1) To Open: Disconnect the AC Power cable, let sit 15 minutes to allow the power supply capacitors to discharge. Remember
there are high voltages (300VDC) used in the Massive Passive and that the capacitors may continue to hold a charge after power
is removed - BE CAREFUL! We suggest using gloves and/or "one hand only" when the top is off.
Remove the single Philips Machine screw located on the top perforated panel (towards the back and center). Slide the perforated
panel towards the back.
2) Replacing Tubes: The tubes are marked as to their type 5751/12AX7 (for voltage gain) and 6414/12BH7 (for line drivers).
Another warning: Tubes get HOT. Let them cool before you attempt to touch them. Wiggle the tube back and forth as you pull
it up. If you suspect a tube, you can swap it with the other channel. If the problem follows the tube, you were right, it is that
tube. If not, try swapping another pair of tubes. It is a good idea to have a few spare tubes for emergencies as this will fix better
than 90% of most problems.
3) Changing AC MAINS VOLTAGE: Disconnect the AC Power cable. See on the diagram above the "AC VOLT CHANGE".
Use a small flat screwdriver set voltage change over switch to 120VAC or 240VAC operation. Replace main Fuse with correct
type and value. For fuse information refer to Pg. 29..
4) Changing the 1/4" phone jacks for -10dBv levels: The Massive Passive is factory wired for profes4dBu levels for
both all of the XLR and 1/4" phone jacks. This procedure only changes the 1/4" jacks - not the XLRs. Do not assume that
"balanced" i4dBu levels or that "unbalanced" implies -10dBv consumer levels. Balanced only means that there are 3
wires in the cable and that 2 of these wires carry signal in opposite phases and that the same impedances (source especially)
exist. Unbalanced refers to a cable system with two wires (signal and ground). "+4dBu" refers to professional signal levels
(0VU=1.228 volts AC into 600 ohms). "-10dBv" refers to consumer signal levels common to hi-fi and low budget semi-pro
gear and is typically 14 db lower than pro levels. The common connector is the RCA style phono jack. 1/4" jacks are used for
a wide variety of signal types and levels, inc4, -10, instrument Hi-Z and speakers and headphones. 3 conductor plugs
are used for balanced signals, inserts (send and return) and stereo (L&R) which tend to be incompatible. Simply plugging in
a 1/4" to 1/4" cable from one piece of gear to the next is not guaranteed to work. You may have to check the operators manuals
if you run into problems.
See the diagram above for the DIP SWITCH locations and the next page for a closer look.
17
THE GUTS
6414/12BH7
5751/12AX7
AC VOLT CHANGE
GAIN TRIM
+4 / -10 CHANGE
GAIN TRIM
+4 / -10 CHANGE
6414/12BH7
5751/12AX7
6414/12BH7
6414/12BH7
