JBL SDEC-3000 Setting Output Level, Digital SLM Instructions, Setting Levels before Calibrating

9 Setting Output Level

9.1 Setting Levels before Calibrating

Using the internal noise generator of the SDP set all outputs to achieve 75dB using the “C” weighting and “SLOW” response. This will maintain the best signal to noise and headroom possible by optimizing the gain structure of the system.

9.2 Final Level Set after Calibrating

Setting the final output level should be done after all corrective EQ has been completed. It is very important that this be done so that all channels have a good balance and are properly calibrated for the average output in the mid-band frequencies. Use the internal noise test from the SDP and test one channel at a time.

•Set main and surround channels to 75db.

•Set the subwoofer channel to average between 82dB- 85dB.

9.2.1Level Matching Multiple Surround

and Subwoofer Channels

The SDEC-4000 has multiple outputs for Subwoofers and Side Surrounds. These will need to be level matched to each other before final output levels are set.

1.Using the internal noise test of the SDP test each output individually. It will be necessary to mute the output you are not testing. Make sure the Trim Link is off (not RED).

2.Once you have set each to the reference level of 75dB enable the Trim Link feature so that the led turns RED.

3.With all the multiple channels un-muted test together and adjust the output to reach the same reference level. You will now have an output that has all the multiple channels level matched and the overall output set to the reference level. Follow the instructions for level matching the multiple surrounds and subwoofer channels first and then set the overall output level to the following reference level.

9.3 Using the SPL Meter

9.3.1Analog SLM Instructions

NOTE: All instruments of this type are most accurate when operated in the upper end of the selected range. You should always use the lowest RANGE setting possible. For example, if you are balancing a system using the Surround Processor's noise generator (75dB) you would set the RANGE selector to 70dB.

1.Rotate the RANGE Selector clockwise one click to the BATTERY TEST position. Observe the meter indication. A reading anywhere within the red BATT TEST range indicates adequate battery power. If the indication is below this range, replace the battery before using the instrument.

2.Now rotate the RANGE Selector clockwise to the desired range. The meter has a display range from -10dB to +6dB. The 0dB point corresponds to the RANGE selected. Therefore, if the 80dB RANGE is selected, a 0dB reading will equal 80dB.

3.Slide the WEIGHTING Selector to "C" weighting for channel balance tests. "A" weighting cuts low frequencies. This will cause errors when measuring subwoofers.

4.It is recommended that you slide the RESPONSE Selector to the SLOW position. This slows the meters response to sudden changes in sound level which can make average level readings difficult.

9.3.2Digital SLM Instructions

NOTE: All instruments of this type are most accurate when operated in the upper end of the selected range. You should always use the lowest RANGE setting possible. For example, if you are balancing a system using the Surround Processor's noise generator (75dB) you would set the RANGE selector to 70dB. In the event you have selected a range that is too low, an OVER-RANGEcondition is indicated by a flashing display. Select the next higher range.

1.Turn the SLM on by rotating the RANGE Selector clockwise. Continue to rotate the RANGE Selector to the desired RANGE.

2.Press the WEIGHTING button to select "C" weighting for channel balance tests.

3.It is recommended that you slide the RESPONSE Selector to the SLOW position. This slows the meters response to sudden changes in sound level which can make average level readings difficult.

4.Check the display for a low battery indication. If the battery needs replacing, BATT will appear in the upper left-hand corner of the LCD display. Replace the battery if necessary.

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SDEC -X000 DACS Calibration Manual v1.0.doc