|From Studio to Field|
(and never back again')
There are three, common raps against taking large diaphragm condenser mics out into the elements: 1) The greater mass of the diaphragm pervents it from responding quickly enough to the "transient" qualities of natural sounds. (2) The more "treble-centric" nature of their polar patterns will make sounds from the sides and rear seem overly dull and (3) The mic capsules will start "sputtering" and eventually stop working in high humidity.
Before 2004, sound recordiists with a passion for ambience and other subtle sounds had to spend $1800 or more for a pair of small diaphragm mics with very self-noise and high output. (Most often, Sennheiser models MKH 20, 30, 40, 60, 70, 80 and 800). Then Rode, an Australian microphone maker, introduced the NT1-A-- a large diaphragm mic, with high output and incredibly low self noise-- a full 4dB lower than that of the quietest mics then available. It was predictable at that point that some fool was going to risk $400 for a pair and try them out in the woods.
I set them up with long cables along the rim of the Little Missouri River Valley In North Dakota at dusk . I plugged the cables into a Sound Devices MP-2 and the mic preamp into my Macintosh laptop. When I cranked up the gain, I heard soft popping sounds that I could not trace to bad cables or connections. I walked over to one of the mics and realized that the minscule sounds were coming from the tree leaves surrounding the mics. (They looked to be in the cottonwood famiy. I assume cooling down after a day in the hot sun) I had never been able to hear events of this scale with other mics. Allan Haighton, an early NT1-A experimenter writes, "I now use little else for open mic recording. They've completely seduced me..."
Since Summer 2004, I've monitored hours of NT1-A recordings and I've not yet noticed a moment that I could point to as poor transient response. I have noticed that the polar patterms are distinctly "brighter" in the middle than other cardiod mics, but the result can be extraordinary detail over 120 degrees of coverage for a stereo pair. For ambience, lower register frequency response is critical and the mic's "wide cardiod" pattern expands to about 270 degrees at these frequencies. I've kept a pair on my 4 channel surround rig for over two years now simply because I cannot find (and afford) anything better. (I'd trade them in for 2 mkh-80's or 800's if anyone os interested!)
The NT1-A's have some drawbacks, but vulnerability to high humidity has not turned out to be a major concern. One pair I purchased in Fall of 2004 (serial numbers 7734 and 6784) did begin sputttering after 6 hours in 100% humidity, but I sent them back and they were replaced with units (serial numbered ciirca #21283) that did not have these problems. I'd rate their performance in high humidty as comparable to that of my Sennheiser mkh30/40 pair based on sie by use in wetlands and forests from Louisiana to Canada over over the last two years.
My NT1-A's are not as responsive between 250 and 40 Hz as my Sennheisers, MBHO's or AT-3032's. I've learned to appreciate this as much as they still present me with plenty of low-end content to work with. They have a pronounced boost in bass response under 30Hz which comes in handy for the LFE content in surround work. I understand that mic sensitvity is usually measured for specs at 1000Hz, but based on the output of other mics with 25mV/Pa sensitivity, the NT1A's would not rate this high. When I look at my reponse cruves in Firium, its hard to not suspect that a good part of their effective output is below 30Hz. I usualy have to boost the signals from the NT1-A's about 8dB in post to match the outout of the MKH-40.
Eric Benjamin of the micbuilders list has done extensive testing of the NT1-A's in his lab and has found their self noise performance to meet Rode's claim. This test with his 1/3 octave polar pattern test are linked on this page. Through mixing and equalizing recordings made with NT1-A's, I've learn to recognize that their frequency response from 4K to 8.5K is on the "grainy" side. (Incidentally, this is less the case with the NT2-A and I'm curious to try a pair of the NT2000's to see they are a further improvment.) What I hear are very narrow bands of exaggeration between 3.7-9K that can be painstakenly attenuated with a narrow bands of parametric equalization such as a audio plug like Eqium. All condesner mics I've used exhibit some narrow peaking in the high registers; its a little more pronounced with the NT1-A and it can be tamed in post.
I will try and add to this section on the NT1-A's as reports come to me. Check the links for pictures of the rigs people have made, sound samples and my "Shoe Goo" capsule modification which allows the NT1-A to be used like a traditional, horizontal. front-facing mic. -Rob Danielson