Atlantic Technology SP-8000 Manuel d'instruction - Page 11

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Instruction Manual

to Large the processor/receiver assumes that they can produce full fre-

quency range sound,including very deep bass at fairly high volume levels.

When set to Small it assumes that the speakers are bass limited and feeds

the bass from that channel to the subwoofer. If your processor/receiver

offers this choice,all Atlantic Technology satellite speakers should be set

to Small,regardless of their actual size.

For those of you who may have heard otherwise, the choice of Large or

Small is not a matter of opinion, preference, taste, or based upon the

phases of the moon. So please ignore any and all free and helpful (and

many times incorrect) advice and set them to Small. In fact, the vast

majority of speakers on the market today should be set to small.As a rule

of thumb, if any satellite speaker in your system doesn't have a 10-inch

or larger woofer, it most probably should be set to Small, as far as Bass

Management is concerned.

The PHASE Control

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A subwoofer operating out of phase with the rest of

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the system won't provide optimum low frequency per-

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formance.Also, the correct subwoofer phase can help

compensate for room acoustic anomalies. Therefore,

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a PHASE switch that will alter the phase of the Sub-

woofer is provided on the SP-8000. It has 4 positions (0°,90°,180°,270°)

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for added flexibility.To set the PHASE control, insert the supplied Atlantic

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Technology/Sencore Test and Training CD in your CD/DVD player and select

the broadband bass test tones on Track 16.Have someone sit in the prime

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listening position to evaluate the sound.Pay particular attention to the tran-

sition of bass from the subwoofer to the satellite 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 best not to use a"one note"special effects track like a big

explosion or dinosaur stomping to test the subwoofer.Experiment with the

position of the PHASE control(s) to get the best transition from sub to sat-

ellites. It should be fairly obvious which is the correct setting.In particular,

there will be a smoother, more integrated transition between the satellites

and the subwoofer when they are properly phased.

Parametric Room Equalizer (EQ)

In order to optimize the performance of your subwoofer the parametric

room equalizer should be utilized. The built in Room EQ allows 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. It is designed spe-

cifically to remove (turn down) unwanted peaks in the bass.The proce-

dure is fairly simple: the included Atlantic Technology/Sencore Test and

Training CD is used along with a SPL meter to define the single largest

bass peak at the prime listening position and then reduce it with the

Room 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 the test tones can be used to set the Room EQ "by

ear" we very strongly recommend using a Sound Pressure Level meter or

a Real Time Analyzer to set the Parametric EQ.

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Adjusting the Room EQ Using a Meter or Real

Time Analyzer (RTA)

IMPORTANT NOTE: During all set up operations except setting the

Phase control it will be beneficial to shut off or disconnect all the

speakers except the Subwoofer.

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

before adjusting the parametric room equalizer. Once they're complete,

insert the Atlantic Technology/Sencore Test and Training CD into your

CD or DVD player and go to Track 16, which is a full range test signal

including all bass frequencies from 20Hz to 120Hz. Set the BASS LEVEL

of your SP-8000 for approximately 75dB at the primary listening position.

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

response (Use slow response to allow the meter to average the standing

waves that build up in the room).Continue using Track 16 to observe the

overall response of the subwoofer. It is highly likely that you will find at

least one significant peak (between 20Hz and the crossover point set on

the amplifier or in the processor).Write down the center frequency of the

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

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

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FREQUENCY

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125

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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

SA-700

frequency.For example,if the chosen frequency is 40Hz,1 octave higher

Servo Controlled

would be 80Hz,and one octave lower would be 20Hz.Since the WIDTH

Subwoofer Amplifier

control ranges from 0.2 octave to 1.5 octaves you see that you can adjust

from a fairly narrow band to a fairly wide band on either side of the center

frequency.Next,set theATTENUATION control to the approximate minus

dB value to compensate for the peak. Measure the bass response again

and see how much you have reduced the overall peak.You may need to

fine-tune the controls to smooth the response as much as possible.

Setting the Parametric EQ Using an SPL Meter

If you only have an SPL meter, set the meter to C Weighting and Slow

response. Set the Bass Level of your SP-8000 for approximately 75dB at

the listening position as outlined above using Track 16 of the test disc.

Sit in the prime listening position with a pencil and paper. Play Tracks

1-15 sequentially to measure the subwoofer response.Take enough time

with each measurement to allow the meter to stabilize.Write down the

measured level for each frequency, covering the range from 20Hz to the

crossover point selected on the subwoofer amplifier or in the receiver/

processor. Once again, you will most likely find one or more significant

peaks in the bass response.Proceed as detailed above to reduce the larg-

est peak as much as possible.

octave resolution and slow

Begin setting the para-

WIDTH

ATTENUATION

metric EQ by adjusting

1.0

-10

the FREQUENCY control

to the approximate center

0.2

1.5

-20

0db

frequency of the peak.Next

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adjust the WIDTH control

Setup