Okay, so you know how sound is made when something vibrates really fast? Like when you shake a bell and it makes a ringing noise. Well, inside some really fancy and old-fashioned music equipment, there are things called valves (also known as tubes). They kind of look like little light bulbs and they help electricity flow through the equipment.
But the special thing about valves is that they can change the sound of the music. When the electricity flows through them, it makes the vibrations that create the sound happen in a relaxed and smooth way. This makes the music sound warm and kind of like you're listening to it in a cozy room with soft lighting.
It's kind of like how when you're upset, your mom or dad might give you a hug and make you feel better. The valves give the music a big hug and make it sound nicer.
People who love music really like the sound of valves because it makes things sound like they're from a long time ago and it feels very special.