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Yamaha SW1000XG EQ Response

PC Notes By Martin Walker

We take a look at the EQ response of the SW1000XG soundcard, the possibility of disabling the SMBus to gain an extra IRQ, and more advice on managing your updates.

In last month's PC Musician I looked at using RightMark's Audio Analyser for basic soundcard testing, although I've also been finding it useful to help make the response of my Yamaha SW1000XG soundcard flatter. I provided modified values for the five-band EQ that forms part of Yamaha's custom SWP30 chip in SOS November 2000, and this sits near the end of the signal chain on not only the SW1000XG soundcard, but also the MU100, MU128, the A3000/4000/5000 samplers, and various other Yamaha synths. Its five bands have presets labelled Flat, Jazz, Pops, Rock, and Classic, but unfortunately the Flat preset doesn't live up to its name in the SW1000XG, giving a noticeably warm response due to almost 2dB of boost at 40Hz, and about 1dB of extra 'air' at 10kHz due to subsequent EQ tailoring.

Here are the frequency responses for the SW1000XG in its default state as reported by RightMark's Audio Analyser 4.0, with my previously published settings for a flatter response, the new tweaked Q setting and through the Kenton Plugstation.Here are the frequency responses for the SW1000XG in its default state as reported by RightMark's Audio Analyser 4.0, with my previously published settings for a flatter response, the new tweaked Q setting and through the Kenton Plugstation.Sadly, you can't flatten this out by simply applying 2dB and 1dB of cut at 40Hz and 10kHz respectively since the five-band EQ curves are completely different. Previously, I've managed to come up with some adjusted settings that provide a significantly flatter response by using a special set of test tones and a spectrum analyser plug-in, but I've managed to flatten this response further with the aid of Audio Analyser. As you can see from the screenshot in figure one, the new settings give a noticeable improvement in flatness to within +0.25/-0.35dB between 10Hz and 12kHz, although the audio improvements are admittedly subtle.

To achieve this new response, you need the following settings: band one and five remain unaltered, while band two has 1dB of boost at its default 500Hz frequency; band three has 1dB of boost at 1kHz and band 4 has 2dB of boost at its default 4.0kHz, with a lower Q setting of 0.4. However, there's another advantage of using these settings as Yamaha reduce the internal digital level by 6dB before it reaches the output effects and EQ section to allow some headroom. This has annoyed quite a few musicians who find the final output level lower than expected, and therefore not making the best use of the available dynamic range. So in addition to flattening out the response, my settings raise the overall level by around 2dB, which improves this situation a little, and yes, I did try to find some EQ settings that raised overall level by around 6dB overall, but it proved impossible to simultaneously keep a flat response.

Just to prove that the tailoring is completely separate from the five-band EQ, the screenshot also shows the result when you replay SW1000XG sounds through Kenton's Plugstation. The five-band controls are still all 'in circuit', but this time the default Flat preset is flat to within +0/-0.5dB over the entire audio range from 10Hz to 20kHz, emerging through 24-bit converters with noticeably less background noise.

Dungeon Buss

In the past I've looked at disabling unused serial and parallel ports, along with USB Universal Host Controllers, to regain some interrupts so that soundcards have a better chance of getting a dedicated IRQ. However, if you've ever investigated the IRQ list, you might have noticed a device in your IRQ listing containing the words 'SMBus Controller' and wondered what it does. The System Management Buss is a two-wire interface that enables system and power management related chips to communicate with the rest of the system. Originally conceived by Intel, the SMBus is intended for so-called 'Smart Batteries' that haveembedded electronics to hold data, measure the batteries' current state, and calculate and predict the batteries' future performance. So the SMBus itself provides the protocol to transfer information to and from a host device such as a laptop PC.

Yamaha SW1000XG EQ ResponseAt this point, most non-laptop users might be thinking about disabling the SMBus Controller by using the 'Disable in this hardware profile' option inside Device Manager to gain an IRQ. But I subsequently discovered that the SMBus can also be used for modern memory chips with EEPROM data, and for hardware monitoring devices that provide readouts of useful parameters like CPU and motherboard temperatures. However, apart from utilities like SiSoftware's Sandra and motherboard monitors, such functions are mainly used within the realm of the BIOS, so I still doubt that Windows is likely to require the SMBus.

I haven't been able to find any reference on my Internet travels about the effects of disabling the SMBus so I tried this myself and haven't experienced any problems during a period of several weeks. So if you're short of IRQs, why not give this a try — let me know if anything untoward happens, or if you find a valid use of the SMBus by Windows running on non-battery-powered PCs.

One, Two, Three, Let's Manage Our Updates

Following on from last month's advice about installing updates, I thought I'd share some more tips this month about update managing and organising. First of all, when you install multiple versions of an application on a multiboot system, streamlining the process will make your life much easier, and one thing I've done that's saved a lot of head-scratching is to create two folders called 'PC Updates' (for operating system and general application updates), and 'Music Updates'. Both are on a data partition that's visible to each operating system I select from my Boot Magic utility, so that I can access their contents on a universal basis.

If you organise your update files carefully into folders by manufacturer, you'll never face having to download them again after they get mislaid.If you organise your update files carefully into folders by manufacturer, you'll never face having to download them again after they get mislaid.Inside these two are further folders arranged by manufacturer's name, and inside these... yet more folders, one for each product. Any update files that I download over the Net automatically go into a 'Net Downloads' folder on the same partition, and then I move them into the appropriate updates folder. I also copy various application INI files that contain settings and presets into each folder, which are all real life-savers when you buy a new PC or create a new music partition. Every file you need to bring your applications up to their latest revision, along with your own presets and settings, becomes really easy to find.

A further refinement is to create a file named 'passwords and serial numbers.txt' using Notepad. Stored in the root folder of my 'Music Updates' section, this contains the name of each application, the latest version number downloaded, along with any relevant serial number, password, and other details required during installation. Each time you install a new application or utility, just jot down its details here, and when you next need to install it again you'll never end up trying to remember whether the serial number you need was on a label stuck to the box, written inside the printed manual, on a loose sheet that's since got lost or, worst of all, in an email received in response to a shareware payment or challenge/response situation that's now AWOL.

This text file has even saved me re-downloading updates that I've already got — it's sometimes easy to forget your latest version number and end up thinking something new is available from the manufacturer's web site, which brings me back to having obvious release dates near download files...

Hoax Emails

I often receive emails warning me of vicious virus programs on the loose that threaten to wipe my hard drive and reduce my CPU to a smoking ruin. Sadly, while it's bad enough that otherwise talented programmers waste their time creating such malicious code, plenty of other people seem to get their jollies by simply spreading false rumours. Hoping to cause as much disruption as possible, they often throw suspicion on perfectly valid system files, suggesting that you delete them immediately if you find them on your hard drive.

Such hoaxes waste people's time, but thankfully there are now web sites that you can visit to minimise your disruption. Symantec have an excellent reputation for their AntiVirus programs, but they also maintain a page with details of known hoax emails. A second page contains a list of known joke programs, which cause no harm but do strange things to your PC, such as wobbling your windows or causing objects to fly about. So if you receive an email from a friend warning you of the latest computer virus, or something peculiar happens to your PC, take a look at Symantec's security response page at:, and take a look at both the hoaxes and jokes pages in its reference area before doing anything rash.

PC Snippets

While you can use Regedit to manually edit the Windows XP Registry to change various aspects of Windows' performance, it's generally much safer and easier to use a dedicated utility like Tweak UI from Microsoft's free Windows XP Power Toys. This provides plenty of ways to improve various aspects of the user interface, such as speeding up menu opening, disabling various auto-run options, and removing the ridiculous animated search puppy. However, Tweak XP Pro from Totalidea Software lets you configure system elements to much finer degree. Aside from the ability to tweak many hidden Windows settings and a system optimisation wizard to fine-tune your PC's performance, version 2.0 adds Registry Cleaner, DiscDrive Doctor, Clear Type Configuration, BIOS Information and more. In all, Tweak XP Pro contains 37 different utilities, and while some of the graphic, animated, and skin options won't appeal to musicians who want to streamline their systems, most should prove very useful. You can download a free 2.3MB trial version, but the full version is just $29.95.

RightMark's Audio Analyser is now up to version 4.0 and, as I reported using the beta version in last month's PC Musician, this provides better stability, faster testing and more accurate results. It also provides an easy way to compare up to four sets of results (see SW1000XG screenshot), in addition to supporting new 24-bit, 32-bit, and 192kHz format options. A new asynchronous mode enables you to test non real-time devices such as DAT and CD players by generating a WAV file that you can subsequently replay on the test device, record the results and analyse using Audio Analyser. The user manual has also been updated, and it's still freeware — well done to authors Alexey Lukin and Maxim Liadov.

After a year's wait, Yamaha have finally released official dedicated drivers for use with their SW1000XG and DS2416 (DSP Factory) cards when running under Windows XP. The 2MB update provides 32-bit ASIO support for Acid 5.0, Cubase SX and Logic Audio, plus WDM KS support for Sonar 2.0. It fixes various 'blue screen of death' problems experienced by a few musicians using the previous Windows 2000 drivers, in addition to ASIO problems with Reaktor and Reason, and various issues with Logic 5 and Microsoft's internal Windows synth. After running Sonar 2.0's Wave Profiler, I managed to achieve a reported latency of 2.9ms, although, as I fully expected, the 1K hardware flip buffer is still in circuit. Using my real world MIDI-to-Audio latency technique, I measured an overall value of about 28ms, which includes about 23ms for the flip buffer.

PSP have updated their versatile PSP42 plug-in, which is modeled on Lexicon's famous PCM42 rackmount unit. Version 1.1 cures a few bugs including a feedback problem that used to occur after several minutes of continuous operation, while the interpolation algorithm has been improved. Meanwhile, Pentium 4 users will be pleased that new optimisation now cuts their CPU overhead to half of version 1.0, and Logic Control users also get increased support.

Published December 2002