Joranalogue AUDIO DESIGN Enhance 2 Stereophonic User Manual
- June 5, 2024
- Joranalogue AUDIO DESIGN
Table of Contents
Joranalogue AUDIO DESIGN Enhance 2 Stereophonic
INTRODUCTION
Moving from mono to stereo sound: a logical progression for any synthesist
looking to expand their sonic palette. Making use of two audio channels,
rather than just one, quite literally adds another dimension to the
capabilities of a synthesizer.
Unfortunately, controlling stereo signals can be a challenge within a modular
system. This realization led to the development of Enhance 2: a convenient yet
high-fidelity tool for stereo enhancement. It can be used to adjust the
balance, width, and spectral content, while also opening up a world of
mid/side processing; all under voltage control and in just 8 HP.
The primary stereo parameters are balance (moving the sound left or right) and
width (making it narrower or wider). The balance circuit uses a true constant-
power gain law, while the width stage allows for seamless transitions from
pure mono to extra-wide stereo.
In addition, the tone control is provided by a pair of unique, wide-ranging
mid/side voltage-controlled tilt filters with selectable corner frequency.
These make ‘cleaning up’ a muddy-sounding mix straightforward, but also
provide unique binaural effects when modulated.
Mid/side processing encodes the stereo signals into one containing only the
mono-material (mid), and another containing the differences between both
channels (side). Apart from the internal tilt filters, mid/side outputs also
enable external signal processing such as compression or reverberation. An
integrated mid/side decoder returns the results back to standard stereo. And
at all times, a LED bar phase meter ensures that phase correlation can be
easily maintained.
Stereo field modulation, mid/side equalization, and beyond; Enhance 2 brings
true analog stereo control to the Eurorack world.
CONTENTS
In the Enhance 2 box, you’ll find:
- Product card, stating serial number and production batch.
- 16-to-10-pin Eurorack power cable.
- Mounting hardware: two black M3 x 6 mm hex screws, two black nylon washers, and a hex key.
- The Enhance 2 module itself, in a protective cotton bag.
If any of these items are missing, please contact your dealer or [email protected].
CONTROLS & CONNECTIONS
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PHASE CORRELATION METER
The phase correlation meter is used to gauge the similarity of the left and right stereo output channels. The correlation figure can range from +1 (fully correlated, so no stereo content, only mono), through 0 (no inter-channel correlation) to −1 (the two channels are completely in anti-phase).
A good stereo image is achieved with a correlation factor between 0 and +1. A negative correlation, however, indicates a phase issue and is to be avoided. In this case, sound would be lost if the stereo channels were to be mixed into mono (for example, loss of bass during playback on a mono speaker or a subwoofer-equipped sound system).
Note that at least 100 mVpp of the signal is required on both channels to ensure correct phase readings. -
BALANCE KNOB AND CV INPUT
Use the balance control to shift the stereo image left or right.
The gains of both channels are controlled according to a carefully tailored balance law. The opposing channel will be maximally attenuated (approximately −40 dB) when set to either extreme position, while the selected channel will be boosted by +3 dB to maintain constant loudness. Set to the center position, both channels remain at unity gain. This parameter can be voltage modulated using the corresponding CV input. With the balance knob centered, the stereo image will shift fully left for a CV of −5 V, or fully right at +5 V. -
WIDTH KNOB AND CV INPUT
The width knob adjusts the overall ‘stereos’, from 0 % (mono mix), through 100 % when set centrally (no change to the stereo image), and beyond up to 200 %.
The width CV input is used to modulate this parameter at 20 %/V. You can achieve extremely wide stereo sound this way, but keep an eye on the phase correlation! -
MID/SIDE TILT KNOBS, SWITCHES, AND CV INPUTS
Enhance 2 uses mid/side processing, a powerful technique for sculpting stereo material. Two new channels are derived from the stereo pair: the mid-channel contains only the centered material that is common to the left and right, while the side channel isolates the stereo content which differs between both sides. This makes for very intuitive processing.
The tone of each of these channels can be easily adjusted using the tilt filters. They smoothly morph from a +6 dB bass boost and full treble cut when set fully counter-clockwise, to a full bass cut and +6 dB treble boost when set fully clockwise. The center positions are flat (unity gain).
The corner frequency for each filter can be toggled between bass (250 Hz) and treble (1 kHz) using the range switches.
Modulate the tilt filters using the CV inputs. Moving from flat to either extreme tilt requires a 5 V change in CV. -
STEREO INPUTS
Connect your pair of stereo source signals here. The entire signal path is DC- coupled.
Mono signals can be processed using just the left input socket, as there is normalization to the right. Keep in mind that in this case, due to the lack of stereo content, only the balance and mid tilt features will be functional. -
MID/SIDE OUTPUTS
These are the mid/side outputs of the stereo processor. You can use these for further mid/side processing using external modules.
Keep in mind that for most stereo signals, the mid signal will be much stronger, as there is typically more mono than pure stereo material; or in other words, a high phase correlation.
Both outputs are inverted with respect to the input signals. -
MID/SIDE INPUTS AND STEREO OUTPUTS
This mid/side decoder allows you to convert a mid/side pair back to stereo. It is fully independent of the stereo processor, except for the normalization from the processor’s outputs to the decoder inputs.
This means that if you do not wish to perform any additional mid/side processing, you can simply use the module’s stereo inputs and outputs directly. Otherwise, you can plug your processed mid/side pair into this decoder and get standard stereo outputs. External processing of only the mid or the side channel is possible as well.
Note that the phase correlation meter uses the decoder’s stereo outputs as its source pair. This means that the meter will also take in account any external mid/side processing that may influence the phase correlation.
Also be aware that while Enhance 2’s entire signal path is DC coupled, the meter will only respond to audio frequencies. To complement the module’s inverting mid/side outputs, this decoder is inverting as well, restoring the proper phase relationship of your stereo signals.
PATCH IDEAS
STEREO MIX WIDENER
The most obvious application for Enhance 2 is that of stereo mix widening.
However, a full mix cannot simply be made wider without risking phase
correlation issues. It is also important to keep psychoacoustics in mind:
higher audio frequencies are perceived as being much more directional than low
ones, limiting the benefits of widening bass frequency content.
The tilt filters allow you to adjust the spectral stereo field accordingly.
Plug your stereo pair into the input sockets. Center the balance and width
controls, and toggle both frequency switches to the bass setting. Next, set
the mid tilt knob to 9 o’clock, and the side one to 3 o’clock. This will boost
the mid-channel bass frequencies and simultaneously attenuate the treble.
Meanwhile, the side channel undergoes the opposite operation, ensuring that
nearly all bass content in the final mix is mono. Now you can widen the stereo
field by adjusting the width control beyond its center position. Experiment
with different filter settings to achieve anything from subtle, natural-
sounding widening to drastic stereo effects.
LINEAR VCA WITH TONE CONTROL
Enhance 2 can be used as a simple linear VCA in patches where no stereo
processing is required. Center all knobs and connect your input signal to the
right stereo input. The width knob and CV input will then affect the output
amplitude on the right stereo output, with +5 V corresponding to unity gain if
the knob is set to its minimum setting. Without any CV, unity gain is reached
when the knob is centered.
Additionally, the side filter can be used to add spectral control to the VCA.
The balance parameter also allows for amplitude control. However, the response
will be non-linear, as a result of the constant-power balance control law.
STEREO TILT FILTERS
While by default the tilt filters are configured in a mid/side pair, stereo
tilt filtering is possible as well, adjusting the tone of the left and right
channels directly.
To achieve this, center all knobs and patch your stereo input signals into the
module’s mid/side input sockets. Next, connect the stereo outputs to the
stereo inputs. The mid/side outputs are used as the true stereo output pair.
By exchanging the mid/side encoders and decoders this way, the module’s signal
path is effectively ‘swapped around’. The mid tilt filter now only affects the
left channel, while its side counterpart affects the right.
Note that the balance control will influence the stereo width instead, while
the width knob can be used to attenuate or amplify the right channel and thus
change the balance. The correlation meter essentially becomes meaningless.
PHASE METER
Apart from measuring the correlation between the two channels of a stereo
signal, Enhance 2’s phase correlation meter can also be used to measure the
phase shift between two otherwise identical signals.
Simply center all knobs and plug both signals into the left and right input
sockets. 30° of phase difference is represented between adjacent LEDs. This
means that if, for example, the two signals are 90° out of phase, the ‘0’ LED
will light up. Both signals are passed through unaltered to the stereo output
sockets on the bottom right of the module.
SPECIFICATIONS
Module format
Doepfer A-100 ‘Eurorack’ compatible module 3 U, 8 HP, 30 mm deep (inc. power
cable) Milled 2 mm aluminium front panel with non-erasable graphics
Maximum current draw
- +12 V: 70 mA
- 12 V: 70 mA
Power protection
Reverse polarity (MOSFET)
I/O impedance
All inputs: 100 kΩ
All outputs: 0 Ω (impedance compensated)
Outer dimensions (H x W x D)
128.5 x 40.3 x 43 mm
Mass
Module: 115 g
Including packaging and accessories: 200 g
SUPPORT
Like all Joranalogue Audio Design products, Enhance 2 is designed,
manufactured, and tested with the highest standards, to provide the
performance and reliability music professionals expect.
In case your module isn’t functioning as it should, make sure to check your
Eurorack power supply and all connections first.
If the problem persists, contact your dealer or send an email to
[email protected]. Please mention your serial
number, which can be found on the product card or on the module’s rear side.
With compliments to the following fine people,
who helped to make Enhance 2 a reality!
- Björn Jauss Boris Uytterhaegen
- Daniel Miller Frits Jacobs
- Gregory Delabelle Jan D’Hooghe
- Janus Coorevits Jérémy Bocquet
- Jeroen De Pessemier Lieven Stockx
- Marcin Staniszewski Quincas ‘Synth DiY Guy’ Moreira Rick Van Oss Sebastiaan Tulkens