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Re: Re: testing,.. surround

Subject: Re: Re: testing,.. surround
From: Walter Knapp <>
Date: Sun, 01 Jun 2003 14:07:05 -0400
Rob Danielson wrote:

> So where's the dreaded phase cancellation?  Out of curiosity this 
> afternoon I used a VST plug called "round panner" to place (mix) six 
> channels randomly within a 5.1 speaker arrangement. Over 15 minutes, 
> I heard a very minor phase dip or two and a couple of unnatural slap 
> back echoes. A sense of unified space was always maintained. Perhaps 
> phase cancellation depends on precise alignments and uniform 
> surfaces, which the landscape doesn't provide?  The limestone wall 
> could be acting a little like the rim of an ear --  adding useful 
> complexity while reflecting.  There is some parabolic focusing as 
> when a distant owl is picked up only on one mic and gurgling from the 
> river that is unexplainably up front. At times there is too much 
> going on for me, but its refreshing to be able place some mics a 
> further away from hot spots and use the air.

I think the reason for this may be that the natural environment creates 
such a mix of phase and reflection shifts that no single one stands out. 
In the much simplified indoor environment a single shift will be much 
more evident.

In which case we need to investigate if the 3:1 rule and other rules 
that are about phase and reflection problems apply in nature recording. 
Or to what extent. Develop our own rules. Lots of experiments needed.

>>And then there is the problem of practical, battery operated portable
>>multichannel recorders.
> sans the car battery and long runs of wire:

Unfortunately, the car battery and runs of wire are part of the 
practical problem. A notebook computer may be ok for such a multichannel 
array, which because of the effort to set it up is not portable. In my 
approach I want to be able to carry a full recording setup on me. Though 
at times I may use supports and so on.

If I try to go into a site, it's extremely rare there is so much as a 
trail, it's through the brush. And that the footing contains water and 
soft mud and such like does not help. And the carrying of the gear 
cannot distract enough to where I don't see the snake...

This approach is really why I don't see a laptop as a practical solution 
except in fixed locations. Having it running while moving would be very 
unsafe for both me and it. Whatever I use over the years, it's going to 
be a recorder designed specifically for the field. For recording while 

> It started me thinking more about the Sound Devices 744,...two mic 
> preamps, 4 channels and fits in the palm of a hand. Add an MP-2, 
> battery pack and it would be much smaller than my current stereo rig. 
> While working with the files on the laptop, I discovered I was making 
> global EQ settings, regions, exporting sub files, logging and burning 
> to DVD-R all at the same time.

Yes, there are some solutions. But in the setup you had you were still 
not mobile enough to follow animals that were moving while calling. And 
it took some time to set up. Even changing your location a little bit 
would be difficult.

Even if working quality recording I cover a number of sites in a few 
hours. If doing survey I may travel 50 miles or more in a evening 
stringing sites together. That puts certain limitations on speed of 
setup and takedown. I can easily be recording within a minute of 
arriving at a site, and leave just as rapidly. Though I usually take 
longer. Even doing the samples from all those different mic setups can 
be done rapidly in my system, depending on how far I'm walking.

I'm not sure you'd need a MP-2 with the new Sound Devices recorder. I'd 
expect that they have built that pre in.

> The line between equalizing and mixing is one I'd like to cross less 
> often. Single field recordings standing on it their own-- Aaron Ximm 
> has great talent for this.  When a recording seems to have promise, I 
> enjoy attenuating the dominant frequencies that are masking 
> attentions to other frequencies and textures.  Each file brings a 
> complex of issues to resolve. When I have to mix files to create 
> something that is missing its a lot of work to do right and not as 
> much fun. Recording six channels at once using only what's there has 
> some of both methods.

I'm also not too interested in mixing. Though I'm comfortable in 
filtering as necessary. So, I'm not a total purist.

> One good trick you probably know of, but others may not: Gradually 
> increase the playback volume from "off"  making note of the tones and 
> textures your ears first detect. If you push these back with careful 
> EQ attenuation, more space opens.  Even cutting back dominant, 
> sustained notes in animal calls can make the overall recording more 
> tonally balanced and the call more informative.

I'm aware of this technique. But don't use it a lot. I am primarily 
working on techniques of getting the raw material at this point, ie the 
original recording.

I tend to record during the season, then in the off season process the 

The heaviest batch of processing I've done recently was for the Georgia 
frog CD. And there most of the months were devoted to coming up with 
clear, and accurate ID clips. The chorus material was filtered very little.

> I really should get that stereo book.  I am working the Field Mic 
> List. Soon, I'll be asking some folks to provide comments about their 
> favorite mics/techniques. Rob D.

That book is pretty good to keep on track with various techniques. It 
also goes into a lot about how we hear sound in the course of explaining 
various techniques. It does have a section on multimic and on surround. 
You may be familiar with a lot more than most would be of the techniques 
it goes into. For anyone thinking about a heavy commitment to move into 
stereo it's a valuable book.

One other thought on large array recording. With the continually 
increasing noise problem I expect that directional mics will be more and 
more necessary. Open arrays recording from all directions are going to 
be special occasion things. Or, like in science recording, where we can 
tolerate picking up more noise. For this reason alone I'm not all that 
hopeful of surround recordings ever being a big part of nature 
recording. Even if all the equipment problems are solved. I'm focusing 
on stereo, which is bad enough for the noise problem.



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