Signal Levels; Main Outputs; Tube Bay - Mesa/Boogie Formula Pre Owner's Manual

REAR PANEL:

SIGNAL LEVELS:

(Continued)
it is possible to overload the RECORD circuitry - as well as the input stage of many consoles - with certain settings of the
channels and certain pickups.
NOTE: When the RECORD OUTPUTS are connected to a console, any loading of the MAIN OUTPUTS by connecting them to a
power amp or processor will produce a significant loss in signal at the RECORD OUTPUTS. This is because the MAIN OUTPUTS are
not buffered in an effort to retain all the tubular magic produced by the impedance combination that occurs at the Formula's MAIN
OUTPUTS and the tube power amp's input. After trying every conceivable buffering scenario with dismal results, we refused to
sacrifice one drop of the Formula's luscious tone for this one patching scheme.
If you must connect both RECORD and MAIN OUTPUTS simultaneously - here are some possible options to navigate this
toneful patching idiosyncrasy:
(1) Record in mono and send the live signal in mono by using one of the output channels RECORD OUTPUT and the opposing
channels MAIN OUTPUT.
(2) With one or both of the RECORD OUTPUTS connected to the console, connect the MAIN OUTPUTS to a processor instead of
a power amplifier. This will likely reduce the amount of signal loss at the RECORD OUTPUTS quite a bit - because there is less
loading effect on the Formula's MAIN OUTPUTS due to most processors' input stages being of a higher impedance.
(3) Use an external buffering device on the Formula's MAIN OUTPUT(s) to reduce the degree of loading. We plan to offer such a
device - Call our Customer Service Dept. for more information about availability of this accessory.
The Formula provides two output channels for feeding signal to either stereo power amplifiers, effects pro-

MAIN OUTPUTS:

cessors (see EFFECTS LOOP - presented earlier in the Rear Panel section of this manual) or even the effects return or power-in
REC
OUT
TIP
RING
SLEEVE
RETURN - R
LEFT RIGHT
EQ
MAIN
OUT
The MAIN OUTPUTS are fed signal from the three individual channel MASTERS as well as the final OUTPUT Level control located
at the far right on the Front Panel. As mentioned earlier, the channels are controlled simultaneously with the single OUTPUT control,
as this potentiometer is actually two syncronous pots in one. To control the output channels separately, they must be sent to two
different power sources and then controlled independently from there. In this type of set-up it may be necessary to lift the ground on
one of the power sources to prevent a ground loop. This application is most often seen when a pre-amp is used to feed two or more
power amps on a large stage where there is need for both back line and stagefront monitor cabinets.
The Formula uses five 12AX7A type dual triode pre-amp tubes for its' all-tube circuitry which are mounted horizon-

TUBE BAY:

tally and recessed in an easily accessible tube bay. In the unlikely event that you need to replace a tube, you may do so by simply
unplugging it from its socket and plugging a new one in. Since the tube sockets grab the pins on the tube rather firmly, it helps to gently
(Continued)
NOTE: Avoid OUTPUT level settings above 1:00 when using the RECORD OUTPUTS as
stages of self contained amplifiers. Thus the Formula is a stereo capable pre-amp with two identical
signals that appear at the MAIN OUTPUTS. For mono applications simply connect either of the MAIN
OUTPUT jacks to your power amp or processor. To use both MAIN and RECORD OUTPUTS in a mono
scheme simultaneously, connect opposing outputs (one channels' MAIN OUTPUT to your power amp -
the other channels' RECORD to your console...see NOTE under RECORD in the Rear Panel section).
rock the tube back and forth while pulling outward on the tube.
When installing the replacement, make sure that the pins on the
tube are not bent (you can straighten bent pins with a pair of
needle nose pliers) and line them up carefully before inserting
the tube.
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