Grace Design MOXi 2 Channel Instrument Preamplifier / EQ / DI

1 Welcome

This manual is intended for musicians and audio professionals. The MOXi is designed to be a reliable companion for enhancing your sound.

Please read this manual to familiarize yourself with the MOXi's features and setup options for optimal performance.

2 Safety And Symbols

Caution: Read Accompanying Documents. This symbol indicates important instructions. Read this manual thoroughly before operating the equipment.

Service Information

The Grace Design MOXi contains no user-serviceable components. Contact Grace Design for repair and upgrade information. For factory returns, contact Grace Design for a return authorization number.

3 Features

• Open, musical, and detailed instrument preamplification.
• 2-channel audio path with MIX or A/B output options.
• Mono FX loop with individual send and return.
• Ultra-precision 0.5% thin film resistors in the signal path.
• Careful power supply design and grounding for professional headroom and line driving ability.
• Ground-isolated DI output with high-quality, low-distortion, fully shielded transformer.
• Super rugged 1/4" connectors with heavy-duty metal bushings.
• Powerful, independent EQ on both channels (hi and low shelving, sweepable midrange).
• Switchable 75Hz HPF on both channels.
• A/B footswitch for multiple instrument configurations or soloing different pickups.
• Mute/tune footswitch mutes all outputs except FX send.
• Boost footswitch for variable 10dB level boost.
• Rear panel switch for Boost defeat on ch1.
• Dedicated line-level stage amp output.
• 6V mic bias power available on both 1/4" inputs.
• Phase reverse switch for each channel.
• Fixed 1MEG Ohm input impedance on both channels.
• 9VDC, 150mA power input (2.1mm center negative).
• Included power supply: external wall plug universal AC input, low noise 9V, 500mA, negative tip output.
• Full 5-year transferable warranty.
• Designed and built in Lyons, CO, USA.

4 Top Panel Features

The top panel features controls for:

1. Signal / clip LED indicator (ch1&2).
2. Gain controls.
3. 75Hz High Pass Filter toggle.
4. Low frequency shelving cut and boost.
5. Parametric Midrange cut and boost.
6. Parametric Midrange frequency select.
7. High frequency shelving cut and boost.
8. Boost level knob.
9. Power indicator LED.
10. Mix control (blends ch1 and ch2).
11. MUTE footswitch.
12. BOOST footswitch.
13. A/B footswitch.

5 Rear Panel Features

The rear panel features connections and switches:

1. Power input (9VDC, 150mA, 2.1mm negative tip).
2. DI Ground lift switch.
3. DI / ISO output (XLR).
4. Amp output (1/4").
5. FX loop send and return (1/4").
6. DIP switch bank.
7. ch2 Phase Reverse Switch.
8. ch2 1/4" Instrument Input.
9. ch1 Phase Reverse Switch.
10. ch1 1/4" Instrument Input.

6 Connections

6.1 1/4" Instrument Inputs, CH1 & CH2

These inputs accept instrument pickups, electret mics, or line sources. Both inputs have a 1MEG Ohm impedance. CH2 can accommodate signals from a dual-source pickup system using a single TRS 1/4" cable (tip=ch2, ring=ch1, sleeve=ground).

6.2 Insert Send and Return (FX Loop)

This provides a buffered, unbalanced insert point for connecting outboard effects or a tuner. The send features a -6dB pad option via internal jumper #10 for pedals that may be overdriven.

6.3 Amp Out

This unbalanced, non-transformer isolated output is for sending a signal to a stage amp or other devices. It can be set to not mute via internal jumper #8.

6.4 DI Output

This is a balanced, transformer-isolated XLR output for sending your signal to a PA, monitor console, or mixer. The output level is -18dB by default, adjustable to -6dB via internal jumper #11.

6.5 9VDC Power Input

This is a standard 2.1mm barrel jack with a center-negative. Requires a power supply capable of delivering at least 200mA.

7 Operation

7.1 Where to Put Your Preamp?

The MOXi is built for stage use with a durable chassis. Rubber feet can be removed for pedalboard mounting with Velcro®.

7.2 Instrument/Line Inputs

The MOXi is designed to work with various instrument pickup types. The CH2 input can be used with a single TRS cable for dual-source pickup systems, allowing separate EQ and blending of each source.

6V Power: The instrument inputs can provide 6V mic bias power for electret capacitor microphones. This is activated via DIP switches #3 and #4 on the rear panel. Note that activating the 6V circuit can alter the sound of passive pickups.

7.3 Filtering and EQ

The MOXi features identical, independent EQ controls for each channel. The EQ includes:

• HPF: A switchable 75Hz High Pass Filter with a 12dB/octave roll-off.
• Low: A 250Hz shelving control with a gain range of -12 to +12dB.
• Mid: A sweepable bell filter with a gain range of +/-12dB and a frequency range of 125Hz – 4kHz (fixed Q factor of 2).
• High: A 1.5kHz shelving control with a gain range of -12 to +12dB.

7.4 Output Controls and Settings

• Boost: Controlled by the BOOST footswitch, with a level adjustable from 0 to +10dB via the boost knob. Boost can be defeated on CH1 via DIP switch #2.
• Mix: Adjusts the mix (blend) between CH1 and CH2. When set to MIX mode (DIP switch #1 down), this control acts as a blend knob (fully counter-clockwise is 100% CH1, fully clockwise is 100% CH2, 12 o'clock is 50/50).

7.5 Footswitch Controls

• Blend - A/B: When in MIX mode, this switch has no function. When in A/B mode, this switch toggles between CH1 and CH2.
• Boost: Activates the boost circuit. The LED lights green when active.
• Mute/Tune: Mutes all outputs except the FX send. The LED lights red when active.

7.6 Rear Panel Controls

• Phase Reverse: Pushbutton switches to reverse the polarity of each channel's audio signal.
• DIP Switches: A bank of 4 switches for various settings:
  • Switch 1: Selects between MIX and A/B mode.
  • Switch 2: Deactivates the boost circuit on CH1.
  • Switches 3 & 4: Activate 6V mic bias power for instrument inputs.

8 Internal Jumpers

The MOXi has three internal jumpers for advanced setup options:

• Jumper J8: A -6dB pad for the insert send to prevent overloading FX pedals. Factory setting: 0dB (middle and top pins). For -6dB pad, move jumper to middle and bottom pins.
• Jumper J10: Controls whether the AMP OUT jack mutes when the mute switch is engaged. Factory setting: Mute enabled (center and left pins). To disable mute, move jumper to center and right pins.
• Jumper J11: Adjusts the DI output level. Factory setting: -18dB (center and left pins). For -6dB output level, move jumper to center and right pins.

Adjusting Internal Jumpers: Disconnect power and instrument cables. Remove the 4 chassis screws on the top chassis. Carefully lift and flip the top chassis to access the circuit boards. Use tweezers or fingers to move jumpers. Ensure no loose jumpers remain inside. Reassemble carefully, ensuring ribbon cable is not strained.

9 Connection Diagram

Illustrates how to connect instruments, effects, amplifiers, and PA systems to the MOXi.

Connections:

• 9VDC Power: From the included wall wart or a regulated 200mA DC output.
• DI Out: Connects to PA/mixer or recording interface.
• Amp Out: Connects to stage amp, powered speaker, etc.
• FX Send: Connects to FX pedal input.
• FX Return: Connects to FX pedal output.
• Instrument Inputs (CH1 & CH2): For acoustic or electric instruments with pickups or internal mics.

10 Block Diagram

Provides a visual representation of the MOXi's internal signal flow and component connections.

11 Specifications

12 Cleaning and Maintenance

The MOXi chassis is constructed of high-quality aluminum and steel. For cleaning, use a clean, dry, lint-free cloth lightly sprayed with Windex™. Avoid allowing cleaning product to build up around or under the knobs.

13 Warranty

Grace Design warrants this product to be free of defective parts and workmanship for five years from the original date of purchase. This warranty is transferable.

Exclusions: Normal wear and tear, misuse, customer negligence, accidental damage, unauthorized repair or modification, cosmetic damage, and damage incurred during shipment.

Grace Design will repair or replace defective parts or workmanship at no charge during the warranty period, provided the customer has proof of purchase and the original factory serial number.

Product Registration: Register your product within 10 days of purchase via telephone (303-823-8100) or online at www.gracedesign.com for efficient warranty service.

This warranty is in lieu of all other warranties, expressed or implied, including warranties of merchantability or fitness for a particular purpose. Grace Design's liability shall not exceed the purchase price of the product.

This warranty grants specific legal rights, and customers may have other rights that vary by state.

14 Manual Revisions