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COMPUTER BITS BY JASON COLE The ins & outs of sound cards Sound cards have been around for quite some time and have improved from the mono 8-bit sound card up to the stereo 64bit sound card with 3D enhancement. Sound cards can also handle MIDI (Musical Instrument Direct Input). With the increased use of sound on the Web and better quality sound effects in games, sound cards have become more important than before and, at the same time, more complex. A sound card also lets you listen to CDs and audio files and allows you to record sound signals fed in via the line input socket or via a microphone connected to the microphone input. Most sound cards come with five The Line Out socket delivers audio signals at line output voltages. Any sound produced by the sound card is made available at this connector and is in the order of 1V, which is generally the standard for line outputs. I say generally because some units provide signal outputs of 1.5V or even 2V. The Line Out connector can be connected to a set of amplified speakers or to your home stereo for It is important that the resources allocated to the sound card do not conflict with other devices. If conflicts do occur, there are a number of ways of changing the current setup, depending on the type of card you have. sockets on their backplane bracket. These sockets are: Mic In, Line In, Line Out, Speaker Out and Midi/ Joystick. The Mic In socket accepts low level input signals from the microphone and these are typically only a few milli­ volts. The Line In is for line voltage signals and these are typically around 1V. These voltages are generally found on the line level outputs of VCRs and most audio equipment. 22  Silicon Chip even greater volume output. The Speaker Out socket (stereo) delivers an amplified Line Out signal and is connected directly to a pair of speakers. People sometimes mistakenly connect amplified speakers to this socket, which results in massive distortion due to signal overload. If you find that you get massive distortion and a lot of sound output at low volume settings, check your connections to the sound card. Amplified speakers must be connected to the Line Out socket. The Midi/Joystick connector is a dual-purpose connector that can either be used for Midi input or to accept a joystick, the latter being the most popular. Midi is used primarily by musicians and only rarely for home use, which is why this socket doubles as a joystick connector. Joysticks are great to use in some games but be warned: a cheap joystick is just that . . . cheap. If you want a joystick that really works, you will have to pay a bit more than $30. Owners of cheap joysticks will under­stand this statement. Sound card hassles Sound cards, although great to have and often a necessity, have traditionally been a common source of problems. Fortunately, most modern sound cards are exceptionally well made and with the advent of Plug and Play are now also easy to set up. It is imperative that the sound card be set up correctly, whether it be for Windows 3.x or Win95 or DOS. You need to know the sound card’s IRQ (interrupt request) number, port setting and the DMA channel. Stereo cards often require two DMA channels, while the Midi section also requires a port setting. In Windows 95, this information is usually found automatical­ly during the Plug and Play installation routine. Conversely, in Windows 3.x you have to feed in all the necessary information yourself. You glean this information when you install the card (most sound cards now come with software that tells you the current setup). It is important that the resources You can check the resources assigned to the sound card via the System Properties dialog box (Windows 95). This is brought up by double-clicking the System icon in Control Panel, clicking the Device Manager tab, selecting the device, clicking Properties and then selecting the Resources tab. the data could be transmitted, thereby allowing stereo sound to be produced. Sound card technology has since advanced even further, giving higher sampling rates and better quality sound. The 32-bit sound card is now the card of choice for sound enthusiasts and music professionals. Of course, a 32-bit card costs more than its 16bit cousin. A 16-bit card such as the Sound Blaster Vibra16, for example, costs $150-200, whereas the 32-bit Sound Blaster AWE32 costs around $500. But wait – the 64-bit sound card has now made its appearance which means that prices for 32-bit sound cards are on the way down. Sound cards & network cards allocated to the sound card do not conflict with other devices. If conflicts do occur, there are a number of ways of changing the current setup, depending on the type of card you have: (1) Pre Plug and Play cards – in the old days, hardware jumpers on the board determined the setup. To change these jumpers, you had to open the computer, remove the sound card and reposition the jumpers in accordance with the instructions in the manual. The card then had to be replaced and tested again. (2) Almost Plug and Play cards – Plug and Play may be new but there have been Plug and Play “wannabes”. These were the cards that used software to alter the settings for you. This meant that you did not need to open the case when there were problems; instead, you could quickly reconfigure the card using software. However, you still had to select the settings yourself and the software could not detect possible conflicts. This meant that settings were generally chosen on a trial and error basis. (3) Plug and Play – with Plug and Play, the cards became smarter and we moved into a new era of computing that allowed almost anyone to add hardware. Plug and Play does what we have been asking for, for a long time: it asks the card what resources it wants and checks whether they conflict with those used by other devices. If they don’t, those resources are allocated to the new device. If they do, the system automatically makes changes to avoid such conflicts. All this is done by the system BIOS during the boot-up sequence. When you want to change the settings, you can quite often do it on the fly; ie, you can change the settings without resetting the computer or restarting Windows 95. The important thing about Plug and Play is that it works without asking us any questions. Port conflicts Although IRQ conflicts are generally the cause of sound card problems, port conflicts can be a problem too. When you have a conflict, always check the port settings as well. DMA settings can also cause problems, so make sure these are correctly allo­ cated. As a general rule, you can allocate DMA channels 1 and 5 to a sound card. Early sound cards were 8-bit designs that gave reasonably good sound, although a relatively low sampling rate meant mono sound output only. The later 16-bit cards effectively doubled the rate at which Network cards and sound cards sometimes do not work well together. If you use a network card in a business environment and are experiencing troubles, try removing the sound card. Quite often that fixes the problem. If so, try changing the settings for the network card and try again. Of course, it is not necessarily the sound card that is at fault in these circumstances but it can get in the way by compet­ing with the network card for resources. If necessary, leave the sound card out altogether. After all, sound is not that important on a business computer when you’re trying to make money. If you must have both types of card, try changing the sound card. The better sound cards have more options when it comes to configuring them, which means that you should be able to avoid potential conflicts. Cheaper sound cards can also conflict with the BIOS settings of some SCSI cards. Personal preferences From a personal standpoint, I’ve always found that Crea­tive’s Sound Blaster range works extremely well. These sound cards come with excellent manuals and they are now all Plug and Play which makes them very easy to install. Best of all, the Plug and Play feature actually works, provided of course that you have a Plug and Play BIOS and are using Windows 95. Another reason for choosing the Sound Blaster range is that Creative continually upgrades the software and makes it readily available via SC the Internet. August 1997  23