Low Z

The Low Z-Mode setting is a new sound for the Electric Bass Guitar.

The sound is deep and driving and will really make a B string (or lower) come alive. And if you have noticed your E string falling off at the end of the neck, it can more than handle that also.

Great for the studio work, the noise is extremely low and the distortion is very low.

As a warning - the rest of your amplifier system is going to get more of the string fundamental frequency than normal. I hope it can handle it - you have been warned...

the Details

In the Low Z-Mode the impedance loading the pickups is very small which has some interesting effects. Of primary interest is the extremely low noise.

In engineering, external noise sources are normally separated into two different categories: voltage noise sources that couple to the circuit by electric field interactions and current noise sources that couple to the circuit by magnetic fields. Guitar and Bass pickups are usually good sensors of both electrical and magnetic fields. As a general rule you can think of 50/60 Hz hum as coming from magnetic fields. High frequency static is normally from electric fields.

In the Low Z-Mode the voltage noise sources are practically ignored. This type of noise source is normally responsible for more than half the noise generated in most environments.

Current noise sources will still be sensed by your pickups. Hum bucking pickups are well known for reducing the pickup of most of this stray magnetic field noise. They do not really reduce the sensing of the magnetic field noise but cancel the noise by picking it up two times, with each out of phase relative to each other.

There are other reasons why Low Z-Mode is low noise. Due to low resistance values, the thermal and excess noise generated by circuit components is very small. The remaining sources of noise, which were relatively small before removing the larger sources, now become the dominate ones; these low level noise sources are further reduced through the use of very high quality components.

Low Z Gain Adjustment: In the Low Z-Mode, the output level ( i.e. volume of response) will vary depending on the pickups used. Some pickups are constructed with stronger/weaker magnetic fields and more/less turns on the pickup windings. To make sure our design will work with virtually all pickups - we have included a gain adjustment for each pickup.

3ZB has a small adjuster on the lower side of the module, near the label. It is a 10 turn adjuster.

JZ3-JZ5D has an adjuster just behind the wire connector. It is a single turn adjuster.

This gain adjustment only affects the Low Z-Mode's gain. 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 audible. The increased volume is a commonly abused trick used by many bass guitar manufactures to make an active bass sound better than the passive bass. That is not the goal here - we are attempting to adjust the relative volumes of the Low Z-Mode when compared to the Mid or High Z-Modes, all of which are active modes. Adjust the relative volume to taste but make sure you do not clip the output level when you play really hard. If the output starts to clip the sound will have a distinct harshness to it.

In Low Z-Mode, the individual strings on your bass will no long "see" the effects of vibration in the other strings. This is like have a single pickup coil for each string. Of course, mechanical interconnections between strings, for example through the bridge or neck, will still exist and affect the sound. If you are a chord player, the lack of string interaction will lower the distortion. The reduced distortion is measurable and is within the normal hearing range but it is a fine distinction that may not be of significance to some players.