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Tue 2 Sep 2008 04:00 AM

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Sounding off on PC audio

Windows details everything you wanted to know about speaker sets, sound standards and we even put four of the latest two-channel speakers to the test.

Windows details everything you wanted to know about speaker sets, sound standards and we even put four of the latest two-channel speakers to the test.

At its very core a ‘speaker' is an electromechanical transducer device that converts the electrical signals it receives from a source device - such as a DVD player or a PC's sound card - into the audio that reaches our ears.

A speaker will generally, depending on the cost, contain a number of ‘drivers' that are usually round in shape and these are made from paper, plastic and metal.

It is these drivers that are actually responsible for creating the sound we hear and there are a number of different types of drivers, each designed to tackle certain audio frequency ranges.

‘Subwoofers' are drivers that are designed to produce very low frequency sounds, ‘woofers' handle standard low frequency audio, ‘mid-range' drivers take care of middle frequencies whereas ‘tweeters' are setup to handle high-frequency audio.

In some cases high-end speakers also employ ‘super-tweeters' and these are specifically engineered for sounds that are outside a regular tweeter's frequency range.

A quality speaker generally employs each of these drivers in order to produce the most accurate audio whilst being able to run at high sound-pressure or volume levels.

Speakers that use a combination of drivers have an internal filter setup, so the electrical signals from the source are sent to the right driver. This filter is known as a ‘crossover'. Crossovers can be either passive or active.

A passive crossover is an electronic circuit that uses resistors, inductors and non-polar capacitors. These components form a network and are placed in between the amplifier and the speaker's drivers so that they can divide the signal into the relevant frequency bands and supply the signal to each driver. These crossovers function without any additional power and are regularly installed within a speaker's cabinet.

An active crossover is an electronic filter circuit that divides the source electrical signal into individual frequency bands before it is amplified. As a result, an amplifier is needed for each individual driver.

Active crossovers require external power but in terms of advantages these offer more precise frequency separation and are capable of serving high output purposes. Passive crossovers convert some of the source signal into heat when they function and are thus not the best choice for high power output satellite speakers.

Low-cost speakers forgo using the drivers mentioned above and instead use a different driver entirely. These are known as ‘full range drivers' and as the name suggests, these are designed to handle a wide range of audio frequencies.

These are mostly designed to produce clean output at low volumes but speakers equipped with this type of driver cannot compete with multiple driver speakers in terms of sound quality and accurateness. Speakers with full range drivers also lack a built-in crossover network as this is largely unnecessary since only a single driver is responsible for producing all the audio.

As a result, it is possible to produce this speaker type relatively inexpensively since a single driver is cheaper than several and the lack of a crossover network also helps to save cost.

The most basic speaker system you can buy is a 2-channel system. This will include left and right satellite speakers and is enough to produce basic audio. Most entry-level PC systems will ship with 2-channel audio systems. A 2.1-channel speaker set is superior to these because in addition to featuring left and right satellite speakers, a subwoofer is also present.

The subwoofer will enhance the overall quality of audio heard because it will handle low-frequency audio exclusively (if a proper crossover is in place).

Beyond these speaker configurations, you can also find surround configurations that are designed to envelop the user in audio. In its most basic form you could buy a 3-channel speaker system though these are now outdated.

This speaker configuration has two forward channels (left and right) and also includes a rear, centre speaker, which will be used to create surround effects. In this case the speakers should be placed an equal distance away from listener and in level with his ears.

For a better surround experience you can also opt for a 4- or 4.1-channel audio system (also known as quadraphonic). With the former you get four satellite speakers (two forward, two rear) whilst the latter also includes a subwoofer for better low frequency audio performance.

The most common speaker configuration type for high-end PC sound systems or even home theatre audio setups is 5.1-channel, which includes five satellites and a subwoofer. The satellites are separated to include three forwards (one left, one centre and one right) and a rear left and rear right. This speaker configuration can also be referred to as a 3-2 stereo system.

In recent years audio vendors have gone beyond 5.1-channel systems for homes and there are now 6.1-, 7.1-, 10.2- and even, at the ultra-high-end, 22.2 channel surround. 6.1 systems feature three forward satellite speakers, two ‘side' surround satellites, one rear satellite and a subwoofer. The side speakers in this sort of system are designed to be placed at the left and right side of the listener.

7.1-channel expands upon this further by including two rear speakers rather than just one. Whereas 6.1-channel systems haven't really taken off in the consumer market space, 7.1-channel speaker sets are becoming increasingly popular in homes.

10.2- and 22.2-systems are both very new to the market. A 10.2 audio system includes five forward satellites, five surround channels, two subwoofers and two ‘height channels'. In total the system offers 14-different audio channels.22.2-channel systems on the other hand are designed as the sound component for Ultra High Definition (UHD) content. This is an experimental HD standard that offers a video resolution of 7680 x 4320 pixels (compared to 1920 x 1080 pixels on 1080p Full HD).

In total this system uses no less than 24 speakers and has been demonstrated at international tradeshows in 2005 and 2006.

Strength in numbers

There are many different speaker setups available on the market and each offers different capabilities, so buying a speaker system largely depends on what type of sound you are interested in.

Speaker systems can comprise just standalone satellite or bookshelf-style speakers or can be a combination of one of the aforementioned speaker types and a separate subwoofer.

A subwoofer can be either active or passive in nature. Active subwoofers feature their own dedicated amplifiers and, depending on the model, allow for sound equalisation in terms of frequencies.

Passive woofers on the other hand lack an amplifier and rely on the strength of the source signal to produce audio. These subwoofers aren't as capable as active models in terms of clarity and power though their low cost means they are still widely used in budget home theatre systems.

Gigawatts of power

Creative's GigaWorks ProGamer G550W is a popular 5.1-channel audio system for PCs. It includes wireless rear speakers which receive audio signals from the system's amplifier via wireless connection.

The system offers 500-watts RMS of total power (70-watts per satellite and 150-watts from the subwoofer's 8-inch driver). Like most high-end computer speaker sets the G550W is THX certified and compatible with Dolby Digital and DTS surround sound technology.

Setting standards

For a proper surround sound experience, you'll need the right speaker setup, a surround-sound amplifier and, of course, content that is surround sound ready.

Just feeding your home theatre system a standard 2-channel stereo audio signal won't provide a real surround experience. In this case each speaker in the system will either play the same audio or only the front two channels will be used.

A number of different surround sound standards exist today and the most popular are Dolby Digital, DTS and THX.

Dolby Digital and DTS are different from THX however. Whereas the first two are actually multi-channel surround sound formats, THX is actually a quality assurance certification that hardware and content can receive. In other words, you can have films that are Dolby Digital or DTS sound compatible and are also THX rated.

The Dolby Digital brand name actually covers several different surround sound formats including Dolby Digital, Dolby Digital EX, Dolby Digital Live, Dolby Digital Surround EX, Dolby Digital Plus and, more recently, Dolby TrueHD.

Dolby Digital (DD), also known as AC-3, is the most common format of this technology and offers six different sound channels. Of these, five are rated for speakers with a frequency range of 20Hz to 20,000Hz whilst the last channel is reserved only for subwoofers and low frequency sounds (20Hz to 120Hz). The first film to use the DD sound format in cinemas was Batman Returns when it opened in 1992.

Dolby Digital EX (DDEX) is similar function wise to Dolby Pro-Logic and adds channel extensions to the standard DD format. Whereas DD is limited to six channels, EX includes support for up to eight discreet channels thus making it compatible with 6.1- and 7.1-speaker configurations. Dolby Digital Surround EX (DDSEX) is the cinema version of DDEX.

Dolby Digital Live (DDL) is designed for interactive content such as video games. It can be used to convert audio signals from games into Dolby Digital 5.1 format using a single S/PDIF audio cable. Competitor DTS offers a similar technology known as DTS Connect.

A number of sound card manufacturers include DDL support on their products including Auzentech, Asus, C-Media, HT Omega and Turtle Beach. Dolby Digital Plus (DDP), also known as E-AC-3, uses an enhanced coding system compared to standard DD. It supports up to 13.1-channel speaker systems, reduced audio artifacts and also higher data bitrate support of 6.144Mbits/sec.

Dolby TrueHD (DTHD) is one of Dolby's newest standards and is a mandatory inclusion for HD DVD hardware but is optional for Blu-ray kit. This format supports 24-bit, 96kHz audio channels and is capable of 14-channel audio support.

The Digital Theatre Systems or DTS format is much like DD in terms of what it can do and like DD, there are several variants available.

DTS 96/24 offers 5.1-channel speaker support using 24-bit, 96kHz audio signals. DTS-ES on the other hand comprises two variants; DTS-ES Matrix and DTS-ES Discrete 6.1. The former provides 5.1-channel audio whereas the latter 6.1- and 7.1-speaker support.

DTS NEO:6 is much like Dolby's Pro Logic IIx audio system in that it can also take stereo audio signals and convert them into 5.1- or 6.1-channel sound.

DTS-HD Master Audio is an advanced sound format that isn't limited to a set number of sound channels. The technology, previously known as DTS++ and DTS-HD, is an optional sound format for HD DVD and Blu-ray content and supports 24-bit, 192kHz audio.

DTS-HD High Resolution Audio like DTS-HD Master Audio is an extension to the original DTS sound format.

This format supports 96kHz, 24-bit audio signals and can deliver up to 7.1-channels of audio. It is an optional sound format that may be used by Blu-ray and HD DVD content.

DTS Connect is similar to Dolby Digital Live and is a two-part system. It is used to convert PC audio into DTS format using a single S/PDIF digital audio cable. The two parts comprising this system are DTS Interactive and DTS Neo:PC.

The former is a realtime encoder, which takes the PC's multi-channel audio and converts it into a DTS stream using a 1.5Mbit/sec bitrate. The latter is based on matrix surround technology and can convert standard stereo content into 7.1-channels though the resulting effect isn't an equal to true 7.1-channel content.

DTS Surround Sensation is perhaps the newest technology and is designed to create a virtual 5.1-channel experience using standard headphones.

With that out of the way, it's time to get on to the reviews. Thanks for THX

‘THX' is an abbreviation for Tomlinson Holman's eXperiment and was developed by Tomlinson at Lucasfilm in 1983. It is a quality assurance standard that makes sure that the sound produced by the sound system is as close to the sound originally recorded and mixed by the sound engineer. Star Wars: Return of the Jedi was the first film in cinemas with THX certification.

Philips SPA9300

Philips' SPA9300 2.1-channel speaker system is the least expensive here but you'd never know that just by looking at it. Finished in black and silver, the SPA9300 had the team won over with its stylish looks and design.

There's more value in store under the hood too because although they retail for just $81, the Philips system packs more power than the $190 Altec Lansing FX4021 system. Putting the system through its paces, we found that the SPA9300 performed reasonably well.

The satellite speakers boast good frequency response and are crisp in terms of audio delivery, so music tracks played at mid-level volumes sound decent. But the speakers aren't as adept in terms of movies and games, because slight distortions can be heard when you crank up the volume to immerse yourself.

Another problem that becomes evident when you start to explore the upper echelons of the volume knob is that the subwoofer drowns the satellites, so you get excessive bass, which ruins the overall listening experience.

The SPA9300 ships with a control pod that provides power and volume controls. The rear of the device also sports an audio input port so you can easily hook up your MP3 player and listen to tunes.

The system does provide bass control but perplexingly, the control for this sits on the subwoofer itself, which is rather inconvenient given that most people will hide this under their desk or table.

Creative GigaWorks T40

The Creative GigaWorks T40 speaker set distinguishes itself in this grouptest because it is the only speaker system that lacks a dedicated subwoofer. So whereas the other models here are all 2.1-systems, the Creative is actually a 2.0 set.

The T40 satellites are the tallest in the grouptest at 31cm high and stripping away the foam dust filters, you'll find a quality set of drivers.

Like the Logitech Z-2300 satellite speakers, the T40's uses 2.5" drivers to fire out mid-range frequencies and to make up for the lack of subwoofers, you'll find each has a ‘BasXPort' sitting atop. These are aimed at improving bass response.

The GigaWorks are designed very tastefully and are finished in a glossy gray colour scheme. The speaker's various controls such as volume, bass and treble all sit on the right satellite's front face so they're easily accessible. Another convenience is the headphone output port that sits just under the volume control.

In terms of performance, the T40 set performs admirably and with a surprising amount of punch considering the lack of a dedicated subwoofer.

That said, music and movies are the speaker's forte, games just don't have the kick because weapon fire and explosions don't have the bass to really make you feel the effects. That said the high quality drivers can provide crisp, clear sound even when cranked up to maximum volume.

Logitech Z-2300

The WinLabs team has never experienced an earthquake first hand but after testing Logitech's mental Z-2300 speaker set, the team is now quite certain they know exactly what it feels like.

This is all thanks to the Z-2300's super-sized subwoofer, which packs no less than 120-watts RMS of thumping power. When testing the Logitech's music playback capabilities the subwoofer rattled everything in its path that wasn't physically nailed down - particularly when listening to Blur's ‘Song 2' music track.

Switching to movies, the shells in Saving Private Ryan never seemed so real and playing FPS games such as Quake 4, explosions could be seen and felt.

The Logitech set isn't only a bass fest however, as the satellites deliver top notch audio that doesn't distort even near maximum volume; very impressive. As a whole then, the Z-2300s are easily better than anything else in this grouptest regardless of what you're using it for. Well deserving of the THX certification then.

The set ships with a wired remote control and happily, this includes volume, bass and power controls as well as a handy headphones output jack.

This inclusion of bass control means you won't have to worry about reaching for an impossible to find knob on the subwoofer, unlike the Philips SPA9300. The only thing we missed on this controller was ‘treble' control for the satellite speakers.

At $175 the Logitech system represent great value too, as the more expensive Altec Lansing FX4021 set isn't as powerful and just doesn't sound as great.

Altec Lansing FX4021

Retailing for US $190, the Altec Lansing FX4021 set has the dubious honour of being the most expensive 2.1-channel system in this grouptest. And, when you look under the skin, the FX4021 system just doesn't do enough to convince you that they're worth the price.

The 2.1 system is only capable of delivering a maximum power output of 46-watts RMS, which is the second lowest here. The only system with less power to brag about is Creative's GigaWorks T40 set and that lacks a subwoofer.

What makes matter worse is that Philips' SPA9300 speaker set offers more power and yet retails for less than half the Altec's price tag.

Putting the Altec Lansing set to the test, we found the system offered only reasonable performance, which is disappointed given the high price point. Like the Philips SPA9300, the FX4021 performs at its best at low- and medium-volume levels.

Here it's perfectly fine for listening to music tracks, watching movies or even playing games.

However, go above 50% on the volume control and things start to get ugly fast; the satellites provide muddy audio that lack clarity and punch. Thankfully, the system's subwoofer performs better; it delivers clear, thumping bass even when cranked to high volume levels.

This set does, however, score points with regards to convenience You get a wired and wireless remote control that give you control over overall volume, bass volume and treble. Editor's choice

Logitech's Z-2300

Logitech's Z-2300 speaker set is easily the best sounding and loudest in this grouptest and, as a result, had no trouble scooping up our Best Performance prize.

The Z-2300's incredible audio fidelity and earth shaking bass come courtesy of high quality drivers; the subwoofer sports an 8" driver whereas the satellite speakers boast a 2.5" mid-range driver each.

The satellites pack 40-watts of power output each and this is enough to fill even a medium sized room with sound, without needing to crank up the volume. That said, the Logitech's can handle full power too as our tests and tortured ear drums will attest to.

At a cost of $175, the Logitech system is also quite good value-for-money given that the more expensive Altec Lansing FX4021 speakers are more expensive and are nowhere as good.

Philips' SPA9300

Philips' SPA9300 speakers grabbed our Value prize cleanly because it simply offered the most bangs per buck.

Retailing for $81, the Philips is the lowest costing 2.1 system in this exam and yet it packs a mighty punch in terms of what you get for your money. For instance, you'll find the Philips subwoofer is more powerful than the subwoofer that's in the Altec Lansing FX4021 system and that set costs a cool $109 more than the Philips. Even the satellite speakers pack a strong punch; you'll find they're only 1-watt behind the Altec satellites in terms of power.

Beyond numbers, the Philips system did impress when it came to actual testing. At low- and mid-level volumes, they provide crystal clear audio and offer strong frequency response. The sub too provides enough boom, which ultimately makes this a very decent budget system.

How we tested...

Each of the speakers in this grouptest was hooked up to our ‘Paul' testbed's Creative Sound Blaster X-Fi sou-ndcard. This is one of the best audio cards on the market and ensured each of the speakers would receive a crystal clear audio signal. Each speaker system was connected in turn using standard analog audio cables, as none of the sets here featured digital inputs.

To test performance we fed each speaker set a movie (Air Force One), a selection of songs and the odd game or two. (F.E.A.R and Quake 4) In each case we tried the speakers at three different volume levels; low, medium and high.

We listened in closely to check whether the speakers were producing audio cleanly and also listened in to see if their frequency response and crossover was spot on. Speakers that produced crystal clear audio at all three volume levels and proved adept at handling a range of frequencies walked away with higher performance scores.

Feature scores were awarded based on just that, a speaker's various features. If a speaker system offered a remote control, separate audio adapter to hook up to multiple sources or even a headphones port, it walked away with a better score than a model that lacked one or all of these.

Value-wise, speakers that offered great performance and features for what we thought was a fair price were scored higher than expensive and underperforming systems.

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