Expansion audio on the Famicom is a wonderfully confusing mess
As Tim mentioned, the internal audio from the AV Famicom (and GPM motherboard Famicoms) at the cartridge slot's audio mixing pin is lower volume than the internal audio from the older Famicom models. The result of this is that the expansion audio mix sounds terrible on the AV Famicom.
But, to complicate matters, the Everdrive N8's expansion audio is lower volume than geniune carts and the Famicom Disk System. The Everdrive's expansion audio actually sounds pretty well balanced on the AV Famicom, but sounds too quiet on original Famicoms. I suspect the Everdrive N8's expansion audio level may have been set with the AV Famicom in mind because Krikkz's demonstration videos always showed an AV Famicom.
Basically, what this means for the NESRGB expansion audio mod on a Famicom is that you would need two different resistor values and a selector switch - a lower resistance for the Everdrive, and a higher resistance for genuine expansion audio carts and the Famicom Disk.
I'll buy a 100k potentiometer from Radio Shack tomorrow and I'll try to figure out the ideal resistance values for both my Everdrive and my Akumajou Densetsu cart. I'll use
this video of Level 1's music on a Twin Famicom as my reference for the proper mix volume.
It would be a whole lot easier if Krikkz could just increase the Everdrive's expansion audio volume via software to match genuine carts. Then there would be no need for wiring up a switch for different resistances.
