Hack69.Assemble a Small Recording Rig

Hack 69. Assemble a Small Recording Rig

Podcasting on the road opens up a whole new realm of interesting and engaging content. Learn how to build a small audio rig that will give you sound that sounds as good on the road as it does at home.

To get quality field recordings you need to start by getting a good recording device that fits into your budget. Next you need to put the right microphone [Hack #13] on it and understand a little about how to use it. I'll walk you through these steps, and then I'll give you a few tips at the end of the hack.

This hack is not just about field recording, though. Solid-state recorders, such as the Marantz and the Edirol, can do a better job at recording than a computer with hardware at the same price point. Plus they have the advantage of being portable, so you can take them anywhere. They are dedicated to the task, so you never get glitches or missing samples, and they inject no noise into the environment. So, if you are thinking about a studio with just you and a microphone, you might want to look into one of these rather than an adapter for your computer.

When it comes to audio recording, you get what you pay for. If you're doing lots of critical recording, it makes sense to spend the money on a professional machine. A recorder with XLR connectors, good mic preamps [Hack #14], reliable metering, and digital inputs and outputs or data transfer capabilities will make your life easier.

Consumer-level recorders have some downsides: the microphone inputs are usually mini-jacks, which can make unreliable connections; the built-in mic preamps are often noisy or not strong enough to record loud, clean signals from dynamic microphones; and there's a risk of losing your audio if the unit loses power while recording. The input volume controls are often problematic, sometimes offering only automatic gain control (AGC), which makes it easy to get a decent recording level quickly, but sudden loud sounds will often create distortion or unpleasant pumping artifacts.

AGC can be very useful for untrained recordists, especially nonprofessionals making audio diaries. It can also be a lifesaver in uncontrolled, "run and gun" situations where there's no time to twiddle with settings and you just need to get sound on tape. But in most cases, a stable recording level sounds better than one that's constantly adjusting to the input, so ideally, you want to set the levels manually and be able to turn them up or down as needed.

Here are some of the commonly used recording devices, and information about them:

iPod and iRiver

You might be able to record with the MP3 player you already own. Some small MP3 players allow audio recording, sometimes with optional add-ons. But check the specs carefully. Often the sample rate or bit depth is low, resulting in grainy or muffled sound, or the gain control is minimal, resulting in low-level or distorted audio. If your only option is recording to a compressed format such as MP3, you could have quality problems down the line if your audio is converted multiple times.

The iPod in particular produces low-quality audio. The standard sampling size is 8 bits and the sampling rate is 8 kHz. This doesn't result in quality audio. But there is an alternative. You can install Linux on your iPod (http://ipodlinux.org/) and boost the sampling rate to 96 kHz.

The small iRiver (http://iriver.com/) devices with line inputs are the choice of Greg Narain for his Beercasts [Hack #30]. These units are cheapthey cost around $100$200and they have a variety of memory and input configurations. They can record up to 44.1 kHz to MP3.

Solid-state recorders

The newer flash media or hard-disc recorders offer the advantage of a direct connection to the computer. Plug in a Universal Serial Bus (USB) or FireWire cable, or put the flash memory in a card reader and the drive will just appear as a volume on your computer's desktop. Then you can copy those files easily to your computer's drive for editing or archiving.

Several digital recorders offer professional or semiprofessional operation, ranging from about $400 to several thousand dollars. Edirol, Marantz, and Sound Devices make recorders with good mic preamps, some of them with XLR connectors for use with professional mics, pro-level sample rates and bit depths, and full-bandwidth recording of .wav files for maximum quality.

Digital dictation machines

Tiny digital dictation machines are tempting due to their size and ease of transferring recordings to a computer, but the sound quality is sometimes marginal.

DAT

DAT recorders avoid the hiss, wow (alternations between fast and slow), and flutter of analog tape, but they're expensive to buy and maintain, and still are subject to the vagaries of tape: occasional breakages, tangles, crumples, and head-wrap problems. And the format is increasingly rare these days, so finding parts, tapes, and repairs will be increasingly difficult and expensive.

Some portable DAT recorders require a special cable for digital output, and it's sometimes just easier to use the analog outs. Even if you're forced to do an analog transfer, you still have the sonic advantages of recording to a digital medium, with less noise and wider bandwidth than older tape-based media. And when done carefully, analog transfers can have minimal negative impact on sound quality.

Mini-disc

Mini-discs are still a popular choice, especially the portable consumer recorders. They are inexpensive, tiny, and easy to use, and while there is some data compression in the recording process, the sound quality is still very good.

Sony Minidiscs make it difficult or impossible to change the record level while recording, other machines beep when the record level is adjusted, and some have no manual record level at all, relying on the AGC to set the record level based on the input strength.

It's worth noting that despite the ambiguous terminology in product descriptions, the USB connections on the small mini-discs, except for the HiMD (High capacity MeDia) models, support only moving audio from the computer to the mini-disc, not the other way around, as most sound recordists would like. If you're using a recorder like that, the way to get sound to the computer for editing is via the analog outputs, in many cases the headphone out. That analog output is connected to an audio-in on your computer, built either into your soundcard or on an external interface.

MiniHD

The newer HiMD recorders allow uncompressed .wav recording, and even allow you to move the files as data to your computer over USB, but the process is unduly complicated and restricted, and not possible on all operating systems.

Pocket PC PDAs

Core Sound (http://core-sound.com/) has a card for Pocket PC PDAs called the PDAudio CF. The card is capable of recording 24 bits per sample at up to 192 kHz. At the sane rate of 16 bits at 44.1 kHz you can get 94 minutes on a 1 GB card, according to the vendor. There is a 1/8-inch stereo jack input for a microphone. The card sells for $199.

The equipment is changing everyday; in the end it's up to your ears what's "good enough." But keep in mind the recording format and the level of control. Full bandwidth is best, and the more control over recording levels, the better. Always record with the lossless pulse code modulated (PCM) or AIF formats, if possible.

It depends on what you need: if all you are looking for is intelligible audio, the size, price, and convenience of recording into an iPod or solid-state dictation machine might outweigh any quality compromises. A compelling story will overcome any technical limitations, and plenty of good productions have started from less-than-ideal field recordings. But a high-quality recording can more effectively transport listeners, and distortion or background noise can distract from the audio environment you're creating.

The small or nonexistent meters on consumer devices can create a problem, so experiment a bit to find what they really mean. You might need to record what appears to be slightly louder or softer than you would normally to get good levels. As with most digital recorders, "overs" sound really terrible, but very low record levels will sound bad in a different wayhissy and coarseonce they are brought up to the proper volume at the mixing stage. Get somewhere in the middle.

10.2.1. Get a Good Recording

To get started, use a good mic, which will probably make the biggest difference in your sound quality. If you're interviewing people in the field, a dynamic omnidirectional mic, such as the Electro-Voice RE50 or the Beyer M-58, is a reliable, easy-to use industry standard. If you know any musicians, a Shure SM58 is bound to be nearby, and can be a good interview microphone. If you need to isolate your subject from background noise, or record from further away, a shotgun mic such as the Sennheiser K6/ME66 combination is the best tool.

If you're recording environments or events, stereo can be a powerful tool. A small stereo mic with a mini-connector such as the Sony ECM-MS907 is a decent starting place, but more elaborate mics such as the Audio-Technica AT822, the Rode NT4, and the Shure VP88 can give better results with some practice. Simple voice interviews rarely benefit from stereo mic use; in fact, the changing soundstage can be distracting, even nauseating, if the mic is moved around rapidly. If the background sound is interesting while your interview subject is talking, stereo might be good. Just be careful to keep your mic as still as possible, with the main subject in the center of the stereo image.

Use the best recorder you can. Almost any recorder can do in a pinch, but the better the input connectors, controls, and metering, the more likely you'll be to get intelligible and pleasing sound. Practice with it before you go on an important interview.

Some recorders have built-in mics, and this can be fine for note-taking or transcriptions, but not as good for high-quality sound. It's rarely practical to hold the recorder up in an ideal position for any length of time, and an external mic is almost always of better quality than the tiny mics that are built in. On the other hand, the ease of use and speed of setup can outweigh any sonic compromises in some circumstances.

Get a good-quality microphone cable of an appropriate length (a little longer than your arm is a good rule of thumb). Then get another one as a backup.

You'll need a good converter cable if you want to connect a professional mic to a mini-jack mic input on the recorder. Broadcast supply houses have cables made for this specific purpose. You might want a right-angle mini-jack to maintain a better connection. Those jacks are notorious for wearing out, so if practical, leave the cable plugged in to reduce damage. Don't build a conglomeration of adapters and converters, since every added connection increases the potential for noise and short-circuits.

You might have trouble getting enough volume into consumer recorders from low-impedance dynamic microphones, such as the Electro-Voice RE 50. You can try a mic with a louder output, such as a condenser mic, but be sure you can provide "phantom power" with a battery in the mic, since the small consumer recorders that have mini-jack inputs cannot supply the needed charge for condenser mics. Another choice is to get the $50 Shure A96f cable, which raises the impedance of a low-impedance microphone a bit, giving you some more volume without requiring extra power (it also converts from XLR to mini, so it might be the only cable you need).

One of the most important elements of a recording rig is a good set of headphones. Listening to what's coming into your microphone allows you to place the mic better, notice background noise you might otherwise miss, and verify that you are actually getting clean audio into your recorder. Any headphones are better than no headphones, but ideally you want a set that will isolate you from outside sound. The professional standard is the Sony MDR7506.

10.2.2. Tips from the Pros

Bring extra media, whatever you're recording to. Extra cassettes, DATs, mini-discs, or flash media can be a lifesaver. You never know when an interview will go longer than you thought, and you don't want to run out of recording time right as the interesting stories are flowing. Bring extra batteries, for both your recorder and your mic, if it needs batteries.

A good bag that will hold everything in an organized way can be a huge help, especially if you can leave it stocked with all your accessories so that you never get caught short. A camera bag is good to keep everything together and protect your gear from damage.

When you record people on the street, be sure to ask if it's OK to record them and to post the result on the Internet. It's best to get that in the recording and then cut it out for the released version, but keep it on your master copy.

Finally, observe the most important rule of field recording: listen! Don't trust that you're recording a good sound. Use your headphones and listen to what's coming into your mic.

10.2.3. See Also

• "Pick the Right Microphone" [Hack #13]

• "Mix Your Podcast in Hardware" [Hack #14]

• "Reduce Noise" [Hack #15]

• "Podcast in Surround Sound" [Hack #16]

Jeff Towne