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Latest Tech Helps Audio Engineers Dial Down Sound Problems

As technology makes it easier to pack more channels of audio into the production stream, new devices are helping producers manipulate digital audio signals to produce a crisp sound track while keeping it in synch with the video images.

As technology makes it easier to pack more channels of audio into the production stream, new devices are helping producers manipulate digital audio signals to produce a crisp sound track while keeping it in synch with the video images.

Today, almost everything is recorded in a digital audio format, specifically the signal is encoded in digital form rather than in an analog form. Sound is passed through an analog-to-digital converter and pulse-code modulation typically is used to encode it as a digital signal. However, as the new technology has enabled government video producers to squeeze more channels into their productions, it has created significant problems, such as synchronization (which makes sure that the sound matches what is on the screen) as well as proper channel allocation, volume and balancing.


Harris’ VTM Series Harris Broadcast makes a range of audio monitoring devices that can improve a final project, said Paul Keller, the company’s product manager of Videotek Test & Measurement. With all of the high-tech audio currently being used, it is almost impossible to produce anything without a good audio monitor.

“It would be like driving a car with no instruments on the dashboard,” Keller said. “You don’t know how fast you are going and you don’t have any gauges. You can get along that way for a while, but eventually you will get caught speeding or break down. With audio you really need something to guide production,” he said.

A lot of audio and video equipment has built-in monitors for audio signals, but many built-in systems do not provide a level of control sufficiently fine for a top-notch production, Keller said. Harris’ VTM Series of multiformat on-screen monitors are popular. Cost-effective, they can measure HD/SD SDI, ASI and PAL/NTSC analog composite or component video, or Dolby E and Dolby Digital audio. The VTM 4100 is used widely because it is customizable, including just the features that a producer needs for their work, he added.

Videotek CMN-91 Another device well fitted for government producers is the Videotek Compact Monitor Series. Small and portable, the CMN-91 tests signal quality across all DTV formats up to three gigabytes. It possesses two SDI inputs and provides selectable waveform, vector, gamut, timing and picture full-screen display. The CMN-91 can meter all 16 channels of embedded audio or one AES input, Keller said. Their size and portability make them suitable for fieldwork where most government training video is shot.


Producers may also be interested in two versions of Leader Instruments Corp.’s new portable audio monitors, the LV5838 and the LV5837.

Leader Instruments Corp.’s LV5838 and LV5837 They share such common features as level meters, surround sound, loudness measurement, Dolby, status display and error log functions. The LV5837 can process up to 16 channels of discrete AES/EBU audio inputs.

The LV5838 includes all features of the LV5837, plus it supports of 3G/HD/SD-SDI embedded audio and 16 channels of AES/EBU inputs or outputs, the company said.


Tektronix’s WVR7200 Tektronix offers a range of waveform monitor (WFMstandalone products) and waveform rasterizers (WVR- are rack-mounted units) for measuring and monitoring the real-time performance of video and audio. For example, the WVR7200 provides a monitoring tool set for optimum sound quality. Loudness monitoring ensures consistent audio loudness levels between programs and commercials. Sixteen channels of embedded audio levels can be monitored, as well as Dolby audio.

Tektronix’ WVR8200 and WVR8300 Waveform Rasterizers are better suited for multi-format environments, providing flexible options and field-installable upgrade kits to monitor diverse video and composite analog video. Both come with Dual Link SDI (which meets Society of Motion Picture and Television Engineers standard 372M), compliant monitoring, automatic format detection (SMPTE 352M) and selectable display.


Volicon’s Observer Transport Stream screen shot Massachusetts-based Volicon produces the Observer Transport Stream loudness monitoring system that broadcasters can use for content monitoring, troubleshooting, resolution and regulatory proof of conformance, said Andrew Sachs, the company’s vice president of product management. Agencies also use the system as a sort of electronic clipping service, Sachs said.

“What a lot of government agencies and police departments do is use it for media monitoring,” Sachs said. “The local police may want to be alerted if they are mentioned in media. They want to know if there is something that they should be prepared for and get ahead of an issue.”


Ward-Beck Systems’ AMS8-1 Ward-Beck Systems offers a range of digital audio monitors, including the rack-mounted AMS8-1 and AMS16. The AMS8-1 handles and displays (using LCD bar meters) four AES digital audio inputs (eight channels), while the AMS16 handles/displays eight AES digital audio inputs (16 channels).

Ward-Beck Systems’ AMS16 Ward-Beck is set to launch a multichannel audio digital interface monitor called the 32 ME, said Eugene Johnson, managing director of Ward- Beck Systems.

MADI originally was designed to allow multiple AES audio channels to be multiplexed onto a single cable and transported between an audio console and a digital audio workstation, Johnson said. MADI is becoming more popular with large television stations and mobile applications because it is a costefficient method to transport up to 64 channels of AES digital audio over a single cable. Normal video can only support 16 channels of embedded audio on a single cable and MADI increases that number four-fold, Johnson said.

“The problem faced in the field is that you need an expensive console or a DAW with MADI capabilities to de-multiplex the audio in order to monitor it, meter it and separate the channels,” Johnson said. “The 32ME is a cost-effective device that performs these three functions and can be deployed anywhere along the signal path to ensure that the correct signals arrive at the final destination.”

It also has a headset jack to listen to the audio and provides a two-channel monitor output that can be connected to a rack-mount speaker system, Johnson said. The 64 decoded AES channels will also be available on the rear panel on DB-25 connectors, he added.


Wohler Technologies’ AMP1-16M Wohler Technologies also has a range of audio-monitoring systems, covering from two to 16 channels with its top-end AMP2-16V Series supporting 16 channels of embedded audio, multi-rate 3G/HD/SD-SDI, AES, or analog audio inputs and outputs audio monitoring with Dolby D/E/DD+ decoding capability encased in a chassis that occupies two rack units. Synchronization is still an issue, but many of the new monitoring systems have dramatically reduced such concerns, said Martin Winsemius, a company engineer.

Wohler Technologies’ AMP2-16V Wohler’s latest product is the AMP1-16M, a device for monitoring only serial digital interface audio, Winsemius said. It provides instantaneous selection and summing of any grouping of SDI audio pairs, features adjustable volume and balance controls, clear display of levels with configurations that can be created, saved and recalled via Ethernet connection using an intuitive PC interface, he said.

“By keeping everything small sized and omitting extra inputs, it is a really handy and easy-to-use device,” Winsemius said. “This is something that agencies can use for training video. It brings the whole cost into a lower price range and it’s easy to work with.”


Harris Broadcast:

Leader Instruments Corp.:



Ward-Beck Systems:

Wohler Technologies: