8/16/2019 Sören Hjalmarsson - Subwoofer Calibration

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Subwoofer Calibration

Find the optimal crossover frequency, which is usually between 60 to 80 Hz, with the assistance of bass sweeps. These are tones which are set at a uniform level from 00 to ! Hz. "ay attention to

resonances in the area of the crossover frequency #only listen to the sweep throu$h the subwoofer atthis point%.

The positionin$ of the subwoofer has a $reat influence on the standin$ waves or &room modes&. 'corner position is the least favorable in this respect, followed by a position a$ainst a wall. (ou havethe $reatest chance of a uniform sound when the subwoofer is free standin$ in the room.

)n rooms with parallel walls, a virtual partitionin$ of your studio into uniform * by * fields, is afurther assistance in the search for an ideal location. +ivide the room len$th and breath by * andima$ine lines on the floor, or mar these lines out temporarily with mas in$ te-p#see attachment%.

ow you can see on which lines the subwoofer is li ely to cause e/cessive room modes, even when

it is free standin$. Therefore do not place it on any of these lines, least of all on the intersections.

hen you have found a location where the bass sweep of the solo subwoofer sounds uniform in thelistenin$ position, ad-ust the phase position between the subwoofer and the monitor. ow play bac a bass sine tone close to the crossover frequency with the main monitors switched on and rotate the

phase of the subwoofer. The phase position in which the subwoofer sounds the loudest in thelistenin$ position is the correct one.

ow listen to your wonderfully mastered favorite 1d&s at 8!db spl and ad-ust the level of thesubwoofer in such a way that you intuitively $et the ri$ht feel for the bass level. (our monitorsshould sound balanced at 8!db spl in the bass zone.

)f you are dissatisfied with the result, systematically proceed with the measurement microphone andmeasurement equipment to find the ideal location for your sub and to calibrate your monitorin$system.

There are extremely varied ways of proceeding. I shall outline the simplest ones here as anexample:

2. "osition your subwoofer temporarily in your listenin$ position.. "lay bac bass3heavy music and wal around the room. Find the spot in the studio where the

bass sounds best, in the half of the room where the spea ers are located, accordin$ to therules outlined earlier.4. )nstall the subwoofer there.*. 1hec the subwoofer&s phase position. 5end low test si$nals to the monitors includin$ thesubwoofer which are around the crossover frequency at, for e/ample, 60 80 200 Hz andmove the phase switch of the subwoofer bac and forth. The position where the bass soundslouder in the listenin$ position is the correct one.!. "lay pin noise on your monitor setup, includin$ the subwoofer. )nstall a measurementmicrophone in the listenin$ position with the tip facin$ upwards and send the si$nal to a$ood spectrum analyser. ow you can calibrate the level and crossover frequency until theanalyser displays a frequency response which is as linear as possible.

8/16/2019 Sören Hjalmarsson - Subwoofer Calibration

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7oom "artitionin$

#source )nternal 9asterin$ by Friedemann Tischmeyer%