The Hanging Note Bug on the Sound Blaster 16 is a frustrating issue that disrupts MIDI playback in games like Hexen and Doom, causing notes to stick and loop endlessly. Specific to DSP chip versions 4.11, 4.12, and 4.13 [1], the bug stems from faulty firmware that mishandles certain MIDI commands, resulting in persistent audio glitches. While the Sound Blaster 16 has other issues, this particular glitch can be fixed by replacing the affected DSP chip on the soundcard, restoring clean MIDI playback and ensuring uninterrupted audio for these classic games.
What do you need
You definitely need to have the correct equipment to perform this replacement:
- Low-melt solder (recommended because there are other plastic sockets that could melt using hot air)
- PLCC44 SMD socket (if you want the new chip socketed. Make sure to get the 44-pin SMD version!)
- Soldering iron (small tip if you want to install the socket)
- ATMEL AT89C52-24JC (this is the chip to which we need to flash the patched firmware to)
- Chip Programmer (I have the T56, but this has been replaced by the T76)
- Patched Firmware (DSP_v413_maelgrum Version 5 – direct download)
ALTERNATIVELY, you can reach out and I can provide you with a programmed chip and the correct socket (15USD + shipping).
I can also provide the service of replacing the chip for you, but considering high shipping cost, it might not be feasible. Also, it would be better to combine multiple items for shipping (e.g. PCBs, hardware, or other products I am selling to reduce the shipping cost per item). Best would be to just contact me and sort things out.
Instructions (Video)
If you are interested, there is also Part 1 of the video which introduces the Hanging Note Bug and I try to fix it by using a software patch called “FixMPU“.