Tools Required
J 39916-A CD and Cassette Diagnostic Audio Kit
Important: Always compare the front speakers to the front, and the rear speakers to the rear. Do not compare the front speaker to the rear speaker. The speakers may be different. The speakers mounting environment may cause the speakers to sound different.
Tones are used in order to test and evaluate coaxial speakers or other complex speaker systems.
The following list indicates the 3 basic tones that are used:
| • | The 50 Hz sine tone |
| • | The 500 Hz warble tone |
| • | The 9 kHz spectral tone |
The combination tone is a blend of the above 3 tones.
Bass/Sub-Woofer Test (50 Hz Sine Tone)
The 50 Hz sine tone is used in order to evaluate the bass response of an audio system. This tone is also helpful in evaluating audio systems that have separate sub-woofer amplifiers and speakers.
Midrange Speaker Test (500 Hz Warble Tone)
The 500 Hz warble tone is used in order to evaluate the midrange speaker response. This tone has different audio characteristics than a sine tone. This tone produces a warble sound. At the midrange frequencies, it is better to use a warble tone than a sine tone because the location of a warble tone source, such as a speaker, is easier to identify. A normal sine tone may set up a standing wave within a vehicle which makes it difficult to determine the source location.
Tweeter Test (9 kHz Spectral Tone)
The 9 kHz spectral tone is used for tweeter or high frequency evaluation. This tone is a section of frequencies of equal amplitudes that ranges from 8.5 kHz to 9.5 kHz. This sounds like a group of crickets chirping.
The spectral tone is used for the following 2 reasons:
| • | Easier to locate the source, much like the warble tone |
| • | Easier to identify for those people with high-end hearing loss problems |
All Speaker Test
The combination tone may be used for the following numerous audio conditions:
| • | Distorted sound from the speakers |
| • | No sound from the speakers |
Comparative AC voltage measurements may be made on the speaker terminals. The fade and the balance controls must be in the detent position, when using the combination tone. A determination may be made in the diagnosis of the speaker or the amplifier with these voltage measurements.
Speaker/Grille Rattle Test (50 Hz to 8 kHz Swept Sine)
The next portion of the tape may be used in order to diagnose the following conditions:
| • | Speaker rattles |
| • | Grille rattles |
The first test is 2 tones played back to back. The second test is a variable frequency tone. The frequency change is at a much slower rate. You may use both tests in order to repair a speaker rattle or buzz. If the problem has already been isolated, the fade and the balance controls may be set to the proper location and the test tones may be played in the specific problem area.
