Products of Interest

SPL Atmos 5.1/ASM 5 Surround Recording System

With all the interest in producing "surround sound," it is surprising that little attention has been paid to the direct recording of multi-channel audio. A joint project from German audio manufacturers, SPL and Dirk Brauner, the Atmos 5.1/ASM 5 Surround Recording System was created to enable direct "surround" recording. The package includes an array of five microphones and a rack-mount recording console (see Figure 1).

The microphone array is built using the Brauner VM1 high-quality condenser capsules. The polar patterns can be adjusted from the Atmos console in continuously variable configurations from figure eight to cardioid to omni. Based on the quasi-standardized 5.1 format, the front three microphones (Left, Center, Right) are attached to the central swivel at a distance of 17.5 cm, each able to be adjusted by as much as 90° each way along the horizontal axis. The other two (Surround Left, Surround Right) are 60 cm from the swivel, with a 60° adjustment range. The microphones can be adjusted electronically from the console using Spread and Divergence controls. The ASM5 array is connected via a custom multipin snake cable that is 25 meters long (longer lengths can be ordered).

The Atmos console includes +48 VDC phantom power and triple gain-stage mic preamplifiers using Lundahl input transformers. The multipin snake from the ASM5 array connects directly to the console, although there are separate XLR inputs that can be used for alternative microphone sets. There are also two stereo auxiliary inputs, individual outputs (balanced XLR and unbalanced ¹/₄-in), insert send/returns for each channel, and monitor and master outputs. Each channel features highpass filters switchable between 50 Hz or 100 Hz, and each can be routed to the five surround output buses or the direct output bus. Levels can be adjusted for each input, but it is also possible to place all five channels under a single master control for overall adjustments that preserve the relationships between individual microphones (a critical element in capturing a balanced surround audio image). Mono and bypass switches are provided to easily monitor individual microphones and to check for phasing issues. The console includes both a stereo headphone jack and a 6-pin DIN connector for Sennheiser Surrounder headphones.

The ASM5 array does not include a dedicated sub-bass element. A 130 Hz lowpass filter is implemented in the Atmos console so that low-frequency elements on any input can be routed out to become a subwoofer channel. The discrete outputs are designed to be routed directly to a recorder or workstation. No surround encoding is required.

The Atmos 5.1/ASM 5 is priced at US$ 27,990.00, and is also available from the distributor on a rental basis. Contact SPL Electronics GmbH, Sohlweg 55, D-41372 Niederkrüchten, Germany; telephone (+49) 2163-9834-0; fax (+49) 2163-9834-20; electronic mail info@soundperformancelab.com; World Wide Web www.soundperformancelab.com or www.g1ltd.com.

Sennheiser Surrounder Headphones

Sennheiser has contributed a rather unique product to the surround sound field. The Surrounder Sound Headphones do not enclose the ears, but instead rest on the listener's shoulders, "surrounding" the ears with four close-range loudspeaker drivers (see

Figure 2). The two drivers at the front reproduce the encoded "main front" channels, passing frequencies above 300 Hz. The rear drivers are broad-band, passing encoded "rear" channels as well as low frequency content. The optional SurrounderDSP incorporates a Dolby Pro Logic decoder to enable recordings, DVD audio, and games to be played back in properly spatialized form. The decoder comes with 15 preset "virtual-seating" options.

The Surrounder weighs approximately three pounds, and has a frequency response of 45 Hz-20 kHz. The signal-to-noise ratio is about 85 dB, with maximum SPL set at 100 dB. The total harmonic distortion is rated at 0.01%. The ¹Ž₄-inch cable connector enables the Surrounder to be used in conjunction with common audio equipment; a mini-jack adaptor...