JL Audio Tuning Hint If you are using the A6450 to drive, Bass Boost Controls, Speaker Outputs

“LP” (Low-Pass):Configures the filter to attenuate frequencies above the selected filter frequency at a rate of 12dB per octave. This is useful for connection of subwoofer(s) to one or more of the A6450’s channel pairs in a bi-amplified system.

“HP” (High-Pass):Configures the filter to attenuate frequencies below the selected filter frequency at a rate of 12dB per octave. This is useful for connection of component speakers to one or more of the A6450’s channel pairs in a bi-amplified system.

2)“Filter Freq. (Hz)” The filter frequency markings surrounding this rotary control are for reference purposes and are generally accurate to within 1/3 octave or better. If you would like to select the filter cutoff frequency with a higher level of precision, consult the chart in Appendix B (page 15).

Tuning Hint: If you are using the A6450 to drive

asubwoofer system (“LP” mode), a component satellite speaker system (“HP” mode) or both, 80 Hz is a good baseline “Filter Freq. (Hz)” setting. After properly adjusting the “Input Sens.”, as outlined in Appendix A (page 14), you can fine tune the “Filter Freq. (Hz)” control to achieve the desired system frequency response.

BASS BOOST CONTROLS

1)“Bass Boost”: Found in the “Channel 5 & 6 Controls” section, this switch allows the user to activate a 6 dB boost centered at 48 Hz for channels 5&6. When the “Bass Boost” is activated, the inputs to “CH 5 (Left)” and “CH 6 (Right)” are summed to create a mono signal. The “Filter Mode” switch in the “Channel

5 & 6 Controls” section must be in the “LP” position for the bass boost to be functional.

2)“Remote Bass Port”: This port allows you to connect an optional remote boost knob (sold separately as JL Audio Model RBC-1) that can be mounted in the front of the vehicle. With the RBC-1 connected, the boost is no longer limited to 0 or +6 dB, allowing a variable range of 0 to +12 dB of boost to be selected.

SPEAKER OUTPUTS

The A6450’s speaker outputs are designed to accept 16 AWG - 8 AWG wire.

Each pair of the A6450’s channels are designed to deliver power into speaker loads equal to or greater than 2 ohms when using a “stereo” configuration and speaker loads equal to or greater than 4 ohms when using a “bridged” configuration.

Speaker loads below 2 ohms nominal per channel are not recommended and may cause the amplifier to initiate a protection mode which reduces power output.

BRIDGING CONSIDERATIONS

Bridging is the practice of combining the output of two amplifier channels to drive a single load. When bridged, each channel produces signals of equal magnitude, but opposite polarity. The combined output of the two channels provides twice the output voltage available from a single channel. The A6450 has been designed for bridging of its channel pairs without the need for input inversion adaptors.

To bridge a pair of channels, use the “Left +” and “Right –” speaker connectors only (the “Left –” and “Right +” remain unused). When bridged, each channel will deliver optimum power into a 4 ohm load.

When a pair of channels are bridged, they will deliver 150W x 1 into a 4 ohm load or 90W x 1 into an 8 ohm load. Operating a pair of bridged channels into a load lower than 4 ohms is not recommended.

Because a bridged pair of channels requires that both channels receive input, you need to connect both left and right inputs to the source unit. Connection of only one input will result in reduced power output, increased distortion and can cause the amplifier to overheat.

Do not do this!

When a pair of the A6450’s channels are operating in bridged mode, the output will be in mono (only one channel). This mono channel can contain right channel only information, left channel only information or the sum of the information from both the right and left channels. In order to achieve one of these options, configure the inputs to that pair of channels in one of these two ways:

1)Left Channel Only or Right Channel Only Information: If you wish to send a left-only or right-only signal to a pair of the A6450’s channels, use a “Y-Adaptor” to split the single channel signal into both left and right RCA inputs. This option is useful when using a pair of the A6450’s channels to drive left channel speakers only and the other pair of the A6450’s channels to drive right channel speakers only.

2)Left + Right Channel Information: When bridged and fed by a stereo input, a pair of the A6450’s channels will automatically combine the left and right channels into a summed mono (left + right) channel. This option

is useful when using a pair of the A6450’s channels to drive a subwoofer system or a summed mono center channel.

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