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Opti-FET Compressor

MEDIA:

Owners manual are available here: Printable (323KB) | e-Manual (447KB)

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Upgrades Available Now!

The Opti-FET Compressor has undergone some changes to incorporate a new amplifier design, add selectable warmth settings, and add a selectable low-pass filter. These changes will be included in all new units going forward, and the modifications will be made available to current owners as an upgrade option. Please visit the Product Upgrade Information page for more details.

DESCRIPTION:

The FEA Opti-FET Compressor is designed with both audiophile and studio quality features that many musicians enjoy.

The new audio path has been redesigned with the FEA 3S output amplifier circuit for warm tone and excellent noise rejection that features a “class A” FET output driver and a passive optical gain reduction element. The 3S amplifier utilizes an audiophile grade Burr-Brown™ operational amplifier and Toshiba™ field effect transistors for outstanding performance. The operational and FET driver amplifiers are integrated in a unique way to take advantage of the favorable qualities of both types of amplification. This 3S amplifier has selectable modes of operation for a clean or warm tone. The warm tone mode was modeled to match the tone of the original Opti-FET circuit. The input stage is a high impedance, hi-fi amplifier buffer. The input amplifier has been designed to have minimal signal distortion and maximum headroom for all input signal levels.

Another feature in the Opti-FET Compressor is the extensive side-chain control which is not commonly found in most pedal type compressors today. Like many quality studio rack compressors, the Opti-FET compressor has all of the common controls available to the user to accurately shape his or her tone. Along with the full feature set of side-chain controls a three band equalizer is available. This EQ only affects the amplitude of frequencies of the signal in the compressor control circuits. This allows the user to modify the compression threshold points by boosting or cutting the frequency bands. The Opti-FET compressor also has a side-chain loop feature, similar to many rack compressors. This allows the user to be more creative with the use of other outboard pedals. Multi-band EQ, or buffered volume pedals are a few that can make this pedal even more versatile when used in the side-chain loop.

FEATURES:

Small footprint - 4 1/2 inches by 3 1/2 inches
THRESHOLD, RATIO, ATTACK, RELEASE and GAIN controls. The control ranges for the ATTACK and RELEASE have been optimized for use on both bass and guitar.
The compressor exhibits 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 compressor side-chain utilizes precision full-wave rectification of the audio signals in the THRESHOLD circuit to improve tracking. This also reduces the possibility of “pumping” with very low frequencies.
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 output and does not pass through any electronics.
EQUALIZER foot switch enables the three band equalizer for the side-chain control circuit. The three band EQ only affects the amplitude of frequencies of the signal in the side-chain control circuit.
LOOP SEND/RETURN jacks are for placing external processors or EQ’s in the compressor side-chain control circuit. These jacks are only active when the EQUALIZER foot switch is enabled.
Two DIP switches (internal) to switch between clean or warm tone.
DIP switch (internal) for high-frequency filter.
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 Opti-FET Compressor keeps nearly all of the circuit’s 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.

TECHNICAL SPECIFICATIONS:

ATTACK:	2ms to 150ms
RELEASE:	50ms to 1S
RATIO:	1.5:1 to 20:1
THRESHOLD:	-47dBu to infinity
Make-up GAIN:	-4 to 23dB
DIP switch selectable filter:	12KHz -6dB/oct
Side-chain EQ Freq:	LOW 30Hz, MID 250Hz, HI 2KHz
Maximum Input:	13dBu
Maximum Output:	13dBu
Residual Output Noise:	-52dBu from 10Hz-20kHz (un-weighted) with no compression and output gain set to maximum. This is the absolute worst case noise scenario.
Frequency Response:	20Hz - 20KHz +2/-3dB
Input Impedance:	1M ohm
Output Impedance:	10K ohm
Current consumption:	Approx. 30mA
Battery life:	Approx. 17 hours continuous use
Power adapter (not included):	9VDC 2.1mm negative center pin

Product Related News:

May 19, 2010 - News: Press release on Premier Guitar -- FEA Labs Introduces Opti-FET Compressor

May 19, 2010 - News: Press release on Harmony Central -- FEA Labs Presents: The Opti-FET Compressor

Notice:

Specifications and design are subject to change without notice. However, we will make every attempt to keep information on the web site current to the latest product revision.