surround

Description: The circuits and wiring diagrams provided have been tested on multiple hi-fi stereo systems without causing any damage. However, responsibility cannot be assumed for any unconventional designs that may be harmed by improper speaker connections. Use these circuits at your own risk. After reviewing numerous articles on surround sound, it has been observed that many authors have not conducted thorough research. Some attribute the origin of surround sound to the 1976 film Star Wars, while others reference the unsuccessful marketing of quadraphonic stereo in the early 1970s. The earliest mention of what is now referred to as surround sound appears to be a documentary about the making of Disney's 1940 film, Fantasia. The idea of incorporating a third channel into a stereo signal is straightforward and likely conceived soon after the development of stereo sound. Star Wars was released in a six-channel stereo format that had existed for at least 15 years by 1976. It is posited that surround sound became widely adopted for movie prints intended for theaters without expensive multichannel sound systems, with home theater surround sound emerging as a result. There is no need to re-record sound for home video, as once a movie is encoded with surround sound, it remains for the home video release. In standard stereo, separate signals are directed to individual speakers, one on the right and one on the left, creating an auditory experience that may seem to originate from either speaker or from a space between them. When recording a stereo signal, microphones are positioned to ensure that sounds reach each speaker at the appropriate levels, allowing instruments in an orchestra to appear to come from their respective locations. Stereo sound functions effectively only when speakers are in phase, meaning they are wired to operate in unison. For speakers to be in phase, their cones must move together; both must move toward the listener simultaneously and then away at the same time. If one speaker is wired incorrectly, the speakers will operate out of phase, resulting in a collapse of the stereo effect where sounds may seem to emanate from all directions between the speakers. To confirm that speakers are in phase, tune to an AM radio station or use another non-stereo signal, adjusting the volume equally on both speakers; the sound should appear to originate from a single point between the speakers. If not, the speakers are out of phase, and reversing the wires on one speaker will correct this. Encoding surround sound is straightforward; the third channel is mixed into the left channel as if it were another microphone channel, but its phase is reversed before being mixed with the right channel. This mimics the effect of having the right speaker's wires reversed but only for sounds encoded for the third channel. Consequently, sounds intended for the left and right speakers will sound normal, while those for the third channel may be difficult to locate.

The description of the circuit and wiring diagrams illustrates a foundational understanding of stereo and surround sound systems, emphasizing the importance of proper speaker wiring and phase alignment for optimal audio performance. The circuits are designed to facilitate the implementation of surround sound by ensuring that the audio signals are accurately processed and delivered to the appropriate channels.

In a typical stereo setup, two channels (left and right) deliver audio through respective speakers, creating a spatial sound experience. The addition of a third channel for surround sound enhances this experience by providing audio cues that create a more immersive environment. The design of the circuit must account for the phase relationships between the channels, ensuring that the audio signals are mixed correctly to prevent any loss of sound quality or spatial accuracy.

For effective implementation, the circuit should include a mixer capable of handling multiple audio inputs, with provisions for phase reversal on the third channel. The mixer should be designed to maintain the integrity of the left and right channels while allowing for the unique characteristics of the third channel. Additionally, the wiring must be robust enough to handle the power levels associated with hi-fi systems, with attention paid to the quality of connectors and cables used to minimize signal loss.

In conclusion, the successful application of these circuits and wiring diagrams relies on a comprehensive understanding of audio signal processing, phase relationships, and the specific requirements of surround sound systems. Proper implementation will result in an enhanced audio experience, capable of delivering high-fidelity sound in both home theater and professional audio environments.The circuits and wiring diagrams below have been tested on several hi-fi stereo systems with no damage to the systems. However, I cannot be responsible for some hair-brained engineer who may have used a radical design that might be damaged by an unorthodox speaker hookup.

Use these circuits at your own risk. After reading many articles about surro und sound I have come to the conclusion that most of the writers haven`t done their homework. Some writers trace the origin of surround sound to the 1976 movie Star Wars. Others trace it to the abortive attempts at marketing quadraphonic (four-channel) stereo in the early 1970`s. Where did surround sound originate; what was the first surround sound movie So far, the earliest reference I have seen to what is now called surround sound was a documentary on the making of the 1940 Disney movie, Fantasia.

The concept of encoding a third channel into a stereo signal is so simple that I`m sure it was thought of as soon as stereo sound was developed. What about Star Wars Star Wars was released in a six-channel stereo format which was already at least 15 years old in 1976.

I suspect the truth is that, starting with Star Wars, surround sound became almost universally used for movie prints destined for theaters lacking the more expensive multichannel sound systems. Home theater surround sound is simply a by-product of these prints. There is no need to re-record the sound for home video. Once a movie is encoded with surround sound, it remains with the movie for the home video release. With standard stereo, the separate signals are sent to separate speakers, one to the right of the listener and one to the left.

The sounds produced by the speakers may seem to come from one speaker or the other, or may seem to come from empty space anywhere between the speakers. When a stereo signal is recorded, microphones are placed so that the sounds in each speaker is at the correct level to make sounds seem to come from the directions they originated form.

Because of this all of the instruments of a symphony orchestra will seem to come from their proper places between the speakers; violins, trumpets and timpani toward the left; violas, woodwinds and horns toward the center; cellos, basses and trombones toward the right. Stereo sound, as described above, works only if the speakers are in phase, meaning that the speakers are wired to work in unison.

To be in phase, the speaker cones must move together; they must move toward the listener at the same time and must move away from the listener at the same time. If you accidentally wire one (but only one) speaker backwards, the speakers will work out-of-phase; one speaker cone will be moving toward the listener while the other speaker cone is moving away from the listener and vice versa.

This causes a total collapse of the stereo effect. All sounds will seem to come from everywhere between the speakers at once or may seem to come from both speakers at once. To be sure your speakers are in phase; tune to an AM radio station (or use another non-stereo signal); adjust the volume to be equal in both speakers.

The sounds should seem to be coming from a single point in space between the speakers and nowhere else. If this is not the case, the speakers are out-of-phase. To fix the phasing, reverse the wires on one (and only one) speaker. Encoding surround sound is very simple. The third channel is simply mixed into the left channel as if it were any other microphone channel. However, before being mixed with the right channel, the phase of the third channel is reversed. This has the same effect as if the wires on the right speaker were reversed, but only for sounds encoded for the third channel.

Therefore, sounds intended for the left and right speakers will sound normal. Sounds encoded for the third channel will be hard to locate and may even be lost in the shuffle unless deliberately listened for. In order for a