DBX 676 Tube Microphone Preamp Channel Strip

We at dbx Professional Products are proud to introduce the all new 676 Tube Mic Pre Channel Strip. The 676 represents all of the best of dbx’s more than 40 years of dynamics processing.
The 676 offers a pristine high-voltage, Class-A tube preamp section that runs on 250 volts, so your signal can be as crystal clean or dirty as you need it to be. The 676 also incorporates the compressor/limiter design from the highly-sought after dbx162SL, as well as a 3-band parametric EQ with sweepable mids.
The 676 provides audio professionals with the perfect channel strip for recording and live applications alike with its military-grade build and vintage-inspired controls, VU metering and state-of-the-art optional digital output card.

Key Features

• Class-A Vacuum Tube Preamp with High Voltage Gain
• High-Visibility Vintage VU Meter
• Compressor designed from the dbx162SL
• 3-Band Semi-Parametric EQ
• 1/4” and XLR Inputs and Outputs
• Front Panel Instrument Input
• Side Chain Insert

Technical Specifications

Mic Preamp Connector Female XLR Pin 2 Hot; Electronically balanced/unbalanced
Mic Preamp Input Impedance 1.9 kΩ
CMRR >85 dB from 20 Hz to 3 kHz, >70 dB from 3 kHz to 20 kHz
Instrument Input Connector Tip-Sleeve ¼” Jack
Input Type (instrument) Unbalanced
Instrument Input Impedance 500 k Ω
Max Input (instrument) +21dBu unbalanced
Preamp Insert Connector Tip-Ring-Sleeve ¼”, RF filtered
Preamp Insert Type Unbalanced, Tip = send, Ring = return
Line Outputs (Preamp & Compressor/Limiter) Connector Male XLR and Tip-Ring-Sleeve ¼” (Pin 2 and Tip hot)
Line Outputs (Preamp & Compressor/Limiter) Type Servo-balanced/unbalanced
Line Outputs (Preamp & Compressor/Limiter) Impedance Balanced 30 Ω, unbalanced 15 Ω
Line Outputs (Preamp & Compressor/Limiter) Maximum Output Level > +21 dBm (into a 600 ohm load)
Compressor Sidechain Insert Connector Tip-Ring-Sleeve ¼”, RF filtered
Compressor Sidechain Insert Type Unbalanced, Ring = output, Tip = input
Compressor Sidechain Insert Impedance 1 kΩ (output), 50 kΩ (input)
Vacuum Tube Type 12AU7A / ECC82
Vacuum Tube Grid Power Supply +250V DC
Vacuum Tube Heater Power Supply +12V DC
Frequency Response (Mic Input) 20 Hz to 50 kHz, +0/-1dB, 40 dB gain
Frequency Response (Instrument Input) 30 Hz to 70 kHz, +0/-1dB, unity gain
THD + Noise (Mic In to LIne Out) 0.25% typical at 0 dBu out, 1 kHz, 40 dB gain
THD + Noise (Instrument In to Line Out) 0.2% typical at 0 dBu out, 1kHz, unity gain
Equivalent Noise Level Typically > -123 dBu with a 150 Ω source load, 22 Hz to 22 kHz
Noise Floor Mic Insert to Comp Output: <-93 dBu, unity gain, EQ flat and no gain reduction
Preamp Function Switches/Controls: Instrument Input Selects between microphone XLR input and front panel ¼” instrument input
Preamp Function Switches/Controls: +48V Sends +48 VDC through 6.81 kΩ resistors to pins 2 and 3 of the microphone input
Preamp Function Switches/Controls: 20dB Pad Attenuates the microphone input by 20 dB
Preamp Function Switches/Controls: Polarity Invert Reverses pins 2 and 3 of the microphone input XLR
Preamp Function Switches/Controls: 80 Hz Low Cut Enables an 80 Hz, 12 dB/octave high pass filter in the microphone and instrument signal path
Preamp Function Switches/Controls: Gain Control Range -∞ to +55 dB for Microphone Input; -∞ to +40 dB for Instrument Input
Preamp Function Switches/Controls: Post Tube Attenuation -∞ to 0 dB
Preamp Function Switches/Controls: Peak Indicator Illuminates RED when the Preamp is within 3 dB of clipping
EQ Low Frequency 100 Hz, Low-pass shelving filter
EQ High Frequency 10 kHz, High-pass shelving filter
EQ Mid Frequency Sweepable from 100 Hz to 8 kHz
EQ Function Switches/Controls: Narrow Selects the “Q” of the MID Frequency EQ. “OUT” position Q = 0.9; “IN” position Q = 2.9
EQ Gain (All Bands) Sweepable from –15 to +15 dB
Compressor Threshold Range -40 dBu to +20 dBu
Compressor Threshold Characteristic Selectable OverEasy™ or Hard Knee
Compressor Ratio Variable 1:1 to ∞:1; 60 dB maximum Compression
Compressor Attack/Release Modes Selectable Manual or Auto
Compressor Manual Attack Time Scalable program-dependent; Typically 400 dB/msec to 1 dB/msec
Compressor Manual Release Time Scalable program-dependent; Typically 4000 dB/sec to 10 dB/sec
Compressor Auto Attack Time Program-dependent, typically 15 ms for 10 dB, 5 ms for 20 dB, 3 ms for 30 dB
Compressor Auto Release Time Program-dependent, typically 120 dB/sec
Compressor Output Level Control Range -20 dB to +20 dB
Compressor Peak Indicator Illuminates RED when the Compressor/Limiter is within 3 dB of clipping
Limiter Type dbx PeakPlus™
Limiter Threshold Range -4 dBu to + 22 dBu (off)
Limiter Ratio ∞:1
Limiter Attack and Release Program-dependent
Power Supply Universal switch-mode
Operating Voltage 100 – 240 VAC, 50/60 Hz
Power Requirements 20 Watts
Fuse T2.5AL 250V
Turn-On Time Approximately 2 seconds
Dimensions 3.5”H X 19”W X 8”D (88.9mmH X 482.6mmW X 203.2mmD)
Weight 8.1 lbs (3.7 kg)
Shipping Weight 11.0 lbs (5.0 kg)