Marcus Miller Jazz Bass Wiring Problem

Discussion in 'Pickups & Electronics [BG]' started by MMFender, Apr 5, 2005.

  1. MMFender


    Sep 26, 2003

    I dont know how much difference these modifications make.
    Is it worth trying ?
    Any ANSWER would be great.
    here i paste :

    Hello. I'm Tommy.
    I'm glad I have had an opportunity to once again share my experiences about the Fender Marcus Miller bass with the players. The actual modifications and repairs I performed on my MM#1 bass are as follows:

    Modifcations - Before vs. Afterwards

    1) The battery died after only having the MM bass for 2 months. PROBLEM: The battery ground wire was connected to the back of the bass pot(common ground). CORRECTION #1: A)The battery ground wire was reconnected to the stereo output jack. (The active circuit was in "ON MODE" 24/7). CORRECTION #2: B)VERY IMPORTANT: Covered the "BARE WIRE(connected to the battery hot wire(RED))" coming out of the Fender FMEQ preamp to prevent the bare wire from "shorting out."

    2)The active/passive switch was "NOT" true-bypass. CORRECTION: A)Rewired the DPDT (on-on)mini toggle switch to "true-bypass."

    3)HELLLLLLLLLOOOOOOOO !!!!!!!!!!!!!
    VERY IMPORTANT: (For static pop prevention)- Remove the one(1)Meg resistor from the stereo output jack and resolder the one(1)Meg resistor to the "preamp input(yellow wire)/pole" of the DPDT mini toggle switch and to ground. (Once the 1 Meg resistor is removed from the stereo output jack, the stereo output jack should only have three(3) wires connected to it: hot wire, common ground wire and battery ground wire). The result of this gives true passive tone in passive mode.

    3)Disconnected the pickup and ground wires to the two(2)volume pots, and measured the resistance of both pots. Neck pot was 206 kohms & the bridge pot was 275 kohms. CORRECTION: Neck pot = 275 kohms, and Bridge pot= 206 kohms.(Currently these pots have been changed again to Neck Pot = 275 kohms, and Bridge Pot = 233 kohms).

    4) Disconnected the preamp and ground wires to the treble and bass controls. The resistance of the treble pot measured 467 kohms, and the resistance of the bass pot measured 437 kohms. CORRECTION: Treble pot = 437 kohms, and the Bridge pot = 467 kohms.

    As a result of these changes my Fender Marcus Miller bass performs the function it was intended to do; it supports the band. It has bigger bottom and more clarity. To me, this bass has a sound that is very similar to the "Marcus Miller Sound."

    Sound: N/A

    Sound: 10
    The "Marcus Miller Sound" - good bass/Whole lotta fingers

    Hello. I'm Tommy Thompson.
    The internet is incredible. Because of Harmony Central, I have been able to share my experiences about the Marcus Miller bass with players all over the world by email. Thanks again Harmony Central. :)

    Recently, I performed a comparison test of my two(2) Fender Marcus Miller Signature basses: The "Modified - Optimized Wiring vs. Original Wiring"

    The KEY to the Marcus Miller sound - BALANCE.

    IMPORTANT NOTE - If you use the TRUE BYPASS - active/passive switch, remove the 1 Meg resistor from the output jack and resolder the 1 Meg resistor to the "preamp input(yellow wire/pole)" to ground.

    The modified Marcus Miller bass sounds very much improved. The output is more, the passive mode is definitely passive and the bass sounds much better when each pickup is played individually. "The side effect is that both basses sound more like Marcus' real 1977 Fender jazz."

    The only thing that was done, was to "rearrange the volume pots."

    The KEY to the Marcus Miller sound is - BALANCE. Ideally, both pots should be 250 kohms, but practically, that's not the case.

    Hence, the volume of the neck pickup is most important for a Fender jazz bass. Therefore, the neck pickup volume pot should have more or same resistance if possible. For example, if you have two volume pots; 230 kohms & 270 kohms. In my opinion, the 270 kohms should be connected to the neck volume pot, and the 230 kohms pot should be connected to the bridge volume pot.

    Why is this important? This is important because, the pickup closest to the neck produces more bottom and should support the band. Therefore, this is the pickup that should be emphasized because it gives your bass its warmth and roundness. The bridge pickup should provide flavor.
    If anyone, understands the PROBLEM/DISCREPANCY I am having please email me.
    Sound: 10
    I reported in my earlier reviews that my jazz basses sounded like Marcus Miller when the order of the volume pots were re-arranged. This is also mentioned on my reviews for Lindy Fralin, John Suhr and possibly a few other Jazz Bass pickups. I was "THEORETICALLY WRONG."
    "DISCREPANCY: Between theoretical(wiring diagram - circuit) and experimental sound of the Fender Jazz bass."
    1) The jazz bass circuit has two keys points: a) When both volume pots are at zero(0), and b) When both volume pots are at ten(10). At those two key points all points are basically the same. In other words, it doesn't matter if the stronger pot is in the neck or the weaker pot is in the neck position. At "10" both pots are in parallel, so it doesn't matter because everything comes out the same.
    2) When used individually the value of the pots do matter. In this case, having a larger neck pot does produce a louder and brighter sound. The same is true if the larger pot is connected to the bridge pickup. A larger pot in the bridge position will produce a louder and brighter sound.
    3)Choose wisely. I like to have a neck pot with more resistance and a bridge pot with less resistance. For example, neck pot(275 kohms) and bridge pot(234 kohms).

    Sound: 10
    Problem #1-Battery Failure.
    Use the current stereo output jack to complete this modification. Please do not remove the 1 Meg resistor, it quiets the "popping sound" when the active/passive switch is engaged.

    To correct the battery failure problem go to the following 2 websites:

    Tip - "hot" connection, Ring - "battery ground" connection, and Sleeve - "common ground" connection. Go to "Wiring Diagram #1" to see an illustration.

    Problem #2-Active/passive switch.
    NOTE: The active/passive switch currectly on the Fender - Marcus Miller jazz bass goes through the preamp. I hear EQing on the sound, but passive tone should have no EQing. I wanted my MM bass to sound like my original 1975 and 1978, so I rewired the active/passive switch.
    To understand how a TRUE "Active/Passive" switch is installed look at the two(2) following websites:

    In the Bartolini old tbt diagram, the "yellow wire" is the preamp input wire. The "green wire" is the preamp output wire. On the Fender - Marcus Miller bass, the "yellow wire" is the preamp input wire, and the "white wire" is the preamp output wire.
    One(1)additional piece of wire is needed to complete this modification. One piece of 22 awg insulated wire 2 inches long. Cut to desired length to make connection for the two north poles(toward headstock) of the active/passive switch. Rearrange all other connection wires to there new points of destination as indicated from the website drawings. The current lengths of these wires should be long enough to work.
    Action, Fit, & Finish: 9
    Same as before.
    Reliability/Durability: 9
    Same as before. Everything does what it should.
    Customer Support: N/A
    Overall Rating: 9
    I believe it is important to understand basses with active electronics. I personally have a Fender-Marcus Miller jazz bass wiring diagram that shows the battery connection wired correctly. So I would say that Fender has showed their workers what should be done. I know that the "TONE" of this Marcus Miller bass competes with any bass(Music Man, Pedulla, Mike Lull, Sadowsky, Alembic, and etc.) I have seen. The output of the preamp isn't as loud, but it was designed that way because that's the way Marcus's bass really is. Bass players need not fear the new modern type sophisticated bass instruments and their electronics. These bass instruments with TRUE "active/passive" electronics can fulfill the best sounds of the past and the future

    I have 2 Marcus Miller Jazz basses. Recently I discovered a way to "improve the sound of my basses." I changed the wiring on my active/passive switch so that it truly acts as a real "ACTIVE / PASSIVE" switch.
    Rewired Switch: COMMENTS: Use the same DPDT mini-toggle switch; use the same 1 Meg resistor on the output jack; and NORTH direction is toward the headstock and SOUTH is toward the end of the body....... 1) Disconnect all of the wires on the mini-toggle switch; 2)On the (2)NORTH poles "connect an insulated wire from one side to the other"; 3)On the middle right(EAST)side connect the "output from the pickups"(white wire) ; 4)On the bottom right(EAST) side connect the preamp input(yellow wire); 5)Connect one end of a wire to the middle left(WEST) side and the other end to the "hot spot" on the stereo jack; 6)On the bottom left(WEST)side connect the preamp output(white wire). Do not disconnect the resistor on the output jack. It buffers the noise(pop) when the active switch is engaged.
    I believe what Fender did is cool, given the fact that they are an assembly line type production, and you and I know that time is money.
    The sound of the true instrument comes alive once the switch is changed. "Tell me what you think."
    I think my MM's black knobs dont work as EQ.
    they work more like a pick up volumes.
    i still dont get if my bass has a problem or not.
    i bought it from THE BASS GALLERY in Camden - London in 2003. The bass player from Incognito - Randy Hope Taylor
    was selling it.
    Martin at the gallery said he fixed the problem.
    i am so confused now...
    i have e-mailed Martin.I am waiting for more information.
    i hope i will really find a solution to this.

    Would i ruin my bass if i change the whole electronics of the bass ? Pick ups etc...So that i can have a louder bass with more tone options.And the passive mode would be louder and rounder maybe...what set up do u suggest
  2. Snerek


    Jan 12, 2007
    I recently have been experiencing issues with the wiring on my bass, if you could please read my email and either make some suggestions or refer me to someone else that can help, I would greatly appreciate it!

    I just got off the phone with fender support regarding 2 wires that came loose on my preamp system while in a recording about bad timing!

    My bass stopped working and when I got home, I took the preamp section apart to look and see what was wrong.
    1st - The White wire in the middle of the ACTIVE/PASSIVE switch came undone. I reconnected it to the input section.

    Now, the bass works, but there is still 1 wire that is not connected, it's black, appears to be a ground wire and is soldered to the Treble dial.

    I have looked on the wire diagrams and none of them show more 1 ground coming off that Treble dial, my bass has 4 black wires at 2 solder points on that Treble dial! One of those black wires is not connected anywhere, can you please help me find out where this wire connects to.

    Please see my photos attached and let me know if you have any advice please. I can be reached at
  3. rfowler62


    Jul 4, 2005
    I have a new Marcus Miller 4 string which was very noisy.
    I completed the TOMMY THOMPSON WIRING MODIFICATION wiring upgrade as directed and it sounded amazing.
    It sat unplugged for a few days and when I went to play it today the active side is dead. I tried to re-wire it the way it was but nothing.
    Could I have fried the pre amp? Any ideas?
    If I need a new pre amp where would I get an original replacement? Been looking all over the net but can't find it.
    The pre amp is a Fender FMEQ 080097