White Instruments 4926

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Summary

SOUND SYSTEM CONNECTIONS

Unbalanced Operation

Explains connecting signals independently for balanced or unbalanced use, minimizing noise.

Balanced Operation

Details balanced transmission lines for protection from EM disturbances and RFI noise.

WARRANTY POLICY

Warranty Repairs

Instructions for securely packing and shipping units for repair, including necessary documentation.

Out-of-Warranty Repairs

Details charges for repairs not covered by warranty and estimation procedures.

The White Instruments Model 4926 is a distribution amplifier designed for professional audio applications. It features two inputs and six outputs, allowing for flexible signal routing and distribution within a sound system. The unit is electronically balanced and interfaced with removable screw terminal connectors for both inputs and outputs.

Function Description:

The primary function of the 4926 is to distribute audio signals from its two inputs to up to six independent outputs. Each output can be assigned to either input 1, input 2, or a sum of both inputs, providing versatile signal routing capabilities. The unit also includes adjustable input gain and output attenuation for precise level control. It can operate with both balanced and unbalanced audio signals, offering flexibility in system integration. The active servo-balanced input and output circuits ensure high-quality signal transmission and rejection of common-mode noise.

Important Technical Specifications:

Number of Channels: 2 inputs, 6 outputs.
Frequency Range: 20 Hz – 20 kHz, ±0.5 dB.
Maximum Operating Level: +21 dBu.
Input Gain: Adjustable in 1 dB increments up to 15 dB using a 4-position DIP switch.
Output Attenuation: Adjustable in 1 dB increments up to 31 dB using a 5-position DIP switch.
Dynamic Range: >114 dB.
Distortion: Less than 0.01% into 600 ohms, 20Hz - 20kHz.
Crosstalk: Less than -90 dB at 1 kHz.
Input Impedance: 30 kΩ balanced, 10 kΩ unbalanced.
Output Impedance: 102 ohms balanced, 51 ohms unbalanced.
Input Circuit: Active servo-balanced, operable unbalanced with no gain change.
Output Circuit: Active servo-balanced, operable unbalanced with no gain change.
Connector Types: Removable screw terminals for inputs and outputs.
Power Requirements: 100-130 or 200-260 VAC, 50/60 Hz, 30 Watts.

Usage Features:

The 4926 is designed for ease of setup and operation.

Quick Start Guide: A step-by-step guide is provided for rapid installation and initial configuration, including mounting, AC voltage selection, input/output connections, output assignments, and initial gain/attenuation settings.
Input Gain Control: Input gain is set via a 4-lever DIP switch on the rear panel. A 0 dB calibration LED on the rear panel assists in setting appropriate input levels.
Output Attenuation Control: Output attenuation is set using 5 of the 7 levers in each output DIP switch on the rear panel.
Output Assignment: The remaining 2 levers in each 7-position output DIP switch allow for assigning each output to Input 1, Input 2, or a sum of both inputs.
Level Indicators:
- Front Panel: Each input has a green (0 dB) and red (clip) LED to indicate input levels after the gain stage. Each output has two green LEDs indicating 0 dB and -10 dB levels. A green LED indicates power.
- Rear Panel: A green (0 dB) LED for each input.
Balanced/Unbalanced Operation: The unit supports independent balanced or unbalanced connections for each input and output. For unbalanced operation, audio negative must be connected to signal common to avoid a 6 dB signal loss.
Grounding: The 4926 circuit common is tied to chassis ground via an internal jumper, which can be removed to isolate circuit common from chassis ground if needed. The manual emphasizes the importance of never removing the grounding lug from the AC power cable for safety and legality.
System Set-Up Procedure: A detailed procedure is outlined to maximize dynamic range and minimize audible noise, including setting input gain to occasionally flash the clip indicator and then adjusting output attenuation. It notes that if an output is assigned to a sum of inputs, the signal level may be higher than individual input levels. It also advises using as little output attenuation as possible to maximize dynamic range and reduce noise.

Maintenance Features:

Warranty: The White Instruments 4926 comes with a THREE-YEAR warranty covering manufacturing defects, workmanship, and original components, provided the unit has not been subjected to abuse.
Repair Services: White Instruments is the sole warranty repair facility in the United States. Authorized distributors handle warranty repairs outside the U.S.
Repair Process: For warranty repairs, the unit should be securely packed and shipped prepaid, including a copy of the sales receipt and a letter detailing the malfunction. Repairs are typically completed within 5 working days.
Out-of-Warranty Repairs: Charges apply for parts and labor for repairs not covered by warranty. Estimates can be requested.
Non-Profit Repair Center: White Instruments operates its repair center on a non-profit basis as a service to customers.
Shipping: Warranty repairs are returned prepaid via surface freight. Air freight returns are shipped freight collect.
Contact Information: Updated contact information is provided for mailing, shipping, phone, fax, and email, along with a website address. A note specifies that repairs and packages should be shipped to Suite 202.