Dbx 676 Tube Microphone Preamp Channel Strip - Long & McQuade Music Educator Site
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dbx 676 Tube Microphone Preamp Channel Strip

Departments > Pro Audio & Recording > Channel Strips > dbx > 676 Tube Microphone Preamp Channel Strip
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SKU: # 451935
Model: #



The dbx 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. 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.


• 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


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 Jack
Input Type: (instrument) Unbalanced
Instrument Input Impedance: 500 k Ω
Max Input: (instrument) +21dBu unbalanced
Preamp Insert Connector: Tip-Ring-Sleeve , RF filtered
Preamp Insert Type: Unbalanced, Tip = send, Ring = return
Line Outputs (Preamp & Compressor/Limiter) Connector: Male XLR and Tip-Ring-Sleeve (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 , 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 InputSelects between microphone XLR input and front panel 1/4" instrument input
Preamp Function Switches/Controls: +48VSends +48 VDC through 6.81 kΩ resistors to pins 2 and 3 of the microphone input
Preamp Function Switches/Controls: 20dB PadAttenuates the microphone input by 20 dB
Preamp Function Switches/Controls: Polarity InvertReverses pins 2 and 3 of the microphone input XLR
Preamp Function Switches/Controls: 80 Hz Low CutEnables 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 IndicatorIlluminates 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: NarrowSelects 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 (H x W x D): 3.5" X 19" X 8" (88.9mm X 482.6mm X 203.2mm)
Weight8.1 lbs (3.7 kg)
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