Sifam AL29WF Audio Level Presentor VU-Meter

A low range ac voltmeter suitable for connecting across a 600 ohm line and self contained except for requiring an external 3.6k ohm resistor. Calibrated for use with a 3.6k ohm resistor 4vu above the scale marking so that the reference deflection (0vu) is produced by a signal 4vu above 1mW in 600 ohms (1.228v).

The performance of the meter is based upon the requirements of BS 6840: Part 17:1991, IEC 268 - 17: 1990. The dynamic characteristics quoted, which requires the response time to 99% of reference deflection (0vu) to be 0.3 seconds +/-10% with an overswing of at least 1.0% but not more than 1.5% are not fully met.

The overswing, because damping is not so tightly controlled but allowed to spread within normal design restraints, can vary between deadbeat to 5%. To specify the dynamic characteristics in terms of time to 99% of 0vu under such circumstances would give an unrepresentative measure of the speed of response. For this reason the time to reach -3vu with a steady reading of reference deflection (0vu) has been taken as a more realistic measure.

The following comparison can be made based on a rise time to -3vu with steady deflection of 0vu:

Conventional vu meter 0.13 - 0.15 seconds

AL19 0.14 - 0.18 seconds

AL29 0.16 - 0.20 seconds

AL39 0.17 - 0.21 seconds
 

Product – general description

The Presentor Audio Level Range of Analog Panel Meters complements the proven and popular industrial series. This series is available in three sizes each in four styles and offer a performance not significantly different from full specification vu meters to meet today’s audio market requirement for quality at affordable prices.

Features and Benefits

• Each of the four styles available can be provided for
• Front of panel mounting with full bezel
• Front of panel mounting with lower mask
• Back of panel mount
• Back of panel mount with accompanying frame
• Constructed with transparent acrylic front and high impact transparent polystyrene rear body molding.
• Masks and bezels are molded in black ABS.
• Taut band core magnet movement incorporated as standard with compact 26mm diameter barrel. This rugged movement makes these meters equally suitable for portable or fixed audio applications.
• There is no calibration effect when mounted on a ferrous panel. Pointers and dials
• Compatible replacement meter for the Urei 11767 / 1178 Studio compressor

The combination of tube pointer and flattened arc scale on translucent buff colored dial results in an easily read meter, even when monitoring a row on a large console. A white dial can be specified if required. The standard scale is based on the vu ‘A’ scale as illustrated in the above photographs, but the ‘B’ scale with the ‘percent’ reading at the top can be supplied to order.

Zero adjuster
Positioned on the rear as standard, but can be offered on the front

The SIFAM type AL29WF was the standard meter for the vintage Urei 1176 / 1178 compressors in earlier years. Buy it new as replacement meter or for many other audio units as well.