The DI503J is a triple mode Direct Box for instrument and a Re-Amp unit for the '500' format of API*.

The DI offers a passive mode based on the premium Jensen JT-DB-EPC transformer, a FET mode of very high impedance and a tube mode for a warmer sound. It also include a low noise, low distortion preamp for a line level output.

The Re-Amp uses a high quality shielded transformer from Carnhill/OEP.

Highlights

• 3 modes DI: FET / Passive / Tube,
• Premium Jensen transformer in the 3 modes,
• Very large headroom in all 3 modes,
• Low noise low distortion optional preamp for line level output,
• Shielded Carnhill/OEP transformer on Re-Amp,
• High grade components throughout,
• Available assembled or as a full kit (everything included).

1.a: PASSIVE mode: The instrument signal is routed through a premium quality Jensen transformer, the JT-DB-EPC which lowers the impedance allowing long wires to the preamp. The input impedance seen by the instrument is around 300 kilo-ohms.

1.b: FET mode: The instrument signal is buffered by a very high impedance FET stage before going to the Jensen transformer. The input impedance seen by the instrument is around 3.2 megohms.

1.c: TUBE mode: The instrument signal is buffered by a tube stage before going to the Jensen transformer. The input impedance seen by the instrument is around 1.5 megohms. The tube feedback can be modified by the DIST switch.

2: DIST: Removes the feedback on the tube which increases the warmth and character of the sound with second order distortion. The added distortion depends directly on the instrument level. When activated, a passive filter is added which acts as a basic cab simulator.

3: POL: Reverses the polarity of the instrument signal. Useful when the DI signal is combined with a miked signal.

4-5: PREAMP: The ON switch activates an inbuilt, ultra low noise, low distortion, preamplifier after the Jensen transformer, eliminating the need for an external preamp. The gain is set by the potentiometer from +8 to +60dB.

6: LIFT: This switch is a ground lift. It disconnects the instrument ground from the lunchbox ground which is useful in case of hum loops. It works for both the DI and the Re-Amp but is only available in the passive mode for the DI.

7-8: RE-AMP: The ON switch activates the Re-amp function. It disconnects the OUT jack from the INSTRUMENT jack and connects it to the Lunchbox input XLR via a line transformer and the LEVEL potentiometer.

9: OUT: It is a through connection for the instrument when the Re-Amp ON switch is off. It is the Re-Amp output when the Re-Amp ON switch is on.

10: INSTRUMENT: It is the input of the DI.

1: Live setup:

The DI XLR output goes to the PA system. It may go to a microphone input or to a line input depending on the PREAMP switch state.

The through OUT is used to connect to the player's amp.

The POL switch can be used if there is a phase issue between the PA and the amp.

The LIFT switch can be used if there is a hum loop issue.

2: Studio setup:

The DI XLR output goes to the DAW input converters. It may go through a preamp if some sound character is looked after.

The through OUT is used to connect to an amp which can be miked.

The POL switch can be used if there is a phase issue between the monitors and the amp.

3: Re-amp setup:

The Re-Amp XLR input goes to an output converter of the DAW.

The OUT is used to connect to the amp which is miked.

4: Effect loop at mixdown:

The Re-Amp XLR input goes to the DAW output converters.

The DI XLR output goes to the DAW input converters.

The effect device is connected between OUT and INSTRUMENT and is inserted as a track effect in the DAW.

5: Effect loop for instrument:

The Re-Amp XLR input goes to the DAW output converters.

The DI XLR output goes to the DAW input converters.

The computer is used to add digital effects to the instrument.

What's in the kit?

Absolutely everything!

• Passive components (resistors, capacitors),
• Jensen and Carnhill transformers
• Active components (Tube, diodes, transistors, ...),
• Front panel elements (switches, potentiometers, knobs),
• Connectors, relay,
• PCB's,
• Front panel and side panel,
• All hardware.

You bring the solder (use good quality solder, 1mm diameter max) and the Lunchbox.

Difficulty level

The DI503J kit is a medium difficulty build.