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Re: Re: Son of Cheap stereo, uh, bit less cheap.

Subject: Re: Re: Son of Cheap stereo, uh, bit less cheap.
From: Walter Knapp <>
Date: Sun, 06 Apr 2003 03:11:46 -0500
Marty Michener wrote:
> At 03:55 PM 4/5/2003 +0000, you wrote:
>
>>As per Walters Advice I tested the Radio Shack stereo microphones
>>under a pillow to find the self noise. Here are the results.
>>
>>http://www.akwebb.com/gkweather/ambient/selfnoise.html
>>
>>Comments and observations would be appreciated.
>>
>>Greg Kunkel

I should note this is not some new idea I thought up. I probably heard
of it as far back as the 50's, when I first tried it just to see what
happened. Back in the days when I was experimenting with things like
designing pulsed sonar in air and other fun sound stuff. In those days
the recorders were the main source of unwanted noise, times have
changed. Simple and it works pretty well. For those of us who have other
uses for our money than building soundproof rooms, Studios, huge mixing
boards, test equipment etc.

> Dear Greg:
>
> Good post and web display.  Looks to me a bit like the RS self-noise
> challenges the incoming sounds at some frequencies, but it is a bit hard =
to
> tell exactly.

I'm not so sure I'd say that. Since the incoming sound was a particular
sound environment and may have lacked a lot of sound at some
frequencies. You'd have to do a bunch of environments to develop a full
pattern. This method gives you a workable handle on the self noise of
your mic, but is not a exact test measurement.

I do like the superimposed graphs, makes it a whole lot easier than
trying to blend two graphs in your mind.

> I have been reading for weeks everyone shooting down shotguns.  I have ke=
pt
> my mouth shut, knowing lots of real recordists just use them and don't
> participate in all the mad-molecular-microphonology.

I will note here that lots of real recordists just use parabolic
microphones too. And don't normally bother with molecular stuff. They
judge their parabolics by what they get in the field. Though that's
apparently wrong, one should consult a expert for permission to record
(snicker)

I personally don't think it's shooting down shotguns, just taking a
realistic look at their limitations for the type of sound recording in
question. After all we certainly have a bunch shooting down parabolics,
so it's only fair we do a real comparison. This started with someone
with some money burning a hole in their pocket. In that situation I like
to have all the info.

   I have recently
> remained uncharacteristically mum when posters have claimed that shotguns=

> do nothing, apparently, whatsoever, that any field recordist might ever
> want. ;^)  They only shut out sound, not pick it up, etc. etc.  And you a=
ll
> know who you are, the post record has been clear. :&0))

It does help to look at the specs and polar plots for what you use.
Sennheiser has them on their website for most of their mics under
discussion. Like those of us who will continue to use parabolics for low
frequency calls that they "don't pick up", there will be those who will
use shotguns for low frequency pickup even though they are not
directional at those frequencies. But it's nice to understand what you
are doing. And if thinking about buying it's real nice to examine the
specs as one aspect of making a decision. At least shotgun mics can use
internal reflections of wavelengths bigger than their size.

> So, Greg, in yet another attempt to silence the "spend it all" crowd,  I=

> have tried to mirror your terrific web page (my compliments!) using my tw=
o
> (not cheap) Sennheiser ME-67s.  Repeatedly, I have assured this group ove=
r
> years that the 67's are more quiet than is ever necessary in any real fie=
ld
> setting for going out and getting a bird's sounds.  Their portability
> through the puckabrush more than makes up for their inability to "gather=

> any sounds".

Around here porting a shotgun mic (or any other kind) through the
puckabraush will likely get you shot or arrested. It's wall to wall no
trespassing signs and owners who will jump you the minute you get out of
the truck. What I can get nearly always must be gotten from the public
right of way, and some owners have taken exception to that. Especially
after 9/11. I envy those who can freely flit through the brush without
fear of jail or buckshot. It's been much less pleasant out recording
this year.

I was actually accosted by a owner who drove his tractor down the road
to where I was recording, making for a very long interruption. To make
sure I was not stealing anything. Both sides of the road were a swamp
for as far as you could see. Only man made objects were the no
trespassing signs. I still wonder if he was worried I was stealing his
swamp.

All of that does have some effect on the equipment packages I use.
Though if anybody has been paying attention they will notice that I
currently own 4 shotgun mics and am using them, even if they are highly
disliked models. As well as mic setups that can only be used close (also
made using highly disliked models). And continuing to use my hunk of
absolute junk Telinga Parabolic (shudder) that picks up nothing at all.

Or maybe I should take up recording terrorists. Our government assures
us there is one under each leaf and twig. And several have joined that
thing drooling under the bed in the darkness. I wonder what the sound of
terrorists slipping through the leaf litter is like. I better find out
what frequency it is. If it's low frequency I'd hate to make the mistake
of recording them with a parabolic. Of course soon we will be hip deep
in homeland security animals as well, even more to record. I bet their
calls resemble elephants. Good thing I have some mics that record
infrasound. Or do they?

The opposite of spend it all is spend too little. There is a balance in
between. Decide what you want to record, make some realistic judgment as
to the sound quality you will be satisfied with, find out what equipment
meets those things and have at it. If you find that matrix is above your
means  you can compromise, just be aware you are doing so. There is no
free lunch.

I'm rebuilding the roof on my house, which was definitely built by the
cheapest is best method of material choice and design. You don't want to
know some of the things about a cheapest is best electrical system
either. Or, you can use less siding boards if you ignore the exposure
width recommendations. We bought our place for the land, I saw all that
before we bought. I'm slowly doing things right, at some cost. Had it
been done right to start with that would have been cheaper. Being cheap
is not a virtue. Though here in Georgia they make it a religion.

> I do NOT use them for studio-quality ambience recordings, and on those
> points I do not argue.  The only real argument has come from one
> participant who, in retrospect, told me he has only used Sennheiser's
> forerunners - the ME-80 series, before the quieter self-noise technology=

> occurred, and never actually heard a ME-66 or 67.

You can use them for a certain size of ambiance soundfield. Not all
choice ambiance is of the wide open, all around kind. Within their
limitations they will do studio quality work.

> Thanks to Walt's suggestion and to your example, I am able to post somewh=
at
> comparable results at:
>
> http://www.enjoybirds.com/howitworks/micCompare.htm
>
> Please note, the "ambient" recording was with no nearby birds singing
> whatever.  Bird song would be on top of the ambient levels.
>
> While far from CHEAP, the ME-67 are far cheepier than the MKH series (USD=
 x
> 3?), and despite dire warnings that you should always upgrade to the very=

> best, (if necessary I suppose cancelling your car, health and house
> insurance to pay for them, or (horrors, learning to cope with ebay), many=

> of us continue to use them to great satisfaction.   I would love a grant =
so
> that I could upgrade, meanwhile there are these results to look at.

I don't believe that's been the message at all. But upgrading to the
best you can reasonably afford seems like a good idea. And what you can
reasonably afford is up to each person to determine. As is determining
what's the best for them. There is no one best for everyone.

Note I don't consider it reasonable to do without regular things for
modern living. This is, even for most who make some money, a hobby.

Or should we just talk about the cheapest walkman MD and a Radio Shack
mic? I personally think we should talk about the full range of
equipment. I enjoy a well recorded bit, no matter what it was recorded with=
.

> BTW: As a point of reference, a sound 6 to 10 dB louder than another soun=
d
> of similar frequency distribution, pretty well drowns it out. 12 to 20 dB=

> is a terrific margin.

This is true if it's a steady difference. So much of what I record has
these pesky moments of silence here and there. Those can be 50dB or more
below the call levels sometimes.

I think that self noise becomes a issue mostly when trying to push a mic
to the limits of it's reach. Then we amplify it's weak pickup,
amplifying the self noise as well. Until it does intrude. Very often the
ultimate limit of reach of the system is when this self noise overwhelms
the signal. Particularly with new people moving into the field from
music, where self noise is virtually ignored are mystified by all this.
Just like we pay little attention to music's important spec, the max SPL
rating.

> Ok, let the torches blast . . . Compared to this winter-reversion we have=

> in NH, the heat may do me some good.

Now climbing into the summer temps, I'm not quite into my summer
uniform, shorts & T-shirt plus field vest, but close, and mostly too hot
for wearing too much. Increasing my salt intake while my Doc pumps me
full of diuretics to dump it back out. As if the sweat was not enough.
That guy is really trying to stop my field mobility.

The spring peepers made homeless by the loss of dry pond swamp have
found our water features. Or at least some of them. They have been out
nearly every evening for weeks, far more than our normal crowd. Sure
wish I had more water to offer them. We also have a surplus of green
frogs showing up. There will be more species as the season progresses.

Maybe I'll ask for a little care package of cool once in a while. Sounds
like you have some to spare.

Walt




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