29 Feb 2016

The truth, the whole truth, and nothing but the truth.

Melbourne’s new $230 million City West police station in Docklands houses nearly 1,500 staff, united from multiple locations and divisions. With over 240 rooms fitted out with audio visual equipment, the facility boasts everything from a simple screen with automated control in the lunch room to a 28 screen video wall in the main operation centre that can display 16 individual sources at once. The building is also the new home of the Forensic Audio Unit, who are tasked with analysis and enhancement of audio recordings to solve and prevent crimes.

Ry Wilton, Audio Visual Commissioning Technician at Programmed Electrical Technology headed up the installation team, making the Police’s AV design a reality. Part of that was delivering a reference-quality monitoring solution for their main forensic audio studio, which was built to exacting standards. “Everything had to be soundproofed,” reports Ry. “The walls were up to 285mm thick with alternating layers of wood and metal so the studio was also immune to radio interference. We had to get all of our cabling and services in before the walls went up, or we wouldn’t have gotten through. They’ve installed a mixing desk that routes all their sources; computers, DVD, CD and proprietary recorders. They can play any format of audio. The studio is an audiophile’s dream! For monitoring, they needed something that could be both extremely loud but also crystal clear.”

The Forensic Audio Unit is tasked with enhancement and analysis of a wide variety of sources, including speech and ambient sound. Their monitoring solution must provide the most accurate reproduction possible, with no colour or artefacts added. Having used and loved their legendary, 1980s era JBL 4430 studio monitors at their old facility in Macleod, the audio team had come to trust and respect the JBL brand. In choosing new monitors for City West, they decided to step forward into the future while keeping part of their heritage, and chose a pair of JBLs flagship M2 Master Reference monitors, powered by a Crown I-Tech 4x3500HD power amp.

With no less than five new patents in their 2216Nd Differential Drive Woofer, and one each for the D2 Dual HF Driver, Image Control Waveguide, and Bass Reflex Port, the M2s are the pinnacle of JBL’s long history at the forefront of studio monitor technology. The M2s deliver an astonishing frequency response of 20 Hz to 40 kHz, and an extraordinary 123 dB maximum SPL that more than meets Victoria Police’s stringent performance requirements. The M2s are run bi-amped by the Crown I-Tech 4x3500HD, which delivers 4000W per channel at 4 ohms (1 kHz 20 ms burst). Each channel features a complete compliment of OMNIDRIVEHD Processing, including the acclaimed LevelMAX Limiter Suite, and support for linear phase FIR filters.

At an imposing 1.256 metres tall and weighing in at 58.5 kg, the M2s are high-performance monitors for serious applications. The often unpredictable dynamic nature of the recordings analysed by Forensic Audio means that they require monitors that can handle sudden peaks at high volume without distressing their drivers. Equally important is local support of the product, provided in abundance by Jands. The Forensic Audio Unit’s M2s were personally set-up and tuned by Jands’ audio specialist Andrew Crawford , ensuring that room response was completely flat.

Ry Wilton respects Jands attention to detail; “I was really impressed watching Jands do the tuning,” he enthuses. “Andrew could tell from modelling and measurements before he even got to the studio where the reflective surfaces, such as the doors, were located. At one point, he corrected a monitor by a mere 2 ½ degrees, after checking acoustic measurements.”

Back at the old Forensic lab at Macleod, the 30 year old JBL 4430s are still in use, and are part of Victorian Police history. Previous to their installation in Macleod, the 4430s were part of the Russel Street police headquarters. They are referenced in a book written by retired undercover police officer, relating his experience hearing an undercover recording he’d made played back through them and being astounded at the quality. At the end of their working life, they will most likely be retired with full honours to the Police Museum.


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