8. Questions & Troubleshooting
Q: “Where's the -20dB pad switch?”
Because the input attenuator precedes the tube gain stage, the input level control acts as a variable input
pad. It should be used to either reduce the level of a hot input signal, or to simply set the overall gain of
the preamp. For best performance keep the GAIN switch set to LOW. HIGH gain should be used only if there
is not enough gain with the INPUT LEVEL knob turned to maximum.
Q: “I am having problems with troubleshooting ground loops?”
Try and resolve any grounding issues in your setup by using dedicated cabling etc. If you cannot remove a
ground loop in your setup, you can disconnect the Signal Ground from the Chassis ground on the FORCE by
removing the Ground Lift jumper, as shown in diagram 4. It is labeled P4 on the circuit board.
Go to www.manley.com and read our extensive FAQ for more information about the care and feeding of
vacuum tubes!
®
Q: Why do I hear some hiss at the higher GAIN settings?
The input control is an ATTENUATOR, not a volume control. It is used to reduce the level of a hot signal, not
boost the level of a weak one. The default position on this control is FULL CLOCKWISE. Turning this control
up does not raise the noise level, but stepping up the gain DOES. The lowest noise performance is going to
be with the INPUT control fully CW (Clockwise), and with the GAIN switch set at the lowest setting (40db).
When set to the 50db gain setting, you might hear some hiss. (Gain can be increased to 60dB with the
internal jumper, which will also increase noise level)
Q: Why is my FORCE not completing its power-up cycle?
The FORCE utilizes a custom designed, sophisticated high voltage switched-mode power supply. This power
supply features protection circuitry to stop any damage being caused to itself. If at anytime the unit will
not power-up the protection circuitry may have been triggered. It is in protection mode if after switch-on
the power LED blinks for a fraction of second then after a pause it blinks again. The PSU is now in protection
mode as the supply is trying to reset. This condition will occur if the unit suffers excessive heat exposure or
there is a damaged tube or component. Allow the unit to cool and try powering-up again. If the protection
mode persists, the unit will have to be returned for service.
Useful Tips
Any poor mic connection will be extra noisy with phantom turned on. This goes for cables, patchbays, patch
cords etc. Avoid running mic signals through patchbays. Some patchbays “ground” all the “sleeves” which
can add a ground loop into your delicate mic signal.
Ideally, set up the FORCE in the studio near the mic and use a short mic cable. Why ? Microphones often
have “light duty” line drivers and you can lose an audible amount of signal in long cables. You can get the
best fidelity by having the Mic Pre close to the mic at the “cost” of having to walk into the studio to adjust a
level control. You also avoid almost all of that phantom power / patching problem because now you are
patching the line level output signal only.
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