In a digital recording system, sound is stored and manipulated as a stream of discrete numbers, each number representing the air pressure at a particular time. The numbers are generated by a microphone connected to a circuit called an ANALOG TO DIGITAL CONVERTER, or ADC. Each number is called a SAMPLE, and the number of samples taken per second is the SAMPLE RATE. Ultimately, the numbers will be converted back into sound by a DIGITAL TO ANALOG CONVERTER or DAC, connected to a loudspeaker.

The number of bits in the number also determines the dynamic range. Moving a binary number one space to the left multiplies the value by two (just as moving a decimal number one space to the left multiplies the value by ten), so each bit doubles the voltage that may be represented. Doubling the voltage increases the power available by 6 dB, so we can see the dynamic range available is about the number of bits times 6 dB.

Sample Rate
The rate at which the numbers are generated is even more important than the number of bits used. Figure 3. illustrates this. If the sampling rate is lower than the frequency we are trying to capture, entire cycles will be missed, and the decoded result would be too low in frequency and might not resemble the proper waveform at all. This kind of mistake is called aliasing. If the sampling rate were exactly the frequency of the input, the result would be a straight line, because the same spot on the waveform would be measured each time. This can happen even if the sampling rate is twice the frequency of the input if the input is a sine or similar waveform. The sampling rate must be greater than twice the frequency measured for accurate results. (The mathematical statement of this is the Nyquist Theorem.) This implies that if we are dealing with sound, we should sample at least 40,000 times per second.

Recording Digital Data
Once the waveform is faithfully transformed into bits, it is not easy to record. The major problem is finding a scheme that will record the bits fast enough. If we sample at 44,100 hz, with a sixteen bit word size, in stereo, we have to accommodate 1,411,200 bits per second. This seems like a lot, but it is within the capabilities of techniques developed for video recording. (In fact, the first digital audio systems were built around VCRs. 44.1 khz was chosen as a sample rate because it worked well with them.)

To record on tape, a very high speed is required to keep the wavelength of a bit at manageable dimensions. This is accomplished by moving the head as well as the tape, resulting in a series of short tracks across the tape at a diagonal.

On a Compact Disc, the bits are microscopic pits burned into the plastic by a laser.The stream of pits spirals just like the groove on a record, but is played from the inside out.To read the data, light from a gentler laser is reflected off the surface of the plastic (from the back: the plastic is clear.) into a light detector. The pits disrupt this reflection and yield up the data.

In either case, the process is helped by avoiding numbers that are hard to detect, like 00001000. That example is difficult because it will give just a single very short electrical spike. If some numbers are unusable, a larger maximum (more bits) must be available to allow recording the entire set. On tape, twenty bits are used to record each sixteen bit sample, on CDs, twenty-eight bits are used.

Error Correction
Even with these techniques, the bits are going to be physically very small, and it must be assumed that some will be lost in the process. A single bit can be very important (suppose it represents the sign of a large number!), so there has to be a way of recovering lost data. Error correction is really two problems; how to detect an error, and what to do about it.

The most common error detection method is parity computation. An extra bit is added to each number which indicates whether the number is even or odd. When the data is read off the tape, if the parity bit is inappropriate, something has gone wrong. This works well enough for telephone conversations and the like, but does not detect serious errors very well.

In digital recording, large chunks of data are often wiped out by a tape dropout or a scratch on the disk. Catching these problems with parity would be a matter of luck. To help deal with large scale data loss, some mathematical computation is run on the numbers, and the result is merged with the data from time to time. This is known as a Cyclical Redundancy Check Code or CRCC. If a mistake turns up in this number, an error has occurred since the last correct CRCC was received.

With this scheme, you could lose eight words, but they would represent several isolated parts of the data stream, rather than a large continuous chunk of waveform. When a CRC indicates a problem, the signal can be fixed. For minor errors, the CRCC can be used to replace the missing numbers exactly. If the problem is more extensive, the system can use the previous and following words to reconstruct a passable imitation of the missing one. One of the factors that makes up the price difference in various digital systems is the sophistication available to reconstruct missing data.

The Benefits of Being Digital
You may be wondering about the point of all of this, if it turns out that a digital system is more complex than the equivalent analog circuit. Digital circuits are complex, but very few of the components must be precise; most of the circuitry merely responds to the presence or absence of current. Improving performance isusually only a matter of increasing the word size or the sample rate, which is achieved by duplicating elements of the circuit. It is possible to build analog circuits that match digital performance levels, but they are very expensive and require constant maintenance. The bottom line is that good digital systems are cheaper than good analog systems.

Digital devices usually require less maintenance than analog equipment. The electrical characteristics of most circuit elements change with time and temperature, and minor changes slowly degrade the performance of analog circuits. Digital components either work or don't, and it is much easier to find a chip that has failed entirely than one that is merely 10% off spec. Many analog systems are mechanical in nature, and simple wear can soon cause problems. Digital systems have few moving parts, and such parts are usually designed so that a little vibration or speed variation is not important.

In addition, digitally encoded information is more durable than analog information, again because circuits are responding only to the presence or absence of something rather than to the precise characteristics of anything. As you have seen, it is possible to design digital systems so that they can actually reconstruct missing or incorrect data. You can hear every little imperfection on an LP, but minor damage is not audible with a CD.

The aspect of digital sound that is most exciting to the electronic musician is that any numbers can be converted into sound, whether they originated at a microphone or not. This opens up the possibility of creating sounds that have never existed before, and of controlling those sounds with a precision that is simply not possible with any other technique.

Mackie DXB	Mackie DXB What’s most obvious about the dXb is its dual 15" touchscreens. These screens are really the heart of the mixer and its main interface. Naturally, they display all the things you’d expect from a top-of-the-line digital desk, like levels, routing, dynamics processing, surround panning and effects. But what’s not evident until you use this console is how well they do so. It’s the "little" things, like transparent windows, incredibly elegant yet intuitive graphics, and immense flexibility that really sets this interface apart. Features: 96k digital mixing console with 72-channel I/O matrix Selectable 192k operation with 36-channel I/O matrix Firewire I/O cards for streaming audio to/from desktop or laptop computers Dual 15" touch-screen graphic user interfaces plus mouse control Twenty-five 100mm Penny + Giles motorized optical touch-sensitive faders Full dynamics and parametric EQ on every channel, input and output Onboard support for select VST plug-ins 8-channel surround mixing and monitoring capabilities Onboard Universal Audio LA-2A and 1176LN compression, Pultec Program EQ, Cambridge EQ, Dreamverb and more via integrated UAD-1 Powered Plug-Ins card Tape-style transport with memory location recall and Jog/Shuttle wheel Comprehensive automation system with event editing and dynamic/scene automation Wide variety of Mackie and third-party I/O cards available for support of all major analog or digital connections RS-422 (Sony® 9-pin), LTC, MTC, MMC, and Word Clock sync Mackie Control Universal mode for control of Pro Tools, Logic and many other DAW applications
Soundcraft 328DX	Soundcraft 328DX Not just an amazing console in it's own right, the 328XD is designed to integrate completely with desktop packages. Using the 328XD as a hardware controller and combining its mixing engine with that of a desktop sequencer produces one huge, awesome production centre. Indeed, with its 56-bit internal processing, it makes sense to run desktop audio channels through the 328XD at mixdown. MIDI-OX - Download it at www.midiox.com Interfaces to ADAT, TDIF, S/PDIF and AES/EBU as standard (no cards) E-Strip technology - See parameters the way you want to Legendary Soundcraft EQ and Dynamics processing Up to 42 inputs at Mixdown, plus 8 groups, and 16 direct outputs. 16 Mic/Line and 5 stereo inputs 16 digital inputs ( or tape returns ) in ADAT™ Optical and TDIF™ formats Integrated meterbank for all inputs and outputs 2 high resolution superb quality Lexicon effects units 100mm motorized faders, comprehensive dynamic automation 24-bit ADCs and DACs (128x oversampling) & 56-bit internal processing MIDI Controller mode to remote control your sequencers & synths
Tascam DM-24	Tascam DM-24 Digital Mixing Console 24-bit, 96kHz compatible Flexible 32-channel/8-bus console with 6 aux sends Included digital I/O: 24 channels of TDIF, 8 channels of ADAT, (2) two channel AES/EBU and (2) two channel S/PDIF 16 new mic pres, 16 balanced mic/line inputs on XLR & TRS jacks and 16 inserts (2) option slots for additional interface modules (Firewire, AES/EBU, TDIF, ADAT & Analog) or a Cascade module for linking two DM-24s together. Powerful built-in automation (no computer required) High-quality, configurable Compressor and four band, parametric EQ on each channel. Channels 1-16 also feature a high quality Gate/Expander (2) built-in effects processors with reverb, spatial effects and mic/speaker modeling effects by TC Works(tm), Antares(tm) and TASCAM Comprehensive user interface, featuring large LCD screen and LED ring encoderSeventeen 100mm touch-sensitive moving faders
Mackie D8B	Mackie D8B From Grammy-winning producers and engineers like Walter Afanasieff , Don Was, and Ed Cherney, to artists like Crystal Method and Naughty By Nature, the D8B is the standard for powerful, easy-to-use digital mixing. When you sit down at a Digital 8•Bus, you'll feel as well as hear a difference. It is as intuitive and easy to use as an analog console because the D8B is the only mid-sized digital console designed by large-console automation specialists. Now, with 5.1 software and a wealth of 3rd-party plug-ins, the D8B boasts an incredibly sexy new interface, Pro Tools control capabilities, Surround monitoring and so much more.
Yamaha 24-Bit/96kHz	Yamaha 24-Bit/96kHz 01V! Digital audio technology has come a long way since the early days of 16 bits at 44.1 kHz - a format that many considered to be the reason for "harsh", "cold" sound. The entire industry is now settling on 24-bit/96-kHz digital operation for significantly superior sonic quality. The 01V96 does give you a choice - you can work at 44.1 kHz, 48 kHz, 88.2 kHz, or 96 kHz, depending on the needs of each individual project. But when you want the truly transparent, incredibly dynamic sound of 24-bits at 96 kHz, the 01V96 is ready to deliver. It even includes a comprehensive range of superb 96-kHz compatible stereo effects with 32-bit internal processing. 24 Analog & Digital Channel Inputs ... Expandable to 40 Right out of the box the 01V96 gives you 16 analog channel inputs - 12 with high-performance microphone head amplifiers - and eight digital channel inputs via a built-in ADAT optical interface. The first 12 analog channels will accept microphone signals or balanced/unbalanced line-level signals, while the remaining four channels can be used either as individual balanced/unbalanced line inputs or two stereo pairs. Without going any further you're ready to handle a comprehensive mix of analog and digital inputs. When you need more, Yamaha offers a range of Mini-YGDAI expansion cards that can simply be plugged into the 01V96 expansion slot to provide additional I/O in a variety of formats: ADAT, AES/EBU, TDIF or analog.
Yamaha 02R96	The Yamaha 02R96 inherits key features from Yamaha's DM2000 Digital Production Console - 96 kHz audio, surround monitoring, studio manger software, DAW control and host of additional features - but is amazingly affordable at 1/2 the cost! This incredible value means you can get the console you need today and add to it as your need grows! The O2R96 makes the most advanced technology for commercial sound and music production available to a broad range of engineers and facilities - at an affordable price! High Resolution! Unlike conventional equipment that achieves operation in 96 kHz mode with reduced number of channels, the 02R96 imposes no such limitations, whether at 44.1 kHz, 48 kHz, 88.2 kHz or 96 kHz. Full 96 kHz resolution with 32-bit internal processing and 58-bit accumulators is the standard. You get 56 channels of transparent, superdynamic 24-bit/96 kHz audio, plus all the additional effects and processing you'll ever need for most applications. Yamaha has included a comprehensive range of 96 kHz compatible stereo effects with 32-bit internal processing in the 02R96 - plus several designed specifically for surround. And you can use as many as four individual effect processors simultaneously. All onboard A/D and D/A conversion makes use of the finest 24-bit/96 kHz converters. The onboard converters ensure that you get an excellent digital representation of the warm, transparent output from these remarkable mic preamps. I/O capability is also in line with the rest of the console's performance: four I/O slots accept a new range of 24-bit/96-kHz-capable Mini-YGDAI digital and analog I/O cards as well as existing types.
Baby HUI	Baby HUI™ is the direct descendant of it's predecessor HUI™ (Human User Interface). HUI was originally released by Mackie in 1997, and quickly became one of the audio industry's first totally integrated control surfaces for digital audio workstations. With a similar feature set of single-button automation, editing, and navigational commands, complimented with eight full-featured channel strips that feature a touch-sensitive motorized fader, Baby HUI offers professional-grade features and capabilities in a compact, affordable package
Mackie Control	Mackie Control Universal is much more than a way to balance levels. It gives you realtime control over your music in ways your keyboard and mouse never will. With 100mm Penny+ Giles optical touch faders, a full sized backlit LCD, V-Pots for fast tweaking of effects and plug-ins, a full implementation of Logic Control, and shortcut navigation and editing for all major software including Pro Tools, this is the first and last desktop controller you will ever need. At just one-third of the cost of other professional systems, with expandability via optional Control Extenders, Mackie Control Universal gives you the perfect hands-on surface to make music faster--no matter what software you use. Features: New full implementation of Emagic Logic Control Digidesign Pro Tools control via HUI 100mm Penny + Giles Motorized Touchfaders Multi-function V-Pots for fast control of panning and effects Comprehensive Automation controls Full Meter Display with track names and parameters 7-segment Timecode display Software-specific Lexan overlays
Tascam FW-1884 and the new FW-1082	Tascam FW-1884 FireWire Audio/MIDI Interface & Control Surface Comprehensive mixing, automation, editing and navigation tools for DAWs Eight 100mm motorized touch-sensitive channel faders, one motorized touch-sensitive master fader Dedicated controls for pan, solo, mute and select functions on each channel; tactile control for four bands of parametric EQ Shortcut keys for various popular audio software applications Eight balanced XLR analog mic/line inputs with high quality mic preamps Phantom power and inserts on every channel 24-bit/96kHz A/D and D/A converters; full 96kHz operation on all analog I/O channels with compatible DAW software Eight channels of ADAT lightpipe, stereo S/PDIF inputs and outputs. Eight analog outputs, allowing connection of L/R and 5.1 surround matrices Dedicated headphone output Four MIDI inputs, four MIDI outputs Tascam FW-1082 Now Includes Steinberg Cubase LE and TASCAM GigaStudio 3 LE! The TASCAM FW-1082 Audio/MIDI Interface and Control Surface from TASCAM not only provides tons of audio and MIDI I/O to small studios, but offers a control surface with moving-faders for a previously unheard-of price. The FW-1082 features 10 inputs, including four balanced XLR mic inputs with phantom power. Two MIDI inputs and outputs are also included, plus S/PDIF digital I/O. Eight channel strips each feature a 60mm touch-sensitive moving fader and select/solo/mute buttons, and a moving master fader is also provided. The FW-1082 includes the latest TASCAM software bundle: Cubasis LE 96kHz/48-track recording software, GigaStudio 3 LE streaming sampler and Nomad Factory plug-in demos. The FW-1082 is a great choice for small studios, whether someone is just starting out or if they're upgrading their equipment. Its four microphone inputs, two with analog insert jacks, have phantom power for professional condenser microphones. Four additional line inputs and a S/PDIF stereo input add up to 10 inputs simultaneously, each at 96kHz/24-bit audio resolution. Two MIDI inputs and outputs are provided for 32 channels of MIDI synth playback or control. The control surface has nine 60mm touch-sensitive moving faders for silky-smooth control over channel level, pan or aux settings. Four encoders are also available for mix control, as well as transport and jog/shuttle controls. Stereo monitoring is included, and the FW-1082 even mixes signals internally for stand-alone use. 10-in/4-out audio interface at 96kHz/24-bit Nine 60mm touch-sensitive moving faders Four balanced XLR / 1/4" TRS mic/line inputs with phantom power Four balanced 1/4" TRS line inputs 1/4" TRS insert jacks for channels 1 & 2 S/PDIF stereo digital input and output Balanced 1/4" TRS monitor outputs Headphone output with level control Two MIDI inputs and outputs Assignable Footswitch jack Eight channel strips with solo, mute, select, record arm indicator Four assignable encoders control pan, aux level and EQ parameters Transport controls, jog/shuttle wheel, and many other surface controls Emulates Mackie HUI and Mackie Control in addition to the included native mode control plug ins Includes GigaStudio 3 LE Includes Steinberg Cubase LE 48-track 96kHz workstation software
Tascam US-2400	Tascam US-2400 Now you can use your mouse for what it’s good at and use a control surface for what it’s good at: hands-on mixing with lots of real faders, knobs & buttons. The TASCAM US-2400 is the first DAW fader controller with enough faders to handle a typical recording session — and feel like a real mixing console — without lots of bank switching. The US-2400 features 25 touch-sensitive moving channel faders and a touch-sensitive motorized master fader, each with 10-bit resolution for precise level control. Each channel has dedicated select, solo and mute controls. Twenty-four rotary encoders are provided, selectable to control pan or up to 8 aux sends. Plus, all 24 encoders standard MIDI controller messages for control of plug-in parameters. Each encoder has a ring of LEDs that can display the current setting or double as channel meters during recording and playback. A set of solid-feeling transport buttons are also provided, as well as a shuttle wheel and a joystick for surround panning. Compare it to any other controller on the market today (and the extra expanders you’d have to buy to get 24 motorized faders) and you’ll discover that the US-2400 gives you more control for the money. Fully-mapped control for Pro Tools, Sonar, Cubase, Nuendo, Logic and Digital Performer Twenty-five touch sensitive 100mm moving faders, each with 10-bit resolution Select, Solo and Mute keys 24 encoders control pan, aux level or channel strip functions like EQ & Aux LED ring displays around encoders display parameters or channel meters Footswitch jack for punch-ins Fader bank switching and In/Out point buttons Assignable Function keys can be set to Autopunch, Record arming, Undo, etc. Solid-feeling transport controls Smooth Jog/Shuttle wheel Compatibility with leading DAW applications like Pro Tools, Logic, Sonar, Cubase, Nuendo, Digital Performer,

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