Black Box HG-2 User manual

rev. 3.0

MIX BUS, MEET YOUR NEW BEST
FRIEND
Looking for the piece of gear that gives you that elusive “magic” on your mix
bus? We were too! We went through everything from high end summing
mixers to racks of insanely expensive gear and most of it barely did anything
(you had to sit on the edge of your seat and strain to see if you could tell the
dierence)! Even when we did nd combinations that got us close to what we
were after, it meant tens of thousands of dollars in gear and using each piece
for very little (sometimes using a piece of gear only for it’s transformers). Most
frustrating of all, it meant lots of controls with none of them directly focused
on doing what we were after. This was 2009 and it became obvious that no
one made what we were looking for so we created Black Box Analog Design and
spent the next ve years designing the HG-2.
The HG-2 is specically and uniquely designed to be an all in one unit capable
of giving you all the vibe, harmonics, saturation, tonal enhancement and RMS
you could want on the mix bus. With simple, intuitive controls, no compromise
components and unique features not seen on any other piece of gear, the HG-2
replaces many pieces of gear and simplies mixing.
From extremely subtle harmonic enhancement of the tubes and Cinemag
transformers to RMS pushing saturation, full on distortion and natural tube
compression, the HG-2 is designed to give you full control over the “mojo” on
your mix bus. It also happens to sound awesome on instruments and as a front
end for synths and other stereo sources!
Robert & Eric

1
ANALOG DESIGN
IMPORTANT SAFETY INFORMATION
READ ALL INSTRUCTIONS BEFORE USE
WARNING!
For your safety, the information in this manual
must be followed to minimize the risk of electric
shock. Failure to do so may result in property
damage, injury or loss of life.
IMPORTANT SAFETY INSTRUCTIONS
WARNING:
This device contains high voltage electricity
capable of delivering lethal shocks if used improperly.
Never, under any circumstances operate this unit without being
connected to a properly grounded circuit! If you are unsure,
consult an electrician to make sure your outlet is properly
grounded before plugging the unit in.
Do not attempt to service unit or open the case for any reason.
Internal capacitors are capable of delivering dangerous shocks
even after the unit has been unplugged.
• Never defeat ground using a ground lift or other device.
• Never expose unit to moisture or water
• Do not plug in or operate unit if it is visibly damaged.
• Never replace fuse with a fuse of a dierent rating.
•
•

2
ANALOG DESIGN
WHAT DOES THIS BUTTON DO?
CONTROLS
D
8
7
6
5
4
3
2
1
ON
OFF
SATURATION
IN/OUT ALT TUBE
LOW FLAT HIGH
Sat. Freq.
AIR BYPASS
VU PPM
HG-2
TRIM
L R
1
2
34
5
6
7
8
9
10
11
Brings the parallel saturation circuit in or out
Saturation pot adjusts how much of the parallel saturation signal is fed into
the main signal path
Switches between two sets of 12AX7 tubes in the parallel saturation circuit
Pentode gain control
Selects between VU and PPM meter modes
Triode gain control
Engages or disengages high frequency “air” lift
Left / Right ne trim adjust
True bypass switch shorts input XLRs directly to output XLRs
3 way power switch with O/Standby/On positions: Standby mode sends
power to the tube heaters and LEDs
1
Sat. Freq. chooses which frequencies are present in the parallel sat. circuit
2
3
4
5
6
7
8
9
10
11
12
Passive output attenuation
12

3
ANALOG DESIGN
D
8
7
6
5
4
3
2
1
ON
OFF
SATURATION
IN/OUT ALT TUBE
LOW FLAT HIGH
Sat. Freq.
AIR BYPASS
VU PPM
HG-2
TRIM
L R
13
14
15
16
17
IEC power socket
13
Master on/o switch: In the “o” position, no power will reach the face plate
and the front panel power switch will be inoperable. Be aware that in the
“on” position, power is present inside the box even when the power switch
on the front panel is in the“o” position.
14 2AG power fuse: Replace only with the same rating fuse (5 amp slow blow)
15
Balanced line input
16
Balanced line output
17
LEFT RIGHT

WHAT CAN THE HG-2 DO?

5
ANALOG DESIGN
INTRODUCTION
WHAT CAN THE HG-2 DO?
Add Harmonics and Saturation (in multiple ways)
The main signal path of the HG-2 travels from the input transformers to the
Pentode amplication stage, on to the Triode amplication stage and nally to a
passive output attenuation before hitting a pair of Cinemag output transformers.
The tubes naturally produce pleasing harmonics but each stage (Pentode and
Triode) are voiced to produce more and more harmonics and eventually saturation
as you drive them harder. Driving the Pentode quickly produces harmonics
while pushing the Triode saturates the signal in a very pleasing way.
Along with the main signal path, the HG-2 also has a parallel path that
splits o directly from the input transformers. This parallel path is fed into
a pair of 12AX7 tubes, voiced for their own pleasing harmonics. The “saturation”
knob allows you to mix in as much of this parallel signal as you want with the
“dry” signal before being recombined at the Pentode stage. These three knobs
(Saturation,Pentode and Triode) give you full control over how much and what
type of saturation and harmonics you add.

6
ANALOG DESIGN
INTRODUCTION
Shape Tone
In addition to being another source of harmonics and saturation, the parallel
saturation circuit also opens up tonal possibilities. The 3 way “Freq. Select”
switch gives the user the option to choose what frequencies are present in the
parallel saturation circuit. The “low” position feeds the circuit only lows and low
mids, the “high” position feeds the circuit only the highs and high mids and the
“at” position feeds full bandwidth. This allows the user to add body and weight
to the low end of tracks by mixing in the saturated signal and harmonics only in
the low end or add sizzle, bite and harmonics only to the top end of dull tracks.
The “air” switch is a gentle lift starting at 10kHz.
Instantly Switch between Tubes
The “alt tube” button instantly switches between two sets of parallel
saturation tubes. The “alt” tube is voiced slightly more aggressively allowing for
even more exibility when using matched tubes but the tubes can be swapped
with any 12AX7 tubes, allowing the user to try dierent tubes and switch between
them in real time, at the push of a button.
Increase RMS of your signal
The same controls that allow you to enhance your signal with harmonics,
also allow you to increase the RMS of your signal by pushing the tubes into
saturation and natural compression. Each tube stage is specically setup to
have a range that goes from clean reproduction of the signal to full saturation
where the peaks are compressed and the average level is increased. Since each
stage feeds the next (parallel saturation feeds Pentode which in turn feeds the
Triode), the stages interact in a very useful way. In other words, if you set the
Pentode and Triode to just before where they begin to saturate, adding signal
from the parallel saturation circuit or driving the Pentode harder will push the
Triode into saturation. You can then push the Triode itself harder which will in turn
produce more compression, increasing your perceived level while maintaining
your peaks. Similarly, pushing the parallel saturation circuit hard will allow you
to achieve compression at the Pentode stage which can then be used to push the
Triode as hard as you like from clean to further compression.

7
ANALOG DESIGN
GETTING STARTED
WHAT SETTING SHOULD I START WITH?
When setting up the HG-2, start with a neutral setting that closely matches the
original signal. To match, use the bypass to switch back and forth as you make
adjustments.
Pentode: 12 o’clock
Triode: 10-11 o’clock
Output: Adjust until levels match when bypassed
Parallel sat circuit: O
Air: O
NEUTRAL SETTING*
* It’s important to remember that the HG-2 is designed to saturate, so how
hard you drive into it aects the settings. The above settings will be neutral
for the vast majority of unmastered mixes. If your track is extremely hot or
low in volume, adjust the signal feeding the input of the HG-2.
Adjusting the Pentode and Triode
From the neutral setting, begin by increasing the Pentode gain. This will
increase the Pentode harmonics and eventually begin gentle saturation. As
you turn the Pentode up, turn the Triode down to compensate. Now go back to
the neutral setting and turn the Pentode up again but this time, use the output
attenuation to compensate. Notice the dierence in response.
Starting again from the neutral position, increase the triode gain, using
the output volume to compensate for the volume dierence. Continue to
experiment with driving both the Pentode and Triode in dierent amounts until
you nd a setting you like.
Adding the parallel saturation circuit
Once you have a Pentode and Triode setting you like and your output level peak
matched, make sure the “Saturation”knob is all the way down and the “Sat.
Freq.” switch is in the “at” position, then engage the parallel saturation circuit
via the “in/out” switch. Slowly turn the knob clockwise to mix in more of the
saturated signal and keep watching your peak meters. You will notice that how
much increase in peak or RMS levels you achieve is dependant on the settings
of the Pentode and Triode. If the Pentode and Triode are in a very “clean”
setting, the parallel saturation circuit will add both peak and RMS. If the
main path is already in saturation, the parallel saturation circuit will further
saturate the signal, resulting in higher RMS without much peak gain.

8
ANALOG DESIGN
GETTING STARTED
The “air” boost is a gentle high frequency lift that begins around 10khz and gently
increases as it approaches 20kHz. The boost is inserted in the main signal path, at
the Triode gain stage.
Shaping tone
In addition to the harmonic and saturation control, the HG-2 also allows the user
to shape tone via the“tilt” selector and the“air” switch.
The “Sat. Freq.” selector
The 3 position “Sat. Freq.”selector is a simple yet powerful feature that allows the
user to choose what are present in the parallel saturation circuit.
In the “Flat” position, full bandwidth is fed into the circuit, allowing for
saturation of all frequencies.
In the ”Low” position, only the low mid and bass frequencies are fed into the
circuit. This allows the user to add body and weight to recordings.
In the ”High” position, only high mid and high frequencies are fed into the
circuit, allowing the user to add sizzle, presence and top end.
“Air” boost
The “Alt tube” selector switches between two sets of 12AX7 tubes in the parallel
saturation circuit. The “alt” tube is voiced slightly more aggressively, giving
the user a wider range of tones and saturation types. Both 12AX7 tubes can
be swapped for any 12AX7s for even more exibility. The user can then switch
between them instantly.
“Alt tube ”

D
8
7
6
5
4
3
2
1
ON
OFF
SATURATION
IN/OUT ALT TUBE
LOW FLAT HIGH
Sat. Freq.
AIR BYPASS
VU PPM
HG-2
TRIM
L R
SESSION: ____________________________________________ DATE: _______________
NOTES:
TRACK: ______________________________________________