Manley MASSIVE PASSIVE STEREO TUBE EQ - MSMP 1998 - 2/2004 - Manual (Page 17)

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 (for voltage gain) and 6414 (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: See on the diagram above the "AC VOLT CHANGE". Soldered jumpers have to be
changed. ABSOLUTELY BE SURE THE AC IS UNPLUGGED AND THE UNIT HAS BEEN GIVEN AT LEAST 15
MINUTES TO DISCHARGE! First the electrolytic capacitor marked "ACCESS" has to be desoldered and removed
temporarily to have access room to the jumpers. This cap normally has 350 volts on it and takes at least 15 minutes to discharge.
It may be difficult to desolder due to the large trace area on the PC board. Do not damage the board and plate-throughs.
For 110 to 120 Volt Mains: Jumper A to C, and Jumper B to D. These jumpers must be insulated preferably with Teflon Sleeves.
For 220 to 240 Volt Mains: Jumper B to C (only) This jumper must be insulated preferably with a Teflon Sleeve.
Re-install the electrolytic cap that you removed being careful that the PIN stamped "+" is towards the front and the PIN stamped
"-" is towards the back. Do do trust the "------" marked on the cap label (sometimes it is slides or is wrong).
4) Changing the 1/4" phone jacks for -10dBv levels: The Massive Passive is factory wired for professional +4dBu 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" implies +4dBu 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, including +4, -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 6414 6414 6414 5751 5751
F F F
F
F F
F
AC VOLT CHANGE
A B C D
ACCESS
GAIN TRIM
+4 / -10 CHANGE
GAIN TRIM
+4 / -10 CHANGE