The Avalon VT-737SP features a combination of TUBE preamplifiers, opto-compressor, sweep equalizer, output level and VU metering in a 2U space.
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.
Vacuum tube triode signal path, transformer balanced microphone input, high-voltage circuits for maximum headroom to +30dB, low noise -92dB, internal discrete power supply with toroidal transformer, soft-start tube life extender, stereo link for compressors, all discrete Class A equalizer with musical passive filter design, sealed silver relays for signal routing, large control knobs with professional conductive plastic potentiometers, VU meter for output level monitoring and compressor gain reduction.
|Circuit topology||Four 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|| Microphone: 26dB@25Hz, +30dB@1kHz balanced XLR Instrument+30dB unbalanced 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 -45dB to 20dB|
|Noise 20kHz unweighted||-92dB|
|Noise microphone EIN||-116dB, 22Hz to 22kHz unweighted|
|Distortion THD, IMD||0.5%|
|Frequency response -/2.5dB||10Hz to 120kHz input filter included|
|Frequency response -3dB||1Hz to 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 to 140Hz|
|Compressor type||Optical passive attenuator incorporating twin 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, release variable 100mS to 5 seconds|
|Equalizer type||Discrete Class A, variable active and switched passive design|
|Frequency bands (4)||Treble - switched 10kHz, 15kHz, 20kHz, 32kHz, +/- 20dB range, shelf High mid - variable 200Hz to 2k8Hz and 2kHz to 28kHz, +/- 16dB range, hi-lo Q Low mid - variable 30Hz to 450Hz and 300Hz to 4k5Hz, +/- 16dB range, hi-lo Q Bass - switched 15Hz, 30Hz, 60Hz, 150Hz, +/- 24dB range, shelf|
|AC power||Internal toroidal 100v to 240v, 50-60Hz selectable, 75 watts maximum|
|Dimensions||19 x 12 x 3.5 in (482 x 305 x 89mm)|