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Sound Blaster¶

For many who owned a gaming PC in the 1990s, the name Sound Blaster is a synonym for “sound card” — and rightly so, as the Sound Blaster family of cards by Creative Technology was the de facto standard for DOS gaming. The first Sound Blaster was released in 1989, and it quickly became the best-selling expansion card for the PC. Virtually all games from 1990 onwards had Sound Blaster support in some shape or form, and this remained unchanged for the rest of the DOS-era until the late 90s.

DOSBox Staging can emulate all major revisions of the Sound Blaster family. One of the most common models was the Sound Blaster 16 which has good (but not perfect) backward-compatibility with earlier cards. This is the sound card DOSBox Staging emulates by default to ensure the widest possible compatibility with games.

Most games that support the Sound Blaster work fine with the DOSBox Staging defaults, and don’t require you to load any DOS drivers. A small percentage of games, however — especially from the early Sound Blaster days — only work with a specific model, or require a driver to be loaded. Please refer to the List of games that require a sound driver on the wiki for further details.

For standalone Createive Music System (CMS) / Game Blaster see Creative Music System, for AdLib, OPL, AdLib Gold, and ESFM configuration, see AdLib.

On-board synthesisers¶

In addition to their digital audio playback capabilities (also referred to as PCM sound), all Sound Blaster models feature at least one on-board synthesiser for the generation of music and sound effects. The most important of these is the AdLib that is present on all Sound Blaster cards. The AdLib is also referred to as OPL sound (after the Yamaha OPL range of chips responsible for the “AdLib sound”), or FM sound (after the OPL chip’s FM sound synthesis capabilities). DOSBox Staging uses the highly accurate NukedOPL library to achieve a nearly bit-perfect emulation of the OPL chips.

The other less common synthesiser is the Creative Music System (also referred to as C/MS, or CMS) which is only present on the earliest Sound Blaster models.

The standalone AdLib, CMS/Game Blaster, AdLib Gold, and ESFM modes are covered separately in AdLib.

Default settings¶

The default Sound Blaster settings shown below have been selected for the widest possible compatibility with games. Most games can auto-detect the presence of a Sound Blaster card and these settings, but in case they need a little help, here are the values to use:

Setting Config setting Default value
Base address (or I/O address, or port) sbbase 220
IRQ (or interrupt) irq 7
DMA (or low DMA) dma 1
High DMA (or HDMA) hdma 5

If you have configured a game for Sound Blaster speech and music but can’t hear both or maybe there is no sound at all, or if the game hangs or crashes, first double check that the above settings have been set in the game’s configuration. Many games don’t let you to set all of them manually and just assume some common fixed values instead. Please refer to the detailed description of the config settings for troubleshooting tips.

Sound Blaster models¶

The below table lists all Sound Blaster models emulated by DOSBox Staging, along with their main capabilities:

Model sbtype value Digital audio Synthesiser
Game Blaster gb N/A CMS (stereo)
Sound Blaster 1.0 sb1 8-bit mono 23kHz OPL2 (mono)
CMS (stereo)
Sound Blaster 2.0 sb2 8-bit mono 23kHz OPL2 (mono)
CMS (stereo)
Sound Blaster Pro sbpro1 8-bit mono 44kHz
8-bit stereo 23kHz		 Dual OPL2 (stereo)
Sound Blaster Pro 2.0 sbpro2 8-bit mono 44kHz
8-bit stereo 23kHz		 OPL3 (stereo)
Sound Blaster 16 sb16 16-bit stereo 44kHz OPL3 (stereo)

Sound Blaster 1.0¶

The original Sound Blaster 1.0 was released by Creative Technology in 1989 as the successor of their Game Blaster card. It was the first sound card on the market to have digital audio playback capabilities; it could output 8-bit digital audio at up to 23kHz sample rates on a single mono channel. Full compatibility with the CMS and the AdLib (Yamaha OPL2) played a critical role in the card’s enormous success. In less than a year, the Sound Blaster became the best-selling expansion card for the PC.

This had transformed DOS gaming, as games could use realistic digital audio effects while simultaneously playing music via the OPL2 or CMS synthesiser chips.

Use the following setting to enable Sound Blaster 1.0 emulation:

[sblaster]
sbtype = sb1

Note

Certain games from the early Sound Blaster days might only work with the Sound Blaster 1.0 and no other models.

Sound Blaster 2.0¶

The Sound Blaster 2.0 was released by Creative Technology in October 1991. Similarly to its predecessor, the Sound Blaster 1.0, it can play back 8-bit digital audio on a single mono channel, but the maximum sample rate has been increased to 44kHz.

The card retains the perfect AdLib (OPL2) compatibility, but CMS support was only available as an optional add-on. Some early games specifically written for Sound Blaster 1.0 might have problems with this or later cards.

Use the following setting to enable Sound Blaster 2.0 emulation:

[sblaster]
sbtype = sb2

Sound Blaster Pro¶

The Sound Blaster Pro (retroactively also referred to as Sound Blaster Pro 1.0) was released by Creative Technology in May 1991. This was the first model that introduced stereo sound into the Sound Blaster lineup. It is backward-compatible with earlier models, but in addition to 8-bit mono playback of digital audio at up to to 44kHz, it’s also capable of stereo 8-bit output at a maximum of 23kHz. A distinctive feature of the card is a pair of on-board Yamaha OPL2 chips to support stereo synthesised sound.

This is the only Sound Blaster model with such a dual OPL2 configuration; many games take advantage of it and output stereo OPL music when configured for the Sound Blaster Pro.

Use the following setting to enable Sound Blaster Pro emulation:

[sblaster]
sbtype = sbpro1

Important

Games with stereo OPL sound are usually targeting either the dual OPL2 equipped Sound Blaster Pro 1.0, or the OPL3 chip of later models (OPL3 is capable of stereo sound in a single chip). It is important to configure these games for the appropriate Sound Blaster model via the sbtype setting, and select the same model in the game’s sound setup. Failing to do so will produce mono OPL sound at best, or no sound at all at worst.

Note

This is the only card supported by the known OEM releases of Microsoft Windows 3.0a with Multimedia Extensions.

Games with dual OPL2 stereo music

The following games are known to support stereo dual OPL2 music when configured for the Sound Blaster Pro (sbtype = sbpro1). Select “Sound Blaster Pro” (or just “Sound Blaster” in some cases) in the game’s sound setup to hear stereo OPL.

Sound Blaster Pro 2.0¶

The Sound Blaster Pro 2.0 was released by Creative Technology in 1991, quickly replacing its predecessor, the Sound Blaster Pro.

It is functionally the same as the earlier Sound Blaster Pro with one key difference: instead of the dual OPL2 chips, it sports a single Yamaha OPL3 chip also capable of producing stereo sound. The OPL3 has perfect backward compatibility with the single-OPL2 configuration of earlier cards, but not with dual OPL2.

Use the following setting to enable Sound Blaster Pro 2.0 emulation:

[sblaster]
sbtype = sbpro2

Important

Games with stereo OPL sound are usually targeting either the dual OPL2 equipped Sound Blaster Pro 1.0, or the OPL3 chip of later models, such as the Sound Blaster Pro 2.0 (OPL3 is capable of stereo sound in a single chip). It is important to configure these games for the appropriate Sound Blaster model via the sbtype setting, and select the same model in the game’s sound setup. Failing to do so will produce mono OPL sound at best, or no sound at all at worst.

Games with OPL3 stereo music

The following games are known to support OPL3 stereo music. Configure the game for the Sound Blaster Pro 2.0 (sbtype = sbpro2) or Sound Blaster 16 (sbtype = sb16) to hear stereo OPL3 output.

Sound Blaster 16¶

The Sound Blaster 16 was released by Creative Technology in June 1992. This is the first Sound Blaster card to support CD-quality sound (stereo 16-bit digital audio at 44kHz sample rate). The card features the Yahama OPL3 chip that has perfect backward-compatibility with OPL2 (but not dual OPL2), and supports stereo operation in a single chip.

DOSBox Staging emulates the Sound Blaster 16 by default. Most games either support this card directly, or will work with selecting an earlier Sound Blaster model in the game’s setup, making use of the card’s backward-compatibility feature. This is a good overall default, but if you’re an audio enthusiast or would just like to get the best possible experience out of a given game, reading the Selecting the best Sound Blaster model for a game section is highly recommended.

Use the following setting to enable Sound Blaster 16 emulation:

[sblaster]
sbtype = sb16
Games with true 16-bit digital audio

While most games advertised Sound Blaster 16 support, the majority only played back 8-bit samples due to floppy disk storage constraints. Starting around 1995, CD-ROM titles began incorporating genuine 16-bit recordings, typically at 22 kHz. The jump from 8-bit to 16-bit is noticeable primarily as reduced background noise; the higher sampling rate often matters more to the perceived audio quality than the bit depth alone.

The following games are known to use true 16-bit digital audio with the Sound Blaster 16 (sbtype = sb16):

  • AH-64D Longbow
  • Blood
  • Command & Conquer
  • Command & Conquer: Red Alert
  • Crusader: No Remorse
  • Crusader: No Regret
  • Descent II
  • Duke Nukem 3D
  • Dungeon Keeper
  • EcoQuest 2
  • Eradicator
  • Fade to Black
  • Freddy Pharkas
  • FX Fighter
  • Gabriel Knight
  • Gabriel Knight 2
  • Hi-Octane
  • King’s Quest VII
  • Leisure Suit Larry 6
  • M.A.X.
  • Mission Critical
  • Pepper’s Adventures in Time
  • Police Quest IV
  • Quake
  • Quest for Glory IV
  • Rise of the Triad
  • Shadow Warrior
  • Shattered Steel
  • Slater and Charlie Go Camping
  • Space Quest 6
  • Star Trek: The Next Generation
  • Torin’s Passage
  • Under a Killing Moon
  • The Pandora Directive
  • Wing Commander III
  • Wing Commander IV

Environment variables¶

Many DOS programs use the BLASTER DOS environment variable to auto-detect and auto-configure the Sound Blaster card. On a real machine, this variable is set up in AUTOEXEC.BAT during the Sound Blaster driver installation process.

DOSBox Staging injects the BLASTER environment variable at startup based on the card’s configuration in the [sblaster] section. You should never set this variable manually.

To view the value of the variable, execute the SET BLASTER DOS command. For example, this is the output you’ll get with the default settings:

BLASTER=A220 I7 D1 H5 T6

The meaning of the space-separated values are as follows:

  • Axyz — base address (sbbase)
  • Ix — IRQ (interrupt) number (irq)
  • Dx — DMA channel (dma)
  • Hx — High DMA channel (hdma)

The number after the T parameter describes the type of the card:

  • 1 – Sound Blaster 1.x
  • 2 – Sound Blaster Pro
  • 3 – Sound Blaster 2.x
  • 4 – Sound Blaster Pro 2
  • 5 – Sound Blaster Pro MCA — not used by DOSBox Staging
  • 6 – Sound Blaster 16, 32, AWE32/64, or ViBRA
  • 10 – Sound Blaster MCA — not used by DOSBox Staging

Selecting the best Sound Blaster model¶

DOSBox Staging emulates the Sound Blaster 16 by default to ensure the widest overall compatibility with DOS games. This lowest common denominator setting will serve you well if you just want to play some games with minimum hassle. If that’s the case, you might as well stop reading this chapter now, and only come back to it if you’ve encountered issues with certain titles, or if you want to further your understanding of the subtler differences between the various Sound Blaster models.

For the audio enthusiasts who are still with us, here’s the thing: if you want to coax the best sound out of a particular game, often you’ll need to select a specific Sound Blaster model the game was primarily developed for. Although the Sound Blaster 16 is compatible with earlier models, this compatibility is imperfect and is plagued by a range of issues:

Stereo bug¶

Due to a design flaw, games with support for stereo digital audio on Sound Blaster Pro output mono sound only on the Sound Blaster 16.

Different analog low-pass output filters¶

Sound Blaster cards before the Sound Blaster 16 have a fixed frequency low-pass filter on the output to reduce the effects of aliasing which sounds like metallic overtones when playing digital audio at low sample rates.

This fixed filter was changed to a variable-frequency design on the Sound Blaster 16, and the character of the filter was also altered. The old filter let a good amount of the metallic overtones through, resulting in a characteristic gritty, crunchy sound, while the new variable brick-wall filter was much more effective at reducing these overtones.

The result is that low sample rate digital audio typical to earlier DOS games sounds overly muffled on the Sound Blaster 16 compared to earlier models.

Dual OPL2 support¶

The Sound Blaster Pro 1.0 is capable of stereo “dual OPL2” operation thanks to its two on-board OPL2 chips. This is the only Sound Blaster model with a dual OPL2 configuration. Previous models feature a single OPL2 chip that can output mono sound only, and later cards have the improved OPL3 chip that can also output stereo. Stereo sound on dual OPL2 and OPL3 needs to be programmed differently, and some games were targeting only one of these two incompatible stereo OPL modes. Therefore, games that were written for dual OPL2 will only produce stereo synthesised sound on the Sound Blaster Pro 1.0 and no other model.

To provide a good out-of-the-box experience that works well enough with most games without tinkering, DOSBox Staging defaults to the imaginary modern filter setting on all Sound Blaster models. This implements simple linear-interpolation instead of accurately emulating the analog output filter — this makes most games sound decent regardless of the Sound Blaster model in use, but it’s not authentic.

For the best authentic results, set the most appropriate Sound Blaster model for each game via the sb_type configuration setting. Additionally, set the sb_filter setting to auto to let DOSBox Staging select the output filter appropriate for the emulated Sound Blaster model.

For example, use the following settings to enable authentic Sound Blaster Pro 1.0 emulation with dual OPL2 support:

[sblaster]
sbtype = sbpro1
sb_filter = auto

Determining the best Sound Blaster model for a game can be tricky as the different cards were released very close to each other; simply looking at the game’s release date often doesn’t help much. Ultimately, you’ll need to do a little bit of research, experiment, and trust your ears.

Audio artifact mitigation¶

Real Sound Blaster hardware exhibited certain audio quirks, such as startup pops, that were simply part of the experience at the time. DOSBox Staging faithfully emulates these behaviours, but also provides settings to mitigate them when strict authenticity is less important than a clean listening experience. These settings are best applied on a per-game basis.

When a Sound Blaster card powers on, there is a brief transient pop before the DMA audio stabilises. The sbwarmup setting silences the initial DMA output for a configurable number of milliseconds (100 by default) to suppress these startup pops. Reduce it if initial audio is getting cut off.

For OPL hanging-note and DC-bias mitigation, see AdLib.

Mixer channels¶

The digital audio of the Sound Blaster is output to the SB mixer channel, while the AdLib (OPL) synthesiser has its own dedicated OPL channel. Both channels can be either mono or stereo, depending on the particular Sound Blaster model being emulated.

The Creative Music System (CMS) synthesiser has its own dedicated CMS channel, which is always stereo.

The upshot of this is that the digital audio and synthesiser volumes can be adjusted independently via the DOSBox Staging mixer (e.g., in games that use digital audio for speech and sound effects, and the synthesiser for music).

Note

Starting with the Sound Blaster Pro, programs can adjust the volume of the digital audio, OPL, and CD Audio channels via the Sound Blaster software mixer. By default, DOSBox Staging forwards these adjustments to the DOSBox mixer, allowing programs to change the volumes of these channels. This can potentially result in your manually set volumes being overridden. To prevent this from happening, set the sbmixer configuration setting to off.

Configuration settings¶

The Sound Blaster settings are configured in the [sblaster] section. The Creative Music System and AdLib and page covers the related OPL and CMS settings that also live in this section.

sbtype¶

Sound Blaster model to emulate.

Possible values:

Please refer to the Sound Blaster models section for an overview of the capabilities of the different models.

sbbase¶

The base address (also referred to as I/O address, or port) of the Game Blaster / Sound Blaster.

Possible values: 220 default, 240, 260, 280, 2a0, 2c0, 2e0, 300.

You can typically only choose between 220, 240 and 260 on real cards.

The AdLib Music Synthesizer Card has a fixed base address of 380 that cannot be changed. Games can access the Yamaha OPL chip on Sound Blaster cards either at base address 380 (this is the AdLib compatibility mode), or at the Sound Blaster’s base address.

Important

Virtually all games with Game Blaster / Creative Music System (CMS) support only work with the base address set to 220. A significant number of early 90s games with Sound Blaster support also assume a base address of 220 and do not let the user the change it, making this the most compatible setting.

irq¶

The IRQ (interrupt) number of the Game Blaster / Sound Blaster.

Possible values: 3, 5, 7 default, 9, 10, 11, 12.

You can typically only choose between 3, 5, 7 and 10 on real cards,

Many games do not recognize IRQs higher than 7.

Important

Cards before the Sound Blaster 16 defaulted to IRQ 7. From the Sound Blaster 16 onwards, the default had been changed to IRQ 5. Because of this, many earlier games assume IRQ 7 and do not let the user to change it. Games that assume IRQ 5 are rarer, making 7 the overall most compatible setting.

dma¶

The DMA (also referred to as low DMA) channel used for 8-bit digital audio on the Sound Blaster.

Possible values: 0, 1 default, 3, 5, 6, 7.

You can typically only choose between 0, 1 and 3 on real cards.

Important

Many earlier games assume DMA 1 and do not let the user to change it, making it the most compatible setting.

hdma¶

The high DMA channel used for 16-bit digital audio on the Sound Blaster 16.

Possible values: 0, 1, 3, 5 default, 6, 7.

You can typically only choose between 5, 6 and 7 on real cards.

sbmixer¶

Allow the Sound Blaster mixer to modify the DOSBox mixer.

Possible values: on default, off

Starting with the Sound Blaster Pro, programs can adjust the volume of the digital audio, OPL, and CD Audio channels via the Sound Blaster software mixer. By default, DOSBox forwards these adjustments to the DOSBox mixer which can potentially result in your manually set volumes being overridden. To prevent this from happening, set the sbmixer configuration setting to off to retain full manual control over the channel volumes. Note that this might break some games that use the mixer to achieve certain effects (e.g., dynamically lowering the music volume when voice-overs are playing).

sbwarmup¶

Silence initial digital audio after card power-on for this many milliseconds.

Default value: 100

This mitigates pops heard when starting many Sound Blaster based games. Reduce this if you notice initial playback is missing digital audio.

sb_filter¶

Filter settings for the Sound Blaster digital audio output:

  • auto – Use the appropriate filter determined by the sbtype setting.
  • sb1, sb2, sbpro1, sbpro2, sb16 – Use the digital audio filter of this Sound Blaster model.
  • modern default – Use linear interpolation upsampling regardless of the sbtype setting. This is the legacy DOSBox behaviour; it acts as a sort of a low-pass filter. Use auto instead to enable model-authentic filter emulation.
  • off – Don’t filter the digital audio output.
  • <custom> – Custom filter definition; see Custom filter settings for details.

These are the model specific low-pass filter settings for the digital audio output:

sbtype Filter type Cutoff frequency
sb1 2nd order (12dB/oct) 3.8kHz
sb2 2nd order (12dB/oct) 4.8kHz
sbpro1
sbpro2		 2nd order (12dB/oct) 3.2kHz
sb16 brickwall variable;
half of the playback rate
sb_filter_always_on¶

Force the Sound Blaster Pro 2 filter to be always on. Other Sound Blaster models don’t allow toggling the filter in software.

Possible values: on, off default