Audyssey Dynamic EQ

What Audyssey Dynamic EQ is

Audyssey Dynamic EQ is a loudness compensation system: a bass, treble and surround-level correction that changes with the receiver's volume setting so that a film soundtrack keeps its tonal balance when played quieter than the level it was mixed at. Audyssey, founded in July 2002 out of the University of Southern California's Immersive Audio Laboratory, announced it on August 23, 2007 at CEDIA, and it first shipped in eight Denon products, including the AVR-3808CI, AVR-4308CI, AVR-5308CI and the AVP-A1HD controller. Audyssey's CEO described the aim as letting the listener set the volume at a preferred level while hearing the same bass, tonal balance and surround impression as at reference volume.

The hearing science behind it

The ear is not equally sensitive across frequency, and the unevenness changes with level. Fletcher and Munson first measured equal-loudness contours with headphones in 1933, comparing test tones to a 1,000 Hz reference tone in 10 dB steps. The definitive modern curves are in ISO 226. The ear is most sensitive between 2 and 5 kHz, which means that as playback level falls, bass and the extreme treble fall away faster than the midrange. Simple Home Cinema reports that Audyssey continued loudness-compensation research completed by THX and derived updated curves for home listening. The CEDIA release adds that Tomlinson Holman, now Audyssey's chief science officer, began researching the problem and published a seminal paper 30 years earlier.

How Dynamic EQ works in a receiver

Dynamic EQ combines information about the incoming source level with the actual output level in the room, which MultEQ calibration establishes, and makes moment-by-moment adjustments. Two things move: tonality, because bass and treble are lifted as volume falls, and the surround field, because rear channels are raised to restore envelopment that fades at lower levels. The CEDIA release states that loudness correction only works if proper frequency and time domain room equalization is done first, so Dynamic EQ is tied to MultEQ calibration, and on Denon's AVR-X3800H the Dynamic EQ menu cannot be set when MultEQ XT32 is off.

Reference is 0 dB on the receiver's volume dial. Film reference level means 85 dB continuous with 105 dB peaks per speaker and 95/115 dB for subwoofers. At the 0 dB position Dynamic EQ does nothing, and as volume comes down it lifts bass and treble progressively. Simple Home Cinema notes that the effect shrinks as the volume rises and switches off completely as you near reference, depending on the offset chosen.

Dynamic EQ vs Dynamic Volume

They are separate features that can run together. Dynamic EQ changes frequency balance only. Audyssey Dynamic Volume monitors the volume in real time and holds the listening level, which compresses dynamic range, and Denon offers Light, Medium and Heavy settings for it, defaulting to Off. On the Denon AVR-X3800H the manual says that if Dynamic Volume is set to "Yes" in Audyssey Setup, the menu setting is changed to Medium automatically. Both differ from a night mode, covered under dynamic range compression.

Reference Level Offset: the confusing setting

Denon's manual lists three offsets from film reference: 5 dB, 10 dB and 15 dB, with 0 dB as the default for movies. It recommends 5 dB for content with a very wide dynamic range such as classical music, 10 dB for jazz and for TV content, since TV is usually mixed about 10 dB below film reference, and 15 dB for pop and rock mixed at high levels with compressed dynamics. AV Gadgets points out that the manual's wording reads backward. In practice an offset moves the volume at which Dynamic EQ begins acting. With the 5 dB offset, compensation engages when the dial is lower than -5 dB; the 10 dB offset engages it lower than -10 dB, and so on. Simple Home Cinema runs an offset of 5 dB all the time, and AV Gadgets recommends leaving the setting at the 0 dB default.

The related Surround Level Compensation control sets how much the rear channels are raised. On the Denon manual the default Heavy setting raises surround and rear channels by up to 8.5 dB based on the master volume, Medium by up to 5.6 dB and Light by up to 2.8 dB.

Which receivers and modes support it

It is part of the Audyssey package in Denon AVRs, and Home Theater Academy lists Marantz and Onkyo among the brands that use Audyssey. In the Denon AVR-X3800H manual, Dynamic EQ, Reference Level Offset and Dynamic Volume settings are stored per input source, and they cannot be configured in Direct or Pure Direct mode, in DTS Virtual:X modes, or when a DTS:X signal has a sampling frequency above 48 kHz. Dynamic EQ also disables the receiver's Tone control while it is on, because both would be adjusting the same tonal balance.

Common confusions

It is not a bass boost, because it leaves a reference-level mix untouched. It is not room correction, which is MultEQ XT32. Reference level here means the 0 dB dial position after calibration; for the SPL math, see reference level. And a house curve that adds a few dB of bass is a fixed correction, whereas Dynamic EQ changes with volume. Simple Home Cinema argues that complaints that Dynamic EQ is too aggressive usually trace back to microphone placement, subwoofer placement or an untreated room, which is an opinion and not a measurement.