SPDIF to AES CONVERTOR

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SPDIF/TOS - AES

Murraypro offers this attractive, elegant, compact and low cost unit as an aid to incorporating low cost equipment, with SPDIF digital output, within the AES/EBU professional digital environment.

Often, prospective Users are drawn to a range equipment manufactured by a Company such as Tascam, for example, because of the wealth of attractive features and sound day to day performance available at realistic pricing. Sometimes such equipment, however, may only be provided with the "Consumer" SonyPhilipsDigitalInterFace output on a phono connector, which is quite unsuitable for direct connection within the Professional Studio environment.

The Cat: 356 Buffer Card Kit is designed to be fitted within existing commercial audio equipment fitted with SPDIF digital OP on a phono socket. The new card correctly terminates the SPDIF interface within the equipment, actively buffering the signal, providing voltage level shifting, output impedance matching and finally ac coupling transformer drive to the external dedicated AES/EBU digital equipment via an XLR3-M connector. Thus providing a transparent interface with the external digital input. The modest power requirements of the card are drawn from the host equipment, removing the requirement for a separate external power supply.

The kit consists of the fully tested interface Bd, wiring harness with IDC connector fitted, XLR3-M, and an assortment of mounting components. Only the supplied XLR3-M output connector requires fitting to a suitable space on the rear panel (even the nuts and bolts are supplied), in a hole easily punched with a standard "Q-Max" cutter, the board being fitted with specially manufactured self adhesive PCB mounting clamps.

The Cat 356 fully conforms with the output requirements of the AES 3: 1992, Specification, requiring that equipment output is wired as a single, transformer coupled, 110 ohm load. If +5V (at 50mA) is already available within the host equipment, the local regulator may be bypassed, and system power fed directly; otherwise the on-board regulation will provide local +5V from any convenient system power source between +8V and +30V.

The card functions automatically at the 32, 44.1 or 48KHz standardised sampling frequencies with out any adjustment.

The Cat 356 does not attempt to convert the signal protocol, or to alter the contents of any of the control/channel status blocks in any way whatsoever. It should be noted that an SPDIF protocol output data-stream with certain bits set might well prevent unauthorised "digital" dubbing whilst in the Consumer environment, however Professional equipment is usually designed to strip out and ignore these inhibitions whilst working in the AES professional environment. No guarantee could possibly be given that this is invariably the case, and consultation with the Professional Equipment Vendor is recommended.

Murraypro offer a low cost, externally powered, free standing version of the Unit (Cat 325U), that is intended to be used as a UTILITY SPDIF - AES Convertor. The Cat 325U will be found particularly useful if the main equipment is leased, internal space is tight, or modification of the equipment proves undesirable or impracticable. The Cat 356U does NOT require a large or cumbersome "wall-wart" external PSU. The SPDIF-AES Converter is a compact 75 x 50 x 25mm nominal. The SPDIF input is simply fed to the BNC socket and the balanced AES output, on XLR3-M, appears alongside.

SPECIFICATION

Cat: 356

• Sample clock frequency: 32, 44.1, 48 KHz, auto operation.
• Input impedance: 75 ohms +5% (IEC 958)
• Input level: >200mV (eye height > 50%)
• AES Output: 110 ohms @ HF, ( >30KHz ), rising at audio frequencies > 5K ohms @ 1KHz.Transformer coupled.
• AES operational level: 2 - 7V pp, into 110 ohms
• Power requirements: > +8V @ 50mA. (board only)
• Stand alone Case: 241l x 161w x 35h (mm)
• Mains powered: 4 VA max @ 230V ac, 50Hz. Internal PSU. Internally fused at 63mA T

NOTE: Murraypro do not offer an AES to SPDIF converter because with short cable runs there is normally sufficient energy in an

ac coupled, transformer driven AES signal to correctly saturate the SPDIF input. Ie, in the vast majority of cases, one is not required!

© Murraypro Sept 2009