PROGRAMMING THE Z-MODE SWITCH (OPTIONAL)
The Z-Mode is an internal electronic switching system that connects different electronic loads to each
pickup which changes the way the pickup sounds. Changing the load electronically is an extension to a
traditional technique used to change the sound of a passive control setup. For example, many players will
debate whether for pickup type X whether a 250K volume pot sounds better than a 500K pot. The
summed effects of the 2 volume pots + the tone pot & it’s cap + your amplifier’s input loading in a
standard passive bass setup determines the electrical load on the pickups and thereby how the bass
sounds. By changing the pots you could change the loading a small amount and get a slightly different
The Z-Mode system extends this concept to allow larger variations of the loading and isolates the 2
pickups from each other to allow separate loading control. Now a broader selection of organic sounds can
be obtained from your pickups and you are not dependent on the loading of the amplifier that you are
plugged into. With the Z-Mode system, you will not lose the passive sound because the Mid Z-Mode
setting is a match to a standard passive loading setup. Initially players may prefer the Mid Z-mode
because they are most familiar with this sound but as you experiment with other load configurations you
will find musical applications.
The Z-Mode system includes a 3 position mini toggle switch so that you have 3 different load
configurations at your disposal. To change the pickup load configuration you simple move the switch –
the preamp reconfigures it’s self internally to the new mode. The factory settings for the Z-Mode switch
are Low, Mid and High Z-Mode loads applied to both the neck and bridge pickups; but you can change
what loading is applied to the pickups for each switch position.
Different players, musical styles and pickups work best with different loads. To give you the fullest range
of options each of the 3 Z-Mode switch positions can be programmed to select 1 of the 9 different Z-Mode
configurations shown in the table that follows. This allows you to get the best sound from your pickups for
your personal playing style.
For example, some pickups do not have much of a unique high Z-Mode response. These pickups have a
low number of turns in their coil windings and this creates a limited amount of inductance such that the
resonant peak is smaller and at a high frequency not easily heard. But these types of pickups have a
bigger separation in the sound of Mid Z-Mode compared with Low Z-Mode. For this type of pickup you
may want to reprogram up your 3 modes to be 1) Low, Low, 2) Low’, Mid, and 3) Mid, Mid to get more
interesting Z-Mode switch settings. With other types of pickups built with a different winding pattern you
might favor the High or High’ Z-Mode settings to get the most interesting sounds from your bass.
Note when 2 different Z-Mode combinations are chosen for the neck and bridge pickups the mixing
control (balance or volume pair) becomes more powerful and slight movements of your hand to select a
different location from the bridge to neck will have a larger impact on the sound. But the noise cancelling
ability of pickups is reduced because of the 2 different loadings, in this case pickup shielding may be
helpful (see our FAQs on-line).
Pro JZ Preamp Installation, Rev Nov-12 Page 4 of 4
Neck-Z-Mode Bridge Z-Mode Factory
1 Low Low X
2 Low’ Mid
3 Low’ High
4 Low’ High’
5 Mid Mid X
6 Mid High
7 Mid High’
8 High High X
9 High High’
Low’ is similar to low Z-Mode but even darker – i.e. the pickup signal has less high frequency content.
High’ is identical to High Z-Mode with 0 extra capacitance – in other words the extra capacitance has
been switched out. For most pickups this is as bright as the pickups can get based on their design and
The configuration of the Jazz’s Z-Mode switch’s current position is reprogrammable using a temporarily
installed external switch, which is removed after programming. This switch includes a connector plus
wires to allow the switch to be located external of the cavity. The 2 pin connector plugs onto the jazz
board (orientation does not matter) and the wires are feed upward and snaked out the cavity below the
plate. The plate should not be screwed down tightly while programming up the Z-Modes so that you do
not crush the wires.
Reprogram the Z-Mode switch load settings:
1) Place the Z-Mode switch in any of its 3 positions – you are going to program this selected switch
position to any one of the Z-Mode configurations from the above table.
2) Hit the programming button
a) The present Z-Mode number will be flashed on the LED
b) If the desired mode is already programmed into this switch position – simply stop for
approximately 5 seconds – you will see the LED flash fast and the programming operation will be
aborted leaving the Z-Mode in the present configuration.
c) If you want to change the Z-Mode setting, hit the programming button N times to program a new
mode into this Z-Mode switch position.
i) The LED will light each time you press in the button
ii) After you are done – stop for approximately 5 seconds – the LED will flash the count of the
iii) If you enter an invalid number of button presses, (10 for example) the LED will fast flash and
the programming operation will be aborted.
iv) If you move the Z-Mode switch during programming – the LED will fast flash and the
programming operation will be aborted.
After you have programmed up your Z-Mode selections – pull up the preamp, remove the programming
switch and store it so that you can reprogram the Z-Mode selections in the future if you want to, then
simply re-install the preamp without the switch.
Our website has extensive information on the preamp and installation, including FAQs.
LESSONS = GAS killers!