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I have to admit that I was experimenting last night with Pacific’s Low Level Extension and it was not bad at all. It would not be my last words as I would need the whole system up and running to see what is going on – the region where the Low Level Extension it operates is VERY demanding. However my initial feelings were very positive. The Low Level Extension is not EQ but a dynamic-range-sensitive EQ – quite brilliant idea – through I do not know yet how it will sound at full bloom. The classical CD of References Recordings are a good illustration how it works….Anyhow, it is very exiting feature to play with… though I do admit that it is a forum of a compression….

From Pacific Microsonics Operating Manual: (disregard the text mentioning HDCD – I do not use HDCD encoding neither A/D nor in D/A)

Low Level Extension

Low Level Extension is an average signal level based low level compression / expansion system used on HDCD 16-bit amplitude encoded recordings which very gradually raises gain a preset amount when the average signal level drops below a preset threshold. During HDCD 16-bit decoded playback the compression curve is expanded back to linear gain by the HDCD decoder using a precisely mapped inverse of the compression curve controlled by a hidden code, producing a dynamic range and resolution floor beyond 16-bit. During undecoded playback low level information normally lost by standard 16-bit players is preserved, providing more accurate timbral and spatial reproduction.

There are two modes of Low Level Extension, “Normal” and “Special”. Normal mode begins to affect the input signal 45 dB below peak level, gradually raising the gain 4 dB as the level drops over an 18 dB range. Special mode begins to affect the input signal 39 dB below peak level, and gradually raises the gain 7.5 dB over a 26 dB range. Normal mode is optimized to provide the best combination of decoded dynamic range and resolution and nundecoded compatibility. Special mode is designed to provide the best possible decoded dynamic range and resolution at some potential expense of undecoded compatibility. Typically, Special mode is used only for HDCD 16-bit master tracking with the assumption that the recording will be decoded to a 24-bit or 20-bit word length for digital post production before being re-encoded to HDCD 16-bit using Normal mode to produce a release master.

Wide Dynamic Range Jazz or Classical

This type of material typically has infrequent, short duration peaks such as snare drum rim shots, cymbal crashes, bass drum hits, etc. These types of short duration peaks can be limited by as much as 5 dB or 6 dB using Peak Extension with little audible effect during undecoded playback, allowing the average recorded level to be raised which improves overall resolution and fidelity.

Low Level Extension, set to Normal mode, should almost always be used with wide dynamic range material as it greatly aids in preserving the low level ambient and timbral information that gives “life” and naturalness to recordings.

With certain types of source material, such as a very low level passage in a noisy analog tape, Low Level Extension may occasionally cause an audible shift or “breathing” of the noise floor during undecoded playback. Low Level Extension can be turned off “on the fly” prior to such passages when the signal level is above - 30 dBfs, and turned back on afterwards, again when the signal level is above - 30 dBfs, to preserve the best possible fidelity for the remainder of the recording. However, with source material that is very noisy, Low Level Extension should be left off, as the noise of the source will set the resolution floor.

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