Specs & Downloads

Item# DBX676MX


The Pedigree of Professional Audio

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, vintage-inspired controls and VU metering.

General Specifications

Mic Preamp Connector
Female XLR Pin 2 Hot; Electronically balanced/unbalanced
Mic Preamp Input Impedance
1.9 kΩ
>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
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
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
Limiter Attack and Release
Power Supply
Universal switch-mode
Operating Voltage
100 – 240 VAC, 50/60 Hz
Power Requirements
20 Watts
T2.5AL 250V
Turn-On Time
Approximately 2 seconds


3.5 in (88.9 mm)
19 in (482.6 mm)
8 in (203.2 mm)
8.1 lbs (3.7 kg)
Shipping Weight
11.0 lbs (5.0 kg)

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