Expansion Port Sound Module (EPSM)


Out of stock

You must register to use the waitlist feature. Please login or create an account


Coming soon. Please register your interest above so we can plan how many to make.

Expansion Port Sound Module (EPSM)

The Expansion Port Sound Module, EPSM for short. Is a new device made for the NES Expansion Port that has never really been used.
This device started with the idea to make something useful for the never used port.
The basic idea is to add a lot more audio capabilities to the NES without to add expensive hardware to each and every cart,
while also adding support to listen to the already existing carts with expansion audio.
Using game carts with expansion audio on an unmodified NES will only output the audio into the void, the EPSM solves this.
It’s cheaper to get a slightly pricier expansion adapter than adding audio hardware to multiple games.
The EPSM would have been possible to make as early as 1985 though in a bulkier version since the slimmed down version of the chip did not come as early.


  • Genuine Yamaha YMF288 FM Synth Chip
  • Adds 15 new sound channels to the NES for future homebrew support
    • 3 Square wave channels, also capable of noise
    • 6 FM Synth channels with Hard Panning Stereo support
    • 6 Rythm channels featuring 6 different ADPCM Drum Recordings with Hard Panning Stereo support
  • Forwards expansion audio from supported gamecarts
    • Original Famicom expansion audio games with compatible adapter
    • PowerPak
    • EverDrive N8
  • 2 different Addressing modes
    • Direct/Mapper assisted
    • Fallback mode
  • 3.5mm Jack for Stereo Output

Source and Support

Please note that although this is an open source noncommercial project Muramasa Entertainment has received permission to manufacture the EPSM from Perkka the creator of the EPSM. Please note that support is limited and before purchasing please check the Github page to see more information on the product. Also please feel free to ask questions on the NESDEV Discord on the #chiptuning or #hardware channels.


There are no reviews yet.

Only logged in customers who have purchased this product may leave a review.