Project · Direct To Console
Direct Box - Active
This is a simple active Direct Inject Box with some very nice features. It is similar to the active box featured in the Boscorelli Book The Stompbox Cookbook. The active circuit provides for some gain (volume) control on the output to the XLR jack. The circuit has a charge pump in order to provide more headroom for the input signal. It features a gain control, polarity switch and ground lift switch. If built in a metal enclosure (recommended) you should use a XLR jack with a plastic casing so that the ground lift to work properly.
Project files
Everything you need to build it
Active Direct Box Ready-For-Transfer Printed Circuit Board Layout
What you will need
Bill of Materials
Version 2019June30 · Copyright 2019 JD Sleep · Permission refused for posting/serving this file from any site other than www.generalguitargadgets.com · Trademarks are property of their owners
Resistors
| Resistor ID | Value | 3-band Marking | 4-band Marking |
|---|---|---|---|
| R1 | 150k | brown-green-yellow | brown-green-black-orange |
| R2 | 1k | brown-black-red | brown-black-black-brown |
| R3 (potentiometer) | 10k Log | ||
| R4 | 22k | red-red-orange | red-red-black-red |
| R5 | 22k | red-red-orange | red-red-black-red |
| R6 | 51 ohm | green-brown-black | green-brown-black-gold |
| R7 | 51 ohm | green-brown-black | green-brown-black-gold |
| R8 | 100k | brown-black-yellow | brown-black-black-orange |
| R9 | 100k | brown-black-yellow | brown-black-black-orange |
Capacitors
| Capacitor ID | Value | Type | Possible Marking |
|---|---|---|---|
| C1 (C1a and C1b are | 10µF | Tantalum or Aluminum | 10µF N.P. |
| alternatives to C1) | Electrolytic Non-Polar | ||
| C1a | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C1b | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C2 | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C3 | 100pF | Ceramic | 100pF |
| C4 | 100pF | Ceramic | 100pF |
| C5 (C5a and C5b are | 10µF | Tantalum or Aluminum | 10µF N.P. |
| alternatives to C5) | Electrolytic Non-Polar | ||
| C5a | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C5b | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C6 (C6a and C6b are | 10µF | Tantalum or Aluminum | 10µF N.P. |
| alternatives to C6) | Electrolytic Non-Polar | ||
| C6a | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C6b | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C7 | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
| C8 | 10µF | Tantalum or Aluminum Electrolytic | 10µF |
Potentiometers
| Part ID | Value | Type |
|---|---|---|
| R7 - Gain | 10k | Log (Audio) Taper Potentiometer |
Other
| Part ID | Part Name |
|---|---|
| IC1 | MAX1044 Charge Pump |
| IC2 | LM833 Opamp |
| Q1 | 2n3906 |
| Sw1 | DPDT on-on Toggle Switch |
| Sw2 | SPST Toggle Switch |
| J1 | Stereo quarter-inch jack |
| J2 | Male XLR Jack (plastic casing) |
| J3 | DC Jack |
| B1 | 9 volt battery (not included in the Kit) 9v battery snap, Printed Circuit Board 24 gauge stranded wire, Enclosure, Knobs |
How to build it
Instructions
Version 2016November17 · Copyright 2016 JD Sleep · Permission refused for posting/serving this file from any site other than www.generalguitargadgets.com · Trademarks are property of their owners
This is an active direct box for sending your guitar sound out to a balanced (XLR) output. There are some good useful controls on this box. Modeled after a Boscorelli design, this box has a Gain control, Ground Lift and polarity reverse switch. It runs on a 9v power supply, but the circuit includes a charge pump to deliver plus and minus 9 volts for more headroom. It fits in a 125B enclosure, with the XLR Jack on one end and the input on the other. There is also a “Thru jack so that you can continue on with your signal to the amp, etc. We added an LED light that shows if the unit is powered on. Here's a photo of the inside of the Active Direct Box:
More about this project
Notes, sounds and related links
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