Electro-Voice MTL-2BT User's Manual
Contents
1. both with and without equalization and crossover filters on axis in the farfield in an anechoic environment using a swept sine wave siynal When measured with an electronics the Dx34 digital electronic unit was used to provide the necessary crossover filters and equalization With the crossover in place a high pass protection filter was applied to the low end of the low frequency section One watt of power 2 00 voits rms at 70 Hz was applied to the midband of the low frequency section The sound pressure level was normal ized for an equivalent one meter distance DIRECTIVITY The directional response of the MTL 2BT was measured in an anechoic environment at a distance of 6 1 meters 20 feet using 1 3 octave filtered pink noise A full spherical mea surementsystem was used The polar response of the loudspeaker system at selected 1 3 octave frequencies is shown in Figure 3 The frequencies selected are fully representative of the polar response of the system The beam width of the system utilizing the complete 1 3 octave polar data is shown in Figure 4 The Directivity Factor Q R and Directivity Index D are shown in Figure 5 Complete AcoustaCADD data is available for the MTL 2BT loudspeaker system DISTORTION Distortion for the MTL 2BT shown in Figure 6 was measured on axis in the farfield in an anechoic environment ata level of 0 1 times the full power rating 120 watts as per the AES standard The sound2. bottom the woofers i e cause the voice coils to strike the back plate which can result in damage to the speakers Even if bottoming does not occur the subpassband signals waste amplifier power cause undue mechanical stress on the speakers and result in high levels of loudspeaker distortion USE IN MULTIPLES MTL 2BT systems may be used in multiples to increase acoustic output When two loudspeaker systems are placed side by side a 6 dB in crease in maximum acoustic output power is possible at low frequencies assuming all woof ers are operating with the same polarity This increase occurs because at low frequencies the woofer cones from the two systems mutu ally couple acting as a single cone with twice the area and therefore twice the efficiency providing a 3 dB increase in sound pressure level The second 3 dB comes from the dou bling of the power capacity by adding a second system Mutual coupling occurs when the cen ter to center spacing between the two loud speaker systems is approximately one half wavelength orless When the spacingis greater than one half wavelength as would occur if two systems were widely spaced the maximum acoustic power output increase is limited to the 3 dB power handling increase Additional sound pressure level can also occur from the increased directivity that results when multiple systems are closely arrayed together If two systems are placed side by side the beamwidth of th
3. certain specific items described in the individual product line statement s below or in the individual product data sheet or owner s manual malfunction resulting from use or operation of the product other than as specified in the product data sheet or owner s manual d malfunction re sulting from misuse or abuse of the product or malfunction occurring at any time after re pairs have been made to the product by anyone other than Electro Voice or any of its authorized service representatives Obtaining Warranty Service To obtain warranty service a cus tomer must deliver the product prepaid to Electro Voice or any of its authorized service representatives together with proof of purchase of the product in the form of a bill of sale or receipted invoice A list of authorized service reprcseniatives is available from Electro Voice at 600 Cecil Street Buchanan 49107 616 695 6831 or 800 234 6831 Incidental and Consequential Damages Excluded Product repair or replacement and retum to the cus tomer are the only remedies provided to the customer Electro Voice shall not be liable for any incidental or consequential damages in cluding without limitation injury to persons or property or loss of use Some states do not allow the exclusion or limitation of incidental or consequential damages so the above limitation or exclusion may not apply to you Other Rights This warranty gives you specific legal rights ard you may
4. also have other rights which vary from state to state Electro Voice Speakers and Speaker Sys tems are guaranteed against malfunction due to defects in materials or workmanship for a period of five 5 years from the date of original purchase The Limited Warranty does not apply to burned voice coils or malfunctions such as cone and or coil damage resulting from improp erly designed enclosures Electro Voice active electronics associated with the speaker sys tems are guaranteed for three 3 years from the date of origina purchase Additional details are included in the Uniform Limited Warranty statement Electro Voice Flying Hardware including en closure mounted hardware and rigging acces sories is guaranteed against malfunction due to defects in materials or workmanship for a period of one 1 year from the date of originai purchase Additional details are included in the Uniform Limited Warranty statement Electro Voice Accessories are guaranteed against malfunction due to defects in materials or workmanship tor a period of one 1 year from the date of original purchase Additional details are included in the Uniform Limited Warranty statement Service and repair address for this product Electro Voice Inc 600 Cecil Street Buchanan Michigan 49107 616 695 6831 or 800 234 6831 Specifications subject to change without notice ELECTRO VOICE MARK IV Manca Street Melton 49107 MANUFACTUR
5. daisy chained together as long as the safety factor is 5 1 or greater and local regula tions are met Electro Voice offers a line of flying hardware accessories for use with the MT loudspeaker systems CAUTION The MT loudspeaker systems should be suspended overhead only in ac cordance with the procedures and limita tions specified in the MT Flying Manual and manual update notices FIELD SERVICE In the unlikely event that the MTL 2B should require service the 18 inch woofers can be accessed from the front of the enclosure by removing the grille using a 2 Phillips screw driver The woofers can be unbolted using a 5 32 inch hex key wrench and slid straight out of the manifold chamber There is a wiring diagram label for the system located on the underside of the input panel As a further ser vice convenience a hardware kit that includes a 5 32 inch hex key and an assortment of spare screws and washers are included with every MTL 4B oudspeaker system A woofer failure will require the entire driver to be returned to an authorized Electro Voice service center for repair The following parts are available from the Electro Voice Service Department in Buchanan Michigan MTL 2BT Service Data Sheet 534488 LF 818 2389 EVX 180A Complete Driver ARCHITECTS AND ENGINEER S SPECIFICATIONS The loudspeaker system shall be a low fre quency system and shall operate from 37 200 Hz with a sensitivity of 99 5 dB for one watt at o
6. Electro Voice SHOWN WITHOUT GRILLE SPECIFICATIONS Frequency Response measured in farfield calculated to one meter on axis swept sine wave one watt input into LF midband anechoic environment see Figure 1 37 200 Hz Low Frequency 3 dB Down Point 45 Hz Usable Low Frequency Limit 10 dB down point 35 Hz Half Space Reference Efficiency 6 0 Long Term Average Power Handling Capacity per ANSI EIA 426 1980 see Power Handling Section 1 200 watts Maximum Long Term Average Midband Acoustic Output 72 watts Sensitivity SPL at one meter indicated input power anechoic environment band limited pink noise signal 1 Watt 99 5 dB 1 200 Watts 130 5 dB Beamwidth angle included by 6 dB down points on polar responses indicated one third octave bands of pink noise see Figures 3 and 4 80 to 160 Hz Horizontal 260 80 50 80 to 160 Hz Vertical 225 85 35 Directivity Factor R Q 63 to 100 Hz Median see Figure 5 2 17 0 19 0 33 Directivity Index D 80 to 160 Hz Median see Figure 5 3 36 dB 0 37 dB 0 71 dB Distortion 0 1 Full Power Input see Figure 6 Second Harmonic 50 Hz 2 0 100 Hz 1 3 Third Harmonic 50 Hz 1 2 100 Hz lt 0 1 Transducer Complement Two EVX 180A Box Tuning Frequency 37 Hz Impedance LF1 and LF paralleled see Figures 2 amp 7 Nominal 4 ohms Minimum 3 6 ohms input Connections Neutrik Speakon NL4MPR En
7. ING PLANTS BUCHANAN NEWPORT TN SEVIERVILLE TN OKLAHOMA CITY OK GANANOQUE ONT 1995 Litho in U S A Part Number 532449 9503
8. and MTH 2 94B systems combined that utilize Linkwitz Riley 24 dB per octave cross over filters at 160 and 1 600 Hz Each output section has equalization specifically matched to the loudspeaker system and time delay set to achieve zero lobing error and time alignment between frequency bands In addition the out put levels of each frequency band are set so that with the output level controls set the zero dB position the loudspeaker system will have a flat frequency response in an anechoic envi ronment when used with amplifiers having iden tical gain ELECTRICAL CONNECTION AND SYSTEM WIRING Electrical connections to the MTL 2BT are made on the back of the enclosure via a 4 pin connec tor There are two connectors on the input panel to allow paralleling of other MTL 2BT systems The Neutrik Speakon NL4MPR is used for both connections One mating Neutrik Spea kon NL4FC cable end connector is supplied with each loudspeaker system The pin assign ments are as follows Pin 1 LF1 Pin 2 LF2 Pin 1 LF1 Pin 2 LF2 The MTL 2BT has two 8 ohm woofers with one connected to Pins 1 1 and the other to Pins 2 2 A wiring diagram of the loudspeaker system is shown in Figure 7 The electrical impedance versus frequency is shown in Figure 2 FLYING THE MT SYSTEMS A manual entitled the MT Flying Manual is available from Electro Voice and is included with each flying MT loudspeaker system A brief intro
9. closure Materials 14 ply birch plywood Finish Black carpet Hanging Two point flying system tracks accept Kinedyne 32102 1 and 32111 1 fittings Dimensions Height 91 4 cm 36 00 in Width at Front 57 2 cm 22 50 in Width at Back 28 3 11 13 Depth 75 9 cm 29 88 in Side Angles 15 each 30 wedge Net Weight 69 9 kg 154 Ib Shipping Weight 74 8 kg 165 Ib DESCRIPTION The Electro Voice MTL 2BT low frequency loud speaker system is a member of the family of Manifold Technology MT loudspeaker sys tems designed for high level sound reinforce MTL 2BT Manifold Technology Low Frequency Sound Reinforcement System EVX 180A woofers for explosive impact reliable bass Smaller MT trapezoidal enclosure High acoustic output low distortion Manifold Technology enables smaller and lighter loudspeaker arrays MT systems with different coverage patterns and output capabilities may be mixed and matched Unique rigging scheme for flexible array design and quick assembly Available without rigging hardware ment in concert sound touring and permanent installation applications The MTL 2BT is a manifolded vented box low frequency system with a trapezoidal enclosure utilizing two very high power 18 inch woofers This configuration results in remarkably high acoustic output from a small enclosure The MTL 2BT may be com bined with other members of the MT 2B and MT 4B loudspeake
10. ductory overview is included here The MT Flying Manual should be consulted for com plete structural specifications and detailed in formation on safely suspending and using the MT systems The MTL 2BTCF carpeted is the version of the MTL 2BT loudspeaker system that includes flying hardware The MT systems incorporate a unique two point flying system that permits a wide range of vertical angle adjustment and offers maximum flexibility in array design and implementation for both touring sound and per manent installations The quick release air craft L track type hardware design allows ar rays of loudspeakers to be assembled and disassembled very quickly and offers such flexibility in the vertical angling of cabinets that pull up points are usually unnecessary Fur thermore all of the flying MT 2B and MT 4B loudspeaker models include the same rigging hardware allowing the different models to be mixed as necessary throughout an array The rigging track accepts Kinedyne 32102 1 and 32111 1 type double stud ring fittings In dividual rigging points have typical break strength ratings of 3 750 4 000 pounds which EY Electro Voice Inc translates to working load ratings of 750 800 pounds for a 5 1 safety factor Consult the MT Flying Manual for specific structural strength ratings and limitations The enclosures may be oriented with the rigging track on the sides of the enclosure or on the top and bottom and may be
11. e combined systems at low frequencies will be approximately one half the beamwidth of a single system in the plane that they are arrayed Adding additional systems will reduce the beamwidth further at low fre quencies Systems can be arrayed both hori zontally and vertically to increase directionality in both planes LOUDSPEAKER LOCATION Low frequency loudspeaker systems such as the MTL 2BT are often located on the floor or close to walls This is often convenient and provides additional acoustic loading toincrease the low frequency officiency of the system Because there is typically little directional infor mation present in program material below 125 Hz the audible location of the low frequency loudspeaker systems will not be particularly evident with those systems located on the floor separated from the higher frequency systems positioned overhead for the desired locational cues and uniform audience coverage Other situations however may benefit from having the low frequency systems suspended overhead along with the higher frequency sys tems Floor space may be limited or sightlines may be a problem on the main floor seating area requiring low frequency systems to be suspended overhead higher crossover fre quencies or program material with low frequency locational cues may require may require the low frequency systems to be located near the higher frequency systems or a particular geo metric layout of a venue and so
12. igns The MTL 2BT may be combined with other members of the MT 2B and MT 4B loudspeaker family provid ing the array designer a variety of coverage angles acoustic output and enclosure sizes from which to choose For full range applica tions the MTL 2BT may be combined with the MTH 2B or MTH 4B midbass mid frequency high frequency loudspeaker systems The MTH 2 64BT system has a trapezoidal enclo sure that is dimensionally identical to the MTL 2BT For maximum acoustic performance of the MT loudspeaker systems the Electro Voice 0 34 digital electronic crossover equalization time delay limiter unit is recommended Careful attention was paid to details to provide both the touring company and sound contractor a convenient and timesaving sound reinforce ment package The MT 2B dimensions were chosen for efficient truck pack and high density array design The systems may be stacked four high and three wide or three high and four wide in a standard truck box enabling 12 000 watts of sound system to be accommodated in only three feet of truck floor length The two point rigging system offers flexible array design and efficient assembly To facilitate service a variety of screws washers and hex key wrenches are provided with each loudspeaker system In addition there are wiring diagram labels in convenient locations inside the sure FREQUENCY RESPONSE The MTL 2BT frequency response shown in Figure 1 was measured
13. ne meter The system shall consist of two 18 inch woofers manifolded at the center of a vented box enclosure have a total input im pedance of 4 ohms and have a power rating of 1 200 watts as per ANSI EIA 426 A The loud speaker system shall have a trapezoidal sure with 15 angled sides forming a30 wedge shall be constructed from 0 75 inch thick 14 ply birch plywood shall be finished with a black carpet shall have a black nylon grille and shall have a two point rigging system that will accept 32102 1 or 3211 1 1 type double stud ring fittings if applicable The loudspeaker enclosure shall be 36 00 inches high 22 50 inches wide at the front 11 13 inches wide at the back and 29 88 inches deep and shall weigh 154 pounds The loudspeaker system shall be the Electro Voice MTL 2BT MTL 2BTCF or MTL 2BTC UNIFORM LIMITED WARRANTY Electro Voice products are guaranteed against malfunction due to defects in materials or work manship for a specified period as noted in the individual product line statement s below orin the individual product data sheet or owner s manual beginning with the date of original purchase If such malfunction occurs during the specified period the product will be repaired or replaced at our option without charge The product will be returned to the customer pre paid Exclusions and Limitations The Lim ited Warranty does not apply to a exterior finish or appearance b
14. ntaneous power peaks 2 SPECIFICATION GRAPHICS TERMINAL 15 RED TERMINAL 15 BLACK i 4 5H 5 ee e i 424 Hm 3 lt P a apuaan 5 w e e 3 3 HORIZONTAL FIGURE 1 Axial Frequency Response FIGURE 3 Polar Response 3 Taur All versions of the MTL 2BT are constructed of 0 75 inch thick 14 ply birch plywood and ex tremely well braced to survive the rigors of the road The MTL 2BTCF flying and MTL 2BTC non flying systems are covered with black Ozite Super TNT carpeting the most rugged in the industry The MTL 2BTCF system incorpo rates a unique two point flying system All mod els feature a black nylon cloth grille APPLICATIONS The MTL 2BT is ideal for any professional concert sound touring or permanent installa tion application requiring high sound pressure levels at low frequencies with low distortion from a compact enclosure The Manifold Tech nology design maximizes the acoustic output per enclosure frontal area acoustic output per enclosure bulk volume and acoustic output per enclosure weight of the loudspeaker system This enables loudspeaker arrays to be con structed that are significantly smaller and lighter than would be obtainable with conventional loudspeaker system des
15. pressure level was nor malized for an equivalent one meter distance Plots of second and third harmonic distortion are shown referenced to the fundamental POWER HANDLING CAPACITY Electro Voice components and systems are manufactured to exacting standards to ensure reliability in continuous use in arduous real life conditions Besides utilizing industry standard power tests extreme in house power tests which push the performance boundaries of the loudspeakers are also performed for an extra measure of reliability The MT systems are rated as per the ANSI EIA 426 A Loudspeaker Power Rating Full Range Test which uses a shaped random noise signal to simulate typi cal music to test the mechanical and thermal capabilities of the loudspeakers Specifically the MTL 4B passes the ANSI EIA 426 A power test with the following test parameters LF Section LF1 amp LF2 paralleled 1 200 watts total Test Voltages 58 7 volts rms 117 4 volts peak Ry 1 15 x R 2 88 ohms each input SUBPASSBAND SPEAKER PROTECTION Below the enclosure tuning frequency cone excursion increases rapidly with little increase in acoustic output Itis therefore highly recom mended that a high pass ilter be used to pro tect the system against subpassband signals A high pass filter 3 dB down at 32 Hz with a minimum slope of 12 dB per octave is sufficient to provide adequate protection for the MTL 2BT Without protection subpassband signals may
16. r family The combination of the MTL 2BT loudspeaker system and the MTH 2B midbass mid frequency high frequency loudspeaker systems form the MT 2B full range system There are two models in the MTL 2BT series the MTL 2BTCF carpeted finish with flying hardware and the MTL 2BTC carpeted finish without flying hardware The MTL 2BT is a vented box design com prised of two EVX 180A 18 inch woofers each facing into a manifold chamber at the center of the enclosure This manifolding technique U S Patent No 4 733 749 results in increased acoustic loading yielding increased low fre quency efficiency and reduced distortion over conventional direct radiating designs in a re markably small enclosure The MTL 2BT is typically 2 3 dB more efficient than horn loaded enclosures of equivalent size in the 40 80 Hz range Additionally by having the motor struc ture on the outside of the enclosure this radical design allows for efficient heat transfer from the loudspeakers to minimize thermal build up dur ing extended periods of high power operation The EVX 180A was designed to deliver the highest possible low frequency output and is ideal for manifolding in the MTL 2BT enclosure Its extended 4 inch diameter voice coil design assures linear low distortion output at extremely high power levels while its robust mechanical design is capable of withstanding the high acoustic pressures developed in the manifold chamber during explosive insta
17. und system may require low frequency systems to be suspended overhead foreven coverage inthese instances it may be possible to regain much of the effi ciency lost by removing the low frequency sys tems from the floor by closely spacing the systems to increase the mutual coupling and by constructing the low frequency array in a manner that increases the low frequency direc tivity CROSSOVER EQ AND TIME DELAY The usable frequency range of the MTL 2BT low frequency loudspeaker system is 32 200 Hz A crossover frequency of 160 Hz with 24 dB per octave slopes is recommended For full range applications one of the MTH 2B midbass mid frequency high frequency loud speaker systems is recommended for use with the MTL 2BT For optimal acoustic performance the Electro Voice Dx34 digital electronic cross over equalization time delay unit is recom mended The 0x34 is a programmable two in four out digital electronic unit which may be configured for stereo two way mono three way plus sub woofer or mono four way operation Each out put section includes crossover filters equaliza tion limiting ime delay polarity and gain ad justment the parameters of which all may be programmed and stored by the user In the mono four way configuration the Dx34 in cludes factory presets for optimal performance of the MT 2 64B loudspeaker system the MTL 2BT and MTH 2 64BT systems combined and the MT 2 94B loudspeaker system the MTL 2BT
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