Avalon Design VT-737sp Tube Channel Strip (Gold Edition)

Preamplifier Stage

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 single-ended anode-coupled followers. A passive variable high-pass filter and hard-wired relay bypass completes the input signal conditioning. The phase reverse relay is available on all three inputs.

• High-performance microphone input with transformer balancing and +48V phantom power selection
• Instrument DI Hi-Z input with front-panel 1/4" jack
• Balanced XLR-1/4" combo line input with discrete, Class-A circuitry

Optical Compressor

The opto-compressor features a minimal 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 optimal 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. When the EQ to side-chain 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.

Extra Features

• Four dual-triode Sovtek 6922 high-voltage Class-A vacuum tubes
• High-voltage circuits for maximum headroom of +30 dB
• Low self-noise of just -92 dB
• Internal discrete switching power supply with toroidal transformer
• Soft-start tube life extender
• Stereo link connection for compressors
• Sealed silver relays for signal routing on all bypass relays
• Large control knobs with professional conductive plastic potentiometers
• VU meter for output level monitoring and compressor gain reduction down to -20 dB

Avalon Design VT-737SP Specs

Audio Circuit Type	Analog (Solid-State and Tube)
Gain Control	0 to 58 db (Microphone) -27 to 28 dB (Balanced Line) 0 to 30 db (Unbalanced Instrument)
Output Gain	-45 to 20 dB
Maximum Output Level	+30 dB (Balanced, DC Coupled)
Noise	-92 dB (at 20 kHz)
EIN	-116 dB (22 Hz to 22 kHz)
THD	0.5%
Frequency Response	10 Hz to 120 kHz (-2.5 dB) 1 Hz to 200 kHz (-3 dB, Line I/O)

Audio I/O

1x XLR 3-Pin Mic Input (Balanced) 1x Combo XLR-1/4" TRS Line Input (Balanced) 1x 1/4" TS Hi-Z/Instrument Input (Unbalanced) 1x XLR 3-Pin Line/Mic Output (Balanced) 1x 1/4" TRS Output (Compressor Stereo Link)

Power Source	AC Input
AC Input Power	Changing Voltage Requires Manual Switching 100 to 240 VAC, 50 / 60 Hz
Power Consumption	75 W (Maximum)

Mounting	Front: 4x Standard Rack Screw
Color	Gold
Material of Construction	Metal, Plastic
Dimensions	19 x 12 x 3.5" / 48.3 x 30.5 x 8.9 cm
Weight	22 lb / 10 kg