Connecting Your Subwoofer to Your Amplifier J BL GTO Series

JBL GTO Series subwoofers are available in two different conﬁgurations: as a single 2-ohm voice coil or as dual 2-ohm voice coils. Depending on the ampliﬁers you are using, you may use either single-voice coil or dual-voice coil subwoofers in singles or multiples to maximize the power available from your ampliﬁers. To achieve the maximum ampliﬁer output possible, you should design a speaker system that provides the lowest impedance that

your ampliﬁer is rated to drive safely. When designing a subwoofer system, consider the following rules:

1.Don’t mix different subwoofer or enclosure types in the same system (use all single-coil woofers or all dual-coil woofers).

2.You may connect the coils of a dual-voice coil woofer in series, but we recommend that you avoid connecting separate woofers in series. The ampliﬁer- damping factor (the ampliﬁer’s ability to control the motion of the woofer) is expressed as a ratio of terminal impedance (the sum of speaker impedance, wire resistance and the D.C. resistance of any crossover coil connected to the woofer) to ampliﬁer-output impedance. Therefore, connecting separate woofers in series reduces the damping factor of the ampliﬁer to a value less than 1. This will result in poor transient response.

3.You must use both coils of a dual-voice coil woofer connected either in series or in parallel.

4.Most ampliﬁers deliver exactly the same amount of power bridged into a 4-ohm load

as they do running a 2-ohm stereo load.

To design a subwoofer system that maximizes available ampliﬁer power, keep the following rules in mind:

1.The total system impedance of woofers in parallel can be calculated using the formula:

Impedance = 1 + 1 + 1 . . .

w1 w2 w3

where w is the nominal impedance of the woofer.

2.The total system impedance of voice coils (or woofers) in series can be calculated using the formula:

Impedance = w1 + w2 + w3 . . .

The diagrams at right show parallel and series speaker connections.

Figure 1. Parallel connection

RED	BLACK
STRIPE	STRIPE
POS ( + )	NEG ( – )
POS ( + )
	NEG ( – )

Figure 2. Series connection

RED BLACK

STRIPE STRIPE

POS ( + ) NEG ( – )

POS ( + )	NEG ( – )

JBL GTO1220 Connecting Your Subwoofer to Your Amplifier J BL GTO Series, Impedance = 1 + 1 +

Models: GTO1220