Jazz Plate Preamps

Pro JZx

Module Preamps

Pro JZx Preamp Series - Frequently Asked Questions

I have a Jazz  Preamp - how is this Pro JZ3, Pro JZ3D, or Pro JZ6D Preamp different?

We are happy that you have one of our jazz preamps, we appreciate that we have a lot of repeat customers...

The Pro preamps include the Z-Mode system -  when the Pro Z-mode switch is in the center position, it's in the Mid Z-Mode setting and sounds just like your non-Pro Jazz preamp. This setting sounds like a passive bass. The Pro JZ preamp has 2 additional settings which extend the range of sounds produced by the pickups.

The Z-Mode system includes our traditional Low, Mid and High Z-Mode settings which are preprogrammed and each switch position can be reprogrammed, at your option, for different Z-Mode combinations.

In addition to volume and balance mixing, we offer dual volume pickup mixing.

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

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

The LED meter is more advanced with multiple flash sequences to give you more information about the batteries charge.

Active pickups are not recommend with this preamp. Due to their internal electronics you will lose the Z-Mode feature.

The pickup input connector contains 4 slots, and the pickup commons are not grounded, instead they are connected to the preamp connector.

There are replaceable caps, one for each pickup, which change the frequency peak location.

Individual pickup gain adjustments are present to match the Low Z-Mode response to the Mid and High Z-Mode level.

To sum it up, this is a more advanced preamp with a different feature set trade-off vs. price point.


How does the Advanced LED Battery Meter work?

Video of how the Advanced LED Battery Meter works


Will this much performance really fit into a Jazz Bass Electronic Cavity?

The preamp easily fits into a standard Fender Jazz cavity and most jazz bass makers use the same cutout.

To demonstrate the fit - we hand built a Control Plate from Clear Lexan so you can see there is plenty of space remaining after the preamp is installed.



Can I Install the Preamp myself?

Probably, most are installed by players - see the Installation Animation or the Instruction PDF

It will be harder to install into a bass with a side mounted jack where a hole is drilled between the electronics cavity and the jack cavity. If a hole is used (as opposed to a slot) then the output jack wires must be desoldered from the jack - the wires fed though the hole - then re-soldered to the jack leads.

For most side mounted jack bodies your bass will have a battery box;  un-solder and remove the battery clip, then solder the wires to the red (+) and black (-) connections on your battery box.


Can you recommend a repair shop or luthier to install it?

Unless you have special needs I would recommend that you consider installing it yourself - it is normally that easy.

If you want to add a backside battery box (almost never required) then most players should take it to a luthier or technician.

If you want to add a side jack then having the correct jig makes it a much simpler modification.

If your bass is in the repair shop for another reason then they should be able to install it for your quickly and easily.


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 from PayPal when we ship than contains the tracking number.


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.


Will it work in my Fender Jazz Bass?

It works in all common jazz basses - US, Mexican, Squier, Highway One, Geddy, Japan models etc...

It is notable that the Aerodyne is problematic with a very thin body and slightly curved top so we don't recommend putting one into it.

It will not fit some of the Jaguar basses with the small curved plate.


Will it work with my Fender --- Pickups?

It will work with all Fender and Squier single coil pickups. These are by far the most common pickups that Fender has sold.


If you have an American Deluxe Bass with Fender hum canceling pickups then some simple mods might be needed. At least each of these pickups types with potential issues can be identified looking at the top of the pickup.

Note - Standard (Mexican) Deluxe jazz basses with stock pickups have no issues.

For the American Deluxe Jazz Basses there has been 6 types of pickups.

The oldest versions had no writing on the pickups and do not need any modification.

The Noiseless pickups (maybe called Original or Vintage Noiseless in Fender's literature) were the first vertically stacked noiseless pickups and will most often work without any mods; these are the best of the vertical stacked hum canceling coils. The writing on these pickups can be hard to understand due to the script and the script was not recessed into the plastic so was subject to wear.



The SCN pickups will work after making a small wiring modification on the bottom of the pickup - the mod separates the pickup common from the pole piece ground and will not change the sound of the pickups.

More information



The N3 pickups will work after making a more major modification. The modification will change the sound of the pickup or not - stock it has a large notch in the frequency response - after the mod it will sound much more like a traditional single coil pickup which is the sound which made Fenders famous. If you have these pickups and like them, they will work with our lower cost Jazz series of preamps unmodified.

More information



The N4 (Elite) or Ultra pickups will work after making a modification. The modification will not change the sound of the pickup which is much nicer than the N3 unmodified.

To identify these types of pickups look at both the left and right sides of the pickups for markings as shown below.

More information



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 had 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...


What Jazz pickups sound best?

The answer to this question depends a lot on what type of music you play and how you approach it.

That said - Nordstrand tends to be a customer favorite- their pickups tend to be unique compared to other makers and their noise canceling versions sound very close to their single coil pickups.


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.


What is a Good but Low Cost Jazz pickup to replace my really cheap ones?

Look for a pair of Squier Vintage Modified Jazz bass pickups (new or used) - both the Duncan Designed versions and the Fender Designed versions are good AlNiCo single coil pickups.

The Duncan Designed versions are slightly more vintage sounding but both are really nice and sound amazing for the price.


What is a Good but Low Cost Hum Canceling Jazz pickup?

I will assume you mean for a 4 string - look for a pair of Fender Super 55 pickups (which are not made anymore) - they can be cheap and are really good - much better IMO than some of Fender's other hum canceling jazz pickups due to their side by side coil arrangement instead of the vertical coil arrangement that Fender used on the Jazz hum canceling bass pickups.


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.

For Fender pickups White (and/or Yellow) is normally considered hot and Black is common.


How do I know which pickup wires are the Neck vs Bridge?

The Bridge pickup wires most often come through a hole which is located closer toward the Bridge end of the cavity.


If you are upgrading a passive jazz bass then the center lug of the 1st pot (closest to the neck) is the Neck pickup hot wire - look at the --> point.

The Bridge pickup hot wire goes to the center lug on the 2nd pot.

The other wires soldered to the back of pots are pickup commons or grounds.



If you have an older American Jazz with an S1 switch then the Neck hot is still soldered to the center lug of the 1st (Neck Vol) pot - click to expand the picture below and look at the --> point.

The Bridge pickup hot is a white wire soldered to the bottom of the switch board.

You may notice that the Neck pickup's common (a black wire) is also soldered to the bottom of the switch board while the Bridge common is soldered to the back of one of the pots all of which will be grounded.



The Pickup Input Connector has 4 Slots?

All pickups still have a pickup hot and pickup common connection; for this series of preamps; the pickup commons must be connected to the connector 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 connector.

Normally you hook the pickups black to the input connector as common and the white (or yellow) to the hot input.



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.

Install the White (or yellow) Hot in the input connector.

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 insert it into the input connector.

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.


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 together with the Grey/white wire off the jack.

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


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, 3 for a JZ3 preamp or 6 for a JZ6 preamp different pickups.

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.

The JZ6 preamps has by default these same 3 settings but adds 3 more - a darker neck with a typical bridge, a darker neck with a brighter bridge, and a typical neck with a brighter bridge.


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 Jazz Pickup response in each mode?

The following curves were generated with a Fender single coil AlNiCo Jazz pickup but almost all traditional sounding jazz 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 Jazz 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, the manufacturer, 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 our out Jazz Preamp Series which are lower priced.


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

The following adjustments are all optional - we have preset them for Traditional Jazz Bass Pickups.

This FAQ 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 separate programming switch, it goes on the 2 Pin Connector on the right side of the lower part of the Preamp 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.


Optionally Install the Red Button Switch which is an optional Accessory onto the 2 programming pins. You can install the switch either direction on the Pins.



You can make the adjustment process easier by feeding the switch wires out from under the Jazz Control Plate with the Preamp lightly screwed down, do not crush the wires.



OR If you do not have a programming switch then instead of pushing down on the switch button you can use a metal object (screw driver blade or paper clip etc.) to short between the 2 pins briefly - this is what pushing in the switch does.


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.

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.


After you are doing with programming the switch settings, disconnect the Red switch and store it in case you want to make future changes.


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.


Will the Preamp fit in my Jazz Bass?

Probably - almost all Jazz basses have a similar electronics cavity size.

The cavity must be 1.0+" wide (required to fit a 9 volt battery in), 1.2+" deep and 4.8+" long.

Fender's standard is 1.19" wide, 1.27" deep and 5.17" long which most non-Fender basses copy.

If you are worried - see if the battery will fit into the bridge end of the electronics cavity laying on its wide side - this is the most common limiting point.

Please see the next question.


Will the Plate fit with my Screw Holes?

Almost all jazz control plates are the similar - based on Fender's plates.

Exceptions include some basses with clearly curved control plates like a Lakland DJ bass.

Please see the next question.


Will the Plate match my Pickguard?

The plate was designed to match the curved radius of the American, Standard (Mexican) Jazz basses and the Squier Vintage Modified basses.

Some of the Squier basses and other low cost basses used a slightly more squared off plate at the top to save money during construction.

The gap on these basses can be a bit larger in the center and while you can see a small gap, most players don't notice it after installation.

If you want a "perfect" fit for one of the squared off pickguards then I suggest you replace the pickguard with an upgraded part.


Will it work with a back side routed bass cavity?

If your bass uses a control plate on top for the traditional look then it will work fine.


Will it work in a Wood Top with No Plate?

Maybe but only if the holes are exactly in a line with the traditional Fender control plate hole spacing, and you may have to increase the size of the holes.

The single controls need a 7 mm hole - the stacks need a 9 mm hole.

If you want to use the LED battery meter, it requires a 1/8th" (3.15 mm) hole.


Can I get it with a different color of knob set?

We offer Chrome, Black, and Gold.

There is a slight extra cost for non-Chrome knobs.


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.


Does it come with a Black or Gold Control Plate?

No - we tried these in the past and the quality of the plates did not meet our expectations.


Can I change the Control Plate?

Maybe - if the plate you purchase has the holes in the standard location and they are big enough then you can unscrew the parts and move them over to your plate.

Your new plate will probably not have a hole for the LED battery meter - either lose the feature by moving the LED back or see the next question.


I need to add a hole for the LED Battery Meter to my own Control Plate?

The hole size should be 1/8" or 3.1 mm.


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 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 under the preamp circuit board.


Can I hook it up to my Battery Box?

Yes -

If your version of the preamp has the jack mounted on the plate then cut the battery end of the jack off.

For a preamp with a side mounted jack - 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?

Not possible 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 explain 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.

A few Fender Jazz versions (SCN and N3) need some modifications to separate the pickup common from ground. More info


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

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


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

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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  Audere Audio

  4909 S Coast Hwy, STE 295

  South Beach, OR. 97366

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