Quartet Condensed Operating Instructions - Front Panel

(Click on front panel for larger photo)


DI INPUT: Selects between Instrument (10M at the front 1/4" jack, 1M at the rear jack) and Line (100K with a -20dB pad at both inputs).

MIC/DI: Selects between the MIC input (via the XLR input connector) or DI input signals (via the front or rear 1/4" input jacks).

+48V: 48 volts to the XLR input for mics requiring phantom power.

0/-20: Inserts a 20 dB pad in front of the mic input transformer.

+/-: Mic phase reversal switch. Normal phase is XLR pin 2 hot.

LO CUT: An 12dB/octave low frequency mic rolloff at 75 or 150 Hz. Center position is off.

GAIN: +33 to +63dB for the mic input, +20dB to + 50dB for the DI instrument input, and 0 to +30dB for the DI line input, in 3dB steps.

OUTPUT: Controls the output level of the preamp stage. By increasing the Gain and lowering the Output level, the harmonic content of the preamp can be varied.


HI: ±10dB shelving at 7, 10, or 15 kHz.

MID: ±10dB peaking at 0.7, 1.6, 2.2, 3.3, 5.0 and 6.5 kHz.

LO: ±10dB shelving at 50, 100, or 200 Hz.

EQ before/after Opto: Places the equalizer before or after the opto-compressor and de-esser.


THRESHOLD: Up to 27dB of compression is possible.

RATIO: The compression ratio is continuously variable 1.5:1 to 15:1.

OUTPUT: The tube line stage will supply up to +15dB of gain make-up after compression.

MODE: There are four modes of compression: Fast (peak-averaged), Average (rms detection), Vintage (program dependent attack and release times), or manual (attack 1-100ms, release 0.1-2s).


THRESHOLD: Controls triggering of the sibilance detector circuit.

FREQUENCY: Sets the detector to trigger selectively at one of 11 frequencies, from 3.4 to 11.5 kHz.

DEPTH: Sets the depth of the notch filter from -2 to -10 dB.


COMPRESSOR/OUTPUT: In the Compressor position, the VU meter indicates the amount of gain reduction. In the Output position, the VU meter indicates the signal level at the XLR and 1/4" main output connectors . The meter is electronically isolated from the signal path, and is calibrated to 0VU = +4dBu (1.23Vrms).

IN/BYPASS Switches

All are 'hard' bypass switches that remove the EQ, Compressor or De-Esser from the signal path.

Quartet Condensed Operating Instructions - Rear Panel

(Click on rear panel for larger photo)


MIC: A Female XLR input for connecting microphones using standard balanced XLR mic cables. Pin 1 = ground. Pin 2 = + (positive phase), pin 3 = - (negative phase). Note: this input may be +48v phantom powered, as selected by the '+48' switches on the front panel. Do not use phantom power on a microphone that does not require it! (e.g. dynamic, ribbon, or tube microphones). Make all mic connections before applying phantom power!

DI: An unbalanced 1/4" input for connecting an instrument directly to the rear panel, or for connecting the Quartet to an unbalanced patch bay.The input impedance of this jack is 1M when the DI input switch on the front panel is set to Instrument, or 100K with a 20dB pad when the DI input switch is set to Line.

Mic/DI Insert

Send or MIC/DI Direct Out:
Use this jack to obtain a direct output from the Mic/DI preamp, or to send the Mic/DI preamp signal out of the Quartet for outboard processing. This jack is normalled to the Mic/DI insert Return.

Return or External Preamp In: Use this jack to patch an external preamp into the Quartet, or to return the Mic/DI preamp signal into the Quartet after outboard processing. This jack is normalled to the Mic/DI insert Send.

EQ In/Out: Use these jacks to patch the tube EQ out for external processing. Make sure the IN/BYPASS switch on the front panel is in BYPASS.

Opto/DS In/Out: Use these jacks to patch the Opto-compressor/De-Esser out for external processing. Make sure the IN/BYPASS switch on the front panel for the Opto-compressor is in BYPASS. To use the De-Esser, put the IN/BYPASS switch in the 'IN' position.

Opto/DS Link: A TRS jack for linking two Quartet compressors for stereo operation. Linking requires a TRS 'crossover' cable, in which the tip and ring connections are inverted on the opposite side of the cable.

Main Outputs

Transformer-Balanced: A male XLR connector with Pin 1 = ground, Pin 2 = + phase, Pin 3 = - phase. Connect this output to 3 pin balanced console, converter, or tape input.

Unbalanced: A 1/4" jack with Tip = + phase, Sleeve = ground. Use it for connecting the Quartet to an unbalanced input, or to a balanced input with Tip = pin 2, Ring = pin 3, Sleeve = ground.
NOTE: The transformer-balanced XLR output is DISABLED when using the unbalanced output.

AC Power

AC IN: On the left side of the rear panel is the IEC input socket. Connect to a 120V/60Hz or 230V/50Hz receptacle with the 3 prong IEC power cable.

Voltage Selector (115/230V): Set the ac voltage switch for the correct line voltage before connecting the Quartet to the ac line. For safety reasons, do not lift the ground on the power plug by using a 3-to-2 ground lift adapter.

Fuse: If necessary, replace the 1.5A/250V (5x20mm) SLO-BLO fuse (inside the IEC input socket) only with the same type and rating.