BtBx (V. 1.1, Pure Profit; $3.99) is a very flexible app with a step-sequencer interface that gives a sampled electronic drum kit, synth basses, trumpet, percussion, and keyboard. Each sound can be reversed on any sequence step and can have its volume, cut-off frequency, and resonance adjusted. There are also simple distortion and delay effects available for each sound. You can store up to 16 patterns.

FEATURES, AT A GLANCE

Eight drum sounds
Two instrument sounds
Two real-time synthesizers
16 step drum machine-style sequencer
16 patterns
Keyboard with +/-3-octave range
Real-time mutes
Tempo adjustment of 40 to 240 bpm
Lowpass filter with cut-off frequency and filter
Distortion effect
Delay effect synched to tempo

Find out more information about BtBx.