DIGITAL HOME RECORDING STUDIO

Today the digital technology of the sound processing is rapidly supplanting analog systems in recording studios. Computers have become commonplace in audiophile society. The next step in the sound recording development will be the total virtualization of recording studios.

Typical low and average budget recording studios of 1980-1990th consisted of different musical instruments, microphones, analog preamplifiers and power amplifiers, speakers, monitors, a mixing console, multichannel type recorder and sound processing device.

The mixing console communicates signals from electronic musical instruments and microphone amplifiers to one or another device. It can regulate input/output levels, sum up signals from different devices and pass the result signals to the multichannel type recorder, digital recorder and monitors (and/or stereo telephones) via power amplifiers. An ordinary not very expensive mixing console has 24 separate inputs, 8-24-channel signals` parameters control, 16-24 linear outputs. Modern digital multichannel type recorders enable the recording of 16-48 tracks of 24-bit audio 48 kHz. Effects processors are represented by analog-digital reverbs, delays, choruses, compressors, expanders, noise gates, equalizers and so.

Guitar sound processing is a special theme. In this case the sound should not be polished but created. It is well known that a direct hard disk recording from guitar`s pickups gives a flat, poor sound. It can not be compared with what you hear on the famous musicians` concerts or CDs. You need a whole bunch of analog and digital-analog devices to make a professional guitar sound in a studio. An audio signal goes to a tube preamplifier, then to a transistor (or tube) distortion, sustain, compressor, equalizer, after that to a guitar effects processor, tube power amplifier and speakers. A guitar speakers` sound turns into electric signals by microphones. Finally it goes to a mixing console, monitors and a type recorder.

Let us take a device DA7 by Panasonic as an example of a modern digital-analog mixing console. It has 16 channels. Out of them 8 channels are high quality microphone preamplifiers with XLR connectors and fantom power supply. I have never seen such equipment in the sound cards for PC until now! There are 16 digital inputs/outputs for digital type recorders or sound cards like Turtle Beach Pinnacle or SBLive. Digital data can be of AES/EBU or S/PDIF formats. A powerful 32-bit processor enables to control and process signal in real time. Such effects as equalizer, compressor, reverb and chorus are available. Signal delay between inputs and outputs of DA7 is 2,5 ms (compare with 20-30 ms usual for many Windows program modules). A rather large LC display of the mixing console will sure catch your eyes. It makes DA7 looking like a huge laptop or a notebook with numerous buttons instead of a keyboard. There is no mouse but you can use something like a trackball.

They are not Windows NT computers as you might expect. A special class of such devices exists and develops in the studios (I wonder who uses them?). Let us have a look at one of them VS-1680 Multitrack Digital Workstation by Roland. It is somewhat a PC with its own homemade operation system (why they do not use Windows CE?). VS-1680 can boast of a powerful processor, excellent 20-bit 10-channel sound card , hard disc of large capacity and LC display. It is designed for recording, editing, mixing and mastering. There are 256 digital tracks in 16 folders (similar to WAV-files). A digital mixing console has 10 inputs (XLR with fantom power supply for microphones, jacks, S/PDIF) and 12 outputs. There is an 8-channel effects processor and 3-band equalizer. MIDI synchronization with external sequences is available. It is a pity but you can not connect the thing to Internet though the price of it is about $2400.

They are known as Digital Audio Workstations (DAW). Let us take for example SSHDR1 Plus by Soundscape. It provides such functions as digital multitrack recording/playing on an internal hard disc, real time sound processing while you make the sound-track of a TV show or montage a radio news issue, synchronization of the sound-track of a film with movements seen. There are 8 20-bit analog-digital/digital-analog convertors (ADC/DAC) by Crystal. Signal/noise ratio after ADC is 93 dB, after DAC - less then 112 dB. Unlike multitrack hard disk recorders, DAWs consist of two parts: part A - a hard disc recorder with a digital sound processor (DSP hardware) and part B - a PC-based control system usually working under Windows 95/98/NT. All digital signal processing and digital mixing is provided by the DSP hardware. Thus it does not depend on PC calculation power at all. You need at least a Windows computer 486DX2-66 mHz RAM 16 MB. Audio data in digital format are stored on the hard disc of part A though they can be moved to the hard disc of part B. Each of 10 channels (and all of them simultaneously) can be processed in real time with the following effects: equalizer, compression, reverb, chorus, flanger, noise suppression, pitch-shifter and time-stretch.

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Such systems integrate with PC hardware and interact tightly with Windows 95/98/NT operation system on the level of virtual drivers and a Graphic User Interface (GUI) as well. Software-hardware sound processing systems consist of a multichannel sound card with DSP, drivers and GUI (usually under Windows 95/98). DSP or central processing unit (CPU, usually Intel Pentium) realizes sound processing. Though it can be done by DSP and CPU simultaneously. Audio data in digital format are stored on the PC hard disc as a regular file. SBLive! (Creative Technology, Ltd.), Montego A3Dxstream (Tuttle Beach Systems), Sound Track 128 DDMA Ruby (Hoontech), Guillemont Maxi Sound Dynamic 3D (Guillemont International) sound cards can be classified as software-hardware sound processing systems. But many musicians using PC for their recording projects prefer to deal with the sound processing systems based on Session8 (Digidesing, ISA) or Pulsar (Creamware, PCI). Let us have a look at the latter. Pulsar hardware has two ADAT-inputs and two ADAT-outputs, 2 24-bit (!) ADC, 2 20-bit DAC with 96 kHz sampling frequency, an analog 20-bit mixer, MIDI interface, 4 powerful 32-bit DSP SHARC by Analog Device (on sound processing tasks calculation power of each one can be compared with that of Pentium III - 500 MHz), a connection to PCI. Software consists of the drivers for Windows and CUBASE VST (ASIO-drivers), a virtual 32-channel mixing board (GUI under Windows 95/98/NT). The last provides control over hardware and adding sound effects like reverb, chorus, flanger, equalizer, exciter, compression/expander, noise suppression. A sound can be processed by DSP or CPU software. A combination of software and hardware processing is possible. In my point of view GUI made as a usual Windows software is too real. My eyes used to the standard Windows GUI elements were soon bored with numerous carefully drawn little handles, connection cables, switches and so.

Virtual sound processing systems are meant for engineers who care about a high quality sound but have no enough money… they are the majority now. PC used in conjunction with a multichannel sound card (or several stereo sound cards) can substitute a mixing console, sound processing devices and a multichannel type recorder. A sound recording system based on PC is free of jitter (look at the article about ADC/DAC). This is its obvious advantage.

The quality of software effects is different. For instance, the software noise suppression works better than its hardware analogues. So, sometimes you have to use hardware studio devices to make a really good sound.

It is a tough problem to realize the software model of analogue guitar sound processing devices. In the analog recording studios they need a whole chain of analog and digital devices (DSP) to make a professional guitar sound: a tube preamplifier, transistor (or tube) distortion, sustain, compressor, equalizer, guitar effects processor, tube power amplifier, speakers, microphones, a mixing console, type recorder.

The software is better

It seems incredible but in some arrears of sound processing the software versions have overtaken their hardware studio analogues. That has its logical explanation. In the first place, Pentium III increasing calculation power makes possible software real time sound processing by skillfully made algorithms. Secondly, in the software industry a development cycle from an idea till a ready ware takes considerably less time and money than a similar process in the hardware industry. A software developer can generate ingenious algorithms while he should not care about "iron" ware. In the third place I would mention Windows GUI (graphical users interface) enabling the exclusive (using 3D-technologies) design of the software modules. (Though one must not expect a shareware to be as attractive). So it a pleasure to deal with them rather than with tiny LC displays of studio devices. And finally, some sound processing algorithms have been realized only as a software for PC such as ProSonic deconvolver (eliminating echo and reverberation out of an audio signal) and declicker (getting rid of "clicks" on the old vinil records). I have not yet met a hardware 8-channel 128-band studio equalizer! But you can easily make such a virtual device using N-Track shareware and a corresponding ActiveX plug-in. I have never heard about hardware mixing boards providing 3D-sound mixing of audio records. While 3D-sound technologies on PC is a step forward compared with a traditional stereo (3D Sound Example). Though you can charge it yourself…

Simanenkov Dmitry mailto:digital_sound@bigfoot.com

Next Part of Home recording - CD CREATION & SOUND IMPROVING

Creating Pro Guitar Sound on PC

Sound Compression - MP3 and others

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