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Audiospektri HG-30 Instructions For Use Manual

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®
HG-30

Instructions for use

®
Our HG-30
synthesizer gets its name from its principal function where 30 harmonic frequencies are generated atop
the base note. However, it has a total of 14 different modes of operation, mostly using additive synthesis, but some
modes also apply filtering operations for subtractive synthesis. Additionally, four different variations of the classical
channel vocoder are included. HG-30 follows the Eurorack compatible modular synthesizer standard and is not a
stand-alone module, but requires external power from the rack, note determining external voltage, and preferably
several external envelope generators. These instructions cover the power requirements, external connections,
common operating characteristics, and then instructions for each of the 14 synthesis modes. These instructions are
quite detailed, and for experienced users, there is a more compact section at the end for quick setup of different
operating modes, see "Quick mode setup".
Audiospektri Finland Oy 2018. Rev 2.0
©
HG-30 is a registered trademark of Audiospektri Finland Oy,
www.audiospektri.com
Lindforsinkatu 19A26, 33720 Tampere, Finland
1

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  • Page 1: Instructions For Use

    Additionally, four different variations of the classical channel vocoder are included. HG-30 follows the Eurorack compatible modular synthesizer standard and is not a stand-alone module, but requires external power from the rack, note determining external voltage, and preferably several external envelope generators.

  • Page 2: Table Of Contents

    Table of Contents HG-30® Instructions for use......................1 Power requirements........................3 Dimensions..........................3 Front panel texts.........................4 External connections and additional required modules not included ........5 Connections and controls in detail....................6 List of Operating modes......................7 Virtual switchboard........................8 Slider calibration.........................9 Tuning............................9 Grounding, shielding and RF interference................10 Operating modes in detail......................11...

  • Page 3: Power Requirements

    Dimensions The HG-30 front panel dimensions are 162.5mm x 128.4 mm, so it occupies 32 HP units horizontally. The depth is 25.0 mm from the front panel bottom level, and from that level the highest knob extends 19.5mm upwards.

  • Page 4: Front Panel Texts

    Figure 1: The HG-30 front panel texts and outlines. Front panel texts The front panel texts are shown in the picture. To make it easier to find the controls in these instructions, all the words that can be found on the front panel of the synthesizer are emphasized in bold throughout the whole text.

  • Page 5: External Connections And Additional Required Modules Not Included

    7 cannot be used for other input voltages. The MIDI modules typically also have pitch bend and key velocity control outputs. These can be connected to the corresponding HG-30 front panel jacks labeled CV pitch and CV velocity, correspondingly.

  • Page 6: Connections And Controls In Detail

    Their input impedance is 10 000 Ohms, therefore a typical envelope generator can easily drive several inputs simultaneously. Mainly for testing purposes, HG-30 has one constant voltage output labeled D.C. out that can be connected to the envelope or modulation inputs.

  • Page 7: List Of Operating Modes

    List of Operating modes The HG-30 has 14 different operating modes, selectable by rotating the mode select knob. The mode selector only has 10 positions, therefore modes over 9 are indicated by the light emitting diode to the left of the selector.

  • Page 8: Virtual Switchboard

    Virtual switchboard A key characteristic of the HG-30 is the employment of a virtual switchboard that allows any of the eight envelope inputs to be routed to any of the 30 slide potentiometers which then will scale the external envelope signals connected by typical patch cables from external envelope generators.

  • Page 9: Slider Calibration

    Tuning HG-30 uses a precision 12 bit A/D converter to convert the VC note signal from the bus to the note value. Therefore it stays well in tune, and normally tuning is not needed. However, if the input VC note value is inaccurate, HG-30 has means for compensating for the inaccuracies.

  • Page 10: Grounding, Shielding And Rf Interference

    However, in a case when signals from a remote rack are connected to the HG-30 inputs, large ground loops may be created. The unwanted additional ground usually comes from a common power jack safety ground connection, so the obvious remedy is to use systems with fully isolated power supplies.

  • Page 11: Operating Modes In Detail

    Operating modes in detail Mode 0: 30 harmonics, global noise and phase modulation The first operating mode generates 30 harmonic frequencies with individual envelope control for each using the corresponding 30 sliders. In addition to the nominal amplitude set by the sliders, each harmonic can be dynamically modulated by an external envelope generator output when connected to one of the 8 envelope inputs.

  • Page 12: Mode 1: 15 Harmonics, Individual Noise And Phase Modulation

    Mode 1: 15 harmonics, individual noise and phase modulation Mode 1 is similar to Mode 0, with the following exceptions: – only 15 harmonics are generated – the noise and/or PM modulation strength for each of the 15 harmonics can individually be adjusted using the corresponding sliders 16 - 30, i.e.

  • Page 13: Mode 2: Comb Filtered Pseudoperiodic Signal

    Mode 2: Comb filtered pseudoperiodic signal Mode 2 uses a white noise source as an input to a comb filter, thereby creating a pseudoperiodic harmonic signal. The speed of the filter is adjusted using the input note control voltage, therefore the apparent pitch of the pseudoperiodic signal follows the same calibrated note pitch as the other modes.

  • Page 14: Mode 3: Base Note With Selectable Intervals

    Mode 3: Base note with selectable intervals This mode can generate the whole set of musical intervals within one octave, i.e. maximum of 7 notes. Each note then can have a maximum of 15 harmonics. The first 15 sliders are used in the same way as in the basic form for controlling the corresponding harmonic amplitudes.

  • Page 15: Mode 4: Pseudo-Vcf With Noise Control

    Mode 4: Pseudo-VCF with noise control Mode 13: Pseudo-VCF with PM control Although this mode uses additive synthesis, it is still possible to do signal processing that closely resembles voltage controlled filter (VCF) operation. In vintage analog synthesizers VCF was one of the main attractions. In this mode, the harmonic generator makes 15 harmonics that are fed to a spectrum shaper.
  • Page 16 the PM are not filtered out based on their own frequency, but instead based on the frequency of the fundamental that was modulated. As an example, if you have a harmonic at a frequency of 550Hz, then its amplitude is determined by Slider 18 (provided no modulation is controlling VCF at modulation 2 or adjust 2 is at its reset position).

  • Page 17: Also The Possibility To Generate Non-Harmonic Overtones

    Mode 5: True chorus with 10 chorus members, each having a maximum of 19 harmonics. Also the possibility to generate non- harmonic overtones. Mode 5 generates 10 different fundamental frequencies, each with a maximum of 19 harmonics. The fundamental frequencies are generated close to each other, therefore making a true chorus of 10 members ("true" used here to emphasize the difference from typical chorus effects that loop the same voice to create a similar effect).
  • Page 18 Figure 3: Mode 5 sample spectrum. Only three harmonic sliders were used to adjust different amplitudes for the fundamental (at 500Hz), the 5 and the 10 harmonics. All the 10 chorus members are activated using sliders 21 - 30, using amplitudes decreasing when going outwards from the nominal note frequency. The deviation of the chorus members is adjusted to the maximum, so that especially the higher harmonic spectra can clearly be seen to contain 10 separate frequencies.

  • Page 19: Mode 10: 30 Harmonics With Two Parameter Noise Control

    Mode 10: 30 harmonics with two parameter noise control This mode is similar to Mode 0, with the following exceptions: – No phase modulation. – modulation 2 is used for modulating the setting of adjust 2 (see its description below; modulation 1 still controls the noise amplitude).

  • Page 20: Mode 12: Harmonic Generator With Built-In Sequenced Envelope Generator

    Mode 12: Harmonic generator with built-in sequenced envelope generator This mode can generate a signal with 29 harmonic frequencies. Instead of the external envelope generator inputs, an internal one is used, and its output is fed to a virtual delay line so that a maximum of 8 delayed envelope waveforms can be used for modulating the harmonics.
  • Page 21 As a summary, here is a list of controls and the patch cable connections required for Mode 12: 1. The external envelope generator inputs 1 - 8 need not to be connected (if you have cables already connected to them, no harm, you can keep them connected, but they have no effect). 2.

  • Page 22: Mode 14: Frequency Modulated Harmonic Generator

    Mode 14: Frequency modulated harmonic generator As was explained in the section ”PM vs FM”, frequency modulation of the harmonic generator signal will create also nonharmonic components that are especially useful for generating percussion-type sounds. In this mode, the maximum number of base note harmonics is 10. The harmonic amplitudes can be controlled in the typical way using sliders 1 –...
  • Page 23 The range of modulating signal frequencies is very wide, therefore this mode can be used all the way from slow vibrato/pitch bend -type of effects up to high frequency modulation that makes sidelobes far from each of the modulated base frequency spectral components. Both the modulating signal amplitude and frequency can be varied. The modulating signal frequency can be adjusted using adjust 1 and adjust 2 and modulated using an envelope output connected to modulation 1.
  • Page 24 can be heard from the frequency shift pattern. Then adding more sliders makes the shift pattern even more complex. Because the phase shift between the harmonics has a crucial effect on the shape of the combined modulation curve, the relative shift between successive harmonics has been made to change based on the number of the highest harmonic.

  • Page 25: Mode 6: Single Channel Vocoder

    Mode 6: Single channel vocoder Quick start guide for the connections: Inputs signals: mic: Microphone input, balanced 3.5mm TRS plug modulation 1: No function modulation 2: No function envelope inputs: envelope 1: Amplitude modulation envelope 2: No function envelope 3: Spectral shift modulation envelope 4: No function envelope 5: Noise modulation envelope 7: optional CV note input if the PCB switch is closed...
  • Page 26 slider defines the interpolation, lower ones do not have meaning if a higher one is up from the off position. Slider 11 activates the steepest, almost brick-wall interpolation. Sliders 29 and 30: Microphone digitizer noise gate. In addition to the spectral noise gate adjustment with Slider 6, also the input microphone A/D has noise gating.
  • Page 27 Other tips for more natural voice is to add some noise to the output using Sliders 2,3,4, and 5. Because natural voices typically have more noise at the higher frequencies, try to use 5 highest, and then successively lower settings for the rest.

  • Page 28: Mode 7: Single Channel Freeze Spectrum/Capture Transient Vocoder

    Mode 7: Single channel freeze spectrum/capture transient vocoder The vocoder makes it possible to build a spectrum with even more than 30 harmonic frequencies using a proper input signal to the microphone (i.e. also other than human voices). Mode 7 has been added in order to be able to fix a desired spectrum using the frequency analysis filter bank of the vocoder.
  • Page 29 overload led blinks when either the maximum or minimum is reached. The rotated angle is irrelevant, always the next transient in list is found for one key activation. When you have found a suitable one, keep slider 1 up, disconnect envelope input 8 and play the sample. Now adjust 1 comes back to its default function, i.e.

  • Page 30: Mode 8: Two Channel Vocoder

    Tip: When the stored transients are played back in slow speed (Slider 12 off and Slider 13 up), the time domain envelope has stepwise shape. If this becomes audibly irritating, adjusting Slider 7 downwards will filter the signal to remove the steps. Normally Slider 7 would best be fully up to retain the fast time response of the vocoder. Mode 8: Two channel vocoder Mode 8 controls are similar to Mode 6 controls, but because it adds a second voice to the synthesis part, it has a second set of controls for several functions.
  • Page 31 typically can be kept at maximum for rapid response. Slider 8: Spectral shaping; exaggerates the differences of spectral peaks and valleys when shifted upwards from the default off-position. Sliders 9 - 11: Control of the interpolation between the analyzed spectral bands. These are all on-off controls and their change only comes into effect after system reset or mode change.

  • Page 32: Mode 9: Two Channel Freeze Spectrum/Capture Transient Vocoder

    Mode 9: Two channel freeze spectrum/capture transient vocoder Mode 9 is similar to Mode 7 for the dual channel vocoder case, so please follow its instructions for use of Slider 1, Slider 12, Slider 13, envelope input 8, and the toggle switch, and otherwise follow Mode 8 instructions.

  • Page 33: Quick Mode Setup

    Quick mode setup Mode connections and adjustments are listed shortly for each mode in the following. For more detailed instructions, please read the longer mode sections. Also note that instead of the proposed external envelope generator outputs below, the D.C.out voltage from the front panel plug can be connected to all the envelope inputs, if you just want to keep the corresponding control voltage constant.
  • Page 34 Mode 3, 7 intervals x 15 harmonics 1. Connect envelope generator outputs to all those of the envelope inputs that you have selected for the desired sliders using the virtual switchboard. Note that both the 15 harmonics (sliders 1 to 15) and the 7 interval amplitude responses (sliders 16 to 22) can be modulated.
  • Page 35 Mode 10, 30 harmonics with two parameter noise control , Mode 11: 15 harmonics with individual two parameter noise control. 1. Connect envelope generator outputs to all those of the envelope inputs that you have activated for the desired harmonic sliders. 2.

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