A ribbon microphone is a type of dynamic microphone whose heart is a very thin and light metal, usually aluminium, ribbon. This ribbon is suspended in a strong magnetic field. When sound waves hit it, it vibrates and its movement in the magnetic field creates a weak electrical voltage that exactly matches the original sound. The sound character of these microphones is often described as 'warm', 'soft' and very natural. They capture detail excellently, especially in the higher frequencies, but unlike condenser microphones, they deliver it without harshness or aggression. It is typical for a ribbon microphone to pick up sound equally sensitively from the front and back, while strongly suppressing sound coming from the sides. Due to their soft presentation, they are popularly used for recording vocals, electric guitars from apparatus, wind and string instruments or as so-called overheads for capturing cymbals in a drum kit. Historically, ribbon microphones were very fragile, but modern designs have become much more durable. Their weak output signal requires a high-quality and powerful microphone preamplifier. There are also active ribbon microphones that have a built-in preamplifier and require phantom power to operate, which in turn could damage older, passive models.