Grace Felix Owner's Manual

2 Channel Instrument Preamplifier / EQ / Blender

Owner’s Manual Rev. A

Grace Design, 4689 Ute Highway, Lyons, CO 80503

303.823.8100 / [e-mail]
www.gracedesign.com

1

1 Welcome

If you’re reading this, you are probably a working musician or
audio professional of some kind. You’ve spent years honing
your craft with long, lonely hours spent strumming, picking,
tweaking, bowing, thumping and plucking. Maybe you tour the
world, or just the local coeshops. You’ve gotten up on stage
tired, given more than you thought you had and driven home
barely awake but your soul still singing. You have friends and
bandmates out there that you rely on like family. Some of your
friends, maybe the very best ones, are made of wood, steel,
glue, bone and strings. And now you can welcome Felix to the
latter category.

Regardless of where you end up playing, from here on when

TABLE OF CONTENTS

1 Welcome 2

2 Safety Information 2

3 Safety Marking Symbols 3

4 Features 3

5 Top Panel Controls and Features 4

6 Back Panel Controls and Features 5

7 Side Panel Controls and Features 5

8 Connecting Felix to Stu 6

8.1 1/4” Instrument inputs, Ch1 and Ch2 6

8.2 Ch1 XLR mic input 6

8.3 Insert 6

8.4 Amp Out 6

8.5 Tuner Output 6

8.6 FS - footswitch Input 6

8.7 DI Outputs, Ch1 & Ch2 6

8.8 Headphone Output 6

8.9 100-240VAC Power Input 7

9 Operation 7

you look down at that stage oor, he’ll be down there shining
back up at you, making you sound better and your job easier.

While Felix is not the most complicated piece of gear you’ve
ever operated, he does come with a great deal of exibility and
setup options, which means we highly recommend you have
a good look at this owner’s manual to familiarize yourself with
his ner points. Once you overcome the learning curve (easy,
we promise), you’ll nd Felix to be intuitive, powerful and really
quite user friendly.

Most of all, we made Felix so you can make great music. So read
this manual and then get back to work!

9.1 Where to put Felix? 7

9.2 Using the XLR mic input Ch1 7

9.3 Instrument / line inputs 7

9.4 Filtering and EQ 8

9.5 Output controls 9

9.6 Footswitch Controls 10

9.7 Side Panel Controls 10

10 Diagrams 11

10.1 Insert cable Wiring 11

10.2 External Footswitch Wiring 11

10.3 Adjusting Internal Jumpers 12

10.4 Internal Jumper Locations 13

10.5 Block Diagram 14

10.6 Connection Diagram 15

11 Specications 16

12 Cleaning and Maintenance 17

13 Warranty 17

14 Manual Revisions 18

2 Safety Information

• Indoor use only

• Ordinary Protection: This equipment should not be
exposed to dripping or splashing.

• Avoid placing objects lled 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 uctuations are not to exceed ±10%
of the nominal supply voltage.

• Pollution Degree 2

• Installation (Over voltage) Category II for transient
overvoltages.

2

• 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: 3.2lbs

3 Safety Marking Symbols

Caution: Read Accompanying Documents

This symbol, located on the equipment and in
this manual, refers to important instructions.
Read this manual thoroughly before operating
this equipment.

Warning: Electrical Shock Hazard

This symbol, located on the equipment and in
this manual, indicates the potential for electrical
shock hazard.

4 Features

• Open, musical and detailed instrument and mic
preamplication for discerning artists and engineers like
yourself

• 2 channel audio path with mix output option

• m101 style transimpedance microphone preamplier, no
electrolytic capacitors in the signal path

• Ultra precision 0.5% thin lm resistors used in the signal
path

• Careful power supply design and grounding for an ultra­quiet signal path and professional level headroom and line
driving ability

• Dual, fully ground isolated DI outputs with high quality,
low distortion, fully shielded transformers

• Super rugged 1/4” connectors with heavy duty metal
bushings

• Powerful, independent EQ on both channels – hi and low
shelving and full parametric midrange

• Mid frequency control has two ranges 70-880Hz / 670 ­8kHz

Service Information

The Grace Design Felix contains no user serviceable
components. Contact Grace Design for repair and upgrade
information. In the event that your Grace Design m920
needs to be returned to the factory, contact us for a return
authorization number.

• 1/8” headphone jack, remains active when is muted

• Side panel switches for 48V, phase, mid Hz range select,
HPF/notch select, 12V and A/B mode select

• 12V mic input power available on Ch1 and Ch2 1/4” inputs

• Phase reverse switch for each channel

• 3 input impedance settings on each channel – Ch1 10K,
1MEG, 10MEG / Ch2 332K, 1MEG, 20MEG accommodating a
wide range of pickup types

• Aux footswitch jack for accessing switch functions if Felix is
mounted in a rack tray or on top of an amp

• Mic stand ange mount screw holes for mounting Felix on
a mic stand

• Global TRS eects insert jack

• Universal 100-240 AC power supply with standard IEC
cable – no wall wart - take Felix 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

• 20Hz-1kHz sweepable HPF on both channels, can also be
set as notch lter

• A / B footswitch for multiple instrument congurations or
soloing dierent pickups

• Mute/ tune footswitch mutes all outputs except dedicated
tuner out and headphone output

• Boost footswitch for variable 10dB level boost (global)

• DI outputs sources are congurable - Ch1 (mix or Ch1) Ch2
(mix or Ch2)

• Dedicated level controlled stage amp output (congurable
as MIX or Ch2)

• Dedicated tuner out, remains active when unit is muted

3

5 Top Panel Controls and Features

8

2.3k
250

1k

670 8k

70

2.3k
250

1k

670

70

6

3.6k

400

6.4k

HI

880

LO

3.6k

400

6.4k

8k

HI

880

LO

7

1 2 3 4 9

5

110 700

110 700

10

11 12

1. Gain controls (Ch1&2)

2. Signal / clip LED indicator (Ch1&2)

3. High Pass Filter (notch) / Notch lter (Ch1&2)

4. Low frequency shelving cut and boost (Ch1&2)

5. Parametric Midrange cut and boost (Ch1&2)

6. Parametric Midrange frequency select (Ch1&2)

7. Parametric Midrange Q factor (Ch1&2)

8. High frequency shelving cut and boost (Ch1&2)

9. Boost level (global)

10. Mix control

11. A/B footswitch

12. BOOST footswitch

13. Amp / Tuner / Headphone output level

14. MUTE / TUNE footswitch

13 14

4

6 Back Panel Controls and Features

PUSH

1 2 3 4 95 6 7 8 10 1211 1413 15 16 17 18

1. Universal 100-240VAC power supply input module

2. Ground lift switch

3. Ch1 DI output

4. Ch1 DI output source select

5. Ch1 DI output line / mic level select

6. Ch2 DI output

7. Ch2 DI output source select

8. Ch2 DI output line / mic level select

9. External Footswitch input

10. Amp Output

11. Tuner Output

12. Eects Insert

13. Amp Source Select switch

14. Ch1 input mic / line switch

15. Ch1 mic input

16. Ch2 line input

17. Ch1 line input

18. Ch1 & 2 input impedance select

7 Side Panel Controls and Features

MODE12VMID 2MID 1CH 2CH 1

LOIO

A-B

61 5432

HI HI

LO

48V ch2ch1

1 2 3 4 5 6

1. Dip Switch location diagram

2. Ch1 48V phantom power

3. Ch1 phase reverse

61 5432

4. Ch2 phase reverse

5. DIP switch controls

6. 1/8 mini headphone jack

5

8 Connecting Felix to Stuff

8.1 1/4” INSTRUMENT INPUTS, CH1 & CH2

INPUT 1 - This input is for connecting any instrument pickup,
electret mic or line source to Ch1. The connector is a standard
unbalanced 1/4” jack wired tip signal, sleeve ground. If you are
using this input, remember to select the ‘line’ setting of the
adjacent ‘mic/line’ switch. We recommend muting Felix before
changing the setting of the mic/line switch to avoid pops on
the output.

INPUT 2 - This input is for connecting any instrument pickup,
electret mic, or line source to Ch2. This input can also
accommodate two dierent signals from a dual source pickup
system on one TRS 1/4” cable. The connector is a standard TRS
1/4” jack wired tip signal to Ch2, ring signal normaled to Ch1,
and sleeve ground. If you are using this input, remember to
select the ‘line’ setting of the adjacent ‘mic/line’ switch.

Both Ch1 and Ch2 line inputs have 3 input impedance settings,
selectable from the toggle switch labeled ‘Z’ . The settings are:

Ch1: med - 1MΩ / hi -10MΩ / low – 10kΩ
Ch2: med - 1MΩ / hi -20MΩ / low – 332kΩ

Some pickups or sources are more sensitive to preamp input
impedances than others. For example, if you use a ‘Sunrise’
magnetic pickup, they prefer to connect with an input
impedance of 1MΩ. If you have an onboard preamp or a lower
impedance pickup, the input impedance setting will probably
make less of a dierence. In any case, we encourage you to try
dierent settings with your pickup or source. The dierence
may be noticeable or not, and should be set accordingly to
what sounds best to you. Always what sounds best to you!

8.2 CH1 XLR MIC INPUT

This input can accommodate any type of microphone, from
a SM57 to a large diaphragm condenser, even a ribbon mic.
The connector is wired pin 2 positive, pin 3 negative and pin 1
ground. 48V phantom power, if activated, is supplied on pins
2 and 3. If you are using this input, remember to select the
‘mic’ setting of the adjacent ‘mic/line’ switch. The side panel
phantom power switch should always be set to OFF whenever
connecting or disconnecting this input. We recommend
muting Felix before changing the setting of the mic/line and
48V switches to avoid pops on the output.

8.3 INSERT

The insert connection is a buered, unbalanced insert point of
the blended signal (post boost) for connecting outboard eects
to Felix. This allows mono outboard signal processing to be
placed in series with the blend signal, while still utilizing all of
Felix’s output capabilities. It is a 1/4” TRS connection, wired tip
to send, ring to return and sleeve to ground.

SEE WIRING DIAGRAM page 11

8.4 AMP OUT

This output is for sending an unbalanced, non-transformer

isolated output to a stage amp or anywhere else you may need
an additional unbalanced signal. This output has the added
benet of a level control, which is situated on the right side,
bottom row of controls on the top panel. This output is muted
when the MUTE / tune footswitch is activated.

Amp out can be sourced from either the blended signal or Ch2
alone, with the selection being made with the ‘amp source’
selector switch on the rearpanel.

8.5 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.

8.6 FS - FOOTSWITCH INPUT

This input is for connecting an external footswitch to operate
the top panel footswitch functions. This is provided for folks
who will keep their Felix in a rack, on top of an amp, mounted
to a mic stand, or anywhere up o the oor. This allows you
to connect a standard 2 way foot switch and access the MUTE
and BOOST / TOGGLE functions. These controls have a logic
‘or’ function, so if either the footswitch or the front panel
toggle is engaged, the associated function will be activated.
Felix utilizes and requires ‘normally open momentary’ type
footswitches.

SEE WIRING DIAGRAM page 11

8.7 DI OUTPUTS, CH1 & CH2

These two outputs are balanced and transformer isolated, for
sending Felix signals to a front of house, monitor console, or
any mixer or interface where balanced, isolated signal needs to
be sent. XLR pinout is: pin 2 positive, pin 3 negative and pin 1
ground.

Each output can be sourced from either its individual channel
only, or the blend of the two channels, adjusted by the ‘MIX’
control on the far right of the top panel controls. Source select
is via the ‘DI source select’ switch above each XLR output. Also,
each output has an adjacent level setting switch – line and
mic, depending on what input this source will be feeding. In
the ‘mic’ setting, the output is padded down -26dB to interface
properly with mic inputs at the console, the ‘line’ setting is not
padded for better level matching with line level inputs at the
console or interface.

8.8 HEADPHONE OUTPUT

This is a 1/8” mini style headphone jack for monitoring Felix
via your headphones, EIM, earbuds etc.. This output level is the
same as the amp out, so the top panel amp out level control is
used to adjust headphone volume as well. This output remains
active when Felix is muted, so you can plug in your IEM’s and
practice privately during long, boring soundchecks. This can
also be very useful for hearing a very detailed and isolated

6

representation of how your EQ settings are working.

8.9 100-240VAC POWER INPUT

Felix is powered by a universal AC power supply. This means
that no matter where your musical wanderings take you, you
can plug Felix in to the wall and it will work. And it also means
one less wall wart you’ll own in your life. All units are shipped

9 Operation

with a standard AC cable suitable for the country where it is
going. This is a standard, o-the-shelf IEC power cable, so in the
event you misplace the one that came with your Felix, you can
just borrow one from the soundperson or the bass player and
go.

9.1 WHERE TO PUT FELIX?

Great question. We recommend you put him wherever you
want. He will look very pretty when you rst pull him out of his
box, but trust us, he is 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 appropriately
heavy duty. As you may have surmised by now, the main
inspiration for this product was to have studio-grade audio
hardware, properly ruggedized to live on the stage oor or
mounted to a pedal board.

Also, we have included mounting holes on the underside for
a standard mic stand mounting ange (which can be found
at most larger music gear retailers). This allows Felix to be
mounted directly to the top of a mic stand. If you do chose
to keep Felix up o the oor, you can still access the BOOST/
TOGGLE and MUTE/ TUNE footswitch features by connecting an
external footswitch to the ‘fs’ jack on the rearpanel.

Now that you have picked a place for Felix to reside, it’s time to
make some sound.

9.2 USING THE XLR MIC INPUT CH1

Before connecting a microphone to Felix, make sure the Ch1
gain knob is turned all the way down and the side panel 48V
phantom power switch is set to o (pushed out). Then connect
your microphone and if 48V is needed, simply activate it with
the side panel 48V switch. Always remember to turn 48V
power ON after connecting your microphone and OFF before
disconnecting your microphone.

Gain range for this input is adjustable between +18dB and
+60dB via the top panel Ch1 GAIN control knob. Use the top
panel Ch1 signal / clip indicator to properly set the mic level.
The LED will light green with signal present, then will begin to
ash red when the channel is 12dB before clipping. This means
that occasional red ashes are ok, but if the LED is mostly red,
well then, you better turn it down.

9.3 INSTRUMENT / LINE INPUTS

These are the inputs you will use for connecting your
instrument(s) to Felix. There is a wide array of dierent pickup
types in the world: active electronics in an electric bass, passive
under bridge plate transducers, contact mics, soundhole
magnetics, etc.. We wanted to make sure Felix brought out
the best in all of them and accordingly, there are some useful

features that can help make that happen.

Because we designed Felix to play well with a wide array of
mics and pickups on a wide array of instruments, the gain
control sweep required is more than this single potentiometer
can provide. Accordingly, there is an internal jumper which
activates an 18dB pad on the Ch1 line input. The Ch1
microphone XLR mic input is not aected by this pad. This
pad jumper is set to ‘ON’ from the factory, which mostly
matches the gains of Ch1 and Ch2. If you are using a source
that requires more gain (e.g. a low output pickup on a delicate
acoustic instrument), you may need to open up Felix and set
this jumper in the ‘ON’ position. Or likewise, if the source you
are using is overloading this channel, you will probably need
to set the pad back to its ‘OFF’ position. This is easy to do! We
specically designed Felix’s chassis to make it easy to access
internal jumpers. Please refer to the jumper diagram and access
procedure on p. 12&13. See, aren’t you glad you’re reading this
manual? Us too.

WARNING: make sure to disconnect the power mains before
removing the Felix top panel to make jumper adjustments.

Using a Dual Source Instrument with a Single TRS Cable

The Ch2 input can accommodate two dierent signals from
a dual source pickup system on a single TRS 1/4” cable. The
connector is a standard TRS 1/4” jack and is wired:

• Tip signal to Ch2 input,

• Ring signal normaled to Ch1 input,

• Sleeve to ground.

This feature makes using a dual source pickup system very
convenient. Assuming your instrument is properly wired with
a TRS output jack, you can simply use a standard TRS cable to
connect both sources to Felix, then EQ and blend each signal
accordingly. The sonic results of this kind of acoustic pickup
system can be very excellent.

Input Impedance Selection

Both instrument inputs have 3 dierent impedance settings:

Ch1: med - 1MΩ / hi -10MΩ / low – 10kΩ
Ch2: med - 1MΩ / hi -20MΩ / low – 332kΩ

In general, most passive pickups will want to connect to a
higher impedance setting, while active pickups probably a
lower. Passive pickups generally will have more sensitivity to
input impedance, but there are no hard and fast rules. Check

7

with the manufacturer of your particular pickup system to see
if they recommend a specic input impedance for their device.
Ultimately, as is with so many things like this, the nal judge
of this setting should be your ears. Impedance mismatches at
this stage may not even be audible, or very subtle, or totally
apparent. But trust yourself here – nothing will break if you
have the wrong setting – just audition the 3 positions of the
impedance switch and if one sounds better over the other 2,
than that’s the correct setting. Yeehaa!

12V Power

Both Ch1 and Ch2 instrument inputs can be used to amplify
an electret capacitor microphone. These are common for
applications where small microphones are mounted inside
acoustic instruments, or lavalier style microphones used
somewhere on the outside of the instrument. Normally these
microphones will contain very small integrated preamps which
require a small voltage to power. So the Felix can send 12V
phantom power out on both of these inputs. This is activated
via DIP switch # 5 on the side panel.

12V power can be applied to the tip, ring or neither of each
channel’s input jack. Conguration is done via internal jumpers,
described in detail on pages 12 & 13.

NOTE: 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 Felix. And, as with 48V phantom power in the XLR
mic input, 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.

Phase Reverse

Both Ch1 and Ch2 have phase reverse switches, located on
the left side panel, directly next to the 48V phantom power
switch. Use these to toggle the polarity of either channel.
Experiment with these methodically – one at a time, to nd the
setting that sounds right. If you are blending two sources on
one instrument, you may nd that ipping the polarity on one
source or the other sounds best. If you are using Felix to toggle
between two dierent instruments, you probably won’t need
to mess with their polarity.

Phase relationships can be very complicated, and discrepancies
can result in highly accentuated or de-accentuated bass
response of a blended signal. Or it can sound hollowed out and
thin, or just downright weird. Again, 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 ipping 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
these controls and hear them in use with your instruments.

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 / Notch

This is the next control to the right of the GAIN knob for each
channel. To select between HPF and Notch, adjust the left side
DIP switch locations # 1 & 2 respectively for channels 1 & 2.

HPF: A High Pass Filter will only allow signal information above
its set frequency to pass downstream to the output. This
lter employs 12dB per octave roll o and uses a Thomson –
Butterworth response for the best combination of passband
atness and time domain response. Yes, that will be on the quiz.

GAIN

0dB

-12dB

Simply put, use the high pass lter to cut unwanted bass
frequencies out of a signal. Usually a HPF is used to eliminate
rumble or non-musical low frequency information out of a
signal. But this HPF range is from 20Hz to 1.0kHz, so you can
make very dramatic lter settings. Some instruments won’t
have any information below a certain frequency. Fiddle for
example only extends its lowest fundamental down to 200Hz.
So if you are amplifying a ddle, you could safely set the HPF at
150 – 200 Hz without hearing much eect in the tonality of the
instrument. Whereas a bass can have a low fundamental down
around 30Hz, so setting the HPF any higher than that could
aect its tonality.

If you are on a stage with an acoustic guitar, and there is lots of
low end making you sound bad, or feeding back or both, the
HPF might be your rst stop to try to control those problems.

Notch: A notch lter is a very sharp and deep cut of a specic
frequency. This is used predominantly to nd and remove a
specic problem frequency that may be feeding back through
stage monitors or amps, or to simply cut out a very specic,
narrow unwanted part of an instrument’s frequency range. This
notch uses the same frequency sweep of 20Hz – 1.0kHz.

40 125 20k1k

GAIN

0dB

HIGH PASS FILTER

NOTCH FILTER

Hz

9.4 FILTERING AND EQ

One of the truly dening features of our pal Felix is the
very powerful, fully independent EQ / lter controls on
each channel. Each channel has identical controls, so the
descriptions in this section apply to both Ch1 and Ch2.

If you haven’t used EQ’s or lters much, we will provide a basic

8

-12dB

Under normal operation, if you don’t have a use for a notch
lter, we recommend you leave the left side panel DIP switch in
the HPF setting. That way, with the HPF set in its fully counter
clockwise position, this entire lter control is eectively out of
the signal.

40 125 20k1k

Hz

Low

The Low control of the Felix preamplier is xed at 125Hz (+­3dB) corner frequency / 40Hz peak, with a gain range of -12
to +12dB. This is a xed shelving type control, which means
everything below the 125Hz is boosted or cut. Use this control
for cutting and boosting bass frequencies. It’s all about the
bass.

GAIN

+12dB

0dB

-12dB

Also, because certain acoustic instruments (banjo) may react
better to a higher corner / peak 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 / 80Hz peak. This is easy to do! We specically
designed Felix’s chassis to make it easy to access internal
jumpers. Please refer to the jumper diagram and access
procedure on pages 12 and 13. Bravo to you for reading this
manual. You get an A.

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

LOW SHELF EQ

40 125 20k12k

Hz

Mid

The mid range section of Felix’s equalizer is fully parametric,
which enables you control the mid range gain, frequency and Q
independently. The range of these controls are:

Gain = +/- 12dB,

Freq range LO setting = 70Hz – 880Hz

Freq range HI setting = 670Hz – 8.0kHz

Q = .5 – 5

The frequency range can be switched between the LO and
HI settings via the left side panel DIP switch locations # 3 & 4.
With these two available ranges, the over all range of the mid
controls is very wide, which enables targeting of specic sonic
areas of a multitude of instrument or pickup types.

0dB

MID EQ

20

Q

1k

20k

Hz

GAIN

+12dB

-12dB

Q factor determines the sharpness of the bandwidth of the
frequency being adjusted. A higher Q factor setting – turning
the Q knob further clockwise - creates a sharper bandwidth
and thus a more targeted, surgical EQ adjustment. Alternately,
a lower Q factor - turning the Q knob further counter clockwise

- creates a broader tonal adjustment.

High

The High control of the Felix preamplier is set with a 2kHz
(+/-3dB) corner frequency/ 12kHz peak, with a gain range of

-12 to +12dB. This is a xed 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.

GAIN

+12dB

0dB

-12dB

20

HIGH SHELF EQ

2.0k

Hz

20k12k

9.5 OUTPUT CONTROLS

Boost

Want Felix to go to eleven? How about twenty? 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 global,
so it is added to every signal output leaving Felix – blended
or individual channels, amp out or either ISO out, even the
headphone out.

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 o. Felix is not responsible for disgruntled
soundpeople you may encounter during the operation of the
boost circuit. He wants to keep those people happy, and you
should too.

Amp / Phones Output Level

This knob sets the output level of the unbalanced Amp and
tuner outputs on the rearpanel and also of the headphone
jack on the right sidepanel. 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.

If you are using the side panel headphone jack with the MUTE
switch activated, remember that headphone level adjustments
will also aect stage amp level, which could lead to a big nasty
sound on stage when un-muting Felix outputs. Simply make a
note of your stage amp level before making adjustments to this
control while headphone monitoring.

Mix

This control adjusts the mix, or blend, between Ch1 and Ch2.
Before using this control, its important to verify if Felix is
Blend or A/B mode. This setting is toggled via the side panel

9

DIP switch #6. With the switch in MIX mode (the downward
position), this control will operate normally as a simple mixer.
With this knob turned fully counter-clockwise, the outputs
(set to mix) will be sending 100% Ch1. With the knob turned
fully clockwise, the outputs will be sending 100% Ch2. With
the knob centered at 12 o’clock, the outputs with be sending a
50/50 blend of Ch1 and Ch2.

Remember, if you intend to blend Ch1 and Ch2, you must
set the DI output(s) or Amp output to ‘mix’ mode via the
pushbutton toggle switches on the rearpanel.

If Felix is set to A/B mode via the left side panel DIP switch #6,
then this control will have no eect.

9.6 FOOTSWITCH CONTROLS

Blend – A/B

This is the far left foot switch on Mr. Felix. If the unit is set to
blend mode via DIP switch # 6, then this switch will do nothing,
and both adjacent LEDs will be permanently illuminated. If the
unit is set to A/B mode, then this switch will be used to toggle
between Ch1 and Ch2, with the accompanying amber LEDs
lighting and extinguishing accordingly. This toggle mode is
exclusive, so if you have Ch1 selected, Ch2 will be muted and
vice versa.

Boost

You guessed it. This switch activates the Boost circuit, at the
level you set with the upper row ‘boost’ knob. This circuit is
global, so the boosted signal will be coming out of every
output. For those about to rock, kindly activate this switch rst.
The LED will light up GREEN for go.

Mute / Tune

This switch mutes all Felix outputs (ISO 1, ISO 2 and AMP)
except the tuner and headphone outputs. This enables you
to quickly and easily cut your signal to tune or unplug your
instrument without having to have the soundperson mute your
channel.

When MUTE / tune is active, the adjacent LED illuminates RED.

9.7 SIDE PANEL CONTROLS

Felix has a lot going on, more than we could t on the rear
and top panels alone. So there are a number of features to be
familiar with on the side panel.

Ch1&2 Phase Reverse

These two pushbutton toggle switches reverse the polarity of
each channel’s audio signal. To reverse the polarity of either
channel, simply push the toggle in, to return to no polarity
reverse, push the toggle again to return it to it’s outer position.

48V Phantom Power

This activates 48V phantom power for the Ch1 microphone
preamplier. Phantom power is sent out on pins 2 and 3 of the
XLR connector.

DIP Switches

This is a bank of 6 DIP switches, used to activate various modes
or settings. Switches 1 & 2 select between Ch1 & Ch2’s HPF or
notch setting. Switches 3 & 4 select between Ch1 & Ch2’s mid
EQ’s frequency range, LO or HI. Switch 5 activates 12V power on
the instrument inputs. Switch 6 selects between blend or A/B
mode.

DIP switches are hard to adjust, which is good because they
probably won’t get inadvertently changed, but bad when you
actually want to change them. Use the edge of a ngernail, 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.

Headphone Jack

This is a standard 1/8” mini headphone jack, suitable for
most types of headphones. It is left / right mono, and follows
whatever signal is present at the AMP output. The level control
for this is the Amp / phones knob on the right side of the top
panel. This output is always active, even if the top panel MUTE
/ tune switch is activated. This way you can play or practice
privately with your headphones on while your stage outputs
remain muted. Bandmates will be relieved, soundpeople will be
happy. Kumbaya, etc...

10

10 Diagrams

GND

1/4" TRS PLUG

TIP

SLEEVE

To Felix Insert Jack

SEND

RETURN

1/4" TS PLUG

1/4" TS PLUG

To Outboard Input Jack

To Outboard Output Jack

GND

RING

GND

1/4" TRS PLUG

TIP

SLEEVE

To Felix footswitch jack

BOOSTMUTE

RING

10.1 INSERT CABLE WIRING

10.2 EXTERNAL FOOTSWITCH WIRING

11

10.3 ADJUSTING INTERNAL JUMPERS

Several Felix 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 ne. 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:

1. IMPORTANT: Before you do anything, disconnect

Felix from the AC power, and disconnect
instrument and mic cables and place Felix on a at

stable surface with good lighting.

2. DOUBLE CHECK: Did you completely disconnect the power

supply? Ok then.

3. 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.

4. Orient the unit so the rearpanel is facing forward. Carefully

pull up on the top chassis and ip it up and over the
bottom chassis. 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 ipped over and behind the
bottom chassis. See gure 2.

5. Now refer to the jumper location diagram on the following

page to move any jumpers you wish.

6. To move a jumper, use tweezers or your ngernails to

gently pull the jumper o of it’s header pins. To reposition
the jumper, double check the diagram, then gently press
the jumper back down in the correct location.

7. J2, J17, J18 all reside on 2-pin headers. If you wish to set

these to a non-jumpered setting, simply push one side of
the jumper down onto one pin, so that the two pins are
not connected.

Fig. 2 opening the chassis

8. When you are nished adjusting the jumpers, make sure
there are no loose jumpers or any other junk lying around
inside your Felix.

9. 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 tting
properly, carefully pull the top and bottom back apart and
inspect for interference.

10. 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.

11. Do not tighten the screws until all 4 are cleanly started in
the threads. Take your time and remember, cross-threading
is a crime.

Fig.1 removing the chassis screws

12

If you get stuck or something doesn’t look right, call us right
away and we’ll get you taken care of.

10.4 INTERNAL JUMPER LOCATIONS

J18

J18

J17

J17

J23

J23

J18 - Sets the Ch1 EQ LOW corner frequency. LO position is 125Hz, HI position is 250Hz.

J17 - Sets the Ch2 EQ LOW corner frequency. LO position is 125Hz, HI position is 250Hz.

J6
J7

J2

J6

J7

J2

J23 - Sets the secondary external footswitch function. Options are boost, toggle or disable. Primary footswitch function is xed as
MUTE / TUNE.

J6 and J7- Congures 12V power, which can be applied to either channel’s tip, ring, or set to o. Set these according to how your
microphone / instrument is wired.

J2 - Sets the Ch1 instrument input gain range. Options are LO (3-44dB)and HI (21-62dB).

13

10.5 BLOCK DIAGRAM

D D

C C

B B

A A

UNBALANCED IN

CH2 1/4"

1

RING

TIP

(TIP / RING / OFF) VIA JUMPER

CH 2 +12V MIC POWER

+12V ON/OFF

UNBALANCED IN

CH1 1/4"

TIP

(TIP / RING / OFF VIA JUMPER)

CH 1 +12V MIC POWER

XLR MIC INPUT

CH1 BALANCED

1

+48V PHANTOM POWER

CH1 1/4" JACK SWITCH

CH1 LO/HI GAIN

CH 1 INPUT

IMPEDANCE

VIA JUMPER

CH 2 INPUT

IMPEDANCE

2

3

FOOTSWITCH

INTERNAL JUMPER SETTING

REAR PANEL TOGGLE SWITCH

REAR PANEL PUSHBUTTON SWITCH

SIDE PANEL DIP SWITCH

CH2 SIG / CLIP INDICATOR

CONTROL TYPES:

FRONT PANEL KNOB

SIDE PANEL PUSHBUTTON SWITCH

CH 2 GAIN

CH 2 POLARITY

CH 2 HPF / NOTCH

CH 2 HPF / NOTCH

FREQ SEL

SEL

CH2 LO/HI RANGE

CH 2 LOW FREQ

BOOST / CUT

VIA JUMPER

CH 2 LO/HI RANGE

CH 2 MID FREQ

CH 2 MID FREQ

CH 2 MID FREQ

BOOST / CUT

FREQ SEL

Q

CH1 SIG / CLIP INDICATOR

LINE / MIC

CH 1 GAIN

CH 1 POLARITY

CH 1 HPF / NOTCH

CH 1 HPF / NOTCH

SEL

CH1 LO/HI RANGE

CH 1 LOW FREQ

BOOST / CUTFREQ SEL

VIA JUMPER

CH 1 MID FREQ

CH 1 MID FREQ

BOOST / CUT

FREQ SEL

Q

+48V ON/OFF

2

3

CH 1 LO/HI RANGE

CH 1 MID FREQ

CH 2 HIGH FREQ

BOOST / CUT

BOOST ON/OFF

BOOST GAIN

4

Grace Design and Lunatec LLC. This diagram is provided for reference purposes

only. Any duplication, disclosure to third parties or unauthorized use is forbiden.

Drawn by:

Date:

Size:

PROPRIETARY © Grace Design/Lunatec LLC This diagram is the property of

m302 INSTRUMENT PREAMP / BLENDER

C

*

CH 1 / CH 2 TOGGLE

TOGGLE MODE

CH 1 HIGH FREQ

BOOST / CUT

4

JEK

File:

m302_block_diagram_20140207.SchDoc

Date modified:

Checked by:

*

5

6

4/13/2015

SOURCE SEL

Rev.

No.

*

02

Sheet of

1

1

© Grace Design/Lunatec LLC All rights reserved

GRACE DESIGN

LYONS, CO 80503 **

4689 UTW HWY

CH 1 / CH 2 TOGGLE

BOOST ON/OFF

(VIA JUMPER)

MUTE / TUNE

OR

EXTERNAL FOOTSWITCH INPUT

RING

TIP

RING = RETURN

TIP = SEND

TUNER UNBALANCED OUT

MONO HEADPHONE OUT

AMP UNBALANCED OUT

AMP

AMP OUTPUT LEVEL

INSERT

CH 1 / CH 2

BLEND

SOURCE SEL

ISO2

ISO2 OUTPUT TRANSFORMER

ISO1 OUTPUT TRANSFORMER

ISO2 MIC / LINE LEVEL

ISO2 BALANCED OUT

GROUND LIFT

SOURCE SEL

ISO1

ISO1 MIC / LINE LEVEL

MUTE / TUNE

ISO1 BALANCED OUT

5

6

14

10.6 CONNECTION DIAGRAM

monitor mixer, recorder, workstation, yadda fed by DI 2 output. Sourced by mix or Ch2

amp

FOH mixer fed by DI 1 output. Sourced by mix or Ch1

FELiX connections

Nothing too terribly hard and fast here - just the basics about how to plug stu in and out of

your preamp. There are many ways to connect a huge array of instrument sources to FELiX. If

you aren’t sure about how something works, please have another look at your owner’s

manual, check out our website - www.gracedesign.com - or feel free to call us. We are always

glad to help out in any way we can. 1.303.823.8100, M-F, 9-5 MST

plug FELiX into nice,

clean AC power

reverb

out input

input

stage amp fed by amp out

external eects routed

through the insert

instrument mic, vocal mic

plugged into mic input 1

control mute and boost

fed by tuner out

PUSH

side panel headphone jack

external footswitch to

footswitch

stage tuner

acoustic or electric instruments with pickups or internal mics plug into Ch1 or Ch2 inputs

external

tuner

out input

A

15

11 Specifications

GAIN RANGE (Input to DI Output)
CH1 MIC 21-62dB
CH1 Inst Low Gain: 3-44dB / High Gain / 21-62dB
CH2 Inst -1.5-36.5dB
Boost 0-9dB
THD+N 1kHz, 22Hz-22kHz BW (MIC Input to DI Output)
@ 20dB Gain +10dBu out <0.0045%
@ 40dB Gain +10dBu out <0.0050%
@ 60dB Gain +10dBu out <0.010%
INTERMODULATION DISTORTION - SMPTE/DIN 4:1 7kHz/50Hz (MIC Input to DI Output)
@ 40dB Gain +10dBu out <0.05%
NOISE - REFERRED TO INPUT CH1 MIC @60dB Gain 22Hz-22kHz BW
50Ω source <-128dB
CMRR @60dB Gain
100Hz >55dB
1kHz >75dB
10kHz >75dB
FREQUENCY RESPONSE (Input to DI Output)
Mic input @ 40dB Gain -3dB 20Hz – 65kHz
Inst input @ 20dB Gain -3dB 20Hz – 65kHz
I/O IMPEDANCE
CH1 MIC Input 8.1kΩ
CH1 Inst Input HI: 10MegΩ / MED: 1MegΩ / LOW: 10kΩ
CH2 Inst Input HI: 20MegΩ / MED: 1MegΩ / LOW: 332kΩ
Insert Input 10kΩ
DI Outputs 150Ω
Amp, Tuner, Headphone and Insert Outputs 150Ω
SIGNAL / PEAK LED METER
Green threshold -10dBu
Red threshold +10dBu
MAXIMUM INPUT LEVEL
CH1 MIC 0dBu
CH1 Inst Low Gain: +21dBu / High Gain: 0dBu
CH2 Inst +20.5dBu
MAXIMUM OUTPUT LEVEL - 100k Ohm load, 0.1% THD
DI Outputs Line: +20dBu / Mic: -6dBu
Amp, Tuner, Headphone and Insert Outputs +22dBu
High Pass Filter / Notch Filter
High Pass Filter 20Hz – 1kHz @ -12dB/octave
Notch Filter 20Hz – 1kHz, >-35dB, Q>1.0
EQ
Gain +/- 12dB
Low Frequency Low Range: 125Hz Shelving / High Range: 250Hz Shelving
Mid Frequency Low Range: 70Hz – 880Hz / High Range: 670Hz – 8kHz
Mid Frequency Q 0.5 – 5
High Frequency 2kHz Shelving
OUTPUT NOISE 22Hz-22kHz BW @ MIN Gain
CH1 MIC Input (50 ohms) to DI Output <-88dBu
CH1 Inst Input to DI Output <-88dBu
CH2 Inst Input to DI Output <-98dBu
EXTERNAL FOOTSWITCH
MUTE (TIP) Momentary – Normally Open – Switch to GND < 10Ω
BOOST / TOGGLE (RING) Momentary – Normally Open – Switch to GND < 10Ω
POWER CONSUMPTION
100-240VAC 50/60Hz 10 Watts Max
WEIGHT and DIMENSIONS

3.2lbs H3.0” x W9.5” x D5.5”

16

12 Cleaning and Maintenance

Your Felix 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 nd 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.

13 Warranty

• Grace Design warrants this product to be free of defective parts and workmanship for a period of ve 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 modication, 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 ecient 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 [phone] 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 prots 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 specic 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.

17

14 Manual Revisions

Revision Page Change Date Initials

A all Initial release 05/08/2015 edg

18