MACKIE MDB-1A ACTIVE DIRECT BOX

Product Highlights

• Connect an Instrument to a Mic Input
• Converts Unbalanced to Balanced
• Converts High Impedance to Low Impedance
• 1/4" Unbalanced Input
• 1/4" Thru Jack
• XLR Balanced Output
• Switchable Pad Prevents Overloading
• Ground-Lift Switch Minimizes Hum
• Merge, Low-Cut, and Polarity Switches
• Operates on Phantom Power

Active DI-Box SM-60

The electronic Direct-Injection Box SM-60 allows direct connection of electronic
music instruments such as keyboards, synthesizers, electric and electronic pianos,
etc. with mixing consoles in PA-systems and in recording studios.
The SM-6 is designed for applications, where a passive DI-Box does not perfom
satisfactorily, i.e., where the output level of a passive DI-Box is too low for the microphone
input section of the mixing desk.
Because the input impedance of the SM-6 is above 5 MOhm, instrument outputs are
not loaded or in any other way adversely affected. The voltage ratio from input to output
is 1: 1 and is always sufficient for connection with any microphone input. Input connectors
are 1/4" phone jacks, output connector is a Switchcraft D3M; output is 600 Ohms,
transformer balanced. The output level may in certain cases overload microphone inputs -
the line input section of the mixing console must then be used for connecting the SM-6.
The unit operates with a 9 V battery or phantom powering from 24 to 48 volts.

Technical Data

input impedance > 5 MOhm
max. input impedance + 6 dBu, 1,55V
ouptut impedance 600 Ohm
frequency response 20 ... 20000 Hz, ± 0,2 dB
gain 1 : 1
THD < 1 % at 30 Hz
       < 0,7 % bei 40 Hz
powering  9-V battery (IEC 6LF22) or
                 phantom power 24 ... 48 V.
inputs  two 1/4" phone jacks , unbalanced
          (one being used as output to instruments amp)
outputs  XLR, balanced
             pin 1 = ground, pin 2 = hot, pin 3 = cold
case aluminium die-cast
weight 240 g
dimensions 113 x 71 x 37 mm

The AC 275 is an active, phantom powered direct box. Unlike a passive DI where the frequency response of the signal can be altered depending on the connected impedance, an active DI buffers the input signal with an amplifier. This assures that the sound source will reach the mixer balanced and noise-free.

Housed in a cast alloy chassis, the AC 275 supplies two, high impedance, unbalanced 1/4" jacks and one low impedance balanced XLR jack. It operates with battery or phantom power.

Key Features
?	Active direct box
?	Allows a hi impedance unbalanced source to directly feed a low impedance balanced input
?	Flat frequency response
?	Connects guitar pickups, microphones or electric instruments to a recording or P.A. console without audio quality loss
?	Internal pad for speaker level input
?	Operates with battery or phantom power
?	Ground lift switch eliminates typical ground loop problems
?	Rugged, road-proof cast alloy chassis

2-channel DI box/splitter, passive Converts 2 separate unbalanced line inputs (e.g. instruments) into 2 balanced XLR outputs for connecting a mixer Switchable to split mode (input 1 routes the signal to both outputs) Switchable input attenuation: 0 dB, -20 dB, -40 dB Ground-lift switch eliminates ground loop problems 2 signal inputs via XLR/jack combo connectors 2 low-impedance XLR outputs Modern convex housing design Full rubber housing corners for safe operation Cables can be routed under the housing

Tube-buffered DI-Box DI-1000

The Tube-Buffered DI-Box DI-1000 allows the extraction of all the musical details of
musical interfaces without degrading the sound. This can only be achieved by
providing a very high input impedance to avoid any loading of instrument pickups.This
design approach allows seemingly infinite headroom to preserve the real dynamic range
of the interfaced instruments.A vacuum tube enables all these goals to be achieved
without any compromises in sound quality.The sonic difference between a standard
DI-Box and the Tube-Buffered DI-Box is comparable to the musical resolution difference
between a standard microphone and a studio microphone.One of the best transformers,
the very transparent sounding JENSEN JT-DB-E, was chosen providing complete ground
isolation. The parameters of this transformer, like frequency response, phase response,
group delay and geadroom capabilities, play a vital part in the performance of this DI-Box.
 
Technical Specifications
Input
The signal of the instrument is directly fed to the tube circuit with > 20 MOhms input
impedance to prevent any signal degradation, inevitable in traditional designs.
Buffered Output“
The second stage of the vacuum tube is used to buffer the signal and lower the output
impedance to < 8 kOhms. This unity gain output allows for cable runs of 10 meters
without loosing high frequency information.
Boost circuit
The boost circuit increases the signal send to the output transformer by 15 dB. This may
be useful for instruments with extremely low output, but decreases headroom capability
to 6 Volt rms. Under these circumstances the signal may be clipped, concerning the output
transformer?s signal, which gives you 2nd harmonic tube-like distortion. This distortion
normally does not occur - but is sometimes desirable, being the reason for this special feature.
Unity circuit
The unity circuit feeds a low distortion unity gain signal to the JENSEN output transformer.
This gives the best possible sound quality.
Ground-lift“-Switch
This front panel mounted switch allows complete ground and electrical isolation between the
direct injection box and the console or recording device.
 

Mechanical Specifications
Cabinet 2 mm stainless steel
Front- and rear-panel 1,5 mm stainless steel lasercut and photo-chemically etched
Dimensions 185 x 100 x 40 mm
Vibration insulation 4 high-compliance rubber-elements
Operating Voltage
220/110 V AC, selectable via rear panel mounted switch. The fuse is easily
accessible from the rear panel. IEC mains connector with optional fixture.
Construction details
Double sided glass fibre contacted PCB with 70 mm copper plating. 1% metal film resistors
and the finest polypropylene capacitors are used in the signal path. MIL type Switchcraft jacks
and high performance switches ensure flawless operation. The power supply is optimised via
measurement quality toroid transformer and a low impedance design to ensure the lowest
possible noise. Through a double sided PCB all parts are roadworthy secured. A waterclear
blue LED perfects the aesthetics of the DI box.

Technical Data
Input impedance > 20 MOhm
Output impedance180 Ohm at 1 kHz
Frequncy response 20 Hz - 20 kHz (-0,1 dB)
                             5 Hz - 120 kHz (-3 dB)
THD at 0 dBv  0,06% at 20 Hz
                      0,04% at 1 kHz
                      0,035% at 20 kHz
Signal to Noise Ratio 86 dB
Tube ECC 83/7025 A - military E 83 CC optional
Output transformer JENSEN JT-DB-E
Polarity Pin 2 Hot , AES/IEC -Standard
Max. Input voltage > 30 V peak