Noisy Lace Sensor pickups

[Mick Bailey]

I have a Strat in right now that has an intrusive hard-edged 50hz buzz. It's fitted with blue (neck), silver (middle) and gold (bridge) Lace Sensors, and a TBX tone control. With any motor running or fluorescent lighting it's really loud - pretty much unusable - especially compared with a Tele or regular Strat. The owner says it used to be fine and just started doing this. The tonality and output levels are good.

Initially I though this was a grounding issue. The guitar has clearly been worked on, as the grounds had previously been lifted from the volume pot and inexpertly re-soldered. I fixed those, plus metered through the grounding and inspected the wiring to make sure everything is OK. It checks out fine and the cavities are factory screened and the pick guard is foil screened on the back.

So as a final test I disconnected each pickup and connected them individually to my bench amp - no guitar wiring connected. They all buzz on their own. At the moment I'm stumped.

Has anyone got any ideas?

[big_teee]

It still sounds like a ground & shielding issue.
Check the bridge ground, make sure that the strings are acutally grounded.
I turn the volume pot on high, plug in a guitar cord and check ohms through the guitar.
Make sure the foil reads ohms continuity from the plug sleeve ground to each foil, pot, & switch, metal component.
T

[Justin Thomas]

If the guitar has been "worked on" in the past, have you gotten a wiring diagram from Fender about how it goes? I forget the specifics, but I'm fairly certain there was a factory model with those specs... does it have 22 frets & was made in USA? I know it would be an early to mid-90s model... Fender site should have the schematic... Just a shot.

Justin

[big_teee]

If your down to testing one pickup and strings, playing direct into your amp?
A diagram won't do you much good, it wouldn't hurt, if you can find it. I couldn't.
You can also take a pickup out of the guitar and hook it direct.
I do that with new pickups to check phasing, and microphonics.
I wave it around the amp and compare it to good known pickups, for noise.
I suspect a ungrounded bridge, or a high resistance ground to the bridge and strings.
That should be fairly easily to find.
There is also the option to put one of the lace pickups in another guitar.
Do a Napoleon trouble shoot, Divide and conquer.
T
** I found this lace link.
http://www.lacemusic.com/pdf/1.pdf

[rjb]

So as a final test I disconnected each pickup and connected them individually to my bench amp - no guitar wiring connected. They all buzz on their own. At the moment I'm stumped.

Having, to my knowledge, never been in the same room as a Lace Sensor, it is silly for me to answer.
But I happen to be a silly guy.

How is your test setup wired? Pickup leads soldered to 1/4" jack, then guitar cable to amp?
Orange lead to tip, white & green leads to shield?

In the linked diagram, it looks like a wire from inside the pickup is soldered (riveted?) to a brass shielding plate.
Is that wire intact?

That's all I have.

-rb

[Mick Bailey]

The wiring and grounding checks out fine as far as I can see. It is a factory spec 22 fret, roller nut USA model. The pickup grounding plates are all grounded, ground tab is connected to the cavity screening, pots have linked wired grounds, switch has a separate ground tab, claw is grounded, pick guard is foil backed and grounded. I've checked the socket, pots and switch for anything untoward and can't see anything wrong. The pickup connections are as per the Lace wiring diagram.

I've since completely removed the pickups and tried them on the bench away from the guitar. They're all far too noisy compared to any other single coils I have. They also loudly pick up the tick from my electric fence energizer. With the other pickups I've tried this is either barely perceptible or absent. I also noticed that touching the ground doesn't have as great an effect on noise reduction as with the other pickups. So for testing the pickup is removed from the guitar and connected orange lead to hot, green/white to ground. Just as they connect in the guitar.

Given that the problem exists in isolation from the guitar I'm thinking the pickups are inherently noisy. The last Lace Sensor guitar I had in was as quiet as any humbucker model, so there's a conflict I'm wrestling with and trying to rationalise. Especially as the owner says it suddenly started doing this. That's mighty strange considering all three pickups are involved

[big_teee]

All pickups are more noisy when out of the guitar and away from the grounds and shielding.
I don't pretend to know how a lace sensor works, & why all the wires?
Here is a little on them.
https://sites.google.com/site/stratk...28Small%29.jpg
Something must have broke down.
If you separate the white and green?
Maybe you can figure out if there are more than one coil?
If so maybe you can wire them out of phase.
wax potting couldn't hurt?
Good Luck, and please let us know if you come up with something.
T

[ric]

Retracted, the more I thought about it the stupider my post seemed, oops.

[rjb]

Especially as the owner says it suddenly started doing this. That's mighty strange considering all three pickups are involved

I bet the answer will become clear if you can get the owner to tell you what he was doing just before "it suddenly started doing this".

[rjb]

I just went Googling and found some pics (attached below) & info on the Sensors' internal workings.
https://web.archive.org/web/20100213...nsor_specs.php

Is it possible to check continuity between the green wire and the "Radiant Field Barriers" (AKA shields) along the sides?
From your description, it sounds like the "RFB"s might be floating.
(Which, of course, couldn't happen unless someone d*cked around with the pickups.)

---

Addendum:

FWIW, here's a report on the dissection of a late-model Sensor. Unfortunately, they're now encapsulated in epoxy.
The guts of a recent vintage Lace Sensor Gold | Fender Stratocaster Guitar Forum
(I didn't notice until the end that the contributor is considered a local pariah.)

[Mick Bailey]

All pickups are more noisy when out of the guitar and away from the grounds and shielding.

I'd expect that, but when comparing with a random selection I have to hand they're excessively noisy in a like-for-like bench situation. Even compared to some Chinese fake Tri-sonics that were pulled for the insane noise they picked up - they're even worse than those.

Coincidentally, I woke up thinking about splitting the white and green and taking a further look at the pickups. Something doesn't add up, and the previously lifted grounds are a clue. The owner rang me up and I asked him about the pigeon-crap soldering on the back of the pots. He says he'd noticed that and he was going to contact the previous owner to find out more (he's only recently had the guitar).

[big_teee]

By what your saying, sounds like the pickups have never been quiet?
So try splitting the green and white, and check ohms continuity, and see if there are two equivalent coils.
the soldered ground to the brass plate may be part of one coil.
find what reads to it.
Then see if you can find the other coil.
If you can establish that, then try reverse wiring one coil.
Then retest.
T

[rjb]

Lace Sensors are single coils.
They also make a fully humbucking pickup (essentially 2 Sensors side-by-side) called the Dually.

[big_teee]

If they are SCs, then why all the wires, and the pictures show the two micro combs.
I guess the winding is around that. You never see any real exploded view pics of the coil.
Just the propaganda photos from Lace.
If they are truly SCs, then they are supposed to hum!
Put some small rail blades in there, I know they are humbuckers, I make those.
And, they are amazingly quiet!
T

[Fluoroscope 5000]

I see two wires for the coil, and one for the chassis ground. There was an exploded view on the site years ago. I guess they don’t want to give anything away now. It’s really not so unusual. There are Steel plates on either side of the coil for shielding. The bobbin is the metal comb structure. The design channels the field tightly down around the sides of the pickup along the shield plates to center the field directly over the coils for improved efficiency. They need to be up close to the strings for that reason, making the neck pickup notes along the neck more imbalanced than an AlNiCo V pole pickup with a longer field throw. They are a little quieter than Fender SC’s. I tried them when they first came out and was discouraged that the florescent shop lights caused so much buzz. The thin shield plates can only do so much. They are listed as having very low self resonance per inductance values. Perhaps they roll off more gradually than most pickups? They do seem midrangy, but may have stronger fundamentals than most SC’s.