Sound Blaster Z Survival Guide

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Introduction

Sound Blaster is the legendary brand of aftermarket audio devices for PC by Creative Labs. It is famously known for providing Dolby Digital Live (DDL) and Digital Theater Systems (DTS) encoders for S/PDIF output. Thus enabling digital surround sound using a single optical cable on you Windows PC. However, setting up your Sound Blaster on Windows can sometimes be frustrating. This guide will address common issues people are facing notably with Sound Blaster Z PCIe card. Some of that may be relevant for other similar Sound Blaster products too.

Encoder issues

Sound Blaster digital Encoder takes the 5.1 surround output of your Sound Blaster Z Speakers device, encodes it using DDL or DTS and pushes the resulting bitstream through its S/PDIF optical output. Trouble is, this feature, as provided by Creative Labs, comes with a few issues of its own. Not to worry though, here are workarounds you may want to deploy.

PC won't go to sleep

When the digital encoder is enable it prevents your PC to go to sleep.
Quick fix, execute the following command as administrator to prevent Sound Blaster Z to keep your PC awake:
powercfg -requestsoverride DRIVER "Sound Blaster Z" SYSTEM
You can run powercfg -requests to see all devices or software currently keeping your PC awake.
Run powercfg -requestsoverride to see which of those devices you have overridden.

Crackling sounds & channel swap

For some users the encoder stops working properly after listening to audio continuously for a few minutes. What you often get then is crackling sounds and the front channels audio coming out from the surround speakers. It turns out it is a known issue that Creative Labs never managed to fix properly it seems.
I just needed to edit the following registry key to fix it:
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\cthda\HDB\11020027\HW_CTL_MX_BSIZE
In my case it was set to 0x00000008 and I simply set it to 0x00000010 instead. Though if that does not fix it for you you may have to experiment with larger buffer size. Apparently this is a PCIe only issue so if you are using a Sound Blaster USB device this is certainly no concern to you. There is a long thread on TechPowerUp about this issue.

Actually the above workaround does not quite work with the latest driver and Sound Blaster Command. Instead you need to download the somewhat older Sound Blaster Z Control Panel, the installation file is named SBZ_CD_L13_1_01_11.exe. In fact when using the latest drivers instead the registry key keeps reverting back to its default value which break your digital encoder again.

Volume control

When using digital encoder changing the Speakers volume on Windows has no effect. That's most inconvenient as all system volume control keys on your keyboard are thus rendered useless. Instead to adjust the volume when the encoder is running you need to change the levels on your Sound Blaster What U Hear recording device. Fortunately Nico Jeske developed an open source utility to sync a Recording device levels with a Playback device volume which is just what we need. Go download and install MasterVolumeSync from GitHub.

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Empty audio stream

The digital encoder keeps sending an empty audio stream when no sounds are being played. Some people like it as it fulfils the function of an audio guard by preventing your receiver and speakers to go offline. I, on the other hand, would like my Sonos Playbar to go offline when no audio is played. In fact when my Sonos Playbar is online and does not play any sound it does produce a noticeable white noise which is not present once offline. I have not found a proper solution for that yet. I just have a workaround that involves muting that What U Hear Recording device which is also best done through MasterVolumeSync as mentioned above. Once muted my Playbar goes offline after about a minute. Ideally we would need a solution that would automatically mute and unmute that What U Hear device when audio stops and starts. Maybe we could use some code from SPDIF Keep-Alive to implement such a solution and contribute it to MasterVolumeSync.

Bonus

Attached to this article is the official Sound Blaster Z icon you can use to display on your Sound Blaster Playback and Recording devices.

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Addendum

After running with HW_CTL_MX_BSIZE set to 0x0000000C for while I ran into that issue again during a long audio session, couple of hours maybe. Since I increased the buffer size to 0x00000010.
Even with 0x00000010 the issue can still happen. Now trying 0x00000012.
To fix the issue you need to restart the Sound Blaster Audio Service from Windows Services.

References

 

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