Portable audio recording equipment

I make audio recordings of meetings; I interview people and record those interviews; and I record narrative voiceovers for video productions and multimedia. Those processes are dealt with in other essays in this section of my site. Here, I have gathered and centralised information about the kinds of equipment I use and recommend.

The simple digital pocket recorder

Olympus DS-50

The Olympus DS-50 is an example of a high-quality convenience digital voice recorder, which may be all you need for simple audio interviews.

Is your primary reason for recording to help produce a written account of the meeting or interview afterwards? In that case your main concern is to capture the essence of what was said with the least amount of difficulty, and make it as easy as possible to transcribe; the technical recording quality is not so important.

For small meetings and interviews, a pocket digital recorder with built-in microphones can do the job, and you can buy something rather excellent for about £200. For a few years I have carried an Olympus DS-50 recorder around with me, and some of the recordings I have made with this have been good enough to podcast.

The DS-50 is no longer available but several enhanced machines of the same pocket-friendly size are available in the same price range. In particular I would recommend the Olympus LS-10 which improves on the DS-50 with more internal memory, an SD card for expansion memory, better stereo microphones and a choice of various sampling rates — and either compressed or uncompressed file formats. The LS-10 also can work with certain Olympus external microphones: a highly directional one, or a stereo pair of omnidirectional ones. A similar machine is the Yamaha Pocketrak CX but I have no personal experience of this, whereas I am impressed with the user-friendly interface and controls of Olympus equipment.

To get the recordings into the computer for editing is an easy matter, as the recorder connects via a USB cable and behaves as if it were an attached file storage device. Recordings copy across in seconds.

When audio quality matters:
portable ‘system’ recorders

Capturing really good quality audio becomes more important when the intent is not just to have an aide-memoire for writing something up after, but you actually want to put audio of a lecture on the Web in ‘podcast’ format, or perhaps record audio for integrating into a video or multimedia production.

Quality recording starts with a decent microphone. The microphone is to an audio recorder what a lens is to a camera. Would you use a dirty beerglass as a camera lens? No — and not only would you want a decent lens, you’d want the right lens for the job (telephoto, wide-angle and so on). The professional photographer favours a ‘system’ camera that can work with interchangeable lenses, and a similar case can be made for choosing a ‘system’ audio recorder that works with interchangeable good quality microphones.

In recent years I have gravitated towards digital audio recorders which can capture input from one or two good-quality microphones — or alternatively, tap the ‘line level output’ that can be extracted from some public address systems, from the base-station of a radio mic system, or from a mixer desk.

Marantz PMD650 MiniDisc recorder and microphones

My first ‘system’ audio recorder was a Marantz PMD650 MiniDisc machine, shown here with one of my Røde condenser mics and my Sennheiser short shotgun mic in a Rycote pistol-grip shockmount handle. The left and right input channels have independent manual gain controls.

Starting in 1992, when I was recording and transcribing meetings of the Information Design Association, I made the switch from magnetic tape to digital recording, which at the time for me meant MiniDisc. These little re-usable optical disks, written to and read with a laser beam, are a random-access medium. I reasoned that this would be advantageous for transcribing audio recordings, a process which involves a lot of pausing and rewinding that might wear out a tape mechanism.

My first two MiniDisc recorders were essentially small consumer-grade machines with a 3.5 mm jack socket for a simple stereo microphone, but in the late nineties I became aware of a more professional class of kit, designed with the radio journalist or field recordist in mind. Doing my research, I hit upon a list of desirable field-recorder characteristics which I have found to be just as true now I have switched away from MiniDisc to solid-state devices:

  • Pro microphone support. This means three-pin XLR connectors, so you can use shielded cable that is immune from radio-frequency interference; and ideally the ability to switch on a supply of 48 volts of ‘phantom power’ to drive studio condenser microphones.
  • Decent pre-amps. Beware, some digital recorders were designed on the assumption they’d be used by music bands to capture rehearsals and live gig performances. Those guys are LOUD and their input needs little pre-amplification. For interviewing, reportage and recording meetings, you need onboard pre-amp circuits which are more powerful, but which do not add much circuit-generated ‘noise’ to the input.
  • Manual gain control. The dictaphone-style devices may have a choice of sensitivity settings but otherwise rely on automatic adjustment of the degree of amplification (‘gain’) that is applied to the incoming sound. Ideally I want a fingertip-adjustable, easy to operate dial to adjust the gain manually, and separately for the left and right channel if I am recording with two mics.
  • Usable interface and controls. For a while I used a Zoom H4 solid-state recorder. The physical controls were fiddly, the LCD control display was hard to read. From that point on I have put usability high on my list of requirements. Moral: don’t buy something you haven’t physically seen or at least read a good review of!
  • Monitoring. There are two ways to monitor while recording. One is to wear headphones, so you hear what you’re capturing, but beware of the possibility that your gain setting could be set too low, and (subjectively) compensated for by a high headphone output setting! That is why good recorders also show the inputs visually, as a series of LEDs or bars in an LCD display (or both).
  • ‘Field-capable’. Ideally you want to be able to operate for a decent length of time away from a mains power supply, and to record for a long time without changing media.
  • Convenient audio transfer. It should be easy to transfer the recording to computer for editing, with no loss of quality. Best of all is if you have electronic media memory cards, because then you don’t need to have use the recorder itself in the audio transfer.

From MiniDisc to solid state

I have owned two MiniDisc recorders in this class, a Marantz PMD-650 and an HHB MDP500 Portadisc. These were good machines, but the MiniDisc format was limiting (70 minutes in stereo or 140 minutes mono). When recording a day-long event, there was a slightly panicky moment changing discs between speakers. These recorders were also fairly bulky, could not run on batteries for that long, and (alas) being machines with moving parts, both eventually fell sick and died.

Another drawback of those machines was that making a transfer of the recording to computer essentially meant playing out the recording across a digital (S/PDIF or USB) wired link, dubbing into a recording system on the computer (I have long relied on QuickTime Pro, which is the paid-for upgrade to Apple’s QuickTime Player software). Dubbing a 90-minute recording across therefore took 90 minutes!

Marantz PMD661

Marantz PMD661 digital field recorder: my current gear, and I am well satisfied with it!

When it came to replacing my HHB MiniDisc with an equivalent solid-state system field recorder, my first attempt was a failure (the Zoom H4). A year later, at the beginning of 2010, I pushed the boat out a bit and for slightly under £500 I bought a Marantz PMD661, having read a number of good reviews.

I have written elsewhere about why after my bad experiences with a Zoom H4 I chose this machine, and what its desireable properties are, so here I will say only that it is a solidly-built machine which works with all sorts of microphones in my collection, has excellent pre-amps, runs for long sessions on four AA cells (including NiMH rechargeable ones), handles microphone or line input, provides phanton power if required, saves its files either in uncompressed WAV or else MP3 format on SD cards, and has an easy to use interface.

To transfer the recordings to computer, I extract the SD card and pop it into a media card reader attached to the computer, and the files copy across in minutes. One 8-gigabyte card generally gets me through a full one-day conference.

If I have one criticism of the PMD661, and it is only one, it is that the concentric manual gain control knobs have a lot of stickiness between them, so it is difficult to turn the gain of one channel against the other (for example to mute one of two attached mics); it is definitely a two-handed operation. A better machine, from this and some other points of view, might be the Tascam HD-P2, but that is both significantly more expensive and more than twice the size.

Adding a pre-amp or mixer desk

Recording kit including Alesis mixer desk

Conference recording kit as used in July 2011 for the ISKO UK conference. [A] is an Alesis mixer desk providing pre-amp power to the mics, adjusting the tonality of each channel and sending a mixed signal to the Line Out ports. [B] is the Marantz solid-state recorder taking input from the Line Out on the Alesis. [C] and [D] are the tried and trusted mics; and I am able to monitor the recording levels through LED gain meters on both the black boxes, while also listening in with my comfy Beyer DT-100 closed-back headphones.

IF I WANT TO TRAVEL LIGHT, all I will pack is the Marantz PMD661, a short XLR cable, several changes of NiMH AA cells, a zipped bag with my Sennheiser and Beyer mics and a lightweight folding table stand. If I am doing a serious recording job at a conference, using the two-mic technique that I describe elsewhere, I will add a pre-amplifier — if for no other reason than that the gain control knobs are easier to manipulate than on the Marantz all by itself!

Very recently, I purchased a small-ish Alesis ‘Multimix 8 USB FX’ mixer desk which is several things in one. Here are the aspects that are significant to me:

  • Pre-amp with phantom power: This desk can power and amplify input from four separate microphones. This would be very useful if you were doing a round-table studio discussion, because the mics could be ideally positioned for each speaker.
  • EQ, balance and mix: Each channel can be adjusted to balance the bass, middle and treble frequences independently, something no field recorder can do unaided. Each channel has its own gain level and filters, and then there is a big knob to trim that channel within the mix (sliders would be cooler, but tend to come on more expensive machinery. I also appreciate how each channel can be positioned within the mixed stereo output: to the left, to the right or centrally.
  • Line Out: For Public Address or music applications, you would route this output to an amplifier. For recording, I route this to the digital recorder.
  • USB Digital Out: The Alesis contains an analogue/digital conversion circuit, and so you could use a laptop computer as a recording device if you like. Alternatively, I may be able in future to use the Alesis plus a laptop as a gateway to live audio streaming of an event over the Internet.

Microphone types

A dynamic microphone is so called because a magnet moving inside a coil directly produces the electrical signal that represents the sound. These mics don’t need external power, are quite robust and tend to be reasonably priced. They don’t ‘overload’ (distort the sound) much at high volumes, but they are prone to generating their own small amount of background hum, which will show up if recording quiet sounds and strongly amplifying them. Their premier use is as a stage vocal mic.

Inside a studio you’re more likely to find a diaphragm condenser mic. The diaphragm which captures the sound waves modifies the electrical resistance of the mic, which must be powered externally (either by a battery or with ‘phantom power’ through the mic cable). Delicate, and sometimes very expensive, they are prized for their excellent signal-to-noise ratio and fidelity of response across the whole range of audible frequencies. I have a couple of Australian-made Røde NT-1 mics, moderately priced at about £130 each.

Other specialist microphones use some variety of condenser pick-up. A Lavalier microphone is so small that it can be clipped inconspicuously to clothing, and is often used as the pickup of a radio microphone rig.

Microphone directionality

Where people speaking in a meeting are sat all around a table, a single omni-directional microphone may be the simplest choice. One design of low-profile omnidirectional microphone called a boundary effect mic exploits the fact that sound-pressure increases near a hard flat surface like that of a table, and is very useful in these situations. (They are also often installed on the walls of police interview rooms.)

If you are recording a speaker at the front of a meeting, you’ll prefer a directional microphone, the recording capsule of which is designed to reject sound coming from behind. These are also called ‘cardioid’ microphones because the pick-up pattern, represented by lines to indicate the strength of signal received, looks in cross section like a heart. Microphones with a more emphatic orientation towards the front are called ‘hypercardioid’.

For extreme directionality, film-makers and news reporters prefer a shotgun microphone. Often, for outdoors work, the thin tubular mic is suspended in a shock-proof cage, wrapped in a furry windshield looking like a hairy guinea-pig, and hoisted into position aloft a ‘fishpole’. I have a Sennehiser K6/M66 short shotgun, which I bought second-hand from a film-maker, and which I have extensively used with my camcorder. An equivalent modern short shotgun mic would be the Beyer MCE 86, tweaked for voice applications, at about £215 plus VAT. There is a cheaper version, but this one — like my Sennheiser — has its own battery compartment and so does not rely on phantom power.

Shotgun mics are sensitive to wind interference, so for outdoor use they are often enclosed in a wind protection capsule. I have a less expensive Rycote ‘Softie’ furry windshield. It came in a kit with a shockmounted pistol grip, which actually sees a lot more use than its furry companion.

Cables, plugs and mic power issues

XLR versus Microjack

Professional microphones connect to recorders using shielded cable and three-pin XLR connectors. Compare the 3.5" microjack typically used by consumer gear.

A consumer microphone usually has a thin, unshielded cable ending in a jack plug. It will also be short, because a longer unshielded cable could pick up radio signals (you don’t want to find yourself recording the local taxi company!); and the small jack plugs are often a source of crackling.

Professional microphones usually connect via a locking three-pin XLR socket to a shielded co-axial cable. Shielded cable runs can be quite long — when recording meetings, I often place a microphone by the speaker’s podium, with up to 15 metres of shielded cable between there and where I’m sitting in the hall.

To exploit this system, your recording apparatus will also have to have XLR connectors like the Marantz and HHB recorders already mentioned, or the Alesis pre-amp/mixer. Most professional recorders will also send 48 volts of ‘phantom power’ through the cable to drive those condenser-style microphones which don’t have their own internal battery to power them.

Supporting your mic: handheld scenarios

One major challenge of audio recording is ensuring that the sound your microphones capture is not ‘polluted’ by vibrations transmitted from a floor through a mic stand, or friction from the hand which holds the mic.

A portable field audio recorder could be used in a wide variety of situations. As an early waker, I often listen to ‘Farming Today’ or ‘Open Country’ on BBC Radio 4, where the interview is very likely to take place in a milking shed or while climbing a hill. This requires a hand-held microphone, and for years I was challenged to find one which was not vulnerable to transmitting handling noises along the stem of the mic and into the recording capsule.

Beyer MCE 58 microphone

The Beyer MCE 58 is an omnidirectional mic designed for reporters in ‘ENG’ (electronic news gathering) situations.

Late in 2010 I solved this problem by purchasing a Beyer MCE 58 microphone, which was designed as a reporter’s news gathering instrument, responding best at human voice frequencies. It is a condenser microphone powered by an AA battery. Omnidirectional, it does not have to be ‘pointed’ at the subject. The Beyer is amazingly immune to wind noise and handling noise: the capsule is suspended in a sophisticated internal shockmount. I once handed it to a six year old so he could make a presentation to video camera, and despite his heavy handling of the mic, the sound came through perfectly!

A drawback of the Beyer is that you do need to get in pretty close to your subject’s mouth (indeed, its relatively long stem is designed to facilitate that); and as an ‘omni’, it picks up lots of ambient noise. For such situations, I switch to my short shotgun Sennheiser, mounted in the Rycote pistol-grip, which has a rubber cradle as shockmounting. The handle also has a groove into which you anchor the mic cable so that it does not drag on the mic and transmit handling noise.

Supporting your mic: stands and shockmounts

When I am engaged to record a lecture, I am usually using one of my Røde studio condenser mics at the speaker’s position, mounted on a microphone stand with a boom arm that can reach over the lectern. These microphones are very sensitive to shocks, and someone walking over the floor, if it makes the stand vibrate, can pollute the recording. The answer is to suspend the mic in a shockmount, a collar that is anchored to a containing cage with a ring of rubber bands. You should also beware of the ability of shocks to be transmitted to the mic through its cable, and tie up the cable to the stand rather than let it trail straight to the floor or table.

If you must place a mic stand on a table and you don’t have a shockmount, do at least place a felt mat or foam rubber pad underneath the base. (In a pinch, a thick mouse-mat will do.)

Recording direct to a personal computer

If you want to save some money on recording gear, you have a PC or laptop, and all of your interviews will be conducted at a table or desk, you might consider recording direct to a hard disk by connecting a microphone to your computer, which these days means to the USB port. You should either use a quiet machine, or place it well away from the mic.

On the hardware side, one possibility is to buy a USB microphone. In the era of podcasting there are quite a few makes available. Or if you have a professional mic with an XLR connector and its own power supply, Maplin sell a clever five metre cable that is XLR on one end and USB on the other, and does analogue-to-digital convertion, at a very reasonable twenty quid. At the fancier end, there are various pre-amp mixers like the Alesis which connect to a computer either via USB or FireWire.

On the software side, you’ll need software which can record input from the USB port. On a Macintosh laptop, I simply use QuickTime Pro. My understanding is that Audacity can also record from such USB microphone systems.

While I cannot see recording direct to a personal computer as a truly portable, robust solution (e.g. for recording an interview in the street), it may work very well for recording lectures at meetings, or desk-based face-fo-face interviews.