GRACE DESIGN EQ Microphone and Instrument Preamplifier Owner’s Manual

: June 10, 2024
: GRACE DESIGN

EQ Microphone and Instrument Preamplifier

GRACE DESIGN EQ Microphone and Instrument Preamplifier Owner's Manual-
product

Product Information

ROXi Microphone and Instrument Preamplifier / EQ / DI

The ROXi is a microphone and instrument preamplifier, EQ, and DI designed and manufactured by Grace Design. It is a compact footpedal that is built to be rugged and reliable for use on stage. The ROXi is designed to provide high- quality sound for any source that is plugged into it, and it is capable of competing with full-size studio gear.

Features

Mic preamp and EQ
Phase Reverse
12V Power
Boost control
Boost Trim Function
FX Dry / Wet Control
AMP level control
Filtering and EQ
Output controls
Footswitch Controls
Side Panel Controls
FX SEND and RETURN
Amp Out
Tuner Output
DI Output
100-240VAC Power Input
9V @ 500mA DC POWER OUTPUT

Product Usage Instructions

Step 1: Connect the ROXi to a power source using the 100-240VAC Power Input or the 9V @ 500mA DC POWER OUTPUT.

Step 2: Connect a microphone or instrument to the input jack on the top panel of the ROXi.

Step 3: Adjust the gain using the Setting the Gain control on the top panel.

Step 4: Use the Boost control and Boost Trim Function to adjust the level of the input signal.

Step 5: Use the Filtering and EQ controls to adjust the tone of the input signal.

Step 6: Use the Output controls to adjust the level of the output signal.

Step 7: Use the FX SEND and RETURN, Amp Out, Tuner Output, or DI Output as needed for your setup.

Step 8: Use the Footswitch Controls and Side Panel Controls to access additional features and functions as needed.

Note: For more detailed information on using the ROXi, please refer to the Owner’s Manual Rev. A provided by Grace Design.

Welcome

Welcome and thank you purchasing this ROXi microphone preamp pedal. This little box is the culmination of many decades of us refining our mic and instrument preamps, and then packing it all into a single, rugged stage box. Even though it’s a compact footpedal, we cut no corners designing and building this unit. As a mic preamp and EQ, it will compete with any full size studio gear and help any source you plug into it sound incredible. Our hope is that the ROXi encourages you to be wildly creative and play your very best. While it’s a fairly simple bit of hardware, there are some subtle and cool features that are best understood by reading this manual. Enjoy!
Have fun!

The Grace Design Team

Safety Information

Indoor use only
Ordinary Protection: This equipment should not be exposed to dripping or splashing.
Avoid placing objects filled with liquids, such as vases or glasses, on this equipment.
Class I Equipment (grounded type)
Electrical rating: 100-240V~ 50-60Hz 10W
Mains supply voltage fluctuations are not to exceed ±10%of the nominal supply voltage.
Pollution Degree 2
Installation (Over voltage) Category II for transient overvoltages.
Maximum Relative Humidity: <80%
Operation temperature range: 10 °C to 40 °C
Storage and transportation temperature range –40 °C to 70 °C
Maximum altitude: 3000m (9843 ft)
Equipment suitable for continuous operation
Weight: 2.2lbs

Features

Studio-quality mic preamplifier
Precision gold-contact rotary gain control switch
48V phantom power
Ultra precision 0.5% thin film resistors used in the signal path
Careful power supply design and grounding for an ultra-quiet signal path and professional level headroom and line driving ability
Fully ground-isolated DI output with high-quality, low-distortion, fully shielded transformer
Rugged 1/4” connectors with heavy duty metal bushings
Powerful, independent EQ – HIGH and LOW shelving and sweepable midrange
Switchable 75Hz or 150Hz High Pass Filter
Mute/ tune footswitch mutes all outputs except dedicated tuner out and headphone output
12V mic input power
9VDC @ 500mA (2.1mm BOSS™ standard center negative) power output for powering other pedals from the ROXi
Boost footswitch for variable 10dB level boost
Dedicated level controlled stage amp output
Dedicated tuner out, remains active when unit is muted
Side panel DIP switches various settings and controls
FX insert loop with an optional footswitch function for FX insert mute
FX Insert Mix control
Universal 100-240 AC power supply with standard IEC cable – no wall wart – take ROXi anywhere in the world!
Full 5 year transferable warranty / built for a long, happy life on the road
Designed and built by us in Lyons, CO, USA

Top Panel Controls and Features

Gain control
Signal / peak LED indicator
Boost level
FX insert blend control
Amp / Tuner output level
Power indicator light
BOOST / FX footswitch
Low frequency shelving cut and boost
Midrange cut and boost
Midrange frequency select
MUTE / TUNE footswitch
High frequency shelving cut and boost

Back Panel Controls and Features

Universal 100-240VAC power supply input
DI output ground lift switch
Balanced XLR DI output
Balanced ¼” amp output
Stage Tuner ¼” output
Effects insert return
Effects insert send
XLR / 1/4″ combo input jack
48V phantom power switch
Phase reverse switch

Side Panel Controls and Features

DIP Switch function diagram
9VDC, 500mA output
DIP switch controls:
DI output level switch
High Pass Filter roll off select
High Pass Filter on/off
12V electret mic power on/off
9V output on/off
Footswitch 2 function, boost or insert

Connecting ROXi to Stuff

XLR MIC / ¼” LINE COMBO INPUT
This input can accommodate any type of microphone – dynamic, condenser or ribbon – via the XLR input, or any ¼” mono instrument input via the center ¼” phono jack. The XLR connector is wired pin 2 positive, pin 3 negative and pin 1 ground. The ¼” center of the combo jack is for connecting any instrument with a pickup, electret mic or line out jack to the ROXi. The jack is a standard 1/4” wired tip signal, sleeve ground. The ring is used only for 12V mic power if needed.

FX SEND AND RETURN
These send and return jacks create a buffered, unbalanced insert point (pre- boost) for connecting outboard effects to ROXi. This allows mono outboard signal processing to be placed in series with the signal, while still utilizing all of ROXi’s output capabilities. The insert send has an adjustable pad if you are using an effect pedal with lower headroom. The pad has 3 settings (off, -6dB and -16dB) that can be set via internal jumpers.
SEE JUMPER DIAGRAM page 12

AMP OUT
This output is for sending a balanced or unbalanced, non-transformer isolated output to a stage amp or anywhere else you may need an additional signal. This output has the added benefit of a level

TUNER OUTPUT
This is another unbalanced output which is always active – provided as a dedicated stage tuner out. When the MUTE is activated, your stage tuner will continue to receive signal, allowing you to tune silently. The tuner output level follows the Amp Out level control. NOTE: because the tuner output level follows the AMP level control, if your AMP level control is turned down, your tuner won’t work.

DI OUTPUT
This output is balanced and transformer isolated, for sending signal to a front of house, monitor console, or any mixer or interface where balanced, isolated signal needs to be sent. XLR pin-out is: pin 2 positive, pin 3 negative and pin 1 ground. This output has a level setting switch – side panel DIP switch #1, labeled line and mic. In the ‘mic’ setting, the output is padded down -26dB to interface properly with mic inputs at the console, while the ‘line’ setting is not padded for better level matching with line level inputs at the console or interface.

100-240VAC POWER INPUT
ROXi is powered by a universal AC power supply. This means that no matter where your musical wanderings take you, ROXi can plug into the wall and it will work. And it also means one less wall wart you’ll own in your life. All units are shipped with a standard AC cable suitable for the country where it is going. This is a standard, off-the-shelf IEC power cable, so in the event you misplace the one that came with your ROXi, you can just borrow one from a bandmate and go. Tell them we said so.

9V @ 500mA DC POWER OUTPUT
This output jack will power other 9VDC pedals you may have at your feet. The jack is a standard 2.1mm BOSS™ style, with the center negative. Maximum output current is 500mA, which means you need to add up the current draw of all the pedals you wish to power to ensure they don’t exceed that. To connect multiple pedals, you’ll need an off the shelf multi-plug daisy chain cable.

Operation

WHERE TO PUT ROXI?
Great question. We recommend you put it wherever you want. It will look very pretty when you first pull it out of its box, but trust us, it’s built to stand up to just about any kind of stage shenanigans you might encounter. All the pots have metal shafts and are well mounted to the top panel. All the 1/4” jacks have heavy duty metal bushings. The top panel is 1/4” extruded aluminum, and the bottom chassis is heavy-duty aluminum.
As you probably know, the main inspiration for this product was to provide studio-grade audio hardware, properly ruggedized to work on stage or mounted to a pedal board. Velcro is fine. The installed rubber feet will thread out so your Velcro mount will be flush. Hang on to those rubber feet, though, they’re pretty nice.

MICROPHONE / LINE INPUT
To connect a microphone to ROXi, first make sure the top panel gain knob is turned all the way down and the adjacent red 48V phantom power switch is set to off (pushed out). Then connect your microphone and if 48V is needed, simply activate it with the 48V switch. Always remember to turn 48V power on after connecting your microphone and off before disconnecting your microphone.
To connect an instrument, simply plug a 1/4″ instrument cable into the center of the combo jack.

SETTING THE GAIN
The first knob on the left side of the top panel is the GAIN control. With your mic or instrument connected to the input and signal flowing, turn the GAIN knob clockwise until the signal / clip LED indicator is on and lit solid green. This will represent a good operating level. The indicator will start to flash red when your signal is 13dB before clipping, so occasional red flash is ok, but all red means you should turn the gain control down. Gain range for this input is adjustable between +5dB to +60dB (mic) or -15dB to +40dB (instrument). The Boost control can add another 10dB to these ranges. Also, the 1/4″ instrument input has a jumper (J4) to select between a LOW and HIGH gain setting, the HIGH gain setting offering a gain range of 0dB to +55dB.

PHASE REVERSE
ROXi has a phase reverse switch, located on the rear panel, top right (facing the rearpanel). Use this to toggle the polarity of audio signal. Phase relationships can be very complicated, and discrepancies can result in accentuated or de-accentuated bass response of an out of phase signal. It can sound hollowed out and thin, or just downright weird. The rule of thumb here is whatever sounds right is probably right. There may be setup scenarios where the front of house or monitor engineer requires you to try flipping the phase to achieve better phase coherency with other signals in the mix. At the very least, it’s good for you to know how to operate this controls and hear it in use with your instrument.

12V POWER
The ¼” instrument input of the combo jack can be used to amplify an electret capacitor microphone. These are common for applications where a small microphone is mounted inside acoustic instruments, or a clip-on lavalier style microphone used somewhere on the outside of the instrument. Normally these microphones will contain very small integrated preamps which require a voltage to power. So the ROXi can send 12V power out on this input. This is activated via DIP switch #5 on the side panel. 12V power can be applied to the tip or ring of the instrument input combo jack. Configuration is done via internal jumpers, described in detail in the following “Internal Jumpers” chapter. When switched on, this power supply charges up slowly, so you may need to wait a few seconds before signal from your electret mic is present at the input of ROXi. It is always best to make your input connections before applying power at the DIP switch, and power OFF the 12V at the DIP switch before disconnecting your source.

NOTE: the 12V power is supplied through a current limiting resistor that allows the power supply to be used with mics rated for as low as 3V. This includes DPA 4000 series mics and the K&K Trinity mic.

BOOST CONTROL
Want ROXi to go to almost eleven? This knob sets the amount your signal is boosted when you activate the ‘BOOST’ footswitch. Fully counter-clockwise is zero boost added, fully clockwise adds +10dB of boost. As you can probably imagine, if you are using a microphone or a particularly feedback prone pickup system, adding boost might easily send you in to feedback territory. So start small. If you need to boost your output, start with a gentle boost amount and work your way upwards. If you start to hear stage feedback or are overloading the input at the console, then you’ll need to back it off. We are not responsible for disgruntled soundpeople you may encounter during the operation of the boost circuit.

BOOST TRIM FUNCTION
The Boost footswitch (FS2) has an alternate function that activates or deactivates the FX insert. This function is selected via the sidepanel DIP switch #6, labeled FS2. If you are using this mode, we have included a bonus feature that allows you to permanently engage the Boost circuit and use the Boost knob as an additional gain trim control. This gives you to access the additional 10dB of gain provided by the boost circuit. This gain / trim setting will remain on regardless of DIP switch #6 setting. This Boost Trim function is activated by setting internal jumper J2 to the ‘on’ position. The instructions for this jumper procedure is illustrated on pages 11 & 12.

FX DRY / WET CONTROL
This knob allows you to vary the amount of effected signal vs. dry signal in the FX loop. If your effects are too prominent in your output, simply turn the knob counter-clockwise, or turn the knob clockwise to increase the amount of effects in your signal. You might experiment running your individual effects wetter than normal, then use the control to tailor them according the particular stage or room where you are performing.

AMP LEVEL CONTROL
This allows you to adjust the level of the signal being sent on the AMP out jack on the rearpanel. 12 o’clock is unity gain which matches the output level of the DI out (when set to line level). REMEMBER, this also effects the level of the TUNER out, so if your tuner isn’t getting signal, double check you that you have this control turned up sufficiently.

FILTERING AND EQ
One of the defining features of ROXi is the very powerful, EQ / filter controls. If you haven’t used EQ’s or filters much, we will provide a basic overview here. But the full science of this process is more than we can cover here, so we strongly recommend some adjunct reading:
http://en.wikipedia.org/wiki/Equalization As with all audio processing techniques, the more you know, the better you will sound.

HPF
The High Pass Filter (HPF) allows signal information only above its set frequency to pass to the output. You can also think of this as a low-cut. This filter employs 12dB per octave roll off and is designed to be very musical sounding. Use this control to tame unwanted low end rumble or stage noise that may find its way into your microphone. The HPF is activated with the side panel DIP switch #3 – the up position activates the HPF, the down position turns it off. There are 2 HPF roll off frequencies: 75Hz and 150Hz which are set by the side panel DIP switch #2.

LOW Control
The Low control is for adjusting the bass frequencies in your signal. The control fixed at 125Hz (+-3dB) corner frequency (40Hz peak), with a gain range of -10 to +10dB. This is a fixed shelving type control, which means everything below the 125Hz is boosted or cut. It’s all about the bass.

Also, because certain acoustic instruments (banjo, fiddle, plinkly little whathaveyous) may react better to a higher corner frequency, we have added a Low control range jumper on the main PCB. Moving this jumper shifts the Low frequency up to 250Hz (+/-3dB) corner frequency. This is easy to do! We specifically designed ROXi’s chassis to make it easy to access internal jumpers. Please refer to the jumper diagram and access procedure on pages 11 and 12.

WARNING Make sure to disconnect the power mains before opening removing the ROXi top panel to make jumper adjustments.

MID Controls
The mid range section of ROXi’s equalizer is semi-parametric, which enables you control the mid range gain and frequency at a fixed Q factor. The range of these controls are:
Gain = +/- 10dB,
Freq Hz setting = 175Hz – 4kHz
Fixed Q factor = 1.2

In general, you use the mid range EQ control to affect frequencies in the typical range of the human voice or most instruments. Turning it down results in a more ‘scooped’ sound, turning up a honkier or peaky sound. Heres a good read on frequencies: https://en.wikipedia.org/wiki/Audio_frequency

High Control
The High control of the ROXi preamplifier is set with a 2kHz (+/-3dB) corner frequency (12kHz peak), with a gain range of -10 to +10dB. This is a fixed shelving type control, which means everything above the 2kHz is boosted or cut. Simply put, this is a treble control. If you think your banjo may be too bright, turn this knob counterclockwise. If you think your guitar needs a little more bite, turn this knob clockwise. If you’re not sure, then get down there and start turning it one way or the other until it sounds better.

And the same as the Low control, we have added a High control range jumper on the main PCB. Moving this jumper shifts the High frequency down to a 1kHz corner frequency. Please refer to the jumper diagram and access procedure on pages 11 and 12.

OUTPUT CONTROLS

Boost
This knob sets the amount your signal is boosted when you activate the ‘BOOST’ footswitch. Fully counter-clockwise is zero boost added, fully clockwise adds +10dB of boost. The boost is after the FX loop and affects both the DI and amp outputs. As you can probably imagine, if you are using a microphone or a feedback prone pickup system, adding boost will send you in to feedback territory. So start small. If you need to boost your output, start with a gentle boost amount and work your way upwards. If you start to hear stage feedback or are overloading the input at the console, then you’ll need to back it off. ROXi is not responsible for disgruntled soundpeople you may encounter during the operation of the boost circuit, especially those you have already borrowed your misplaced IEC power cable from. Keep those people happy, they control the suck knob.

Amp Output Level
This knob sets the output level of the amp and tuner outputs on the rearpanel. If you are using a stage amp, use this control as your master level. Correct input gain settings for your sources, with the signal LED showing mostly green, should not be adjusted to alter your stage amp level. Rather, use this control to make master level changes. Troubleshooting advice: if your stage tuner is connected to the ‘tuner’ jack but not working, make sure your Amp out knob is turned up sufficiently.

FOOTSWITCH CONTROLS

Boost / FX
This switch has two different functions based on the setting of DIP switch #6 labeled FS2. In the Boost setting (switch in the down position), the footswitch enables the boost circuit. When active, the LED will be lit and the output signal is boosted by the amount set by the ‘BOOST’ knob. More is always better, but feedback and angry soundpeople can make for an uncomfortable gig, so start small! In FX setting, (switch in up position) the footswitch activates or deactivates the insert / FX loop. There are 2 different modes for operating the FX footswitch:

• Mutes the return of the FX loop, so whatever signal is still in the FX loop (i.e. reverb or delay tails) will be cut immediately.
• Mutes at the send of the FX loop, allowing signals (i.e. reverb or delay tails) in the FX loop to trail off naturally.

These two options are selected via the internal Jumper J10.
Also, remember, if you are using the Boost footswitch for FX insert control, you can also turn on the ‘Boost Trim Function’ via internal jumper J2, which allows you to use the Boost control knob as an addition 10dB gain / trim control.

Mute / Tune
This switch mutes the DI and AMP output, but not the tuner output. This enables you to quickly and easily cut your signal to the FOH or stage amp and tune or unplug your instrument without having to have the soundperson mute your channel. When MUTE / tune is active, the adjacent LED illuminates RED.

SIDE PANEL CONTROLS

ROXi has a lot going on, more than we could fit on the rear and top panels alone. So there are a few features to be familiar with on the side panel.

DIP Switches
This is a bank of 6 DIP switches, used to activate these various modes and settings.

DI output level switch (MIC and LINE)
High Pass Filter roll off select (75Hz or 125Hz)
High Pass Filter on/off
12 Volt phantom power on/off
9V output on/off
Footswitch 2 function, boost or insert

DIP switches are a little hard to move, which is good because they probably won’t get inadvertently changed, but bad when you actually want to use them. Use the edge of a fingernail, a guitar pic or a toothpick. Whatever you chose, take care not to dig into the plastic too hard. You’ll get the hang of it.

Diagrams

BLOCK DIAGRAM

CONNECTION DIAGRAM

ADJUSTING INTERNAL JUMPERS
Several ROXi settings can be adjusted via internal jumpers. While it’s not trivial to do, if you are handy with a screwdriver and tweezers, you’ll be fine. This is not something you should attempt to do on a dark stage or in the back of the tour van.
Directions for disassembling the chassis and accessing the jumpers is as follows:

IMPORTANT: Before you do anything, disconnect ROXi from the AC power, disconnect all cables and place ROXi on a flat stable surface with good lighting.

DOUBLE CHECK: Did you completely disconnect the power supply? Ok then.
With a #2 Phillips screwdriver, remove the 4 chassis screws, located on the outer edges of the front bottom and rear bottom of the aluminum top chassis (figure 1) .
Orient the unit so the rearpanel is facing forward towards you. Carefully pull up on the top chassis and flip it up
and over the bottom chassis (figure 2). This will reveal the top and bottom circuit boards. Do not pull them apart any further than the ribbon cables that connect them will allow. The top should rest easily on the work surface flipped over and behind the bottom chassis (figure 3).
Now refer to the jumper location diagram on the following page to move any jumpers you wish (closeup – figure 4).
To move a jumper, use tweezers or your fingernails to gently pull the jumper off of its header pins. To reposition the jumper, double check the diagram, then gently press the jumper back down in the correct location.
When you are finished adjusting the jumpers, make sure there are no loose jumpers or any other junk lying around inside your ROXi.
Then carefully reassemble the top and bottom chassis, making sure to let the ribbon cable fold easily back in place. If there is any tension or something isn’t fitting properly, carefully pull the top and bottom back apart and inspect for interference.
Once you have put the unit back together, replace the 4 screws, making sure they go in straight and true. You may need to nudge the top panel back and forth a bit to ensure the holes in the top panel chassis line up evenly with the inner threaded holes.
Do not tighten the screws until all 4 are cleanly started in the threads. Take your time and remember, cross-threading is a crime.

INTERNAL JUMPER LOCATIONS

Specifications

GRACE DESIGN EQ Microphone and Instrument Preamplifier
Owner's Manual-fig-13

Cleaning and Maintenance

Your ROXi is chassis is constructed out of high quality aluminum and steel. Under normal circumstances, very little maintenance is required to keep it looking good. However, if you find it getting more dirty or dusty than you like, here are some cleaning tips: We recommend using a little shot of Windex™, applied to a clean, dry, lint free cloth. Gently wipe all surfaces, taking care not to allow the cleaning product to build up around or under the knobs.

Warranty

Grace Design warrants this product to be free of defective parts and workmanship for a period of five years. This warranty period begins at the original date of purchase and is transferable to any person who may subsequently purchase the product during this time.
This warranty excludes the following conditions: normal wear and tear, misuse, customer negligence, accidental damage, unauthorized repair or modification, cosmetic damage and damage incurred during shipment.
During the time of this warranty, Grace Design will repair or replace, at its option, any defective parts or repair defective workmanship without charge, provided the customer has appropriate proof of purchase and that the product has its original factory serial number.
In order for Grace Design to provide efficient and timely warranty service, it is important that you mail the completed warranty registration card enclosed with all of our products within 10 days of the original date of purchase. You may also register your product directly with Grace Design by telephone (303-823-8100 Monday-Friday 9:00am to 5:00pm MST), or you can register your product online at www.gracedesign.com.
This warranty is in lieu of all other warranties whether written, expressed, or implied, INCLUDING ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
In no event will Grace Design be liable for lost profits or any other incidental, consequential or Exemplary damages, even if Grace Design is aware of the possibility of such damages. In no event will Grace Design’s liability exceed the purchase price of the product.
This warranty gives the customer specific legal rights. The customer may also have other rights, which vary from state to state. Some states do not allow limitations on implied warranties or consequential damages, so some of the limitations of the above may not apply to a particular customer.