Pro Z Preamp Series - Frequently Asked Questions

Compared to a JZ3, JZ3D, JZ5D, JZ6D, Pro JZ3, Pro JZ3D or Pro JZ6D  Preamp - how is the Pro Z preamp different?

We are happy that you have one of our jazz preamps...

The Pro Z preamp is a configured module preamp so the preamp is in a small plastic case and the pots are on wires so they can be moved around based on the holes in your bass body.

This preamp series include the Z-Mode system which is re-programmable like a Pro JZ3.

The Advanced LED Battery Meter is present on this preamp series.

It will have the touch response so many players love about our systems.

The Tone controls will be the similar - same quality and S shaped response curves etc.

You must solder the pickups to the input wires.


Compared to a Classic Preamp - how is the Pro Z preamp different?

We are happy that you have one of our module preamps...

This preamp series includes the Z-Mode system - it sounds just like the Classic in the Mid Z-Mode setting.

The Advanced LED Battery Meter helps you know the state of your batteries' charge.

It will have the touch response so many players love about our systems.

The Tone controls will be the the same - same quality and S shaped response curves etc.

Only passive pickups are recommended with this preamp - note almost all basses use passive pickups even when they contain a preamp in them.


How does the Advanced LED Battery Meter work?

Video of how the Advanced LED Battery Meter works in a Pro JZ3 preamp which has the same system.


My package includes an extra battery clip?

There is normally no significant benefit to running Audere preamps on 18 volts since we do not put large amounts of gain in our preamps like many other vendors do.

However if you play very aggressively with loud pickups and lots of tone control boost then you my want to convert to 18 volts.

The extra battery clip allows you to re-wire the preamp to run on 18 volts.

Connect the 2 battery clips in series by cutting the red wire shorter on one of the clips and black wire shorter on the 2nd battery clip.

Stripping the ends of the cut wires and soldering the first black to the 2nd clips red.

The pair to battery clips will now have 2 free ends - one red and one black.

The red goes to the red wire coming from the preamp.

The black goes to the short black wire coming off the jack's ring connection.

Insulate the connections with heat shrink when done.



Will this preamp fit into my Bass Electronic Cavity?

Probably - the preamp easily fits into most cavities.

The module X dimension is 2", the Y dimension is 1.05" and the Z dimension is 0.3"





Our custom pots are higher quality and smaller than the typical parts used in guitars.

The body is the same size for the single and stacked pots but 2 sections are included with stacks so the pot will extend farther into the cavity.





How is the preamp module mounted?

We supply double sticky foam tape to mount the preamp to the side of the cavity wall.

If you are low on space the preamp can be mounted to the backside of the electronics cover.


Electrical connection to wires on the back of the preamp?

The wires on the back of the preamp must not touch an electrical conductor like copper shielding or conductive paint in a cavity.

This is normally not required but you can cover the wire ends with electrical tape as an insulator if needed.



How do I Solder Ground Wires to the back of the Pots on the Circuit Board?

Do not attempt this - crimp or solder all the ground wires and pickup commons together with the gray/white wire off the jack.

FYI - soldering to the back of pots was always a bad idea, even in Leo Fender's days...


Will it work with coil tapping switches?

Make sure no wires go from the coil tapping switches to ground.

Any ground connections should be connected to the Green/white pickup common connection which must not be connected to ground.

Special note - a separate coil tapping switch for each pickup can be nice.


I have a PJ - Will it work?

I have a J Hum-bucker - Will that work?

Yes to both, and it will sound great - our stereo front end separates the P and J inputs (or J and Hum-bucker) so they sound better.

You might want to reduce the volume of the P relative to the J with the gain controls to balance them up better.

If your J pickup is not a Hum Canceling type of pickup then the Hum will increase as you turn the balance toward that pickup.


Does this preamp work with Hum Canceling pickups?


Note - shielding hum canceling pickups is often overlooked and important to get the lowest noise levels.


Is shielding the pickups a good idea?

Always if well done and it can reduce the noise in a lot of cases.

One thing we commonly see done incorrectly on shielding is not grounding it correctly - non grounded shielding is an antenna for noise.


Which wire color is pickup Hot?

It completely depends on the pickup maker and version - so check their website.


Can I Install the Preamp myself?

Maybe about 50% of this model are installed by players - see the Instruction PDF


How long does it take to get my preamp in the US?

We normally ship in 1-2 business days, but we do not control the postal service and how long they take to deliver the product but they have been surprisingly fast on average.

We ship first class mail, if you want to upgrade to US. Priority there will be a shipping adder.

You will get an automatically generated email when we ship.


How can I get it Overnight?

Sorry - we do not ship overnight - FedEx, UPS and USPS have been very poor at overnight delivery and it created too many problems.


Can I get it Delivered by FedEx or UPS?

Sorry - we no longer offer UPS or FedEx shipping.

USPS has not been perfect but on average they have given our customers the best results.


I have Upgraded Pickups by --- will it work?

Aero, Aguilar, Barts, David Allen, Delano, DiMarzio, Jason Lollar, Lakland, Lindy Fralin, Nordstrand, MEC, Seymour Duncan, etc. all build good pickups of slightly different flavors and work well with our preamps.

For Delano you may need a 3 wire version so the pickup common is separated from the pole piece ground. All Delano pickups can be purchased in the 3 wire configuration.

There are a host of other pickup winders I have not listed - no offense meant - in almost all cases they work too...


Do AlNiCo, Ceramic or Neo pickups work better with the preamp?

All the different magnetic types work well and sound slightly different from each other.

Personally I like AlNiCos but select what type sounds best to you.


I have a PJ - Will it work?

I have a J Hum-bucker - Will that work?

Yes to both, and it will sound great - our stereo front end separates the P and J inputs (or J and Hum-bucker) so they sound better.

If your J pickup is not a Hum Canceling type of pickup then the Hum will increase as you turn the balance toward that pickup.


Which wire color is pickup Hot?

It depends on the pickup maker and version - so check their website.


The Pickup Input Connections?

All pickups still have a pickup hot and pickup common connection; for this series of preamps; the pickup commons must be connected to the Green/white wire and isolated from ground.

If the pickup common is not isolated from ground then all hell will break loose - the Z-Mode switch will pop - the preamp may shutdown etc. These problems aren't damaging the preamp, it will all stop when the pickup common is isolated from ground.

The Z-Mode Preamps to use a Direct Current (DC) coupling to the pickups - most preamps use a capacitor on the front end so the pickup commons are connected to ground. To create the Low Z-Mode response it was not possible to have a large enough capacitor to allow the pickup commons to be grounded. Well actually this is not quite correct - it was not possible to get a big enough capacitor using a high quality metal film capacitor instead of a type of capacitor which would add an artificial sound due to distortion.

So in the end what we need is to have both ends of the pickup coil(s) wiring to be connected to the preamp's input wires.


My pickup has 1 White Hot and 2 Black Grounds...

My guess is you have an older Aguilar pickup based on our current experience when we get this question but you might have a different pickup.

One of your blacks will be the pickup common and the 2nd one with be a ground from either internal shielding or to ground the pole pieces.

This is a simple test you can do to see which wire is common and, if so, should be connected to the input connector common terminal.

Proceed forward one pickup at a time.

Connect the White (or yellow) Hot to the input wire - Black/white for the Bridge, Blue/white for the Neck.

Isolate both Blacks by putting them in air not touching anything.

If the 2 black wires look different - choose the one with the that looks similar to the Hot wire as the common input and connect it to Green/white.

Power up the preamp with your amp at a low volume.

Pluck a string - if no output - swap black wires, isolating the unused wire.

One or the other black wire will work as pickup common.

Now connect the 2nd black wire to ground along with the bridge wires etc.

Test - verify the Z-Mode switch does not pop like gun fire when switched.


Alternatively, if you have a DMM it will be faster to do a simple resistance test to identify the wires.

Put you DMM in resistance mode.

Connect the Red Probe to the White Hot wire.

Measure the resistance to each Black wire - one will be 5K to 15K ohms and this is common - the other one will be infinite, or no reading, and this wire should be grounded.


What does Z-Mode do for me?

The effect the Z-Mode system achieves is like having the same bass with different pickups installed and selectable.

Now if you were going to have 3 different identical basses on stands to choose from - the first would probably have traditional sounding pickups, the second probably a darker set and third a brighter set - so the JZ3 preamps are setup this way by default.


How does a Z-Mode Switch work?

Let's start with what it is NOT - most players think it must be some type of tone control curve, for example, like a slap switch which is just a high frequency boost.

The effect of the Z-mode switch is like having the same bass with different sets of pickups installed into it.

A pickups frequency response curve (sensitivity or output voltage vs frequency) is determined by many things - the distance from string to pickup, the string type, the magnetic field created by the magnets, how the coil was wound and what electrical system loads the pickups. It is the electrical loading component that the Z-Mode system changes. Even in a passive setup you have an electrical system loading the pickups - the control pots have a resistance, capacitance is present from leakage to the tone pot cap, the cable is a significant capacitor, and the input to the power amplifier is often a complex loading. All these things effect the sensitivity of your pickup to the string's movement.

In all of our preamps, we control the loading on the pickups and we do it before the pickups are mixed together. This creates two principle advantages - 1) We improve the sound quality and get rid of a lot of unknowns like what type and condition your guitar cable is in, which amp are you plugged into, etc, and 2) by switching the loading we change the pickup's response curve.

Our non Z-Mode preamps and the Z-Mode preamps in Mid Z-Mode create a very classical passive loading - so you get a response like a very high end passive setup (IE. one which would cost you a lot more than the preamp).

Our first generation Z-Mode preamps had a Low Z-Mode setting that sounds like more bass but does not get muddy like overly boosting the bass tone control; it also had a High Z-Mode setting with a peak in the upper mid to lower treble range.

Our current Pro JZx preamps have further extended the system by optionally allowing the switch selections to be user programmed to one of nine (or more) combinations on the pickups. Most users never get around to programming up the switch because they like the defaults but combinations like Low' Z-Mode on the Neck (deeper) and High Z-Mode on the bridge (brighter) are interesting options.


What is a typical Pickup response in each mode?

The following curves were generated with a Fender single coil AlNiCo Jazz pickup but most pickups will closely follow these patterns.

The tone controls were all in the center detents which has a flat response.


Mid Z-Mode response - sounds like a passive Bass with the Tone knob all the way up

Low Z-Mode response - has more low end. This pickup is connected to the Neck input with our default Neck Pickup gain adjustment.

The output level (as opposed to curve pattern) of pickups varies a lot depending on the number of wraps in the coils so there are independent gain adjustments for each pickup for this mode.

This response curve is similar to what is created when a pickup maker significantly increases the windings in a pickup, a Seymour Duncan 1/4 Pounder is a good classic example.

High Z-Mode Response - has a peak in the upper mid range to lower treble. Again this pickup is connected to the Neck input with our default 680 pF capacitor.

The High Z-Mode response shows the most difference between pickups with variations in both the magnitude of the peak and it's exact frequency.

This response curve is similar to a pickup which is specially wound to have especially low capacitance in the winding, for example, some MEC Jazz pickups and lots of standard guitar pickups.

So what we did was to take your bass and give you the equivalent of at least 3 different sets of pickups to chose from, depending on what you need at the time.

What normally happens in the guitar world is a pickup maker varies the windings and selects materials which effect inductance and capacitance to create different sound profiles against a standard load - we flipped this equation around and varied the load part of the equation to get different sound profiles without changing the pickups.

Our system is more complex for us to make but gives the player more versatility.


Many players spend the majority of their playing time in Mid Z-Mode but the other favors are available at anytime on the switch. If you do not need the increased versatility then you should check out our Classic Series which are lower priced.


What adjustments can be made to the Z-Mode System?

The following adjustments are all optional.

This picture below is showing you where the adjustments are located on the preamp - then we will describe each adjustment in more detail.

The first and most common adjustment players make is to set the Gain of the Low Z-Mode setting. There are separate pots for the Neck Pickup's gain and the Bridge Pickup's gain.

Next, the Capacitors of the High Z-Mode setting can be changed - there are two caps, one for each pickup.

The third adjustment is made with the center programming switch and is used to reprogram the Z-Mode Switch settings.



How do I Adjust the Low Z-Mode Gains?

Most players will not need to adjust the Low Z-Mode setting but it depends on your pickups and desired output level in the Low Z-Mode.

Using a small flat screwdriver - Individually rotate each pot counter-clockwise to reduce the gain (sound level) or clockwise to increase the gain.

The frequency response curve shape is the same at any gain level but your ears may think otherwise due to our non-linear hearing.

You can adjust each pickup as desired - the goal is to roughly match the Mid Z-Mode level for each pickup.

Set the tone controls in the center detents (flat) and, if present, the passive tone at the max setting (flat).

Move the balance or pair of volumes to solo the first pickup at the max output level with the second pickup at minimum.

Set the Z-mode switch to the center position and listen to the level.

Next, move the Z-Mode Switch to select Low Z-Mode - adjust the correct pot for the soloed pickup and adjust based on the volume level you heard in Mid Z-mode.

Repeat the comparison and adjust as required.

Now do the same process for the other pickup.




What changes do the High Z-Mode Capacitors make?

Players often ask if this is like a high frequency roll off cap - no, this is a different concept.

Pickups have a peaked response in High Z-Mode. The frequency location of the peak can be changed to a lower frequency by adding external capacitors.

We per-installed what we think are optimal values, a 680 pF cap to load the Neck Pickup and a 330 pF cap for the Bridge Pickup.

The graph shows the change in the magnitude and location of the Peak when loaded with 2200 pF down to 0 pF for a standard single coil Jazz Pickup.

The actual caps used were 2200 pF, 1500 pF, 1000 pF, 680 pF, 470 pF, 330 pF, 220 pF, 100 pF, none or 0 pF which is the values in our Cap Kit.


How to Extract and Install different High Z-Mode Capacitors?

A strong wooden toothpick is a good tool to help remove the capacitors.

Slide the toothpick under the capacitor.


Push down on the toothpick free end to leverage up the Capacitor. It will take very little force.

Installing new Capacitors is very easy - push down on the top of the Cap when the Cap Leads are in the Gold Sockets on the Preamp Board. Be sure there are no burrs on the capacitor leads.


How do I Program the Z-Mode Switch settings?

Most players never change the programming defaults on the Z-Mode switch but you can experiment if desired.


The Battery must be installed and a mono plug must be inserted into the jack to power up the preamp.

Put the Z-Mode Switch into the position you want to change.

Click the button. Some times a small soft object will help you depress the switch which is in-between the 2 pots.

The present Z-Mode Code number programmed into the switch will flash on the LED as shown on the programming sheet. For example, 1 flash is Low, Low Mode on both Pickups, 2 flashes would be Low' on the Neck Pickup, Mid mode on the Bridge Pickup etc.


If you want to keep the present Z-Mode Code already selected for this switch position then do nothing for 5+ seconds. The LED will fast flash, cancel the change sequence and the Z-Mode setting will not be modified.


If you want to change the Z-Mode Code, say to 3 for example, then click the switch 3 times. Wait for 5+ seconds so the system knows you are done. The system will flash back the LED 3 times so you know the setting was changed to Z-Mode Code #3 and the sound of your bass will be changed when you play it.


You can Program each of the three switch setting as often as you like. The changes will be retained if you disconnect the battery.


Video of Programming the Z-Mode Switch


When using a different Z-Mode on each pickup the hum or noise increases?

If you have single coil pickups then the 2 pickups with different frequency response curves will not cancel as well when mixed together at equal volumes.

If you have hum bucking pickups then the cancellation will only be reduced slightly or may not be noticeable.

Improved pickup shielding will be helpful for both types of pickups.


How many Bands of Tone Control is most Popular with Players?

The 4 band is the most popular option.


Why do I need a 4 Band Tone Control?

Four bands of tone control makes it easier to dial in the tone you want quickly but some players prefer 2 or 3 bands.


Why does a different number of Tone Control Bands change the price?

Each configuration is a unique circuit board - designed to optimize the performance for a specific configuration.

The increased number of tone control bands requires more parts - so we charge a minor difference in price to cover for the extra cost to build the preamps.


What is the difference between a Pan, Blend and Balance Control?

They are the same thing.


How does a Passive Balance compare to an Active Balance?

Passive balance is traditional (and lower cost) but lacks the note definition and control of an active mixing system.

Active mixing is not new - it has been used for a very long time in all kinds of critical music applications during studio recordings.


Does the Balance control have a Center Detent?

Yes - in the detent position the 2 pickups are mixed into the output equally.


Do the Tone Controls have a Center Detent?

Yes - the frequency response is flat in the detent position.


Can I get it with a different style of knob?

No - we do not have other knobs.

If you want you can replace the stock knobs, just be sure your own knob set fits the pots.

The singles and tops of stacks are 6mm shafts.

The bottoms of stacks are 8mm shafts.

All shafts are round holes - so a set screw is required to hold the knob on.


How long does the Battery last?

A high quality 9 volt battery will last about 250 hours plugged into most bass amps.

If you are plugged into a lower ohm load - most common is directly into a  line level recording interface - then the preamp will need more power to drive the output signal to full frequency response so your battery will have a shorter life but you are getting a higher quality recording so not a bad trade-off.


Why is a Battery not included?

In the past we shipped batteries with the Z-Mode preamps but shipping rates have continually increased and the battery pushes the weight up to a different class of postage so there was a significant price jump.

So at this point is makes more sense to have you supply the battery so that we can offer you the product at a lower total cost.


Do I need to put in a Battery Box?

No - Normally the battery fits in the electronics cavity near the module.


Can I hook it up to my Battery Box?

Yes - un-solder and remove the battery clip

Next solder the wires to the red (+) and black (-) connections on your battery box.

Insulate the wire joints when you are done.

A 9 or 18 volt battery box system can be used.


Can I get it with a Long Threaded Body Jack?

Can I get it with a Neutrik Locking Jack?

Sorry there are too many different jack types for us to supply all of them and for some types they are hard to replace.

But if you have a stereo jack (common) then you can move our wires over to your jack.

The white is the tip connection (preamp output)

The black is the ring connection (negative side of the battery which is connected to ground by the mono plug to power up the preamp)

The Grey/white wire is the ground(s).


Does 18 volts create a Higher Output Level or Help in some way?

18 volts has the same output level as 9 volts.

If you adjust up the pickup gains and use a LOT of tone control boost then it might help.

Most players do not need to bother with 18 volts; our electronics work great on a single battery.


Why are some of my other Active Basses Louder?

Many players will own basses that have more output gain than our preamps but this extra gain comes at the cost of modifying the sound quality.

At reasonable volumes, a louder bass sounds better because its easier to hear the high and low frequencies - but if you make the volume level equal by using your amp and then compare it to the passive/original tone you probably will not be very impressed.

We are not trying to trick you into thinking our preamp sounds better than your passive bass by pumping up the volume. We want your bass to retain the full passive tone of the pickups while making it play better and easier to use on stage.

Since all commercially viable bass power amps work well with a passive jazz bass (more of these are sold than any other type of bass) your bass amplifier should have plenty of power to drive the speakers.

If your bass amp has 2 inputs - use the passive input with of our preamps.

The active input reduces your signal to the same level as a passive bass and then uses this signal as the source for the rest of the amplifier.

If you bass amp has only one input with a gain adjustment then set it like you would for a passive bass input.


How do I make it Sound like a Passive Bass?

Put the Z-Mode switch in Mid Z-Mode for both pickups (by default the Z-Mode switch will be in the center) and the Tone controls in the center detents which are flat.

We do not have the distortion which most preamps do so we won't mess up your tone.


Can I add an Active/Passive Switch?

You can get a limited functionality A/P switch but installing one is never recommended.

The P mode will not have a balance feature.

But our design addresses the most common reasons players want an A/P switch which are:

1) Sound issues - we do not screw up your sound with a lot of distortion.

2) Battery issues - we have a LED battery meter.

3) Electronic failure - adding a switch reduces your reliability, it doesn't improve it.


Will this work with my Pedals?

Probably - most pedals are designed for passive input levels and this preamp will play nice with them.

In a very few cases some pedals may not like that we drive the cable from a lower impedance source than a passive pickup.

We drive the cable harder to avoid external noise pickup by the output cable but if this causes you issues with a pedal, which is unlikely, then email us and we will expaln how to add a resistor to the output jack way to raise the output impedance.


Will the preamp produce Hum?

The preamp will not produce hum - it runs off a battery as opposed to a 50/60 cycle power line but the preamp will pass through hum collected by the pickups.

Single coil pickups will naturally hum when the levels are not equal or in the rare case that your pickups are not RWRP pickup windings.

Normally the levels will be equal in the center detent of the balance control but this can be changed when the gain adjustments are not set equal or when a pickup maker has increased the windings on a Bridge pickup to boost its volume up (the string movement is less at the Bridge pickup location which creates a lower volume).


Is shielding the pickups a good idea?

Always if well done and it can reduce the noise in a lot of cases.

One thing we commonly see done incorrectly on shielding is not grounding it correctly - non grounded shielding is an antenna for noise.


Does this preamp work with Hum Canceling pickups?


Note - shielding hum canceling pickups is often overlooked and important to get the lowest noise levels.


I will be traveling from overseas to the US for business or a vacation - can I have the preamp shipped to my hotel?

Possibly with reasonable lead time - email us with your plans - assuming someone can sign for it (most hotels will do this) then it is probably possible to work it out.

Note we are only responsible for the preamp till it gets signed for at the delivery point.


What is the Frequency Response of the 2 Band Tone Control Option?

We use shelving controls for all Treble and Bass tone controls so the specs look different than other manufacturers.

Our specified frequency point is at the 1/2 boost or cut frequency.

The 2 band tone control specs are Bass 200 Hz +/- 18 dB and Treble 2.0 KHz +/- 17.5 dB.


What is the Frequency Response of the 3 Band Tone Control Option?

The Mid Tone control spec is 500 Hz +/- 10 dB.

We use shelving controls for all Treble and Bass tone controls so the specs look different than other manufacturers.

Our frequency specified point is where the 1/2 boost or cut frequency occurs.

The 3 band tone control specs are Bass 200 Hz +/- 16 dB and Treble 2.5 KHz +/- 16.0 dB.


What is the Frequency Response of the 4 Band Tone Control Option?

The Low Mid Tone control spec is 250 Hz +/- 10 dB.

The High Mid Tone control spec is 750 Hz +/- 10 dB.

We use shelving controls for all Treble and Bass tone controls so the specs look different than other manufacturers.

Our frequency specified point is where the 1/2 boost or cut frequency occurs.

The 4 band tone control specs are Bass 180 Hz +/- 16.0 dB and Treble 3.2 KHz +/- 18.0 dB.


What is a Passive Type Tone?

A passive type tone is a high frequency roll off circuit.

It is like the 3rd control on a standard passive jazz bass.

When you max the control all of the high frequency content is present in the output signal.

If you turn the control to the min position a bass will get very dark with little high frequency in the signal.

At an in-between setting the effects are more complex.

Many players love this type of high frequency control and it is available on the side mounted jack versions of the preamp.


I can-not hear a change from the Treble Tone Control.

When I turn it up the Bass Tone Control it causes a lot of distortion.

Most likely you are testing with an inexpensive practice type amp which has an under powered amplifier and speaker - try your real bass amp setup.

If you have a tube front end (or power section) then it may be time to replace the tube(s).

If you are using a very large speaker with no midrange or tweeter then you will not get a lot of Treble response. In many causes you can turn the tweeter or midrange speaker volumes up on the speaker's crossover circuit.

A few pickups have very little treble signal in their response - they tend to be over-wound versions - if you have this type of pickup it will never get very bright but this is the trade-off in your pickup design.


Are these Built in the USA?

Depends on if you are in the camp of the lawyers from California who are suing manufacturers in the music industry for stating things are "Made in the USA" when any subpart is not made here.

News flash - by this definition NOTHING with electronics in it is Made in the USA - no fighter jets or other military items - no cars - none of it is Made in the USA.

We designed all the circuits which are unique and please see the link below to decide for yourself where it was made

Video of how we build our products in Oregon, USA.


Can you build a preamp with a different Tone Control Frequency Response?

Sorry - we do not make custom modifications to the designs.


Can I use the preamp with a power source from my amplifier?

It's possible assuming your have modified your amplifier or have one with an internal power supply to the ring of a stereo cable.

Rewire the output jack as follows - red goes to the ring connection where black is today - use a stereo cable from your bass to the amplifier.


I Lose Volume when the Balance is in the Center.

Your pickups are probably out of phase - invert the pickups hot and common wires to 1 and only 1 of the pickups.

Note if you have two neck or bridge pickups as opposed to a pair then you will probably have odd looking wire colors when the connections are correctly phased and they will not hum cancel if single coils when the balance is centered.


Why does the LED Flash when the Cord is Inserted into the Jack?

The flash tells you the batter level is good Video of how the Advanced LED Battery Meter works for a Pro JZ3 preamp which works the same as the Pro Z preamp.

If we left the LED on, as opposed to flashing it, then the power to drive the LED would drain your battery too quickly.


Why does the LED Flash seem to dim in the center?

This is how you tell the change in battery voltage level- it will dim down in the center over time to almost no light, at which point it will start flashing very quickly when the cable is inserted.

If this is the first time you have seen the fast flash you should make it through you gig but change the battery before your next gig.

Video of how the Advanced LED Battery Meter works for a Pro JZ3 preamp which works the same as the Pro Z preamp.


The LED seems to Flash Really Fast.

It is telling you the battery voltage is critically low and must be changed Video of how the Advanced LED Battery Meter works for a Pro JZ3 preamp which works the same as the Pro Z preamp.

If it does this with a new battery (and you are sure it was a good battery) then the pickup common wire is getting grounded. The electrical short must be found and removed. More info on Troubleshooting.


The LED is not Flashing any more when the Cord is Inserted into the Jack.

It is time to replace your battery, it is really dead .OR

In a few rare cases - the jack parts were touching conductive paint of foil in a cavity and keeping the preamp powered up which is also draining your battery - to fix, add an insulator in-between the jack parts and wall.


My Battery Died Overnight.

This normally means the cable was left in the jack - while the cable is in the jack ,the preamp is powered up - so remove the cable when you are done playing.

In a few rare cases - the jack parts were touching conductive paint of foil in a cavity and keeping it powered up - to fix add insulator in-between the jack parts and wall.


When I first insert the cord plug into the Jack it has a Loud POP.

Almost all preamps internal to a bass use a stereo jack to control the battery power.

The ring on the stereo jack touches the shaft of a mono plug which grounds the negative side of the battery and powers up the preamp.

While you were inserting the plug into the jack - the end of the cable hits the ring terminal which causes the loud pop.

Professional players get in the habit of pulling the other end of the cable slightly out of their amp jack when inserting the cable into the bass which stops the popping.


The Preamp is new and it never powered up when I Inserted the Cord.

We have tested the preamps 2 independent times before it is shipped - so let's look for simple issues to correct.

Most common is a bad battery, either it is very weak or completely dead.

Next is not getting the battery snap connected to the battery - make sure you have a good connection to both connections on the top of the battery.

Using a stereo line cord instead of a mono guitar cable - you must use a mono cord or the preamp will not power up.

Not inserting the cord far enough into the jack - the plug must go all the way into the connector.

Using a cord where the size of the plug shaft is too small to make a good electrical connection.


The Z-Mode Switch POPs loudly.

The Pots are SCRATCHY.

The Sound is Distorted.

The Preamp shuts down.

The Preamp eats batteries.

The LED Fast Flashes on a New Battery.

All of these problems have common wiring related causes and can usually be easily fixed.

Video of Troubleshooting Process



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Pro Z Preamp Series

Frequently Asked Questions