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SP-8000 Subwoofer Preamplier
11
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
A subwoofer operating out of phase with the rest of
the system won’t provide optimum low frequency per-
formance. Also, the correct subwoofer phase can help
compensate for room acoustic anomalies. Therefore,
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°)
for added exibility. To set the PHASE control, insert the supplied Atlantic
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
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-
cically 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 dene 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.
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 benecial 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
th
octave resolution and slow
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 nd at
least one signicant peak (between 20Hz and the crossover point set on
the amplier 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 large it is, in dB.
Begin setting the para-
metric EQ by adjusting
the FREQUENCY control
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 frequency 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 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 the ATTENUATION 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
ne-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 amplier or in the receiver/
processor. Once again, you will most likely nd one or more signicant
peaks in the bass response. Proceed as detailed above to reduce the larg-
est peak as much as possible.
Setup
SA-700
Servo Controlled
Subwoofer Amplifier
Atlantic Technology
®
I
NNOVATIVE
H
OME
T
HEATER
ATTENUATION
75 1.0
25 125 1.50.2 -20
FREQUENCY
WIDTH
-10
0db