Assignment - Audio connectivity and interface techniques

General guidance- Centres should ensure that learners have the required soldering skills to construct the interfaces in this assignment.

Task Ai

Tutors should draw upon their knowledge of the signal flow into, through and out of the console to inform their teaching of this unit.  They should enable learners to systematically evaluate and access convenient points to inject test signals and to monitor signal levels. . Monitoring and signal injection can be done through patch points, measuring signals at plugs and utilising pre/post sends. The console manual should provide valuable information on signal flow and types of signal present throughout the system. 

Learners findings should be presented as a labelled block diagram of the system.

This block diagram should be consulted during the practical faultfinding exercise. A systematic and logical approach should be used in finding the source of the fault

Task Aii

The audio system fault will have been created by the assessor through disconnecting a part of the signal chain; by removing a connector or by using an open circuit lead.

Task B

The tutor is responsible for providing the components for this task (eg transformers etc) and to create suitable interfaces between the two systems.

Tutors should be able to demonstrate the wiring systems and signal levels used in professional and consumer systems and ways of interconnecting the two.

Tasks

Background information - This assignment allows learners to demonstrate their knowledge and practical ability in connecting together analogue and digital systems. Learners will demonstrate basic fault finding skills on an analogue system. 

Task Ai - Produce a block diagram and notes-

Learners are required to measure and note down the signal levels throughout a recording system by using a test tone at the input that produces an output level of "0 Vu" (PPM 5) at the output sockets feeding the multitrack recorder. 

The signal chain should cover the signal source through to the multitrack input and the multitrack output back to monitoring section. 

Use of the patch bay and access to in/out connectors should be used to measure these levels throughout the signal chain. Each point in the system should be assessed as to whether it is balanced or unbalanced. 

Learners should present this information as a block diagram.

Learners should make notes showing how these points may be used in the process of fault finding either by injecting a test signal or by signal monitoring and measurement.

Task Aii - Locate a fault

Learners are required to determine the position of a fault in a signal chain using the techniques indicated in task Ai above. Learners should use logical and efficient processes to locate the fault.

Task B - Implement interfacing, produce a diagram and notes

Learners are required to carry out the interfacing of both:

• an unbalanced consumer level input of a device from a balanced professional level desk output
• an unbalanced consumer level output of a device to a balanced professional level desk input.

Learners should produce a tested interface and submit the following:

• a signal flow diagram
• notes of calculations
• an explanation of the earthing use
• an explanation of the differences between professional and consumer systems
• a brief test report.

Task Ci - Produce a report

Learners are required to produce a report explaining the fundamental processes and operation of the following digital audio signal chain with master word-clock:

20 bit analogue to digital converter comprising anti-alias filter (AAF), dither generator, sample and hold and quantiser

AES interface with manual selection of channel status

20 bit digital to analogue converter including reconstruction filter

master word-clock.

Task Cii - Implement and construct a cable

Learners are required to implement and construct a cable to convert between an AES digital output to SPDIF digital input.

Learners should demonstrate the correct operation of the interface and produce notes describing the operation of the interface. They should also produce any relevant calculations and describe limitations in the use of channel status information that is transferred.