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Avalon VT-747SP- Stereo Compressor / EQ  From Avalon

Tube Stereo EQ/Compressor Combo that should live on everyone's 2 Bus chain

Avalon Design

What We Think

This is a very unique and versatile box that isn't for everybody, but when it works, it’s quite a hit! Originally designed as a piece to warm up the nasty sterility and thinness of digital audio work stations, digital keyboards, synths, or even drum machines, the 747 is a very versatile stereo compressor and program EQ, featuring a distinctive tube sound. One great thing about the 747 is its variable saturation (the user can engage or disengage part of the tube section - a really cool and innovative feature). It also allows the user to touch up EQ'ing with simplicity (no fear about butchering a mix late in the night as with a parametric) and features a very controllable compressor. The box is a little tricky to work with at first, but with a little work, you'll be internally side-chaining with the best of them!

Manufacturer's Description from Avalon

The Avalon VT-747SP combines a creative STEREO tube-discrete Class A spectral-opto-compressor with a musical six band program equalizer, L-R output level and gain reduction metering and internal regulated power supplies in a 2U space. Ideal for high performance DAW input signal conditioning, stereo buss compression-EQ, stereo keyboards and analog mastering applications.

The opto-compressor features a minimum signal path design utilizing sealed silver relays for all signal routing and by pass functions. The optical attenuator acts as a passive level controller with a Class A, variable gain make-up amplifier. Full dynamic control from soft compression to hard-knee limiting can be achieved with master threshold, ratio-compression, attack and release controls. Gain reduction indication is a large analog VU meter. Low frequency and high frequency contour parametric spectral controls can be routed into the side-chain path for enhanced frequency dependent compression with variable frequency and threshold levels. SC listen provides side-chain listen mode for monitoring.

The VT-747SP equalizer utilizes 100% discrete, Class A high-voltage transistors for optimum sonic performance. The six band STEREO program EQ incorporates the smooth characteristics of an all passive design. The frequency turnover, Q and amplitude ranges have been carefully chosen for each band to provide the most natural harmonic balance and lowest phase change while offering simple and effective tone control. The EQ can be placed pre or post the opto-compressor for enhanced effects.

The VT-747SP features TSP which gives you the choice of either tube tone or the classic, Class A discrete transistor sound by exchanging, three (3) high-voltage dual triode tubes with discrete amplifiers in the opto-compressor and primary output stages.

Fully balanced DC coupled, Class A discrete amplifiers are utilized for the input and output drive interface with+36dB input headroom. A high quality analog VU meter indicates accurate gain reduction. Twin 60dB range LED meters provide fast L-R output status of all levels.

  • Stereo Class A opto-compressor with spectral control
  • Stereo Class A six band discrete passive program EQ
  • TSP twin signal path, vacuum tube bypass
  • Low noise -92dB
  • Fully balanced Class A input and DC coupled outputs
  • Stereo dynamic 60dB high resolution output meters
  • High quality analog VU meter for gain reduction
  • High headroom+36dB input before overload
  • Spectral side-chain monitor for pre listen
  • EQ pre-post selection for opto-compressor
  • Sealed silver relays for all signal routing
  • Internal discrete regulated power supplies
  • Military spec vacuum tubes for long life and low noise
Avalon Design

About Manufacturer

Wynton R. Morro founded Avalon with the desire to bring the art of music recording closer to the essence of the original performance. Avalon's pure Class A recording systems provide the world's leading engineers, producers and musicians with state-of-the-art electronics designed especially for high-fidelity music and sound recording, These carefully engineered systems enhance the creative senses and become one with the music itself. Avalon systems utilize 100% discrete, high-bias pure Class A audio amplifiers. These pure Class A amplifiers are incorporated into minimal signal path designs which include sealed silver relays, balanced DC coupled high-current "outside-world" drivers, fully discrete linear DC regulators, low noise toroidal power transformers and selected high quality active and passive components. This powerful combination of design features gives increased musical headroom and greater dynamic transient capability for a truly transparent audio passage. Avalon's unique design features, highest quality components and continued pursuit of sonic excellence assures the most harmonious musical signal transfer available today. Whether you are recording a solo vocalist, capturing the delicate nuance of an acoustic instrument, mastering music and film productions or recording symphonies, let Avalon take you to the leading edge in analog and experience sonic reality like never before!


Circuit topology: Three (3) dual triode vacuum tubes (Sovtek 6922), high-voltage discrete Class A mode.

Input gain range: Balanced, Class A, 20k ohms, -20dB to +16dB with high gain switch

Maximum input level: +36dB balanced XLR pin 2 hot

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

Output type: XLR connector, output trim gain -45dB to +6dB

Noise 20kHz unweighted: -92dB

Distortion THD, IMD: 0.5%

Frequency response -3dB: 1Hz to 200kHz

Gain reduction meter: High quality, illuminated gain reduction meter 0dB to -20dB range

Output meter: Twin 20 segment LED VU meters with -27dB to +30dB range

Compressor type: Optical passive attenuator

Make-up gain: Variable 0dB to +10dB stereo tracking

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

Side-chain spectral contour: Variable threshold -15dB to +15dB, frequency 70Hz to 9kHz twin ranges

Equalizer type Discrete: Class A, passive design optimized for full range program material

Frequency bands (6):   Variable amplitude LF +/-24dB 15Hz shelf response
Variable amplitude MF1 +/-8dB 125Hz selected Q response
Variable amplitude MF2 +/-4dB 500Hz selected Q response
Variable amplitude MF3 +/-4dB 2kHz selected Q response
Variable amplitude MF4 +/-10dB 5kHz shelf response
Variable amplitude HF +/-20dB 32kHz shelf response

AC power: Internal toroidal 100v to 240v, 50-60Hz selectable, 70 watts maximum

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

Weight: 22lbs (10kg)

Dimensions-shipping carton: 21 x 18 x 8 in (533 x 457 x 203mm)

Weight-packed: 26lbs (11.8kg)





VT-747SP Quick Setup Sheet

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