Bugbrand Phase 12 All-Pass Filter

A six-pole analogue phase shifter built around 12 all-pass filter stages and three 2164 quad-VCA chips. Designed for studio and performance use, it offers balanced TRS audio connections, CV control and hands-on control of phasing, feedback and modulation.

The all-pass stages shift the phase of the signal at their filtering frequency while preserving amplitude. Mixing the dry and processed signals creates the characteristic peaks and notches of phasing. The main Phase control sets the filter centre frequency across the full audio spectrum, with internal or external modulation available for animated sweeps and more complex movement.

The main input accommodates typical line-level signals, with up to 20dB variable gain and soft clipping for added overdrive. A separate feedback input is normalised from the phase output; inserting a jack breaks this connection, allowing the feedback path to be processed externally. Buffered outputs provide both mixed dry/wet and pure wet phase signals.

Feedback can be increased to emphasise the filtering up to the edge of resonance. The Add/Subtract switch inverts the phase output and feedback input, providing two distinct response modes. An internal jumper selects whether feedback returns to the first or second filter stage; it is set to the second stage as standard.

An internal sine-wave LFO provides traditional sweep modulation at approximately 0.08–10Hz, while the external modulation input accepts CV sources such as sequencers. The LFO is also available via a dedicated ±5V banana output. At low LFO rates, the oscillator may take some time to reach full strength after powering on.

Features

• Six-pole analogue phaser with 12 all-pass filter stages
• Built around three 2164 quad-VCA chips
• Balanced TRS input and output connections
• Variable input gain up to 20dB with soft clipping
• Normalised feedback path with external feedback insert capability
• Dry/wet mix output plus buffered wet-only phase output
• Add/Subtract phase and feedback response switch
• Internal feedback-stage jumper selection
• Internal sine-wave LFO, approximately 0.08–10Hz
• External CV modulation input with polarity/mute switch
• ±5V LFO banana output

Technical Specifications

• Audio inputs: Mono balanced 1/4" TRS jack, 20kΩ impedance
• Audio outputs: Mono impedance-balanced 1/4" TRS jack, 100Ω impedance
• CV connections: 4mm banana
• CV input impedance: 100kΩ
• LFO output impedance: 470Ω

Enclosure & Power

The standalone unit is housed in a custom aluminium enclosure measuring 4.5 × 5.25 × 3.5 inches, with PCB-material front and side panels. An internal DC/DC converter converts a 12V DC external supply to bipolar ±15V internal power.

• Power requirement: 12V DC, minimum 300mA, 2.1mm centre-positive
• Module format: 3FW
• Current draw: +50mA / -40mA

Includes original box and power supply.

Product Specs

• Item Number: 43911
• Make: Bugbrand
• Model: Phase
• Condition: Excellent
• Finish: Red
• Categories: keyboards-and-synths ⇒ desktop-synths
• Made In: United Kingdom
• MPN: 43911