Vol, Vol, Z-Mode switch

3 Z-mode preamp + Tone for Jazz Style Basses with the Jack on the Body Side

The JZ3D models are an expansion to our popular JZ3 preamps. The preamp has been upgraded by adding a passive type of tone control in the 4th hole. Many players favor this traditional type of high frequency tone control.

To make the JZ3D preamps as affordable as possible, we have simplified the control options, 2 models are offered:

Volume, Z-Mode switch, Mid/Balance stack, Treble/Bass stack, LED meter, & Output Jack (not shown) or
Volume, Z-Mode switch, Volume, Treble/Bass stack, LED meter & Output Jack (shown in photo)

JZ3D-VV front side

All of our JZ versions use the same high quality design and components as our 3ZB configurable preamp and have the LED battery level indicator. Most important, they both feature our Z-Mode Impedance level control, delivering 3 organic bass voices with clarity and definition.

Further on you'll find more information about these additional features:

Low Z gain adjustment with single turn pots and
High Z Capacitors that are socketed so that you have the option of changing their value, optimizing the Frequency peak location.

Installation is easy: remove your old plate and side jack, insert the new switched jack into the side of the bass, insert the pickup wires into the green connector and tighten the screws, attach the ground wire to your bridge & cavity ground wires with a crimp connection, insulate the crimp connection, drop the battery and plate into the cavity (take care here to be sure the battery is positioned in the board cut-out and no wires are trapped) then screw in the 3 plate screws. In some installations you will need to solder connections to the batteries in your existing battery box. For more info read the Installation Instructions.

JZ3D-VV back side

Plate Mounted Jack? If your jack is in the plate please see our JZ3 Preamp.

Standard Sized Cavities

The current American Fender Jazz Bass has a cavity that measures approximately: 1.19"wide at the top (some cavity narrow slightly at the jack end), 1.27" deep, and 5.17" long.

Most jazz style basses including current Fenders made in Mexico and Japan have this same cavity size. A few other bands may be different and some older Fender basses, especially vintage models, may vary from these dimensions.

When you check the size of your cavity, our preamp needs cavity dimensions of: 1.1" wide, 1.2" deep and 4.8" long.

Volume Controls

The standard knob configuration for a passive Jazz Bass is volume, volume, and a treble roll off. If you like having separate volume controls for each pickup then we offer separate volumes with Treble and Bass active tone controls.

The standard configuration for most active basses includes volume and balance controls. If you like this configuration then we offer this with Treble, Mid and Bass one controls. You will notice, our balance control is actively buffered so it will be very smooth in it's operation as you pan between the pickups.

More info - JZ Volume Controls

Tone Controls

In the JZ3D product you get either a 2 or 3 band tone control depending on configuration

2 band tone controls:
Bass is shelving +/- 13 dB at 100 Hz
Treble is shelving +/- 14.5 dB at 2.5 KHz

3 band tone controls:
Bass is shelving +/- 12 dB at 80 Hz
Mid is wide bandwidth +/- 10 dB at 470 Hz
Treble is shelving +/- 10 dB at 3.7 KHz

All the tone control pots are centered de-tented where the response is flat.
More info - JZ Active Tone Controls

Passive Style Tone - JZ3D only

The passive style tone control on the JZ3D preamp performs a high frequency roll off like a traditional passive type tone control. Many players love the effect this control has on their bass tone and have a great deal of experience in how to get the best from it.

Battery

The preamp operations off a standard 9 volt battery. A high quality battery should last just over 300 hours in this preamp. We ship a battery with the preamp. More info - Battery FAQ

All of our preamps feature a very useful LED battery power meter. The meter operates when the cable is first plugged in to let you know about the batteries status. More info - JZ Battery Meter

Flexibility

Replaceable capacitors - Pickups vary in their signal response and most have a high frequency peak when loaded with a high impedance (you can read about it on our High Z page). The JZ3 allows you to change the location of that peak in High Z-mode by changing the amount of capacitance loading the pickup in the circuit, independently for each pickup. Each pickup channel has a socketed capacitor that can be changed, which changes the location of the peak frequency. You can see a bridge cap in the picture on the right. Optimized for stock US Fender Jazz pickups, JZ3 comes with 660 pF (encoded as 681) loading the neck pickup and 330 pF (331) loading the bridge pickup. To make changing your pickup's high frequency peak location we offer a kit of 10 cap values as an option.

Gain adjustment - In the Low Z Mode, the signal response of pickup changes 10:1 depending on how the pickups were constructed. The picture to the right shows a gain adjustment for the Low Z-Mode. If you want more gain, turn the gain adjustment for that pickup clockwise. If less gain is required turn counter clockwise. It is a relative gain control - it does not affect the frequency response of the pickup but due to the way humans hear we need lots of volume or sound pressure level to hear low notes. So adjusting the gain up will make your bass appear to be getting lower when actually it is just making the existing lower frequencies more audible. This is why this adjustment is for Low Z only. Stock US Fender Jazz pickups have the correct gain when the control is set to about 9:30 and this is how units are shipped.

Already Changed Out Your Pickups?

Our technology works great with all of the common upgrade pickups except active EMG pickups. Common customer replacement pickups we see include Nordstrand, Bartolini, Fralin, Basslines, DiMarzio and various forms of the Fender custom shop pickups.

NOTE: To use our preamp, you must have PASSIVE PICKUPS, meaning that the pickup does NOT have a semiconductor component in it (transistor, op-amp etc). If you are uncertain about your pickups, check with the manufacturer or send Sales an email

There are additional details on the controls and installation in the FAQs.