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11

Resonance

Q:

 The 

Q

 knob determines the level of feedback from the filter’s output 

to its input.

• 

This is also known as the 

Resonance

Emphasis

, or 

Feedback

.

• 

With resonance introduced, the cutoff frequency of the low pass and 
high pass filters accentuate while the centre frequency of the band 
pass and notch filters inversely scales in amplitude.

• 

Turning the knob clockwise will increase resonance.

• 

Turning the knob anticlockwise will decrease resonance.

Q CV Input:

 The 

Q CV Input

 is a bipolar control voltage input for 

Q

.

• 

Control voltage is summed with the knob position.

• 

Input range: -/+ 8V.

Feedback Toggle:

 The 

Feedback Toggle

 enables and disables internal 

routing of the 

Band Pass Output

 to 

I-ō47

 input. When enabled, 

increasing 

Q

 can result in self-oscillation.

• 

If the toggle is in the up position, feedback is enabled.

• 

If the toggle is in the down position, feedback is disabled.

• 

If the 

Q

 knob is at its maximum value and there is no input signal, 

I-ō47

 will self-oscillate as a stable sine waveform.

Strike Input:

 Rising edge signals present at the 

Strike Input

 excite the 

resonance of 

I-ō47

.

• 

Gate and trigger signals present at the 

Strike Input

 will ping  

the resonance.

• 

Audio rate waveforms present at the 

Strike Input

 result effects similar 

to hard synchronisation. 

• 

It’s important to note that the 

Strike Input

 is not a low pass gate input 

and will not affect the cutoff frequency. Only the resonance  
is affected. 

Summary of Contents for I-o47

Page 1: ...I 47 Multimode Resonator Filter User Manual...

Page 2: ...Features 4 Installation Specifications 5 Overview 6 Input Output 8 Frequency Modulation 1 1 Resonance 12 Patch Examples East Coast Synth Voice Sine Wave Generator Set Phaser To Stun Kick Drum Kick Dr...

Page 3: ...uirks A hybrid design of matched transistor pairs and precision op amps was used to create the circuit s semi discrete VCAs making the I 47 a beast of its own variety With on board limiter waveshaper...

Page 4: ...r cable is connected to 12V 4 Connect the 16 pin side of the IDC power cable to the 2x8 pin header on your Eurorack power supply confirming that the red stripe on the power cable is connected to 12V 5...

Page 5: ...s of a classic multimode filter resonator Key 1 Input 2 Limiter Toggle 3 Gain 4 Inverting Input 5 Low Pass Output 6 Band Pass Output 7 High Pass Output 8 Notch Output 9 Course 10 Fine 1 1 FM Input 12...

Page 6: ...full scale amplitude If the fader is in the down position the signal present at the Input will be fully attenuated If limiting is enabled the centre position of the Gain fader is optimised as a sweet...

Page 7: ...ntre frequency are attenuated High Pass Output High pass filter output Any harmonics below the cutoff frequency are attenuated Notch Output Notch filter output This is also known as a Band Stop Filter...

Page 8: ...6Hz 16KHz Fine The Fine knob is used for minute control of the cutoff frequency of the low pass and high pass filters and the centre frequency of the band pass and notch filters Fine tuning is relativ...

Page 9: ...ct Input can be used for consistent pitch tracking of the sine waveform effectively making I 47 a quadrature sine waveform oscillator Control voltage is summed with the level set by the Coarse and Fin...

Page 10: ...s Output anti clockwise or the High Pass Output clockwise Notch CV Input The Notch CV Input is a bipolar control voltage input for the Notch parameter Signal present at the Notch CV Input will affect...

Page 11: ...The Feedback Toggle enables and disables internal routing of the Band Pass Output to I 47 input When enabled increasing Q can result in self oscillation If the toggle is in the up position feedback i...

Page 12: ...pass through More traditional East Coast patches would incorporate separate envelope generators for I 47 and the VCA Audio Path Connect the desired waveform of an oscillator to the Input of I 47 Conn...

Page 13: ...ws I 47 to track the sequencer or keyboard voltage As higher voltages are generated the cutoff frequency increases Connect the gate output of the sequencer or keyboard to the trigger input of an envel...

Page 14: ...not needed because a sine waveform only loses amplitude when patched through a filter This is because there are no other harmonics to attenuate only the fundamental Audio Path Connect the Low Pass Ou...

Page 15: ...put of I 47 Connect the gate output of the sequencer or keyboard to the trigger input of an envelope generator Connect the envelope generator CV output to the CV input of the VCA and set the correspon...

Page 16: ...e used to reset the cycle of the LFOs LFOs can be free running or in synchronized patterns such as fixed quadrature phase shifted or multiplied divided Audio Path Connect the desired waveform of an os...

Page 17: ...Fine knobs to desired positions Set the Q knob to a desired position Set the Notch knob to 1 its centre position Set the level of both channels of the mixer to be equal Control Path Connect a bipolar...

Page 18: ...Band Pass Output Set the fundamental frequency of the kick drum sound using the Coarse and Fine knobs Disable feedback by setting the Feedback Toggle to its down position Set the Q knob to a desired p...

Page 19: ...set the FM Attenuverter just to the right of its centre position This sets the amount of pitch modulation for the kick drum sound Set the shape knob of c is to a logarithmic exponential response curve...

Page 20: ...g between the oscillator and silence Audio Path Connect a square waveform of an oscillator to the Inverting Input of I 47 Monitor the Low Pass Output Set the fundamental frequency of the oscillator to...

Page 21: ...c is to the Strike Input Connect the CV output of c is to a multiple Connect one copy of the c is CV signal to the FM Input and set the FM Attenuverter just to the right of its centre position This se...

Page 22: ...waveform LFO modulates I 47 while a sub square waveform from C L pings the resonance of I 47 The sequencer sends voltages to the 1V OCT of the I 47 while simultaneously triggering c is The CV output...

Page 23: ...ntrol Path Connect the 1V Oct output of a sequencer to the 1V Oct input of I 47 Connect the gate output of the sequencer to the gate trig input of c is Connect the CV output of c is to the CV input of...

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