TC Electronic Introduces More Industry-first Features for DB4 and DB8 Processors

The 3.40 upgrade includes a new Advanced Loudness Correction processor, ALC6, and LKFS reading for the Radar Loudness Meter, LM6. The upgrade is free of charge to all users of DB4 and DB8 - original version as well as MKII.

ALC6 offers BS.1770 compliant Loudness Correction and True-peak limiting for mono, stereo and 5.1 programs. This low latency, 48-bit resolution processor introduces several industry-first features.

Broadcasters around the world are going through a transition towards loudness based production and program normalization. In order to comply with legislation such as the CALM Act, as a quick fix, it's tempting to insert 'sausage processing' at the point of transmission. However, sausage processing is completely against the spirit and the purpose of new American, Brazilian, Chinese, European and Japanese audio standards. With ALC6, processing happens at a higher resolution than any other audio device or codec in the broadcast signal path, and therefore DB4 or DB8 will never be the quality bottleneck.

Further, ALC6's adaptive Stridency Reduction parameter brings overly loud content under tight control while leaving normal content untouched. Another industry-first parameter allows the operator to indicate whether a program is already normalized, not normalized or sometimes normalized.

If the content is in 5.1 surround, ALC6 may automatically dissolve into bypass, or you may set a different Target Level depending on the format. ALC6 is transparent in several senses of the word.

Downmix Compliance
Measuring the loudness of a 5.1 program can give significantly different results from measuring a stereo or a mono downmix of the same program. Also, these differences are systematic because measuring loudness according to BS.1770 is insensitive to inter-channel phase differences, while a downmix is not. Tight tolerance on program loudness therefore presents a dilemma when it comes to mono or stereo listeners, generally the vast majority of a station's audience. ALC6 introduces a new way of dealing with this issue: A 5.1 program may be adjusted based on what it measures in 5.1, or on what it measures using a specific set of downmix coefficients.

ALC6 also helps getting a higher audio quality and more headroom out of AC3 data reduction. The downmix part of the decoder is prone to overload, especially when AC3 DRC is set to 'Off'. On the other hand, enabling DRC inserts a crude processor, which nobody can get rid of again. The new 'AC3 Codec' setting with ALC6's True-peak Limiter prevents downmix clipping while preserving headroom, thereby making it safe to switch off DRC and make AC3 more transparent.

Preset Compatibility
For a happy ending, ALC6 even reads presets made with its predecessor, the industry-standard ALC5.1. The operator therefore hits the ground running after the upgrade, and may try all of its features one by one.

DB4 and DB8's integrated Radar Loudness Meter, LM6, includes two new functions: The meter may now show loudness units in 'LKFS' rather than 'LUFS', and a Short-term loudness warning threshold may be set. Real-time loudness warnings are visible in the remote application on a Mac, a PC or on the TC Icon hardware unit. Warnings are also relayed via the processor's extensive SNMP alert and logging system.