Why Amiga modules sound different on headphones (and what Modulo does about it)
On an Amiga, two channels go hard left and two go hard right. Through speakers that sounds wide, on headphones it sounds like two songs, one per ear. Here is why, and how Modulo fixes it without touching the music.
Put on headphones, play a ProTracker MOD in almost any player, and chances are the drums sit in your left ear and the bass in your right. Nothing is broken. That is exactly how the Amiga plays it.
Four channels, two sides
The Amiga’s sound chip is called Paula. She has four channels, and they are wired straight to the outputs: channels 1 and 4 go to the left, channels 2 and 3 go to the right. There is no pan knob. A composer in ProTracker did not choose where a sound went: the channel did.
So on an Amiga every sound is either fully left or fully right. Nothing lives in the middle.
Why that was fine back then
In 1990 your Amiga was plugged into a TV or a pair of speakers on the desk. Both of your ears hear both speakers, and the room mixes the two sides together. Hard left and hard right simply sound wide.
Headphones take the room away. Your left ear only gets the left channels, your right ear only the right ones. A bassline on channel 2 and a drum loop on channel 1 turn into two separate songs, one per ear. It is fun for a minute and tiring for an album.
What Modulo does
Modulo knows where the sound is going. For Amiga modules it sets the stereo separation by the output:
- Headphones: 60 %. The two sides move towards each other, so every sound is still clearly left or right, but both ears hear the whole song.
- Speakers: 100 %. The full, original width, because the room does the mixing for you.
It switches by itself the moment you plug in or connect your headphones, and back when you take them out. You can set the width yourself too, with the Stereo width slider in Settings › Sound. At 0 % you hear mono.
Next to the width there is Output, for when you want something else entirely:
- Mono puts both sides in each ear. Handy when you listen with one earbud.
- Stereo is the normal choice.
- Surround makes the sound wider and roomier, and still sounds fine in mono.
And with Modulo Plus there is crossfeed in the EQ: it lets a little of each side leak into the other ear, the way speakers in a room do.
None of this changes the module itself. The notes, the samples and the effects stay exactly as the composer left them; Modulo only decides how the two sides reach your ears.
And Paula herself
Paula also colours the sound. Every Amiga sends her output through a low-pass filter, and not every Amiga the same way. On the A500 the filter sits low enough to round off the top: warm and a bit soft, the sound most people remember. On the A1200 it sits much higher, so the same MOD sounds brighter and crisper.
Modulo lets you pick: A500 (the default), A1200, or Off for the clean digital sound. Try the same module on all three. You will hear why people still argue about it.