4002 Varying output

[Kopfjaeger]

I received my reconstructed 4002 today. It looks and feels amazing. I do have an issue. The E string is booming and gritty, just like my other 4002. The A string is anemic in comparison. Huge volume and tone drop off. This is equally true in both the bass and treble pups. Isolating one or the other and the anemic output is clear. The difference is not so noticeable while playing finger style but with a pick, it's like night and day. The D & G strings sound strong, much stronger than the A.

This bass was in water for a part of it's life and suffered mightily. While resistance wise the pups were in spec. it it possible they sustained damage that was not evident until energized??

The output drop sounds sort of muffled with a slight echo.

Thoughts??

Sepp

[cjj]

I'd suspect the strings first. Try another set just to be sure. Or at least a different A string...

[Kopfjaeger]

CJ,

I should have mentioned that I swapped the A string for two others. No difference.

Sepp

[cassius987]

I don't understand what you're saying. Is it only a problem when the pickups are soloed, when both are on at the same time, or with all of these settings?

If it's just when they're both on, I bet it's a phase issue. Happened to me once.

If it's independent of the pickup settings you may need to give your bass a better setup. Due to radiusing the D and A strings are at a disadvantage in terms of being sensed by the pickup. Further the split coil means if the A or D is a little too close to center it could be on the edge of the magnetic field. Or perhaps there is a mechanical issue at the nut or bridge. You could also try upping the gauge a bit.

[Kopfjaeger]

Joshua,

With both pups on the A string is anemic. When soling the pups, the A string, on either the bass or treble pup, it's still anemic. The E string is loud and classic 4002 growl. The A string is a muted kitten in comparison.

The string gauge I chose for the bass, .106- .079.-.059-.043 was deemed a bit too much for the neck so Ernie Ball Extra Slinky .095-.070 -.060-.040 were installed. I swapped out the A with another extra that was close in gauge. Same results. I then swapped out the .70 with a .079. Same result.

No change in tone when I apply pressure to the string between the nut and winders.

Both are at their up most travel. The pups are still quite far away from the strings in comparison to my other 4002. I realize the radius takes the A further away from the pup than the E but the same holds true fro the D over the G and the D seems to sound fine. As far as action goes, it's about 1/8 an inch and the neck is flat.

I'll see if I can shoot a quick bit of audio to show what I'm getting.


Sepp

[Kopfjaeger]

The video is loading on my computer. While waiting, I was having a conversation with Mark Walker. he asked me to tap the pups on the cover to see if they sounded the same across the face. They don't. The treble does but the bass is very muted where the A string sits. I then noticed the pups do not sit evenly under the strings. After seeing the split coils, there is a bit of a dead spot in the center of both pups. My other 4002 has the same deal. being the pups are shading more toward the bass side it's putting the dead spot very near the A string. if I were to have a new pickgaurd made and have Tony move the pup openings toward the treble side, I'd pick up strength on the treble side. The jury is still out on the bass side. That may be a pup issue.

The foto shows how off the pups are in relation to the strings. not much but it makes a difference.

Sepp

[Kopfjaeger]

The bass pup seems to have a much larger dead spot and it's directly under the A string. I thump the area directly under the string and it makes no sound. I may still have a pup issue on the bass side but moving it toward the treble side will not be a bad step.

Now who rewinds 4002 pups??

Sepp

[iiipopes]

Your pickups do not need to be rewound.

Angles can be deceiving in photographs, but it does appear that your pickups are too far to the E string side, and the A string is getting into "no man's land" between the two magnets. Remounting the pickguard with the pickups realigned and centered on the strings should solve the issue.

[Kopfjaeger]

Scott,

I took all the screws out of the guard and shifted it over so the pups were centered properly and instantly, my weak A string issues disappeared. Now I either order a new guard from Pickguardian and have him shift the pup openings or drill new holes in the body to relocate the original guard. Guess what option I'm going to go with?? Option #!!! I can even shade the pups a little more toward the G string than center since there was no drop off of volume as I did so.

Larry has another 4002 pup set up with guard in his shop and he ran an experiment with the dead zones. His results mirrored my results. The Bass pup has a wider dead zone than the Treble pup. Possibly caused by the additional Low Z windings in the treble pup??? My walnut 4002 has two very narrow dead zones but both pups are low Z treble pups, thus giving my narrow dead zone/low Z hypothesis more credibility. Do I toy with having my bass pup rewound with the low Z coils??? Overkill perhaps but tempting just the same.

Thoughts??

The tone controls really knock the bottom out of the output when less than full on. I found this out while experimenting with it last night till after midnight!! Yeah, my rear is dragging at work today!!

Sepp

[iiipopes]

I wouldn't rewind the pickups unless they fail altogether. Another option is to get new unnotched bridge saddles and slightly offset the two pairs of strings narrower (A string a little closer to the E string and D string a little closer to the G string) to avoid the valley between the D & A strings. But for some folks, this doesn't feel "right," and centering the pickups usually does cure most, if not all, as you posted.

The neck pickup should read @ 8 to 8.5 kohms DC resistance. If it does, I especially wouldn't rewind it, because of the issues of reassembly with rivets instead of screws. The pickups won't adjust upwards enough unless the original rivets are used. See the threads about 4001 & 3 neck pickup adjustments with toasters.

I would simply move the stock pickguard to where it needs to be and be done with it, unless it exposes the old screw holes. In that case, have pickguardian make you a new pickguard with the pickup cutouts adjusted (you may have to send it to them indicating how much to adjust), and save the old plate for posterity.

If you have bone stock factory wiring according to the schematic on the RIC website, you can jumper the .01 inline capacitor like you can the .0047 on a 4001 or 4003 to add more fundamental back in. I did this on my neck pickup, and liked it so much I wired it to a push-pull on the neck volume knob with "in" being bypass and "out" the factory wiring.

Finally, I would try GHS Progressives in custom gauges you can get from Jason at bassstringsonline.com in 45-60-80-105. This is not only closer to OEM gauges, and a more even tension across the board, but the wrap metal is a little more magnetically interactive, and for me induces a stronger signal. My 4002 has worn this brand and gauges of strings since at least 1994. Recently I was trying some different strings on different basses and pulled them just to see after all these years. The Progressives went right back on.

[cassius987]

The Bass pup has a wider dead zone than the Treble pup. Possibly caused by the additional Low Z windings in the treble pup???

This is probably just a product of pickup position. The closer to the neck, the more the strings can vibrate outside the magnetic field.

[Kopfjaeger]

Scott,

While I thought the posted fotos of the 4002 pup guts that Jdog posted were , "neat", I never thought they would have such an impact to me and my instrument! I mean my walnut 4002 plays and sounds like a dream. Ignorance is bliss and I too thought my MG 4002 would perform reasonably similar. Who would have known that pup placement was so critical on the 4002?? With my new found wisdom, I now understand how these mysteries work.

For the record, my Bridge pup measured 76.48 ohms and my neck pup was at 7.85. I doubt there is anything wrong with them so I'm using them as they are.

Thanks for your input and ideas! I decided not to drill a new set of holes. I've made a tracing of the original 4002 guard and moved the pups accordingly. The neck pup moved approx. 1/8 toward the G string while the bridge pup moved 3/32 of an inch in the same direction. I'm having Tony at Pickguardian make the new guard in black plexi. I do not like the lack of rigidity of the reproduction material he uses for his 4002 guards. The wide spacing of the screw holes allows gaps to form and the guard actually pulls away from the instrument mid span. I think the plexi will be a bit more rigid. 100% correct?? No but a small departure IMHO. I will hang onto the guard, although I imagine it can fetch a nice price on the open market. I did not want to drill another set of holes in this pristine instrument to move the original guard but that is a viable option if I really hate the new guard.

Joshua, the neck pup on this instrument as well as the one Larry now has in his shop has a very similar "dead zone". Both neck pups do not respond well to the "amplified tap test". Larry marked the area, with tape, on both pups where the output is lost and seeing the bridge and treble pup side by side really makes the wider "dead zone" of the neck pup stand out. Since my walnut 4002 has two Low Z wound pups, both have the same narrow "dead zone" as both bridge pups in the other two examples. I don't think it is a coincidence and I do feel the low Z wound coils either bulk up the strength or increase the field enough to reduce the width of the "dead zone". Perhaps the low Z in the neck position and the neck pup in the bridge position would be more forgiving, but that's just not the way it works.

Sepp

[Kopfjaeger]

Scott,

While I thought the posted fotos of the 4002 pup guts that Jdog posted were , "neat", I never thought they would have such an impact to me and my instrument! I mean my walnut 4002 plays and sounds like a dream. Ignorance is bliss and I too thought my MG 4002 would perform reasonably similar. Who would have known that pup placement was so critical on the 4002?? With my new found wisdom, I now understand how these mysteries work.

For the record, my Bridge pup measured 7.48 ohms and my neck pup was at 7.85. They are slightly under the 8 ohms you posted but I doubt there is anything wrong with them so I'm using them as they are. I also had Dane put in a push pull pot to drop out the cap!! Thanks for the nifty idea you gave me!

Thanks for your input and ideas! I decided not to drill a new set of holes. I've made a tracing of the original 4002 guard and moved the pups accordingly. The neck pup moved approx. 1/8 toward the G string while the bridge pup moved 3/32 of an inch in the same direction. I'm having Tony at Pickguardian make the new guard in black plexi. I do not like the lack of rigidity of the reproduction material he uses for his 4002 guards. The wide spacing of the screw holes allows gaps to form and the guard actually pulls away from the instrument mid span. I think the plexi will be a bit more rigid. 100% correct?? No but a small departure IMHO. I will hang onto the guard, although I imagine it can fetch a nice price on the open market. I did not want to drill another set of holes in this pristine instrument to move the original guard but that is a viable option if I really hate the new guard.

Joshua, the neck pup on this instrument as well as the one Larry now has in his shop has a very similar "dead zone". Both neck pups do not respond well to the "amplified tap test". Larry marked the area, with tape, on both pups where the output is lost and seeing the bridge and treble pup side by side really makes the wider "dead zone" of the neck pup stand out. Since my walnut 4002 has two Low Z wound pups, both have the same narrow "dead zone" as both bridge pups in the other two examples. I don't think it is a coincidence and I do feel the low Z wound coils either bulk up the strength or increase the field enough to reduce the width of the "dead zone". Perhaps the low Z in the neck position and the neck pup in the bridge position would be more forgiving, but that's just not the way it works.

Sepp

[iiipopes]

Any word on the replacement pickguard?

[Ashgray]

Hi Sepp

A thought occurred to me that would test out your theory of the dead spot under the A string - try turning both pups through 180 degrees. If the dead spot moves to under the D string, you're right, and a replacement pickguard that would centre the pups under all four strings is likely to be successful!

I actually managed to replicate your problem to some extent recently when I needed to adjust the rods of my own 4002, following a change of string make and gauge. I took the opportunity to remove the pups from the pickguard and manually re-positioned them sightly out of alignment, as per your photo. I experienced a definite drop in power and tone from the A string - not serious, but certainly noticeable enough to suggest that the theories in the posts above may be correct.

Ash