I have this amp and I know the fan is not normally needed . But when turned on it gives off an annoying whine. I just purchased another TFB550 for our church, from Atlanta Bass Gallery. BTW, Jim was great to work with! This amps fan makes the same sound. I believe it may be because it's a pretty cheap fan. I was thinking of upgrading it but wasn't sure what size these are. It looks like what may be used on a computer processor. Any ideas? But I love the amp! I was glad when my church put me in charge of buying the equipment for starting a second Praise Band! Wasn't hard to decide to go with another TF!