SNES:FXPak Pro (SD2SNES)

The FXPak Pro (formerly known as the SD2SNES) is a Super Nintendo / Super Famicom cartridge that plays games from an SD card, referred to as a romcart. It's compatible with pretty much the entire SNES library, supports instant load times and includes support for "MSU-1 audio" via its Cyclone V FPGA.



Compatibility
The FXPak Pro is the most compatible of all the SNES ROM carts currently on the market. In fact, it's actually easier to list the incompatible games, which is exactly what Ikari has done on his website: https://sd2snes.de/blog/compatibility

Firmware Download
The latest official Firmware can always be found here: https://sd2snes.de/blog/downloads

MSU-1 Audio
The FXPak Pro supports something called "MSU-1 Audio", which stands for " Media Streaming Unit revision 1". It's a homemade "enhancement chip" created by Near that allows for CD-quality audio on a SNES.

A good way to think of it is like this: Remember the SegaCD? The graphics were pretty much the same as the Genesis, but the music played directly off the CD allowing for the music to be extremely high quality. Also, the extra storage space of a CD allowed for FMV playback, within the restraints of the Genesis' processing power. Well, this is essentially the exact same thing, but for the SNES and only for patched roms.

While no physical MSU-1 chip was ever created, the code was integrated into a few emulators, as well as the FXPak Pro, allowing full CD-quality audio through real SNES hardware!

You can get lots of MSU-1 patches for SNES roms at http://www.romhacking.net/. You can also check the Zeldix forums.

Audio Mod for OLD revisions (No FXPak's or SD2SNES "Pro's" have ever required this)
All revisions of the SD2SNES starting with "H" and later (and every version of the FXPak Pro) already have a great-sounding audio circuit. If you have Rev.H or newer, you can skip this section. If your version is older, there's actually a modification you can perform to improve the output. Please scroll down for more info.

There are a few differences in the audio circuit of the SD2SNES revisions:

SD2SNES PCB Revisions A-F have slightly lower audio output. SD2SNES PCB Revision G was a quick fix for this, boosting MSU-1 audio to the correct levels but introducing some noise. SD2SNES PCB Revision H (and newer) adds an audio opamp forever fixing MSU-1 audio functionality.

This mod replaces the passive filter between the DAC and the SNES' analog mixer with with the better circuit from the Rev. H (and newer) that includes a unity gain opamp in order to fix the impedance mismatch that caused muffled and quiet audio in older revisions. Basically, it's more of a "fix" then an "upgrade", meant to eliminate the need for boosted audio files (clipping), firmware audio boost in the menu (clipping), and the Rev. G 5V mod (distortion). This finally standardizes the correct MSU-1 audio levels between real hardware and emulators.

Borti4938 has actually created a PCB that allows for a slightly easier way to add the mod. You can order the boards and components from these links (with alternative links for the components):


 * PCB: https://oshpark.com/shared\_projects/1ej3Nrdj
 * Audio amp: x1 per board: DigiKey, Mouser
 * 0.1uF 16V 0603 capacitor, x1 per board: DigiKey, Mouser
 * 10 ohm 0603 resistors, x2 per board: DigiKey, Mouser

Installation instructions: GitHub

Also, Qwertymodo has a guide on his website that shows how to directly add the components on the PCB, without a PCB. While qwerttymodo himself actually recommends using Borti's solution, here's his page for reference.



Cheap Clones
The SD2SNES is an open-source project and can be made by anyone. That being said, there are a few low-quality clones out there with problems that range from gitchy use, to no MSU audio, to it not working at all. It's strongly recommended to only purchase an FXPak Pro from a reputable reseller, such as Stone Age Gamer.

One funny thing about the clones I've seen - Even though they were made in China, they still say "manufactured by KRIKzz" and "assembled in Ukraine".

Custom Menus
You can now customize the menu of the SD2SNES/FXPak Pro using the SD2SNES IMG tool. Here's some examples:

Scrambled Screen Issue
Early models of the FXPak Pro may present an issue where your screen becomes scrambled as if sync is lost. This is not an issue with the FXPak Pro, but rather an issue with your SNES having a weak clock signal and being susceptible to interference from the FXPak Pro's MSU-1 pins. This issue can occur with regular cartridges, but it is more likely with the FXPak Pro.

Symptoms
Symptoms include the master clock slowly increasing or decreasing and your screen scrambling as shown below.

https://www.youtube.com/watch?v=9i70w7sOgXg

Covering the left-most pin on the front and back of the cartridge with tape will physically disable MSU-1 and should temporarily fix the issue and confirms that you need to apply a fix to your SNES.

Solution
Apply a Dual Frequency Oscillator (DFO) mod to your SNES or a de-jitter mod. Either one will strengthen the sync signal of your SNES to normal levels. Later FXPak Pro revisions add a 100ohm resistor to pin 1 of the cartridge followed by a 5.6uH inductor in series which further combats this issue.