Addendum to this post: https://www.reddit.com/r/Famicom/comments/1pmbf4q/twin_famicom_an500_audio_comparison_stock_vs/

Why did I do this? I found that several online guides for Twin Famicom audio fixes suggest removing the C205 low-pass filter to eliminate muffling and changing R201 from 8.2k to 2.2k for louder audio. This setup works. But it sounded terrible in my case, especially for games with loud music, adding too much gain, and some high-frequency noise isn't filtered out, which results in crackling and saturation.

This video demonstrates various audio comparisons of the Twin Famicom involving changes to the values of the low-pass filter and resistor. There are 10 setups in this video (1 for OG Famicom, 9 for Twin Famicom with tweaked LPF and resistor values for each new setup).

For my final setup, a 10nF 100V film capacitor and a 5.1K resistor are the sweet spot for C205 and R201 in improving audio clarity without encountering excessive gain or crackling.

[EDIT (12/20/25): If you want to keep the stock C205 22nF low-pass filter cap, 3.3K at R201 also works fine with no audible crackle. Volume level is about on par with an NES front-loader.]

I chose the title screen music of City Connection, as this is where these audio artifacts are most noticeable. I also included a recording on the original Famicom model (HVC-CPU-07) for comparison.

NOTE: Setup 1 is an un-modded original Famicom unit connected via RF to a Japanese VCR to composite for reducing interference. Twin Famicom is connected via composite. Both units have been recapped.

Video capture setup is via my CRT's composite output port, connected to a GV-USB2, and recorded via OBS.

I did this for experimentation purposes only. I will not be held liable if you follow this and end up breaking your Twin Famicom or burning down your house.

REFERENCES:
https://nerdlypleasures.blogspot.com/2018/01/famicom-nes-simple-tweaks-to-restore.html
http://vaot.mydns.jp/fc/tfaudio.htm
https://www.famicomworld.com/forum/index.php?topic=14505.0
https://www.famicomworld.com/forum/index.php?topic=15306.0
https://forums.nesdev.org/viewtopic.php?t=17487
https://etim.net.au/nesrgb/installation-famicomtwin/
https://www.sega-16forums.com/forum/general-discussion/tech-aid/20802-repair-log-sharp-twin-famicom/page3

3 points WFlash01

I just recently picked up a Twin Famicom myself! I still need to find an AC adapter for it though, I thought it would use the same AC adapter as the Famicom, but I was wrong, but when I finally get it up and running I'll see how bad the audio is on it

This guide will come in handy

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1 points Silver-Thanks3938

How are you powering your Twin Famicom? I'm in AUS but have a Twin Famicom but no way to power it! any recommendations?

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1 points itmustbeyzzy

I use this: https://www.digikey.com/en/products/detail/triad-magnetics/WSU075-1500-13/6600150

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