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Review: Avalon VT-737sp

Submitted On August 1, 2013 by Contributor:



Build Quality

Ease of Use


Overall Value

Total Score

91/ 100

Review Details

Price: $2475.00


  • Easy to use
  • Clean gain
  • Fast acting opto tube compressor
  • Clean and to the point EQ
  • Detailed DI for electric guitar and bass
  • Gets the job done





  • Tubes wear out more often than other tube preamps (Four dual triode Sovtek 6922 vacuum tubes)
  • Signal to noise ratio varies with certain microphones and low level sources
  • Signal breaks up undesirably when input or output stage is overloaded
  • Units can develop quirks if not properly maintained (you’ll understand what I mean once you’ve used one that has been ridden hard and put away wet)



My Review

A clean and detailed mono Class A dual triode vacuum tube preamp focused channel strip. (most of the time)

 A go to on lead vocals and acoustic guitars.  I prefer to use the high pass filter around 70HZ-90HZ depending on the microphone, vocalist or acoustic guitar.  Works very well for this purpose paired with a U87, Manley Reference Cardioid, M147, AKG 414 and even a Sony C800.  I prefer to use the compressor engaged post eq with a fast atk, fast release and somewhere around a 4:1 ratio which allows me to approach 0 db’s on the input stage and get some color out of the unit without fear of overloading the output.  I normally do not adjust the eq, but like the sound of the unit better when the eq circuity is engaged.  When gain is considerably lower than 0 db’s the unit acts as a very clean and detailed mono preamp (considered by some to be “too vanilla”)  I like the fact I have a choice between how much character I get out of it based on the amount of gain I feed the input.  As a Bass DI it is solid and detailed as well, the low shelf on electric bass does the trick to fatten up the bottom while using the high pass filter on the input to clean up some of the extraneous sub energy.  I normally dedicate this preamp to my vocal front end if I do not have the option for a Neve 1073, Rupert Neve 517 or an API 512 b or c.  While not always my first choice, this piece has a reputation for a reason.. IT GETS THE JOB DONE WELL!

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 Microphone26dB@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 to20dB
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)
Weight 22lbs (10kg)
Dimensions-shipping carton 21 x 18 x 8 in (533 x 457 x 203mm)
Weight-packed 26lbs (11.8kg)



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About The Contributor

Gennaro Schiano

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