Adapting a studio mic for field use

[Alastair Traill]

I have an interest in recording ambient sounds, (nocturnal animals in particular), in very quiet bush settings. This sounds simple but it is not as it is usually very difficult to get close to the sound source. Also the noise generated by any wind as it passes through vegetaion etc is very troublesome. Calm conditions are essential.

For a start I tried a Sony PCM-D50 however the inherent noise of this device at a gain setting above 4.5 on gain scale that went to 10 made it unsuitable for this purpose. The problem seems to occur in all recorders in this price range.

Next I tried a Sound Devices 702 teamed with a Rode NTG-3. This was a considerable improvement over the Sony but the self-noise of the NTG-3 was very obvious at higher gain levels. Sound Devices suggested a microphone with lower self-noise. After a lengthy internet search I finally chose a Rode NT1-A.

This was a big step in the right direction, even though it is classed as a studio mic I was assured it could be adapted to field use. I have a versatile mechanical workshop and I have spent some time trying various adaptations. Initially I tried hand holding it in the supplied mount but soon found the handling noise was very obvious. Next I fitted it to a Rode blimp, again the handling noise was very obvious and I also found that using a side entry mic in the blimp was very uncomfortable.

I then tried a larger home made blimp in which I could use longer “O” rings than could be fitted to the Rode blimp - again the same problem with handling noise. The current version is made a bit like a puppeteer’s marionette with the mic suspended on “O” rings from a handle that I can use to control tilt up or tilt down. It is also easy to suspend from a tree. Handling noise at full gain was initially a problem but I finally discovered that it is not the length of “O” rings that is important but the number of “O” rings in the chain. I have found that if I connect “O” rings to one another using plastic connectors the handling noise drops appreciably with each interconnection, i.e. it is the impedance mis-match that is important. So after a bit of evolution as distinct from “intelligent design” I can now run my NT1-A and SD702 at full gain (if conditions are quiet enough). With it I can hear noises that I cannot hear otherwise. I once inadvertently directed it towards my body and was amazed at the noises emanating from my gut.

The design is not ideal as it does not take much wind can generate noise in “O” ring suspension but as noted above I chose calm weather conditions. However the design is more compact than the conventional blimp design and that makes storage easier.

A potential problem with the NT-1A and other studio type mics is the effect of humidity on the diaphragm. Although I have not noticed any adverse effects of humidity I made provision to store the mic with silica gel. The red container in the photograph contains silica gel behind a perforated screen. The container can be screwed to the mount where it covers the mic capsule. When the mic is in use the red canister is removed and sealed by a screwed plug. Periodically I heat the silica gel to remove absorbed moisture.


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[Andy Balla]

Interesting DIY solution! Without seeing this setup in use, it seems like the mic would swing around a lot when you move it. I'm guessing that once you have it set up, there's not much movement involved.

[Alastair Traill]

Hi Andy,

Is there a commercial solution?

As mentioned I tried both the Rode Blimp and the supplied Rode NT1-A mount but the handling noise was terrible at high gain. The Rode products are well-made and I assumed that they were not much different from other products designed to do the same job. The problem was that I was asking for too much.

In practice the swaying is not a problem as I have to be as quiet as possible and this means keeping as still as possible.

[David W. Jones]

So you picked a large diaphragm studio condenser mic over a high quality field mic because?

[Vincent Oliver]

I think you would have been better off looking at other shotgun mikes, together with a good windshield from Rycote or TheWindcutter.com. The NT1a is a fine mike, but not totally suitable for outdoor use.

I agree with the PCM50, it is so sensitive to the slightest breeze that makes it impossible to produce a decent recording outdoors or handheld use.

[Andy Balla]

I guess the real question is "Are you getting the results you want?" from this setup, and "Does it work for you?". If those are both yes, then it seems you've got it sorted out. BTW, I'm not aware of a mounting system like this from any manufacturer, but it seems to be a pretty niche market kind of thing...

[Alastair Traill]

Originally Posted by David W. Jones

So you picked a large diaphragm studio condenser mic over a high quality field mic because?

Hi David,
I was disappointed with Rode NTG-3 at high gains and as a result I contacted Sound Devices and their advice was to select a mic with low self noise if I wanted to use high gains. I think it was good advice. The NT1-A has low self-noise and the price is favourable.
I did ask about the differences between field and studio mics on this forum and the feedback was that the studio mic could be troubled by both wind and humidity. I avoid the former by selecting windless conditions ( the noise generated by wind as it passes through vegetation interferes with what I am trying to record). So far humidity does not seem to be a problem but I have my screw-on canister of silica gel to deal with the problem.

[Alastair Traill]

Originally Posted by Vincent Oliver

I think you would have been better off looking at other shotgun mikes, together with a good windshield from Rycote or TheWindcutter.com. The NT1a is a fine mike, but not totally suitable for outdoor use.


Hi Vincent,
As I understand it the aim of the shot gun mike is to cut down on sounds (using interference techniques) to the sides and behind the recordist. In the very quiet windless conditions that I am referring to there is practically nothing to cut out so there is no inherent advantage in the shot-gun mic, in fact, there may be disadvantages as I do not necessarily know where the next sound is coming from. Also if there is no wind I do not have a great need for a top wind-shield.


QUOTE = Vincent Oliver,I agree with the PCM50, it is so sensitive to the slightest breeze that makes it impossible to produce a decent recording outdoors or handheld use.

My major gripe with the PCM-D50 is that the “floor-level” noise becomes very noticeable when conditions are quiet at when one is using gains above 4.5 out on a scale that reaches to 10. I get the impression that it is a problem for recorders in this price range and not restricted to the Sony.

I agree the PCM-D50 is super sensitive to wind.
__

[Alastair Traill]

Originally Posted by Andy Balla

I guess the real question is "Are you getting the results you want?" from this setup, and "Does it work for you?". If those are both yes, then it seems you've got it sorted out. BTW, I'm not aware of a mounting system like this from any manufacturer, but it seems to be a pretty niche market kind of thing...

Hi Andy,

I am certainly getting much better results with the 702 and NT1-A combination than with the 702 and the NTG-3 and much much better than with the PCM-D50. So I think I can say it does work for me. I can add that I have stopped looking for something better.

For me the biggest issue to overcome, and the reason I started this thread, was the problem of the handling noise. Another problem was the interpretation of the mic manufacturer’s specifications. Some do not give the specification's you want and there are different ways of expressing the same thing and that made meaningful comparisons difficult..

[David W. Jones]

Something along the lines of an MKH60 into your 702 would be a huge step up the food chain.