Stainless steel strings are usually fairly bright sounding. You still get a nice low end punch, but you get the added top end bite too. Stainless steel bass strings can be really good for more contemporary music, like modern rock, punk, pop and metal as you get that natural slight mid scoop.
You can get pure nickel wound bass strings too – these tend to be much warmer sounding, without too much low or top end, resulting in a mellower tone. What you’ll probably see more of is nickel plated steel strings. As you might imagine, these strike a really nice balance of warmth and brightness. If you’re going from Motown to pop punk all on one bass, then these strings will help you cover lots of ground.
String materials at a glance:
Nickel - Pure nickel strings have a warm sound, without too much treble bite or low-end. Perfect for the vintage tones of ‘50s/’60s pop, soul and rock.
Stainless steel - Tonally speaking the opposite of nickel strings, stainless steel is clear and bright, with clarity throughout the frequency range – great for modern sounds.
Nickel-plated steel - No surprises, nickel-plated steel offers a compromise between pure nickel or stainless steel. An all-round option for the bassist who plays a bit of everything.