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How hard is it to make my Jazz Deluxe 18v pre passive?

Discussion in 'Pickups & Electronics [BG]' started by Aaron_D, May 20, 2011.


  1. Aaron_D

    Aaron_D

    May 9, 2010
    Tallahassee, FL
    I have an 06 Fender Jazz Deluxe with SCN pickups and the 18v fender pre. Obvioulsy without batteries nothing works. How hard is it to make it passive?
     
  2. Aaron_D

    Aaron_D

    May 9, 2010
    Tallahassee, FL
    Ill take the silence as "hard".
     
  3. faulknersj

    faulknersj Supporting Member

    Apr 4, 2008
    Scottsdale Az
    I think you have a couple of options. You could remove the preamp and current control plate entirely and install 2 volume knobs (1 for each pickup) and a passive tone control knib very easily and inexpensively. The other option is to buy a control plate (like a J Retro) that has both a preamp and a passive/active toggle switch so that you can enjoy the best of both worlds. This way you have passive when u want it and active when you want it.
     
  4. MikeBC

    MikeBC

    Oct 28, 2009
    Keep wailing on it until it submits. Sorry, couldn't resist.

    I vote for the 2nd option offered by faulknersj,
     
  5. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    the third option is to rig up a bypass switch to disconnect the preamp you have, turning the bass passive. (maybe the volume can become a push-pull, or a mini-toggle can be added somewhere.)

    i wouldn't recommend it though, as that preamp adds some brightness to those otherwise "polite"-sounding stack pickups. bypass it and you'll have a duller-sounding bass.
     
  6. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    How the question, do you want to make it passive to change the tone, or are you afraid of dead batteries?

    I've said this a bunch of time, but I've been using active basses since 1977, and never once had a battery go dead on me. If you are the worrying type, just check your battery every week or so, and change them when you change your strings, unless you don't change your strings.

    Something like this makes it painless to check the battery.

    STEWMAC.COM : Batt-O-Meter

    I just use a multi meter.

    Oh and your amp doesn't make any sound if you unplug it either. ;)
     
  7. Phendyr_Loon

    Phendyr_Loon

    Sep 4, 2010
    I've experienced this. I own a Jazz with a Aguilar OPB-2 and SCN pickups. The volume is a push-pull wired for active/passive. Those pickups on passive sound dark and bland. I suppose that's why Fender put a preamp in every SCN equipped bass.
     
  8. Aaron_D

    Aaron_D

    May 9, 2010
    Tallahassee, FL
    I just got an outboard Sadowsky preamp. It sounds so great with my passive basses, but Im getting hum from my deluxe...the two preamps arent playing nicely.
     
  9. bassbenj

    bassbenj

    Aug 11, 2009
    The answer as you surmised is "hard". The problem is the Fender Pre has an oddball volume control. Thus replacing the volume pot and adding a passive bypass is not a simple operation.

    It has been done, however. There is a thread somewhere here on TB where someone did this operation. Basically the old volume control was removed from the preamp and placed inside the cavity permanently full "on" with a second more normal volume control to act as the the new volume. The standard wiring then allows the installation of a bypass switch. All in all it's a pretty complex operation which is why I haven't done it to mine yet. But the good news is that with some effort the change IS possible!
     
  10. lowendgenerator

    lowendgenerator

    Mar 26, 2006
    CHI/NWI
    Reviving this thread, because I'm looking for the thread that bassbenj is referring to. I've got 2 Deluxe Jazz basses, and I'd like the option to run them passive when using outboard preamps.
     
  11. Stranger Danger

    Stranger Danger Feel Like A Stranger Supporting Member

    Jan 3, 2010
    Texas
    Zombie bump. Anybody got a clear answer on this one?
     
  12. I had a Jazz Bass Deluxe and being more a fan of passive Jazz Basses I got it wired Volume Volume Tone by my tech guy (so to answer your question it was super easy. I paid something like $80 and never looked back.
     
  13. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    Fender does. In order to wire it up as Fender does you would need to replace the volume pot on the preamp board with a dual "Reggie Hamilton" volume pot that you can get from several bass/guitar parts places. Soldering a new pot into the preamp board is not exceedingly difficult but it is not for the faint hearted. Once you have the new volume pot in place you just need to add a toggle switch and follow the fender wiring diagram.

    Ken
     
  14. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    yeah, but remember, the older varieties of noiseless fender pickups aren't so spectacular in passive mode.

    it could end up being a bunch of work for a tone setting you discover you don't much like.
     
  15. Correct about the noiseless pickups, after I turned mine to passive I replaced the pickups by Lindy Frailins.
     
  16. Stranger Danger

    Stranger Danger Feel Like A Stranger Supporting Member

    Jan 3, 2010
    Texas
    Thanks, it's not so much tone that I'm after just an emergency "parachute".
     
  17. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    Pickups are a whole other can o' worms. If you want a passive switch, put in a passive switch. If you then don't like the pickups, change them. Everyone else does! I suppose the Reggie Hamilton does have the advantage that it comes standard with a pretty decent P bass pickup that you can use in passive mode.

    If all you want is a parachute then I would probably not bother with trying to replace the volume control and that would simplify the mod to the point that someone other than a dedicated electronics hobbyist could deal with it comfortably. I'd just pull the signal off the blend pot as Fender does and feed it through the switch and then to the output jack without a volume control. In an emergency you can use the volume control on the amp, or a volume pedal.

    Ken
     
  18. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    I've been using active basses since about 1977, and never once had a battery go dead or anything else that required being able to switch into passive. I have broken strings, and had other things break, but never had a battery go dead during a gig.

    There's really no reason to worry as long as you check your batteries every so often. If you change your strings on a regular basis, check the batteries then.
     
  19. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    If you would be happy with a parachute that worked on only one pickup you could use half of the blend pot as a volume control in passive mode. If you look at detail A on that Reggie Hamilton diagram you see the blend pot. On a normal active Jazz the wire labeled as going to the passive switch goes to the preamp input and you would have to cut that wire and route the blend pot side to the middle left terminal of the passive switch in detail C. Then you would route the preamp side of that wire (let's call this blend pot wire 1) to the lower left terminal of the same switch. Looking at detail A again you see a wire connecting the lower left terminal of the blend pot to the upper right terminal of the blend pot. Cut that wire and run a new wire (let's call this blend pot wire 2) from the lower left terminal to the lower left terminal of the passive switch, which is the same terminal the preamp input wire connects to. Note that depending on which pickup you would like to use in passive mode you may have to swap the connections of blend pot wires 1 and 2. Now you have to find the wire from the output of the preamp to the output jack and cut that wire. Route its preamp side to the bottom right terminal of the passive switch and route its output jack side to the middle right terminal of the passive switch (the wire labeled only as 6" white wire in detail C of the Fender diagram goes to the output jack). Now you run a shorting wire from the top right terminal of the passive switch to the top left terminal of the passive switch, ignoring the instructions about the volume pot connections.

    With these connections everything works per normal in active mode. In passive mode only one pickup will be routed to the output but the blend pot will act as a volume control for it.

    Ken
     
  20. Stranger Danger

    Stranger Danger Feel Like A Stranger Supporting Member

    Jan 3, 2010
    Texas
    I'm sure you're right and you obviously have a lot more experience than me. (I was potty training in 1977 and I'm pretty good at that now.)

    So I'm going to follow your advice and leave it alone. I just wish they made a batt o meter that worked with 18v preamps.

    Thanks for all the tips guys.
     

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