Difference between revisions of "Electronics project notes/Audio notes - multichannel and surround"

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Question number one is "why do this".  
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Question number one is "why do this".
  
One is that sound having no obvious direction more makes you feel like you are in the middle of things, regardless of further effects.   
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One reason is that sound having no obvious direction more makes you feel like you are in the middle of things, regardless of further effects.   
  
This is why even just replicating left and right behind you (seems to often be called multi-channel stereo) already sounds a little nicer.
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Another reason is that you can record (or mix) sound with clearer separation between instruments.
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If you've ever been sat close to a live acoustic band, or in a church with an organ that is spread throughout the building, you can appreciate the liveliness from different parts coming from different directions.
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Since you can focus on different parts more easily (turning your head), it feels like a more interactive experience. It may not apply to all music styles, and walking around is not something you'ld do every time, and this can easily conflicts with imaging, so it involves tradeoffs - which means choices, which are nice.
  
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Yet another is that you ''could'' do very detailed directional imaging. This, however, is very tricky. Hearing sounds as if they come from between speakers is possible, but requires precision in both mixing and reproduction, and various layouts are ambiguous, are prone to sounding good only in a select few sweet spots (much more so than stereo), works rather differently between headphones and speakers so can only do one in each mix, and other such issues.
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There are more footnotes than you can shake a stick at, and several weaknesses that made it into many of the systems over the years.
  
Another is that you can mix things to have more separation between instruments. If you've ever been sat close to a live acoustic band, or in a church with an organ that is spread throughout the building, you can appreciate the liveliness from different parts coming from different directions.
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There are also some more specific uses, like studio mixing. There is some argument that even if mixing down to stereo, a more-channel setup makes it easier to find certain kinds of mistakes during mixing and mastering. This doesn't apply to most of us, but is still useful in the process.
You can focus on different parts more easily, it's a more interactive experience. It may not apply to all music styles, and walking around is not something you'ld do every time, and this can easily conflicts with imaging, so it involves tradeoffs - which means choices, which are nice.
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There's also potentially better imaging - the sense of direction.
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Anyway, even just a bit of directionality turns out to be easy enough to mess up, both during recording and playback.
 
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Imaging, however, is tricky. Hearing sounds as if they come from between speakers is possible, but requires precision in both mixing and reproduction, and various layouts are ambiguous, prone to sounding good only in a few sweet spots (much more so than stereo), and other such issues - there are more footnotes than you can shake a stick at, and weaknesses that made it into many of the systems over the years.
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There is also some argument that even if mixing down to stereo, a more-channel setup makes it easier to find certain kinds of mistakes during mixing and mastering. This doesn't apply to most of us, but is still useful in the process.
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There's lots of simpler improvements - even just listening to play stereo but duplicating left and right behind you (seems to often be called multi-channel stereo) already sounds more immersed even though it's really doing very little.
  
 
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Revision as of 02:20, 13 June 2021

This is for beginners and very much by a beginner.

It's intended to get an intuitive overview for hobbyist needs. It may get you started, but to be able to do anything remotely clever, follow a proper course or read a good book.


Some basics and reference: Volts, amps, energy, power · Ground · batteries · resistors · changing voltage · transistors · fuses · diodes · varistors · capacitors · inductors · transformers · baluns · amplifier notes · frequency generation · skin effect


And some more applied stuff:

IO: Input and output pins · wired local IO · wired local-ish IO · · · · Shorter-range wireless (IR, ISM RF) · RFID and NFC · bluetooth · 802.15 (including zigbee) · 802.11 (WiFi) · cell phone

Sensors: General sensor notes, voltage and current sensing · Knobs and dials · Pressure sensing · Temperature sensing · humidity sensing · Light sensing · Movement sensing · Capacitive sensing · Touch screen notes

Actuators: General actuator notes, circuit protection · Motors and servos · Solenoids

Some stuff I've messed with: Avrusb500v2 · GPS · Hilo GPRS · JY-MCU · DMX · Thermal printer ·


Noise stuff: Stray signals and noise · sound-related noise names · electronic non-coupled noise names · electronic coupled noise · ground loop · strategies to avoid coupled noise · Sampling, reproduction, and transmission distortions


Audio notes: See avnotes

Microcontroller and computer platforms Arduino and AVR notes · ESP series notes · STM32 series notes · · · ·


Less sorted: device voltage and impedance, audio and otherwise · electricity and humans · power supply considerations · Common terms, useful basics, soldering · PLL · pulse modulation · signal reflection · resource metering · SDR · Project boxes · Unsorted stuff

See also Category:Electronics.

Why

Quadraphonic

Dolby

DTS

On layouts, and their relation to typical Dolby and DTS

Object-based audio

Sound fields over basic stereo setups

QSound

SRS

Dolby Home Theater