The Ashdown BTA 400 Head! When Ashdown made a tube amp head, it was always going to be something very special. The BTA 400 (Big Tube Amp) partners a feature-laden ABM EVO III preamp with a sledgehammer 400W power section comprising of 8 KT88 tubes and massive output transformers. You get a sub-harmonic generator, built-in compressor and classic Ashdown 'rotary plus slider' EQ providing 20dB of cut and boost at 60Hz, 660Hz and 5kHz, supplemented by 15dB cut and boost at 180Hz, 340Hz, 1.3kHz and 2.6kHz. Comprehensive connectivity includes a balanced DI output with pre or post EQ switching, a sub-bass output, a tuner output, an FX loop and a line input, and a 4-way footswitch is included for maximum performance control. Alongside great tone and flexibility, what makes the BTA 400 really special is its reliability. With a chassis suspended on car engine mountings and a circuit design that will even survive running with no speakers connected, this is a tube bass amp head you can depend on.