DBX 786 User Guide
8760 S. Sandy Pkwy.
Sandy, Utah 84070
Phone (801) 568-7660
Fax (801) 568-7662
Int’l Fax (801) 568-7583
customer@dbxpro.com
http://www.dbxpro.com
A Harman International Company
• 130dB Dynamic Range
• High-Drive output transformer drives 1000 ft. of Belden
at .007% THD
• +48V Phantom Power, Phase Reverse, -20dB Input Pad,
Super Low-Z input switch
• Proprietary High Frequency EQ circuit with cut/boost to
40kHz
18-1717-D 08/05
PRECISION MIC PREAMP
786
PRECISION MIC PREAMP
786
PRECISION MIC PREAMP
786
PRECISION MIC PREAMP
786
®
The craftsmanship of the 786 is as stunning as the engineering is innovative. Astriking blue front panel
machined from 1/4" aircraft aluminum, hand-crafted solid aluminum knobs, LEDs mounted individually in machined stainless steel housings, custom VU meters with peak indicators, and heavy gauge
chassis solidify the 786 as the benchmark preamplifier for decades to come. The 786 combines the best
preamplifier features and an absolutely pristine audio path. In addition to having +48V phantom power
as well as a phase reverse switch, the 786 also features a patent-pending EQ circuit called “spectrum”
with frequency cut and boost up to 40kHz. An 1 1-position coarse gain switch sets the gain between +10
and +60dB, while the fine gain control varies between -3 and +3dB. Levels may be monitored on peakprogram VU meters with adjustable reference levels. The signal path consists of a transformer-coupled, discrete-design premium input stage, utilizing the proprietary dbx M8™ Mic Pre-Amp Module.
“Spectrum”, a unique variable high-frequency equalization circuit employed in the mic pre-amp
enhances the high frequency spectral content of the signal while maintaining phase integrity. The
“Detail” control varies the amount of high frequency shelving boost at the frequency determined by
the Spectrum control. The combination of the Spectrum and Detail controls allow pristine high frequency equalization adjustments without the added “hash” of traditional high-frequency EQ topologies. Premium active electronics, precision 0.1% and 1% metal film resistors, great sounding temperature stable polypropylene capacitors, high-reliability board-to-board connectors with gold-palladiumnickel contacts, Jensen® transformers, gold plated Neutrik® XLRs, rare earth magnet relays with gold
contacts in a hermetically sealed nitrogen environment, military grade glass epoxy circuit boards, to
mention a few, contribute to the most technologically advanced preamplifier in the world.
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FOR MORE INFORMATION CONTACT:
dbx Professional Products
8760 S. Sandy Pkwy.
Sandy, Utah 84070
Phone (801) 568-7660
Fax (801) 568-7662
Int’l Fax (801) 568-7583
customer@dbxpro.com
http://www.dbxpro.com
A Harman International Company
The dbx Blue Series Solid State 786 Mic Pre-Amp is a 2U twochannel precision mic pre companion product to the 160S Stereo
Compressor/Limiter. We refer to this as a “precision mic pre-amp”
as it is designed to provide the truest reproduction of the microphone source as is electronically possible, as opposed to “FX” mic
pre-amps. The pre-amp features the ubiquitous +48V phantom
power, 20dB pad, and phase invert functions, but also includes a
switchable “super low Z” setting which optimizes the pre-amp performance for microphones with very low source impedance. An
11-position coarse gain switch sets the gain between +10 and
+60dB, while the fine gain control varies between -3 and +3dB.
Levels may be monitored on peak-program VU meters with
adjustable reference levels.
The signal path consists of a transformer-coupled, discrete-design
premium input stage utilizing the proprietary dbx M8™ Mic PreAmp Module. The minimum signal path design routes the amplified signal directly to a patented high output drive circuit. Each
stage throughout the mic pre-amp is small-signal square wave compensated to assure precise phase alignment at all audio frequencies.
Two output options will be available for the mic pre; an analog card
that parallels one extra high drive output per channel acting as a
premium signal splitter, and a dbx Type IV Conversion System‘
card that provides proprietary analog-to-digital conversion for both
channels with both AES/EBU and S/PDIF outputs.
The dbx Blue Series Solid State Mic Pre has patented high-precision, high-drive, transformer-coupled output stages capable of performing with incredible accuracy and sonic
transparency in virtually any audio environment. The custom designed transformer, coupled with a discrete distortion canceling driver circuit, is capable of driving 1000 feet of
Belden 8451 cable terminated with a 150 ohm load, while maximum drive levels exceed
+30 dBm. Yet this output stage exhibits remarkably low distortion levels, immeasurable
using standard audio test equipment.
dbx engineers are constantly working to improve the quality of our products.
Specifications are, therefore subject to change without notice.
dbx 786 Mic Preamp
Input Specifications
Gain +10 to +60 dB in 5 dB
steps
Phantom Power +48V regulated
Pad 20 dB
Equivalent Input Noise -132 dBu
THD >0.002%
Input CMRR >100 dB
Bandwidth > 200kHz
Detail 16 dB boost/cut at fre-
quency determined by
the Spectrum control
Spectrum Variable from 5 kHz to
40kHz
Output Specifications
Output Drive Capability > +30 dBm
Output Stage THD Immeasurable at
+4dBu
Earth Potential Isolation >200 Volts DC
Output CMRR 110 dB
Bandwidth >200kHz
Overall Unit Specifications (Preliminary)
Dynamic Range >130 dB
Head Room 26 dB reference =
+4dBu
Signal to Noise 104 dB reference =
+4dBu
THD + Noise 0.002%
Frequency Response +0/-3 dB 2Hz - 200kHz
maximally flat phase
response. +0/-0.25 dB
20Hz - 20kHz
Deviation from Linear Phase < 0.5∞20Hz -
20kHz
Power Supply Rails +/- 24 Volts low noise
regulated supply
Power Transformer 60 VA Toroidal in 30dB
mu-metal enclosure
Physical
Dimensions: 3.5''Hx19''Wx8''D
Weight: 20.5 lbs. (9.3kg)
Shipping Weight: 25 lbs (11.3 kg)
Note: 0 dBu = 0.775V RMS
PRECISION MIC PREAMP
786
PRECISION MIC PREAMP
786
786
PRECISION MIC PREAMP
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MANUFACTURED UNDER THE FOLLOWING U.S. PATENTS:
4,368,425 5,282,252. OTHER PATENTS PENDING.
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