Monophonic analog synthesizer

The Behringer Pro-1 is a clone of the popular retro classic Sequential Circuits Pro-One which was once conceived to be a monophonic Prophet-5. Those who know and love recordings of Depeche Mode and Yazoo, will enjoy recognizing a lot of those sounds with the Pro-1.

The synthesizer

The two assertive oscillators, each based on a CEM3340 chip, have sawtooth and square waveforms, an octave switch, fine tuning and pulse width control. Oscillator A can be synchronized to oscillator B, the second tone generator is additionally equipped with the triangle waveform and can be switched to low mode as well as decoupled from the pitch control. Both VCOs are brought together in the mixer, where the noise generator is also located, which can be replaced by an external signal. The beautiful basic sound is processed with a characterful 24dB lowpass filter, also known as Curtis VCF. It behaves similar to a Moog filter, but due to the IC CEM3320 it sounds different than the transistor cascade. The two crisp ADSR envelopes are assigned to the filter and VCA. An LFO with three waveforms is connected to the targets via the modulation bus. The special features of this instrument include the waveforms that can be activated simultaneously in both oscillators and in the LFO.

Modulations Bus

The modulations are assigned on the left side of the control panel. The filter envelope, oscillator B and the LFO, each with their own attenuator, are available in parallel as sources. These are assigned to the targets frequency oscillator A+B, pulse width oscillator A+B and cutoff directly or via the modulation wheel (or midi controller). Wild oscillator drifts, sync sounds, sirens, FM for filter and/or oscillator A as well as pulse width modulation are possible if used with care. If you turn everything up at once, it gets really wild! The modulation bus is the hottest feature of the Pro-1 next to the sound.

Sequencer & Arpeggiator

The ingeniously simple sequencer provides access to two patterns, each of which can be up to 40 steps long; pauses can also be programmed. The notes are played via a connected MIDI keyboard. After the input, the patterns can be transposed with the keyboard. The Arpeggiator primarily offers the playback modes Up and Up&Down, but can also be integrated into the pattern. Synchronization to other equipment is done via the analog clock input or MIDI/USB.

Inputs (for modular use)

Inputs

• Mod MW CV (replaces the modulation wheel in the modulation bus)
  
• OSC CV (CV input pitch control)
  
• Gate/CLK (clock input for sequencer & arpeggiator)
  
• LFO CV (CV input for LFO speed)
  
• EXT (audio input)
  
• Cutoff CV (CV input for cutoff)
  
• Resonance CV (CV input for resonance)
  

Outputs

• LFO shape (CV output of the LFO)
  
•  KB CV (CV output pitch)
  
• Gate (gate output)
  
• Mixer (audio output of the mixer)
  
• Filter Env (CV output filter envelope)
  
•   Amp Env (CV output VCA envelope)
  
• Phones (headphone output)
  
• AAudio Out (instrument output)
  

MIDI, USB and Main Out 6.3 mm jack are also available on the back.

The Behringer Pro-1:

• Clone of the Sequential Circuit Pro-One (1981-1984)
  
• Desktop synthesizer
  
• Analog
• Two oscillators with CEM3340 ICs
  
• Noise generator
  
• Mixer
• 24dB Curtis-Filter (low pass)
  
• Two ADSR envelopes
  
• LFO with three waveforms
  
• Modulation bus
  
• Audio input
  
• Arpeggiator
• Sequencer
  
• CV/Gate inputs/outputs
  
• USB & MIDI