VTL MB-125, Owner'S Manual

Page 1: ...VTL MB 125 Monoblock Power Amplifier Owner sManual ...

Page 2: ...produced or transmitted in any form or by any means electronic or mechanical for any purpose without the express written permission by VTL Version History Version 2 2 April 23 2008 Copyright 2009 by VTL Amplifiers Inc All rights reserved 4774 Murrieta Street Suite 10 Chino CA 91710 USA Phone 909 627 5944 Fax 909 627 6988 http www vtl com e mail mail vtl com Part Number OM 0010 201 ...

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Page 4: ... 3 The MB 125 Front Panel 4 Check for tube placement 4 MB 125 Back Panel 5 The MB 125 Back View 5 Connecting Your Amplifier to your system 5 Voltage Setting 6 Power Source for your Amplifier 6 CHAPTER 3 7 OPERATING THE AMPLIFIER 7 Powering your system on 7 Ground Loop Hum 8 Powering the system off 8 Tetrode Triode Switching 8 Bias Checking and Setting 8 Top view and Bias Measurement points of the ...

Page 5: ...ower on Period 12 Tube Types 12 Tube Life 12 Changing Tubes 13 Changing the AC and B Fuses 14 Cleaning 14 Transporting MB 125 14 CHAPTER 5 15 SPECIFICATIONS 15 CHAPTER 6 16 WARRANTY 16 APPENDIX 17 Warranty Registration 17 Service Notes 17 MB 125 Owner s Manual VTL ii ...

Page 6: ...owards your enjoyment of music and give you many hours of listening pleasure Symbol Conventions used in this guide Certain symbols are used in this owner s manual to draw your attention to important points being discussed For your own safety and that of your equipment you should note and heed the warnings that follow these symbols The Warning Pay particular Attention symbol used is and the Warning...

Page 7: ... are operating Turn off the amplifier and allow the tubes to cool down before attempting to work with the tubes Do not attempt to disassemble the amplifier chassis or remove any covers from the amplifier Always consult with your VTL authorized dealer or the VTL factory support department before attempting any service work on any VTL unit Always connect your loudspeaker to the amplifier before powe...

Page 8: ...sure that none of the flaps is trapped under the carton lift the carton off the unit 3 Lift the top foam away from the upside down unit and carefully cut away the plastic from around the amplifier 4 Lift the amplifier up and away from the packaging either by holding onto the metal handles on the front of the unit or by rolling the unit onto a short side and then again so that it lands on its four ...

Page 9: ...on the top deck of the amplifier The cage is mounted with three screws on each side of the amplifier Loosen the screws and lift the wire cage slowly and carefully Do not let the cage touch or hit any of the tubes inside the amplifier Keep the cage and the screws in a separate place while you re working on the amplifier 2 Make sure that the amplifier is not connected to the power outlet and not tur...

Page 10: ... CD Tuner Tape DAT Turntable etc to the preamplifier Follow the instructions on your preamplifier and source component manuals to connect these components together 2 Connect the power amplifier to the output channel of the preamplifier The interconnect cable between the amplifier and the preamplifier links the input channel of the power amplifier to the output channel of the preamplifier The monob...

Page 11: ...r country where you made your purchase The voltage setting should be marked on the Serial Number Badge located on the back panel of your amplifier Check to make sure that this complies with your local voltage rating before plugging in and turning on your amplifier Your amplifier is shipped with a power cord that matches the requirements of your country If you need a replacement and you are not sur...

Page 12: ... or blow a fuse The power on switch is located on the right hand corner of the amplifier s front panel When the unit is powered off the switch points in the 0 position Clicking the switch once turns on the unit and the switch is in the 1 There is a green power on LED to the left of the front panel The LED light should be on when the system is properly powered on 1 Repeat the above step for the oth...

Page 13: ...a choice of listening to your system in tetrode mode or in triode mode In tetrode mode your amplifier is capable of delivering up to 125 watts per channel This mode of operation is most suited to music that requires a wide dynamic response and lots of bass punch Triode mode for the MB 125 operating at approximately 60 watts per channel is most suited for vocal and small instrumental ensembles In t...

Page 14: ... such a meter you can purchase one at a local electronics supply store such as Radio Shack The Radio Shack catalog numbers for usable multimeters are 22 166 22 167 22 163 22 174 or even 22 179 Use the following procedures to measure and adjust the bias setting 1 Make sure that the amplifier is powered off Remove the protective metal cage of the amplifier and make sure that there is sufficient room...

Page 15: ...the following procedures 1 Keep the positive probe from the millimeter in the same measurement point where you found the out of range bias reading Locate the bias adjustment point whose number corresponds to the bias measurement point See Figure 2 for the locations of the measurement points 2 Insert a 1 8 flat tipped screwdriver with a plastic shaft or a properly insulated handle into the bias adj...

Page 16: ...Top view and Bias Measurement points of the MB 125 Amplifier MB 125 Owner s Manual VTL 11 ...

Page 17: ...2AT7 tubes for the input and driver stages Tube Life Your VTL amplifier has been designed to ensure long tube life Tube replacement need not be considered until after approximately 3000 hours of use roughly 3 to 4 years depending on your listening requirements As the tubes age beyond their peak performance they begin to lose their ability to provide full power This usually results in some loss of ...

Page 18: ...fier stay power off for at least 15 minutes before you start working with it Make sure the tubes are cool before you touch them Using a Philips 2 point screw driver remove the protective cage from the unit by loosening the two screws from the side of the amplifier Carefully remove the cover and the screws and store them in a safe place 3 Removing Tubes Locate the tube you need to remove and hold o...

Page 19: ...e cap Take the fuse out and replace it with a new one and insert the fuse cap back into the holder pushing it downward while turning it in the clockwise direction to lock it in place WARNING For continued protection against fire hazard only replace the fuse with the same type and rating as was originally specified for the amplifier If you have problems locating the correct fuse contact your VTL de...

Page 20: ...vity 125 W 700mV Input Impedance 145 000 Ohms Optimum Load Range 2 8 ohms S N Ratio 125W tetrode S N Ratio 60W triode 95dB 120 Hz 95dB 120 Hz Power Consumption Idle 100 W Full Power 300 W Primary Mains Fuse Rating 100 120V 6A Ceramic Slo Blo 220 240V 3A Ceramic Slo Blo B Fuse Rating 0 75A fast acting ceramic Dimensions W 16 inches 40cm D 12 inches 30cm H 7 inches 18 cm Weight 42 lbs 22Kg per monob...

Page 21: ...ct recording of the serial number of the preamplifier on your warranty registration card and mailing it with your purchase receipt to VTL If a VTL product fails to perform properly under the above warranty then the purchaser s sole remedy shall be to return the product to the authorized VTL dealer or to VTL Amplifiers Inc where the defect will be repaired without charge for parts and labor The pro...

Page 22: ...rieta Street Suite 10 Chino CA 91710 USA To help you keep a record of the serial number and purchase information please enter the following information into this manual Product Model Number ___________________________ Serial Number ___________________________ Purchase Date ___________________________ Authorized Dealer ___________________________ Service Notes Date Service Initials ___________ ____...