ABOUT THE DESIGN:
FEA Labs is pleased to announce the new design of the feature-rich Dual Band Optical Compressor-Limiter. This new design includes a limiter switch which provides infinity to one compression so the pedal can be used as a limiter when you need it and the crossover frequency range has been broadened to include lower frequencies so that the limiter can keep a cap on the lowest frequencies. The upper compression range has been increased to 7:1 to allow you to dial in more “squash” as needed. The threshold range has been lowered to accommodate lower output instruments and the taper of the control has been changed to provide a more even range. All frequencies above 5KHz are routed around the compression circuits and mixed back into the signal at the output amplifier to preserve signal purity.
- Small footprint – 4 1/2 inches by 3 1/2 inches
- Dual optical compressors for separate Low frequency (LO) and High frequency (HI) dynamics control.
- Adjustable frequency crossover point with the range tailored for bass guitar.
- The frequencies above 5KHz are routed around the compressor circuits and are mixed back into the output amplifiers at unity gain to preserve clarity.
- THRESHOLD, RATIO, ATTACK, RELEASE and GAIN controls for the HI and LO compressors. The control ranges for the ATTACK and RELEASE have been independently optimized for the LO and HI bands.
- Both bands exhibit soft-knee compression at lower RATIO settings and hard-knee at maximum RATIO settings. The COMP LED indicates when the THRESHOLD has been reached. This LED does not indicate the RELEASE response.
- The LIMITER switch changes the LO band compressor into a LO band limiter. The LO RATIO control is bypassed and hard limiting is applied and set by the THRESHOLD level control.
- The compressor side-chains use precision full-wave rectification of the audio signals in the THRESHOLD circuits to improve tracking. This also reduces the possibility of “pumping” with very low frequencies.
- HI BYPASS foot switch. This allows the compressor to only control the Low frequencies (if desired) and to pass the High frequencies to the outputs unaffected. There is a red LED to indicate the HF BYPASS is on.
NOTE: With HI BYPASS active the HI GAIN control is inactive.
- ACTIVATE foot switch places the compressor unit in the signal chain or in Direct Bypass mode. In Direct Bypass mode the signal at the input is directly connected to the outputs.
- The compressors have minimal components in the signal paths to maintain the utmost signal quality. The signal compression is accomplished with only resistive components (Light Dependent Resistors). All resistors in the circuit are low noise 1% metal film type. The crossovers state variable filter capacitors are tight tolerance, quiet, multi-layer and metalized polyester film type. The amplifiers used in the signal path are JFET input, low-noise, low-distortion “hi-fi quality” devices.
- The power supplies onboard voltage charge pump allows the circuitry to operate at 18volts (+9 and –9 volt rails) from a single 9-volt battery or DC power adapter of 9 volts. This allows the signal plenty of headroom from active electronic guitars and aggressive playing techniques (i.e. pop and slap).
- The “switch on” power supply current is less than 1µA (micro amp) on the signal ground at the INPUT jack. This is approximately 45,000 times (-93dB) less than the commonly used method of connecting the battery’s negative terminal to ground via the sleeve of the plug inserted into the INPUT jack. The “switch on” sensing method used in the FEA Dual-Band Compressor keeps nearly all of the circuits generated white noise and transient currents out of the INPUT stage signal ground. Extreme measures have been taken to keep the power and signal paths as clean as possible.
- The power and grounds for the signal path circuitry are separated from the side-chain power and grounds to protect the audio signal from spurious noise. The power for the signal amplifiers is exceptionally clean, filtered twice for each rail and all filter stages are oversized.
- HI and LO/FULL output jacks are configured so the outputs of the individual compressors may be routed to different amplifiers or effects. The HI output is useful if you wish to use effects made strictly for guitar and route a clean LO signal to another amplifier or mixer. If only the LO/FULL output jack is used, both the HI and LO signals are mixed together for a composite full range output signal.