I recently picked up one of those carvin b800 heads but i have it hooked up to a 4x10 & 1x15 and it cuts out on me and powers off when im playing and its not even up high. master on 2 bass middle treble not even at 11 0'clock just using a passive p bass. it then comes back on after bout 5 mins. is this normal or is there something im doing very wrong here? Any help would be greatly appreciated.