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[[File:Hordijk de.png|thumb|200px|Panel design for an early Rob Hordijk DUAL ENV]]The '''DUAL ENV''' is a module by [[Rob Hordijk Design|Rob Hordijk]]. It features two paired envelopes with different shapes, ENV A is a four-stage (attack, decay 1, break level, decay 2, release) and ENV B a two-stage (attack, decay). It also features a Sample and Hold function. There have been a few versions with different envelope stages, toggle switches, and modulation possibilities.
Contact Rob directly for details about his modules: rhordijk@xs4all.nl. <br>


Both envelope generators share the same gate input, meaning that they can not be triggered separately, though in later versions ENV B featured a toggle switch to allow self-cycling. This also features two LEDs to indicate the gate status of each envelope.


Triggering threshold is roughly 100mV above ground, and can be triggered by wave forms other than pulses, e.g. triangle waves.<ref name="rh">Rob Hordijk</ref>
Rob also has a subforum at the Electro-Music forum site:
http://electro-music.com/forum/index.php?f=185


=== ENV A ===
[[File:Hordijk de fc.png|thumb|200px|A flow chart explaining the functionality of the DUAL ENV]]The ADBDR envelope is primarily intended to be used for volume envelopes. When the decay2 knob on the first envelope generator is fully open the decay2 acts like the sustain that you find on most of the traditional envelope generators. In this case the break control will act like the sustain level. There are CV inputs for the attack, decay1, decay2 and release rates.<ref name="rh" />


The CV input for attack is inverted, so increasing the CV level will shorten the attack time while increasing the decay times for decay 1, decay 2, and release. This means that when MIDI velocity is used as a CV a higher velocity will shorten the attack and increase the other decay times.<ref name="rh" />
Most of Rob's module designs use SSM quad VCA chips, possibly the Analog Devices SSM2164 (?)


Rate settings can be from really snappy to pretty slow. Care was taken that you still have good control over the rates when in the snappy range.<ref name="rh" />


The ADBDR envelope is designed to finish its attack phase before it can be re-triggered. When used for sequencing this allows for complex envelope shapes producing interesting rhythmic effects, but when used for fast keyboard play it might feel a bit strange to play the module with long attack times.<ref name="rh" />
<b>OSC HRM</b><br>
Price 325 euro<br>
The Harmonic Oscillator module (OSC HRM) is used to create pitched waveforms with
dynamically controlled timbres. Pitch control law is 1V/Oct and the module uses a platinum
element for temperature stabilization of the pitch curve. Maximum frequency range is from
0.5 Hz to 16.000 Hz and the scale is perfectly tuned in the middle six octaves up to a pitch of
4.000 Hz. When playing pitches higher as 4000 Hz the 1V/Oct scale starts to break down, due
to the necessary internal bandlimiting in the harmonic generators.
The module uses a biquad sine/cosine oscillator at its core and through a process of recursion
harmonic series of overtones are generated. There are two recursion paths, one that produces
all harmonics and one that produces only the odd harmonics. By gradually opening the knobs
that control the amount of recursion more and more harmonics are generated. When only the
all harmonics path is used the waveform morphs smoothly from a sinewave to a waveform
that closely resembles and sounds like a sawtooth or an inverted sawtooth. Opening only the
odd harmonics knob will smoothly morph from a sinewave to a squarewave. When opening
both knobs effects like pulse wave modulation are possible. Building up these harmonic series
is under full voltage control and can be modulated from slow LFO speeds to fast audio rates
to create FM timbres. When the waveforms are modulated there is a negligable amount of
detune (less than 1 cent), though when modulating at audio rates an asymmetry in the
modulating waveform can cause detune effects on deep modulations.
There is an additional VCA incorporated in the module. The final output signal can be taken
from a point just before the VCA and at the output of the VCA. This enables the module to be
easily used in a situation where one wants to modulate another module by an audio rate signal
and have the modulation depth under voltage control using e.g. a LFO waveform, an envelope
voltage signal or a play controller that produces a control voltage, while still having the full
output level signal available on the full output to serve different purposes.
The waveforms have an exceptionally warm sound and when dynamically modulated have a
deep spatial and organic character.
With only one OSC HRM and one DUAL ENV module you can already have a voice with
dynamic timbral and volume control that can do e.g. a pretty solid bass line


Note that there are no attenuator knobs to set the amount of modulation for the ADBDR envelope CV inputs allowing for direct connection to velocity CV or CC#. However when modulated from other sources they might need extra CV processing to set the modulation levels properly.<ref name="rh" />
<b>Dual Phaser </b><br>
Price: 385 Euro.<br>


=== Gate or Trig Toggle ===
The internal CV voltage scale is 1V/Oct. Each phaser has a reasonably accurate one volt per octave direct control input that can track the keyboard voltage. Normalization is used, routing the V/Oct input signal of phaser1 into phaser2 when the phaser2 V/Oct input is left unplugged.
New versions of the module feature a toggle switch to select between GATE or TRIG modes. When using long pulses or 'gates' as inputs the envelope will pause at the break level while the gate is high, and continue when the gate is low. Toggle mode will simply run through all stages of the function without interruption. <!-- Need to clarify this with testing or Rob. -->


=== ENV B ===
Total control range is about 18 octaves. The Frq knob goes over the top 9 octaves of this range. Through the V/Oct and Modulation inputs you can go deeper, but you get into the LFO range and audible phasing effects would disappear.
The second envelope generator is intended as a modulation envelope generator to e.g. sweep a filter or control the harmonic wave shaping of an [[Rob Hordijk OSC HRM|OSC HRM]]. The range is from several milliseconds to about a minute.<ref name="rh" />


Earlier versions featured an extra output that is controlled by a bipolar mix knob that can invert the envelope shape and also gives some extra overall ‘sink’ or ‘lift’ when the output level is increased. Later versions traded this for a plain inverted output, and instead gave the envelope a second stage (attack), with a pot for control.
It is however possible to use the phasing effect on LFO control signals in the 1Hz to 10Hz range by supplying the V/Oct with e.g. a fixed -5V control signal, which can create quite interesting LFO effects on e.g. drones. All inputs and outputs are DC coupled, so CV signals can pass the module equally well as audio signals. Only the internal resonance is AC coupled, so resonance drops off below roughly 10Hz.


=== Sample & Hold ===
Additionally each phaser has a modulation input, also at 1V/Oct when the mode is set to sweep. When the mode is set to spread it behaves like the modulation sensitivity is halved, also when it is in half mode where only half of the poles in each phaser are modulated by this input. These inputs are not normalized, in fact if no plug is connected the modulation level knobs receive a fixed voltage so a manual spread value can be set.
When modulating decay times with control voltages it is good advise to keep the voltage fixed while the envelope is developing. For example trying to modulate the decay time with an audio rate signal does in general not produce sensible results. A S&H is integrated into the module to sample the decay time modulation input signal (S&H IN) on every new gate trigger. This way the modulation amount will stay fixed until the module is triggered again by a new gate pulse. The full sampled signal is sent straight to the S&H OUT, so it can be routed to an input of choice on ENV A or use elsewhere, but is attenuated using the ENV B MOD knob before being sent to the ENV B DECAY function.<ref name="rh" />
[[File:RobHordijk-OSCSYNC-DUALENV-TWINPEAK.jpg.jpg|thumb|A Rob Hordijk DUAL ENV filter (centre) in triple-module format with a TWIN PEAK (right) and OSC SYNC (left) - this version features a toggle switch for GATE or TRIG modes, and another for ENV B self-cycling mode.]]


=== Normalisations ===
Audio input is maximum 12V peak/peak before clipping occurs and there is 6dB attenuation from input to output to enable resonance peaks without clipping.
Many of Rob's designs feature internal connections or 'normalisations' between inputs and outputs. These can be broken by inserting jacks into the inputs. When found together in triple-module formation the following normalised connections were made:


* TRIPLE LF-VCO - B PULSE > DUAL ENV - GATE IN
Audio routing is as follows:
* DUAL ENV - ENV A OUT > TWINPEAK - VCA CV
If a jack is connected to input1, and if input2 is unconnected, then the audio will route into both phasers. In this mode you can use the two phaser outputs as a stereo signal. Connecting a jack to input2 will override this internal input1->input2 connection and separate both phasers.


== References ==
If audio is routed into input1 and if input2 is left unconnected, and if a jack is connected into ónly output2, then the two phasers are automatically set to "inverse parallel" mode. Meaning that if both phasers are set to exactly the same knob settings the phaser outputs would be in exact reverse phase and thus result in almost silence.
{{From Mod Wiggler Wiki|Rob Hordijk Designs}}
{{reflist}}


== External links ==
If audio is routed into input1, and if output1 is connected with a short cable to input2, and if output2 is taken as the overall output, the two phasers are in series and thus result in one 16-pole phaser.
* Rob Hordijk explains the [http://www.youtube.com/watch?v=Knbkv6OxcsE&list=PLAC347DE38ABA9E8D&index=4 Dual Envelope Generator] at the European Electro Music Event 2012, Mallorca, Spain.


[[Category:Original Rob Hordijk Design]]
To summarize: you can use the phasers fully separated, parallel with two (stereo) outputs on one input signal, parallel with mono output but with one phaser in reversed phase before the mixing of the outputs of the phasers take place on output2, or in series. All this is accomplished by the internal switches in the connectors and only depends on which inputs and outputs have a plug."
[[Category:5U modules]]




<b>Active Matrix</b><br>
Price: a little under 500 Euro.<br>
The Active Matrix module is buffered and works similar to the EMS Synthi.
It comes with mono plugs and some have built-in resistors for -6db or -12db signal reduction.
Every point is an insert, and with an insert cable, you can patch whatever you like into that point.

<b>Dual Envelope Generator</b><br>
Price 295 euro<br>
The Dual Envelope module (DUAL ENV) is a fully voltage controlled envelope generator
specifically designed to be used with sequenced music. There are two different types of
envelopes available, one is a four stage (attack, decay1, break level, decay2, release) envelope
and the second is a one stage envelope (decay only). Both envelope generators share the same
gate input, meaning that they can not be triggered separately. Triggering treshold is at roughly
100mV above ground and also accepts e.g. triangle waves.
The ADBDR envelope is primarily intended to be used for volume envelopes. When the
decay2 knob on the first envelope generator is fully open the decay2 acts like the sustain that
you find on most of the traditional envelope generators. In this case the break control will act
like the sustain level. There are CV inputs for the attack, decay1, decay2 and release rates.
The CV for the attack is inversed, so increasing the CV level will shorten the attack time
while increasing the decay times for the decay1, decay2 and release. This means that when
e.g. the key velocity voltage is used a higher velocity will shorten the attack and increase the
other decay times. Rate settings can be from really snappy to pretty slow. Care was taken that
you still have good control over the rates when in the snappy range.
The second envelope generator is intended as a modulation envelope generator to e.g. sweep a
filter or control the harmonic waveshaping of an OSC HRM module. It has an extra output
that is controlled by a bipolar mix knob that can invert the envelope shape and also gives
some extra overall ‘sink’ or ‘lift’ when the output level is increased. Rate can be set from a
glitch to about a minute.
When modulating decay times with control voltages it is good advise to keep the voltage fixed
while the envelope is developing. E.g. trying to modulate the decay time with an audio rate
signal does in general not produce sensible results. A S&H is integrated into the module to
sample the decaytime modulation input signal for the second envelope generator on every
new gate trigger. This way the modulation amount will stay fixed until the module is triggered
again by a new gate pulse. The sampled signal is also brought out on a connector, so it can be
routed to a CV input on the first ADBDR envelope generator. Or be used in any other S&H
application.
The ADBDR envelope is designed in a way that is hás to finish its attack phase to reach its
peak level before it can be retriggered. When used for sequencing this allows for complex
envelope shapes that give interesting rhythmic effects, but when used for keyboard play it
might feel a bit strange to play the module with long attack times and fast play.
Note that there are no attenuator knobs to set the amount of modulation for the ADBDR
envelope CV inputs, these inputs are at full sensitivity. They can be connected directly to e.g.
the velocity CV or CC# CV outputs of a MIDItoCV converter, but when modulated from
other sources one might need an extra CV mixer module to set the modulation levels properly

Latest revision as of 02:54, 20 June 2022

Panel design for an early Rob Hordijk DUAL ENV

The DUAL ENV is a module by Rob Hordijk. It features two paired envelopes with different shapes, ENV A is a four-stage (attack, decay 1, break level, decay 2, release) and ENV B a two-stage (attack, decay). It also features a Sample and Hold function. There have been a few versions with different envelope stages, toggle switches, and modulation possibilities.

Both envelope generators share the same gate input, meaning that they can not be triggered separately, though in later versions ENV B featured a toggle switch to allow self-cycling. This also features two LEDs to indicate the gate status of each envelope.

Triggering threshold is roughly 100mV above ground, and can be triggered by wave forms other than pulses, e.g. triangle waves.[1]

ENV A

A flow chart explaining the functionality of the DUAL ENV

The ADBDR envelope is primarily intended to be used for volume envelopes. When the decay2 knob on the first envelope generator is fully open the decay2 acts like the sustain that you find on most of the traditional envelope generators. In this case the break control will act like the sustain level. There are CV inputs for the attack, decay1, decay2 and release rates.[1]

The CV input for attack is inverted, so increasing the CV level will shorten the attack time while increasing the decay times for decay 1, decay 2, and release. This means that when MIDI velocity is used as a CV a higher velocity will shorten the attack and increase the other decay times.[1]

Rate settings can be from really snappy to pretty slow. Care was taken that you still have good control over the rates when in the snappy range.[1]

The ADBDR envelope is designed to finish its attack phase before it can be re-triggered. When used for sequencing this allows for complex envelope shapes producing interesting rhythmic effects, but when used for fast keyboard play it might feel a bit strange to play the module with long attack times.[1]

Note that there are no attenuator knobs to set the amount of modulation for the ADBDR envelope CV inputs allowing for direct connection to velocity CV or CC#. However when modulated from other sources they might need extra CV processing to set the modulation levels properly.[1]

Gate or Trig Toggle

New versions of the module feature a toggle switch to select between GATE or TRIG modes. When using long pulses or 'gates' as inputs the envelope will pause at the break level while the gate is high, and continue when the gate is low. Toggle mode will simply run through all stages of the function without interruption.

ENV B

The second envelope generator is intended as a modulation envelope generator to e.g. sweep a filter or control the harmonic wave shaping of an OSC HRM. The range is from several milliseconds to about a minute.[1]

Earlier versions featured an extra output that is controlled by a bipolar mix knob that can invert the envelope shape and also gives some extra overall ‘sink’ or ‘lift’ when the output level is increased. Later versions traded this for a plain inverted output, and instead gave the envelope a second stage (attack), with a pot for control.

Sample & Hold

When modulating decay times with control voltages it is good advise to keep the voltage fixed while the envelope is developing. For example trying to modulate the decay time with an audio rate signal does in general not produce sensible results. A S&H is integrated into the module to sample the decay time modulation input signal (S&H IN) on every new gate trigger. This way the modulation amount will stay fixed until the module is triggered again by a new gate pulse. The full sampled signal is sent straight to the S&H OUT, so it can be routed to an input of choice on ENV A or use elsewhere, but is attenuated using the ENV B MOD knob before being sent to the ENV B DECAY function.[1]

A Rob Hordijk DUAL ENV filter (centre) in triple-module format with a TWIN PEAK (right) and OSC SYNC (left) - this version features a toggle switch for GATE or TRIG modes, and another for ENV B self-cycling mode.

Normalisations

Many of Rob's designs feature internal connections or 'normalisations' between inputs and outputs. These can be broken by inserting jacks into the inputs. When found together in triple-module formation the following normalised connections were made:

  • TRIPLE LF-VCO - B PULSE > DUAL ENV - GATE IN
  • DUAL ENV - ENV A OUT > TWINPEAK - VCA CV

References

This page uses Creative Commons Licensed content from Mod Wiggler Wiki:Rob Hordijk Designs (View authors).

  1. ^ a b c d e f g h Rob Hordijk

External links

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