I am using a cassette recorder that copies to a mini SD card. This is what it looks like on Audacity. Sounds o.k. but why is it just 2 colors and below the zero?
That’s likely a hardware error called DC Offset.
Audio is always supposed to average out to zero (middle) no matter how loud or what the sound is.
Yours doesn’t. If you absolutely have to use this tape player and interface, you can force it to work with a couple of tools.
Drag-select and cut off the tall blue sections at the beginning and end.
Select everything remaining by clicking just right of the UP arrow to the left of the track.
Effect > Normalize > [X] Remove DC (and don’t select anything else) > OK.
You will have to do that to each tape or capture unless you repair the player or get a new one.
The blue colors in the wave are wrong or confused because sound doesn’t normally do what yours does.
Koz