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Passive Jazz distorting troubleshoot

DylanD

DylanD

Feb 10, 2011
52
21
Tucson, AZ
#1
background:

I bought a used fretless Lakland 44-60 that had a J-retro preamp installed. I eventually decided that i prefer the passive VVT setup, so I bought a loaded Jazz control plate on ebay an installed it last weekend.

All of the controls function as they should despite this being my first time soldering anything. (I used my fretted 44-60 as a wiring model.)

the problem:

I am getting distortion when playing even moderately hard. It's similar to the kind of distortion that happens when a battery is dying in an active instrument.

i thought maybe it could be remedied by lowering the pickup height, but it's still there. and also, why would the PU height be an issue now, but not with the J-retro?

Any other possible culprits?

in case it makes a difference:

the pickups are split-coil jazz pickups

the passive control plate has two sets up wires connecting all of the pots (the ground wire, i believe) it seems like it should only need one, (as in my other bass).

thanks for any input!
 
#2
DylanD said:
background:

I bought a used fretless Lakland 44-60 that had a J-retro preamp installed. I eventually decided that i prefer the passive VVT setup, so I bought a loaded Jazz control plate on ebay an installed it last weekend.

All of the controls function as they should despite this being my first time soldering anything. (I used my fretted 44-60 as a wiring model.)

the problem:

I am getting distortion when playing even moderately hard. It's similar to the kind of distortion that happens when a battery is dying in an active instrument.

i thought maybe it could be remedied by lowering the pickup height, but it's still there. and also, why would the PU height be an issue now, but not with the J-retro?

Any other possible culprits?

in case it makes a difference:

the pickups are split-coil jazz pickups

the passive control plate has two sets up wires connecting all of the pots (the ground wire, i believe) it seems like it should only need one, (as in my other bass).

thanks for any input!
Click to expand...

What about the amp settings? Too much gain will cause that. Too much of one part of the EQ, such as treble, bass, or mids, will also do that.
 
#4
Can you post a pic of the control plate , showing the wiring? The things interesting to know from your description are...how is it wired?, what are the values of the pots, (checked on a meter) and are they of questionable condition, or quality? what is the resistance measured on each pickup, using the 2 wires you used for hot, and ground, on each pickup, (they need to be unsoldered to check on a meter). It isn't that an instant answer would come, knowing those things, but, it could point out something clearly wrong, or odd about the setup, that you might address in getting things to sound better.
 
#6
Growlmonkee said:
Can you post a pic of the control plate , showing the wiring? The things interesting to know from your description are...how is it wired?, what are the values of the pots, (checked on a meter) and are they of questionable condition, or quality? what is the resistance measured on each pickup, using the 2 wires you used for hot, and ground, on each pickup, (they need to be unsoldered to check on a meter). It isn't that an instant answer would come, knowing those things, but, it could point out something clearly wrong, or odd about the setup, that you might address in getting things to sound better.
Click to expand...

Thanks. here is a photo. I don't currently have a way to test resistance. I have no reason to believe that the quality/condition is bad. Here is a description of what i bought from Sigler Music:

Loaded Control Plate for Fender Jazz Bass, complete with vintage style knobs and wiring. Vintage style knobs 3 - 250k CTS Pots 1 - 1/4" Switchcraft jack 1 .047mfd capacitor Vintage style cloth wire Mounting screws This is a direct replacement for the Fender Jazz Bass and features standard wiring...
 

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#8
Well, that's a nicely done control plate, with good components, it's doubtful from the looks that it's a problem. I do have one question, I can't see clearly, on the middle pot, the small black wire coming from the pickup should be soldered to the middle pin on the pot, its hard to tell if it's on the middle pin, or the same pin as the white wire, other than that, if I was troubleshooting, I'd want to know what the resistance is across each of the pickups, by disconnecting one wire on each pickup, and measuring across the 2 pickup wires on each one. disconnect a wire so you get only the pickup, and not the control circuit, maybe borrow a meter. I've bought from Sigler, and have always been happy with the stuff they send, good people.
 
#9
The pickups could possibly be a factor because the preamp was buffered, balanced to send a specific lvl. signal, it's a possibility, and the preamp was balancing things, and the signal from the pickups distorts without it, if they are standard type passive j pickups, and not a set designed to work only with that preamp that isn't the case.
 
#11
I appreciate your responses!

I see what you mean...yes, the black wire is on the middle pin.

Growlmonkee said:
The pickups could possibly be a factor because the preamp was buffered, balanced to send a specific lvl. signal, it's a possibility, and the preamp was balancing things, and the signal from the pickups distorts without it, if they are standard type passive j pickups, and not a set designed to work only with that preamp that isn't the case.
Click to expand...

That was a thought I had as well. they are split coil pickups. I'm not sure of the make, but i think they may be Hansons. do split coils have more output than singles? If so, I could see how the existence of the preamp would be adding more resistance (I'm not sure if that is the right word to use here) and putting the output at a more manageable level.

would a possible solution be to just lower the pickups until it stops distorting? I would have to cut down the foam in the cavities.
 
#12
Split coils , or single, it's the number of windings and magnet type that determine the output, I'm trying to help, but, would be far better if someone who knows the facts about the Hansons, I'm no expert here, I don't. Raising and lowering the pickups would affect the output, but, it may or may not be enough, of course if you try that, be careful with the pickup screw length, that they don't poke through, (it can happen) I use layers of neoprene mouse pad to get height, cut to fit the cavity, remove or add a layer as needed
 
#13
It's not only pickups that are too hot that distort, see if you can turn volume on the bass, and amp up to light your amp's input clip light, if you need to turn the amp way high to do that, the problem could be low output, and too much of your amps pre section to get lvl up, that would be the pickups to blame also
 
#15
Thought of one more thing, not being familiar with the pickups, you could try putting that black wire on the middle pot to ground, and the red to the middle pot lug, they could be out of phase, it won't hurt anything to try, but it will sound horrid if it was right to begin with, forget this, you're wired correctly, I looked it up
 
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#16
It's a long-shot, but in some rare cases, little fuzzy distortions with passive guitars can be caused by other things - loose winding wire vibrating, some metalic debris attracted to the magnets (fine steel wool from polishing frets for instance), a loose pickup cover (the metal type), a dry solder joint, tarnished switch or jack contacts, etc etc...

I'd isolate the new controls by soldering the pickups individually straight to the jack. If the distortion is not there, I'd reheat and flow all the joints of the new controls with good new (flux core) solder. Be sure to use heatsink clips on the pot lugs, and also turn the iron all the way up for the earths.

If the pickups distort, sans controls, remove the covers and check for debris around the magnets.
 

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