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1. Four Golden Rules 1. What four Golden Goals are needed when designing a sound system for a vehicle?
2. Using Ohm’s Law Calculate the impedance of the following speaker connections : (3) 2.1 • Two 4-ohm speakers connected in parallel ? (Show Calculation)
2.2 • two 4-ohm speakers connected in series? (Show Calculation)
2.3 • Three 4 ohm speakers in parallel? (Show Calculation)
3. Using Ohm’s Law , calculate the nominal impedance that a stereo amplifier would see in bridged mode, using a pair of 2 ohm woofers connected in series? (Show Calculation) (2)
4. When designing a sound system list the priority order of components. (5)
5. If a single woofer is playing in a 3 cubic foot enclosure resonating at 55 Hz, what size would it need to be if the same model woofer was added to the first woofer in an isobaric configuration also resonating at 55HZ? (2) Please draw a picture of an Isobaric configuration (1) 5.2 • Draw on a piece of paper and upload it.
6. What test instrument is used to establish what frequencies are present on a multichannel factory source? (2)
7. If a vehicle has limited electrical capacity, name two Acoustic Improvements that can be done to limit the demand and increase the performance? (4)
8. Name 4 Types of filters found in the X-Over of a DSR1 (8)
9. List the two components required to build a passive crossover and state the terms used for their rating? (Abbreviations accepted) (4)
10. What frequency is equal to road noise in a vehicle? (1)
11. Does Rockford Fosgate products have a solution to counter road noise? If so what is it called? (2)
12. Draw 3 different types of woofer enclosures and name 2 advantages and 2 disadvantages of each. 1 bonus point given for all correct Answers? (9+1) 12.1 • First Enclosure: Draw on a piece of paper and upload it. 12.1 • Please list Two advantages
12.1 • Please list Two disadvantages
12.2 • Second Enclosure: Draw on a piece of paper and upload it. 12.2.1 • Please list Two advantages
12.2.2 • Please list Two disadvantages
12.3 • Third Enclosure: Draw on a piece of paper and upload it. 12.3.1 • Please list Two advantages
12.3.2 • Please list Two disadvantages
13. Given a rectangular box with external dimensions of 50cm high, 30cm deep and 50cm wide, material thickness of 1.6cm, calculate the internal volume In litres. 1 Bonus point will be given per cubic feet value? (3+1)
14. Name one method to verify the tuning frequency of a ported enclosure. (1)
15. When installing a vented enclosure in a Bakkie, given the space limitations Which is the most efficient port to use (Slot, Rectangular or Round) and where would it be best located, closest or futherest from the driver of the vehicle?
16. Name 3 elements that can affect or influence the tuning of a ported enclosure? (3)
17. Define the 3 steps required for running in a sub-woofer? (3)
18. What tool is necessary to evaluate a vehicles electrical system? (2)
19. At which end of the audio chain do we start at looking for line noise, And if found mention one method of curing it? (2)
20. Besides testing SPL, name two uses for the DM-RTA Real Time Analyser? (4)
21. What test tone is used to test the source units output response curve? (1)
22. Name two uses for when using an IM-SG? (2)
23. What is the speed of sound at 22 C° ? And how can this affect a speaker in a car door? (2)
24. If an amplifier is rated at 100 watts RMS, what number (factor) do you use to determine the peak power of the amplifier?
25. List two benefits when using a CC1? (2)
26. List one installation fault that could result in a burnt coil on a speaker? And one component that would prevent damage to a tweeter. (4)
27. What is the method called for determining the optimum cabin gain signature of a vehicle? (2)
28. What is another name for speaker electrostatics and which instrument can provide this information if you do not have them available? (2)
29. When setting up a vehicles audio system, name 3 test tools that are minimally required.
30. Name two devices that can be used for OEM integration? (2)
31. If an amplifier is producing 10volts AC into a 4 ohm speaker, how many Watts, is it producing? (Show calculation) (4)
32. What frequency are our ears most sensitive to. And by how many DB's. (2)
33. How many DB’s louder must a system play for a human to perceive as double? (2)
34. Name five features of Term Pro? (5) 34. • Please list these features
35. Give two benefits that a DD 1 provides? (4) 35. • Please list Two benefits
36. What type of crossover is used on a Full Chasis Power amplifier and at what slope? (4)
37. What is the most powerful tool one can develop in car audio ? (1)
38. What is the upper and lower frequencies of a single octave at 100hz (1)
39. A filter that removes high frequencies as known as a.....pass filter? (1)
40. List two x-overs slope types and DB's associated with the filters listed in question 39 above (2)
True or False 41. The Perfect tune app to control the dsr1 can be found on the Microsoft app store (1) 42. When using an IM-SIG is the impedance of a speaker in an enclosure is lowest the resonant frequency of the speaker – give a reason for your answer (2) 43. Any speaker that is not connected to a source, will not produce any impedance reading if the cone is manually moved up and down – give a reason for your answer (2) 44. RF power amplifiers make use of patented technology knows as constant power to compensate for impedence variances – give a reason for your answer (2) 45. The dsr1 cannot correct any phase related issues at the listening position? - give a reason for your answer (2)
In your own words 46. Briefly explain time alignment. (1)
47. Briefly explain speakers playing out of phase. (1)
48. What is the ideal crossover frequency to set a front stage both (low and high) ? How much of power is required to generate a gain of 3db? (2)
49. What is the difference between a balanced and unbalanced line input Does the DMRTA and epicentre have balanced, unbalanced, both or no inputs. In your own words. (2)
50. How does changing the Q factor affect neighbouring frequencies around a selected frequency (e.g., 100 Hz)? (1)
51. What is the purpose of a infrasonic filter and when should it be used (2)
52. How many DB's down and from which frequency should the infrasonic filter be used? (2)
53. Scenario: You have a 2 channel stereo amplifier and three speakers. The coil configuration are as follows. (4)
End of test. Please review your answers and tap Submit to submit your responses. 