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Radial Powertube Tube 500-Series Preamplifier  From Radial

A rich, 3-dimensional 500 series tube preamp that can take a flat, uninspiring tone and turn it into a world-class recording. While the Powertube excels on any studio application and instrument, it's performance on male and female vocals is outstanding.

Radial Engineering


Retail:  $800.00

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Radial Powertube Tube 500-Series Preamplifier

The Radial PowerTube... the true character of a world class vintage tube preamp without the noise! A rich, 3-dimensional 500 series tube preamp that can take a flat, uninspiring tone and turn it into a world-class recording. While the Powertube excels on any studio application and instrument, it's performance on male and female vocals is outstanding. This Preamp is available for SoundPure's Try-Before-You-Buy Program, so if you want to hear how it sounds in your studio with your gear, shoot us an email at, or call us anytime at 919.682.5552. Thanks for watching!

  • Signal Chain
    • Radial Powertube Tube 500-Series Preamplifier

Manufacturer's Description from Radial

The Radial PowerTube is an 'old school' 100% discrete class-A vacuum tube microphone amplifier intended to capture the essence of the voice or instrument while adding the rich harmonics, warmth, and character of a transformer coupled tube circuit.

Designed to fit inside the Radial Workhorse and other 500 series racks, the 'single-wide' PowerTube begins with an ultra low-noise Jensen input transformer. This exhibits near perfect frequency response while producing the warm Bessel curve Jensen is legendary for. The signal is then amplified via a select 12AX7 tube using an innovative non-radiating charge pump that supplies 140 volts to the tube to deliver the excitement and character of a high-voltage vintage tube amplifier. This feeds a class-A balanced output stage that together, can produce as much as 60dB of gain. This makes the PowerTube ideal for use with all microphones.

Features include an easy-access front panel XLR input with a safely recessed 48V phantom power switch. To optimize signal-to-noise the PowerTube is equipped with fully variable trim and gain controls. A 10 segment LED bar graph provides visual feedback and driving the PowerTube into the red is encouraged. This increases the grit, harmonic content and distortion. For even more character, activating the Air adds a slight edge to a male vocal or sparkle on an acoustic guitar. Low frequency resonance is easily tamed using the high-pass filter. For added pleasure, the PowerTube comes factory-loaded with a select 12AX7 tube along with a second Tonebone distortion pedal tube for more grit and madness.

The Radial PowerTube... the true character of a world class vintage tube preamp without the noise!


Radial Engineering

About Manufacturer

Radial Engineering is a manufacturer and distributor of professional audio equipment, building tools for the working audio and audio-video professional. Radial is located on the Fraser River, just outside Vancouver, British Columbia in the municipality of Port Coquitlam. The company began operations in the fall of 1991 as the Canadian distributor of Mogami cable and Jensen Audio Transformers. In 1992, it became a limited corporation under the JP Cabletek Electronics Ltd. banner. The Radial name was first used on house branded cables and snake systems. The Radial name and logo represents a cross section of quad cable; Radial being round. In 1996 the Radial JDI direct box was launched. This led the way to the Radial JDV and today, over 50 electronic products are now being produced under the Radial, Tonebone and Forest Audio brands. In 2001, the Primacoustic brand was launched to address the growing demand for acoustic products for the burgeoning home recording market and in 2006, the company officially changed its name to Radial Engineering Ltd.



Microphone Input  
Circuit type: 100% discrete class A with 12AX7 tube drive
Microphone Input: Transformer coupled, Jensen JT-115KE
Current draw: 235mA
Frequency response: 20Hz ~ 20KHz +0/-1dB
Input Impedance: 900Ω
Mic preamp gain: +60dB
Maximum gain: +75dB when used with Workhorse*
Maximum output: +22dBu
Output impedance: 200Ω
Output type: 100% discrete Class-A FET
Common mode rejection (CMRR): >84dB
Equivalent Input Noise (EIN): -128dBu @ maximum gain
Dynamic range: >93dB
Total Harmonic Distortion (THD+N): 0.05%
Intermodulation distortion (IMD) 0.011%
Instrument Input  
Omniport input Impedance: 150kΩ, unbalanced*
Instrument preamp gain: +55dB, unbalanced*
Equivalent Input Noise (EIN): -95dBu, unbalanced*
Total Harmonic Distortion (THD+N): 0.1%
Control Panel  
Meter: 10 segment peak indicator with hold
Pad: Variable
Polarity: 180°
High-pass filter: 250Hz cut-off, -3dB at 150Hz
Air Control: Presence boost @5kHz
Phantom power: 48VDC - 10mA (as supplied by 500 frame)
XLR configuration: AES spec: pin-1 ground, pin-2 (+), pin-3 (-)
Ground lift (rear panel): Lifts ground on front panel XLR input only
Weight: 1.5lbs (0.7Kg)
Shipping size: 9 x 6.5 x 2 (inches)
Compliance (API): Yes
Compliance (WHOS-Doc): Yes
Warranty: 3 years, transferable