This amplifier can be operated on 220-240V AC mains supply or 24V-28V Car Battery.

Whenever or wherever main voltage is low, output of the amplifier will be low, as such for voltage correction, use voltage stabilizer.

To protect the set from abnormal electrical conditions, an AC fuse with 3A rating has been provided at the backside. If blown, replace it with fuse of 3A rating.

Double Battery Terminal Strip:- Two battery terminal strips have been fixed on the back plate. Top strip is to connect 24V-28V Car battery. Normally other equipment like ECHO Model ECM-4 (which also operate on 24V DC) is connected alongwith these heavy wattage sets. This additional terminal can be used to provide Car Battery supply to ECM-4. Connect battery wire supplied with ECM-4 to this terminal inone wireTerminal of such units.

It has six microphone inputs. All six are LO-Z or low impedance (200-600 ohms) microphone stages. The big advantage of these LO-Z stages is that it allows you to extend the length of mike wire upto 30 meters. MIC-1 to 5 are equipped with individual slide switches with ‘OFF/LO-CUT/FLAT’ indication & LED indicator. If any mike is ‘ON’, then LED will glow. This gives special convenience to user to control all mikes.  LO-CUT filters permit minimizing of howling and feedback.

MIC-6 stage is selectable with AUX.-1 & AUX.-2. through slide switch. AUX.1 & 2 inputs are to be used to amplify sound of Record Player, TV, Radio, or any Musical Instrument.

Simultaneous inputs can be joined to all inputs. All MIKE and AUX. inputs are mixable. 

BASS CONTROL - This is active Bass Control, which permits cutting and boosting of low frequencies (or thick sounds). At ‘0’ (FLAT) position the amplifier’s response will be normal.

Turning to left (0 to –10) will cut low frequencies. This will protect life of Driver Units, as they cannot reproduce low-freq. This position also reduces & eliminates feedback and howling. Keep between 0 to –5 while using units.

Turning to right (0 to +10)) will BOOST low frequencies. This position gives excellent reproduction of Tabla, Bongo etc. Only box speaker columns should be used in this position.

SPEAKER–DRIVER UNIT SLIDE SWITCH - When using Box speakers keep this switch at ‘SPEAKER’ side. But while using Driver Units, it is compulsory to keep it at ‘DRIVER UNITS’, as it cuts Bass effect and saves units from being damaged.

TREBLE CONTROL: - This control regulates cutting and boosting of high frequencies (shrill / thin sounds). At ‘0’ position, the response is ‘FLAT’ or normal. Turning to left (0 to –10) will cut high frequencies to avoid shrillness. Turning to right (0 to +10) will enhance tonal quality of string instruments and thinner human voices.

MASTER CONTROL: - This acts as a Gate for overall opening and adjusting of combined or mixed volume /output of all inputs. For best results keep this control at ‘6’ to ‘8’ position.

1.  GROUNDING: - For safety and humfree operation, the chesis of the set must be grounded. Join one wire from the ‘Earth’ terminal at the back plate to earth of AC outlet, or water pipe etc.  If more equipment like booster amplifier, cassette player are associated with this amplifier, make sure that their chesis are electrically connected with each other.

2.  SIMULTANEOUS AC/DC CONNECTIONS TO ENSURE UNINTERRUPTED SERVICE: - The amplifier can be connected to AC supply and 24V Car battery simultaneously.  In such case the set will draw power from AC mains. The battery power will act as a ‘stand-by’. In case of electric failure or AC voltage dropping down abnormally, the amplifier will start drawing power from the battery to keep the operation uninterrupted. The amplifier will start operating on AC as soon as AC supply is restored. On AC operation, no battery is consumed. If any supply AC or Battery is available, the Power ‘LED’ on front plate will glow.

3.  MICROPHONES: - Use LO-Z microphones on all five mike stages. All ROXY microphones are LO-Z and match perfectly with this amplifier. Do not use High impedance or HI-Z mikes, as they will produce choking sound. Never blow in microphones. This common practice damages their sensitivity. Speak 1 / 2 / 3 instead while testing. While speaking keep the distance between mike and mouth to app. 10-15 cms.

4.  AC MAINS SUPPLY VOLTAGE IS FATAL, as such do not remove top cover of amplifier, when connected to mains. Also car battery must also be removed or should not be connected, when opening cover.

5.  DC FUSE: - For safety, the amplifier is provided with fuse in DC line. This fuse of 15A rating is position on the backplate. If blown, replace it with another fuse of 10A.

PRE-AMP.OUTPUT: - An output signal of 250mV strength is available through this socket. Setting of ‘BASS” & ‘TREBLE’ control will not effect this output

This can be used firstly for connecting a Cassette Recorder for recording the running programme. Connect to Aux. of any tape recorder. Secondly, for connecting another amplifier for combined higher output. For example, after connecting driver unit/speakers on this set, there is a need for additional unit/speakers, take another amplifier (say RSB-300E). Connect one wire from Pre-Amp. Output of RSB-160E and join to Aux-2 of RSB-300E. Now you can put additional driver units / speakers on this RSB-300E. Keep Master Control of 300W to full and Aux-2 level to choice.

LINE OUTPUT: - An output signal of 1V strength is available from this socket. Connect to any BOOSTER amplifier as above.

DIRECT SPEAKER CONNECTIONS: - COM 4W 8W 16W have been provided for direct connection of units / speaker to the amplifier. These taps are recommended to be used if the distance between the amplifier and speakers is short enough. Use 23/36 or thicker wire for connections.

COM-70V-100V LINE: - This line has been provided for installation when speakers are at a distance from the amplifier and are fitted with 100V Line Matching Transformers. (Read instructions of “Selection of speaker & their Connections”) attached.

HORT CIRCUIT PROTECTION:- The amplifier has a built-in overload protection circuit to protect the amplifier from short circuit in speaker cables, overloading and consequent damage.

When a short circuit or overload occurs due to mis-match or wrong connections in speaker output terminals. The overload protection circuit will start functioning (indicated by choking sound in speakers or driver units connected). As soon as the over-load or short circuit is removed, the normal working of amplifier is restored.

IMPORTANT: - From our past experience of 45 years, it has been observed that poor sound quality in Public Address installations & a good majority of defects in amplifiers are due to WRONG SPEAKER CONNECTIONS. It is therefore very important to understand & avoid mistakes in speaker connections. (Study ‘Selection of speakers ..’ sheet attached).

WARNING: - When a set of speakers are to be connected to the amplifier, if on Direct tapping, one COM terminal is to be used everytime. But it is important to use ONLY ONE TERMINAL OUT OF 4W, 8W OR 16 W.  Similarly on voltage tapping, connect one to COM and other to either 70V or 100V.   NEVER USE TWO TAPINGS AT A TIME.

5 LED ARRAY OUTPUT INDICATOR: - This indicates the output level being delivered by amplifier. When last or 5th LED glows continuously, it shows amplifier is giving maximum output. The volume of the Master should be reduced immediately until the 5th LED start flickering instead of glowing continuously.

As stated above SELECTION OF SPEAKERS AND THEIR CONNECTIONS TO THE AMPLIFIER is the key to the successful use / operation of the whole Public Address Installation. For guidance, please refer to a separate sheet ‘SELECTION OF SPEAKERS AND THEIR CONNECTIONS’ attached.  Some basic points are briefed as under:-

1.  The output wires coming from Output Speaker Tapings of the amplifier should not short. This is fatal, as firstly it will stop the sound output from the speakers. Secondly, it will seriously damage the amplifier. Its AC fuse or inside DC fuse will be blown off immediately, needing a replacement. As such, please ensure that output wires do not short at

a)  Output terminal strip.     
b)  In the connection wires
c)  At driver unit / speaker end.

2.  Wires used to connect driver units/ speakers on DIRECT SPEAKER tapings should be thick (app. 23x36 size). However, while using 70V-100V line tapping thinner wires can be used.

3.  When a number of speaker / units are to be connected, connect them suitably to make a nett impedance i.e. the nett output of all such speaker / units should be just two wires. One of these has to go to COM terminal & other to 4,8 or 16W. Or alternatively one to COM and other to 70V  or 100V line. The same is explained with examples in ‘Selection of speaker and their connections’ sheet attached.

4.  For safety of speakers/units, the total nett power handling capacity must be more than that of amplifier.

5.  Connect all speaker/units at the Output FIRST and only after that connect the AC lead to the AC supply outlet or Battery terminal at backplate to Car battery terminals.