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GENERAL GUIDELINES FOR USE
The sound energy in each of the ten octave bands is shown simultaneously and continuously - that is RTA or Real
Time Analysis. Many tests are most easily run using a pink noise source (Gold Line model PN2) which puts out
equal energy across each filter band. If it is fed directly to the unit the result will be a straight-line display. With
the pink noise fed through a sound system, any deviations from flat response will be shown on the analyzer. The
accuracy of a reading with pink noise will be improved by mentally averaging any level variations noted. Point the
analyzer at the speakers keeping it away from the body for best accuracy. If outside, or the room permits, keep at
least 20 ft. away at 31.5Hz, 10 ft. away at 63Hz, etc. Room effects may prevent following these guidelines. For
actual SPLs, switch the ASA10B to C/SPL, or A/SPL for levels in dBC or dBA weighting.
SOUND SYSTEM EQUALIZATION: Because the ASA10B has it's own built-in microphone, you can measure
the sound output from any type of sound source. The response will be shown in the ten filter-band display whether
the tests are made in a room, at a club, or even outdoors. The microphone of the ASA10B is positioned clear of the
end of the analyzer case to minimize shielding effects. The ½ inch microphone diameter of the ASA10B facilitates
checking SPL calibration with an acoustical calibrator. The ASA10B has been calibrated by the factory - but can be
field calibrated.
1. Turn off the sound system before making connections, and put all tone controls, EQ etc., to their flat positions.
Set volume to zero.
2. Connect the noise source to a line level input to one channel only.
3. Turn the amplifier system on.
4. Advance the volume to a medium-high sound level. Do not overdrive.
5. Set the ASA10B to SLOW decay time with low gain and turn it on.
6. Take a position in the center of the listening area.
7. Increase the gain of the analyzer to put the majority of the filter band responses near 0dB. Make certain the unit
is pointed at the speaker. Take note of the levels in each of the octaves.
8. In the lowest bands there can be great deviations from flat response caused by speaker and room characteristics.
Usually it is impossible to make the changes in room shape and size that might be desirable, but changes in
speaker position are usually quite feasible.
9. If inside, try different speaker positions along and up and down the back wall, and also try various distances
from the wall. Use the combination that gives the best result, i.e., the flattest response, especially at the low-
frequency end. Move around in the listening area to see if there are measurable room effects appearing in the
lowest filters. Make certain the sound level from the system is high enough to cover over the normal room ambient
noise.
10. The high-frequency response of the system will be greatly affected by the speaker's angular positioning-how it
is pointed back and forth and also up or down. Make such adjustments as necessary for maximum output in the
highest frequencies.
11. After completion of the above two steps, move around in the listening area while observing the analyzer
display. Take note of any large shifts in the response. Use the HOLD function to make comparisons.
12. Adjust the systems equalizers, tone and tweeter controls, etc., to obtain the flattest response in the listening
area. Do not try to boost out deep notches in the response, such as might be caused by a poor crossover. In general,
limit the amount of boost used in order to prevent overdriving amplifiers and speakers. Do use cut to bring down
peaky areas. To the extent possible, use tone controls or other broad, shelving-type EQ to minimize the need and
extent of narrow-band EQ.
13. Recheck system response with the analyzer, and trim adjustments for the best compromises over all the bands
and all-important listening areas.
14. Repeat steps 6 to 13 for the other channels.
15. With both channels driven equally (balance control centered) touch up low frequency EQ for flat performance
up to 250Hz.
16. The liveliness of a room will have an effect on the system response, primarily in the medium and high
frequencies. Rugs, stuffed furniture, drapes and people are all absorbers of sound, and acoustically dead rooms
require more sound from the speakers, with a need for more boost of medium/ high frequencies.
17. CAUTION: Do not use extreme amounts of bass boost with small speakers. Destruction could be the result.
Try to find the best speaker to wall distance to minimize the need for the boost.
