Bang & Olufsen invented and patented the so-called Dolby HX ( Headroom eXtension ) Pro principle for combining bias control with the Dolby system for better high frequency response in cassette recorders.

This " head room extension method, HX " was called Dolby HX Pro in full and patented.

Aside from Dolby HX, all the Dolby variants work by companding, or compressing the dynamic range of the sound during recording and expanding it during playback.

Developed in 1982, Dolby HX is not a noise reduction system, though it can indirectly decrease noise by allowing signals to be recorded at higher levels than they otherwise could.

This system was modified by Bang & Olufsen for consumer equipment and marketed by Dolby as Dolby HX Pro.

Dolby HX Pro automatically reduces the bias signal in the presence of strong high frequency signals.

Bang & Olufsen developed the HX Pro headroom extension system in conjunction with Dolby Laboratories in 1982.

However, systems such as XDR, along with the adoption of higher-grade tape ( such as chromium dioxide, but typically recorded in such a way as to play back at the normal 120 μs position ), and the frequent use of Dolby HX Pro, meant that cassettes became a viable high-fidelity option, one that was more portable and required less maintenance than records.

* Dolby HX Pro: single-ended system used on high-end tape recorders to increase headroom.

Single-ended pre-recording systems ( such as Dolby HX Pro ) work to affect the recording medium at the time of recording.

* Dolby HX and Dolby HX Pro, dynamic range headroom extension systems for analog recording on magnetic tape.

B & O was a pioneer in cassette technology, having had design involvement with Dolby HX Pro.

Just inside the perforations, on the left side of the image, is the analog optical soundtrack, with two channels encoded using Dolby Analog SR | Dolby SR noise reduction that can be dematrixed into four channels using Dolby Pro Logic.

The extra surround channel is matrix encoded onto the discrete left surround and right surround channels of the 5. 1 mix, much like the front center channel on Dolby Pro Logic encoded stereo soundtracks.

Sound design was also praised, described as " inexorably linked " to the experience and " at least very pristine " with " perfectly implemented " sound effects, running in Dolby Pro Logic II.

Prior to the advent of home theater systems, when VCRs were used, the enhanced sound option was stereo high-fidelity sound or Dolby Pro Logic for Dolby Surround-encoded tapes.

The game supports Dolby Pro Logic II setups, which allows it to be played in surround sound.

Nintendo's Wii console shares many audio components with the Nintendo GameCube from the previous generation, including Dolby Pro Logic II.

Dolby Pro Logic logo

Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround.

However, the term " Dolby Surround " is still used to describe the encoding technology or matrix-encoded soundtrack, whereas Pro Logic refers to the decoding technology and processor.

Thus Dolby Pro Logic is the consumer version of theatrical Dolby Stereo.

The B710MKII also achieved 20 – 20, 000 Hz and dynamics of over 72 dB with Dolby C on chrome and slightly less dynamic range, but greater headroom with metal tapes and Dolby C. Revox adjusted the frequency range on delivery with many years of use in mind: when new, the frequency curve went upwards a few dB at 15 – 20 kHz, aiming for flat response after 15 years of use, and headwear to match.

A typical front loading consumer autoreverse hi-fi cassette deck from late 1980s ( Sony TC-RX55 ), featuring full electronic transport, Dolby B and C noise reduction, and HXPro dynamic headroom expansion

EX adds an extension to the standard 5. 1 channel Dolby Digital codec in the form of matrixed rear channels, creating 6. 1 or 7. 1 channel output.

* Also features the lossy soundtrack Dolby Digital 5. 1 and, by extension, the lossy DTS core of the DTS-HD MA

Multiple data streams ( audio and video ) are wrapped in an ASF container with the extension DVR-MS. Video is encoded using the MPEG-2 standard and audio using MPEG-1 Layer II or Dolby Digital AC-3 ( ATSC A / 52 ).

For accurate off-the-tape monitoring during recording on 3-head decks, both processes must be employed at once, and circuitry provided to accomplish this is marketed under the rubric " Double Dolby ".

At the same time, Dolby B provided acceptable performance when played back on decks that lacked Dolby circuitry, meaning there was little reason not to use it if it was available.

Instead of the 5 screen channels and one surround channel of the Todd-AO format, Dolby Stereo 70 mm Six Track provided three screen channels, two surround channels and a low-frequency enhancement channel.

On the DVD side, most record companies ( with the notable exception of Sony Music: see below ) provided the album's music in both high-resolution, 24-bit DVD-Audio ( typically at a sample rate of 96 or 192 kHz for stereo and 48 or 96 kHz for surround sound ) and lower-resolution, 16-bit Dolby Digital sound ( typically sampled at 48 kHz ).

Because Sony had an existing high-resolution audio format, SACD, in the marketplace which directly competes with DVD-Audio ( see next section ), Sony Music, as a general rule, only provided 16-bit, 48 kHz sampled LPCM stereophonic ( and sometimes Dolby Digital Surround ) sound on the DVD side of their DualDiscs.

But it can be used with either film or digital projectors, unlike the Dolby filters that are only used on a digital system with a color correcting processor provided by Dolby.

Unlike Dolby Pro Logic II's broadband logic steering, Neo: 6 is a multi-band decoder, meaning that the decoder can enhance more than one predominant signal at a time — provided each predominant signal lies in a different frequency band than the others.

Note that access to the Ku-band DVB feeds require AC3 ( Dolby Digital ) audio capability, as there is no MPEG2 audio provided on these transponders.

Dolby SVA provided a method for putting high-quality stereo soundtracks on optical sound prints.

Apart from the problem of the bulky cassettes, the performance of standard cassettes had improved dramatically with the use of new materials such as chromium dioxide, Dolby B noise reduction, and better manufacturing quality.

After the introduction of Dolby B noise reduction for cassettes in the early 1970s, and the advent of new tape coatings that greatly improved the high-frequency response, the Compact Cassette finally became a respectable and increasingly popular medium for listening to music, both on the road and at home.

Dolby B was designed to address the high-frequency noise inherent in cassette tapes, and along with improvements in tape formulation it helped the cassette win acceptances as a high-fidelity medium.

* However, due to dbx's high compression and strong high-frequency preemphasis, dbx-encoded tapes were, unlike Dolby B, practically unplayable on non-dbx systems, sounding very harsh when played back undecoded.

The Dolby noise-reduction system works by increasing the volume of low-level high-frequency sounds during recording and correspondingly reducing them during playback.