Atlantic Technology SA-350 사용 설명서 - 페이지 13

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Instruction Manual

ing position to evaluate the sound. Pay particular attention to the deep

bass as well as the transition of bass from the subwoofer to the satel-

lite speakers. You can also listen to a musical source such as a CD or

DVD, with strong bass content that spans the range from deep bass

to mid bass (a well recorded jazz disc with someone playing a full

stand up bass is always a good choice). It's usually best not to use a

"one note" special effects track like a big explosion or dinosaur stomp-

ing to test the subwoofer. Experiment with the position of the PHASE

control(s) to get the most extended bass and the best transition from

sub to satellites. It should be obvious which is the correct setting. In

particular, there will be a smoother more integrated transition be-

tween the satellites and the subwoofer when they are properly phased.

Parametric Room Equalizer (EQ)

In order to optimize the performance of your InWall subwoofer the

Parametric Equalizer should be utilized. The built in Parametric

EQ(s) allow you to select the frequency you want to adjust, and how

wide a band on either side of that frequency you're going to adjust

with it. They are designed specifically to remove (turn down) un-

wanted peaks in the bass. The procedure is fairly simple: the in-

cluded Atlantic Technology/Sencore Test and Training CD is used

along with a meter to define the single largest bass peak at the prime

listening position and then reduce it with the Parametric EQ.

The test and setup CD also includes a wealth of general information

concerning sound reproduction and home theater, in addition to

the test tones. Although one set of tones is intended for setting the EQ

"by ear" we very strongly recommend using a Sound Pressure Level

(SPL) meter or a Real Time Analyzer to set the Parametric EQ.

Adjusting the Parametric EQ Using a Meter

or Real Time Analyzer (RTA)

It's important to complete all the preceding steps regarding speaker

setup before setting the parametric equalizer. Once they are com-

plete, insert the Atlantic Technology/Sencore Test and Training CD

into your CD or DVD player and go to Track 22, which contains bass

frequencies from 20Hz to 120Hz. Set the BASS LEVEL of a single

subwoofer channel to 75dB at the primary listening position. If you

are using an RTA, set it to at least 1/6

response. Continue using Track 22 and measure the response of the

sub using at least a 1/6

octave resolution (Use slow response to

allow the meter to average the standing waves that build up in the

room). Chances are that you will find at least one significant peak

in the subwoofer's range (between 20Hz and the crossover point set

on the sub or in the processor). Write down the center frequency of

the peak, how "wide" the peak is (by noting the upper and lower

frequencies where it starts and stops) and how high it is, in dB.

Begin setting the Parametric EQ by adjusting the FREQUENCY con-

trol to the approximate center frequency of the peak. Next adjust

the WIDTH control to the approximate width of the peak. Note that

the WIDTH control is calibrated in octaves. An octave is a doubling

or halving of any chosen frequency. For example, if the chosen fre-

octave resolution and slow

band on either side of the center frequency, depending upon how

wide the peak is. Next, set the ATTENUATION control to the ap-

proximate –dB value to compensate for the peak. Measure the bass

response again and see if you have significantly reduced the overall

peak. You may need to fine tune any or all of the controls to smooth

the response as much as possible.

Level Setting Using an SPL Meter

If you only have an SPL meter, set the meter to "C" weighting and

"Slow" response then use Track 22 to set the BASS LEVEL to 75dB.

Next use Tracks 1-21 sequentially to measure the subwoofer re-

sponse. Take enough time with each measurement to allow the meter

to stabilize. Write down the measured level for each frequency, cov-

ering the range from 20Hz to the crossover point selected on the

subwoofer amplifier or in the receiver/processor. After you have de-

fined the peak, proceed as outlined above to reduce it.

When setting up a complete home theater we strongly recommend

that you use a Sound Pressure Level meter. At the time of this writ-

ing Radio Shack® has one that is very affordably priced (approxi-

mately $40) and works well. However, for the best result in setting

up the levels and the parametric EQ you would be much better served

by using a true audio test instrument with a Real Time Acoustic

Analyzer (RTA) like the Sencore® SP 295.

To use an SPL meter, turn on your system, put the Processor/Re-

ceiver in the Test Mode and set its main volume control to a moder-

ate volume level. If the volume control has a 0dB setting with minus

dB below and plus dB above 0, set the control to 0dB. Next, sit in the

prime listening position, set the SPL meter to the 70dB scale, Slow

Response, and C Weighting. Now, holding the meter pointed up and

in front of you, let the system cycle its test tone from speaker to

speaker. Check the meter and set every speaker (including the

subwoofer), to 75dB using the individual level settings in the Pro-

cessor/Receiver. You may have to use the Processor/Receiver's main

volume control to get the left front speaker to 75 dB but from then

on use the receiver's internal level adjustments. These are almost

always accessible through the Processor/Receiver's remote control.

As tempting as it may be to set the subwoofer and/or surround

speakers higher than 75dB, set them to 75dB and see if you can ac-

climate to it. Try watching several different movies and keep in mind

that the goal is to have a system that sounds like you're actually "in

the movie. " In most cases, you shouldn't be consciously aware of the

surround output at all.

Operation

quency is 40Hz, 1 octave

higher would be 80Hz,

and one octave lower

would be 20Hz. Since the

WIDTH control ranges

from 0.2 octave to 1.5 oc-

taves you see that you can

adjust a from a fairly nar-

row band to a fairly wide