end. The former is more likely with matched results.
>
>
> There usually are massive amounts of low hz energy because these
> sounds have the power required to travel great distances. Without
> knowing exactly what I'm listening to, its hard to be certain, but I
> don't hear anything strikingly abnormal about the lowest octaves in
> your sample (2nd half of:
> https://pantherfile.uwm.edu/type/public/media/
> RichAT3202_PaulAT3203.wav)
> The low end tonal structure (left side of
> https://pantherfile.uwm.edu/type/public/media/
> JacobsenAt3032_Sono_Flat_RolledOff.jpg)
> looks pretty normal to me. Faint standing tones and bounciness below
> 125Hz from background presence is quite common.
>>
>> If the HDP2 has phantom powering issues with the AT-3032, that
>> might
> show up in a web search. Do you have any way to try the mics on
> another recorder or power them with a portable phantom supply like a
> Rolls PB224 or Art Phantom III?
>
> If the mics have poor high-end response, I bet you would have noticed
> it when you put on the headphones in the field. Rob D.
>
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