The Holophone PortaMic 5.1
Now that 5.1 and even 7.1 surround sound tracks have become the norm for movies and many other kinds of programming on DVD, gathering authentic ambient audio to complement the primary "action audio" has become increasingly important. The ideal way to do this would be multiple microphone recordings on location (or at least one separate ambient audio recording to complement the primary audio captured concurrently with the video). However, in today's budget-driven media environment, the shooter must do double duty as soundperson and hence must try and capture as much ambient audio as possible while shooting on location.
While this is a challenge, it is not "mission impossible," especially with some of today's new tools. One of these is the surround sound microphone. While such mics been around for years, only Holophone has made them camera mountable, and that company's PortaMic Pro is their latest, most compact and portable version yet.
The compact PortaMic Pro resembles a goose egg on steroids with a short stand. It measures about 3x4.5-inches in diameter, with a taper to a blunt point on the front end. The mic head incorporates six distinct mic elements configured much like the standard 5.1 speaker setup in a studio or home theater.
Each of these mic elements is protected by a large rubber washer, giving them a ship's porthole appearance. Actually, the mic head as a whole looks much like a very compact research sub ringed with portholes. Its slate-black finish appears to be a hardened polymer.
Its base measures 4x3x2-inches aside from the hotshoe post. Switches and inputs are well spaced on three sides to provide easy access and to avoid confusion. The function switches include power, a 12 db pad, and zoom, all of which have corresponding LEDs that glow either green or red, with the later color flagging a problem. The mic also has LED indicators for the left and right channels. These glow green when the unit is getting an adequate signal, and change to red when it's being overloaded. The microphone gain level can be adjusted via a knob that protrudes through the housing just enough for easy use.
There's also a 12 VDC input, a mini-plug unbalanced stereo output, and a 6-pin, mini-XLR balanced stereo output. The microphone is phantom powered by a standard 9 Volt battery.
The PortaMic Pro is designed for professional point-and-shoot use with standalone audio recorders, camcorders or with HDSLR cameras. It's also equipped with a Dolby Pro Logic II encoder that allows the unit's six audio channels to be encoded to two channels for recording on any stereo recording device.
One of the PortaMic Pro's distinctive features is its audio zoom control. This is a simple on/off push button that, when activated, adds a forward bias to the mic's pickup pattern, thus decreasing pickup from the rear. The resulting coverage pattern then more closely resembles that produced by a cardioid mic than that from an omnidirectional mic.
The 12 dB pad is a really useful function for a microphone with such a broad standard pickup pattern. This attenuator reduces pickup to 1/16th of normal, thus dampening the sound levels encountered at sporting events, parades, and on traffic-congested streets, preventing the recording device from being overdriven.
I had previously tested Holophone's H4 SuperMini, which has a somewhat top-heavy and vertical profile, and was impressed with the PortaMic Pro's low profile and compactness. These features make it much more user-friendly, especially when used with smaller cameras.
The 9 Volt battery provided with the mic was difficult to install. The cavity is just large enough to contain the battery, and some amount of effort was required to make everything fit together. However, this is really a small tradeoff when given the mic's compactness and portability. Once loaded, the PortaMic Pro's green LEDs lit up and then extinguished, as soon I pushed the power switch (which is quite flat to prevent accidentally moving it).
Before starting my shoot, I slipped on the supplied foam windscreen, which is secured somewhat loosely by two pairs of Velcro straps. For good measure I also added the optional Rycote windjammer sent with the microphone. This slipped over the windscreen snugly, ensuring that neither would fly off accidentally.
Initially, I mounted the unit on the hotshoe of a Canon XL H1, plugged in the pair of male XLRs, and was ready to roll. My first test was behind some buildings along a busy road. The PortaMic Pro and I were about 100 feet from the road and I was standing with my back towards it. Nevertheless, the mic picked up the rumble of each passing big truck as if I were facing the road. It was interesting to hear the truck's rumble being reproduced in the headphones and moving from right to left as it roared past. In front, I picked up a range of bird calls, the soft coos of doves, the harsh caws of crows, the chattering of sparrows and the clear whistles of cardinals. Each was captured clearly, as if on a separate channel instead of being mixed down to a stereo pair. The differences in pitch and tone were even more distinct and had better separation when heard through my surround system—especially the rumbles of the big trucks and an occasional backfire from one of them.
I noticed similar results when I recorded the second largest U.S. St. Patrick's Day parade held in Buffalo, NY. As I recorded, I experimented with the options the mic provides: with and without zoom, and at various audio input level settings. What impressed me most was that regardless of the gain level used, I was pleased with the clean quality of the audio in almost every case—especially when I brought in the 12 dB pad. I used it more than half of the time due to the many bursts of harsh, and often very loud, sound from blaring sirens, honking horns, noisemakers, and the crowds of people shouting, cheering, clapping and talking all around me.
With a mono shotgun mic, or even with a stereo one to some extent, what typically gets recorded is predominant foreground sound along with various background sounds that often blend together, especially when capturing in mono. However, with the PortaMic Pro, the individual sounds in this cacophony retained their distinctness and directionality in many cases, just as you might directly experience in a crowd situation. In fact, that was my overall impression during playback; it sounded very much like being there when played back through my surround system. The bass sounds were most impressive.
I did overmodulate a few times (without the 12 dB pad) when audio gain was set fairly high, and especially when several or more revelers were shouting close to the PortaMic Pro. However the audio track was salvageable in nearly all cases when the pad was used. I was equally surprised at the quality of dance music that I recorded from mobile stages with their stomping "River Dancers." In most all situations, the PortaMic enabled me to capture the rich tapestry of parade sounds while preserving their flavor, quality and separation from all of the other sounds swirling about the camera and microphone. I was equally impressed with the minimum of camera handling noise that was recorded, although under the circumstances, this was small change. My only real complaint was that I routinely got my trigger finger caught in the six-foot audio cable wrapped around the hotshoe post and missed part of a shot.
If you want to capture the audio tapestry of a scene very realistically in a three-dimensional manner (much as your ears experience it), Holophone's PortaMic Pro is really a great tool. I found that recording with it was fairly easy and effective, aside from a few minor snags. With very few exceptions, the results exceeded my expectations. This microphone has an important role to play in capturing rich audio for 5.1 mixes. However, as with all such tools, it needs to be used with care to avoid capturing more than you intended.
Carl Mrozek operates Eagle Eye Media, based in Buffalo, N.Y., which specializes in wildlife and outdoor subjects. His work regularly appears on the Discovery Channel, The Weather Channel, CBS, PBS and other networks. Contact him at firstname.lastname@example.org.