JAD FREER AUDIO SISMA Manual

MANUAL
Latest update December 2023
Thank you for purchasing a JF Audio product! Your amp has been carefully hand-made in Italy, using
only the best parts available.
It is our hope that this amp will become a mainstay of your rig for many years to come.
With this document, JF Audio ensures you a life-time warranty against defects in materials and
workmanship; external parts like pots, jacks and switches have a 24 months warranty. In the event
that your product becomes damaged, contact JF Audio and you will receive instructions on how to
go about having your amp repaired.
SISMA BASS AMP
The SISMA is a powerful, compact, bass amp featuring a traditional voiced tube preamp
and passive tone stack, paired with active semi parametric eq and a Class G transistor
power amp fed by our proprietary switching power supply.
FRONTPANEL CONTROLS & FEATURES
INPUT This 1/4"6.3mm) jack is the mono instrument INPUT, connect your bass (or mono
source) here! The signal will be processed by the preamp and will be present at DI out,
SEND, LINE OUT, PHONES and SPEAKER OUT. Imput impedance is 2.2 MOhm.
AUX This 1/8"(3.5mm)jack is ready to be fed by an external source like a mp3 player. The
stereo signal is summed in mono and amplified with a fixed gain. Overall volume is
controlled by the MASTER control. The signal will be present at PHONES out and SPEAKER
OUT (but not at DI out).
MUTE Mutes the signal. You can still use the PHONES out for silent practice.
LPF This switch activates a low pass filter that gently cuts the very high frequencies
of the signal, think of it as taming the tweeter sound of your bass cabinet. This filter
helps in cutting some unpleasant sounds when using high gain levels, its tailored to be
used also with a clean sound without making it dull or dark. When using it with certain
instruments (old school dark basses) or cabinets (sealed or tweeter-less) it may seem
that this control does not do anything, this is because the curve is gentle enough not
to mess with your core sound.
DEEP This switch provides a perfectly tailored bottom-end boost. The enhancement has
been tested to be just the right amount of musical bass response, adding fatness without
mud.
GAIN This logarithmic pot controls how much of the first tube stage goes into the second
tube stage. You can start around noon and turn counter-clockwise for a clean and fast
sound or clockwise for a more fat sound. High gain settings result in a pleasant