Grp Synthesizer - A4

The A4 of Italian manufacturer GRP is the successor of the limited and "oversized" A8 /A6 synthesizers. It is strongly influenced by these and shares traits of their sound generation and their sequencer unit. The operating concept of selecting modulation sources via rotary switches and thus (almost) achieving the flexibility of a modular system has also been adopted. The A4 is reduced in size and functionality and compared to A8/A6, but absolutely equal in sound quality and workmanship. A classic dream synthesizer.

The A4 is framed in a nicely crafted wooden case. The rotary switches, potentiometers and sockets are all of very high quality. The arrangement of the components is roughly oriented to the classic oscillator, mixer, filter and VCA signal routing. Below are the classic modulation sources: Envelopes and LFOs ...and a two-row sequencer.

An overview of the most important features:

• Three oscillators with six waveforms each, exponential and linear FM, hard sync and sub oscillator (Osc 1 and 2)

• Ring modulator, Noise with White and Pink Noise. Sample and Hold

• External Input with Envelope Follower

• Audio Mixer for Oscillator 1-3, Sub Oscillator, Noise, Ringmodulator and External Input.

• Filter Section: Dual filters each with Overdrive: Multimode SVF and LPF with variable edge steepness.

• Stereo output with Auto Pan function2 envelope generators AHDSR or ADSR with loop function

• Two envelope generators AHDSR or ADSR with loop function

• Two LFOs from very slow up to 2.5Khz and with various waveforms

• Sophisticated analog sequencer that can also be found in the A8. With 2*8 or 1*16 steps total length, different playback modes, ratcheting and clock divider.

• Extensive MIDI implementation