LecNet2 - Sound System Design Guide
Contents
1. 4 2 Remote Control m X X 4 AUTOMATIC Microphone MEDIAS e a iaa 5 Loudspeaker ZONA a ia 6 Digital Matri and BUS t o E 7 Teleconferencing with DM Series aaa a a aaia aaa Aaa a aiaia 8 zi TA 8 slc T Q 8 BE A nnhleduzipfetc 8 Vid o Follow Audio A duciei idgdlde c M 10 DSP Features ana UI c 11 LecNet2 Audio COMPONENTES e 12 A Au 12 12 Big prc saeco seauas 12 DNIO O2. 22 The PAG NAG Computer Progra t Eo Loo rm 22 22 NA 22 What About Loudspeaker Power emision ii iii inicia 23 PAG NAG Software GUI m 24 Introduction to Writing Macros Lec NeT ceci 24 ERE aE e EE EA E E EN T IE E TA E E EEN EREE E NN AA A AE E E 24 B A A 24 A A 24 o SAA 24 Fern ic E 24 Creating Macros o PP EAEAN EErEE 25 Assigning Macros to i i ist TC 25 mos MT E A 25 Brief History of Product Development ae 26 www lectrosonics com 3 LecNet2e LecNet2 Overview The LecNet2 product group introduces a powerful series of audio components and unique solutions for the design and installation of audio systems This Design Guide provides basic information on LecNet2 components automatic mixing the mix minus approach to loudspeaker zoning and specific information on audio teleconferencing A variety of sound system block diagrams are included as examples of different applica tions for LecNet2 components Applications for LecNet2 products include worship centers courtrooms paging systems training and conference centers council chambers and hotels A single LecNet2 sound
3. Needed Acoustic Gain NAG is a measure of how much reinforcement a sound system must provide so that distant listener can hear a talker at a sound level comparable to when the listener is near the talker As an illustration assume that a listener near the talker experiences an average sound pressure level SPL of 75dB in normal conversation without sound reinforce ment Next assume that a more distant listener hears the same conversation at an average level of 62dB This level would be low enough that intelligibility could be a problem particularly in the presence of sound back ground noise For the distant listener to hear normal conversation at the same average level as the nearby listener i e 75dB SPL an extra 13dB is needed at the distant listener s position This is the Needed Acoustic Gain NAG for this example In order to make a NAG calculation using GAINCALC the boxes labeled Dm DO Ld and Lr must be filled in The formula for calculating NAG is NAG Lr Ld 20Log10 Dm DO As should be clear NAG is a function of the physical distances between talkers and listeners As yet nothing has been said about a sound system If the NAG value is positive which it generally is a sound system will be needed to provide acoustic gain at least equal to the NAG for the distant listener in order that they hear the same SPL as the nearby listener This leads to the PAG calculation Download the program FREE from the web
4. CD Player R CD Player Satelite R SaroliteL VCR Audio R VCR Audio L DVD Audio R DVD Audio L Table Mic 4 Audience Zone 4 Audience Zone 3 1 Audience HARD DISK RECORDER Zone 2 JUDGE 7 1 Council Mie 5 Council Mic Council Mie 7 Council Mic 8 aie K PA Zone 4 DEFENSE K PA Zone 3 PA Zone 2 Audience aes eS A DM1624 PROSECUTION PA Zone 1 WITNESS JURY DM1612 in Multi Room Collegiate Distance Learning ombining Multi Purpose Hall LECNET2 85 232 TRS V jose ee onma sus ne raes tron AMX CONN ousus eva omnis neas E Four Serial Ports Out LECNET usn mau oes me nues rw sous nce conec iv morne LEVEL Video Codec B auxin LeveL B OUT ue Leve aux our uve LeveL E reco une revo ronr conec Telephone 1 1 1 1 1 1 1 l 1 2 Wire POTS Line 1 l 1 1 PPPPPPPPPPPPPPPP Tm DMTH4 32 Analog Cont on 25 pin du ETS Ls Beck E i Assistive Listening Feed Satellite L Satellite R VCR Audio R VCR Audio L Video Tape Feed DVD Audio R DVD Audio L PPPPPPPP ix 5 6 Analog Remote Control Panel www lectrosonics com 15 LecNet2
5. The Mix Minus approach to loudspeaker zoning elimi nates both of the problems mentioned above Individual outputs from each microphone channel are delivered only to loudspeakers located far enough away from the microphone to eliminate feedback In essence the microphones and loudspeakers are physically decoupled Mix Minus systems using automatic mixers are even more stable against feedback since the automatic NOM attenuation in the mixer reduces the gain on unused microphones Mix Minus routing does not change the way an automatic mixer operates and in combined units such as the DM Series matrix mixers all of these functions are seamlessly integrated MIX WITH MICS 3 4 5 6 MINUS MICS 1 AND 2 DM812 DIGITAL AUTOMATIC MATRIX MIXER DSP WEN oo E POWER AMPLIFIER POWER MIX WITH MICS 1 2 5 6 MICS 3 AND 4 As an example consider a conference room with multiple microphones and ceiling speakers Assume the average distance from a microphone to its closest loudspeaker is 6 feet Using a DM matrix mixer a Mix Minus feed can be generated for each loudspeaker that does not include the microphones close to each specific loudspeaker If for example the next closest micro phone to a loudspeaker is on the order of 12 feet away the sound system will have picked up 6dB more gain before feedback In difficult acoustic circumstances 6dB may be the difference between a functioning sound reinforcement system
6. 12 2 Mix Mix Control Quad RJ 45 Conn G 24 2 Submix Mix Control 2 2 DM Series Slave Processor Quad RJ 45 Conn Lx U S Patent Number 5 414 776 PROGRAMMABLE INPUTS OUTPUTS EXPANSION IN 11 OUT5 16 IN4 21 OUT2 E Ju E e 20 21 do E de E M D A B LecNet um DSP LECTROSONICS wy 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 1 lo de MADE IN U S A Audio Submix and Data Forward Propagation MASTER I MIC LINE OUT 4 1 2 3 Sikis Se Audio Final Mix and Data Back ea CODEC RC TEL RC Submix and Data Forward Propagation SLAVE This device complies with les o the 14 ns 1 ndesired operation s POWER i 902 z 15W PROGRAMMABLE INPUTS OUTPUTS EXPANSION Audio Final Mix and Data Back Propagation U S Patent Number 5 414 776 LECTROSONICS INC CCOO AA IN U S A U S Patent Number 5 414 776 TELEPHONE HYBRID LECTROSONICS INC SET LINE Miniatur oe or Re MADE IN U S A 2 SLAVE www lectrosonics com LecNet2e Teleconferencing with DM Series Processors The fundamental problem in teleconferencing with a ERL sound system is microphone speaker acoustical coupling as is illustrated below Far end audio is delivered by the loudspeakers in t
7. OUT 17 OUT 18 OUT 19 OUT 20 OUT 21 OUT 22 OUT 23 OUT 24 Assistive Listening Feed Video Tape Feed the speakers near the freshmen seats in the back of the room to the front program speakers All of this is possible with just three DM1624 mixers power amplifiers and speakers No additional signal processing devices are required The touch screen control system can be easily pro grammed using simplified serial command strings and up to 128 resident macros Up to 24 presets allow global recall of settings for alternate setups E LecNetge M Calculating PAG NAG and POWER The PAG NAG Computer Program What is PAG The GAINCALC software is a proprietary program offered by Lectrosonics on our CD ROM and by down load from the web site as a part of the LecNet2 sound system Designer s Kit The supplied software includes EPS graphic files of LecNet2 M component control panels block diagrams in DXF format of the sound system examples illustrated in this guide and engineer s and architect s specifications in TXT format for all LecNet2 components The GAINCALC program which runs under Windows 98 NT XP is designed to automate calculations of PAG NAG and loudspeaker electrical power requirements for any type of indoor sound system The following are descriptions of each of the three parameters calculated by the program and some information about how those calculations are made What is NAG
8. 12 BlIHLo n 13 ft T E 13 PNPA T T PP M HH PR 13 NY TMU ARO COIN Me 13 Wied Remol CONTOS 14 nn PP 14 o 14 alg 14 o I PH 14 Example Sound System Designms aaa 15 Boardrooms Traning and Conference E RH PENNE 15 Contacta 15 2 i0 OO OWING se sorte singe sentence cides Eos 15 Worship Center Automated Sound Systems pp 15 15 Collegiate Distance Learning Multi Purpose Hall e eeeiiiiiiiiieeeeeeeeeeeeeee enne nennen nennen nennen nnne 15 Boardrooms Traning and Conference Centers pp 16 Worship Center Automated Sound Systems pp 17 Gou rnroom cound bol SS s TT MN RN RET 18 AAA T T 19 o A 20 Collegiate Distance Learning Multi Purpose Hall pp 21 cal maung FAG NA POWER m
9. Control Panel Larger systems can be configured with additional DM units connected via the expansion ports For example two DM84 mixers can provide 16 inputs with eight outputs An alternative would be to choose a larger DM matrix mixer such as a DM1612 or DM1624 companion disk for macro examples LECTROSONICS INC Collegiate Distance Learning Multi Purpose Hall Crestron AMX Four Serial Ports Out Video Codec Telephone 2 Wire POTS Line Tape Deck R Tape Deck L Satellite Satellite R VCR Audio R VCR Audio L DVD Audio R DVD Audio L TY Y TTT LECNET2 RS 232 TRS 1 8 LECNET2 USB DANI BUS TX RJ45 DANI BUS RX RJ45 CODEC IN MIC LINE LEVEL AUX IN MIC LINE LEVEL A CODEC OUT LINE LEVEL AUX OUT LINE LEVEL HANDSET LINE TELCO LINE REMOTE PORT CODEC h REMOTE PORT POTS ph DMTH4 Analog Control Port 25 pin d sub LECNET2 RS 232 TRS 1 8 LECNET2 USB OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 OUT 6 OUT 7 OUT 8 OUT 9 OUT 10 OUT 11 OUT 12 OUT 13 OUT 14 OUT 15 OUT 16 OUT 17 OUT 18 OUT 19 OUT 20 OUT 21 OUT 22 OUT 23 DM1624 0000000000000 000000000000 0000000000000 000000000000 OUT 24 Analog Control Ports 25 pin d sub DANI BUS RXRJ45 BUS TX RJ45 S DANI BUS RX Ru45 DANI BUS TX RJ4s f DANI BUS RJ45 DANI B
10. Network connections to LecNet2 devices are possible using the PC hosted LecNet2 Net Server program In either case complete control is possible by sending commands using the HTTP protocol with even a humble web HTML page capable of simple functionality LecNet2 is an open system for which controllers are easy to implement It is worth noting that the command terminal program is capable of accessing LecNet2 devices using any of the three connection types mentioned above and may be used as a remote control and configuration tool for all LecNet2 devices We think you will agree LecNet2 offers unprecedented flexibility and convenience for remote control developers and system designers LECTROSONICS INC System Design Guide Automatic Microphone Mixing Algorithm Sound reinforcement systems with multiple micro phones and a distributed loudspeaker system are the rule in conference rooms training rooms and board rooms In many cases the room has a low ceiling which increases the acoustic coupling between loudspeakers and microphones creating a significant challenge to providing adequate gain for sound reinforcement without acoustic feedback In larger rooms with longer reverberation times reinforced sound is re circulated through multiple open microphones which can severely reduce the intelligibility of the overall sound system Automatic microphone mixers are an effective tool to minimize the effects of multiple microphones All
11. UNICHANNEL In keeping with a total portability concept the first self contained speaker amplifier wireless system was developed during the same period The first VHF high band wireless microphone systems were introduced in 1987 taking the proven UNICHANNEL design to a higher frequency band The product line expanded rapidly over the following 5 or 6 years leading to the introduction of UHF wireless systems in 1993 The first frequency adjustable synthesized UHF wireless system began shipments in 1995 followed by a compact version of the receiver and a complement of belt pack plug on and hand held transmitters In March 1998 the first wireless IFB Interruptible FoldBack systems were shipped This was the first UHF system on the market Being a synthesized UHF design with extended operating range and excellent audio performance the IFB Series was an immediate success Advanced DSP based wireless technology was introduced to the market with Digital Hybrid Wireless systems in late 2002 The technology combines 24 bit digital audio with analog RF to eliminate compandor artifacts and preserve the operating range and spectral efficiency of the finest analog wireless systems The DSP also provides compatibility with analog systems from Lectrosonics and other manufacturers A patent application was submitted prior to shipments in 2002 and has been pending through the date of this document Development in wireless microphone sys
12. a The console operator is thus free to concentrate on church system All of the speech microphones are other mixing and adjustment tasks In addition for passed through the DM84 The direct outs from the worship services where no console operator is present DM84 are then input to separate channels of the mixing weddings funerals etc the addition of the DM84 to console Full control over the speech microphones is the console provides fully automatic operation maintained by the console operator but the DM84 www lectrosonics com LecNet2e Courtroom Sound Systems D LECNET RS 232 D EXP IN EXP OUT B OUT 2 EXP IN 2B B LECNET RS 232 BIN 16 BIN 15 BIN 14 BIN 13 3r AX 307 HARD DISK RECORDER 1 XI ak y DEFENSE K K K PROSECUTION A CLERK WITNESS JURY This diagram shows a typical courtroom sound system including microphones for each of the key people an automatic mixing function and a recording system A 70 volt distributed speaker system is fed from a main output on the DM1612 A multi media rack provides input signals from audio and video recordings LECTROSONICS INC City Council Chamber CD Player 1 out 3 Satellite R Satellite L VCR Audio R Satellite dish A Audio In Audio Out Video in Video Out 4 DVD Player 1 out CH 2 out 3 p p LA p p p p A p P p p This is a representatio
13. it is assigned to run a macro Next click the Test button navigate to the Matrix tab and you will see the changes to the matrix due to the contact of a simulated external button Now select the tab for Programmable Input 2 and assign it to run macro 2 in the same way you assigned programmable input 1 Test it and look at the matrix You now have two simulated external buttons that will affect the matrix with the 3 commands that are assigned in the macros Advanced Macros The material in the above section describes how two buttons can be used to toggle multiple crosspoints In the next example we will assume that the client re quires the same functionality but only with a single button To begin we must modify Macros 1 and 2 with one line of code Open the Macro Editor in the Device menu and select Recall from Device Memory Select Macro 1 and click OK to see the code appear in the edit window Click in the Commands to Execute field and type prgindef 1 14 2 CR Next go to the Device menu and select Store to Device Memory Save it to macro 1 thus replacing your old macro with the new modified version This command prgindef 1 allows you to assign any of the 17 available library functions from the drop down item list such as Run Macro on Close Toggle Mute Inputs Momentary Mute Inputs and so on dynami cally In the help file note that 14 is Run Macro on Close thus 14 2 reassigns programmable inpu
14. made to local microphones and loud speakers it is possible in theory to effectively remove return echo but this is not a very realistic situation The theory behind distributed echo cancelling is that once the DSP has converged it can continue to sub tract far end audio even when the local microphone is open and far end audio is present at the same time there are any changes in gain noise or acoustics in the local space and equipment the DSP must re converge which requires another brief moment with little or no local noise or sound and significant far end audio present A gated automatic mixer does not change the gain when the microphone is open it just turns the channel off and on abruptly This helps with distributed echo cancelling since the microphone is completely muted when not in use but it is very choppy sounding in the local sound reinforcement system A gain proportional automatic mixer applies the most gain to the most active microphone with smooth continuous changes This makes it extremely effective for local sound reinforcement but the continuous gain changes make it difficult for the echo canceller to remain converged and effectively reduce the echoes at the far end The DMTH4 in conjuction with a DM Series processor offers a unique approach to the problems with simulta neous teleconferencing and sound reinforcement The patented adaptive gain proportional mixing algorithm works in conjunction with a c
15. panel controls to a table top surface SLECONFERENCE e LED indicators display status and volume adjustment activity e Soft touch switches e Durable laser engraved nomenclature e Machined aluminum housirig The RCW DMTH4 provides the main operating controls for the DMTH4 hybrid in a remote location The circuit board is mounted in an attractive powder coat finished box Soft touch switches and highly visible LEDs provide simple intuitive operation and instant recogni tion of the status of the DMTH4 Two RCW units would be used if the DMTH4 is connected to both an analog line and a codec This allows independent control of both sources during a bridges three way room video audio conference RCW VLS Remote Level Control for QU Lectrosonics auto mixers models AM8 AM8TC AM8 4 AM16 12 DM84 EE DM812 DM1612 and m DM1624 ES e LED indicates active FS status e Screw terminal connec tions for reliability e Fits single gang conduit e Detented rotary action e Selectable by jumper FULL or 15dB attenuation e 3 conductor wiring The RCW VLS is a rotary volume control mounted on a circuit board and a single gang wall plate for use with Lectrosonics automatic mixers and matrix units The rotary action is detented for a smooth accurate feel and repeatable selection The unit can be connected to control individual channels in any combination or to the main output control p
16. proportional gain algorithm allows for greatly increased intelligibility and DM1624 LECTROSONICS bh 4 DIGITAL AUTOMATIC MATRIX MIXER DSP DM1624 The DM1624 is a 16 in 24 out digital matrix mixer allowing every input to be routed to any or all outputs Automatic microphone mixing using a proportional gain algorithm allows for greatly increased intelligibility and 12 gain before feedback Each input can incorporate up to 6 filter stages plus compressor ADFE and delay Each of the 12 outputs provides a digital delay up to 9 filters and a compressor limiter LecNet 2 DSP PUSH FOR MENU SELECT a POWER gain before feedback Each input can incorporate up to 6 filter stages plus compressor ADFE and delay Each of the 12 outputs provides a digital delay up to 9 filters and a compressor limiter LecNet 2 DSP PUSH FOR MENU SELECT E POWER gain before feedback Each input can incorporate up to 6 filter stages plus compressor ADFE and delay Each of the 24 outputs provides a digital delay up to 9 filters and a compressor limiter LECTROSONICS INC LECTROSONICS wy TELEPHONE HYBRID INTERFACE System Design Guide LecNet 2 DSP a DMTH4 The DMTH4 integrates telephone lines video codecs and external audio sources into the digital bus structure of DM Series processors so these sources operate as though they are another microphone or audio input in the sound system Th
17. www lectrosonics com a Potential Acoustic Gain PAG is a measure of how much extra reinforcement acoustic gain the sound system can be expected to provide for a distant listener above the level at which that listener would hear the talker without any sound reinforcement Following through from the NAG calculation above the PAG of a system should be at least equal to the NAG in order to provide sufficient SPL to the distant listener The PAG calculation is based on the assertion that the SPL generated by the sound system at the talker s microphone can cannot exceed the SPL that the talker produces acoustically at the same microphone If the reinforced SPL exceeds the original SPL from the talker the system regenerates producing what is commonly known as FEEDBACK The closer the loudspeaker is to the microphone or the farther away the talker is from the microphone the lower the PAG of the system will be The other factor in the PAG calcula tion is the distance of the distant listener from the nearest loudspeaker The further the listener is from the speaker the lower the system PAG In order to make a PAG calculation using GAINCALC the boxed labeled DO D1 D2 and Ds must be filled in The formula for calculating PAG is PAG 20L0g10 D1D0 D2Ds Note that the PAG calculated from this formula implies a sound system which is right on the verge of feedback In the Options menu of GAINCLAC you can check FSM Feedback S
18. DM1612 i e each has 12 outputs For the DM1624 24 outputs 24 values would be returned Update In order to change the input gain of a particular chan nel an Update would be sent including the channel number and the value For instance to set the output gain of channel 7 to 6dB the instruction would be 24 7 6 CR In the case where it is required to update 14 of the 16 inputs such as for a DM1612 or DM1624 there is no need to re type the Update instruction 14 times In stead simply use this instruction 1259805 510 0 0 0 0 9 0 0 0 0 0 0 0 0 99 99 The asterisk indicates that all input channels will be addressed the 16 values in the brackets represent the 16 gain settings to be sent to the DM mixer The first element is input channel 1 and the last element is input channel 16 Channels 1 through 14 will be set to OdB channels 15 and 16 will be left untouched as indicated by the 99s in positions 15 and 16 99 is the don t care value for the ingn instruction It is often the case that a mass update should leave one or more values un touched so don t care values are specified for many commands See the online help for a particular com mand to learn more Command If a macro or a preset needs to be invoked a Com mand instruction is used Unlike an Update a Com mand will never set a value And unlike a Query a Command will never ask for a value For example to call preset 1 the in
19. De154 Control Panci Lectrooonic fle dk Ere Macros bek Connect Device Setup iib always effect De mae to to make the state hiber asugrenants procedure to identify and eliminate feedback As the gain is gradually turned up a slight oscillation begins to i oT be audible ringing When the ringing begins a very Ae EE 9 e narrow notch filter is automatically deployed to eliminate the oscillation The filter can then be stored in a Preset to make it permanent Windows Tabbed GUI The graphical user inteface supplied with all LecNet2 Back E Cancel Heb The ADFE setup wizard products uses a familiar Windows tabbed structure E LOCI I E 8 i Tabs across the top of the screen open working pages m to set up the parameters for each type of signal pro E cessing Individual channels are selected and ia a ay other detail setup pages opened with a variety of O buttons in the page display EU A The GUI allows values to be entered directly click and mr A drag setup with the mouse and click and hold buttons t to scroll through available values Setup is intuitive and pr c E med visual displays illustrate the setup parameters as the Emm eid data is entered Windows is a registered trademark of Microsoft Corp www lectrosonics com 11 LecNet2e LecNet2 Audio Compo
20. LecNet2 Sound System Design Guide LECTRHOSONICS wy LE OSONICS A CTR hr d PN TI O 7 7 7 7 7 O O O O O O our s our 4 We our ovr s A A s Aour 10 Am ovr PUSH FOR VR MENU SELECT VENUE RECEIVER LEVEL PHONES HOLD FOR OFF DNIPA12 12 CHANNEL POWER AMPLIFIER 0 o D D 0 D P mN mN EmN 7 MODE USB STATUS PAS LECTROSONICS 4 POWER AMPLIFIER OUTPUT LEVEL LECTROSONICS ww A LECTROSONICS 0 D P EmN ww t 7 E LECTROSONICS hd LECTROSONICS Innovative Hardware S OW OW OW OW ON i tiir Sieg Se Sine DMTH4 TELEPHONE HYBRID INTERFACE STATUS DIGITAL AUTOMATIC MATRIX MIXER DSP D o 0 P PF A o 0 D tQ M P 8 MODE USB STATUS Car 1 O ac ang aci Sam PUSH FOR DM812 MENU SELECT DIGITAL AUTOMATIC MATRIX MIXER DSP DM1612 DIGITAL AUTOMATIC MATRIX MIXER DSP PUSH FOR MENU SELECT 1624 DM1624 DIGITAL AUTOMATIC MATRIX MIXER DSP PUSH FOR MENU SELECT ftware for Automatic Soun Digital Hybrid Wireless LecNet 2 psp LecNet 2 psp LecNet P DSP LecNet 2 psp LecNet 2 psp d Systems LECTROSONICS Rio Rancho NM USA www lectrosonics com LecNet2e Ed LECTROSONICS INC System Design Guide Table of Contents As A
21. US RX RJ45 LECNET2 RS 232 TRS 1 8 LECNET2 USB DANI BUS RXRJ45 DANI BUS f 0000000000000 000000000000 0000000000000 000000000000 Analog Control Ports 25 pin d sub LECNET2 RS 232 TRS 1 8 LECNET2 USB 0000000000000 000000000000 0000000000000 000000000000 Analog Control Ports 25 pin d sub This example illustrates a large distance learning room with forty microphones three site conferencing local Video and Telco and several multi media inputs The design provides extensive signal processing including EQ compression delay automatic feedback suppression automatic microphone mixing mix minus speaker zoning and stereo playback over the main Program speakers large gallery audio feed with time delay compensates for the difference in distance from www lectrosonics com DANI BUS RJ45 DANI BUS RX RJ45 DANI BUS RXRJ45 DANI BUS RAS 4 DANI BUS TXRJ45 BUS RX RJ45 System Design Guide N 5 y CH 1 IN CH 1 our y 3 J CH2IN CH 2 OUT 3 y 3 y CH 1 IN CH 1 OUT3 3 J CH 2 IN CH 2 OUT 3 ESE yi Jj ED QU QU CE OA EE A d 1 3 b 3 3 b D b D b D D D OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 6 7 8 9 OUT OUT OUT OUT OUT 10 OUT 11 OUT 12 OUT 13 OUT 14 OUT 15 OUT 16
22. a seamless algorithm that eliminates gating and its ill effects Gain is proportioned among all inputs assigned to each output channel in a seamless and continuous manner based upon microphone activity The algorithm incorpo rates an adaptive AutoSkew process to eliminate artifacts such as comb filtering and abrupt gating that occur with conventional automatic mixing schemes Audio from the far end of a conference participates in the local mixing algorithm just like a microphone in the local sound system Two digital acoustic echo cancellers are provided in the DMTH4 to further reduce the return of local signals to the far end One operates on the telco connection and the other is dedicated to the video codec connec tion In conjunction with the automixing process echoes are minimized and not heard at the far end ERL echo return loss refers to the natural attenuation of the far end audio signal as it circulates from the far end through loudspeakers and microphones in the local sound system and back to the far end Good design in the local sound system will reduce the acoustic cou pling between loudspeakers and microphones using physical placement and mix minus matrix routing Depending upon room size and acoustics it is often impossible to achieve adequate decoupling to avoid an echo heard by the far end during a teleconference Thus other types of processing are needed to further reduce the return echo ERLE ERLE echo retur
23. aS easy as using a standard mixer And by using this continuous gain modulation technique abrupt level changes and other anomalies normally generated by a switching or gating method are eliminated An additional feature of the Lectrosonics automatic mixing algorithm is an intelligent method of keeping track of which channel has been the loudest for the longest time period and skewing a priority toward that channel in the mix This AutoSkew process gives the priority channel up to 6dB of additional gain over the other channels making it appear to be more dominant in the gain sharing allocation The skewing rate is damped to avoid abrupt level changes that might be audible The AutoSkew algorithm also keeps non speech transient sounds coughs bumps clicks and pops from affecting the gain allocated by the auto mixing process For example if someone bumps an unused microphone while someone else is talking the gain of the micro phone in use will not change AutoSkew is especially important in sound systems where the talker may be in close proximity to more than one microphone For example in a boardroom where multiple microphones are placed next to one another along a table it is very common that a talker leans one direction or the other and is momentarily equidistant between two microphones If both microphones were open and mixed at the same level very audible comb filtering would occur Another example would be a
24. and an expensive problem DM Series matrix mixers combine the elegance of the LecNet2 automatic mixing algorithm combined with the feedback reduction and stability of Mix Minus This design architecture provides an outstanding foundation for sound systems to simultaneously provide reinforce ment teleconferencing and recording Mix Minus also reduces echoes heard at the far end of a teleconfer ence while full duplex operation is preserved MIX WITH MICS 1 2 3 4 MINUS MICS 5 AND 6 CH7 a t CH8 5 ais 8 o s LECTROSONICS INC Digital Matrix and DANI Bus The core of the DM Series processors consists of a digital matrix and a digital bus called DANI digital audio network interface The digital matrix is common to all units in a system The DANI bus interconnects the hardware to allow access to the matrix signal flow and transfer data required for automatic mixing functions In order to understand the power and functions available with this architecture it is helpful to think of them as entities separate from the hardware In this sense a DM processor is simply a hardware based tap into the digital matrix via the DANI bus to interface various types of microphones and audio equipment with the digital matrix Thus connected the processors distribute audio signals and share informa tion about each input and output to provide a myriad of features and functions When multiple DM processors are stacked each un
25. auto matic mixers seek to open only those microphones which are being spoken into at any given time Keeping the number of open microphones to a minimum reduces re circulated sound to improve intelligibility and eliminate acoustic feedback Automatic microphone mixers attenuate unused micro phones following the rule that the gain applied to all open microphones is distributed among them so that it is always equal to a single open microphone This process is commonly referrred to as NOM 1 or the Number of Open Microphones 1 Following this rule a sound system will perform the same with multiple microphones as it does with a single microphone with respect to feedback stability and intelligibility While all automatic mixers turn microphones on and off and implement some form of NOM attenuation they are not all equally effective The Lectrosonics automatic mixers employ a patented proportional gain algorithm to distribute gain across all channels in a seamless manner An overall reference level is created by sum ming all channels Then each individual channel is compared with the overall reference level and attenu ated by the difference between its level and the refer ence level The channels with the highest microphone signal levels thus receive proportionally higher gain than inactive or less active microphones NOM 1 attenuation along with an adaptive threshold is inherent in this algorithm As a result accurate setup 5
26. be assigned to a single pin The contact closure can then activate either the switcher or the pan tilt platform To smooth the switching activity the DM mixers provide programmable parameters for both input qualification time and hold time Qualification time is the time that 1 Active Talker triggers camera switch via DM1624 a A e K TAAN 24 L 77 22 P d lt PUSH FOR MENU SELECT DM1624 j LECTROSONICS 4 Video as Dura seen by Far end Video Conferencing Codec Video Switcher EA r Active Talker Lecnet Hosp mnm E 2 Direct Control by d the DM will withhold the notification of channel activity This helps prevent a switcher from triggering when someone coughs moves a paper bumps a microphone or some other momentary sound occurs The Hold time keeps the contact closed if the micro phone goes quiet to avoid losing the camera simply because someone pauses briefly Both parameters are adjustable from O to 25 5 seconds in 0 1 second increments to prevent false triggering or jumpiness in the video as it attempts to follow a conversation This leads to the other question before the designer whether to use multiple cameras or pan tilt platforms That often depends on the nature of the conferences For very large and or very active rooms where the conversation may be unstructured and free flowing using multiple cameras will work better Pan til
27. choose a macro number click OK At this point the macro is written to the DM mixer Click Done to close the Macro Editor In order to test the newly written Macro go to the Macro Editor menu and choose Run Macro Select the macro you would like to run by title and number choose Crosspoint 1 3 Click OK then go to the Matrix tab and the three crosspoints will now be enabled in the Matrix As an additional example create a second macro following the above instructions using the same xpgn commands except this time set them to 70 instead of 0 Give this macro a new name and Save it to macro 2 Run the new macro and all of the crosspoints will be disabled in the matrix 70dB is the equivalent of off There are now two macros created and saved that will do the opposite of each other toggle located in macros 1 and 2 in the DM mixer Assigning Macros to External Buttons To practice assigning our new macros to external SPST momentary switches Test button is provided in the DM mixer control panel that will simulate external switch contacts In the control panel choose the Rear Panel www lectrosonics com System Design Guide Ctrl tab Select programmable Input 1 it might be selected already as a default Assign the function to Run Macro on Close Macro 1 will appear with the title that you assigned to it Also the programmable input tab in the lower left now shows RMI this 15 simply a handy reminder that
28. d audio delivered by the local loudspeaker system When there is no sound or noise in the local room the DSP can do a decent job of identifying the far end audio and subtracting it from the transmitted signal but this is rarely the case in full duplex telecon ferencing LECTROSONICS INC In a simple sound system arrangement the local microphone can be muted when nobody is talking in the local room A simple gated mixer can provide this function With no open microphones locally there is obviously no return echo signal This requires that a threshold level be set high enough to keep the micro phone from being opened by background noise but low enough to allow it to open when someone speaks When the local microphone is open a return echo path is created which is when a DSP echo canceller is needed Given the wide variety of human voices and the dynamics of noise in a meeting room a gated mixer is often not the best choice Using a dedicated DSP echo canceller on each input of the local mixer referred to as distributed echo cancel lation is an expensive but effective approach to reducing the return echo The process requires the algorithm to converge which is to identify the far end audio and subtract it from the signal sent to the far end This requires at least a brief moment when there is very little local sound or noise with significant far end audio present in the room If nobody moves and there are no gain changes
29. e Boardrooms Training and Conference Centers Audio in Audio Out Video in Video out T1 CODEC LECNET2 RS 232 TRS 1 8 USB g H DANI BUS RX Ru45 DANI BUS RJ45 E EB ANI BUS RX Ru4s CODEC IN MIC LINE LEVEL AUX IN MIC LINE LEVEL CODEC OUT LINE LEVEL J AUX OUT LINE LEVEL HANDSET LINE TELCO LINE REMOTE PORT CODEC hA ll H REMOTE PORT POTS h DMTH4 Analog Control Port 25 pin d sub LECNET2 RS 232 TRS 1 8 LECNET2 USB DANIBUS RXRJ45 DANI BUS TX RU45 DANIBUS TXRJ45 DANI BUS RX RJ45 f DM1624 WIRELESS SEE Antenna i n1 Analog Control Ports WIRELESS 25 pin d sub Wireless mic Receiver WIRELESS EMPTY EMPTY EMPTY This diagram details a sound system appropriate for the boardroom or conference room The installation in cludes both audio and video teleconferencing which can be bridged for simultaneous 3 site conversations automatic recordings of these conferences tape input control systems and speaker zoning The DM1624 takes input and provides automixing from 12 wired microphones three wireless bodypack systems telephone lines via the DMTH4 and a hard disk media recording system In teleconferencing modes whether audio only or video the audio from the teleconference is recorded automatically Due to the low ceilings typically founding in board roo
30. e unit is much more than just a telephone interface Instead it is a complete DM Series digital matrix processor with a 3 in 24 out digital matrix 5 AS 4 5 3 15 AS 2 6 2 6 2 6 2 6 LECTROSONICS HOC ACI 22 0 4 0 8 0 8 0 8 0 B OUTPUT LEVEL STATUS ano automatic mixing and comprehensive signal processing on every input and output Two acoustic echo cancel lers are provided one dedicated to the CODEC and the other to the TEL connection An extremely fast echo cancellation algorithm converges so fast it tracks and adapts to the level changes in the auto mixing process which allows centralized echo cancellation CHS CH6 CH7 CH8 5 3 5 3 5 3 5 PAS B whe BR he POWER AMPLIFIER 1 d 7 T A a i a POWER OUTPUT LEVEL PAS The PA8 analog power amplifier provides 8 discrete channels for use in multi speaker sound systems It is fully protected from open and shorted outputs and thermal overheating Features include individual level A DMPA 12 LECTROSONIC bh d 12 CHANNEL POWER AMPLIFIER 0 0 0 0 0 0 0 0 0 7 20 A 7 7 n DI e e e AA oO OW 5 Lic controls on each channel depluggable input and output connectors passive cooling and a single rack space for installation in standard 19 racks Adjacent channels can be bridged for added power output LecNet 2 DSP a WIEN ER Cour 1 our 2 Jo
31. easily integrate with LecNet2 components with a powerful macro language added to further simplify programming and control options Lectrosonics remains an engineering driven company Ongoing efforts continuously produce new designs with the latest technology in electronics and mechanical engineering AMX is a registered trademark of AMX Corporation Crestror is registered trademark of Crestron Electronics Inc LECTROSONICS INC System Design Guide www lectrosonics com 27 581 Laser Hio Rancho NM 87124 505 892 4501 800 821 1121 505 892 6243 Fax www lectrosonics com sales O lectrosonics com 9 gt 9 o 00 LO ui y J i D Ls t CUJ IIN os A all LN 2 2 49 Suite 303A Toronto Ontario M5V 2J1 877 753 2876 or 877 7LECTRO Toll free 416 596 2202 416 596 6648 Fax June 2 2006
32. entralized echo canceller to address a variety of issues The automatic mixer provides seamless allocation of gain to local micro phones through a mix minus matrix to reduce back ground noise and decouple loudspeaker and micro phones while a very fast converging DSP echo cancel www lectrosonics com System Design Guide ler operates on the composite transmitted signal being sent to the far end This combination of processes is possible only with the latest DSP technology The auto mixing algorithm adapts to changes in back ground noise continuously and unlike a gated mixer there are no threshold levels to adjust A sum of all channels is the reference signal each channel level is compared to this reference and the individual channel gain is adjusted to apply NOM attenuation Gain is adjusted continuously to eliminate audible artifacts that gating and abrupt level changes can cause As the common mode noise in the room changes all channels are affected equally The end result is seamless adaptive auto mixing that requires no calibration or threshold adjustments Each individual output of the matrix operates as a separate NOM bus so a particular input can be as signed to multiple outputs with mix parameters adjusted differently for each output In other words gain and mix mode are configured independently for each matrix crosspoint resulting in great flexibility Four mix modes are supported Auto Direct Override and Backgrou
33. ges eliminators and a compressor Coarse Gain Fine Gain amp Polarity 0 18 Of LP HP BP Enable Disable x 0 5 t LO Every function and feature on e ouem 6 or 12 dB oct Attack TC Butterworth or Bessel Release TC every stage can be fully imple Input Gain amp Polarity ping id aii 5 Processing Sage the resources available Output Signal Processing Every output on every DM processor provides signal processing block to idealize the signal for sound rein Activity Indicator forcement recording media feeds or any other pur Gain Reduction Indicator pose The signal processing chain is Activity Indicator Level Meter especially useful in the DMPA12 digital power amplifier Back propa gated final mix signals from the Master unit in the system are indi Threshold Threshold O Gai vidually processed at the DMPA12 oA Eo e outputs so the same signal mix from ie A NU Attack TC Attack TC i dB steps the Master can be used for recording Butterworth or Bessel when applicable teleconferencing and sound rein Typical Output Processing Stages forcement varies slightly by model ADFE Automatic Digital Feedback Eliminator A special filter is included in the DSP stage at the inputs to eliminate acoustic feedback With the processor d LE CONDE setup and running a setup wizard provides a simple TEES OL en 1511 mm xj
34. he LCD on the DM1624 front panel will immediately reflect the new value of 7dB for channel 1 Creating Macros in LecNet2 There are several platforms usable to write and edit macros for LecNet2 device control Macros may be written line by line in the LecNet2 Command Terminal externally via a Windows or Mac based text editor like NotePad or in the Macro Editor found in the LecNet2 Control Panel For the Macro Editor within the DM Control Panel go to the Macros menu and select Macro Editor Give the Macro a name such as Crosspoint 1 3 and click in the single line field Commands to Execute As an example enable three crosspoints with the following set of instructions xpon l l 20 CR 2 2 0 lt CR gt 3 3 0 lt CR gt You have created a Macro titled Crosspoint 1 3 containing three commands which enable three crosspoints in the matrix The next step is to save the macro to the DM mixer While still in the Macro Editor go to the Device menu and select Store to device memory Enter 1 as the number for this macro normally you can choose a number between 1 through 128 If that macro location is empty the Title field will be blank If there is already a macro at that location the title associated with that number will display At that point either choose a new number or over write the old macro with the new one Do not try to type a title in this field it is for reference only Once you
35. he room and the microphones pick it up and return it to the far end The delay through this process creates an echo heard on the far end Local sound system Telephone Interface Local loudspeaker Local microphone There are several methods used to reduce or eliminate the echo heard on the far end of the conversation Optimal design in the sound system to minimize the coupling between loudspeakers and microphones e Mix minus matrix routing e Automatic microphone mixing e Digital acoustic echo cancelling Matters become more complex when the sound system is required to provide both teleconferencing and sound reinforcement A gain proportional automatic mixing process is widely recognized as the optimum solution for sound reinforcement but it places significant de mands on an acoustic echo canceller used for telecon ferencing The matrix mixer enables complex signal routing and level controls without limitations The matrix mixing allows mix minus zoning of microphones and loudspeakers to decouple them and reduce or eliminate acoustic feedback and echoes NOM attenuation is applied by the DSP at the crosspoints in the matrix which essentially provides 24 separate automatic mixers each with its own NOM mixing bus Four different mixing modes can be selected at the crosspoint for each input so each input can participate differently in each output mix The automatic mixing process uses
36. it participates with the digital structure in several ways Delivering audio signals from its input terminals into the forward propagated submix bus Passing back propagated final mix signals from the unit above it to the next unit below it Applying gain and signal processing to the audio signals at its input terminals Delivering audio signals to its output terminals as selected by the setup Applying signal processing to the signals routed to its output terminals Receiving and transmitting data required for the automatic mixing process in the matrix DM1624 DIGITAL AUTOMATIC MATRIX MIXER DSP System Design Guide The digital matrix is common to all processors in the stack with automatic mixing taking place at the crosspoints in the digital matrix The output of each crosspoint is then available at a variety of output terminals on various processors in the stack Different processor models interface with the digital matrix in different manners Audio signals and data are propagated from the Slaves to the Master unit in a stack then the data and some of the final mix signals in the Master are back propagated to the Slaves This provides additional final mix outputs at the output terminals on the Slave units Audio Frame Sync DM Series 1x Master Processor Quad RJ 45 Conn 24 2 Submix Mix Control x Digital Audio 12 2 Mix Mix Control DM Series 1x Network E Interface lt Slave Processor DANI
37. lticonductor wiring to the DB25 connector on the DM series units This control can be configured in the DM software to actuate virtually any function including but not limited to complete signal routing changes group or individual level controls on inputs or outputs or even change the nature of the automix functions LED s can be pro grammed independently from the buttons for status indicators or user feedback LECTROSONICS INC System Design Guide Example Sound System Designs Boardrooms Training Worship Center Automated and Conference Centers Sound Systems Worship Leader Music Leader VRS ever Congregation VRM Master channel 2 out Holds 1 6 Channel 4 Out VAS VAT Clanes Ou Antenna out 2 CH1 in CH 1 out NUITS Wireless mic Receiver CH2in CH 2 out VRS VRS CD RW RECORDER LECNET RS 232 TRS 1 8 Pastor LECNET USB Minister DANIBUS RX AJ45 DANI BUS TX RJ45 E DANIBUS TXRJAS DANI BUS AX RJS IN 1 OUT 1 OUT 2 IN 3 OUT 3 Pulpit Mic OUT 4 INS po CH 1 OUT l IN 6 Freeserve nessa m v JZ INT INS CH 2 OUT o CHT ot Analog Control Port CH 2 out 25 pin d sub cD PLAYER Altar Mic Aui GRP3 L Aux2 GRP2 R TAPEUO HARD DISK RECORDER WIRELESS Courtroom City Council Chamber uso
38. ms a mix minus speaker routing system is recom 16 in CH 4 in HARD DISK RECORDER mended Using the DM1624 matrix 16 speaker zones have been set up The DSP control within the DM1624 allows zone specific equalization and feedback control The 16 speaker zones are amplified with two amplifiers Control of the system can be achieved with an AMX or Crestron control system Programming can be easily altered on site by updating macros using the USB or RS232 ports and LecNet2 software The wireless microphone system is a Lectrosonics Venue receiver loaded with three VRS modules Bodypack transmitters can be LM SM UMAOO or by setting compatibility modes any transmitters from the previous 200 series LECTROSONICS INC Worship Center Automated Sound Systems Worship Leader Music Leader Antenna in 1 Antenna out 1 Congregation VRM USB port Antenna in 2 Wireless mic Receiver RECORDER Pastor Minister LECNET2 USB DANI BUS RX RJ45 DANI BUS TX RJ45 Pulpit Mic Je 000000000000 000000000000 Altar Mic Analog Control Port f 25 pin d sub aig Aux1 GRP1 GRP3 L Auo GRP2 GRP4 System Design Guide This diagram shows how the DM84 can be used as eliminates the need for routine microphone chasing automatic front end for the speech microphones in
39. n loss enhancement refers to addi tional circuits and processes used to further increase ERL Common methods are to use automatic mixing and digital echo cancellation Return Loss Enhancement The gain proportional automatic mixing algorithm in the DM Series processors not only provides seamless mixing for local sound reinforcement without abrupt gating but it also contributes significantly to ERLE The additional contribution is plotted in the following graph Contribution of the proportional gain algorithm to ERLE 45 T T T rt NEP T int 35 eed PH AT aid A ATE CCAA Qu ew eoo cocco cr ELRE dB ho in arte PEIPER COME A ewes T 5 10 15 20 25 30 35 40 ERL dB Digital echo cancellation is another method of reduc ing the echo delivered to the far end The concept described in very simple terms is to have the DSP recognize the far end audio and subtract it from the transmitted audio to remove any echo they might hear at the far end Sounds simple but in a sound system with multiple microphones and loudspeakers it is not easy to identify the far end audio in the complex mix of local sound local noise and the effects of the room on the far en
40. n of a typical City Council Cham ber including microphones for 16 council members podium tables and wireless systems Ample inputs are provided for various audio visual sources Multiple PA zones feed the main chambers along with the audience seating areas Press feeds are provided as is an output for an assistive listening system Any number of additional inputs can easily be added by expanding the system with one or more DM matrix mixers Up to 24 presets and 128 macros can be used CD Player R VCR Audio L DVD Audio R DVD Audio L Table Mic 4 Table Mic 3 Table Mic 2 Table Mic 1 Wireless Mic 2 Wireless Mic 1 Podium Mic 2 Podium Mic 1 Council Mic 1 Council Mic 2 Council Mic 3 Council Mic 4 Council Mic 5 Council Mic 6 Council Mic 7 Council Mic 8 Council Mic 9 Council Mic 10 Council Mic 11 Council Mic 12 Council Mic 13 Council Mic 14 Council Mic 15 Council Mic 16 for multiple setups and user scenarios www lectrosonics com LECNET2 RS 232 TRS 1 8 LECNET2 USB og 2 d og Control Ports 25 pin d sub Lo 5 pin d sub DANI BUS RJ45 DANI BUS RJ45 DANI BUS TXRJ45 DANI BUS RJ45 LECNET2 RS 232 TRS 1 8 LECNET2 USB DANI BUS RJ45 DANI BUS TX RJ45 H i H DANI BUS TXRJ45 DANI BUS RX RJ45 F3 Control Ports A Inp
41. nd The echo canceller converges continuously when the level of the far side signal exceeds a minimum level and the ratio of the far side signal to local room sound exceeds a minimum ratio This dynamic control prevents divergence during periods of silence from the far side room or in doubletalk situations The convergence takes place very quickly to keep up with the changes made by the automatic mixing algorithm and other changes that occur in the room Setup is greatly simplified and any adjustments such as level changes made with a remote control system are accommodated automatically The convergence speed is adjustable in the control panel GUI to fine tune it to a particular situation Faster convergence times can track changes in the room almost instantaneously but the depth of echo cancella tion will be reduced Slower convergence times take a bit longer to fully converge but produce greater echo cancellation The ERLE value achieved by the echo canceller is displayed on the GUI and the effects of altering the convergence rate will be immediately visible and audible An important final note on the is the fact that the echo canceller will never diverge lose conver gence This unique algorithm will also converge on a continuous sine wave which is especially important when DTMF tones are present in the room Since the echo canceller will never diverge there is no need for a panic button as is used in o
42. nents DMs4 LECTROSONICS 4 DIGITAL AUTOMATIC MATRIX MIXER DSP 0 9 9 0 0 0 7 0 A O A G 7 O n e e POE a 7 7 7 KD OW LecNet 2 DSP We Aen O n AZ In a NE n AZ n am B ow a 2 USB STATUS We DM84 The DM84 is an 8 in 4 out digital matrix mixer allowing every input to be routed to any or all outputs Automatic microphone mixing using a proportional gain algorithm allows for greatly increased intelligibility and gain before feedback Each input can incorporate up to 6 filter LECTROSONICS stages plus compressor ADFE and delay Each of the 4 outputs provides a digital delay up to 9 filters and a compressor limiter Front panel controls and indicators allow the DM84 to be used in a similar manner to the older AM8 and AM8 TC units PUSH FOR MENU SELECT LecNet 2 k DM8s12 DIGITAL AUTOMATIC MATRIX MIXER DSP amp POWER DM812 The DM812 is an 8 in 12 out digital matrix mixer allowing every input to be routed to any or all outputs Automatic microphone mixing using a proportional gain algorithm allows for greatly increased intelligibility and DM1612 LECTROSONICS DIGITAL AUTOMATIC MATRIX MIXER DSP DM1612 The DM1612 is a 16 in 12 out digital matrix mixer allowing every input to be routed to any or all outputs Automatic microphone mixing using a
43. nsisting of a streamlined command protocol that is human readable and transport neutral e Two high speed communication ports in every Lecnet2 device USB and RS 232 e Visual command monitor built into many LecNet2 devices e PC hosted Command Terminal program for easy testing and debugging e PC hosted Net Server program which allows control of LecNet2 devices over a network connection The command protocol is designed to be compatible with existing remote control platforms yet easy to program for LecNet2 includes helpful tools like the command terminal program which allows a human to communicate with a LecNet2 device interactively It is used to send commands and view the responses much like working at the command prompt of a computer Since the LecNet2 protocol has a clean human read able syntax the commands and responses are easy to understand and debug Incoming commands can also be viewed on the LCD screen of LecNet2 devices for troubleshooting purposes LecNet2 is a system with high visibility into the command protocol The nature of the LecNet2 protocol makes it transport neutral allowing it to be carried over a USB connec an RS 232 link or a network connection using the HyperText Transport Protocol HTTP This offers great flexibility in designing remote control applications LecNet2 devices ship with both an RS 232 port and a USB port with the operation of the Lecnet2 command protocol identical over each
44. o use For instance to set the input gain for channel 5 on a DM unit to OdB we might say Input gain of channel 5 equals OdB This is a simple understandable expres sion of the desired update However typing the above expression might become cumbersome if a large number of instructions were required in a LecNet2 application Thus the macro language is simplified to be quick to type and yet still easy to understand To create the actual instruction line first we abbreviate input gain to ingn and shorten channel 5 to simply 5 Thus we now have ingn 5 By adding the new gain value to the input channel the complete Update instruction is now 1ngn 5 0 Each instruction must then be followed with a carriage return notated as lt CR gt Query In order to get specific information from a DM mixer the Query instruction is used to request the specific value needed For instance to determine the output gain value of channel 22 the instruction would thus be outgni22 7 CR the CR represents Carriage Return This would return an OK followed by the value If the syntax of the query is not correct the ERROR message will be returned It is also possible to query all the channels with a single instruction by using the asterisk character a wild card Oubgn CR This would return OK 0 0 0 0 0 0 0 0 0 0 0 0 if all the output gain values were set to OdB and the DM mixer was either a DM812 or a
45. oint on units with VCA taps It is also used as an analog control on units with Program mable Input connections Fully clockwise no attenua tion is applied Full counter clockwise the level is either fully attenuated or is reduced to 15dB as determined by an internal jumper on the circuit board 14 PBA Remote Control for DMTH4 Digital Telephone Hybrid e LEDs for Connect and Privacy status Push button switches for remote volume control e Fits single gang conduit box e Connects to a DB 9 connector on the DMTH4 e 7 conductor wiring with screw terminals The RCW TEL provides the main operating controls for the DMTHA hybrid in a remote location The circuit board is mounted to a single gang wall plate Soft touch switches and highly visible LEDs provide simple intuitive operation and instant recognition of the status of the DMTH4 Two RCW TELs would be used if the DMTH4 is connected to both an analog line and a codec This allows inde pendent control of both sources during a bridged three way room video audio conference Hemote control for DM Series products e 4 Momentary contacts e 4 Indicator LEDs e 8 Conductor wiring with screw terminals e Fits single gang conduit box e Four customizable function labels The RCW PBA is designed to provide remote control capability with any DM Series product by actuating macros presets or level controls The RCW PB4 connects via any small gauge mu
46. other for cluster or central loudspeaker systems in larger spaces lower illustration Values are entered into the data entry cells for distances between microphone talker loudspeakers and listeners and the targeted SPL at the listener s ears is selected Performance Meter Ld Prrrrrrrrrrrrr www lectrosonics com System Design Guide 1 Calculator A performance meter is also provided that indicates an approximation of how well the system would work with the given values The meter updates continuously as the different values are entered The program is a very valuable aid early in the design phase of a sound system project in determining the placement and quantity of loudspeakers and microphones ao LecNet2e Introduction to Writing Macros for LecNet2 One of the most powerful features of the new DM Series matrix mixers is the macro scripting language The DM Series products contain 128 global macros furthermore each macro can hold up to 64 serial commands If needed macros can be chained if a long sequence of commands is required There are three types of instructions that can be contained in a macro Query Update or Command A Query will always have a question mark and an Update will always have an equal sign 2 The Command will have neither a question mark nor an equal sign In General The syntax used for LecNet2 instructions closely follows natural English in order to make it easy t
47. struction is simply recall 1 lt CR gt Notice that neither a question mark nor an equal sign are present Similarly the instruction invoking macro 17 would be run 17 lt gt LecNet Command Terminal The LecNet2 command language has many types of instructions that are fully documented with examples in the User Manual and also in the Help section of the control panel of all LecNet2 devices A good way to become familiar with these instruction sets is to run the LecNet2 Command Terminal found in the LecNet2 software interface Once the Command Terminal has loaded and the DM device is connected via USB or RS232 type lt gt The DM device will respond with OK Xs represent 1624 1612 812 or 84 With this done it is possible to type in any of the docu mented instructions and view the real time changes in the LCD on the front panel certain DM Series devices For example power on a DM1624 mixer and make sure itis connected to your PC After the front panel shows DM1624 by Lectrosonics push the Menu Select rotary control and then select Setup Push Menu Select again and now select Inputs Next push Menu Select once more to arrive at the Input Setup screen for channel 1 Push the soft key below Gai Now the input gain for channel 1 can be monitored in real time LECTROSONICS INC Go back to the LecNet2 Command Terminal and type the instruction ingn 1 7 lt gt T
48. system can provide teleconfer encing sound reinforcement and multiple mixes for recording all at the same time LecNet2 components will operate as stand alone devices or as part of a larger integrated system in order to provide a multitude of functions in simple to use cost effective rack mounted assemblies USB and RS 232 compatible interfaces allow connec tion with all LecNet2 components providing the sup plied control software to communicate with each component Individual function settings and signal routing can be customized for a particular application during setup recalled from various screens during operation or recalled by other brands of remote control systems The LecNet2 serial port is completely compat ible with control systems from AMX Crestron and any other equipment with RS232 interface compatibility In addition a DANI Digital Audio Network Interface is provided so that the digital audio outputs of the master and slave units can be connected in stacked configuratons for larger applications LecNet2 Remote Control There is much more to the story than the hardware From the start we wanted to outfit these new products with a truly simple robust and flexible remote control capability The goal was to make life easier for third party control developers and let them focus on design ing great control applications rather than wrestling with the underlying protocols The result is the LecNet2 Control System co
49. t 1 to run Macro 2 the next time the button is pressed Next modify Macro 2 with the code prgindef 1 14 1 lt CR gt This will re assign programmable input number 1 to run Macro 1 during the next time it is used We now have a button that toggles between two Macros Just as we modified Macro 1 above go to macro 2 and add the line prgindef 1 14 1 lt CR gt Save this change as before To confirm that the single button toggles between the two macros each time it is pressed push the Test button for programmable input 1 Notice that it re assigned itself to run Macro 2 Press the Test button again it now has re assigned itself to run Macro 1 After each button press check the matrix and watch the toggle take place With this information it should be clear how much power and control is available in the DM series of DSP matrix processors with very simple instructions and macros 25 LecNet2e A Brief History of Product Development Founded in 1971 Lectrosonics began with the manufacture of portable sound systems sold under the Voice Projector registered trademark The first product line consisted of a contained lectern sound system and two over the shoulder portable sound systems In 1975 the first wireless microphone systems were introduced to audio visual markets The first system was a lavalier system consisting of a belt pack transmitter and matching receiver with narrowband IF filters called
50. t plat forms while reducing the number of cameras fail to travel quickly enough during a lively discussion to offer easy tracking of the video to the audio Given the lower costs of cameras compared to pan tilt mechanisms the multiple camera design makes better sense in many cases used in a smaller room or where the order of conversation is more structured for example Roberts Rules of Order in a council chamber then a pan tilt design can offer smooth transitions from one micro phone location to the next emulating the movement of one s head if they were observing the dialogue Please Note Automated switching works best with systems of 5 or more microphones 3 Camera Picks up Single Camera View 9 DM1624 OR Optional Control System for switching Video Follow Audio LECTROSONICS INC System Design Guide DSP Features and Setup GUI All models in the DM Series provide extensive digital signal processing to optimize each audio channel for its intended purpose in the system Indicator Indicator Activity Indicator Clipping Detector Input Signal Processing oignal flow for each input is shown in this diagram Following the input preamp and level control are the processing stages for delay six filter stages six ADFE feedback Gain Reduction Indicator Compressor Filters n Level Meter Six Filter Sta
51. tability Margin compensation FSM compensation will subtract 6dB from the calculated PAG value to give a more realistic indication of PAG More explanation of what can be done to maximize PAG can be found in the GAINCALC Help file What About Loudspeaker Power After the NAG and PAG calculations have been made its helpful to known how much amplifier power will be needed to produce the desired sound system SPL GAINCALC uses the sensitivity data of the system loudspeaker s the distance between the distant listener and the closest loudspeaker and the desired SPL at the distant listener s position to calculate the needed amplifier power Note that GAINCALC adds 20dB to the desired SPL factor Lr in order to account for peak speech levels without clipping One result of this is that if you require high SPL at the distant listener s position you ll find yourself needing enormous amounts of amplifier power In order to make a power calculation you should fill in the boxes labeled Spr Sens db Power O Distance of Speakers Lr and D2 The formula for the power calculation is Power of speakers x10a Where a Lr 20 SpkrSens 20xLog SpkrDist D2 10 LECTROSONICS INC LECTROSONICS j Performance Meter Tr PAG NAG Software GUI The program operates in two different scenarios one for multiple loudspeaker systems such as in a board room upper illustration and the
52. tems continued with the introduction of an encrypted digital system in early 2003 following several years of R amp D Introduced as the 700 Series with a 19 half rack diversity receiver belt pack and hand held transmitters the system is presently in use by a variety of security conscious private companies in addition to several federal government departments In 1989 the first automatic mixer products were introduced in a modular configuration called the Modular Audio Processor This was a card cage design that held up to ten input or signal processing cards allowing the customization needed for medium to large scale sound systems in courtrooms boardrooms council chambers conferencing lecture halls and worship centers Numerous signal processing modules were added to this product group over the next five or six years As the popularity of automatic sound systems continued to grow and competition grew more fierce the appeal of microprocessor control turned into necessity leading to the first LecNet components in late 1994 ee LecNet was launched In December 1994 as the second generation of audio products to address an increasing demand for fully automatic sound systems in courtrooms lecture halls council chambers teleconferencing and distance learning applications LecNet components communicated with each other via on board microprocessors with a host PC used for setup and monitoring The automatic mixers in this group u
53. ther designs to generate a noise burst to help the echo canceller re converge LecNet2e Video Follow Audio A Practical Primer As teleconferencing advances and becomes more common new design requirements have risen that can be addressed with the DM Series In a large room a single camera can only deliver an image of the entire table leaving the far side viewers to guess which of the little talking heads in the picture is actually speaking Video follow audio methods allow the video signal to track the audio conversation This is done via two possible control methods pan tilt cameras or multiple cameras through a video switcher To do so requires a signal from the automatic mixer that lets the camera control system know to which zone to bring the camera The DM Series mixers have two ways of providing this data If controlling the system through a third party device the control system can acquire the information via the serial port The programmer codes a looped inquiry that constantly polls the mixer for the status on the various microphones When the microphone comes to within 6dB of full gain the control system is notified via the serial port and either switches to the correct camera or calls up the new pan tilt coordinates The second and sometimes simpler method is to set the programmable outputs of the DM Series to emulate a contact closure upon activity at any given set of microphones Entire groups of microphones can
54. tilized a patented Adaptive Proportional Gain Algorithm to apply NOM attenuation without switching and to prevent background noise from affecting the mixing action The LecNet family grew from the first stand alone automatic microphone mixer to larger automatic matrix mixers multi channel DSP processors a digital telephone hybrid an 8 channel power amplifier and a variety of accessories and remote controls In November 2004 the first shipments of LecNet2 DM Series digital matrix processors took place Three models were offered 16in 24 out 16in 120ut and 8in 12out In addition to a digital crosspoint matrix a DANI digital audio network interface bus was introduced This fully digital bus allowed audio and control signals to flow upward from slave to master units then return from the master unit backward to the slaves This new concept called back propogation expanded the flexibility and signal routing cabability beyond the earlier analog designs Extensive signal processing was also available on every input and output The DMTH4 digital telephone hybrid was added in early 2006 followed by the DMPA12 a 12 channel digital power amplifier that tied directly into the DANI bus via CAT 5 connections on the rear panel The DM84 model was introduced in June 2006 to replace the earlier analog models with 8 inputs Extensive control flexibility of LecNet2 components was built into the basic architecture AMX and Crestron control systems
55. ur our mm Cour oe a M our Se 10 Sou 12 move USB STATUS POWER qae DMPA12 The 12 is a digital 12 channel power amplifier and DSP processor in a single 19 rack enclosure Audio inputs are taken from the final mix signals back propagated via the DANI bus from the Master in the system These final mix signals are then processed vm VENUE RECEIVER LECTROSONICS wy Venue Wireless Microphone Receiver The Venue Receiver system is a modular UHF design that operates with Digital Hybrid Wireless transmit ters and a variety of analog transmitters It consists of a Venue Receiver Master VRM and one to six plug in receiver modules The VRM includes an antenna multi www lectrosonics com individually at each output channel in the power ampli fier to apply digital delay equalization filters compres sion and limiting The unit runs very cool with 10 Watts per channel using Class D amplifiers and passive cooling no fan PUSH FOR MENU SELECT qu PHONES Digital Hybrid Wireless coupler computer communications interface and the mechanical rack mounting for the receiver modules Supplied software allows the Venue receiver to be addressed via RS232 or USB as part of a LecNet2 audio system 13 LecNet2e Wired Remote Controls DMTHA vw TEL Connects directly to the Remote Control Port DB 9 on the DMTH4 e Brings the hybrid front
56. uts System Design Guide Audience Zone 4 Audience Zone 3 Audience Zone 2 Audience Zone 1 PA Zone 4 Zone 3 PA Zone 2 PA Zone 1 18 LecNet2e Multi Room Combining Lond Su A A lod a Y d O 0 LECNET2 RS 232 TRS 1 8 LECNET2 USB DANI BUS RX Pu45 DANI BUS RJ45 EN EE DANI BUS TXRJ45 DANIBUS RX RJ45 fi E i o Analog Control Port 25 pin d sub This four room combining system features one micro phone and one auxiliary input per room The DM84 provides the automatic mixing function while the DMPA12 amplifier feeds each of the 12 loudspeakers Control of the system is via an analog control panel either in one of the rooms or located elsewhere Automatic mixing and NOM attenuation is preserved in each room Background music can be individually selected and paging signals can receive priority over local sources 20 o LECNET2 RS 232 TRS 1 8 LECNET2 USB DANI BUS RX Ru45 12 _ FS DANI BUS TX RJ45 DANI BUS RJ45 DANI BUS RJ45 Analog Control Port 25 pin d su Analog Remote
57. worship center where a person using a wireless lapel microphone approaches a gooseneck podium micro phone and the voice is picked up equally in both microphones AutoSkew reduces or eliminates comb filtering by not allowing any two or more channels to be mixed at the same level Sound level at the microphones Sound level at the microphones 20 20 20 20 20 20 20 10 10 10 10 10 10 10 0 0 0 0 0 0 0 AutoSkew increases the Proportional Gain Allocation with Adaptive Skewing dominance of the most active 20 20 20 Conventional Proportional Gain Allocation microphone channel 0 0 0 Relative channel levels at thegnixer output US Patent 5 414 776 www lectrosonics com 5 LecNet2e Mix Minus Loudspeaker Zoning Sound reinforcement systems installed in rooms with low ceilings often use multiple ceiling mounted speak ers distributed throughout the room in order to provide even coverage When multiple microphones are used as in a conference room achieving any significant sound system gain before feedback can be difficult Since system microphones will almost always be in the direct sound field of one or more of the distributed loudspeakers feedback is virtually assured Automatic mixers help the situation by minimizing the number of open microphones Even with an automatic mixer however there may still be a need for some form of loudspeaker control in order to get acceptable GBF
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