Jazz Plate Preamps

Pro JZx

Module Preamps

Fender American Deluxe Jazz Bass Pickup

Mods when used with a Z-Mode Preamp

When are these mods needed?

These mods only apply if ALL of the following are true:

  1) Your Audere preamp is a Pro JZx preamp. This mod is not required with the New Audere Jazz Preamps.

  2) Your bass has Fender American Deluxe Jazz stock pickups.

  3) The pickups have the pole pieces grounded.


Can I tell by looking at the pickups whether they need the mod?

If your pickup covers are the originals you can look at the covers

  1) A cover with no writing on it is usually a Shur pickup which does not require a mod

  2) A cover with Noiseless written in Gold script is Fender's 1998-2005 design and is being returned to in 2015 - this pickup does not require a mod


  3) A cover with SCN stamped into it from 2005 to 2009 requires a mod - see how further down the web page.


  4) A cover with N3 in silver letters on it from 2010 to 2015 requires a mod - see how further down the page


  5) A cover with 2 areas in silver letters on each side of the pickup from 2016 to 2024+ requires a mod - see how further down the page



Can I do a simple test to see if I need to make a mod?

1) Turn your amp down to a low volume.

2) Slowly push the string into the pole piece.

3) If you hear a low volume pop that's normal - the magnets will suck the string into the pole pieces when the string gets close - so no mod is needed

4) If you hear a really loud pop then you probably need to modify the pickups.


Why are Mods need?

Mods are need with some versions of the stock pickups to separate the pole piece ground from the pickup common wire.

If your pickups require the mod and it is not made when the string hits the pole piece then it will pop extremely loudly.

This condition is fixed by separating the pickup common from the pole piece ground so now the pole pieces are grounded just like the strings.


Why did Fender connect the pole pieces to ground?

Well we kind of did this one to ourselves - back in 2003 we published an Application note which showed the advantages of grounding pickup pole pieces. If the pole pieces are ungrounded, like on a traditional jazz pickup, and your finger touches a pole piece and the string at the same time then your bass will hum. And if you happen to have a static charge on your body the bass output will pop loudly. This is totally independent of any preamp - it happens with a passive jazz. We just exposed the issue.

What we demonstrated in the application note, which was news at the time, was that if you take a conductive adhesive foil strip and adhere it to the back side of the pole pieces and ground the coper foil with a new wire to ground then the hum and popping will be reduced greatly to an insignificant level.

Today several pickup makers ground the pole pieces - Fender did this with a circuit board on the bottom of the pickups which is a good technique. Most pickup manufacturers like Aguilar, Nordstrand and even Fender on other pickups understood the benefits of keeping the pole piece ground separated from the pickup coil so a 3rd wire was added.

For the stock pickups in the American Deluxe Jazz Basses Fender only used 2 wires and this creates a problem for our Z-Mode preamps so this web page explains how to take your 2 wire pickup and create a 3 wire version.


Can the mod be Reversed?

Yes this is really easy - we are electrically separating 2 parts of the pickups for most of these mods.

In the unlikely event that you want to reverse the mod the simplest way is to take the 2 wires and connect them to the same place the one wire would have gone.

In this case the 2 wires will always be going to ground with a passive bass or other preamps.

You could also unsolder the extra wire and use a small jumper on the bottom of the pickup if you prefer to reverse the mod this way.


Will the mod change the sound of my pickups?

No for the SCN, N4 (Elite) or Ultra pickups which are the most commonly modified versions.

Yes/No for the N3 pickups - the mod I recommend makes them sound much closer to Fenders standard single coil pickups but without the noise which is how they are sold by Fender. I also explain how to mod them to work with the original Notched Filter response if you like that sound.


How to mod "SCN" (Samarium Cobalt Noiseless) pickups?


Under the pickup covers they look like this:


The SCN pickups need to be modified by making a small wiring change on the bottom of the pickup - you cut 1 wire jumper and add a new wire to ground.

This change will not effect the sound and is always a good mod - it is electrically separating the pickup pole piece ground from the pickup common.

Below is the location of the wire jumper to be removed (just cut out the existing wire with nippers) which is connecting the triangle to the square pad.

FYI - The triangle shaped pad is the pickup common. The square pad is the pole piece ground. The round pad is the pick hot connection.


After you cut out the wire jump - you add a new wire from the square pad which will go to the electrical ground off the center pin of the jack as show in the picture below.

You can use any convenient sized and type of wire to make this electrical connection.


This completes the mod.


How to mod N3 pickups?


Under the covers they look like this:


N3 pickups need to be modified to work with a Z-Mode preamp but IMO the best mod will clearly change the sound of the pickup.

My recommended mod will remove a Notch Filter response from the pickups mid range. Removing the notch filter will make it sound much closer to a traditional Fender single coil pickup.

This mod has not been used by too many of our customers because most of them have long ago replaced the stock N3 pickups with after market versions in order to get a more traditional sounding pickup.

Looking at the picture below - Fender this time connected the pickup pole piece ground which is still a square pad as it was on the SCN to the pickup common pad (where the green wire goes) with a large trace on the printed circuit board. Normally I would have cut the trace between the pickup common and used the square pad by putting a wire into the square pad's hole but in this case it was not possible due to plastic on the top side of this board that I did not want to melt.

The mod procedure is:

1) The Square pad is connected to the copper flooded board area which grounds the pole pieces by a thinner trace. The plan is to break the electrical circuit at that point. If you look carefully at the board below between the square pad and the flooded plain you will see I have severed the tracking by taking an Xacto knife and completely cutting through the metal trace. Make this cut slowly in multiple passes and take your time -  you must completely remove a strip of the copper but not go too deep - it is not hard, the board is at least 20 times thicker than the copper so just take reasonable care.

2) Optionally, if you have a DMM test the resistance between the green wire and the back side of one of the pole pieces - your meter should read infinite resistance or no connection after the cut.

3) I recommend you stop and skip to step 9 - the pole pieces will hum if you touch them but the notch filter response has been removed so the pickups sound more like traditional jazz pickups.

4) If you want the Notch Filter response then proceed with step 5

5) A spot on the solder mask over the copper is selected (you can select any spot) for mechanical removal. You can use the Xacto knife tip to scratch off the solder mask. The color of the spot will change from Red to a Silver color as the mask is removed. You only need to remove a very small area where a wire will be soldered to the copper plain.

6) Pre-Tin the area where the solder mask was removed to make it easier to solder on your wire.

7) Solder on a new wire - the other end of this wire will be connected to the common ground wire (Grey/White) which comes off the center pin of the output jack and also grounds all other shielding in the bass.

8) Optionally, with the DMM test the resistance from the other end of your new wire to the back of the pole pieces - the meter should read < 1 ohms of resistance.

9) Put some insulator into the cut area - lacquer (nail polish) works well at these voltages.



This completes the mod.


How to mod N4 (Elite) pickups or Ultra pickups?


Under the covers they look like this:


N4 (Elite) pickups are Orange on the bottom


Ultra pickups are Blue on the bottom



N4 and Ultra pickups are very similar in sound and construction. The Ultra pickup set has a larger difference in the Neck verses Bridge turns ratio.


For the N4 and Ultra pickups, Fender connected the pickup common wire to the pole pieces on the bottom of the pickup PCB, same as on the N3 pickup. What is new, Fender also added a 2nd reversed image to the top side of the PCB. Cutting the problematic connection on the bottom of the PCB is easy but to cut the top side is not. That's because the top cut location is under the lower plastic winding coil bobbin - it is possible to make this cut after trimming back the plastic bobbin but it is very difficult. So I recommend taking a different approach to solving the problem.

The good news is the stock N4 and Ultra pickups both sound much nicer than the stock N3 pickups.


Three options for working with N4 and Ultra pickups:

1) The simplest and lowest cost solution is to install after market, solid top, plastic pickup covers for Fender Jazz pickups - add this insulator and you are done

2) Replace the Fender pickups with a Nordstrand or Aguilar hum canceling pickups which sound better to most players.
The Nordstrand and Aguilar have taller side by side sub coils and sound closer to a traditional alnico single coil pickup - aka that sound Fender made famous.
The Fender pickups use a short stacked over/under coil design which has equal noise cancellation in a 4 string bass and better noise cancellation in a 5 string bass.
In the end, the Nordstrand and Aguilar pickup replacement verses the Fender pickups trade-offs include:
   4 string - better sound verses more money
   5 string - better sound verses more money and less noise rejection.

3) Coat the Fender pickup's pole piece tops with a clear tough insulator so your pickups look stock.

     I recommend creating a clear epoxy insulating layer as follows:

  1.     Collect your supplies
    1.     99% Isopropyl Alcohol and Q-Tips to clean off the wax on the pickup - wax will clean off much faster with 99% Alcohol and it will not melt plastic like a more aggressive solvent.
    2.     Select a clear, self leveling, bubble free epoxy with a reasonable open time - I used Janchun Premium Crystal Clear Epoxy in a 16 oz set from Amazon
    3.     A small disposable plastic cup to mix the epoxy parts A & B together
    4.     Multiple pairs of lab gloves - nitrile powder free gloves are a good option
    5.     A weighing scale with a resolution of 0.01 grams
    6.     Plastic stir sticks to mix the epoxy - wood can shed fiber debris and color the mix
    7.     A low temperature heat source to help clear bubbles and thin the mixed epoxy
    8.     A small paint brush - toward the stiffer side
    9.     Small foam swabs to remove excess epoxy
    10.     An X-Acto knife with a new blade
    11.     Two 3ml syringes with small blunt plastic needles - the needles help reach into the epoxy bottles and allows 0.01 to 0.02 grams per drop to be put into the mixing cup
    12.     A timer - nothing special
  2.     Start warming the epoxy bottles to 105 degrees F to make mixing easier
  3.     Remove the cover from the pickup being careful to not catch the winding wire which is small and very fragile - note you can use the pickup's magnets to help hold the body of the pickup coil in place
  4.     Clean both the top and bottom sides of the pickup; the wax will get on your hands and if any wax is on the top of the pickup pole pieces the epoxy won't stick
  5.     Glove up
  6.     Extract 1.5 cc of part A epoxy into the 1st syringe and extract 1.5 cc of part B in the 2nd syringe
  7.     Tare the mixing container on the scale
  8.     Deposit 1 cc of part A into the mixing container, record the weight, multiply by 0.89 and record this weight for part B - for many other brands of 1:1 epoxies you use the same weight for each part
  9.     Tare the mixing container on the scale
  10.     Deposit part B from its syringe matching the part B recorded weight - most epoxy has a range of +/- 10% off the 1:1 volume ratio but I find epoxy works better limited to +/- 2%, so always use a scale
  11.     Mix the epoxy for 4 minutes with a plastic stir stick - mix slowly and thoroughly, scraping the bottom and sides of the container. Most sources will tell you not to mix less than 2 oz (63 grams) of epoxy or it may not setup - I prepared 2.1 grams of epoxy without issues by using precise epoxy mixing techniques
  12.     Set the epoxy aside for 4 minutes to let some of the air bubbles created during mixing clear
  13.     Slowly mix the epoxy for 2 additional minutes using the paint brush including all around the bottom of the mixing cup
  14.     Paint the top of the pickup pole pieces and around the pole pieces with the brush - not very thick - I applied about 5% of the epoxy I made up
  15.     Use foam swabs to remove any extra epoxy especially between the 2 pole pieces of each string path
  16.     If you find the epoxy is not sticking to the top of one of the pole pieces -  probably it has wax on it from handling - scrap off the epoxy and wax with the X-Acto blade and reapply epoxy with the brush
  17.     Heat up the pickup (be gentle to not melt any potting wax etc.) to help clear any air bubbles - the sharp tip of the X-Acto knife can be used to pop stubborn bubbles
  18.     Leave the pickup in a level position and do not disturb it for 24 hours to allow the epoxy to cure
  19.     Test that the epoxy has hardened on the top bobbin where it will not be visible after the cover is installed - complete epoxy hardening is relative to the application; epoxy takes months to fully cross-link

    OK that was long and detailed but hopefully you get the idea - you are just putting an epoxy insulator over the top of the pole pieces.


    Ideally the pickup pole pieces would be very slightly subset under the case top to reduce the risk of the strings scrapping off the epoxy coating.

    You can also move the pole pieces down with an insulator (thin plastic etc.) attached to the top of the pickup coil if needed.


This completes the mod.



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Fender American Deluxe Jazz

Bass Pickup Mods

when used with a Z-Mode Preamp