ENG, EFP and Foley work demands high-quality mobile recording. In addition, the same recording may need to be provided in different formats for various clients or applications.
Despite the digital revolution, many studio engineers still make a safety archive master with analog tape because of its superior sound quality and because it creates an archive they can reuse to create a new digital master as formats change. However, even in a controlled climate, analog tapes continue to decay over time, and each time one is played, the quality can be compromised.
Korg has developed two new one-bit mobile recorders: the pocket-sized MR-1 and the studio-compatible MR-1000. Both units can record in various one-bit formats, including DSF, WSD and DSDIFF, as well as such traditional PCM formats as BWF with resolutions up to 24-bit/192kHz.
These recorders forgo removable media and record to an internal hard drive (20GB for the MR-1, 40GB for the MR-1000). A USB 2.0 connection allows recordings to be transferred to a computer and vice versa. The included AudioGate software converts files to any one-bit or PCM multibit format and allows file splitting or joining, gain adjustment and DC offset correction. It also creates smooth fade-ins and fade-outs.
One-bit recording is not new. Sony and Philips have used the technology as part of the Super Audio CD (SACD) format since 1999. More to the point, one-bit conversion is at the heart of most digital formats. Even in today's state-of-the-art 24-bit converters, the output of a one-bit A/D is subjected to real-time sigma-delta modulation, decimation and filtering in order to shape the data into multibit words that can be recorded and saved in the chosen PCM format. To play back the PCM recording, further interpolation filters are needed to recreate the analog audio signal. All of this processing and interpolation can affect the audio quality of the recording.
One-bit recording bypasses much of this processing. But there is a catch: The one-bit data stream must be recorded at a high sample rate in order to preserve the highest fidelity and dynamic range. Both of the portable audio systems record at the SACD standard of 2.8MHz. The MR-1000 doubles this sampling rate to 5.6MHz.
At such high sampling frequencies, both recorders can capture anything from a DC voltage up to 100kHz and can maintain a dynamic range of up to 120dB. This super-high sampling rate allows the noise floor to be frequency shifted into the audio range well above human hearing. Another benefit is the elimination of any steep Nyquist filtering that may have affected the audio or the encoding process.
Under the same conditions, one-bit recording can compete with and even exceed current multibit formats in terms of frequency response and dynamic range. However, one of the biggest advantages of one-bit recording is in mastering and archiving. Analog tape can accurately capture frequencies up to 50kHz. One-bit can double this. And unlike analog masters, one-bit masters can be safely stored without degradation. In addition, one-bit masters can be archived in their native format and reused for various applications. For example, with Korg's AudioGate software, users can take the one-bit file and create a 16-bit/44.1kHz master for a CD, a 24-bit/48kHz DVD-Audio master, a 24-bit/192kHz track to import into a ProTools session, or a master in new formats when are developed and adopted.
When you have only one chance to capture a great performance, Foley effect or interview, the MR Series will reliably yield the high-quality audio with the versatility of both one-bit and multibit PCM formats in a single unit. The AudioGate software can also translate the one-bit recordings to match your computer's audio hardware, so you can listen in real time.
Both recorders include an AC adapter and can run on battery power. (The MR-1 uses a rechargeable lithium battery. The MR-1000 uses eight AA batteries.) Both include a soft carry case for protection in the field.
Malcolm Doak is a product manager at Korg USA.