
Introduction
Audio interconnects and sound quality are often overlooked, with more emphasis being placed on video Connections and video quality. Focusing on video quality is a mistake with audio providing an important dimension to the Home Theater Network experience. Surround sound can make movies feel life-like, with sounds buzzing from left to right. The type of audio interconnecst and audio signals you use will affect the sound experience of your Home Theater Network. When possible, always use digital audio interconnects (digital coaxial, optical, HDMI, i.Link) over analog.
Audio Signals
There are many types of audio signals that get transmitted through cables. Audio signals vary from digital to analog. Dolby, DTS, and S/PDIF are popular ways of encoding analog sound into digital. Digital audio signals are typically transmitted through RCA, optical, HDMI, and i.Link interconnects, while analog audio signals are typically transmitted through RCA and speaker interconnects. Below is a list of common audio signals.
- DTS – a digital 5.1 surround sound format with separate audio data for each channel. DTS (Digital Theater Systems) can also play mono or stereo audio. Lossy data compression is used to convert analog audio into digital audio at a maximum of 1.5 Mb/s.
- DTS ES – the same as DTS, but with an extra rear center channel for 6.1 surround sound. The rear center channel can have two speakers playing the same sound to make a 7.1 surround sound system.
- DTS HD – a digital 7.1 surround sound format with separate audio data for each channel. DTS-HD will have lossless data compression, which technically means the audio should be exactly the same as the master. The maximum sampling frequency for each discrete channel will be 192 kHz.
- DTS Neo:6 – used to convert regular 2-channel audio into 6.1 surround sound. The audio conversion is still limited to 1.5 Mb/s.
- Dolby Digital 5.1 – a digital 5.1 surround sound format with separate audio data for each channel. Can also play mono or stereo audio. Dolby Digital uses lossy data compression to convert analog audio into digital audio at a maximum of 448 kb/s (1Mb = 1000kb).
- Dolby Digital EX – the same as Dolby Digital, but with an extra rear center channel for 6.1 surround sound. The rear center channel can have two speakers playing the same sound to make a 7.1 surround sound system.
- Dolby TrueHD – a digital 7.1 surround sound format with separate audio data for each channel. Like DTS-HD, Dolby TrueHD will have lossless data compression. However, the maximum sampling frequency for each discrete channel of Dolby TrueHD will be 96 kHz instead of the 196 kHz used by DTS-HD. The maximum audio bit depth of Dolby TrueHD is 24 bits.
- Dolby Pro Logic I – used to convert regular 2-channel audio into 4 separate channels. The audio conversion is still limited to 448 kb/s.
- Dolby Pro Logic II – an update to Dolby Pro Logic I with an additional channel to produce 5.1 surround sound.
- Dolby Pro Logic IIx – an update to Dolby Pro Logic II with an additional channel to produce 6.1 surround sound.
- Dolby Surround – encodes four channels (front left, front right, center, and rear) into a two channel signal.
- S/PDIF – transmits digital audio signals in various formats. The most common sampling frequencies are 48kHz and 44.1KHz with resolutions of 20 or 24 bits. The S/PDIF digital signal is commonly used by computers.
- LPCM – stands for Linear Pulse Code Modulation. LPCM takes analog signals and converts them into uncompressed digital signals. The sampling frequency can be 48 kHz or 96 kHz with 16, 20, or 24 bits per sample. Up to 8 channels can be encoded.
- Analog – audio is sent in an analog format. This is commonly used in the left and right RCA interconnects and speaker interconnects.
- LFE – stands for Low Frequency Effect. LFE is an analog signal designed to go to a subwoofer. The low frequency bass that this signal carries is limited in range from 20 Hz to a maximum of 150 Hz.
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