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![]() by Pat Kirtley |
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My dad told me the story of a recording he made in 1954 of a piano recital given by his sister when she was graduating from music college. It was a special event in a big hall with a full concert-size Steinway grand. His rig was one of the most portable recorders available at the time - a one-channel Magnecorder reel-to-reel tape machine in a two-piece travel case weighing 65 pounds. That was portable recording then - now, we can carry around a miniaturized digital recorder, complete with stereo microphones, in a coat pocket. The entire package weighs less than 10 ounces, and is about the size of the level meter on the 1954 Magnecorder. High quality "pocket recording" is now a reality. The size reduction in portable recording equipment has been an incremental process. For years the smallest battery-operated pro audio recording machine you could get was made by Nagra in Switzerland. It weighed six or seven pounds and cost around $5,000. Electronics companies made valiant efforts to miniaturize and improve portable recorders using the familiar compact cassette format, and brought the size down to impressively small dimensions. But even with Dolby or dbx noise reduction built in, these units failed to deliver pro-level recording quality, except in a few voice-only or sound effects gathering applications. If you wanted portability for master quality music recording, machines like the Nagra remained the only weapon of choice. Miniature DAT I bought my first “pocket DAT” around 1993—a one-pound unit by Denon—and it immediately changed my approach to recording. Freed from the need for an AC power source (the unit had a NiCad battery with more than two hours run time), I could record just about anywhere, as long as there was ample blank tape. The mic preamps in the unit were nothing to get excited about, but weren’t too bad, either. After building adapters to mate the standard mic connectors to the recorder’s 1/8" miniplug inputs, I was ready for action. I took the recorder into environments where I wouldn’t have bothered trying to record before—small clubs to capture an Irish acoustic band, construction sites for environmental sound effects gathering, my own concerts, where I began getting the best “board tapes” ever—and even made casual recordings of my own guitar playing. I realized that the ease of doing it made all the difference. My entire kit of equipment was in a bag weighing a few pounds (though the cost was a few thousand dollars). It also made a difference that I wasn't scaring anyone with formidable-looking gear. How many times do subjects, even professional performers and actors, change their attitude and/or freeze up when a photographer, videographer, or recordist shows up? With my pocket DAT setup, I raised no eyebrows, and even if they knew I was recording, it just didn't look like a rig that would give master-quality results. (Note: I do not make recordings of musical or theatrical performances without explicit permission.) The DAT format is fairly robust, with the tape protected inside a sturdy plastic shell, but it's still tape, and tape with always have the downside of being fragile. DAT tape is thin, and must move accurately across a rapidly spinning head-drum assembly. Anyone who's used DAT for any period of time has seen tapes "eaten" due to wayward transport problems. With portable DAT machines, another nagging problem shows up—moisture. Any moisture or condensation buildup on the head drum assembly causes the tape to bind and snarl, and when transports are moved from a cold environment to a warm one, condensation can easily occur inside the machine. Many DAT machines have internal moisture sensors that will shut down the machine if condensation occurs, but they you could find yourself without a recorder at a critical time. Then Came
MiniDisc While DAT takes criticism for potential mechanical and tape problems, the mechanically stable MD format has been called into question for audio quality issues, regarding its use of data compression. The MD data compression system, known as ATRAC, is probably the most sophisticated audio data compression technique ever created. It compresses digital audio data at a 5:1 ratio, meaning that about 80 percent of the original data is thrown out. It would seem impossible to preserve audio quality with that much missing, but actually the data isn't thrown out—it's recoded by a special computer processor into a much more compact form. As another real-life example, data compression is used in digital cameras, too, and in that application they get away with using huge compression ratios of up to 25:1 but the loss is barely perceptible in the resulting images. The ATRAC system yields recordings that sound equivalent to DAT or CD quality in almost every way, and few discerning listeners—in double-blind listening tests—can tell the difference. MiniDisc
Portables Beyond sheer portability, MD has a strong advantage in portable recording that comes from the inherent random-access nature of digital disc recording. With tape machines, before making a new recording on a tape you've already used, you have to make sure that you are at the end of the old recorded material, or you will obliterate it with the new material. In most MD machines, this process has been made completely foolproof—when you press record, a new track is automatically created and that's where the new recording goes. (Most manufacturers' designs work this way, but ironically, Sony, inventor of the MD format, persists with including an "end search" button that you must press when making a new recording on a previously used disc.) Mics and
Plug-In Power Most truly miniature high-quailty mics are going to be of the electret condenser variety. Why? because these are the designs that can be shrunk to the smallest dimensions. Standard condenser mics need a considerable amount of internal electronics to create a polarizing voltage for the element, and circuitry to match the high impedance of the capsule with the input electronics of consoles and recorders. Electret condenser mics need no polarizing voltage, and just a couple of volts to run an internal buffer amplifier. Many portable recording nits, both DAT and MiniDisc, supply this "bias" voltage via a feature called plug-in power. It is a standardized system, with specifications agreed upon by both the recorder and microphone manufacturers. Here is the spec: The microphone connector will be a 1/8" stereo (tip-ring-sleeve) mini-jack , and the machine will supply approximately 1.5 volts DC to that input. Most machines won't like it if you try to use microphones that don't conform to the specification (e.g., older miniature electret condenser mics that have their own self-contained battery power sources, or standard dynamic mics). The good news is that there are numerous affordably priced plug-in power mics that will yield excellent results with the new recorder designs. On higher end DAT and MD recorders, you will often find quality built-in mic preamps with standard XLR microphone connectors, which can directly accept a wide range of microphones. These are not exactly "pocket" machines, though, and are the size of a medium hard-cover book with a weight of around three to four pounds. The minuscule dimensions of pocket recorders rules out using rugged XLR connectors, and we must learn to live with relatively fragile 1/8" jacks if we want pocket portability. The Right
Microphone Several small specialty companies have developed miniature stereo microphones designed specifically for live recording with miniature DAT/MD machines. In general, their designs are based on miniature microphone modules form sources like Audio-Technica and Panasonic. The best of these mics are excellent, and the companies have created many special-purpose mics as well as general purpose stereo pairs. One of the most crafty and useful designs is the "T"-style microphone from Sound Professionals. This ingenious little stereo mic is about the size of a drum-tuning key, and fits directly into the mic jack on a portable recorder, with no cable at all. The recorder/mic combination becomes a one-piece handheld "soundgrabber," unencumbered by cables. For about $50, this mic is great for general recording and excels at lecture/interview applications. At the other end of the micro-mic price range is the DSM series from Sonic Studios. These mics feature a pair of miniature premium omni mic capsules adaptable to a number of interesting configurations. The applications include attachment to the earpieces of a user's sunglasses, and attachment to an available dummy-head for binaural/stereo perspective recording. These mics have gotten rave reviews for their performance in acoustic concert and classical music settings. In the middle range are versatile mics like the Sound Professionals SP-CMC4 Premium Cardiods, a set of two matched miniature units based on the Audio-Technica AT-853 capsule. These microphones are available with integral miniature clips that allow them to be used in many different ways, and boat impressive specs (frequency response of 30-20kHz and a signal-to-noise ratio of 67 dB). High SPL
Options and Filters Pocket Recording
Communities DAT fans congregate at a site called DAT-Heads (www.eklektix.com/dat-heads), and MiniDisc proponents find tons of information at sites like The MiniDisc Community (http://www.mini-disc.org/) and The MiniDiscussions Page (http://www.minidiscussion.com/). Besides publishing lots of equipment reviews and opinions, they feature focused, topical mailing lists and discussion groups where you can air your views and seek advice from others. Get Out
There and Record
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Copyright © 2000 Cherry Lane Magazines |
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