EMT-240-rev-sm维修电路原理图.pdf

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1、Instruction ManualEMT 240Reverb FoilGERMANYBARCO-EMTCONTACT: BIRDGETTE HEBDING nee (ZIMMER)TELEPHONE: 0114978259060RadioFans.CN 收音机爱 好者资料库ATTENTION!The unit contains an additional protection against shock, in order toprevent any damages caused by shock or other impacts due to rough handlingin transi

2、t.Before operation please remove the shock protection in the following se-quence:Open one side of the housing - take the wrench of the accessories andloosen nuts at the lower wooden blocks until the bolts will release theinside housing - take of f laterally the squeezed upper blocks - take offlatera

3、lly the lower blocks.The inside housing should now swing freely in all directions.If shipment has to be made by you occasionally via carriers, suchas railway, airfreight or forwarding agents, we would recommend in yourown interest to re-mount the shock protection and to ship the unit only inits orig

4、inal packing.The shock protection and the packing is not necessary for transportationby car, truck or Broadcasting Van, provided the unit is handled with careduring such transportation and when loading and unloading the equipment.8. July 1977 Vo/sh/ge1RadioFans.CN 收音机爱 好者资料库You have acquired a preci

5、sion instrument whenyou bought the EMT 240 Reverb Foil. It was de-signed for field use and is therefore made towithstand mechanical shock found under normaloperating conditions. Do not subject theunit to excessive accellerations treat it with thesame care with which you would handle a taperecorder,

6、for example. This will assure that theexcellent performance specifications of the EMT240 will be maintained for some time to come.Unpacking instructions andpreliminary set-upYou have just opened the outer packing case please read on before you unpack the unit anyfurther.1. Remove the foam cushions o

7、n top of and onthe left and right of the inner carton. Check tosee that all of the accessories in the plasticcovered boards correspond to the list on page4.2. Carefully lift out the inside carton. Do not laythe unit on its side under any circumstances!3. Open inside carton.4. ATTENTION!The unit cont

8、ains an a d d it io n a I protectionagainst shock, in order to prevent any dam-ages caused by shock or other impacts due torough handling in transit.Before operation please remove the shockprotection in the following sequence:Open one side of the housing take the wrenchof the accessories and loosen

9、nuts at the lowerwooden blocks until the bolts will release theinside housing take off laterally the squeezedupper blocks take off laterally the lowerblocks.The inside housing should now swing freely inall directions.If shipment has to be made by you occasion-ally via carriers, such as railway, airf

10、reight orforwarding agents, we would recommend inyour own interest to re-mount the shock protec-tion and to ship the unit only in its originalpacking.The shock protection and the packing is notnecessary for transportation by car, truck orBroadcasting Van, provided the unit is handledwith care during

11、 such transportation and whenloading and unloading the equipment.5. Locate unit at desired spot and connect electri-cally (page 8). Check proper line voltage set-ting!Turn unit on. Push the reverberation timebutton () for about 10 seconds. The unit isnow ready for operation.6. Save all packing mater

12、ials! Re-ship only in theoriginal packing.TRANSPORT IN UPRIGHT POSITIONONLY!2Technical DescriptionThe Reverb Foil EMT 240 is a device for produc-ing reverberation.The principle involving the use of a flat, tensionedplate for the creation of reverberation, which hasbeen used for the past decades, has

13、 been re-tained in this new device. In the course of techni-cal improvement and the significant reduction insize, the material used in the vibrating plate hasalso been changed: The EMT 240 Reverb Foiluses an electroplated gold foil of great purity (24carat “coin gold”) with a thickness of only 18j.j

14、m(.00071”) and 270 x290 mm (10.6”xl 1.4”) size.This foil is mounted in a frame under tension,excited by a driver, and sensed by a pick-upsystem.Changing the Reverberation TimeThe reverberation time is changed as before bybringing a damping device in close proximity tothe foil. A vibrating foil such

15、as this gives offenergy to the surrounding air (sound field); bybringing an absorber more or less close to thissound field, energy is removed and the decay isdamped to a greater or lesser extent.This method not only has the advantage of damp-ing all frequencies equally and without erraticbehavior (a

16、s may occur due to the complex inputimpedance of a mechanical system when damp-ing is done electrically by changing the imped-ance of the transducer), but it is also possible,using suitable means, to make this absorptionfrequency dependent and thereby to compensatethe response of the reverberation t

17、ime. Thesefrequency dependent resistances are producedby openings in the damping plate. The pictureshows slots in the actual damping material whichserve this purpose. By varying the slot widths andthe ratio between slot and damping surface, therequired equalization is obtained.Remote Reverberation T

18、ime ControlThe damping plate may be moved by remotecontrol. A complete description, including connec-tion means, is given on page 9.34567Alignment and CalibrationIMPORTANT! A reverberation time of 2 seconds is to be set for all measurements!applicable from serial no.139 onThe level alignment of the

19、Reverb Foil EMT 240 may be undertaken in various ways, all of which produce thesame result.1.Alignment according to the “Braunbuch” specifications 054 or V 54, only applicable to studio systemsset up according to “IRT BRAUNBUCH” specifications:Feed a test signal of 1 kHz at 0 dBabs from a low impeda

20、nce source oscillator (Ri 50 ohm) to the input. 1.2.Measure at the test jack using a high impedance volt meter or multi-meter (Ri 10 kohm/volt); set INPUTpotentiometer to produce reading of 0.245 V ( -10 dBabs)1.3.Replace the test signal with a 1 kHz third octave white noise signal (e.g. part 1 of t

21、he Reverberation testtape) at a level of 0 dB. Adjust OUTPUT potentiometer so that 0 dB level is measured at the output of the unit.Since the measuring instrument used influences the reading of white noise level, it is recommended that thesame meter be used both for measuring input and output levels

22、.2.Alignment for studio systems using peak level indicators and any peak alignment levels:2.2.2.1.Feed a test signal of 2 kHz at standardline level (e.g. +6 dB) from a lowimpedance source oscillator (50 ohm) to the input.Measure at the test jack using a volt-meter, peak level indicator or highimpeda

23、nce multi meter ( 0 kohm/volt); set the INPUT potentiometer toproduce a reading of 0.49 V( -4 dB).2.3.Replace the test signal with a 1 kHz third-octave white noise signal (e.g. part 1 of the reverberation testtape) at standard line level (measured using studio peak indicator). Adjust OUTPUT potentio

24、meter so thatstandard line level also appears on the peak indicator at the output of the unit.3. Alignment using vu meter:3.1.Feed a test signal of 1 kHz at standard line level (e.g. +4, +6, or +8 dB) reading ZERO on your standardvu meter with proper vu range pad, to the units input.3.2.Measure at t

25、he test jack using a highimpedance volt meter or multi-meter( 210 kohm/volt); set the INPUTpotentiometer to produce a reading of0.245 V -10 dB abs8Replace the test signal with a 1 kHz third-octave white noise signal (e.g. part 1of reverberation test tape) orprogram material at standard line levelmea

26、sured using your standard vumeter) and adjust OUTPUT potentio-meter so that identical levels appearboth at the input and output of eachchannel.To check the transmission characteristics and to facilitate alignment of the Reverb Foil EMT 240 we can supplya test tape (tape speed 15 ips (38.1 cm/s) equa

27、lization IEC/CCIR) which obviates the use of white noise genera-tor and third-octave filter. This test tape has the following program:1. Level alignment partAnnouncement; Third-octave band white noise; mid frequency 1 kHz; peak recording level; duration approxi-mately 2 min.Yellow leader2. Frequency

28、 response partAnnouncement; Third-octave band white noise. 27 mid frequencies from 40 Hz - 12.5 kHz each with announce-ment; (duration each band 20 s) 14 dB under peak recording level.Alignment using sine wave signal is not possible since the reverb foil - as with every echo chamber - produces amult

29、itude of closely spaced self-resonances and therefore would yield a highly frequency dependent outputlevel.The frequency response is also best determined using third-octave white noise, but otherwise measured as usual:The output level as a function of frequency is measured with a constant level (-14

30、 dB) at the reverberation unitinput. The response should lie within the tolerance (low frequency cut-off filter in O dB position).In general it can be stated that minor deviations from the tolerances are not acoustically noticeable.A level recorder permits this measurement to be made using a sweep s

31、ignal. The time constant of the recordermust be large enough so that the level variations for small shifts in frequency are integrated. Further informationregarding sweep frequency measurements may be found in the instructions for such equipment. The drivesection of the Amplifier EMT 262 may have it

32、s low frequencies attenuated with three different time constants.The switch on the front panel of the amplifier is to be operated with a screw driver. The positions “0 dB” to “-24dB” are shown in the response graph. Purpose of the low frequency cut-off: In a room the low frequency rever-beration com

33、ponents always have a longer reverberation time than the high. Often it is desirable, from a produc-tion stand point, to reduce the low frequencies in the spectrum with respect to the high frequencies. In an echochamber this requires structural changes, such as low frequency absorbers. In the EMT Re

34、verberation Foil, thesame effect is achieved with a multi-step, low frequency cut-off filter.910111213Technical DataReverberation timereferred to 500 HzNoise level at Tr = 2 5 Unweighted Signal-to-Noise ratio, rms Weighted Signal-to-Noiseratio, peakMinimum input signal for full drive Peak mea-sured

35、vu measuredInput impedanceMaximum output level at 1 kHz and Tr = 2 5Usual reverberationreturn levelOutput source impedanceMinimum load resistanceRemote controlControl voltage requirement Power requirementa) AC supplyb) DC supplyWeightDimensionsSubject to change.0,7.55 65 dB 60dB0.775V rms (0 dB)appr

36、ox. 0.4 V rms ( 5 dB) 5 kQ balanced and floating+ 21 dBm for 1% THD6.l0dB, relative to direct channel 40 Q balanced and floating200 C)Silicone damped linear motor with control elec-tronics and position indicator.24 VDC I 0.25 Aswitchable 200. 250 V or100. l30V,50/60H25VA24 VDC I 0.8 A67 kg (148 lbs.

37、)640 x300X625 mm(251A” x 12” x 25”)(w x d x h)14151617RL: EMT 240Alignment hints for units beginning with serial No. 195 (with AmplifierEMT 262 beginning with serial No. 23337).Beginning with the above named serial numbers, the drive aznplificrs havebeen coupled v.a pin 5 of the amplifier connector.

38、The heretofore published level indications are still valid, but for calibrationor operation with one amplifier inserted.There are three alignment possibilities:Input:0 dB, f= 1 kHz (third octave white noise)and T = 2 sec, produces at the Output:Test Jack Audio OutputI.1 amplifier plugged into unit-1

39、0 dB0 dBII.2 amplifiers plugged into unit, feed to only one input -.16 dB.3 dBIII.2 amplifiers plugged into unit, both irputs fed from same source-10 dB+3 dBNote: Measure the level at the test jack using high impedance millivoltmeter, R11OO kQ.Drive Amplifier:For a 0 dB nominal line level, the level

40、 control R I (in tile amplifier,ncctssible at the front panel) is to be adjueted so that a level of -13 dBis obtained at test point (C).The R128 potentiometer sets the limiter threshold. After nomiual align-ment: input = output = 0 dB, application of a +8 dB signal to the inputhould result in 0.5 dB

41、 limiting at the output.The R 140 potentiometer determines the total amplificatioi as functionof the trcnsducer sensitivity.4The potentiometer R 140 (in the reverb unit, 22 k at the drive trans-former) is to be adjusted to yield a level of -10 dB at the test jack.Pickup amplifier:The R 2 control (ac

42、cessible at the front panel) determines tiie pick-upamplification. For nominal amplification of approx, 81 dB, the weightednoise level at the output should be -54 dB equivalent to an unweightednoise of approx. -62 dB peakNote: The front panel accessible gain controls are set to thefoLLowin; scale marks for the standard factory alignment:input : 5 - 7output: approx. 7Kippenheim, May 27th, 1975P1/sh18