FUSE
This is the A.C.’s (Alternating Current) main fuse and provides protection from outside A.C. fluctuations as well as power tube
failure damage. Should the FUSE blow, replace it with the same rating in a Slo-Blo type package. The Domestic 117V version requires
a 2.5 Amp Slo-Blo fuse. A power tube short or failure is often the cause of a blown fuse. Follow the cold start procedure mentioned in
the STANDBY switch section and watch the power tubes as you flip the STANDBY to the ON position. If a power tube is going bad or
is arcing, you will see it! Flip the STANDBY switch down immediately and replace the faulty power tube and the FUSE if necessary.
EFFECTS LOOP (SERIES)
These two ¼” jacks provide the interfacing patch points for your “rear end” processing needs. The
Effects Loop is basically a circuit bridge from the end of the preamp to the Driver stage, with the SEND interrupting the signal at the
preamp’s end and the RETURN feeding the power section just before the Driver tube.
Using this patch point usually ensures the best sonic performance as well as signal to noise ratio with your outboard processors. That
said, it is important to point out that this is a critical junction in the Fillmore’s circuit path and whatever is inserted here can have an
effect on the overall performance of the amplifier.
The Effects Loop is a Series Loop, meaning that the entire signal goes through it, unlike a Parallel Loop where a percentage of the
unaffected pure signal is taken around the Loop. Therefore, the quality of the devices used in the Loop and their performance is criti-
cal to achieving the best sound and performance from your amplifier. We recommend auditioning any processor with your amplifier
BEFORE buying it to ensure it delivers a good match in performance. One clue is price. Like in any segment of the marketplace, you
get what you pay for most times and there is a wide range of quality in regards to both build and sonic performance. While technology
has raced ahead and features are at an all time pinnacle, it is the sound and feel for which you’ve likely chosen your pure analog all-
tube amplifier. Therefore, we recommend a similar degree of discretion when it comes to choosing your processing devices. Ultimately,
what you insert in the middle of your amplifier’s signal path will have a lot to do with how it performs.
To connect your Processors:
1. Connect the SEND to your processor’s INPUT
2 Connect the RETURN to your processor’s OUTPUT.
Done.
It is always best to use the shortest cable lengths possible. If you intend to run very long cable lengths, use a buffer. Even though the
amplifier’s Effects Loop IS buffered, there can be some minimal sonic penalty the longer the cable length becomes.
Always use shielded, high quality cables to connect your processors to the Effects Loop.
One way to check the quality of your processors and also, match the levels, is this simple test:
Set up a sound without processors in the Loop. Listen to the sound and observe the feel.
Insert your processing into the Loop. Do the same.
Remove the SEND and RETURN cables from the Fillmore and if the sound gets better, or the level jumps up, you will know that either
your processor’s levels are too low, the quality is in question, or both. If unplugging the cables from your Effects Loop drops the signal
level, simply reduce the Input or Output Levels of the processors. Repeat the test until there is no or very little difference in levels
when the processors are inserted and removed again from the Effects Loop.
REVERB FOOTSWITCH
This 1/4” jack allows remote control of the Reverb via an optional Footswitch. You can obtain the
Footswitch through your nearest MESA Dealer or from us directly. You may also use any standard “tip to ground” latching (not mo-
mentary) type Footswitch to control the Reverb. The jack accepts a mono unshielded cable.
PAGE 11