In order to surpass the limitations of DAT tape, (16-bit maximum word length), and with the advent of the SONIC AD2K+, we have worked with computer professionals to develop a new field recording system. While the notion of recording to a laptop computer initially seemed relatively simple, given the availability of 24-bit recording software like Samplitude and Red Roaster from SEK'D and Sound Forge 5.0 from Sonic Foundry, many other issues had to be considered. While we share in pioneering this approach with other live recordists, we are aware that other systems are being implemented with various degrees of success. We welcome input from anyone attempting high-resolution or computer-based recording techniques. Based on experience with and feedback from our primary computer consultant, who has been experimenting with the system described below since late 2000, we are using the same setup.
While many laptops boast that they can be used for 4-6 hours, they do not specify the conditions of operation. Recording audio requires that the hard-drive function non-stop, not just when something is saved or searched. Truth is, 4-6 hours is optimistic under the presumption that all forms of power management are enabled. To the contrary, optimum recording stability and reliability are only achieved if all forms of power management are disabled.
As many laptops operate on 16-18 volts, a standard 12 volt/7.2 AmpHour lead-acid battery, even when run through a DC>AC power inverter or modified 12volt automobile cigarette lighter adapter, would only deliver 1.5-2 hours of operation--certainly not enough for extended comfort in the field or for those prone to back injury caused by toting undue quantities of batteries. Furthermore, any power solutions involving AC power inverters introduce alarming possibilities for RF interference and hum, thereby negating the benefits of high-end audio recording.
Other matters, like audio dropouts caused by simply opening and closing the display while recording ruled out many laptop, software, and operating system options. Additionally, as this machine is sure to go into rough environments, a small screen that is less prone to damage was desireable.
Enter the SONY VAIO (shown above) with its 8.95" monitor and Quad-Capacity Lithium Ion battery With 8-20 hours of operation promised, we can count on 8 hours while using the display and machine with no compromising power management enabled. SONY has achieved this unparalleled battery life through embracing Crusoe power saving technology. Still the entire machine remains equal in size to a full-sized portable DAT Recorder and only weighs about 4 pounds with the high-capacity battery connected.
The SONY VAIO Picturebook C1VN ("Very Nice," as we call it), is the most compact computer on the market. While the relatively small 12-Gigabyte hardrive, with nearly 4-gig used by the operating system and software, limits storage time to 8 hours of 24-bit/48kHz audio, there is seldom a situation where this will be a hardship for a field recordist.
Despite information posted here previously regarding USB interfaces, we have now recorded over 50 hours of audio using the Sound Devices USBPre and have found it to be as stable as any recording interface we have used. They are excellent for anyone needing a microphone pre-amp, phantom power, analog-to-digital conversion, and USB connection all in one package.
Comparatively, the VX Pocket from Digigram utilizes the PCMCIA slot and adapts to common audio interfaces, via a breakout cable, providing coaxial digital in/out and xlr analog input and output. Requiring minimal current to operate and safely tucked away inside the chassis of the computer, the VX Pocket seems to be the optimal card for digital transfer. Anyone considering using the VX Pocket as an analog interface should be aware that performing analog-to-digital conversion in close proximity to a CPU invites severely compromised audio quality. The noisy environment of the PC will reduce dynamic range and present audio masking problems or distortion.
While the VX Pocket offers 24-bit/48kHz analog-to-digital and digital-to-analog conversion, it pales next to the Lucid DA9624 for DA conversion and did not offer the quality of a/d conversion that the SONIC AD2K+ delivers. Once again these listening tests reminded us of the benefits of outboard conversion.
Although many speculate that IEEE-1394 (aka "firewire") is a significant contender, we have yet to see a portable high-resolution device. The MOTU 828 is a noteworthy unit for those who have consistent access to AC power.
If absolutely the best A/D conversion and microphone pre-amplification are demanded, a 24-bit/48kHz system can retain the same size and weight as an equivalent using package containing a full-sized portable DAT recorder. For those who simply want to experiment with laptop usage in the field, the Digigram VX Pocket accepts a line-level feed via XLR cables. This nicely accomodates high-end microphone pre-amps or balanced output soundboard feeds, while allowing for the addition of an outboard A/D converter.
We anxiously await the arrival of a 96kHz interface (although it is highly argued in pro audio circles that the transition from 16-bit to 24-bit is significantly more noteworthy than that of 48kHz to the higher sample rates of 88.2 kHz or 96kHz).
For immediate gratification, the recordings can be played back using the computer on which they were recorded. As the Digigram VX Pocket's offer 24-bit a/d and d/a conversion and includes a breakout cable with analog outputs, the VAIO can be connected directly to a home stereo system or studio monitors. For improved playback quality, and to really appreciate the benefit of 24-bit resolution, a nice Digital-to-Analog converter, like the Lucid DA9624 can be used by connecting to the VX Pocket's S/PDIF digital output.
While many of us quickly grew to appreciate CD's and then to enjoy the sonic improvement of DAT, one listener summed up the 24-bit experience as, "it's nearly as dramatic as the difference between a cassette and a DAT. By comparison the DAT sound mushy, undefined, and somehow, it nearly seems hissy." While that may be an extreme interpretation, no one who has visited our office to hear the comparisons has been less than impressed.
The previously mentioned Phil & Friends recording shows levels of clarity and detail beyond anything we imagined. In one noteworthy segment, the keyboard can be heard on the DAT but it is not until the passage is played from the computer that the articulation of each note is fully revealed. The instruments each have their own place in the recording and nothing masks or hides anything else in the mix.
While 8 hours of continous recording will be an unprecedented convenience in the field, the resulting files rapidly fill up the hard-drive. To move these files off the hard drive and free space for new recording mandates transferring them to some form of external storage. In the field, we will be using the SONY PCGA-CDRW52 External CD-RW drive. As a 24-bit/48kHz file consumes about 1 Gigabyte per hour, a standard 3-hour recording session will usually take up 4-5 CD-R's once the files are compressed using a package like Monkey's Audio Compressor which, like Shorten, delivers lossless compression. In turn, these compressed files must be divided into CD-R sized portions and recorded to CD. With the use of WinAce Archiver and NERO software, the task can be completed. These disks will be data files, NOT Red Book compatible CD's. They will only be playable through software applications that support 24-bit audio.
Once back in the luxury of the studio or editing environment, the files can be loaded onto a PC or back into the VAIO where all forms of editing may occur. Word-length reduction of the files to 16-bit via the aforementioned software packages, through the SONIC AD2K+, or available plug-ins, along with sample rate reduction to 44.1kHz can render Red Book compatible CD's.
Another solution for offloading files and storage will be through the use of ethernet, firewire, and USB network connections. This will enable the transfer of data from the VIAO to other computers with more available storage capacity
Additionally, assuming that the SONIC AD2K+ is used for recording, the 2K+'s digital-through can be used to record 16-bit DAT tapes or CD's (using a standalone burner) from the laptop. The recordist can simply play the audio files from the VIAO through the AD2K+ in digital through mode and select the word length reduction that best suits the listener's ear.
Once again, we anxiously await technology to arrive with cost effective, high-capacity solutions. We expect that DVD-R will make for a great destination to store these files without all the awkward manipulation necessary to store on lower capacity CD-R's.
As we are all looking to improve on recording techniques of the past and embrace the newest technologies, we will continue evaluating every option that becomes available with the promise of capturing higher-quality audio. We are well aware that the fundamentals of location, microphone placement, and the front-end of the system will remain as important as ever. 24-bit only promises to make the best of what we deliver to it.
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