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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

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Содержание HG-30

Страница 1: ...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...

Страница 2: ...de 3 Base note with selectable intervals 14 Mode 4 Pseudo VCF with noise control 15 Mode 13 Pseudo VCF with PM control 15 Mode 5 True chorus with 10 chorus members each having a maximum of 19 harmonics Also the possibility to generate non harmonic overtones 17 Mode 10 30 harmonics with two parameter noise control 19 Mode 11 15 harmonics with individual two parameter noise control 19 Mode 12 Harmon...

Страница 3: ... line that is the bottom terminal in the bus connector The 5V in the bus is not a standard feature in many racks so please check that your rack has this option installed The system diagnostics is run at power up and to show that everything is ok the two red leds one right to the volume knob and the other left to the mode select knob will blink successively and then both should go off Dimensions Th...

Страница 4: ...eded for user adjustment volume main volume adjustment adjust 1 and adjust 2 mode specific adjustments multi turn digital encoders D C out constant voltage output useful in many modes as a constant envelope output 8 x envelope inputs inputs for external envelope control can be routed to any of the 30 sliders for dynamic parameter control using the virtual switchboard positive voltage ranges CV pit...

Страница 5: ...CB switch The switch can be found through an opening in the metal grid a single horizontally operated switch If the switch is closed then envelope 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 HG 30 require...

Страница 6: ... 2 are multiturn rotary knobs that have control functions specific to each operating mode Three position toggle switch gate on off envelope select The HG 30 assumes that the modular synthesizer gate signal is connected through the rack bus In typical Eurorack systems the gate signal controls note activation and e g external envelope triggering However because the HG 30 relies on external envelopes...

Страница 7: ...with individual envelope control for each common modulatable PM synthesis and phase noise for each harmonic Mode 1 15 harmonics with individual envelope control for each and individual modulation depth control noise and or PM for each using the remaining 15 sliders Mode 2 Harmonic filtered noise bands from a voltage controlled comb filter with individual envelope control for each Mode 3 Base note ...

Страница 8: ...sition of the toggle switch any number of slider connections can be reprogrammed without the need to toggle the switch back and forth between single slider programming events Note that only the last moved slider is activated therefore if you accidentally move more than one slider at the same time you need to check back that all channels are in the desired order If you leave the moved slider at the...

Страница 9: ...a trimmer for fine adjustment for compensating possible input scale error This is typically sufficient for normal situations If not there is a software facility for adjusting both the offset and scaling errors Errors can also occur in the pitch bend signal CV pitch input so they can also be compensated in software This is described in the following Software tuning For software tuning turn the mode...

Страница 10: ...te signal ground so if there are noise problems use the receiving amplifier ground lift switches Or if there are none you can even disconnect the signal cable shield from the ground but only at the output side RF EM Interference The HG_30 has high speed digital circuitry therefore special concern has been paid to prevent high frequency emission to sensitive analog circuitry inside the same rack or...

Страница 11: ...rposes The other inputs CV pitch and CV velocity are used in the typical way i e the former for pitch bending and latter for key velocity based amplitude control These signals are available from typical MIDI input modules not included Note that adding simultaneously both noise and PM is also possible However in that case also some constant band low frequency noise will be added in addition to the ...

Страница 12: ...be used for weighting the input fed to modulation1 modulation 2 Figure 2 A spectrum created in Mode 1 with fundamental frequency at 500Hz and varied amplitudes set for harmonics 1 15 using corresponding sliders Only one of the sliders 16 30 is raised 25 10 therefore the noise adjustment using adjust 1 has created band limited noise only at the frequency of the corresponding harmonic i e number 10 ...

Страница 13: ...w noise is slow because the comb filter stabilization takes some time while moving in the opposite direction the rate is fast modulation 2 has no effect in this mode and sliders 19 29 should be kept off Furthermore the Eurorack gate signal is not used in this mode even if the toggle switch is in the on position Therefore the output level is all the time controlled by the external envelope inputs l...

Страница 14: ...s or even make a transition from one chord to another during the activation of a single base note In the case of rapidly varying envelopes such activation would be quite tricky to achieve manually with a normal polyphonic keyboard The sound samples include an arpeggio type pair where the first sample has the intervals modulated with increasing envelope amplitudes towards the higher notes and simul...

Страница 15: ...odulation voltage As usual you can alternatively connect the D C out voltage to modulation 2 and use adjust 2 to shift the pseudofilter bands to fixed lower or higher frequencies Frequency shifting in response to the modulation is equal to all the pseudofilter bands Note that when compared to real filters the time domain responses of the pseudofilters do not have relation to the filter steepness T...

Страница 16: ... the folded spectral components do not follow the harmonic relation If you want to avoid aliasing then attenuate the higher spectra using Slider 30 and possibly also Slider 29 or rotate adjust 1 less or use modulation only to the low frequency harmonics As a summary here is a list of the patch cable connections and adjustments 1 Connect envelope generator outputs to all those of the envelope input...

Страница 17: ...rate voices that resemble natural non harmonic voices like bells or drums with proper envelope shaping of amplitudes The adjustment using adjust 2 advances stepwise generating audible clicks therefore not useful during playing live A drawback from the true chorus operation is that such close frequencies inevitably will interfere i e make beating effects with their periods varying inversely proport...

Страница 18: ...s 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 Close to the fundamental the relative differences are the same as in the higher harmonics but due to the linear frequency scale the differences are...

Страница 19: ...ndom frequency hopping of the harmonics rather than noise The hopping period is increased with increased CW turning of adjust 2 so the signal spends more time at the random frequencies Notice that the range of adjust 2 is several tens of full rotations so you can hear the frequency hopping slowly slow down when you turn it CW Again it is convenient to connect modulation 1 to the D C out terminal f...

Страница 20: ...trigger is different For all the 29 harmonics corresponding to the sliders any of the 8 differently delayed identical waveforms can be selected The selection is done exactly in the same way as selecting one of the external envelope inputs in the basic mode i e by turning the toggle switch down to the position envelope select and then moving the selected slider up and down until one of the lit leds...

Страница 21: ...envelope shapes 4 Optionally connect the CV pitch and CV velocity inputs to the corresponding MIDI input module outputs 5 Keep the toggle switch in the gate on position If your MIDI interface module does not have the gate signal connected to the Eurorack bus use modulation 1 as the trigger input 6 Check the harmonic slider virtual link connections to the envelope inputs 1 8 because they determine ...

Страница 22: ...and 11 20 raised at least one of 21 28 raised and live envelopes or D C Out connected to modulation 1 2 and to all the envelope inputs that you have linked to the activated sliders In this mode the modulating signal is not added raw to the note determining voltage in the same way as the typical pitch bending signal of a keyboard would do Instead each of the 10 harmonics are separately frequency mo...

Страница 23: ...lation amplitude Figure 5 shows the situation when pairs of 3 13 and 10 20 are high while 6 is high but 16 off The chain of possible modulation amplitude controls may appear overly complex but it allows dynamic control of all the signal aspects 1 Global modulation amplitude through modulation 2 2 Individual modulating signal harmonic amplitude modulation through the virtual switchboard inputs link...

Страница 24: ...ghtforward FM can be created by feeding external modulation to the pitch bend input CV pitch because it also has a wide bandwidth but then the spectral spreading of each harmonic is proportional to the harmonic number As a summary here is a list of the patch cable connections required for mode 14 1 Connect envelope generator outputs to all those of the envelope inputs that you have activated for t...

Страница 25: ...fundamental Note that envelope 5 modulation only works in the manual mode Slider 3 Corresponding noise adjustment for harmonics 2 3 Slider 4 Corresponding noise adjustment for harmonics 4 5 Slider 5 Corresponding noise adjustment for all the remaining harmonics Slider 6 Noise gate clips the bottom of the analyzed speech spectrum which typically is noisy increased clipping also removes lower spectr...

Страница 26: ...n has the specialty that the synthesis is not made using another filter bank but instead using the harmonic generator where each harmonic amplitude is weighted by the analysis filter bank output that is closest to the frequency of the harmonic This is quite an economic method therefore in the two channel version the synthesis part could be made with two separate outputs whose characteristics can b...

Страница 27: ...ltage changes slowly When Slider 11 is on the spectrum follows the original one a little better but because the analysis filterbank has good resolution the fidelity is quite good also when all sliders 9 11 are off Smoother spectral interpolation helps to attenuate any possible clicks when the pitch changes rapidly this is because there is no synthesis filterbank that would smooth the time response...

Страница 28: ... simultaneously switching the mode selector from 6 or 8 to 7 Now the spectrum at the switching moment will be frozen and you can continue playing in the same way as in Mode 6 except that no microphone is needed any more Leave envelope input 8 open or grounded 2 Transient capture Keep the three position toggle switch in the middle position gate off and leave envelope input 8 open or grounded Then m...

Страница 29: ...oder works best with human voices but still some instruments also come pretty realistic thanks to the large number of analysis filters and their good time domain performance The obvious limitations in instrument replay are due to the fact that non harmonic nature of the signal is not retained which means that most percussion instruments are not reproduced well Also the overall spectrum envelope ma...

Страница 30: ...velope 7 optional CV note input if the PCB switch is closed envelopes 6 and 8 N C Notes Vocoder is typically used without external envelope modulation in that case connect all the envelope inputs 1 5 to the D C out output for enabling the corresponding functions Outputs Output is normally from the out TRS jack Adjustments adjust 1 spectral shift for base note big speaker small speaker adjust 2 spe...

Страница 31: ...l the relative amplitude difference between the two voices Sliders 23 26 determine the key followed by the interval sliders 17 22 These have on off function now used as binary coders with 23 as the least significant and 26 most significant bit When all are off the key is C major A minor when only 23 is raised the key is B major Gsharp minor when only 24 raised B flat major G minor etc See the Tabl...

Страница 32: ...ure 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 32 ...

Страница 33: ...le outputs Noise modulation strength using adjust 1 Phase modulation strength using adjust 2 Mode 1 15 harmonics individual modulation control 1 Connect envelope generator outputs to all those of the envelope inputs that you have activated for the desired harmonic sliders Only 15 harmonic sliders used in this mode 2 If you want to use the noise and or PM modulation features connect also envelope g...

Страница 34: ... 1 15 to set the harmonic spectra Use Sliders 16 27 to set the pseudofilter spectral response Use Sliders 28 29 and 30 to select the noise or PM modulation strength selectively to three harmonic ranges 1 2 3 5 and 6 15 correspondingly Mode 5 True chorus with 10 chorus members each having maximum of 19 harmonics Also possibility to generate non harmonic overtones 1 Connect envelope generator output...

Страница 35: ...MIDI input module outputs use adjust 1 to control the envelope shape see Figure 4 use adjust 2 to control the envelope duration and relative delays between the 8 possible trigger events Mode 14 Frequency modulated harmonic generator 1 Connect envelope generator outputs to all those of the envelope inputs that you have activated for the desired base note harmonic sliders Only 10 harmonics are used ...

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