Bluetone Extreme 15 is based on Trainwreck Express with some our own mods. It is said to be world`s most ultimate lead tube guitar amp. The key idea is to control amp sound only with guitar volume pot from shimmering cleans to roaring and singing lead sounds. This amp configuration is a single channel amp with 1,5 x 12AX7 preamp stages, 12AX7 PI and 2x6V6GT power amp. You can only use these tubes in this amp. There is no need to bias power tubes, because power amp is cathode biased model. Output is some 14-15 W. This amp contains also our innovative 3-step, variac style OPC (Output Power Control), which reduces output power even to 4-5 W without ruining sound quality. Compared to original circuit, we have added some our own innovations to improve amp usefulness. There is a Low Cut switch, which helps when playing with heavy distortion. Fast-Gradual switch increases/decreases preamp distortion, Heat control adds warmth to preamp, Cut control impacts to high frequencies in power amp. With PPIMV Master Volume and OPC power control you have endless possibilities to dial desired sounds with any suond pressure level without spoiling sound quality. This amp also contains an adjustable, unbalanced Line Out with internal Dummy Load for silent recording. This big sounding full tube guitar head weighs only 4,9 kg.
More info here: https://www.bluetone.fi/extreme-15-head/