Avalon VT-737SP
DIRECT SIGNAL PATH
The Avalon VT-737SP features a combination of TUBE preamplifiers, opto-compressor, sweep equalizer, output level and VU metering.
Features 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 and large control knobs. VU meter for output level monitoring and compressor gain reduction.
Preamplifier
The VT-737 has three input selections:
1. Transformer balanced microphone input, +48v phantom selection.
2. Instrument Dl high source input with jack located on front panel.
3. Balanced line input, discrete high-level Class A.
The high-performance 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.
Sweep-Equalizer and Output Level
The VT-737 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 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
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