Topic: High Frequencies In Outdoor Recordings

[raymonda]

Mshlarious,

According to your recordings, I stand corrected regarding my statement on the effect of outdoors and overtones reducing the high end in this recording. Apparently, it is more due with off axis position of the mic.

Thanks for your time, effort and correcting this mistake.

How about going back 20 feet and recording the violin and see how the overtones and fundimentals compare. Which most likely may replicate the recording situation.



 

[chris319]

mshilarious -

Could I ask you to post the spectral analysis plots for the low mic and high mic separately, rather than overlapping them (a total of four gifs)? Thanks.

[newplanet7]

Even though a lot of what is
displayed in this thread goes over my head,
I love these threads.
I can grasp a chunk of it at a time, so thanks
for your time fellas.
+t

[chris319]

Lemme do a rerecord and then I'll post the .wavs later today.

Well?

[boojum]

I am just dumber than a box of rocks so I cannot posit; I have to test.  Try the same mics indoors and see how they capture sound.  If they work fine, it is the venue when recording outside.  If not - which I doubt - it is some other thing.

One test is worth a thousand opinions.     

[chris319]

Again, I would like to know what acoustical phenomenon makes air such an effective low-pass filter when recording outdoors. Right now I am subscribing to the notion that it was mic position. I will have another shot at these strings on Monday night, but they will be indoors and my mics will be up high. Still, I am keeping in mind about the shortcomings of a LDC at high frequencies.

[boojum]

My guess is that the "acoustical phenomenon makes air such an effective low-pass filter when recording outdoors" is cockpit error.  If it were anything else it would be well known and the mic manufacturers or field users would have a ready fix for this.  The almost non-existent reporting of this problem makes me think it is what I have suggested.  Review your procedures.

If it is something else, as you believe, I sure hope you can clue us in on it.

[chris319]

If it is something else, as you believe, I sure hope you can clue us in on it.

You haven't been paying attention, either. The current theory is mic placement/angle relative to the instruments.

[Brian Skalinder]

You haven't been paying attention, either. The current theory is mic placement/angle relative to the instruments.

FWIW, that's my take, too.

Out of curiousity, what mic configurations were you using for omnis?  cardioids?

Edit to add:  How big / wide was the ensemble?  Proximity to lower frequency instruments may have contributed to their more dominant sound in the recording.  DSatz addresses "too close", including a nifty napkin diagram:  http://taperssection.com/index.php?topic=100121.msg1333662#msg1333662

[chris319]

The mics were:

CAD e70, SDC, omni capsule
MXL 991 with capacitor mod, SDC, omni capsule
MXL 991 unmodified, SDC, omni capsule
Studio Projects B-1 - LDC cardioid
Heil Sound PR40 - dynamic cardioid
E-V RE27 - dynamic cardioid
E-V RE55 - dynamic omni
E-V 655C - dynamic omni

One mic at a time, outdoors, waist-height to a standing person, front row on the same level as the ensemble, mono, pointing directly at the ensemble with the diaphragms perpendicular to the ground. As you can hear, I was just a little bit closer to the bass fiddle than to the rest of the strings.

The clip I posted is the Studio Projects B-1

[mfrench]

could it be that you're using tools better suited for near-field, in a diffuse field circumstance?
I don't want to sound like a mic snob, but, none of the mentioned mics stand out to me as being really good in the diffuse field.

[Gutbucket]

could it be that you're using tools better suited for near-field, in a diffuse field circumstance?
I don't want to sound like a mic snob, but, none of the mentioned mics stand out to me as being really good in the diffuse field.

I'm not familiar with those microphones (and haven't listened to the recording sample), but my thoughts are similar.  I suggest trying some mics with more of a diffuse field eq high end boost. If your recording is clean enough to support it you can also eq an appropriate boost after the fact.   Last night I recorded several chamber ensembles and a string quartet from audience height, 15' back (just a couple feet above stage height) with very nice results and plenty of harmonics.. granted that was indoors.  I did dial in about 1db of treble boost when I listened back later at home.

[edited for clarity and miss spelin']

[chris319]

The question is not how to rehabilitate the clip you heard. The question is why eight mics all have HF rolloff. The consensus is that the mics were physically too low and being outdoors, there was nothing to reflect the harmonics.

I suggest trying some mics with more of a diffuse field eq high end boost.

Look at the freq resp curve for the Heil PR40, one of the mics on the list. If that doesn't have HF boost I don't know what does. The PR40 was actually the most promising sounding of the bunch.

[mfrench]

I'll call malarky on being too low.
I can't recall all the times I've blown off concensus with very satisfying results.
One of my last recordings of a chamber orchestra  that I record (from last years seasons last performance), had my main pair at ~3'; also with a spaced omni pair taped to the side of a pair stage monitors less than 6" off the stage floor (monitors were muted - acoustic performance). They were spaced 5' and ~6" high off the stage floor (maybe 4"?), and set up as an experiment (control and test recordings). Great results, both pair.

[Gutbucket]

The consensus is that the mics were physically too low and being outdoors, there was nothing to reflect the harmonics.

I really doubt that those harmonics are being significantly reinforced by reflections indoors, most of the airy top is going to be dissipated before it even gets to a ceiling or wall boundary and then absorbed once it does.  The reflections off those boundaries will pretty much contain all frequencies except the topmost. 

I regularly record classical quartet type music with mics in the first audience row at or just above stage height.  The mics I most often use are sdc condensers with about a 3db boost up top that extends from somewhere below 7khz to above 20khz.  I may dial in a few more db at times to taste.

I also record plenty of fiddle heavy bluegrass and americana music outdoors from instrument height or below and it's not the top end that goes missing compared to indoors, it's the midrange and bass range early reflections and ambience.

I suggest trying some mics with more of a diffuse field eq high end boost.

Look at the freq resp curve for the Heil PR40, one of the mics on the list. If that doesn't have HF boost I don't know what does. The PR40 was actually the most promising sounding of the bunch.

 

Go where your ears are pointing you.  Try out some small diaphragm condensers with a top end rise if you can.  My experience is with Mike on the height thing being marlarky.