PC soundcard page

    General introduction to PC soundcards

    Nearly every PC nowadays comes with a sound card.They vary immensely in sound quality, features and input/output options.Sound cards fall into two distinct groups - consumer and professional.The card that comes with the computer would slip into the consumer group,which means usually the cheapest card that the computer manufacturer canfind the laters buzzwords like "3D audio", and is put there to make noisesfor computer games. Professional (or prosumer - an in between category) cards often havemultiple higher quality inputs and outputs, a much higher price and areusually bought later as an add-on.Pro cards usually have LINE inputs only, leaving the Mic pre-ampoption open for users to choose.Professional audio equipment runs at a nominal level of +4dB, consumerat -10dB. Sound cards that are designed to link to other pro equipmentwill run at +4dB, and have greater headroom.Practically all normal PC soundcards have a built-in computercontrollable mixer functionality which is used to adjust howloudly different sound sources sound out and also controls whatis being recorded by the soundcard. IN Win95,98,NT etc then there isa little speaker icon in the bottom right hand corner of the screenand double-clicking it will start you the mixer application whichallows adjusting those soundcard settings. In other operating systemsthis adjustment is usually a separate piece of software which youneed to run to do those things. If you do not have any ideawhat would be good settings for those differen sliders, it is a goodidea to set about 1/2 to 2/3s up for each fader, and then adjustfrom those settings to direction which works best for you.

    Interfacing to soundcards

    PC soundcards have typically many different kinds of interfaces. This also applies the sound functions built into some motherboards. The most commonly used interfaces on normal PC sound cards are analogue audio output, analogue audio input and microphone input. Those are typically all implemented with 3.5 mm stereo jacks. The "normal" color coding of those connectors are the following:

    • Blue is normally line in.
    • Light green is standardized to be the stereo line-out (works for amplified amplified speakers, works for headphones on many cards as well)
    • Pink is the microphone input.
    The connections on some PCs or soundcards can be somewhat different and there can be more than those connections in them. For example some 5.1 channel PC sound cards use normal light green for left+right main speakers, black for rear speakers and orange for front+LFE. The PC or soundcard you have should have come with an Owner's manual as well as a large hook-up sheet that explains what all the connections are.

    Many on-board computer sound systems now have software-configurable ports, allowing the same sockets to act as surround outputs, Mic or Line inputs, Headphone or Line outputs. Look at the control panel for your sound system. It may be in the System Tray, it may be in Control Panel. See what options you are offered. Some new computer audio interfaces actually auto-sense the kind of device that each jack is connected to, and try try to adjust their circuitry and connections to match what they auto-sense.

    In addition to analogue interfaces some soundcards can have digital interfaces. For example Sound Blaster Live cards often use yellow connector for Digital output (S/PDIF for digital recievers/surround sound).

      Audio output connectors

      Line level outputs on consumer PC soundcards can typically output signals up to 2V levels and ouput impedance typically from tens of ohms to few hundred ohms (quite typical is 30-400 ohms). Those line level outputs are designed to be connected to consumer equipments (normal Hifi amplifier with -10dB nominal level line input) or powered multimedia speakers. Just get the suitable cable in between the computer and the Hifi system and you have your sound on on main speakers. The normal line level output of this kind can normally nicely drive up to around 5-10 meters of cable without any noticable effect to sound quality.

      The typical 3.5 mm output jack used usually for all soundcard connectiond has the following pinout on signal output:

      3.5 mm stereo jack

      In some soundcards the line output is provided using pair of RCA jacks which are typically used for interconnecting consumer audio devices. In any case all you need is a suitable cable (cable with RCA conneector on one end one which fits to your soundcard) to hook your PC to your HIFI system line level input (for example CD, AUX or TAPE audio input). You can use the following input jacks: AUX audio, CD audio, CD-V audio, in order to connect the Line Output of the sound card to the Line input on the AUXfunction. Those inputs you should primarily try to use for PC soundcard. If you do not have those you can try tape inputs. Note that phono inoutis meant only for connecting a record player to in and is not suitablefor computer soundcard hookup.

      If you happen to for some reason get some annoying humming (this happens in some case bit not always) then take a look at Ground loop pages to get information how to solve this problem if you get it.

      Some soundcards have headphone outputs instead of line output. The specification of headphone output could be for example 100 mW to 8 ohms. This kind of headphone output can be used to drive hadphones directly. You can used headphone output like a line output to connect you soundcard to you HIFI system. If you don't have a line out, a headphone out will drive a line in of HIFI system very nicely. Just turn its volume down some to get the level into the right range. Quality will usually not be quite as good as a line out would be, but it will be at least good enough to serve for the crappy sound chip that's in your laptop (Practically every laptop has a crappy built-in soundcard). The usual offense is poor SNR due to large amounts of background noise picked up from the hard drive, various buses, etc.)

      Speaker level outputs on some soundcards (not in many newr ones) have typically around 2W of output power and can drive 8 ohm sepakers or 32 ohm headphones nicely. If you have non-powered speakers or headphones, this is the output to use for them.

      Most modern PC soundcards nowadays have line outputs that have fairly low output impedance. This makes them compatible with a variety of loads including normal stereo line inputs and stereo headphones. Low impedance on the soundcard otput also helps to carry the sound for many meters without problems.

      Audio input connectors

      Typical line level audio input connections are generally designed to accept audio signals in the range of 500 mV to 2V. They are designed to operate nicely with consumer equipments like tape decs and CD players nicely (those devices use typically -10dB signal level). You can easily connect the tape outputconnectors form your HIFI amplifier into your souncard inputs and so getyou HIFI system connected to souncard input (now you can use amplifiersource selectors and record to any signal source in amplifier or connectedto it). Line level audio input connectors are high impedance inputs (typically around 10-47 kohm). The pinout is the same as in the line level output:

      3.5 mm stereo jack

      The real performance and voltage rages of line inputs vary from card to card.Most cheap consumer sound cards run off a 5 volt internal supply soany buffering opamp stages they have will clip someplace around 1.5-2volts. Some better cards can easily produce unclipped 2 volts rms. Somecards designed for professional use can handle input levels up to 10V.

      Line inputs on PC soundcards have very simple capabilities: they can accept line level analogue stereo sound. You take care of interfacing instruments and other type of sound sources by using a mixer or preamp. When using the audio input connected take a note that there is a difference between which inputs are made available to the soundcard's output, and which one is made available for recording. To be able to recordthe sound from the input you must select that input for recording use before you can record anything from it.


      Generally all PC soundcards have microphone input. Soundcard mic inputs are generally pretty crappy, meaning usually that they are noisy and frequency response leaves much to be desired. Soundcard microphone inputs are usually optimized only for telephone type voice applications, not for any serious music recording. The microphone input in soundcard is generally designed to be used only with a "computer microphone" in mind. This category means those cheap computer microphones you get sometimes with the computer and can buy from the computer shop. This it to what use they are designed for. And if you get this kind of microphone it will work practically with any normal soundcard. If you connect some other microphone type, then your resuls vary from card model to another (some can take other microphone types better than some other). Sound Blaster soundcards (SB16,AWE32,SB32,AWE64,Live) from Creative Labs use 3.5 mm stereo jack for the electret microphones. The microphone connector uses he following wiring pinout:

      3.5 mm soundcard microphone input connector

      The 5V voltage on the connector is heavily current limited (typically goes through around 2.2 kohm on soundcard). Depending on the card the voltage might not be exactly 5V (usually something between 3 and 5V when no microphone is connected). Practically all other soundcard makers have copied this pinout and connection idea to their soundcards. The circuit idea used in the soundcards microphone inputs is the following:

      Sound Blaster mic input circuit

      There has also been standardizing work going on this connector also. For example PC99 standard mentions the PC soundcard microphone interface details: Three-conductor 1/8 inch (3.5 mm) tip/ring/sleeve microphone jack where the mic signal is on the tip, bias is on the ring, and the sleeve is grounded. This design is optimized for electret microphones with three-conductor plugs, but will also support dynamic microphones with two-conductor (ring and sleeve shorted together) plugs. Minimum AC input impedance between tip and ground: minimum, 4 kOhm; recommended 10 kOhm. Input voltages of 10.100 mV deliver full-scale digital input, using software-programmable .20 dB gain for low output microphones.Bias should be less than 5.5V when no input and at least 2V with 0.8mA load. Minimum bias impedance between bias voltage source and ring: 2 kOhm. AC-coupled tip to implement analog (external to ADC) 3 dB rolloffs at 60 Hz and 15 kHz.

      Most sound card inputs require a minimum signal level of at least 10 millivolts. Sound Blasters and some older 8-bit cards need 100 millivolts. Practically all consumer soundcard supply bias voltage on their outputs to power the electret microphones (the only microphone type which works with this kind of cards). The input impedance of the typical PC soundcard microphone input is typically in order of 1500 to 20000 ohms (can vary from card to card).

      This discrepancy means that if a typical professional microphone is connected to a sound card input, the user will have to shout into the microphone or hold it just an inch or so away (or both) in order to produce a strong enough signal for the sound card to "hear." Other problem with dynamic professional microphones is that dynamic microphones do not like DC current, but soundcards have 1-5V power supply for feeding Electret mics on the 3.5mm-jack?s ring, which can touch the tip of the connector when you plug your microphone in and if you are unlycky it can damage your microphone.

      There are two possible solutions for the low volume problem with professional microphones connected to soundcard. First option is to try to increase the sensitivity of the sound card input with the control software which come with the soundcard (audio mixer application or such). This might more or less help depending on soundcard used. If the input sensitivity cannot be increased eough, another option is to amplify the microphone signal before it goes into the sound card input. This can be done by running the microphone signal through a device called a mic preamplifier or mic-to-line amplifier and feed that signal to the line level input in the soundcard (this approach usually gives better sound quality also).

      Note for serious audio recorders: Soundcards with mic inputs on minijacks are usually low-quality devices, which means that they are not suitable for high quality recording odf audio (they are still OK for general multimedia use or internet telephony). Such sound cards are not designed for high quality recording. Get a real soundcard and use a real audio application if you want quality results. If you want to get really good quality microphone recording using computer the microphone wiring should be balanced and the microphone preamplifier should be external to the computer casing. Usually you get quite acceptable results by using an external microphone preamplifier that is connected to line input in the soundcard. Genrally for a home recorder, I can recommend a small decent quality mixing board connected to soundcard line input. With such mixer between microphone and soundcard, you will get good results and have freedom to select practically any microphone you want (anything you can connect to that mixer).

      Using the soundcard sound inputs

      Generally the most troublesome task for people trying to record using soundcard is getting the soundcard settings right so that they can start recording from the correct source with their favourite sound application like Goldwave or the basic Soundrecorder with Windows.

      Many people seem to have problem that they hear the sound they want (line input or mic) but can't seem to record the sound. The reason for this problem lies in the way the soundcards are built.

      A normal PC soundcard has two sets of mixer settings: one selects what you hear on sound output (headphones/speakers) and other set selects the recording sound source (you shoud select here the input from which to record).

      To get the recording settings right in Windows system you just need to go into the Windows Volume Control (double-click on the speaker icon in your system tray) and make a few adjustments: First go to Options, Properties, be sure you are looking at Playback, and check all the checkboxes so you see all controls. Exit the Properties dialog. You will probably find a few more sliders there than you did before. The Line In slider controls the amount of Line In that gets fed to your speaker. This is independent of what goes to your recorder app. Now go back to Properties, select Record controls, and once again check all the checkboxes. Exit the Properties dialog; you are now looking at Record controls. Now you get a list of available input sources and their adjustments. This list is list is slightly different depending on your sound card. If you want to record from line, be sure the Line In is selected -- or not muted, depending on your sound card. The Line In level here controls the amount of Line In that gets to your recording. (And to avoid unnecessary noise, turn down to zero, or mute, or deselect all the other Record controls.) Same basic idea applies also to the microphone input and other recording sources.

      Other way to do this same thing in Windows is double click on the volume control on task bar to bring up all the controls. The microphone and line is shows up in the Playback settings. Click on the options menu then properties. Select "record" and check that microphone and line in setting there.

      How to use enable the microphone input for recording in Windows do the following: Open the volume applet, go to 'options,' then 'properties,' and select 'recording'where it says 'adjust volume for.' It's also a good idea to check all theboxes under 'show the following volume controls.' OK out of there, muteeverything but the mic, kick its volume up, and try again. Quite many popular soundcards (but not all) offer "what you hear" option on the recording controls. When you select at as the sound recording source, you will be always recording the same thing you hear at the soundcard speakers. This could be helpful if you are frustrated in always adjusting the recording controls.

      TIP: You can start the Windows sound card mixercontrol program with recording settings visible (no need to go through menus to get to them) with the following command line: sndvol32 /r

      If you use some other operating system you need to determine yourself where to find the recording controls and how to use them.

      Digital interfaces

      Today many new sound cards, especially the PCI ones, are equipped with a digital input connector for connection of the digital signal from the CD-ROM drive. In addition to this many modern PC soundcards have aoptions to have digital input and output connectors. The implementations of PC soundcard digital outputs vary. Some card have optical, come have coaxial outputs.Also coaxial outpus vary somewhat. Some are designed with output meeting full S/PDIF standard. Some are implemented in such way that they output TTL levle signal when not loaded and around S/PDIF levels when connected to 75 ohm load (typically implemented with 5V TTL output connected to output connector through around 680 ohms resistors).

    Soundcard software

      Converters, players and utilities

      • Awave - audio and wavetable instrument file format converter, editor and player    Rate this link
      • Ptmid - Converts MIDI files to MOD/MTM, with C source    Rate this link
      • Sound2Midi - Sound2Midi intercepts audio signals received from the microphone and determines Pitch, Dynamics and Timing, sending each note as MIDI data straight to your Sequencer. The process is achieved real-time so by the end of your recording you're ready to replay your transcribed performance using any available MIDI instrument sound. Even creating drum sequences is made possible through the Rhythm mode, enabling you to construct all the instrumental parts of an orchestral score. This is a commercial for Windows, with free demo version for download.    Rate this link
      • Sound Cue System - sound effect playback system for live theatre productions, shareware    Rate this link
      • SoX - sound file format converter for Unix and DOS    Rate this link
      • StripWav - convert newer WAVE files containing extra header information to the canonical format that many older programs require    Rate this link
      • WaveDrop - very simple to use utility for playing looped waveform files    Rate this link
      • Sound Recorder Software - List dozens of software records audio streaming from any source into mp3, wav, wma, ogg, and other audio files    Rate this link

      Sample editors

      • Goldwave - very good shareware sample editor program    Rate this link
      • n-Track - shareware multitrack recording software for Windows 95    Rate this link
      • Wave Repair: a WAV File Editor - shareware editor designed for ultra-fine level alteration of the waveform shape in WAV files, identifying and repairing the clicks, pops and ticks    Rate this link
      • Audacity - Audacity is a free audio editor. You can record sounds, play sounds, import and export WAV, AIFF, Ogg Vorbis, and MP3 files, and more. Use it to edit your sounds using Cut, Copy and Paste (with unlimited Undo), mix tracks together, or apply effects to your recordings. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. Built-in effects include Echo, Change Tempo, and Noise Removal, and it also supports VST and LADSPA plug-in effects. Audacity is being developed by a team of volunteers under the open-source model. It is written in C and C++. All of the source code to the program is made available under the GNU General Public License. The software runs on Windows, Mac OS 9/X and Linux / UNIX systems.    Rate this link

      Signal generator software

      With suitable software and soundcard you can use your PC as a signal generator that gan generate different waveform signals.

      Signal waveform analyzing tools

      With suitable software a PC with a soundcard can be used as a multi-purpose audio frequency signal analyser. You can for example use PC as audio signal oscilloscope, VU meter, spectrum analyzer, frequency response analyzer.

      • audioTester - spectrumanalyzer, wavegenerator and oscilloscope with a soundcard, shareware software    Rate this link
      • FreeVIEW sound - This software turns a PC or notebook into a long-time data logger, a chart recorder, a storage oscilloscope, spectrum analyser and much more. This software works with Microsoft? Windows? 95/98/ME.    Rate this link
      • Oscilloscope for Windows - Oscilloscope for Windows is a Windows application that converts your PC into a powerful dual-trace oscilloscope. Oscilloscope uses your PC's sound card as an Analog-to-Digital Converter (ADC) to digitize any input waveform (speech, music, electric signal, etc.) and then presents it on the monitor in real time, allowing the user to control the display in the same way as on a conventional "standalone" scope, for example change gain, timebase or plot Lissajous patterns. Any soundcard can be used and data can be exported to Windows clipboard if needed. Software supports up to 20 kHz bandwidth, triggering and spectrum analyzer.    Rate this link
      • SB Analyzer - SB Analyzer is a waveform analyzing program. This version can show oscillogram, amplitude-frequency characteristic of the quadripole, spectrogram, distortion. This program is written for Windows operating system. The program with the limited opportunities is distributed freely. More features are available after you register the software.    Rate this link
      • VUmeter.exe - With this tool you can analyze things like level, stereo perspective, distortion, phase trouble and frequency content    Rate this link
      • WaveTools - A suite of real-time audio analysis tools for high quality measurements: Spectrum analyser and oscilloscope (with calibration in dB or Volts), Signal Generator (tones plus pink and white noise) and Audio Meter / Vectorscope.    Rate this link
      • WaveTools - WaveTools is a library consisting of 8 programs for manipulating mono WAV Files. Those programs can be used as a toolbox for generating and preprocessing small test samples. This program set is for Unix/Linux systems.    Rate this link

      FFT spectrum analyzer programs

      • AtSpec - low cost shareware spectrum analyzer for Win95 and NT, many functions    Rate this link
      • Daqarta - Data AcQuisition And Real-Time Analysis system, shareware version available, FFT, waaveform analyzer    Rate this link
      • Fast Fourier Transform - calculates the frequency components of a signal, reads audio from file and outputs to file    Rate this link
      • HpW Works FFT Spectrum Analyzer - FFT Spectrum Analyser with Wave Generator for Windows, commercial program, demo version available also    Rate this link
      • MicFFT V1.2 - PC Fourier Spectrum Analyzer, DOS program which supports Soundblaster, PAS16 and some other cards. MicFFT is a program that samples data from a sound card or addressable analog-to-digital (ADC) port, and plots out the spectral features of the sampled waveform. The program utilizes a Fast Fourier Transform (FFT) algorithm to transform the sampled data (in the time domain) to the frequency domain. The program gets 256 Pulse Code Modulated (PCM-see below) samples from the ADC at a defined sampling rate, and then plots the transformed data. MicFFT continuously loops between sampling and plotting. Thus, the program acts somewhat like a realtime spectrum analyzer, and on fast machines with fast sound cards, is capable of impressive performance. MicFFT can be likened to spectrum analyzers found on some audio equalizers, and can provide detailed information on the spectral components and relative intensities of continuous waveforms.    Rate this link
      • Spectrum analyzers programs for ham radio use    Rate this link
      • Sonogram - Draws colour or greyscale spectrograms from WAV files. This program is for Windows Windows 95/98/NT.    Rate this link
      • Spectrogram 5.0 Real-time spectrum analyzer - Windows freeware utility for displaying spectrograms of digital audio files, works also real-time    Rate this link
      • Spectra Plus - sound spectrum analyzer program and signal generator for Windows, free 30 day trial version available    Rate this link
      • Visual Audio - 16 band left/right channel spectrum analyzer, peak analyzer (oscilloscope), compact disc player, mixer, requires Sound Blaster, Pro Audio Spectrum or compatible sound board, and a VGA system capable of 1024 x 768 x 256 colors    Rate this link

    Multimedia speakers

    Cheap "multimedia speaker" gear is generally crap. There are some good multimeria dpaklers around, but most (especially the cheap ones) are generally poor in quality and the technical specification on their boxes are usually meaningless. (For example you can too often see 200W power on small speaker powered with 5W transformer! Definately not true.). A lot of companies have claimed to offer high-performance speakers for PC multimedia applications, and it simmes just only some of them have even put serious engineering effort into their products. The technology of a typical PC multimedia speaker is the following: The sound input comes to the speaker as line level signal that is amplified with a small amplifier and fed to the speaker elements. The speaker typically has volume control (and some have also tone controls). A typical cheap PC speaker has only one speaker element be multimidia speaker box. Because the performance of one spaker element is pretty limited, usually the lowest and highest frequencies from sound are missing. Some higher quality speakers use separate high frequency elements for better highs and separate subwoofer for better low frequency sounds.If you have bothering hiss and crackling noises coming from the multimedia speakers, the reason for this could be caused poor speaker amplifier or problems on the PC sound card side. One test to verify is what is happening is the following: First disconnect the spakers from your computer (disconnect the audio wire from speaker end if possible). If there's considerable noise at "no signal" condition, the noise is coming from the amplifier inside the multimedia speaker (meaning poor quality speaker). If the speakers do not hiss much when not plugged to computer, but the hiss increases when plugged into the computer, the noise mightbe coming from the soundcard. To reduce the noise from soundcard you can try the following tip:Mute the line in, mic and cd in when they're not in use (also any other analoge input). Usually every sound input that is not muted contributes more or less to the sound output noise.

    Audio Modem/Riser card information

    Audio Modem Riser (AMR) is an Intel specification created with the aim to "make integration of audio/modem functions on to the motherboard easier by separating the analog I/O functions to a riser card for the desktop platform.Audio/Modem Riser (AMR) and Mobile Daughter Card (MDC) new modular specifications make integration of audio/modem functions on to the motherboard easier by separating the analog I/O functions to a riser card for the desktop platform, or a daughter card for mobile. The new AMR specification defines a hardware scaleable OEM (Original Equipment Manufacturer) motherboard riser board and interface, which supports both audio and modem.

    Soundcard programming

    Modern operating systems (Windows, Linux etc.) provide a quite useful API for programming soundcards. Nowadays you don't need to do low level programming to access soundcards (like you needed to do years ago with DOS system).The normal way of outputting audio is to open a device and writing blocks of data to this device. How this exactly works depends on the OS. The audio data is generally written to output buffer. The output buffer is a block of memory which has several constrictions (on a PC, do not no about other hardware) the data in this buffer is usually transfered to the soundcard using the DMA controller. The DMA controller is a device which can copy data between memory and hardware devices without needing the CPU.Reading the audio from the sound card work in pretty much same way, only in the opposite direction.Please note that in many operating systems audio devices are opened exclusively. If another program tries to open the device when it is already open, an error is returned. Sound input works generally in the same way as the output (just in opposite direction).

      Windows soundcard programming

      In Windows, a program should refrain from directly reading and writing hardware ports on a sound card. Whenever possible, a program should instead call functions in the Windows operating system, which will do the actual hardware reading and writing for you (in conjunction with the sound card's Windows device driver). For writing data to the card, you pass that data to an operating system function that sends that data to the card's device driver, which in turn writes that data to the card. In this way, you'll create a Windows program that will operate under many version versions of Windows and work with a wide range of sound cards and MIDI interfaces. It's the driver that has the hardware specific code in it, not your program. There a "standard" that all Windows sound/MIDI drivers are written to follow. This is called Windows "Media Control Interface" (ie, MCI). The Windows MIDI Mapper, the MCI Sequencer Device (driver), and the MCI Wave Audio Device (driver) are 3 parts of MCI that are particularly relevant to sound/MIDI cards. Nowadays there is also an another alternative sound API available. It is called DirectSound. DirectSound is part of APIs provided by Directx system.


      • "Sonic" - a Digital Audio Programming Language - Sonic is a computer programming language to facilitate the synthesis and processing of digital audio recordings, with emphasis on concise coding and rapid development. Sonic contains constructs which will be familiar to users of languages like C++ and Pascal, such as assignment statements, procedures, local variables, while loops, and if statements. Sonic is specialized for working with digital audio.    Rate this link

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