Azden’s Versatile New Shotgun: SGM-250
Azden is taking a major step forward in its shotgun microphone design, with the SGM-250. The sixty-plus-year-old Japanese company has studied the market’s offerings and come out with a totally revamped, dual-powered shotgun specifically designed to compete with others at its moderate price point. Made in Japan and targeted at audio professionals in the video production industry from Broadcasters to DSLR users, the ground up redesign includes a new microphone element that is more durable and lighter in weight, for improved transient response and detail. The element has a wide frequency response of 20-20,000 kHz, and can withstand high sound pressure levels without breakup and distortion. The microphone barrel is also a new design. Rather than stamped aluminum, which is common in this price range, the barrel is a metal alloy with a combination of magnesium, copper, silicon, zinc and aluminum, resulting in improved strength and damping. The inert nature of this alloy does much to defeat the “ring” aluminum can cause, and adds little to the overall sound of the microphone. It makes good sense if a company is going to put a lot into the element, they should make sure the barrel doesn’t change its sound.
The SGM-250 runs on 48V phantom power or a single AA battery. Azden has managed to ensure that the performance is very similar, running on either power source. Battery life with a standard alkaline is 100 hours. The battery LED will start flashing when about 10 usable hours of battery life remains. The microphone also features a newly designed low-cut filter. Most shotgun microphones, by design, have a tendency to emphasize bass frequencies, which can make voices sound a little unnatural. Many low cut filters have a sharp roll-off, and this tends to make things sound a little thin and weak in the bass frequencies. The SGM-250’s filter rolls off more gradually, so when engaged, voices retain a more natural sound. The switches are recessed to avoid accidental movement, and there’s even a Battery / 48V switch that saves you the trouble of removing the battery when not in use. Other features include a gold-plated XLR connector, shockmount holder, foam windshield, and zippered leatherette carrying case. The SGM-250 comes with a two-year parts and labor warranty that can be upgraded to 10 years simply by registering the product at the company’s website.
To test the SGM-250 in my studio, I plugged the microphone directly into a MOTU Traveler interface running on 48V phantom power and addressed it directly into the front as I would to record a voice-over, and I found it to sound articulate with a nice full, but not hyped, proximity effect as I got closer. I could not hear any difference, whether running on 48V phantom or internal battery power. However, when I ran a white-noise test with the mic, I could see the level was approximately 1 db lower when drawing AA battery power. That’s a negligible amount that would make little difference when trying to get the signal to sit above the noise level of a given recording device. This is great news for DSLR / Mirrorless camera users with no XLR inputs.
With the knowledge that the microphone sounds the same running on battery power, I mounted it on my Panasonic GH4 camera using the included shockmount, and went for a little walk around the neighborhood. I was handholding the camera and found the shockmount subdued most of the handling noise. I recorded my dog walking around, kids playing in the street, passing cars, people mowing lawns, and some adults talking and laughing, along with me narrating my settings and what was happening. I first set the GH4 to the lowest audio setting, which is -12 db, and found it was a tad too quiet for my taste, so I moved the level up to -6 db and found that to be a decent recording level without the camera’s preamps introducing audible noise, except in the quietest environments. At 0 db on the camera, I could hear a very slight hiss that isn’t really noticeable until you try to turn up the level in post, and with the GH4’s audio all the way up at +6 db, there was a definite hiss I would not want to deal with later. Of course, this noise was coming from the camera’s preamps, not the SGM-250.
What is important here is that the SGM-250’s sensitivity, -38 dB at 1 kHz (0dB = 1V/Pa), is good enough to get clean audio, plugged directly into my GH4. Listening, back in my studio, I could hear the gentle crush of the grass as my dog walked around and sniffed things. It sounded natural, as opposed to brittle and tinny. As I spoke into the mic, my voice cut through the background noise of the neighborhood clearly, sounding full-bodied and professional. The voices of the children playing across the street were clear from 40 yards, even with cars running 90º off-axis from the mic. The industrial hum of a workshop’s compressor came on, with a low rumble I didn’t like, so I engaged the low cut filter, which got rid of a lot of the unwanted low-frequency noise. I like not having to use a small tool to engage the filter. The switch is sturdy, but did not require a lot of pressure to slide. When it came to recording my own voice, I did notice less bass response, though the overall sound was still usable and natural without being overly trebly.
In my kitchen, I stopped to speak with the microphone approximately 12-18" away from my mouth, with my refrigerator about four feet behind me. It sounded as expected, like a guy talking with a refrigerator running, but what struck me was how much less background noise I heard when I rotated the mic 90º. This shotgun is doing its job! I moved into my bedroom, where a small boom box was playing, and the music sounded full and uncolored. I turned the microphone 90º off-axis and the music’s volume was much lower. Turning 180º from the source, the level was not quite as low, and there was more bass response than when at 90º off-axis. I decided to check the off-axis rejection back in my studio, with another white-noise test. First I blasted white noise into the front of the microphone to get a control level, and then I rotated the mic 90º and found that the level had dropped a full 9.8 db, and a respectable 7.8 db at 180º. I noticed the vertical slots on the shotgun’s interference tube are very tightly spaced and precision-cut, which, I’m sure, enhances the excellent rejection characteristics to the sides and rear.
Next, I tested the SGM-250 running through my Sennheiser G3 wireless system, using the plug-on transmitter to send the signal to the receiver, which was wired directly into the camera. The shotgun sounded the same through the wireless as when plugged in directly, though I was unable to securely screw on the transmitter in the same way as my handheld mic. In all fairness, I can’t attach the plug-on transmitter securely to any of my shotguns. If you plan on using the mic this way, use some gaffer tape to make sure the transmitter doesn’t dislodge during use. Using the mic handheld, interview style, I engaged the low cut to defeat handling noise and was happy my voice did not sound thin. It was clear and full, with the added richness of proximity, because I had the mic 5" from my mouth.
For the next test, the microphone was drawing battery power and plugged directly into my Sony D-50 portable digital recorder. This recording method acquired the best results so far, with no noise and better overall sound, which would be expected, compared to the camera’s preamps. This setup would be professional enough for most people, but who wants to be most people? You never know what might jump out at you volume-wise, and using a professional preamp gives you the best signal-to-noise ratio.
Then, I powered the SGM-250 with 48V from my Sound Devices MixPre-D, and ran the signal into the Sony recorder. I found that to be the best-sounding recording of all the tests. Also important to note is that the MixPre-D has optical limiters, which will save your recording from unexpected volume spikes much more readily than digital limiting in recorders or cameras, and with a more natural sound. I removed the external recorder from the setup and connected the output of the MixPre-D directly to the GH4, with the camera’s audio set all the way down, and found the sound to be very similar to the D-50 and very usable, though for serious work I would stick with the external recorder.
Overall, I would say the SGM-250 performed beautifully in all of my tests. The big takeaway for me is that I can use the microphone running on a single AA battery and the most basic setup, and still get clean, full, and articulate audio with great off-axis rejection, at a price that is very reasonable.
|Mic. Element||Electret Condenser|
|Frequency Response||20 Hz – 20k Hz|
|Low-Cut Filter||Selectable @160 Hz, 3 dB/Oct|
|Dynamic Range||115 dB 48V phantom / 110 dB battery|
|Sensitivity||-38 dB at 1k Hz (0dB = 1V/Pa)|
|Impedance||120Ω (at 1 kHz)|
|Max. Input SPL||132 dB 48V phantom / 127 dB battery (1 kHz at 1% T.H.D.)|
|S/N Ratio||77 dB (1 kHz at 1 Pa)|
|Self-Noise||17 db A weighted|
|Power Requirement||11-52V Phantom or AA battery|
|Dimensions||250 x 21mm (9.84 x 0.83”) (Length x Diameter)|
|Weight||5.65 oz (160 g)|
|Accessories||Shockmount, windscreen, carrying case|