Inovonics David IV Installation & User Manual Download Page 35

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The user must thus exercise conservative judgment and avoid

overuse of Multipressor and other ‘sound-enhancement’ fea-

tures to meet both the letter and the intent of the

Recommen-

dation

ADAPTIVE PRE-EMPHASIS

FM broadcasting makes use of audio pre-emphasis in transmis-

sion and complementary de-emphasis in the receiver. This

practice requires special consideration with respect to program

peak control.
FM pre- and de-emphasis characteristics (curves) were estab-

lished in the 1940s. These were far simpler times in radio pro-

gramming, long before the term ‘competitive loudness’ was on

the lips of Program Directors. Broadcast practices and record-

ing techniques from that era did not anticipate today’s sizzling,

high-energy, closely-mic’d and heavily-EQ’d music trends.
Today’s program material severely taxes the ability of the FM

transmission channel to pass content transparently. High fre-

quency energy must be controlled independently of the broad-

band levels, a necessity that can make music sound as ‘dull’ by

today’s standards as, in fact, any recorded music might have

sounded to many of us if transported back to those earlier

times.
The DAVID IV utilizes ‘adaptive pre-emphasis,’ a term we

coined to describe an independent high-frequency limiter that

follows the broadband peak controller. Because this HF limit-

ing is performed only in the pre-emphasized domain, a judi-

cious amount of HF clipping is also employed. The clipper al-

gorithm includes proprietary distortion-cancellation techniques

that significantly reduce audible artifacts, particularly those as-

sociated with vocal sibilants.
As seen on the Block Diagram (Page 9), adaptive pre-emphasis

is used only for FM broadcasting. It is a fulltime function for

the composite/MPX outputs, but is applied to the analog and

digital line outputs only in the FM modes, when these outputs

are configured to feed an FM exciter with a built-in stereocoder.
The characteristics of adaptive pre-emphasis are set when the

pre-emphasis selection is made: 75 microseconds for the West-

ern Hemisphere, 50 microseconds for Europe and most other

export areas. Pre-emphasis verification is covered on Page 36.

Summary of Contents for David IV

Page 1: ...DAVID IV FM Audio Broadcast Processor Installation User Guide www inovonicsbroadcast com ...

Page 2: ......

Page 3: ... 2 Software Rev 2 Inovonics Inc 5805 Highway 9 Felton CA 95018 Tel 831 458 0552 Fax 831 458 0554 Register online at www inovonicsbroadcast com PRODUCT REGISTRATION RECORD Model 719 Serial No _______________ Purchase Date _____________________ Warranty Registered Mail Web Reg Date __________ By ____________ ...

Page 4: ......

Page 5: ...n Setup Using the Software UNPACKING AND INSPECTION 10 MOUNTING 11 Rack Requirement Heat Dissipation AC MAINS POWER 11 Mains Voltage Selector Mains Fuse Power Cord RADIO FREQUENCY INTERFERENCE RFI 11 Location Ground Loops PROGRAM LINE INPUTS 12 AES Digital Input Analog Line Inputs Unbalanced Operation PROGRAM LINE OUTPUTS 13 AES Digital Line Output Analog Line Outputs Unbalanced Operation COMPOSIT...

Page 6: ...ce of AGC Action Using Test Tones Adjusting Input Gain THE HIGH PASS FILTER 20 OPTIMIZING AGC ACTION 20 Defeating the AGC AGC Correction Rate AGC Maximum Gain STEREO ENHANCEMENT 22 Stereo Width Solo Width L R Energy and Watchdog Limiter THE FIVE BAND MULTIPRESSOR 23 Compressor Drive Spectral Loading Band Coupling PROGRAM EQUALIZATION 25 The 5 Bands Defined BASS CHARACTER ENHANCEMENT 26 Punch and R...

Page 7: ...LEX OUTPUT 36 Confirming Pre Emphasis Mono Mode and Pilot Injection Adjusting the Multiplex Outputs Multiplex Output Servo RDS SETUP 38 PROCESSING PRESETS 39 Factory Presets Creating Custom Presets What am I listening to Deleting Presets Exporting and Importing Presets PROOF MODE 41 ADMINISTRATIVE SETTINGS 41 Passwords Lost Password Hard Reset Display Brightness Section IV NETWORKING THE DAVID IV ...

Page 8: ...rk Connection Running the Software REMOTE CONTROL OF THE DAVID IV 53 Presets Processing Setup Admin Software Sliders PROFILE AND PRESET FILE MANAGEMENT 55 Saving a Profile Saving a Preset Section VI UPDATING DAVID IV FIRMWARE THE FIRMWARE UPDATER 59 Warning Firmware Update Files Running the Firmware Updater Aborting a Firmware Update ERRATA NOTES AND DOODLES 62 INOVONICS WARRANTY INSIDE BACK COVER...

Page 9: ...ures Leading features of the Inovonics DAVID IV include Intelligent gain riding AGC to correct wandering levels from the console or playout system and to maintain long term consistency between diverse program sources without upsetting the tonal balance 5 bands of dynamic range compression and equalization to help create a sonic signature tailored to the station s personality The DAVID IV s low bas...

Page 10: ...ures disabled or by passed Unless otherwise expressed or implied herein this is the case with figures shown here as indeed seems also the practice of our worthy competitors Frequency Response Composite MPX Output 0 25dB 20Hz 15kHz assuming the use of a lab quality FM multiplex de coder with the appropriate de emphasis characteristic L R Analog Line Outputs 0 25dB 20Hz 15kHz through an ap propriate...

Page 11: ...outputs are in dependently adjustable between 0 8V p p and 8V p p 11dBu correspond ing to 100 carrier modulation source impedance is 75 ohms Pre emphasis may be set to 75µs 50µs or OFF Pag es 13 36 RDS Input Unbalanced bridging BNC input ac cepts a 57kHz RDS subcarrier at any level between 0 5V p p and 5 0V p p for a typical injection level of 5 of total carrier modulation Pages 14 38 19kHz RDS Sy...

Page 12: ...When set to the FM mode s the line outputs are subjected to the programmed delay as well Page 32 THE USER INTERFACE Front Panel A front panel graphic display and jog wheel allow easy menu guided in situ setup and operation of the DAVID IV LED bar displays indicate in out levels and audio processing ac tion Page 16 Software Control The IP network port and supplied soft ware allow remote setup and o...

Page 13: ...PRESSORS BASS CHARACTER AUGMENTATION BASS EFFECTS FILTER BAND RECOMBINING BROADBAND LIMITER STEREO GENERATOR DE EMPH COMPOSITE CLIPPER COMPOSITE COMBINER AUTO SERVO PILOT BYPASS SWITCHING AND LEVEL RDS INPUT RDS SYNC MPX OUT 1 MPX OUT 2 DIGITAL LINE OUT ANALOG LINE OUT ADAPTIVE PRE EMPHASIS OPTIONAL DIVERSITY DELAY PHONES MONITOR MPX POWER CONTROL SWITCHING AND LEVEL ...

Page 14: ...uctions on networking the DAVID IV UNPACKING AND INSPECTION As soon as the equipment is received inspect carefully for any shipping damage If damage is found or suspected notify the carrier at once and then contact Inovonics We recommend retaining the original shipping carton and pack ing materials for return or transshipment If returned for War ranty repair shipping damage sustained as a result o...

Page 15: ...nnect the mains cord and then remove the top cover of the unit A clearly marked slide switch is directly behind the AC mains connector on the circuit board Use a small screwdriver to set the switch for 115V or 230V operation Mains Fuse It is important to install the appropriate fuse as noted on the rear panel next to the fuseholder A for 115V mains A for 230V operation Fuses are the GMA S500 type ...

Page 16: ...nalog Line Inputs The DAVID IV has electronically balanced transformerless left and right channel ANALOG INPUTS with female XLR connectors These are bridging high impedance inputs They do not pro vide termination for the console or other equipment that feeds the DAVID IV Here s why With few exceptions audio line impedance matching is ridi culed by today s hip broadcasters you and erudite equipment...

Page 17: ...tal output level shown below the slider control corre sponds to program peaks limited to 100 modulation and may be adjusted between 0dBFS digital full scale and 20dBFS Analog Line Outputs Male XLR left and right channel ANALOG OUTPUTS on the rear panel are electronically balanced This means that they are ground referenced and are not transformer coupled Analog line outputs may be adjusted to any l...

Page 18: ...ilot component of the FM multiplex signal This waveform may be used to synchronize an RDS Radio Data System encoder with the stereo pilot RDS Input The RDS INPUT BNC connector accepts the 57kHz RDS subcar rier for combining with the FM multiplex program signal The p p level of the subcarrier can range from 0 5V to 5V corre sponding to a typical injection level that s approximately 5 of total carri...

Page 19: ... and readouts Networking the DAVID IV is covered in Section IV Page 43 and software operation in Sec tion V Page 50 We recommend starting with front panel set up however as this method not only gives the immediate grati fication of a hands on experience but is necessary in any event for initiating network connectivity USER ADJUSTMENT GROUPINGS User adjustments for DAVID IV operation are divided in...

Page 20: ...ll operation almost immediately Setup and processing parameters in use previous to the power interruption are reloaded instantly from non volatile memory to the processing core Brownout Detection Although the DAVID IV power supply and digital logic circuits are capable of operation at AC mains voltages down to about one half of nominal the graphic display and LED readouts may fail to give consiste...

Page 21: ...al in the desired injection If you make a mistake for example you might push the jog wheel off center which could rotate it also and bring up the wrong menu simply push the Back button to return to the pre vious menu and try again Menu Timeout and Screensaver Once an adjustment is made you may press the Back button to eventually return to the Main Screen or simply leave any cur rent screen showing...

Page 22: ... to the station s signature sound The sole purpose of the AGC is to normalize levels ahead of the other processing stages with out adding coloration This is possible only with a wideband AGC which should always be the first stage in any comprehen sive audio processing system Multiband AGC is a misnomer Long term leveling in individual frequency ranges may have utility in some instances but using t...

Page 23: ...wheel to dial in the re quired gain With program material playing adjust Digital Gain or Analog Gain so that the front panel AGC gain indicator the AGC GATE LED bargraph hovers around 0dB most of the time This will show that AGC action is more or less centered and working in its sweet spot AGC is a slow long term gain riding function You cannot rush this step as there will be a delay of many secon...

Page 24: ...turntable rumble say what noisy studio air conditioning or do a lot of outdoor sports remotes in windy stadiums This high pass function has been included in the DAVID IV de sign to define a low frequency limit to the station airchain But the use of this high pass filter should generally be considered a Band Aid fix for problems that are best addressed at their source OPTIMIZING AGC ACTION Access t...

Page 25: ...ections on the fly watching the meters with nary a blink Really fast AGC might be justified in an aggressive pop music format Even at its fastest AGC in the DAVID IV shouldn t alter the perceived dynamics of the program although it will defi nitely erase level variations in a hurry The faster settings might cause AGC action to be audible in speech a talk show for instance but probably not in a hig...

Page 26: ...g only to illustrate what s intended and to give a number for set up reference Stereo Width is active only on stereophonic program material it does not imply any sort of stereo synthesis from a monaural source Solo Width The Solo Width slider on the other hand acts only on center channel monaural material Nearly all contemporary music is recorded in very sterile multitrack sessions Generally each ...

Page 27: ...vides the program audio into five discrete frequency bands with crossover points and filter slopes optimized for each range of frequencies Each band undergoes dynamic range compression with the threshold waveform response transfer function and attack release timing engineered for the most ef fective action within each band Multipressor parameters have been derived from exhaustive tests by a core o...

Page 28: ...s at their fundamental frequencies whereas a band or orchestra will have a broader spectral profile with energy spread over a wide range of frequencies Spectral Loading brings down the energy where it is the highest and brings up the low levels at other frequencies As displayed on the RTA the shape of the audio spectrum will be flatter and the sound of the program will appear busier Spectral Loadi...

Page 29: ...ith puny speakers It covers a range that includes male voices Excessive energy in this band tends to make the program sound tubby or muddy Mid This is the articulation region pretty much smack dab in the center of the audible range Female vo cals and the melody in music reside here Pres Presence frequencies are responsible for bright ness aliveness immediacy and closeness the ef fect that the prog...

Page 30: ...cience be your guide Despite the desire for that solid and pervasive bottom end resist the temptation to run both these controls to the max And when setting them make sure you are listening over a system that can reproduce the ef fects you are dialing in There is one caveat with respect to the bass enhancement sec tion one that is hinted on the Block Diagram Page 9 Bass ef fects are added back int...

Page 31: ...ree of distortion would deliberately be introduced much less tolerated Please allow us to debunk this knee jerk reaction The only truly undistorted waveform is a pure tone a sine wave It is a symmetrical waveform and the positive and nega tive halves are mirror images of one another The PIPP limiter would divide limit and recombine these halves to create a spit ting image of the original an amplit...

Page 32: ... does not include waveshape symmetry management The third choice ITU is a special purpose limiting mode that en sures compliance with an international broadcasting standard practiced in certain European countries This is discussed in detail under the next subheading Action of the PIPP limiter was described earlier and use of this function will be predicated on how particular program material sound...

Page 33: ...ng of the Limiter Density control is determined en tirely by subjective evaluation of the on air sound Density is one very important quality of the station s signature sound and no other control has a greater effect over perceived loudness The factory default value is a setting of 5 0 the center of the control range No setting is considered a wrong one but the range extremes will probably be releg...

Page 34: ...U option is selected First the PIPP limiter is defeated in favor of more conservative symmetrical peak control Secondly the Limiter Drive and Limiter Density sliders are re scaled for less aggressive overall pro cessing The Limiter Density slider is in fact renamed in the ITU mode becoming the dBr BS 412 9 slider shown above This slider calibrated to the multiplex r m s 0dBr value cited in the ITU...

Page 35: ...sity that can make music sound as dull by today s standards as in fact any recorded music might have sounded to many of us if transported back to those earlier times The DAVID IV utilizes adaptive pre emphasis a term we coined to describe an independent high frequency limiter that follows the broadband peak controller Because this HF limit ing is performed only in the pre emphasized domain a judi ...

Page 36: ...eive the program in the usual manner and new HD Radio receivers can recover both the ana log and the digital versions of the program Because there is an obligatory delay of some 8 seconds in the digital program encoding and decoding process the analog sig nal must be delayed by this same amount to arrive in sync with the digital signal The HD Radio receiver first tunes and plays analog audio to th...

Page 37: ...ut anticipates welcome improvements in the encod ing decoding process of the HD Radio system To enable the delay highlight and select Enable Next High light the Delay slider and then push the knob Now turn the knob to set the time to 8 seconds and push it to activate the setting NOTE To obviate frustration and blisters the DAVID IV will race through the 1ms increments at an accelerated rate when t...

Page 38: ...Output Characteristic The checkboxes on the left select the characteristic of the pro gram line outputs These are the choices 20kHz Flat 20k Flat is a full range 20kHz output that comes directly from the output of the broadband peak processor This output is suitable for any form of full power bandwidth digital radio broadcasting for audio production and recording or for high quality streaming The ...

Page 39: ...ffset is historically on the order of 20dB for raw unpro cessed audio but since the output of the DAVID IV is tightly peak limited there is no headroom issue even when this is set wide open at 0dB Nevertheless running program peaks to 0dBFS is not a good idea because of what s called zero dBFS plus a phenomenon leading to overshoots clipping and dis tortion in the eventual D to A converter somewhe...

Page 40: ...ilter and adaptive pre emphasis for FM transmission The volume control next to the jack adjusts only the headphone volume COMPOSITE MULTIPLEX OUTPUT The DAVID IV has two independent outputs for the compo site MPX multiplex signal These outputs include the S L R S L R 19kHz Stereo Pilot and optional RDS subcarrier com ponents that comprise the FM baseband signal Navigate to Setup Stereo Generator C...

Page 41: ...ng remains an available option in mono The factory default setting of 9 0 stereo pilot injection is normal for all FM transmissions although the value may be set anywhere between 6 and 12 To reset the level to a non standard figure turn the jog wheel to place the brackets around the Pilot Level slider push the knob and then turn it to adjust the injection level Adjusting the Multiplex Outputs Pres...

Page 42: ...display adver tising or music artist and title info on the faceplate of RDS ra dios An external encoder is required to generate the RDS subcarrier When RDS is enabled the DAVID IV supplies a synchronizing signal to lock the encoder to the stereo pilot and a self metering combining network to add the RDS subcarrier to the composite MPX output signal Additional details may be found in Section II Pag...

Page 43: ...te to Presets Turn the knob to scroll through a list of 25 factory F presets and 20 more shown as Empty Factory Presets The 25 factory F presets are named for genres of music or other programming formats that are common in today s con temporary radio broadcasting The processing presets were painstakingly crafted by our team of qualified consultants ranging from classically trained musicians to tee...

Page 44: ...nd scroll to the bottom of the list Highlight Delete and push the knob X Delete will begin flashing Turn the jog wheel to highlight any user preset the list will not even show the factory F presets Your selected preset will flash and when you push the knob it will be deleted If you happen to delete a user preset that is currently on air the name on the list will revert to Empty but the processing ...

Page 45: ...how audible these artifacts are to listeners ADMINISTRATIVE SETTINGS From the main menu navigate to Administrative Passwords DAVID IV settings may be protected by a password which must then be entered before any subsequent changes can be made The password will apply both to changes made from the front panel with the jog wheel and to changes made via software control of the DAVID IV Highlight Secur...

Page 46: ...er to Enable the password when finished Lost Password Hard Reset To recover control of the DAVID IV if the password is lost you must do a hard reset of the unit This is accomplished by holding down the Back button as AC mains power is removed and then reapplied WARNING A hard reset not only deletes the password but will also return the DAVID IV to all factory default values Custom presets the curr...

Page 47: ...o a router server port on your network all settings on the IP Settings screen should populate at once as they did in the image above Dynamic IP addressing is common with DHCP mode routers and servers allowing multiple networked devices to share a limited range of IP addresses When one device disconnects from the network its address may be reassigned to another de vice as needed Whether connecting ...

Page 48: ...al data entry process must be repeated for these IP Settings fields Gateway Subnet and DNS Entries in these fields will be dictated by existing network protocols depending on how the server or router is configured Your Network Adminis trator should know all about this it is not within the scope of this manual to provide a tutorial on network setup Sufficient to say that DHCP operation is the prefe...

Page 49: ...orwarding service may be free of charge but advanced features can command a nominal annual fee These services require registration on the appropriate Website Navigate to Setup Network Dynamic DNS Bracket the Mode field and push the knob Next turn the knob to reveal the three Dynamic DNS forwarding services These are dyndns org no ip com and dnsomatic com Put the traditional www ahead of these link...

Page 50: ...ly when the IP address changes but it also must check in fol lowing a power interruption and whenever the Dynamic DNS mode is changed in any way Some small part of the forwarding provider s processing re sources is used each time an IP address is renewed These pro viders especially the for free ones don t appreciate repeated and unnecessary IP address renewals If a particular account makes a nuisa...

Page 51: ... the IP address of any computer that is currently communicating with the DAVID IV over a network connection DIRECT COMPUTER CONNECTION TO THE DAVID IV If your station does not have a local network you may still use the rear panel NETWORK PORT connector to connect your DAVID IV directly to a PC both for using the supplied setup and operating software to control the DAVID IV and for per forming firm...

Page 52: ... pane shown below on the left Scroll down the list of items and highlight In ternet Protocol TCP IP Then click Properties just under the list to bring up the Internet Protocol TCP IP Properties pane shown below on the right Chances are that if your computer is used mainly for Internet activity on a LAN or wireless network it may well have a button set to Obtain an IP address automatically like our...

Page 53: ...put the DAVID IV on this same imaginary network Using the jog wheel in the manner described under Manual IP Setup Page 43 enter IP settings for the DAVID IV as follows Static IP IP 192 168 5 2 Gateway 192 168 5 1 Subnet 255 255 255 0 DNS 192 168 5 1 This sets up the DAVID IV to communicate with your PC Cable them together with a short CAT5 straight through Ethernet cable Now you may start configur...

Page 54: ...via software are immediately sent to the unit s firmware This is then echoed back to the software for display on the computer screen If communication is lost the DAVID IV continues working indefinitely with the parameters set at the time the link was broken even through local power interrup tions These settings will again be reflected on the computer screen immediately upon reconnection INSTALLING...

Page 55: ...g a Network Connection Before starting the software utility check to see that your com puter and the DAVID IV are both connected to your local net work Using the front panel jog wheel navigate to Setup Network Status If the DAVID IV has a network connection the menu screen should look something like this The screen tells us that the unit does indeed have a local net work LAN connection but no Inte...

Page 56: ...rotected the DAVID IV with a password Page 41 then you must type that into the En ter Password box on the right Now click the Connect button to invite the software to com municate with the DAVID IV Interactivity will be indicated by appearance of the bargraph readouts at the top of the screen Any connection problems will display a comment below READY TO CONNECT as shown in the next screenshot The ...

Page 57: ...tatus on the DAVID IV you will see your computer connected as shown here REMOTE CONTROL OF THE DAVID IV Once connected any operation that can be performed with the menu guided front panel jog wheel can be duplicated at a re mote location using the DAVID IV software routine This in cludes setting all input and output levels adjusting all pro cessing parameters and using and saving processing preset...

Page 58: ...ou select any preset from the list by double clicking it As you change or fine tweak any processing parameter the NOW PLAYING PRESET name will change immediately to None In other words the preset that was on air has been modified and needs to be saved with a new name Click Save New Preset and a pop up box will appear Name your new preset and click OK Your preset will become resident in DAVID IV fi...

Page 59: ...if the optional delay board has been installed Page 32 All sliders and radio buttons on these tabs reflect the DAVID IV menu driven jog wheel adjustments which have been explained in Section III Admin This tab gives access to the Administrative settings the securi ty password utility a place to enter the IP address of the DAVID IV to enable communications and selection of the Proof mode Adjusting ...

Page 60: ... want to sound the same Saving a Profile Click File at the top of the software screen The first two options Save Pro file to File and Load Profile from File refer to all settings and custom presets cur rently resident in the DAVID IV firm ware This includes processing prefer ences input and output level settings RDS injection in short everything that has been adjusted either by the front panel jog...

Page 61: ... IV User presets are saved individually as single files A preset file will not include setup parameters levels RDS in jection etc but only the processing adjustments for that par ticular single preset This means that a preset file can be used among multiple installations that all want to sound the same but the imported preset will leave in out levels and other setup parameters properly adjusted fo...

Page 62: ...older created the same fashion as described under the Saving a Profile heading Page 56 The file with that preset will be saved with its listed name and a D4p extension Importing a preset is just the reverse process Click Import a Preset navigate to the folder on the computer where presets are held Highlight the preset and click Open The saved pre set will be added to the list both on the software ...

Page 63: ...e your level and other setup parameters plus factory and user processing presets Firmware updates are bootloaded into the DAVID IV A bootloader is a simple software routine that runs on a PC con nected to the DAVID IV Refer to Section IV for specifics on in terconnecting the DAVID IV to your computer either over a LAN network connection Page 43 or directly with a CAT5 ca ble Page 47 Firmware Updat...

Page 64: ...et of files looks like the one below Running the Firmware Updater Navigate to you temporary Desk top folder and double click the exe file arrow above That will bring up this Information message advising that the Firm ware Updater does not yet find the DAVID IV Click OK This will start the Firmware Updater and display the main screen This screen outlines the firmware update process in three easy st...

Page 65: ...ick OK as directed at the end of the upload The DAVID IV will revert to the main menu where you can confirm the version number of the uploaded firmware Aborting a Firmware Update Before you have committed to a firmware update pushing the Back button will return you to previous screens effectively aborting the update process But once you see this message on your DAVID IV it is almost too late to tu...

Page 66: ... 62 NOTES AND DOODLES ...

Page 67: ...modification or if the serial identifi cation label has been removed or altered III TERMS OF WARRANTY Inovonics Inc products are warranted to be free from defects in materials and workmanship A Any discrepancies noted within THREE YEARS of the date of delivery will be repaired free of charge or will be replaced with a new or remanufactured product at Inovonics option B Parts and labor for factory ...

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