The Avalon VT-737SP is an amazing preamp/channel strip with a combination of tube preamplifiers, opto-compressor, sweep equalizer, output level and VU metering, all in a 2U space. This is the choice processor for many voice-over artists.The VT-737SP has three input selections: 1. The VT-737SP features a higher-performance microphone input transformer with +48v phantom selection. 2. Instrument DI high source input with jack located on front panel. 3. Balanced line input, discrete high-level Class A. The Class A preamplifier utilizes two cascaded, dual vacuum tube triodes configured with minimum negative feedback. A high gain switch boosts the overall gain of the preamplifier. The four high quality tubes are configured as singled ended anode coupled followers. A passive-variable high pass filter and hard-wire relay bypass completes the input signal conditioning. The phase reverse relay is available on all three inputs.The opto-compressor features a minimum signal path design with twin Class A vacuum tube triodes for gain matching. The optical attenuator acts as a simple passive level controller. Full dynamic control from soft compression to hard- knee limiting can be achieved with threshold, ratio-compression, attack and release controls plus gain reduction selection on the large VU meter. Special spectral control including de-ess is available with the dual sweep mid EQ to side-chain switch. The EQ section can be flipped pre or post the opto-compressor via a front panel switch for alternate effects and tone shaping. Two VT-737SPs can be linked via a rear panel link cable for stereo tracking. The compressor bypass is a sealed silver relay for the most direct signal path.The VT-737SP equalizer utilizes 100% discrete, Class A-high-voltage transistors for optimum sonic performance. The high and low frequency bands provide the smooth characteristics of an all passive design, while the dual mid bands include variable frequency and switched Q-width selection. The enhanced range of the mid bands is extended into the high and low bands by the use of X10 frequency multipliers. The bypass switch incorporates a sealed silver relay for the most direct signal path. When the EQ to sidechain is engaged, the high-low EQ remains in the audio path for “tone enhancement”. The output level control provides a variable control of the overall signal path. The output amplifier utilizes another dual triode vacuum tube driving a 100% discrete, Class A, high-current, balanced and DC coupled low noise output amplifier.Features:Vacuum tube triode signal pathTransformer balanced microphone inputHigh-voltage circuits for maximum headroom to +30 dB/ Internal discrete power supply with toroidal transformerSoft-start tube life extenderStereo link for compressorsAll discrete Class A equalizer with musical passive filter designSealed silver relays for signal routingLarge control knobs with professional conductive plastic potentiometersVU meter for output level monitoring and compressor gain reductionFour dual triode vacuum tubes (Sovtek 6922), high-voltage discrete Class AGain Range, Microphone: Transformer balanced 850/2500 ohm, 0 dB to +58 dB; Instrument: Unbalanced 1 meg ohm, 0dB to+30 dB; Line: Balanced Class A 20k ohms, -27 dB to 28 dBMaximum input level and connector types: Microphone, 26 dB@25 Hz, +30 dB @ 1 kHz balanced XLR; Instrument, +30 dB unbalanced front panel jack socket; Line, +36 dB balanced XLRMaximum output level: +30 dB balanced, 600 ohms, DC coupled, discrete Class AOutput type and gain: XLR connector, output trim gain -45 dB to20 dBNoise, 20 kHz unweighted: -92 dBNoise microphone EIN: -116 dB, 22 Hz to 22 kHz unweightedDistortion THD, IMD: 0.5%Frequency response, -/2.5 dB: 10 Hz to 120 kHz, input filter includedFrequency response :-3 dB, 1 Hz to 200 kHz, line in-outVU meter and gain reduction: High quality illuminated OVU =+4 dB and gain reduction to -20 dBHigh cut filter: Variable 6 dB per octave, 30 Hz to 140 HzCompressor type: Optical passive attenuator incorporating twin vacuum tubes and stereo linkEqualizer type: Discrete Class A, variable active and switched passive design, 4-bandAC power : Internal toroidal 100v to 240v, 50-60Hz selectable, 75 watts maximumDimensions: 19 x 12 x 3.5 in.; 22 lbs (26 lbs shipping wgt)