Genesis:Preamp Fix (Model 1)
Early model 1 Japanese Mega Drives and the earliest US Genesis consoles have slightly overdriven audio from the headphone jack, slightly spoiling what is otherwise well-balanced and clean stereo audio output. Although this issue was corrected with the later VA3 motherboard revision, it can also be corrected on VA0 through VA2 model 1s by substituting several component values. This modification was originally developed by Ace on the Sega-16 Forums.[1] It is also worth noting that this is the only audio modification approved by the 16-bit Audiophile Project for recording high-quality Genesis/Mega Drive game soundtracks.
Note that performing this mod will greatly reduce the volume of the mono output from the AV out and RF.
Required Materials and Tools
- JIS/Phillips head screwdriver
- Soldering iron
- Leaded solder
- Flux
- Tweezers
- Two 10K ohm 1206 SMD resistors
- One 18K ohm 1206 SMD resistor
- Two 4700 pF 1206 SMD capacitors
Procedure
Follow the below picture for whichever motherboard you have.
VA0, VA1 and Japanese VA2
A VA1 is depicted but the points are the same for the VA0 and Japanese VA2.
US VA2
Samples
- - This sample, recorded from a VA2 Genesis, demonstrates what a stock VA0 through VA2 sounds like through the headphone output.
- - How it sounds after the preamp fix. This was recorded from a VA0 Japanese Mega Drive.