Russound TBL-75 User Manual

A/V DISTRIBUTION & CONTROL SYSTEMS

5 Forbes Rd. Newmarket, NH 03857

TBL-75

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A/V DISTRIBUTION & CONTROL SYSTEMS

TBL-75

Table-Top Volume Control

Instruction Manual

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Introduction

X1
X2

X8
X4

INPUT

OUTPUT

Newmarket, NH U.S.A.

MADE IN KOREA

L+ L- R- R+

L+ L- R- R+

X1
X2

X8
X4

The TBL-75 Stereo Volume Control is a free-standing table-top
stereo volume control with a front panel headphone jack and built­in impedance-matching capabilities. It connects between the
speaker-level output of an amplifier or receiver, speaker selector,
etc, and a pair of speakers. The application of the TBL-75 is to
adjust the volume of the connected speakers. The TBL-75 adjusts
the volume of the speakers connected to it by adjusting the signal
from the amplifier to the speakers. All Russound volume controls
are manufactured using a high-quality autoformer design.
Autoformers provide excellent frequency response and efficient use
of amplifier power.

Type of Speaker Wire

For most applications, we recommend you use 16 or 14 gauge,
stranded copper speaker wire for the TBL-75 volume control. For
wire runs longer than 100 feet, 14 gauge wire is recommended. Do
not use wire that is larger than 14 gauge, as it may not fit into the
connector on the TBL-75. Never use solid or aluminum electrical
wire. When running speaker wires inside the walls, most states and
municipalities in the U.S. specify that you must use a speaker cable
with a minimum fire rating of "CL-2" or "CL-3" Consult your
Russound dealer or electrician. Russound offers "CL-3" rated
speaker cable, which is multi-stranded and enclosed in temperature

-resistant PVC jackets specifically designed for this application.

Setting the Impedance Switch

1. Determine the minimum impedance capability of the amplifier.
Normally, this information can be found near the speaker output
terminals on the back of the amplifier (look for a measurement

in Ohms Ω).

WRITE THE MINIMUM IMPEDANCE HERE:_______

2. Determine the impedance of the speakers. Most speakers have
this information printed on the back near the speaker terminals.

Most speakers are 4Ω (4 Ohm) or 8Ω (8 Ohm).

WRITE THE IMPEDANCE HERE:_______
NOTE: If you are using speakers of different impedances, you

need to determine the average or common impedance. For

example, a pair of 4Ω speakers can be considered 2 pair of 8Ω

speakers.

TBL-75 Table-Top Stereo Volume Control

The Russound TBL-75 volume control is a combination of a
standard and impedance-matching control. When used with an
impedance-matching speaker selector, the TBL-75 volume control
should be set in the X1 position. The impedance-matching switch is
located on the back of the chassis of the TBL-75. In this position,
the speaker selector is providing the impedance matching and
protection. When there is no impedance-matching speaker selector
in the system, the impedance-matching switch must be set in a
position that correctly multiplies the impedance of the system to a
level that is equal to or greater than the impedance of the amplifier.
This will protect the amplifier from damage. Impedance-matching
switch settings can be determined by following the steps below.

3. Count the number of pairs of speakers connected to the
amplifier.

WRITE THE NUMBER OF PAIRS HERE:_______

4. By dividing the impedance of the speakers (step #2) by the
number of pairs of speakers (step #3), you can determine the
system impedance.

EXAMPLE: 8Ω speakers ÷ 4 pair of speakers = 2Ω system

impedance.

5. Determine the proper impedance-matching setting by dividing
the amplifier impedance (step 1) by the system impedance (step

4). Note: if the resulting number is between 2 and 4, use X4; if it

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