Core Sound PDAudio Portable Digital Audio Recording System

Imagine a two-track recording system that stores high-resolution uncompressed audio on a memory card and fits in your hand. It is here now, and it works beautifully. Touted as a replacement for portable DAT recorders, PDAudio is a compact recording system for pocket PCs, laptop and desktop computers, and costs $400 to $1,000.
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Imagine a two-track recording system that stores high-resolution uncompressed audio on a memory card and fits in your hand. It is here now, and it works beautifully. Touted as a replacement for portable DAT recorders, PDAudio is a compact recording system for pocket PCs, laptop and desktop computers, and costs $400 to $1,000.
Product PointsApplications: Field, broadcast, project studio

Key Features: Compact Flash media interface; mic preamp; free software

Price: PD Audio-CF - $199 Mic2496 preamp - $499

Contact: Core Sound at 888-937-6832, Web Site.
Features

The system includes: A stereo mic preamp-A/D converter of your choice - such as Core Sound's Mic2496; an audio interface - Core Sound's PDAudio-CF (turns a PDA into a recorder by converting digital audio to CompactFlash format); a Personal Digital Assistant (PDA) of your choice - such as the Compaq iPAQ Pocket PC; an expansion card adapter for CompactFlash (CF) cards or PC cards; recording software - such as Core Sound's PDAudio Recorder, Pocco Software's Wichita, or Gidluck Mastering's Live2496 and a storage device - such as Flash memory (SD, PC Card, or CF card), PC-card hard drive or external hard drive.

The audio interface plugs into a PDA, notebook or laptop computer running the recording software. If a PDA is used, the recording is stored in a flash memory card, PC card or CF card hard drive, external hard drive or streamed to a network.

PDAudio-CF can be installed in PDA hosts that run Windows CE/PocketPC 2002/PocketPC 2003 or Linux (such as HP/Compaq's iPAQ,) or used with laptop and desktop computers running Linux, Windows 2000 or Windows XP.

A 1.5-inch square card, the PDAudio-CF is a Type I (extended) Compact Flash-S/PDIF interface. It accepts two channels of digital audio at 16-bit, 18-bit, 20-bit or 24-bit word length and 32 kHz to 192 kHz sampling rate. (Some PDAs support only up to 96 kHz).

On the interface card, a 1/8-inch phone jack accepts S/PDIF coaxial or mini TOSlink optical signals from any device that supplies them, such as a mic preamp/converter. The interface draws 45 mA at 96 kHz sampling rate. When installed in a PDA, the PDAudio interface operates on rechargeable batteries for more than two hours.

The user can transfer recordings as WAV files to a Mac or PC for use with most popular audio editing applications. This transfer can done in several ways: a removable memory card and a card reader, removable PC Card/CD Card hard drive, external 2.5-inch hard drive using a PC card interface, or wired and wireless LANs.

PDAudio-CF is priced at $199. PDAudio Recorder (Linux) software, an ALSA driver for Linux, a DLL driver for Windows CE/PocketPC 2002, and a WDM Audio driver for Windows 2000 and XP are available for download via the Web.

Core Sound offers recording software for the Linux operating system: PDAudio Recorder (Linux). It records and plays back up to 24-bit/96 kHz. The GUI indicates peak recording level, elapsed time, media capacity, battery status, CPU usage, WAV file characteristics and recording parameters. It also includes a file control screen, recorder transport controls, single-button recording and control-lock mode.

PDAudio Recorder (Linux) runs on the Linux Familiar/GPE2 operating system developed by HP Cambridge Research Labs for the iPAQ series of PDAs. See www.handhelds.org for the latest information. Linux Familiar is available for the HP iPAQ 3100-, 3600-, 3700-, 3800- and 3900-series. A version for the 5400-series is in development.

Third-party software companies have developed recording applications for PDAudio-CF and PDA's running Windows CE, PocketPC 2002 and PocketPC 2003. Two examples are Pocco Software's Wichita ($48) and Gidluck Mastering's Live2496 ($50).

Two other recording applications that will work with the PDAudio-CF interface are the Resco Audio Recorder and the PocketREC Portable Digital Audio Workstation. For PocketREC's release date, email Dave Buck at dbuck03@harris.com.

To work with the PDAudio-CF, most PDAs require a connector adapter called an expansion pack. It is a plastic cradle that piggybacks onto the PDA. The adapter provides two slots: one for the PDAudio-CF interface and one for the storage device. Four manufacturers offer dual card expansion packs for the iPaq: HP, Portable Innovation Technology, Seidio and Nexian. Details are at www.core-sound.com.

You will need a mic preamp and A/D converter to complete the system. Core Sound offers the Mic2496 ($499), a small, rugged two-channel mic preamp/converter running at 24 bits and up to 96 kHz. It includes an on-off switch, phantom power dual XLR and 1/8-inch stereo mini jack input breakout cables, dual level controls, LED level indicators, sample-rate switches, and both an 1/8-inch coaxial and a TOSlink optical S/PDIF output. The unit runs on an internal 9V battery (for four hours), an AC adapter or external battery pack.

IN USE

I reviewed a system made of these components:

Core Sound Mic2496 (stereo mic preamp/A/D converter); Core Sound PDAudio-CF (S/PDIF interface card); Compaq iPAQ 3835 Pocket PCr; PiTech Memplug Dual CF card expansion pack; Pocco Software Wichita recording software; Gidluck Mastering Live2496 recording software and a 1GB Compact Flash memory card.

To assemble the system, slip the iPAQ Pocket PC into the card expansion pack, which piggybacks onto the iPAQ. Then insert the PDAudio-CD card into one slot in the expansion pack, and insert a memory card into the other slot. Connect cables. Finally, plug headphones into the mini jack on the iPAQ.

Now turn on the iPAQ. On the screen, tap Start > Wichita. The Wichita recording software pops up. It's a simple GUI with transport controls, a non-scaled level meter, setup icons and a list of recorded files. Tap the icons to select the audio source, coax or optical input, and 16 or 24-bit sampling rate.

Alternatively, launch the Live2496 software. It has transport controls, a large scaled level meter, and selections for setup. An applet within Live2496 allocates large files (1 GB - 4 GB) for subsequent recording. This prevents updates to the File Allocation Table (FAT) while recording, which allows sustained error-free recordings up to 24/96 when using slower mass storage. When using fast flash memory, Live2496 can record at 24/96 error-free for up to 10 hours.

Next, plug in mics, power up the preamp, turn on the P48 power switch (for condenser mics) and adjust the preamp level knobs. The preamp's level meter includes two LEDs per channel that indicate signal presence and clipping. It is hard to tell how close you are to clipping, but the software meter can be used instead. Once levels are set, tap the Record button on screen. When done, tap the play button and enjoy.

At this point you can pull out the memory card, plug it into a card reader, and transfer the audio files to your computer for editing. Given a fast PDA and storage device, recordings made with the PDAudio system (played back on a desktop computer) sound clean and smooth, with no audible hiss, distortion or glitches.

The software is a work in progress. Although Wichita can record at 16-bit/44.1 kHz for an unlimited time, it cannot record error-free for long periods at 24/96. Live2496 software can record 24/96 files for an unlimited time, but cannot play back. (This will be changed in a future release.) Clicks and dropouts are audible during 24/96 playback, but they are Wichita playback artifacts - not part of the recording. (Still, this does not inspire confidence). For reliable playback at 24/96 on the PDA, Conduits Technologies, Inc. offers a very low cost player: Pocket Player 2.51 (see http://www.conduits.com/products/player).

The phantom power circuit in the Mic2496 preamp creates slight noise when used with dynamic mics, so turn phantom off when not required. Mic2496 has 53 dB of total gain - on the low side - but enough to work with high-output condenser mics. If you use dynamic or ribbon mics with quiet sound sources, the mixer's gain is inadequate for full-level recordings.

Also, Wichita's on-screen level meter lacks a scale and responds slowly due to latency. As for other drawbacks,there is no analog input monitoring function in the preamp or Windows software (the Linux recording application provides real-time monitoring).

Note: Not every PDA or memory card can be used for recording.

Summary

The PDAudio system offers a new paradigm of recording. It is compact and low-cost, offers pro-quality sound, and has no moving parts if used with a memory card. Highly recommended.