Editor's Note: Audiophile Style community member George Graves has kindly allowed us to publish his five part series on high quality audio recording. This series is a primer that many audiophiles will find interesting and educational. It isn't a treatise, textbook, or master class designed to cover every detail in depth. As a music lover and audiophile I want to understand a bit more about recording, but I don't want to become a recording engineer. This series is right in my wheelhouse, and I hope it's in yours as well. - CC
Part One: Commercial Recording Quality (link)
Part Two: Recording Media
For most of the "stereo era" the choice of recording mediums to use was limited to one and only one, magnetic tape. When the digital age came upon us, it was still limited to only one choice, magnetic tape, although this time it was video tape in the form of U-Matic, VHS or Beta and other digital magnetic tape formats such as DAT. Professional studios even used large reel-to-reel digital tape decks, some with 2-inch wide tape. But for most of the years following the Second World War, it was analog tape running at 15 or even 30 ips (inches per second) with wide tracks taking up fully half the width of the tape (1/2 of a quarter-inch-wide tape for each of two channels or three tracks covering a piece of 1/2 -inch tape or 35 mm magnetic "film") to guarantee reasonable signal-to-noise ratios and relative freedom from dropouts. The machines were big, heavy, complex and expensive, but that was all we had.
Today, it's quite different. The choices available to even the amateur recordist are so varied as to be almost bewildering. Digital recording has benefitted from the advances in computer technology which is moving at a breakneck speed. The first casualty of the computer age was the practice of recording digital audio to magnetic tape. Computer hard drives became the norm for studios who gladly replaced their stands of multitrack digital tape recorders with racks of computer hard drives. These are used for both audio capture and for long-term storage (with suitable back-ups, of course). Now, solid-state memory is making inroads into the hard-drive-based recording camp. Solid-state memories have the advantages that they have no moving parts, have long storage life and can be physically very small. Expect this trend to continue until it has replaced hard disk recording altogether.
Example of a rack-mounted Solid State Recorder/player
As amateur recordists, we benefit from these computer-based innovations in a number of ways. There are portable devices available which use a myriad of formats and media that cover just about everything from MP3 recording from a live source, all the way to the very sophisticated and flexible DSD (Direct Stream Digital) with it's 2.8 or 5.6 MHz sampling rate. The equipment required ranges from laptop computers to tiny solid state recorders, some, not much bigger than a pack of cigarettes. Let's examine some of the more popular and accessible options.
Using a Computer as a Digital Recorder
Since most people have a laptop computer of some description laying around, this would seem to be the cheapest and easiest path to digital recording. Certainly, the software to do this is in abundance, and one of the better programs, Audacity, (http://audacity.sourceforge.net/download/) is even free. Available for Windows, Mac, and Linux, this program gives you all the tools you need, save one, to use your computer as a digital recorder. The one tool missing is an outboard analog-to-digital converter. It takes analog signals in from the mixer or microphone preamps and outputs a digital signal in the required format. It needs to communicate with the software on the computer, and for this the interface between computer and A/D converter needs to be via a two-way bus such as USB or Firewire. All modern computers have USB 2.0, but few use Firewire. Unfortunately, the current USB standard, USB 2.0, is bandwidth limited and even two channels of 24-bit, 96 KHz digital audio is a stretch. While USB is fine for 44.1 and 48 KHz digital audio, even at 24-bit, it's just too slow for the higher sampling rates. Some implementations of USB use "tricks" to defeat the master-slave protocol on USB to allow it to work at 24-bit, 96 KHz, but the conversion is slow, causing a delay between the capture and the digitization of the audio stream. This delay is called latency and it makes monitoring the digital signal very difficult because it can be many seconds behind the performance being recorded. Therefore, for anything greater than a 48 KHz sampling rate, it is advisable to use Firewire. Firewire 400 is faster than USB 2.0 in the continuous transfer mode because it is a peer-to-peer protocol that doesn't have the computer overhead of USB. This reduces latency and even allows for the transfer of two-channels of digital audio at 32-bit, floating point and 192KHz sampling rate.
However, the problem remains that most computers don't come with Firewire ports. If you use a desktop computer, you can always purchase a Firewire PC card to go in it, but if you are doing location recording (as opposed to having your own studio), this makes the prospect of live recording about as appealing as the days of lugging huge reel-to-reel analog recorders around. Laptops are the preferred computer here, but these days, only a couple of Sony models and Macbook Pros have Firewire ports built-in. Some of the more expensive Windows Laptops sport PCI Express slots and these allow one to add third-party Firewire support to one's laptop, but either buying a Macbook Pro laptop or a higher-end Windows laptop with a peripheral card slot is an expensive proposition, and there are other alternatives.
Also, the outboard A/D converter can be expensive but at least here there are excellent inexpensive solutions, available as well. For A/D (and D/A) conversion of so-called "CD quality" recordings (16-bit, 44.1 KHz sampling rate), there are a number of USB interfaced converters available from companies like Behringer, Lexicon and Samson, some for less than (US) $40. Behringer sells an excellent Firewire computer interface box that has A/D and D/A converters, called the FCA202 that will accommodate up to 24-bit, 96 KHz audio for less than (US) $100 street price. I have used this converter with an iBook laptop and Audacity to make some truly spectacular sounding recordings.
Behringer FCA202 Firewire combination A/D and D/A computer interface is excellent quality and affordable with street prices less than $100
For years, Sony has sold its proprietary "Atrac" compression scheme in conjunction with its "Mini-Disc" transport and media system for portable recording and playback. While "Atrac" arguably sounds somewhat better than MP3, it's certainly not what most of us would use to "master" live performances. About 7 or 8 years ago, Sony came up with an improvement to the format called Hi-Md. The improvements were threefold. First, the Hi-Md disc capacity was increased to 1 Gigabyte. This gave just short of 8 hours of Atrac recording and playback at the highest 256 kbps "Hi-SP" Atrac3+ setting. Secondly, Sony improved it's compression algorithms to "Atrac3+" which was a distinct improvement in sound quality, and thirdly and most importantly for our purposes, Sony added a linear (non-compressed) 16-bit, 44.1Khz PCM recording ability to the format which gave 1 hr and 34 minutes of CD quality audio on one Hi-Md disc! These devices can make excellent recordings, but there is one drawback. If you didn't buy the top-of-the-line recorder/player, there was no way to physically transfer the resultant digital recording from the Hi-Md recorder to one's computer! All you could do was to output it as an analog signal and re-digitize it (in real time) as you write it to your computer's hard drive.
The Sony Walkman MZ RH-910 Hi-Md MiniDisc recorder/player shown here with an M-S electret condenser microphone
In the last five years, a new type of portable recorder has appeared. Taking their cue from digital cameras, these small, hand-held recorders use the same kinds of solid-state memories as cameras use to store the digital audio files. Lacking moving parts of any kind, these devices give excellent battery life and with tiny SD cards, are truly hand held. Most have their own microphones built-in, but will take external mikes. Some, like the Zoom H4 series, will take professional XLR microphone connectors and will even supply the 48-volt phantom power required by professional condenser microphones. Others will take only consumer grade outboard electret microphones connected via 1/8-inch "mini" phone plugs. All will accept line-level inputs from mixers and outboard microphone preamps, but most accept only consumer audio levels of -10 dBm. Many of these devices offer multiple recording formats ranging all the way from MP3 to 24-bit, 96 KHz PCM audio. But a lot of these recorders only record to 48 KHz, so one must be careful when buying. One of the smallest and most affordable of these devices is the Zoom H2 "Handy-Recorder". Capable of recording up to 24/96, this device sports four microphones of its own and can be used to record surround sound (although it is limited to 48 Khz sampling in this mode). At a street price of less of than US $200, one could use this device with an inexpensive mixer from Mackie or Alesis or Behringer and a couple of inexpensive big-capsule cardioid condenser microphones as one's primary recording system without any apologies to anyone. An even simpler system would be Zoom's H4n which has its own microphone preamps and powered XLR connectors. Then all you need is the microphones. Of course, you'd then limit yourself to only two, but the recorded results would be virtually identical to those obtained with the H2 and an outboard two-microphone preamplifier or mixer as the recording circuitry for the two units is identical.
I use an H2 as a backup recorder and it has come in handy on several occasions. I just connect it to my mixer with a stereo mini-phone plug to stereo RCA cable, and start it before the program begins and forget it. If anything goes wrong with the computer setup, I still have a 24-bit, 96 Khz recording.
These recorders are made by such companies as Alesis, Sony, TASCAM, Samson/Zoom, Korg, Marantz, Edirol, and M-Audio.
The Zoom H2 "Handy-Recorder" is capable of making high-resolution recordings at 24-bit/96 KHz
Mixers With Built-in Recording Devices
An alternative to a separate Mixer or microphone preamp and recording device would be a solution that combine the two into one unit. Some, like the Korg D888, use and internal hard disk to store audio directly. Others, like TASCAM's 2488neo, use both a hard drive and a CD burner internal to the unit. The downside of both of these units is that one is limited to 44.1 KHz sampling rate, although the TASCAM will record 24-bit to the hard drive. Zoom's new R16 will will act as 16 track stand-alone mixer and has 8 microphone preamps. It records to solid-state memory, or can function as a DAW interface to a computer using USB which limits its sampling rate to 48 KHz. While these can be effective at reducing clutter and simplifying one's setup, I find that they are restricting in that one cannot upgrade any part of the system (let's say that down the road, you find that you need more microphone inputs, for instance) without replacing everything.
Zoom R16. An Example of an "all-in-one" solution. 8-microphone inputs, built-in recorder to SD Cards up to 32 Gig, Limited to 24-bit, 48 Khz.
The Ultimate Recording Medium, DSD
Back around the turn of this century, Sony, responding to complaints from audiophiles that CD wasn't "good enough" came out with a new high-end format called "Super Audio Compact Disc" or SACD. The format used for recording these high-resolution discs was a departure from all other recording schemes then in existence. It was called DSD or "Direct Stream Digital" and instead of being the standard Pulse Code Modulation (PCM) used for CD and DVD-A (another high-resolution format), DSD used a single-bit process that employed a very high sampling rate of either 2.8 MHz or 5.6 MHz. SACD didn't succeed in the mass market, as most people felt that regular CD was "good enough", but it does have a following in the audiophile market and companies like Telarc, Mobile Fidelity, Virgin Records, and a number of others still record and release in this format. Korg, known for their recording and sound reinforcement equipment, sells three recorders that will allow the amateur recordist to capture performances in this ultimate of high-resolution formats. The three machines are called the MR-1, which is a small hand held field recorder about the size of a Zoom H2 (see above) the MR-1000 which is a larger field recorder about the size of a very thick paperback novel, and sports XLR microphone inputs, and the rack-mounted MR-2000. The MR-1 retails for about (US) $900, while the MR-1 retails for about (US) $1500 and the MR-2000 is about (US) $2000.
It is possible to regularly find MR-1s on E-Bay for less than $500 and I got mine for $299. Now, the DSD format and Korg's implementation of it needs a little explaining. Currently, there is no practical way for any home or amateur recording enthusiasts to make their own SACD discs. While there is software available for this, it is extremely expensive, the cheapest being around (US) $5000. However, the software that Korg supplies with their DSD recorders, called 'AudioGate', allows owners of Windows and Mac computers to "translate" the super high quality DSD master to any currently used digital audio format. This means everything from 24-bit, 192 KHz PCM all the way down to MP3. Think of the DSD format as the audio equivalent of the "Raw" format for digital cameras. One can store these DSD files on any hard disk and then transfer them to the MR-1 for playback in their native format, or make lower resolution copies to distribute to your "talent" (those who allow you to record them) or even to burn DVD-A's at 192, 176.4, 96 or 88.2 KHz sampling rates.
This is my preferred method of recording. The device is beautifully made, takes pro levels, has balanced line inputs and will transfer files over USB to one's computer. A couple of slight drawbacks of this device need to be noted here. One is that it uses an internal 20 Gigabyte hard drive. This makes the recorder somewhat fragile and it means that one cannot increase storage size. The built-in battery is also limited to about 2.5 hours of recording time and is not user replaceable. For my part, battery life is a non issue, because I always record in venues with electric mains power (after all the mixer needs mains power too). Also, unlike the MR-1's bigger siblings, it records at only 2.8 MHz, 5.6 MHz not being available on this unit. That's OK really as I have heard SACDs with samples recorded at both sample rates, and honestly, I defy anyone to hear the difference. Most commercial SACDs are mastered at 2.8 MHz.
I prefer the Korg DSD recorder to my old method of using my computer as a recording device because the MR-1 is so much simpler to use than the computer (which is actually, quite complex in it's setup). Forget to do any one of a number of "rituals" with the computer, and you might find yourself, as I did fairly recently, recording a large symphonic band with the computer's little built-in voice microphone instead of with the fine stereo mike that was on the stand in front of the group. OOPs! Luckily, I had the Zoom H2 connected to the mixer and it did record the ensemble properly. Always have a backup, if possible.
The Korg MR-1 can record in DSD, or PCM and is very flexible. It will make the highest quality recordings to which an amateur recordist can currently aspire and it's smaller and lighter than a laptop; simpler too!
Next time we'll look at mixing and microphone preamp options.