Radial Engineering PowerTube Preamplifier

Radial Engineering PowerTube Preamplifier

Radial Engineering PowerTube Preamplifier

B&H # RAPOWERTUBE MFR # R700 0115
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Expected availability: 7-10 business days

Product Highlights

  • High-Voltage 12AX7 Tube Drive
  • 60dB Gain
  • Smooth-Sounding Jensen Transformer Input
  • 100% Discrete Class-A Electronics
  • Single-Wide Module
  • Fits All 500 Series Rack Formats
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  • 1Description

The Radial Engineering PowerTube Preamplifier 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 that is characteristic of a Jensen transformer. The signal is then amplified via a select 12AX7 tube using an innovative, non-radiating charge pump that supplies 140V 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 suitable 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 Preamplifier is equipped with fully variable trim and gain controls. A 10-segment LED bar graph provides visual feedback. Driving the PowerTube Preamplifier 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 Preamplifier comes factory-loaded with a select 12AX7 tube along with a second Tonebone distortion pedal tube for more grit and madness.

10-Segment LED
Provides visual signal status as it monitors average RMS peaks to deliver a clean, distortion-free signal to the mix buss and recording system.
Trim
The Trim control lets you set the input level going to the tube and class-A circuit. Set low for least distortion or high to add harmonic content and grit.
180° Polarity Reverse
Used to phase-align 2 signals for greater accuracy or as a creative element during the recording process.
Gain
Lets you adjust the overall drive circuit. When pushed hard, the PowerTube adds character and harmonics to the signal path.
Air
High-frequency lift used to gently add presence to the signal path for more shimmer and clarity.
Filter
The 80 Hz high-pass filter removes low frequencies to help eliminate excessive bass. It is particularly useful when layering acoustic tracks.
48V
Phantom power for condensers is equipped with power-on LED and recessed to prevent accidental use that could damage ribbon mics.
Mic Input
The XLR female connector is conveniently located on the front panel and placed at the bottom to keep the cable out of the way.
Omniport
Rear-mounted 1/4" instrument input, allows guitar and bass to be recorded direct. It is available when used with 500 series racks.
Full Enclosure
100% steel casing reduces magnetic interference from other nearby modules that may cause pollution.
100% Discrete Class-A
Output stage combines with the transformer and tube to deliver 60 dB of gain, making the PowerTube suitable for just about any microphone.
Radial Push Switches
Radial switches feature durable metal outer casing and are rated at over 20,000 cycles for added durability.
Double-Layer Front Panel
Steel construction adds rigidity to reduce stress on the PC board.
Dual Potentiometers
Doubled-up solder points for durability. Steel casing with steel shaft and retention nut will not bend when under stress.
Heavy Duty XLR
Glass-filled nylon connector with ultra-heavy nickel-silver solder lugs for optimal signal transfer and long-term reliability.
12AX7 Tube
The PowerTube employs a select low-noise 12AX7 tube with a non-radiating 140V charge pump to deliver the performance of a high-voltage tube preamp.
Gold-Plated 15-Pin Card Edge
Double sided to ensure positive connection to the receptacle for improved mating.
Jensen Transformer
Special high-performance Jensen input transformer delivers accurate frequency response and low noise, making it suitable for noise-prone vacuum tube preamps.
Power Assign Switch
Lets you toggle the input supply from the positive or negative rail. This enables multiple PowerTubes to be used without power sag.
Mil-Spec Circuit Board
Features double-sided PCB and full ground plane to assure lowest possible noise and durability for years of trouble-free performance.
Applications
PowerTube Preamplifier for Studio Vocals (In Cube)
The PowerTube Preamplifier is the front end for your finest studio microphone. The Jensen transformer-coupled front end quietly delivers the full spectrum of the source into the class-A tube drive circuit for great results.

Live Recording (In Workhorse without Mixer)
The single-wide design and innovative powering scheme allows you to use 8 PowerTube Preamplifiers in the Workhorse without sacrificing dynamic range. This makes it suitable for the most demanding live music recording sessions.

PowerTube on Bass (In PowerStrip)
Connect a bass to the Omniport instrument input on the Workhorse, Cube, or PowerStrip. Feed the PowerTube into a Komit compressor for dynamic control and then a JDX amplifier and speaker simulator to capture the sound of a 4x12 half stack.
UPC: 676101040476
In the Box
Radial Engineering PowerTube Preamplifier
  • Limited 3-Year Warranty on Parts & Labor
  • Table of Contents
    • 1Description
    Microphone Inputs
    Circuit Type 100% discrete class-A with 12AX7 tube drive
    Microphone Input Transformer coupled, Jensen JT-115KE
    Current Draw 235 mA
    Input Impedance 900 Ω
    Frequency Response 20 Hz to 20 kHz +0/-1 dB
    Gain Mic Preamp Gain: 60 dB
    Maximum Gain 75 dB when used with Workhorse rack and mixer
    Maximum Output 22 dBu
    Output Impedance 200 Ω
    Output Type 100% discrete class-A FET
    Common Mode Rejection >84 dB
    Equivalent Input Noise -128 dBu at maximum gain
    Dynamic Range >93 dB
    Total Harmonic Distortion 0.05%
    Intermodulation Distortion 0.011%
    Instrument Inputs
    Input Impedance 150 kΩ, unbalanced, when used with Workhorse rack and mixer
    Gain Instrument Preamp: 55 dB, unbalanced, when used with Workhorse rack and mixer
    Equivalent Input Noise -95 dBu, unbalanced, when used with Workhorse rack and mixer
    Total Harmonic Distortion 0.1%
    Control Panel
    Meter 10-segment peak indicator with hold
    Pad Variable
    Polarity Variable
    General
    High-Pass Filter 250 Hz cut-off, -3 dB at 150 Hz
    Control Presence boost at 5 kHz
    Phantom Power 48 VDC: 10 mA (as supplied by 500 frame)
    Configuration XLR: AES spec: pin-1 ground, pin-2 (+), pin-3 (-)
    Lift Ground Lift (Rear Panel): Lifts ground on front panel XLR input only
    Mechanical
    Compliance API & WHOS-Doc
    Weight 1.5 lb (0.7 kg)
    Packaging Info
    Package Weight 1.95 lb
    Box Dimensions (LxWxH) 8.9 x 6.7 x 1.4"

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