Channel Vision VC-302 User Manual

VC-302

Impedance Matching Volume Control

14

The VC-302 is an impedance matching volume control with an IR receiver
knockout. The knockout allows Channel Vision’s IR-2400 to be
integrated with the volume control for applications that require IR
repeating. The VC-302 comes with white, ivory, and almond knobs and
face plates to easily match other wall plates in the room.

Features:

!

Protects your amplifier against low impedance loads

!

Knockout for mounting Channel Vision’s IR-2400

!

Supports up to 8 pairs of speakers

!

Fits in a single-gang low-voltage ring or open-back j-box

!

Supports 14 - 20 AWG speaker wire

Bottom View

Input... Speaker wire connections
from your amplifier

R+ R- L- L+

R+ R- L- L+

INPUT

OUTPUT

Output... Speaker wire
connections to your speakers

Side View

2.63”

2.73”

White (included)

2

IR knockout...
Not visible from the front

Note: This product must be installed in
either an open ring or an extra-deep box.

8X8X4X4X1/2X

Impedance Matching Jumpers

1/2X

Accessories

Ivory & Almond conversion
kits sold separately

Ivory

VC-3IV

Almond
VC-3AL

Changing the Knob & Face Plate Color

Remove the existing knob and face plate.

1. Pull the knob off.

R+ R- L- L+

R+ R- L- L+

INPUT

OUTPUT

Gently press tabs from
back side using a flat blade
screwdriver.

2. Remove the face plate by pressing
on the 4 tabs that protrude through
the metal plate.

To install the new knob and face plate, simply reverse the process
shown above.

How Impedance Matching Works

Amplifiers have minimum impedance specifications for the speakers that
will be connected to them. This is usually 8 or 4 ohms. Most speakers
are either 8 or 4 ohms. Thus, most amplifiers are designed to drive one
pair of speakers. When additional speakers are connected in parallel
(wired to the same amplifier terminals) the resulting impedance is
reduced. This is why impedance matching volume controls are used.

The VC-302 provides three impedance magnifier settings: 1/2x, 4x, and
8x. These settings are used to magnify or compensate for low impedance
loads that result from wiring multiple speakers in parallel. Although the
calculations needed to determine the correct magnifier setting are simple,
you can use the chart below as guide to quickly find the correct setting for
your application. (Note: when no impedance matching is required, use
the 1/2x setting).

See chart for more information.

With no impedance matching

Number of 8 Ohm
speakers in parallel

2
3
4
5
6
7
8

Impedance

(Ohms)

4

2.66
2

1.6

1.33

1.14
1

With impedance matching

volume control VC-302

Magnifier

Setting

1/2X

4X
4X
8X

8X

8X
8X

Resulting

Impedance (Ohms)

8

10.64
8

12.8

10.64

9.12
8

Example:
If you have 4
pairs of 8-ohm
speakers
connected in
parallel, then
move the jumpers
to the 4X position
as on the
following page.

3