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MB 845i Valve Insertion
Page 1: ...dealer or one of our team Valve amplifiers do need a little more attention than their solid state counterparts but the sonic results are well worth it In this manual we have tried to include everything that you need to know Please let us know if you find any errors or feel that we have missed anything out The MB 845i are push pull all triode power amplifiers using the fabulous 845 high power triod...
Page 2: ...ode N A Run min 6 hour test Check input Output Valve Bias level v Sound Quality Channel Balance Valve Microphony Valve Seating Hum level L R mv RF Test LED brightness Serial No sticker and recorded Mains voltage 110 120 230 240V IEC Mains Fuse 5A Soft Start Fitted N A Sales invoice Bottom label Credit card receipt Customer survey form Bias meter Transformer Protection N A Upgrades Output valves 1s...
Page 3: ...Page 3 MB 845i Valve Insertion ...
Page 4: ...to Earth terminal 6 SWITCH ON The blue mains indicator should light up The 845s will glow bright yellow You will likely hear a humming noise for about 20 secs through your speakers this is normal After about 40 seconds the amplifier should now be working The small valves should have a visible orange glow from the cathode heaters With the pre amp volume control set to minimum there should be no sou...
Page 5: ...the system up and play some music with plenty of bass e g dance music preferably in mono FM tuners are usually switchable to mono and stand the speakers close together If correct you should hear plenty of bass if not reverse the terminals for one channel only either at the amp or speaker You will now hear more or less bass The higher bass output is the correct setting to use Another alternative is...
Page 6: ...inate or prove which component if the problem Left or right amplifier If both probably the source unit Try another source If one amplifier is distorted check the bias No bias reading means either a fuse blown or a faulty valve Distorted sound at higher volumes may be because one of the output 845i valves is not working This could be due a faulty 845 or one of the MB845i internal fuses blowing A sy...
Page 7: ...ar in mind that your mains voltage fluctuations can affect your readings by up to 10 If all the valves are reading slightly high or slightly low this is usually due to mains fluctuation In this case no adjustment is necessary TIP If one or two valves are out of line with the average only adjust those valves to the settings of the others Showing a probe in output valve test point 4 Adjusting If all...
Page 8: ...nt bias Most people find it easier to do a course adjustment within 10 of 180mv and then do a final adjustment when the amplifier is fully warmed up If all is well there should be no more than a barely detectable hum from the speakers and the amplifier should sound OK when tested You may need to adjust the Hum Adj screw see section 6 6 If you cannot set up 180mv then the valve is probably faulty o...
Page 9: ...use It is not guaranteed for commercial Public Address use or use in other situations The guarantee becomes void if the unit has been modified in any way not approved by Icon Audio 10 Packing Instructions It is essential that the original box and packing be kept in good condition as this provides vital protection during transit Please do not write on box but use removable labels Should the origina...
