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V1.1 March 2019
Audio Settings
All Sega Genesis/Mega Drive consoles include
two internal sources of sound. The first is the six
channel, Yamaha YM2612 OPN2 Four Operator
Frequency Modulation Sound Generator. Later
Genesis/Mega Drive consoles integrate a slightly
different sounding YM3438 OPN2C. The second
is an integrated recreation of the four channel
Texas Instruments SN76489 Programmable Sound
Generator. Mega Sg also includes a DAC to allow
analog audio output via its headphone jack.
Headphone Output – Sets the volume level from
the headphone jack.
High Impedance Phones – If you are using studio-
grade headphones, select this option and Mega
Sg will try to provide the power necessary to drive
those phones. If you are using earbuds or typically
low impedance computer/gaming headsets,
leave this option unchecked. If your headphone’s
impedance is above 50 Ohms, then select this
option. If below 30 Ohms, leave it unchecked.
Between 30 and 50 Ohms, see which setting works
best for you. You will notice an increase in the
loudness of the audio with this item checked.
Channel Levels – Allows you to set the relative
volume levels of the FM and PSG sound sources.
The FM is inherently stereo, panning its output left
and right, so these outputs are affected. The PSG is
dual mono, so each channel is given its own volume
level. The default level should match a Genesis/
Mega Drive Model 1 with a discrete YM2612.
Channel Panning – Allows you to pan channels left
and right relative to center. The original YM2612
has stereo output, so these panning sliders can
influence the inherent separation. The original chip
does have a certain amount of audio bleed.
The original PSG does not have stereo capabilities,
so this is an added feature. Set the sliders to 0 to
make the sound source mono.
-3db Output Cut – Some monitor embedded
speakers and soundbars clip or cannot recognize
a full-volume signal. This option reduces the
volume to reduce the peaks below their maximum
amount (0db). Try enabling this option if you are
not hearing any sound or hearing clipping sound
from Mega Sg.
Enable Cartridge & CD Audio – This option must be
turned on to hear audio from the Sega CD via Mega
Sg. Use this option to enable expansion audio from
a device like the Power Base Mini FM or the Mega
EverDrive v2/X7. Otherwise you should disable
this option if you are not using one of the above
because the audio inputs can pick up bus noise.
Swap Left & Right – This option reverses stereo.
Cartridge Audio Volume – Sets the volume of the
expansion audio.
Lowpass Filter – This allows you to apply a lowpass
filter to the audio output. You may wish to use this
to attenuate the higher frequency components of
FM audio. The slider allows you to specify a cutoff
frequency from 100-20000Hz in 100Hz steps.
If you go too low the sound will start to sound
muffled. The low pass filter is a 256-order low pass,
so the cutoff frequency will sharply attenuate audio
above the set frequency. The filter will not affect
PSG audio or audio from any external source.
Ladder Effect Depth – This effect is sometimes
called DAC Noise, because the YM2612 sends its six
FM channels to its internal DAC sequentially, there
can be unnecessary noise or crossover distortion
produced when the audio is output. Some games
had their audio designed with this in mind and
sound less punchy when played in a system with
a YM3438, which almost totally eliminates the
effect. After Burner II is the classic example, set
the level to 4 or 5 to get a more analog sound when
playing that game.
