AUDIO

UNIVERSAL INTERFACE UNIT offering up to 24 channels

BAL>BAL, UNBAL>UNBAL, BAL>UNBAL & UNBAL>BAL,

as you decide, in 1U. Each buffer with individual + 12dB gain range.

.

NO restrictions on the mixture of the Bal/Unbal, I/O, or +/- dB gain function,

on ANY channel within ANY board.

It is, simply, TOTALLY FLEXIBLE

The Murraypro OCTAL BUFFER is an extremely flexible audio buffer designed for general interface use in the Broadcast Industry. The Unit has been designed to facilitate the interface of virtually any balanced or unbalanced audio source (especially at non-standard levels), with virtually any unbalanced or balanced destination; ie DVD, CD, U-Matic, VHS, etc to the balanced "real world".

Each Cat228 Board has 8 identical buffers, each of which is completely independent. The 1U Frame can hold up to 3 Cat228s, giving the possibility for example, of fully interfacing 6x Stereo Rec/PB VTRs in a single 1U Rack Unit!

The gain of each channel may be varied over a range of approximately +16dB whilst the card is fitted within the 1U frame. To reduce the risk of unwanted "screwdriver drift" in service, the cards are protected by a removable front panel, permitting access to the multi-turn gain adjusting resistors which enable levels to be set to within a fraction of a dB. Units are normally supplied with their preset gains set for unity, but may be ordered from Murraypro with gain pre-aligned for some different value.

The low distortion Buffers, which may be used balanced or unbalanced as required, are ac coupled and have a high input impedance and a wide frequency response. These versatile buffer amplifiers may be cross-wired to perform mixing, or even a matrix function, for example converting L & R inputs to M & S outputs, or vice versa. Matrix balance in this mode can exceed 50dB.

Audio inputs and outputs to/from the buffer are carried on identical "D-25" type male panel mount connectors. Murraypro supplies mating solder-bucket connectors and screw-lock covers. These are the preferred connector type since the full flexibility of the Octal Buffer is always maintained, whilst enabling the use of cost effective IDC wiring technology within the Frame. We always recommend that unbalanced inputs are wired as if they were balanced, ie with screened twin cable from the source, thus permitting the common mode rejection ratio of the balanced input amplifiers to be used to full advantage, for hum reduction on the input line.

SPECIFICATION

PCB228 Card

CHANNELS

8/16/24 identical channels. 1,2 or 3 card fitted per frame.

INPUT:

Balanced operation: Hi Z 0dBV.7 nominal level.

Unbalanced operation: -10dBV.7 > -5dBV.7 nominal levels

CMRR: 40 dB nominal minimum, for balanced input. Max 10v CM signal, with reduced headroom.

Coupling: Ac, + 50 v maximum, dc + signal

OUTPUT

• Level: nominal 0dB balanced
• Insertion gain: + 12dB nominal
• Freq resp: -1dB nominal @ 40KHz
• Freq resp: -3dB nominal @ 10Hz
• Distortion: 0.1% nominal max + 8dBV.7
• OP impedance: <50 ohms / leg
• OP current: + 10mA nominal
• Short circuit: Unlimited duration

ADJUSTMENT

• Gain: 20 turn resistor, accessable from Bd front.
• Nominal Range: + 14dB

HEADROOM

• Max: +26dB balanced output max level, bal IP or OP

MATRIX

• Balance: 2 buffers, cross coupled, >-40dB

POWER

• (dc: + 12v to + 15v (max), externally regulated)
• ac: 4VA nominal maximum @230V/50Hz

MODULE

• Front: 108W x 44H
• Depth: 220mm
• Connector: Din 41612 - ab

INTERFACE

• Connector: D-25pin, female panel mount buffer IN, (when supplied in standard 1 U case).
• Connector: D-25pin, male panel mount buffer OP, (when supplied in standard 1 U case).

+14dB gain, balanced or unbalanced, as required

1 of 8/16/24 IDENTICAL BUFFER CHANNELS

Input connections: Output connections: Unbalanced operation:

© Murraypro April 2006