VTX Manual
Contents
1. USER GUIDE oO 10 PCB Location of Jumpers J1 J2 and J3 HEATSINK is TRI Sui ZON Sz S p Top gga 40 m FAST SLOW 5 cin TEK gt A a o UE tete at ie BEAR PANEL ui n wo DE MC A 0 EP et che CONNECTORS Fag R c26 N oe i 5D ES En mm pe J1 selects fast slow for channel A J3 selects fast slow for channel B The slow release setting is the preferred setting for most full range program music applications and is the factory default setting In situations where there is a music signal present but limiting is caused by a loud additional vocal e g D J the slow setting will not allow the music level to recover quickly enough after the vocal signal has stopped producing an effect similar to an auto voice over circuit with the release set too slow This can be overcome to some extent by using the DCP s fast setting In systems with an active crossover the DCP should be set to slow for channels operating at bass frequencies and fast for channels operating at mid or high frequencies Both channel A and channel B DCP circuits can be disabled by means of a single internal jumper J2 also located on the upper main PCB see fig 1 External visual indication of DCP enabled disabled is provided by means of an LED adjacent to the channel A Input socket Disabling DCP is not recommended as this will not allow the amplifier to produce any more power without clipping nor will it give any improvement in th2. D USER GUIDE NOTE If the PEAK LED s are on no damage is being caused to the amplifier it merely indicates waveform clipping or clip protection if the DCP is enabled Bridge The Yellow BRIDGE LED illuminates when the amplifier is switched into the Bridge mode Power The Green POWER LED indicates that the amplifier is connected to the mains supply and switched on 11 Specifications GENERAL SPECIFICATION Po Xr TX1200 __VTX1500 XLR XLR XLR OUTPUT CONNECTORS 1 Speakon amp 2 heavy 1 Speakon amp 2 heavy 1 Speakon amp 2 heavy duty binding posts per duty binding posts per duty binding posts per channel channel channel PROTECTION VI Limiting VI Limiting VI Limiting DC offset DC offset DC offset Thermal shutdown Thermal shutdown Thermal shutdown Inrush current limited Inrush current limited Inrush current limited LED INDICATORS Peak Output Peak Output Peak Output Signal present Signal present Signal present Protection Operating Protection Operating Protection Operating DCP on DCP on DCP on low noise fan fan high speed fan eee 483mm x 370mm x 483mm x 370mm x 483mm x 370mm x 132mm 132mm 132mm WEIGHT 14 50kg 15 55kg 16 00kg TECHNICAL SPECIFICATION Een VTX750 VTX1200 channel channel channel RATED OUTPUT POWER 40 265 Watts RMS per 425 Watts RMS per 525 Watts RMS per ee RATED OUTPUT POWER 80 190 Watts RMS per 270 Watt
3. VTX Amplifiers Installation amp User Guide vo Cloud Electronics Limited 140 Staniforth Road Sheffield S9 3HF England Tel 44 0 114 244 7051 Fax 44 0 114 242 5462 E mail info cloud co uk Web site http www cloud co uk VTX Amplifiers INSTALLATION AND USER GUIDE _ N oN A oO Safety Notes e Do not expose the unit to water or moisture Do not expose the unit to naked flames Do not block or restrict any air vent Do not operate the unit in ambient temperatures above 35 C Do not touch any part or terminal carrying the hazardous live symbol while power is supplied to the unit e Do not perform any internal adjustments unless you are qualified to do so and fully understand the hazards associated with mains operated equipment e The unit has no user serviceable parts Refer any servicing to qualified service personnel e If the moulded plug is cut off the lead for any reason the discarded plug is a potential hazard and should be disposed of in a responsible manner For more detailed information refer to the rear of the manual General The VTX amplifiers are a range of rugged high quality professional power amplifiers designed to give long reliable service when continuously operated at high power levels All models feature very low distortion and noise together with a high slew rate A comprehensive range of protection circuits including Cloud s DCP Dynamic Clip Protection allows the
4. amplifier from short circuit or other adverse loads Standard fixed level limiters often fitted to power amplifiers suffer from the problem that they assume the amplifier is driving the lowest rated load at a continuous level Consequently the limiter will not allow the amplifier to deliver its maximum power into higher impedance loads nor deliver it s maximum transient power Cloud s DCP circuitry gets round this by detecting when the amplifier distortion reaches 0 5 and reduces the amplifier gain as needed to keep the distortion at that level thus preventing noticeable clipping In addition to clip limiting DCP also reduces the gain when the amplifier goes into VI limiting further reducing stress on the output components when the amplifier is driven into a short circuit or low impedance load VCA chips have not been used in this design hence avoiding the noise distortion and slew rate limit that can be associated with them In fact when the DCP is not limiting its gain control circuit has no effect on the slew rate and makes no measurable contribution to the amplifier noise or distortion The DCP has an attack time of 5mS which ensures accurate control of gain whilst not reducing gain excessively because of transients Each channel has a separate internal jumper to select either a fast or a slow release time These jumpers are both located on the upper main PCB see diagram on following page 12 08 02 V3 VTX Amplifiers INSTALLATION AND
5. amplifiers to tolerate a good deal of abuse and help prevent damage to speakers Installation These amplifiers occupy three units i e 5 25 133mm of standard 19 rack space and are 330mm deep though 410mm should be allowed to clear the connectors All three amplifiers are force cooled with cool air drawn in from the front and exhaust from the rear which enables any number of amplifiers to be racked without the need for special ventilation provided that a free flow of air is available at the rear of the rack housing Input Connections The inputs to the amplifier are electronically balanced and use XLR type connectors The inputs are wired to the standard convention of pin 1 Ov pin 2 in phase ve or hot pin 3 reverse phase ve or cold the shell of the XLR is connected to the chassis ground If the unit is operating in a location which has a high level of electrical or magnetic disturbance or is close to a TV or radio transmitter we suggest that the input cable screen be connected to the shell of a metal type XLR connector If the signal is from an unbalanced source connect pin 3 to pin 1 Ov inside the XLR connector and use pin 2 as hot Input impedance is 10k ohms balanced 5k ohms unbalanced The input sensitivity is OdBu 775mV for both balanced and unbalanced modes provided that the input is wired as above Each channel also has a link socket this XLR connector is internally wired in parallel with the input XLR and is p
6. e performance of the amplifier To prevent high switch on currents that can blow mains fuses or trip MCBs all models are fitted with inrush current limited power supplies This provides similar protection to a soft start but without the unreliability that can often come with them Level Control Independent front panel level controls are provided for channels A amp B These would normally operate in the fully clockwise position The DCP operates in the post level control circuitry and is not affected by the position of the level control Note that these level controls simply reduce the amplifiers gain they do not limit the power available at the output of the amplifier except when turned fully anti clockwise they simply change the input level required to obtain full power LED Indicators Protect The Red PROTECT LED indicates the operation of various protection circuits built into the VTX range of amplifiers It also illuminates when the 5 Second switch on delay is operating Signal The Green SIGNAL LED illuminates to indicate normal operation of the amplifier and the presence of an output signal above 16dBu 5Vrms Peak The Red PEAK LED illuminates when the amplifiers distortion has reached or exceeds 0 5 THD If DCP is enabled this LED also indicates that the distortion has been detected and the amplifiers gain is being reduced to limit the distortion to this level 12 08 02 V3 EN VTX Amplifiers INSTALLATION AN
7. nput circuits disabled The load should be connected between the two Hot output terminals Speakon 1 2 pins or Red binding posts The Bridge LED on the front panel illuminates when the mode switch is in this position The hot or in phase signal is present on the red binding post of channel A pin 1 of chA speakon and chB speakon Important In the bridge mode the full output of the combined channels is available at the output terminals and care must be taken to ensure that the loudspeakers are capable of handling the available power Mains Connections The amplifier is provided with a 3 pin male Euro connector mounted on the rear panel A suitable mains lead with a female Euro connector and a mains plug is supplied If the plug is cut off the lead for any reason please remember that the discarded plug is a potential hazard and should be disposed of in a responsible manner CAUTION THIS AMPLIFIER MUST BE EARTHED All the VTX amplifiers can be supplied to operate on 220v or 240v A C mains supplies Refer to the service manual if the supply voltage requires changing Protection and DCP The VTX amplifiers all contain protection circuits that disconnect the load if the amplifier overheats because of restricted airflow for example or if any DC is detected at the output A 5 Second switch on delay operates when the unit is switched on to avoid any switch on thumps The amplifiers also contain VI limiting circuitry that protects the
8. rovided to facilitate the linking also known as daisy chain connection of amplifier inputs Output Connections Connection to the outputs of a VTX amplifier can be made by a 4 pole speakon connector or via binding posts The minimum recommended load for all models is 2 ohms per channel in stereo mode and 4 ohms in bridge mode Always terminate output cables at either the binding posts or the speakon Do not be tempted to connect the speakers ve terminal to anywhere else Never connect other apparatus or earth ground references to these output terminals for example do not use the OV connections as a ground reference Because of the high output currents which these amplifiers can produce damage to equipment can result if the above precautions are not adhered to Mode of Operation All amplifiers have a 2 position mode switch on the rear panel adjacent to the Channel B input socket Information on how the position of this switch affects the operation of the amplifier can be found on the following page 12 08 02 V3 N VTX Amplifiers INSTALLATION AND USER GUIDE fo Stereo In the out position marked Stereo the amplifier operates as two independent channels for typical stereo operation Bridge With the switch in the Bridge position the amplifier operates as a single channel unit with a minimum load impedance of 40 all models Channel A input socket DCP and level control are operative with channel B i
9. s RMS per 320 Watts RMS per RR RER FREQUENCY RESPONSE 0 1dB 10Hz to 0 1dB 10Hz to 0 1dB 10Hz to 0 03 Typical 1kHz 0 03 Typical 1kHz 0 03 Typical 1kHz 80 load 80 load 80 load INPUT SENSITIVITY OdBu 775mV RMS OdBu 775mV RMS OdBu 775mV RMS INPUT IMPEDANCE 10kQ Balanced 10kQ Balanced 10kQ Balanced 5kQ Unbalanced 5kQ Unbalanced 5kQ Unbalanced output output output 3us 10 to 90 of 3us 10 to 90 of 3us 10 to 90 of 1V 1kHz 1V 1kHz 1V 1kHz Infinite Mains Fuse ratings Supply Voltage 15vac TA 12 08 02 V3 VTX Amplifiers INSTALLATION AND USER GUIDE oa This product conforms to the following European EMC Standards BS EN 55103 1 1997 C BS EN 55103 2 1997 This product has been tested for use in commercial and light industrial environments If the equipment is used in controlled EMC environments the urban outdoors heavy industrial environments or close to railways transmitters overhead power lines etc the performance of the unit may be degraded The product conforms to the following European electrical safety standard BS EN 60065 1998 Safety Considerations and Information The unit must be earthed Ensure that the mains power supply provides an effective earth connection using a three wire termination When the mains switch is in the off O position the live and neutral conductors of the mains transformer are disconnected however some parts of the produc
10. t will still remain connected to the live and neutral mains conductors CAUTION Installation Do not expose the unit to water or moisture Do not expose the unit to naked flames Do not block or restrict any air vent Do not operate the unit in ambient temperatures above 35 C CAUTION Hazardous Live Do not touch any part or terminal carrying the hazardous live symbol 4 while power is supplied to the unit as it can result in electric shock Terminals to which the hazardous live symbol refers require installation by qualified personnel CAUTION Mains Fuse Replace the mains fuse only with the same type and rating as marked on the rear panel The fuse body size is 20mm x 5mm CAUTION Servicing The unit contains no user serviceable parts Refer servicing to qualified service personnel Do not perform servicing unless you are qualified to do so Disconnect the power cable from the unit before removing the top and do not make any internal adjustments with the unit switched on Only reassemble the unit using bolts screws identical to the original parts In the interest of continuing improvements Cloud Electronics Limited reserves the right to alter specifications without prior notice Cloud Electronics Limited 140 Staniforth Road Sheffield S9 3HF England Telephone 44 0 114 244 7051 Fax 44 0 114 242 5462 E mail Info cloud co uk 12 08 02 V3
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