Tuesday, December 22, 2015

INFINITY IL60 L/R Powered Loudspeaker Test procedure


Equipment needed:
# Function/signal generator/sweep generator
# Integrated Amplifier
# Multimeter
# Speaker cables
General Unit Function (UUT = Unit Under Test)
Switches on the amplifier faceplate:
Sub Input to “Line Level”
Low Pass Filter to OFF
Bass Optimization system to OFF
1. From the signal generator, connect one line level (RCA) cable to the IL60 Line Level Input jack on the UUT.
2. On the front of the unit, turn the LEVEL control full counterclockwise (1).
3. Turn on generator, adjust to 100mV, 40 Hz.
4. Plug in UUT; turn the power switch ON. LED should be Red. Turn LEVEL control full clockwise (10).
5. LED should now be Green; immediate bass response should be heard and felt from rear port tube opening.
6. Turn off generator, turn LEVEL control fully counterclockwise (1), disconnect RCA cable.
7. Connect one pair of speaker cables to Speaker Level input terminal on UUT. Cables should be connected to an integrated amplifier fed by the signal generator.
8. Switch Sub Input on the amplifier faceplate to “Speaker”.
9. Turn on generator and adjust so that speaker level input at the amplifier is 1.5V, 50 Hz. Turn LEVEL control full clockwise (10).
10. Green LED should light, immediate bass response should be heard and felt from the port tube opening.
Sweep Function
1. Follow steps 7-10 above, using a sweep generator as a signal source.
2. Sweep generator from 20Hz to 20kHz. Listen to the cabinet and drivers for any rattles, clicks, buzzes or any other noises. If any unusual noises are heard, remove woofer and test.
Driver Function (Woofer)
1. Remove woofer from cabinet; detach + and - wire clips.
2. Check DC resistance of woofer; it should be 3.4 ohms ±10%.
3. Connect a pair of speaker cables to driver terminals. Cables should be connected to an integrated amplifier fed by a signal generator. Turn on generator and adjust so that speaker level output is 5.0V.
4. Sweep generator from 20Hz to 1kHz. Listen to driver for any rubbing, buzzing, or other unusual noises.
Bass Optimization System
NOTE:It is important that you make the same adjustments to both loudspeakers. Set the Bass Optimization System Bandwidth adjustments to a middle position (10 clicks from a fully clockwise position) and set Level adjustments for a –6dB (8 clicks from a fully clockwise position). Then,while the music is playing,sit in your favorite chair and have somebody else slowly adjust the Frequency controls from fully clockwise to fully counter-clockwise. At a certain frequency, you should hear the problem lessen and the overall bass performance improve. When you are satisfied that you have found the best frequency, have your assistant vary the Levels slowly up and down until you have maximized the improvement.If you have really keen ears, you can also have the Bandwidth controls adjusted for maximum benefit. While the Bass Optimization System allows the listener to fine-tune the bass response to sound best in a particular room,some listeners don’t have the skill or desire to adjust their system by ear. In order to facilitate quicker and more accurate results, Infinity has developed an optional test and measurement kit that allows the user to perform a series of measurements and aids him/her in properly setting the Bass Optimization System controls. With the addition of this kit,the Bass Optimization System becomes truly room-adaptive. The kit consists of the following:a test CD, a sound-level meter that is specifically calibrated for low frequencies, and something we call a “Q-Finder, ”a device to help find the width of the measured curve and, finally, a measurement template. It works as follows. The listener plays the tones from the test CD and records the relative output level of each test tone, using the sound-level meter, on the provided measurement template. After all the tones are complete, the template contains a response curve for the frequencies below 100Hz. The user simply notes the frequency of the largest bass peak,calculates the correct amount of attenuation,and uses the “Q-Finder” to determine the width of the curve. These three values are dialed into the Bass Optimization System controls located on the speaker.The entire process takes less than twenty minutes.