Rob Hordijk Active Matrix: Difference between revisions
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[[File:Hordijk am.png|thumb|right|200px]]The 4U [[MU]] or 5U [[MOTM]] '''Rob Hordijk Active Matrix''' module is a fully buffered eight by eight matrix where any one of eight input signals can be added to any one of eight outputs. By using ¼-inch tip-ring-sleeve insert jacks for the matrix nodes (equal to stereo jacks) a whole range of applications ecome possible. First the column input signal is buffered and then routed to the tips of the nodes in that column. The ring signals of the nodes are basically summing inputs and summed to the final output signals at the ends of the rows. By connecting a stereo jack where the tip and the ring are connected directly together, a connection with unity gain is made from a column input to a row output. If the tip-ring connection in the jack goes through a resistor an additional attenuation can be accomplished. E.g. a 30k resistor will attenuate by 6 dB and a 91k resistor by 12 dB.<ref name="rh">Rob Hordijk</ref> |
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Contact Rob directly for details about his modules: rhordijk@xs4all.nl. <br> |
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[[File:Hordijk mb.png|thumb|right|200px]]When a stereo audio cable is soldered to a jack plug and on the other side of the cable a potentiometer is attached the potentiometer will act like a pot on the node, enabling to set the mix level by the pot. Basically each node is an insert, just like the inserts on a mixing desk. And can thus be used in the same way. So, using a jack with a pot means to ‘insert’ the pot into the signal path. This means that you can insert any other outside world device in the signal path by using an insert cable with a stereo jack on one side and two mono jacks on the other, provided signal levels match of course (e.g. 5V pp oscillator output signals will severely overload line level inputs on e.g. a digital effects rack or the guitar input of a stompbox). One could also connect a resistive sensor like a light dependent resistor (LDR) to a jack and make the node light sensitive.<ref name="rh" /> |
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Each column also acts like a multiple. When a mono jack is connected into a node it will pick up the column input signal from the tip. But the ring input is now short circuited to the ground through the sleeve of the mono jack and will so disable any input from this particular node to the row output. This will not interfere with any other nodes in the same column or row, because of the full buffering of both the column inputs and row outputs. So, any node that is not used to route a signal to a row output can be used as a multiple output. Meaning that the matrix is also eight multiples with one buffered input and eight buffered outputs on each multiple.<ref name="rh" /> |
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Rob also has a subforum at the Electro-Music forum site: |
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http://electro-music.com/forum/index.php?f=185 |
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Matrices with bigger sizes can be built on demand. Input columns come in multiples of eight and any number of output rows are possible.<ref name="rh" /> |
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== Mini Bay == |
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Most of Rob's module designs use SSM quad VCA chips, possibly the Analog Devices SSM2164 (?) |
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The 2U wide MiniBay is a smaller version of the Active Matrix. It has a four input by six output fully buffered matrix plus two passive multiples with five jacks each. The matrix section works exactly like the 8x8 Active Matrix.<ref name="rh" /> |
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== Mini Mix == |
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Mini Mix is a mixer module to turn patch points into mixers like a matrix mixer.<ref>Mod Wiggler forum:[https://www.modwiggler.com/forum/viewtopic.php?t=32246&start=all&postdays=0&postorder=asc Rob Hordijk Phaser Filter demos]</ref> |
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== References == |
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<b>OSC HRM</b><br> |
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{{From Mod Wiggler Wiki|Rob Hordijk Designs}} |
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Price 325 euro<br> |
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{{reflist}} |
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The Harmonic Oscillator module (OSC HRM) is used to create pitched waveforms with |
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dynamically controlled timbres. Pitch control law is 1V/Oct and the module uses a platinum |
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element for temperature stabilization of the pitch curve. Maximum frequency range is from |
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0.5 Hz to 16.000 Hz and the scale is perfectly tuned in the middle six octaves up to a pitch of |
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4.000 Hz. When playing pitches higher as 4000 Hz the 1V/Oct scale starts to break down, due |
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to the necessary internal bandlimiting in the harmonic generators. |
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The module uses a biquad sine/cosine oscillator at its core and through a process of recursion |
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harmonic series of overtones are generated. There are two recursion paths, one that produces |
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all harmonics and one that produces only the odd harmonics. By gradually opening the knobs |
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that control the amount of recursion more and more harmonics are generated. When only the |
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all harmonics path is used the waveform morphs smoothly from a sinewave to a waveform |
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that closely resembles and sounds like a sawtooth or an inverted sawtooth. Opening only the |
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odd harmonics knob will smoothly morph from a sinewave to a squarewave. When opening |
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both knobs effects like pulse wave modulation are possible. Building up these harmonic series |
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is under full voltage control and can be modulated from slow LFO speeds to fast audio rates |
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to create FM timbres. When the waveforms are modulated there is a negligable amount of |
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detune (less than 1 cent), though when modulating at audio rates an asymmetry in the |
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modulating waveform can cause detune effects on deep modulations. |
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There is an additional VCA incorporated in the module. The final output signal can be taken |
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from a point just before the VCA and at the output of the VCA. This enables the module to be |
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easily used in a situation where one wants to modulate another module by an audio rate signal |
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and have the modulation depth under voltage control using e.g. a LFO waveform, an envelope |
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voltage signal or a play controller that produces a control voltage, while still having the full |
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output level signal available on the full output to serve different purposes. |
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The waveforms have an exceptionally warm sound and when dynamically modulated have a |
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deep spatial and organic character. |
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With only one OSC HRM and one DUAL ENV module you can already have a voice with |
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dynamic timbral and volume control that can do e.g. a pretty solid bass line |
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== External links == |
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<b>Dual Phaser </b><br> |
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* Rob Hordijk explains the [https://www.youtube.com/watch?v=kSKp2q3LlUE&index=6&list=PLAC347DE38ABA9E8D Active Matrix] at the European Electro Music Event 2012, Mallorca, Spain. |
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Price: 385 Euro.<br> |
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[[Category:Original Rob Hordijk Design]] |
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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. |
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[[Category:5U modules]] |
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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. |
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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. |
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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. |
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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. |
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Audio routing is as follows: |
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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. |
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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. |
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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. |
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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." |
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<b>Active Matrix</b><br> |
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Price: a little under 500 Euro.<br> |
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The Active Matrix module is buffered and works similar to the EMS Synthi. |
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It comes with mono plugs and some have built-in resistors for -6db or -12db signal reduction. |
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Every point is an insert, and with an insert cable, you can patch whatever you like into that point. |
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<b>Dual Envelope Generator</b> |
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Latest revision as of 18:09, 24 April 2021
The 4U MU or 5U MOTM Rob Hordijk Active Matrix module is a fully buffered eight by eight matrix where any one of eight input signals can be added to any one of eight outputs. By using ¼-inch tip-ring-sleeve insert jacks for the matrix nodes (equal to stereo jacks) a whole range of applications ecome possible. First the column input signal is buffered and then routed to the tips of the nodes in that column. The ring signals of the nodes are basically summing inputs and summed to the final output signals at the ends of the rows. By connecting a stereo jack where the tip and the ring are connected directly together, a connection with unity gain is made from a column input to a row output. If the tip-ring connection in the jack goes through a resistor an additional attenuation can be accomplished. E.g. a 30k resistor will attenuate by 6 dB and a 91k resistor by 12 dB.[1]
When a stereo audio cable is soldered to a jack plug and on the other side of the cable a potentiometer is attached the potentiometer will act like a pot on the node, enabling to set the mix level by the pot. Basically each node is an insert, just like the inserts on a mixing desk. And can thus be used in the same way. So, using a jack with a pot means to ‘insert’ the pot into the signal path. This means that you can insert any other outside world device in the signal path by using an insert cable with a stereo jack on one side and two mono jacks on the other, provided signal levels match of course (e.g. 5V pp oscillator output signals will severely overload line level inputs on e.g. a digital effects rack or the guitar input of a stompbox). One could also connect a resistive sensor like a light dependent resistor (LDR) to a jack and make the node light sensitive.[1]
Each column also acts like a multiple. When a mono jack is connected into a node it will pick up the column input signal from the tip. But the ring input is now short circuited to the ground through the sleeve of the mono jack and will so disable any input from this particular node to the row output. This will not interfere with any other nodes in the same column or row, because of the full buffering of both the column inputs and row outputs. So, any node that is not used to route a signal to a row output can be used as a multiple output. Meaning that the matrix is also eight multiples with one buffered input and eight buffered outputs on each multiple.[1]
Matrices with bigger sizes can be built on demand. Input columns come in multiples of eight and any number of output rows are possible.[1]
Mini Bay
The 2U wide MiniBay is a smaller version of the Active Matrix. It has a four input by six output fully buffered matrix plus two passive multiples with five jacks each. The matrix section works exactly like the 8x8 Active Matrix.[1]
Mini Mix
Mini Mix is a mixer module to turn patch points into mixers like a matrix mixer.[2]
References
This page uses Creative Commons Licensed content from Mod Wiggler Wiki:Rob Hordijk Designs (View authors).
External links
- Rob Hordijk explains the Active Matrix at the European Electro Music Event 2012, Mallorca, Spain.