PA Audio Amplifier

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General Information Operating Instructions Precautions Speaker Connections Catalog

Speaker Connection

General instruction for all type of PA System. Check catalog / dealer in case of doubt.
LOUDSPEAKER CONNECTIONS - Amplifier is like a  generator, just as connecting too high a load can damage the generator, the same way overloading amplifier through wrong connections or mismatch of loudspeakers can damage the amplifier. Amplifier delivers power output to two different output terminals:  (one to be used at a time) Low voltage high current output called 4 ohms, 8 ohms, 16 ohms. This method is also called Direct speaker connection. 70V/100V line which is high voltage & low current output system where the speakers must be fitted with Lets or fed through Line Matching Transformer.
Direct speaker connections- On 4ohms 8ohms 16ohms only Loudspeaker/Driver Units of 16ohms impedance type should be connected and properly matched see next pages for loudspeaker connections. Loudspeaker wiring can be done in series parallel or series-parallel, to achieve correct matching. Thick wires (min.23/36PVC)must be used to avoid excessive  loss of power. Select one impedance only. Never connect some speakers to COM-4ohms and other to COM-8ohms or COM-16ohms as this will damage the amplifier. Calculate the impedance of group of speakers carefully and select correct matching impedance to ensure of loudspeakers and amplifier. In direct connections long loudspeaker wires should not be used as the power will be wasted in long wires. Handing capacity of loudspeakers/ Units should be at least double the power output rating of the amplifier.
70V-100V LET Connections - This system is more suitable for large installation where the speakers have to be installed at long distance from the amplifier. The speakers/unit used must have either an inbuilt Line matching  Taro (Motor separate LET are used. The wattage taping selected on the LET should be 10Watts or maximum 20Watts The total wattage load of the speakers/units connected to the amplifier should not exceed the rated power output of the amplifier. This system fully safeguard the speakers/units from any damage as the power reaching the speakers/driver units cannot exceed the wattage tapping of the LET.

Types of Loudspeakers Used In Public adders System
Driver Units with Reflex Horns - These give high intensity of sound and are most suitable for speech in cut door installations. Larger the diameter of the horn better will be the sound reproduction. For example 21”horn shall give better sound than 18’’horn. Driver Unit give best performance when fed with 10-20W of power. Since the frequency response of the driver units-reflex horns is narrow and limited these are more suitable to speech than for high quality reproduction of music. Larger the diameter of the horn used better will be the reproduction of sound. For instance, a 21" diameter horn will give comparatively better performance than an 18" diameter horn when both are used with a similar driver unit say ARCH AU-35 or AU-40 A driver unit will give its best performance when it is fed with one-third to one-half of its rated power handling capacity. For instance a driver unit like AU-35 will give best performance when it is being fed between 10 to 15 watts from the amplifier. This is because the driver unit has to handle certain peak music sound signals which may be as high as three to four times the power wattage being fed to it by the amplifier.
Sound Columns - These ensure less howling and  feedback. These are suitable for indoor or outdoor use. Good for speech and music. These distribute the sound evenly and equally amongst the entire audience from the front row the back row.  These are ideally suited for indoor installations. Column speakers distribute the sound evenly and equally amongst the entire audience from the front row to the back row. The frequency response of column speakers is much better and wider thus resulting in more natural reproduction of sound. column speakers may also be used in outdoor installations when better quality of music reproduction is desired. The use of column speakers also ensures less howling and feedback as compared to heavy duty box type speakers.
Box Speakers ( Heavy-duty 8" to12" full range single speaker fitted in wooden cabinets) - These provide good quality music at social functions and live musical programmed and are suitable for reproduction of recorded music or in installation for live musical programmed.                                        

Precautions
Speaker Connections : Low Impedance Speaker Impedance taps of 4 ohms, 8 ohms and 16ohms have been provided for direct connection of speakers to the amplifier when the distance between the amplifier and speakers is less than 50 meters. Use 23/36 or thicker cable for connections. Be sure that the total impedance of the speakers is equal to or more than the impedance specified on the terminal strip
Phasing Of Loudspeakers : When two or more speakers/units are installed in the same area and are facing in the same direction. it is essential that their cones/ diaphragms act in unison. Otherwise ,the sound level of one speaker will be canceling the sound level of the other. To avoid any mistake the terminals of all driver units are marked L1 and L2. (For correct wiring refer to the sketches of loud-speaker connections.

Loudspeaker Connections : The loudspeaker connections must be made to only one selected impedance i.e. either to "COM" and 4 ohms or to "COM" and 8ohms "COM" and 16ohms terminals on the amplifier. When speakers are connected to any one of the above impedances, make sure that no speaker is connected to either 70 V or 100V line output terminals. Making connections to two impedance tape simultaneously will cause overloading and damage to the amplifier.
Selection Of Loudspeakers : Proper selection of column speakers/driver units-horns and their appropriate impedance matching to the amplifier, avoiding over loading and short circuit while making connections are of utmost importance in speaker installations. Any mistake made would not only result in inferior sound quality but would also become a cause for damage to the amplifier.

LOUDSPEAKER CONNECTIONS
Connecting Two Speakers : Connecting two or less loudspeakers to a powerful amplifier like CPAy760 is not is not recommended. However in extreme necessity. two speaker may be connected only as illustrated and explained below:   Total Impedance=16ohms +16ohms=32ohms  Since each speaker is be fed with 10 to15 watts (in any case, not more than 20watts) power from the amplifier, the power requirements of two speakers would be less than 40 watts. Connecting two speakers/units in series with resultant impedance of 32 ohms between COM and 8 ohms tap on the amplifier will result in a condition of Under loading ensuring that AR-40 deliver less than 40 watts. Connecting two loudspeakers to a powerful amplifier is not recommended. However, in extreme necessity, two speakers may be connected. Speakers can be connected in series between "COM" & 8ohms. In this under loading condition amplifier will not deliver more power output and amplifier should be operated at low volume. 

Connecting Four Speakers : Four speakers are first wired in two series groups of two speakers each and then the two groups are connected in parallel. The power requirement of driving four speakers would be about 60 watts (in any case, not more than 80 watts). Therefore four speakers should be connected in series /parallel. Four speakers are first wired in two series groups of two speakers each and then are connected in parallel. Impedance of two speakers/units of 16ohms each connected in series (16x2)=32ohms. Two such groups are when connected in parallel the resultant impedance will become 32ohms divided by the number of groups(32ohms/2)=16ohms The power requirement for driving four speakers would be about 100watts (in any case not more than 120watts). Therefore, four speakers should be connected in series/parallel. In this arrangement, the resultant impedance works out to be 16ohms but connecting the speakers between "COM" and 8ohms will again create a condition of 'Under loading' ensuring that the amplifier can only deliver about 100watts power output.

Connecting Six Speakers : Impedance of two speakers/units of 16ohms each connected in series (16x2)=32ohms. Two such groups are when connected in parallel the resultant impedance will become 32ohms divided by the number of groups(32ohms/3)=10.66ohms These should be connected between COM & 8ohms tap. This is also a case of "UNDER LOADING."
Connecting Eight Speakers : The above illustration shows how eight speakers are connected in series/parallel arrangements. The resultant impedance works out to be 8ohms so these are connected between "COM" & 8ohms tap. Which is a case of "Equal Matching" as eight speakers can safely handle the power output of this amplifier.

70V-100V LINE Connections

This system is more suitable for large installation where the speakers have to be installed at long distance from the amplifier.  The speakers/unit used must have either an inbuilt Line Matching Trio. (LET) or separate LET are used. The wattage taping selected on the LET should be 10Watts or maximum 20 Watts. The total wattage load of the speakers/units connected to the amplifier should not exceed the rated power output of the amplifier. This system fully safeguard the speakers/driver units cannot exceed the wattage tapping of the LET. 

70V/100V Line System : 100volt line system is a standard system for connecting speakers in complex and large installations For using the above system, one should preferably select speakers/unit-horn with built-in line match transformers each marked with selectable wattages like 5W,10W,15W and20W. However, separate line matching transformers like ARCH LMT can also be mounted on the loudspeakers for 100V line operation.  Although 100V line system is basically meant for installations requiring large number of speakers yet nothing prevents one from using this system when only two or four loudspeakers are to be installed. 100V line system offers many distinct advantages over the 4-8 ohms direct connections. In large PA installations, it permit the distribution of power output of amplifier to different speakers at different output wattages. For instance the loudspeakers close to the stage ( micro-phones) need less power to avoid feedback, while those placed at a distance have to be fed with more power output. Similarly, areas where more noise is anticipated from the audience still more power can be fed to the speakers by connecting these to higher wattage taps on the line matching transformers. 100V line system simplifies the wiring of the speakers as no calculations are required to arrive at the correct matching impedance.  The loudspeakers can be wired in parallel with two wires running from one end to the speakers placed at the farthest distance.   The system protects the life of the driver units as these will work with in the selected wattages to which these have been connected to, even when the volume on the amplifier is turned to 'full'  The loss (wastage) of power output in the cables/wire is negligible. If the loudspeakers is wired 50 mats. (160ft) away from the amplifier and is fed with 15 watts power output from it, 14 watts will reach the driver unit as against 10 watts that would have reached on 4ohms-8ohms operation. Even when the speakers are installed at 200 metres (650ft) distance the loss (wastage) of power in the cables will be nominal. These two illustrations depict use of 100V line operation. The four loudspeaker nearer the stage are fed with lesser power level. Both the rows of speakers are fed from the same amplifier. Please make sure that the sum total of the wattages selected on each speakers does not exceed the Rated output power of the amplifier, For instance, if a total of 10 speakers are connected to SSA-250, 6 on 10watts tap and 8 on 20 watts tap the total power output that these speakers will draw will be 6x16watts=60watts plus 8x20watts=160watts i.e. 220 watts, which does not exceed the Rated power output of SSA-250 and thus the amplifier is safe. Similarly it can be worked out for SSA-180. Caution: when 100volt line is being used, no speaker should be connected to 4ohms 8ohms (low impedance) tap. Use of 70VLine  When a loudspeaker /unit with line matching transformer is wired to its 15 watts tap and connected between COM and100V tap, it draws up to 15watts power from the amplifier, if the same is connected between "COM" and 70V, it will be able to drew only half the power output i.e. up to 7.5 watts . A good use of 70V line tap can be made in installations where large number of speakers/units are to be installed for more even distribution of sound.

Loudspeaker Cable Size & connections

100Vline :When installing a 100Vline system, it is important that the correct size of cable is used to connect the speakers to the amplifier. The following chart gives an indication of cable (number and diameter of wires in mm).

100V Amp 24/0.2 32/0.2 48/0.2 80/0.2 128/0.2 122/0.25
30W 800m 1066m 1600m 2666m 4266m 6400m
60 400m 533m 800m 1333m 2133m 3200m
120 200m 266m 400m 666m 1066m 1600m
240 100m 133m 200m 333m 533m 800m
As the voltage on the line can approach 100volts, installation must follow best practice with double insulated cable being used. cable runs should be kept away from any potential source of interference such as 3phase mains, data, telecom cables etc. 100Vline system must always be wired in parallel.

Low Impedance : All the amplifiers in the Etra range have the facility for connection of low impedance loudspeakers. On low impedance, to minimize power losses, short cable runs are recommended. Where it is intended to use multiple low impedance speakers to cover an area, the speakers must be wired in a series/parallel arrangement in such a way to present the correct load to the amplifier. 

Note : The total load presented to the amplifier must not exceed the rated output of the amplifier or damage can result. The total load impedance presented to the amplifier must never be below the rated amplifier impedance, otherwise damage can result. To avoid damage to the speakers the total wattage of the driver units should be at least 30% higher than the rated power output of the amplifier.

You must never mix 100V line and low impedance speakers on the same system.

|| Amplifiers - Booster / Power / Two Zone / Instrument || Audio Mixer - Echo / Stereo || Conference Systems ||

 || Cassette - Player / Recorders / Preamplifiers || Driver Units || Horns - Reflex / Speaker || Microphones || Mobile PA || 

|| Speakers - Ceiling / Column / System / Wall / Professional || Sound System || Stand - Floor / Table / Accessories ||

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Due to continuous design & technical development specifications are subject to change without notice.