Sound cards

While the benefits of running a top-quality video card and monitor are obvious to most consumers, the advantages of shelling out for a high-end sound card can be a little more nebulous. Be it listening to MP3s, recording music, or playing games, there's a soundcard for every application. This buying guide will explain to you the relevant soundcard technology, specs and must-know facts, ensuring, you make the right purchase decision.

Integrated sound


Integrated Sound

These days, just about every modern PC ships with some basic form of audio output integrated into the system. Audio processors have been widespread on motherboards since the mid 90s, and there's a good chance that the machine you're using now is relying on an integrated audio controller to output sounds. Integrated controllers are widely employed because they're relatively inexpensive to add to a motherboard and suffice for less-discerning users. Generally, the sound provided by these processors is adequate for system alerts or use in an office environment, but falls down for serious gaming, music or DVD playback for a couple of reasons.

Motherboard with onboard sound

The first is sound quality. While current integrated solutions offer impressive integrated sound on paper, the audio processors and associated wiring are built into the motherboard. As motherboards feature thousands of wires packed very close together, the current flowing down one wire often affects the current flowing down another. As a result, interference is common, which shows up as background noise in the audio signal. This tends to mean lots of pops, clicks, and buzzing can appear in output sound. The balance of signal and background noise is quoted as a signal to noise ratio (SNR), which is measured in decibels (dB). If a motherboard features a high signal to noise ratio. of around 100dB) , the listener can expect a clean, clear signal devoid of any background pops, clicks or buzzing. A low signal to noise ratio (below 90dB) will mean that audio signal will be affected by interference.

PCs that have motherboards based on the Intel 915/925, Intel 945/955 and NVIDIA nForce4 chipsets, for example, all have exceptional sound capabilities using the Realtek ALC850 codec (coder/decoder). This codec supports up to eight speaker channels, up to 16-bit resolution and has a signal to noise ratio of 100dB (decibels), which means the chip does not produce a lot of background noise that can colour the audio signal. Motherboards with this chip can be used comfortably for audio creation and editing.

Some older motherboards and some that are geared towards the entry-level market feature audio chips from C-Media, which can have signal-to-noise ratios below 90dB, and may not be suitable for those of you who want to work intensely with audio.

The second reason you may not want to use an integrated sound controller is the fact that they rely on the CPU to process the sound, which can slow a system down slightly. This isn't a concern for most users as the CPU impact is extremely small, but serious gamers and video editors want to keep the processor as free as possible to ensure all system resources are allocated to driving software.

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The sound card


The Sound card

Audigy Sound Card

As the name suggests, a sound card is a piece of hardware dedicated to outputting audio from a computer. Conventional stand-alone sound cards are designed to replace integrated solutions and boost audio quality for listeners. A wide range of sound cards exist to suit different uses, and are available as either internal cards designed to plug into a computer motherboard, or as external boxes that can be connected to a USB, PC Card or Firewire port.

Sound cards include dedicated chips that process the audio directly, which frees up the CPU to focus on running other applications. Internal sound cards plug into the motherboard but are a little distance from the main motherboard circuitry. As such, they tend to feature higher signal to noise ratios than their integrated counterparts. Some even include dedicated shielding, which helps reduce the interference generated by the motherboard. What all sound cards have in common is a chip designed to convert digital signals into analogue ones that can be piped to an amplifier or headphones. Current models also include digital and optical outputs that enable them to be connected directly to surround-sound amplifiers.


A little history

Prior to the early 90s, PCs had little capacity to output sound beyond basic beeps. The sound card was popularised by Creative Labs (www.creative.com.au) at the start of the 90s with its range of Sound Blaster products.

The SoundBlaster became a de facto standard for amateur audiophiles, gamers, and home users, and was quickly emulated by other hardware manufacturers. The SoundBlaster originally shipped as a monophonic card, but this quickly moved to stereo output, before Creative focused on improving sound quality. The product line has continued to evolve, but other manufacturers have caught up. Today, Creative doesn't dictate the direction of the market, though it still offers a comprehensive range of audio products, competing with brands such as Terratec, AOpen, Hercules, Philips, M-Audio and many others moving right up into professional high-end models.

The card itself


The Card Itself

Sound cards are available as either internal PCI (or PC Card for notebooks) cards or external boxes. Generally an internal sound card is the way to go for a desktop PC as external solutions tend to carry a price premium. External models benefit from being easier to install and are often the only solution for notebook users or those that don't want to mess around inside their systems. Entry-level external solutions start at around $55, and range up to around $300, while internal models range between $40 and $500 and up for professional high-end models.

Modern sound solutions offer an enormous range of inputs and outputs to suit just about every connection method available, from digital input and output, Optical, and S/PDIF (Sony/Philips Digital Interface). The latter is a connection found on many higher-end audio devices that allows digital signals to be sent from device to device without having to be converted to analogue. . Digital connections are used for outputting surround-sound signals to an amplifier, while optical and analogue S/PDIF can be used to input and output audio from the sound card to a compatible amplifier or speakers.

In fact, it's the range of inputs and outputs, as well as signal to noise ratio and interface that determine the price (and target market) of a sound card. As a basic rule of thumb, the more you pay for a sound card, the higher the signal to noise ratio. Some high-end sound solutions feature an external box as well as the internal card. This allows many extra connections to be made to the card simultaneously and provides space to fit external dials for EQ and volume.

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Jack sensing


Jack Sensing

Outputs on a sound card

Sound cards (and motherboards that can output in surround-sound audio) also feature a number of analogue Walkman-style (3.5mm) jacks at the rear of the card. These jacks generally comprise of headphone, line-out, line-in and microphone connectors. Many of these jacks can do double-duty by allowing the computer to adjust what they're used for (better known as jack sensing). Jack sensing, allows the sound card to automatically detect what's plugged into each port and assign the audio accordingly. For example, if you wanted to connect a set of headphones, a line-in and a microphone to these connectors, the computer would automatically detect what's there and assign each jack a function automatically. If they are to be used in a surround-sound configuration, the microphone port might be reassigned to handle rear-speaker output.

MIDI


MIDI

Just about all sound cards also include a MIDI (Musical Instrument Digital Interface) port on the rear of the card that also doubles as a joystick adaptor and some specialised sound cards also include a dedicated MIDI IN and OUT port - sometimes more than one of each. Many keyboards and digital music hardware devices use MIDI to communicate directly with a PC. It allows computer musicians to sequence music using the computer to store audio information.

Musicians looking at buying a sound card should check a sound card's drivers support ASIO (audio stream input output). If not, you'll get high latency - a delay between you pressing a MIDI keyboard key, software telling the sound card how to respond and the note being heard. This is a significant problem with multiple tracks, particularly when laying down a new tune while listening to recordings. ASIO speeds up communication so sounds occur exactly when they should; ASIO 2 reduces latency still further. Your PC's performance will also affect latency, but as a rule of thumb for a music-orientated sound card, a rating of 5ms or less is what you should aim for.

Duplexing


Duplexing

One point to watch out for if you're interested in home recording or realtime chatting is duplexing (the ability to record/and or input and play back sound simultaneously). These days, just about all mid to high-end sound card features full-duplex capabilities, meaning they can both play back data and record at the same time or play audio from multiple programs simultaneously. Watch out for any cards that offer half-duplex operation, as they are limited to performing one function at a time, making VoIP conversation or serious recording impossible.

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Working through the numbers


Working Through the Numbers

Sound card manufacturers will generally list screeds of technical information with their products, but this detail can help choose a card to fit your needs. The key points to look for after assessing your connection method (internal or external), and desired connectors are bit and sampling rates, audio channels and signal to noise ratio.

Channels


Channels

First up, before worrying about signal to noise ratio and bit and sampling rates, you'll have to decide how many channels you'll need. A "channel" refers to the number of discrete speakers supported by the sound card.

A base minimum these days is support for 5.1-channel surround-sound audio (covering two rear speakers, two front speakers, one centre speaker, and one sub-woofer), though 7.1-channel surround-sound audio is becoming popular (this standard includes all the speaker positions defined in 5.1, with the addition of left and right middle speakers). If you're only going to rely on headphones for audio playback, the channel support is a non-issue, but this is crucial if you're going to play back through a surround-sound speaker set or an amplifier.

Sampling rates


Sampling Rates

Sound cards are generally marketed by supported bit rates and sampling rates, which refer to the maximum amount of sound data that the sound card can process per second.

Computers have no way of storing a continuous sound, so audio recorded into a computer is broken up into very small chunks. These small chunks are referred to as sample rate, which is a measure of audio resolution. For example, CDs are sampled at 44.1KHz (or 44100Hz), meaning there are 44100 chunks of sound stored for each second of audio. These discrete chunks are played back very quickly and the human ear recognises it as a sound. This is similar to the way a television works: it shows enough information each second to fool the eye into thinking it's watching moving pictures.

The higher the sample rate for a sound card, the "smoother" the sound, and the closer the digital recording resembles the original analogue sound.

The bit rate of a sound card refers to the amount of information stored in each individual chunk of sound. Bit rate and sampling rate go hand-in-hand and the higher the bit rate, the more accurate the digital recording.

CDs are recorded in 16-bit with a sampling rate of 44.1KHz, so any card with base specifications above that will be able to handle CD-quality playback. If you're just playing back MP3s, playing the occasional game, and covering system alerts, you can get away with a relatively basic card with 16-bit support and a 48KHz sampling rate. Keep a close eye on signal to noise ratio specifications on low-end cards, as this can be a major point of differentiation between models. These basic cards will set you back around $40-80.

If you're into watching DVDs and own a surround-sound amplifier, you're best off opting for a mid-range card with 24-bit support and a 96KHz sampling rate. These cards will generally cost around $200 and offer a signal to noise ratio around 85dB.

Finally, if you want to start producing your own music or take your DVD-watching very seriously, it's time to step up to a bells-and-whistles card with 24-bit support and a sampling rate of 192KHz. These top-of-the-line consumer solutions will offer a signal to noise ratio in excess of 110dB and are ideal for recording music live. Many also ship with external connection boxes and retail at around $500.

Speakers


Speakers

Computer Speakers

Of course, a sound card is only half the battle when it comes to setting your PC up for serious sound. After all, you still need to get the sound from the audio connectors to the airwaves. For best results, focus on buying a speaker combination that matches the audio output from your sound card. For instance, buying a 5.1-channel surround-sound speaker system to use with a 7.1-channel card means that you'll miss out on hearing two audio channels during playback. Shop around and demand information on each speaker in a multi-speaker kit, as total output figures can be misleading. Many speaker companies advertise "total output" across the speakers, but this could mean that the majority of the power is going to driving a huge subwoofer, with little attention paid to satellite speakers.

Last but not least, cast an eye over the list of software bundled with a sound card. Some basic solutions will offer little more than a driver CD, while some more expensive models may include games, music sequencing software and some troubleshooting tools. This can often be a differentiator between products with similar pricing and specifications: if in doubt, go for the card with the stronger software set. If software is irrelevant to your buying decision, hunt around for shops that are offering OEM or value bundles on hardware, as it often means you can get the card without bundled extras to save a little cash.

For more information on sound cards and other audio topics, go to PC World's Digital music section

This guide was last updated June 2005