JBL GTO1220D
Owner's Manual

Connecting Your Subwoofer to Your Amplifier JBL GTO Series
JBL GTO Series subwoofers are available in two different con�gurations: as a single 2-ohm voice coil or as dual 2-ohm voice coils. Depending on the ampli�ers 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 ampli�ers. To achieve the maximum ampli�er output possible, you should design a speaker system that provides the lowest impedance that your ampli�er 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 ampli�erdamping factor (the ampli�er�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 ampli�er-output impedance. Therefore, connecting separate woofers in series reduces the damping factor of the ampli�er 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 ampli�ers 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 ampli�er 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 + 1 ... w w w
1 2 3

Figure 1. Parallel connection
RED STRIPE POS ( + ) BLACK STRIPE NEG ( � )

POS ( + ) NEG ( � )

Figure 2. Series connection
RED STRIPE POS ( + ) BLACK STRIPE NEG ( � )

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.

POS ( + )

NEG ( � )

03