Audyssey, Dolby and DTS


What the heck is this Audyssey thing and all these new audio modes? In short, you use a little microphone, the system walks you through 6-8 listening locations and it trys to calculate the right equalization (that is which speakers should be louder or softer) and does it dynamically as people hear different frequencies better at different noise levels. That is what Dynamic EQ is.

They also have something called Dynamic Volume which essentially listens to the source input and changes the volume automatically. That is softer parts of a movie get louder and vice versa. I’m not sure how it really does this and if it really works.

Audyssey: Frequently Asked Questions

The first microphone position must always be in the center of the listening area. Then we recommend moving the mic about two feet to the left of that first position for measurement two and two to the right of the original spot for measurement three.

If you are running MultEQ or MultEQ XT you should use all six or eight measurements available. The next three should be taken about two feet in front of the first three. The final two measurements (if available) should be about one foot to the left and right of the first central measurement and about one foot forward to form a triangle.

You should avoid taking measurements that are too far off to the side and outside the front Left and Right loudspeakers even if there are seats there. These measurements will suffer from a drop in high frequencies and can cause the room correction filters to compensate for that unnecessarily.

Also avoid taking measurements too close to the back wall even if the only listening seats are up against the wall. Move the mic at least one foot from the back wall to avoid the bass build-up that happens there.

Audyssey: Frequently Asked Questions

The Audyssey Flat setting uses the MultEQ filters in the same way as the Audyssey curve, but it does not apply a high frequency roll-off. This setting is appropriate for very small or highly treated rooms in which the listener is seated quite close to the loudspeakers. It is also recommended for all rooms when the receiver is in THX processing mode. This allows THX re-equalization to operate exactly as it was intended.

This seems as clear as mud to me, but here’s an explanation in Denon 3806 Audyssey “Flat”? [Archive] – Audioholics Home Theater Forums

If you have the EQ set to Audyssey, the EQ will add a bit of high frequency roll-off in addition to the room compensation. The HF rolloff is for taking the brightness out of DVD’s that have not been equalized for the difference between movie theaters and home theaters. The rolloff is supposed to be similar to the effects you would get from Denon’s “Cinema EQ” setting.

With the EQ set to Flat, there is no HF rolloff, just room compensation. The only difference between the Audyssey setting and the Flat setting is in the high frequencies; mid-range, bass, etc. should be the same for either setting. The recommended setting for listening to music is Flat.

So what does Dolby TrueHD or the also lossless DTS-HD Master Audio do with equalization. How are you supposed to know if a BluRay movie is too bright or there is a correction? What are all these a names anyway:

Dolby – Technology Overview: Definitions of Dolby’s Technologies

Dolby® TrueHD is Dolby’s latest lossless technology, the ultimate audio experience for high-definition disc-based media. Dolby TrueHD on Blu-ray Disc™ allows viewers to hear exactly what was captured during the recording and mastering process, bringing a palpable and involving audio presence to the home theater experience. 18Mbps, loss-less, 5.1 24-bit/192KHz audio

Dolby Digital Plus is the next-generation audio format that delivers “better-than-DVD” sound in high-definition packaged media because it requires less compression and provides more channels (up to 7.1). Dolby Digital Plus also provides new coding efficiencies for future broadcasting and streaming of multichannel audio. 6Mbps, compressed lossy format, standard for broadcast HDTV

Dolby Digital EX introduces a center rear channel to 5.1-channel playback, expanding the surround sound experience to 6.1 or 7.1 channels. It intelligently identifies audio information in the left and right surround channels. One or two speakers placed behind the listener provide increased realism for front-to-back sounds and those originating from directly behind the listener.

Dolby Digital is a powerful audio format that provides up to 5.1 separate channels of crystal-clear digital surround sound, bringing entertainment to life. A worldwide standard in film, broadcast, and DVDs, Dolby Digital delivers unrivaled audio in home theater systems for an exciting, enveloping surround sound experience. The thing on most DVDs now.

Dolby Surround technology encodes four channels of audio (Left/Center/Right/Mono Surround) onto just two audio tracks for media such as TV broadcasts and feature films on VHS. On systems containing Dolby Pro Logic® technology, the audio is reconstructed to its original four-channel surround sound.

DTS | Technology | At A Glance

DTS-HD Master Audio provides lossless audio that matches, bit-to-bit, the original movie’s studio master soundtrack and is fully backward-compatible with all DTS decoders. 7.1.

DTS Digital Surround is the standard for providing 5.1 channels of discrete digital audio in consumer electronics products and software content. There is a core standard called DTS which supports 5.1 compressed at 1.5Mbps.  Then extensions which receivers can ignore caled  DTS-ES, DTS-96/24 and DTS Neo:6. These are really complicated. DTS-ES Discrete has 6.1 discrete channels whereas DTS-ES Matrix encodes the 6th channel inside the others. DTS-96/24 increases encoding to 96

DTS-ES is the only digital audio format capable of delivering 6.1 channels of discrete audio in the consumer electronics market. DTS-ES is also fully backwards-compatible with DTS decoders that are not Extended Surround equipped. DTS 96/24 DTS 96/24 DTS 5.1 and DTS 96/24 decoding inside The disc is encoded with DTS 96/24 and is playable in 96/24 with any DTS 96/24-equipped hardware. Fully compatible with DTS-capable 5.1 hardware, and backward-compatible (at 48/24) to all DTS-equipped hardware.

DTS Neo:6 DTS Neo:6 DTS Neo:6 is available in all DTS-ES-equipped receivers.

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