Bedienungsanleitung JL Audio A4300 (Seite 4 von 11) (Englisch)

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Do not increase any “Input Sens.” setting for

any channel(s) of any amplifier in the system

beyond the maximum level established during

the procedure outlined in Appendix A (page

14). Doing so will result in audible distortion

and possible speaker damage.

FILTER CONTROLS

Most speakers are not designed to reproduce

the full range of frequencies audible by the

human ear. For this reason, most speaker

systems are comprised of multiple speakers, each

dedicated to reproducing a specific frequency

range. Filters are used to select which frequency

range is sent to each section of a speaker system.

The division of frequency ranges to different

speakers can be done with passive filters (coils

and/or capacitors between the amplifier outputs

and the speakers), which are acceptable and

commonly used for filtering between mid-

range speakers and tweeters. Filtering between

subwoofer systems and satellite speaker systems

is best done with active filters, which cut off

frequency content at the input to the amplifier.

Active filters are more stable than passive filters

and do not introduce extraneous resistance,

which can degrade subwoofer performance.

The active filter built into each channel section

of the A4300 can be used to eliminate potentially

harmful and/or undesired frequencies from

making their way through the amplifier sections

to the speaker(s). This serves to improve tonal

balance and to avoid distortion and possible

speaker failure. Correct use of these filters can

substantially increase the longevity and fidelity

of your audio system.

1) “Filter Mode” Control: The A4300 employs a

12dB per octave filter for each pair of channels

(one filter for channels 1&2 and another filter

for channels 3&4). Each of these filters can

be configured independently into one of two

filter types or defeated completely by way of the

three-position “Filter Mode” switches:

“Off”: Defeats the filter completely, allowing

the full range of frequencies present at the

inputs to feed the amplifier. This is useful

for systems utilizing outboard crossovers or

requiring full-range reproduction from one or

both of the A4300’s channel pairs.

“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 both of the A4300’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 both of the A4300’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 A4300 to drive

a subwoofer 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.

JL AUDIO A4300 7

INPUT SECTION

The A4300’s input section allows you to send

signal to the amplifier section through the use of

either two or four differential-balanced inputs.

Input connections are via traditional

RCA-type jacks.

If you wish to send four discrete channels into

the A4300, simply use all four inputs (channels

1 & 2 and channels 3 & 4) and set the “CH 3&4

Input From” switch to “Discrete”.

If you wish to feed all four channels by using

only two channels of input, set the “CH 3&4

Input From” switch to “1&2” and use only the

inputs to channels 1 & 2.

Input Voltage Range:

A wide range of signal input voltages can be

accommodated by the A4300’s input sections

(200mV – 8V). This wide range is split up into

two sub-ranges, accessible via a switch located to

the left of the Input Connectors. Be aware that the

position of this switch will dictate the sensitivity

range for all four input channels.

The “Low” position on the “Input Voltage”

switch selects an input sensitivity range between

200mV and 2V. This means that the “Input

Sens.” rotary control will operate within that

voltage window. If you are using an aftermarket

source unit or an OEM interface processor with

conventional preamp-level outputs, this is most

likely the position that you will use.

The “High” position on the “Input Voltage”

switch selects an input sensitivity range between

800mV and 8V. This is useful for certain high-

output preamp level signals as well as speaker-

level output from source units and

small amplifiers.

To use speaker-level sources, splice the speaker

output wires of the source unit or small amplifier

onto a pair of RCA plugs for each input pair.

No line output converter is needed in most cases.

The output of the amplifier will decrease for

a given input voltage when the “Input Range”

switch is placed in the “High” position.

Conversely, the output will be higher with the

switch in the “Low” position. While this may

sound counter-intuitive, it is consistent with the

descriptions in this section.

INPUT SENSITIVITY CONTROLS

Once the appropriate “Input Voltage” range

has been selected, the controls labeled “Input

Sens.” located in each “Channel Controls”

section can be used to match the source unit’s

output voltage to the input stage of each pair of

amplifier channels for maximum clean output.

Rotating the control clockwise will result in

higher sensitivity (louder for a given input

voltage). Rotating the control counter-clockwise

will result in lower sensitivity (quieter for a given

input voltage.)

To properly set the amplifier for maximum

clean output, please refer to Appendix A (page

14) in this manual. After using this procedure,

you can then adjust any or all “Input Sens.”

levels downward if this is required to achieve the

desired system balance.

6 JL AUDIO A4300

JL Audio A4300 Seite 4

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