AVALON VT737SP Channel Strip and Audio Technica AT4040 Microphone

The Avalon VT-737SP features a combination of TUBE preamplifiers, opto-compressor, sweep equalizer, output level and VU metering in a 2U space.

PREAMPLIFIER
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.

OPTO-COMPRESSOR
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.

SWEEP-EQUALIZER AND OUTPUT LEVEL
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.

• Circuit topology: 4 dual triode vacuum tubes (Sovtek 6922),high-voltage discrete Class A

• Gain Range Microphone: Transformer balanced 850/2500 ohm,0dB to +58dB Instrument: Unbalanced 1 meg ohm, 0dB to +30dB

• Line: Balanced Class A 20k ohms, -27dB to 28dB

• Maximum input level and connector types:Microphone26dB@25Hz, +30dB@1kHz balanced XLR Instrument+30dBunbalanced front panel jack socket

• Line +36dB balanced XLR

• Maximum output level: +30dB balanced 600 ohms, DC coupled,discrete Class A

• Output type and gain: XLR connector, output trim gain -45dBto20dB

• Noise 20kHz unweighted: -92dB

• Distortion THD, IMD: 0.5%

• Frequency response -2.5dB: 10Hz-120kHz input filter included

• Frequency response -3dB: 1Hz-200kHz line in-out

• VU meter and gain reduction: High quality illuminated OVU=+4dB and gain reduction to -20dB

• High cut filter: Variable 6dB per octave 30Hz-140Hz

• Compressor type: Optical passive attenuator incorporatingtwin vacuum tubes and stereo link

• Threshold - Ratio: Threshold variable -30dB to +20dB,ratio-compression variable 1:1 to 20:1

• Attack - Release: Attack variable 2mS to 200mS, releasevariable 100mS to 5 seconds

• Equalizer type: Discrete Class A, variable active andswitched passive design

• Frequency bands (4): Treble - switched 10kHz, 15kHz, 20kHz,32kHz, ﾱ20dB range, shelf High mid - variable200Hz-28kHz and 2kHz -28kHz, ﾱ6dB range, hi-lo Q Lowmid - variable 30Hz-450Hz and 300Hz-4k5Hz, ﾱ16dB range,hi-lo Q Bass - switched 15Hz, 30Hz, 60Hz, 150Hz, ﾱ24dBrange, shelf

• AC power: Internal toroidal 100v to 240v, 50-60Hzselectable, 75 watts maximum

• Dimensions: 19 x 12 x 3.5 in (482 x 305 x 89mm)

• Weight: 22lbs. (10kg)

The AT4040 side-address condenser microphone features an advanced large diaphragm tensioned specifically to provide smooth, natural sonic characteristics. A marriage of technical precision and artistic inspiration, the AT4040 offers exceptionally low noise, wide dynamic range and high-SPL capability for greatest versatility. This ultra-consistent microphone may be used with confidence in a wide variety of studio and live miking applications, even under the stringent demands of digital recording systems. The AT4040’s low-noise circuitry is symmetrical and transformerless, resulting in exceptional transient response and clean output signals for transparent reproduction of even the most troublesome of instruments and sound effects.

ELEMENT: Externally-polarized (DC bias) condenser

POLAR PATTERN: Cardioid

FREQUENCY RESPONSE: 20-20,000 Hz

LOW FREQUENCY ROLL-OFF: 80 Hz, 12 dB/octave

OPEN CIRCUIT SENSITIVITY: -32 dB (25.1 mV) re 1V at 1 Pa

IMPEDANCE: 100 ohms

DYNAMIC RANGE (typical): 133 dB, 1 kHz at Max SPL

SIGNAL-TO-NOISE RATIO: 82 dB, 1 kHz at 1 Pa

PHANTOM POWER REQUIREMENTS: 48V DC, 4.2 mA typical

SWITCHES: Flat, roll-off; 10 dB pad (nominal)

ACCESSORIES FURNISHED: AT8449 shock mount for 5/8"-27 threaded stands; microphone dust cover; protective carrying case

WEIGHT: 12.7 oz (360 g)