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Basic Voice Mod Creation Guide

A Tutorial for Super Smash Bros. Ultimate

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This tutorial will be a simple temporary guide on how to make basic voice mods for the time being until SaltyNX opens the gates for more complicated voice and music mods, or until TNN releases his guide.

Some Notes Before Starting

This tutorial assumes you have an exploitable Switch and are capable of modding the game.

Please do not release unfinished work as a full mod. If you require help with this guide and audio modding, the recommended option is to ask in the Smash Ultimate Modding Hub Discord (link is on the front page of the Ultimate section here), but making a help thread also works.

Credit any content you may have used for your mods when releasing or showcasing. Taking credit for content you did not create from scratch isn't cool or permitted.

Also, if you had to decimate quality just to get to something workable, It is highly advised you set it aside for public release until SaltyNX comes out.


Setting Everything Up

The most crucial thing you need is access to a tool that can export wavs, mp3s, or oggs such as audacity. This guide will specifically go over how to use Audacity to inject wavs into smash. If you don't know how to work audacity, there are many easy guides to use it in powerful ways. For the most part youll just need to adjust volume however.

Importing Your Audio And Compression

Make sure you have the requirements labeled, and have nus3audio and the conversion pack downloaded. In Audacity or another Audio program, import the audio file with CTRL-SHIFT-I if you use Audacity from wherever you might get it from (E.G sounds-resource, youtube, etc) and trim it down to what you want it to be. Export as WAV/MP3/OGG and then drag the said Audio file over "convert to IDSP."

Injecting Into a nus3audio File

Now, you want to inject into a nus3audio of your choice. Fighter sound effects are in root > sound > bank > fighter, while Fighter voices are in root > sound > bank > fighter_voice. Find the nus3audio, and put it in the same directory as the nus3audio.exe file that we had earlier.

Now, click on the directory at the top of your screen to enter CMD in the directory of the nus3audio program. Type in 

nus3audio.exe yourfileofchoice.nus3audio.exe -e FolderNameOfChoice 

This will extract all of the idsp banks (sound effects) into a new folder. You can then compare the file sizes of your new IDSP (or IDSPS) from earlier. Any bigger than the original sound effect must be compressed further, and a good way in Audacity to compress a wav is to lower the Hz.

Usually going farther below than the setting in this picture will cause it to sound a little worse than expected, so do your best to trim it down to what you need. Only reduce bitrate below 24000 if you absolutely have no choice but to decimate the quality.

 Just try to keep a balance, and make sure the sum of your new IDSP files file sizes is under that of the sum of the originals sum.

Once you're ready to inject, open up nus3audio again with a different command:

nus3audio.exe yourfileofchoice.nus3audio -v 

Then it should flash a big listing of all of the audio files. On the side there is an Index number. Find the file you wish to replace with a new file and see its Index number (I.e index number 370 in se_common is the sound effect that plays when you die on the last stock.)

Now, you want to press E to enter the Edit mode. It will ask for an index number, so type that in. After that, press D (which stands for Directory) and it will ask for the files directory. Copy paste the directory and add the file name at the end (E.G I:\Hefty\Downloads\tools\nus3audio\vc_ganon_attack08.idsp)

Press Q to go back to the first options menu, and repeat the process as many times as needed to inject all of the new IDSP files you have that are required. Then press W and select the name for the new file, E.G ReplacementNus3audio.nus3audio. Now you are ready to compress if needed and test ingame.


You should now have your nus3audio file(s) that are ready for compressing with Smashpad. The instructions are in the description of the download page for smashpad at the top of this guide. Some files will not need to be compressed: see troubleshooting to see what I mean.


Game Softlock or Crash

Sometimes audio files have no compression at all, meaning you can skip compressing it! You can tell they have no compression if the uncompressed file size and the compressed file size (as seen in the following picture) are the same.

If your modded files before compressing are over the decompressed file size of the vanilla files, your mod will crash when put in-game as well, as stated earlier. If you are unable to reduce contents and resources (which in the vast majority cases are solvable for ordinary voice mods,) you must wait for SaltyNX.


Well, that about wraps up this guide. If you have any questions, please do not DM me and instead leave a comment with detail to some degree so I can help you better with your issue. If possible, I can also communicate over Discord.
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  • access_time 6mo
    When I run the command to extract all the idsps, it gives me this: "Assertion failed: !memcmp(nus3Header, "NUS3", 4), file source/nus3audio.c, line 153"
    Any idea what that's about?
    what's poppinggggguh
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  • Prawnsacrifice avatar
    Prawnsacrifice Joined 9mo ago
    279 points Ranked 51694th
    access_time 8mo
    i too am very interested in converting music for battles
    URL to post:
  • Sharkbyte avatar
    Sharkbyte Joined 8mo ago
    access_time 8mo
    Okay so, I was trying to follow this tutorial but instead of doing it for a voice mod I ended up trying to do it for music. I wanted to replace the menu theme and I ended up getting everything right with the correct file, offset, and good file size. However, I messed up somewhere in between with the conversion maybe? Do you have any advice on what to do different for music replacing?
    URL to post:


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Key Authors
made guide
fork of streamtool that has a bunch of useful conversion batch files
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jam1garner Joined 4y ago
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author of nus3audio
VGAudio team
making the tools needed for conversion of audio to idsp and etc
parts of this were re-written by him


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