PC users can now enjoy Native Instruments' Absynth.

Choosing the right processor is essential for computer-based musicians relying on native processing, especially when it affects the quality of reverb plug-ins that can be used.

During my Internet travels this month I came across an intriguing web site at www.theabcd.com. Steve Carr of Hit And Run Studios has recorded many famous acts such as Faith Hill and Nils Lofgren, and in his spare time during the last five years he's been compiling a CD of A/B comparisons to let musicians hear the real-world difference between recordings made using analogue and digital equipment. Among the comparisons are mixes made using Mackie analogue and Yamaha 02R digital mixers, signals processed through solid-state preamps and compressors versus their tube equivalents, and a miked Marshall stack compared with a Line 6 Pod. However, Steve has gone one step further and also included tracks to illustrate the results of using different types of cable, the same part played by different musicians, and even by the same musician performing on different days.

As you might expect, the results are fascinating and I hope to get a copy of the CD, which costs just $34.95, for further study. There are also a few MP3 examples on the web site to download: one that particularly attracted my interest was a comparison recording of a Lexicon PCM70 Concert Hall reverb and the Waves Trueverb plug-in, using an edited version of its Concert Hall patch. You have to buy the CD to find out which is which, but it got me thinking about comparisons that crop up time and time again for PC users.

Which processor to use as the basis of your music PC is still a hotly debated topic, and the situation is constantly changing as AMD and Intel release new designs and make existing models available in faster clock speeds. Even if you have an unlimited budget, it's still difficult to determine which cutting-edge model will provide the fastest performance with music software. The situation is further complicated as prices of older and slower models shift ever downwards, while relative audio software performance fluctuates as developers finally get around to incorporating optimisations for specific chips.

It seems to be generally accepted that for digital audio processing, the AMD Athlon range provides excellent floating-point performance that exceeds the level given by Intel Pentium 4 chips of roughly equivalent clock speeds by a significant margin. Athlons are also noticeably cheaper. However, due to the various issues with associated motherboard chipsets that I discussed in SOS August 2001, buying an Athlon-based PC can sometimes trip you up unless you're aware of all the potential pitfalls. The majority of such problems seem to be connected with early Via chipsets, and most musicians seem to be getting excellent results with new motherboards such as those manufactured by Asus.

CS1x Background Edit may be just the utility that Yamaha CS1x users have been looking for to get more from their synth.

Another issue to consider is that many AMD processors generate more heat than equivalent Intel models, and although for general use this shouldn't worry many people, for musicians it raises the issue of more powerful (and therefore noisier) cooling fans. Many AMD Athlons run at over 50 degrees Centigrade, even with special heatsinks and fans, while an equivalent Intel Pentium 4 may run at between 30 and 40 degrees with a standard Intel cooler.

My current Pentium III 1GHz PC runs so cool that I've disabled all three fans in my Lian-Li PC60 case, leaving only the whisper-quiet Zalman CPU fan and Quiet PC PSU fan active, and the CPU temperature still generally sits at about 45 degrees. I have heard of Athlon XP users achieving CPU temperatures of between 49 and 52 degrees with the same number of fans, but this appears to be less common. No doubt AMD will soon launch a new range of processors that run significantly cooler, but in the meantime, bear this factor in mind when deciding which processor to include in your next music PC.

The stability of your PC shouldn't be affected by your choice of processor, since this is more likely to be determined by your choice of Windows platform (XP seems to be the current favourite), how it's been set up, your soundcard and other hardware drivers, and your choice of software applications. I don't include overclocked systems in this comparison. If you indulge in overclocking then all stability bets are off whichever processor you choose, although if you know what you're doing, and take all the necessary precautions with some thorough testing afterwards, it's still possible to achieve remarkable improvements with some processor models.

One thing even staunch Intel supporters can thank AMD for, however, is the Intel price drops brought about by their competition.

The quality of PC reverbs is intimately connected with processor performance and optimisations. Some, such as the Wave Arts MasterverbDX I reviewed in February 2002's issue (www.wavearts.com), are sold on their low CPU overhead. This certainly achieves its aim, taking just 2.3 percent of my Pentium III 1GHz processor, but barring a revolutionary new approach, creating a better-sounding reverb will always take more processing power. Waves' Renaissance Reverb (www.waves.com) takes five times as much power (11.4 percent) on my PC and does sound significantly smoother, in addition to offering many more parameters. A more extreme example is Sonic Timeworks' ReverbX (www.sonictimeworks.com), which on some settings can consume all my processing power in one gulp. Sonic Timeworks recommend a minimum of a 900MHz processor, or a dual-processor system.

Developers obviously tailor processor overheads to suit the target market, and an example of this is TC Works' Native Reverb, a popular product that sounds as good as it looks. But when I got the chance to try out the TC Reverb that runs on Soundscape's Mixtreme soundcard, it was in a different league, being noticeably smoother and denser, largely because it runs on DSP chips that don't occupy the native processor and can safely demand more 'juice'. This same increase in sound quality is the main reason why DSP expansion boards supporting so-called 'powered' plug-ins, such as TC's Powercore and Universal Audio's UAD1, have proved so popular.

However, the choice of CPU can make a significant difference to reverb performance for those of us who rely on native processing. Unlike most other plug-ins, reverbs carry on processing the same audio data for the length of the decay time, and so the amount of data that can be held inside the processor, determined by its internal cache size, becomes far more significant.

It can also make a big difference whether the music application and plug-ins you're running have been optimised for your processor. Many now detect which one is installed and use different code accordingly, which can lower CPU overheads considerably. The extra SSE instructions supported by the Pentium III, Pentium 4 and AMD Athlon XP/MP ranges are the most popular optimisation, but at present, little software specifically supports the SSE2 instructions of the P4, which holds back the chip's top performance.

However, since these optimisations get added at various times, often as part of routine updates, it's very difficult to provide hard and fast answers on reverb overheads. For instance, when I reviewed the 1.7GHz P4-powered PC from Millennium in the January 2002 issue, Waves' Renaissance Reverb version 3.2.1 (with SSE but no SSE2 optimisations) consumed just 7.7 percent of the CPU, whereas previous versions using the same combintion required 22 percent. The moral of the story? It's important to check plug-in version numbers when making performance comparisons.

PC Snippets     The long wait for the Windows version of Native Instruments' Absynth is over and has been followed by a minor 1.3.2 update, which is available as a free 4.8MB download from NI's web site. Up to eight DXi instances of the semi-modular soft synth can now run inside Sonar, and the new recorder window lets you capture a 10-minute performance with overdubs. A new option to open 'One window at a time' reduces clutter when editing, while all of the effects can now be tempo-sync'ed and you can extract the initial 1024 bytes from any WAV file to use as an internal waveform. Program Changes can now be automated in both DXi and VST Instruments, and other smaller improvements include drag-and-drop bank files, new keyboard shortcuts and the ability to export preset names to the clipboard. www.native-instruments.de Yamaha's OPT (Open Plug-in Technology) standard is beginning to attract shareware developers and Chris Share of CPS Software has released CS1x Background Edit, an easy-to-use utility that lets you edit the background channels five to 16 of Yamaha's CS1x control synth. This overcomes the front-panel restriction of only being able to access four MIDI channels when in performance mode. It has voice and parameter editing sections, and all of the internal waveforms are available, including the 'secret' QS300 bank. The utility costs just $20 to register and is available in both a stand-alone version, which runs on Windows 95, 98 and 2000, and an OPT version, requiring an OPT-capable host such as Sonar 2. www.labyrinth.net.au/~cpsmusic/ Nylon Fleta Guitar is the latest instrument to be added to the Ntonyx Pro Stereo sound library. Like previous instruments from this collection, the Nylon Fleta has various presets with up to seven performance layers and is available in both Giga and SoundFont formats for just $17.95. www.ntonyx.com