Strat noise

[caspercody]

I bought a Fender Start Affinity, and when I have the switch in the first, third, or fifth (one single pickup position) I get a lot of noise (hum). But when in the second, or fourth (two pickups used) I get little to no noise. My question is would this be the cheap pickups? A bad ground or wiring? Or is it because using one pickup is amplifying the single more than when two are being used (I know I have bad AC hum in my house)?

Just curious before I open it up on what to look for.

Thanks
Rob

[deltafred]

I bought a Fender Start Affinity, and when I have the switch in the first, third, or fifth (one single pickup position) I get a lot of noise (hum). But when in the second, or fourth (two pickups used) I get little to no noise. My question is would this be the cheap pickups? A bad ground or wiring? Or is it because using one pickup is amplifying the single more than when two are being used (I know I have bad AC hum in my house)?

Just curious before I open it up on what to look for.

Thanks
Rob

Strats have single coil pickups so when you have only one selected they pick up magnetic hum from amps, cabling, lighting rigs etc.

The middle pickup is reverse wound with reversed magnets so when you have 2 coils selected, positions 2 and 4, then they are humbucking as the hum is cancelled but the signal is not.

It has nothing to do with the cost of the pickups, you have a typical Strat and unless you go for noiseless pickups you will just have to live with it.

Moving away from the source of the hum is usually the best answer.

[lolbou]

Stock Strat wiring sucks. You'd better wire it properly (star grounding) and eventually shield it...

[bajaman]

One thing that is definitely worth doing (forget star ground wiring ) is to replace ALL the individual pickup leads to the selector switch and the leads from the volume pot to the output socket with proper shielded coaxial cable.
I did this to a friend of mine's Strat last week and the difference in background hum and noise made a HUGE difference.
Strat pickups use a white wire for signal and black wire for ground. Carefully remove (or snip at the pickup) these wires and replace with shielded cable (shield goes to where the black wire was attached to the pickup) from the pickup to the selector switch. I tie all three shields together and attach to a ground point (back of the volume control) with a small piece of the black wire taken from the pickups.
Don't forget to replace the white and black wires connected from the volume control middle pin to the output socket with a piece of shielded cable as well
Although the hum will still be there on positions 1, 3 and 5 of the switch, it will be significantly lower in level than it was before adding the shielded cable.

PS: I have tried shielding the pickup completely with copper foil but found this has a damping effect on the coil and can alter the feel and response of the pickup in a detrimental way, BUT there is nothing wrong with shielding the entire pickup and control cavity of the guitar with self adhesive copper foil or painting with conductive paint and attaching to ground. However before resorting to these measures - try the shielded cable replacement tips I mentioned first.

Cheers
bajaman

[lolbou]

(forget star ground wiring )

How come this can be worse than the stock wiring from a grounding point of view? At least it gets rid of ground loops? I'm not an amp man enough to be sure of what a proper star grounding (or am I using a wrong word for this concept?)...

BUT there is nothing wrong with shielding the entire pickup and control cavity of the guitar with self adhesive copper foil

Just spent my afternoon on this (no wife and no kid for a day!! ). I rewired my two strats (an Applause one and a 1997 Standard). I had the cavities and plates shielded with adhesive copper foil some years ago, but at the time I left the stock wiring : it didn't change a thing .

So I went for the complete workout of the circuitry (with help from www.guitarnuts.com). I left the 400V cap out of it though...

My US Strat turned out this way:

The wires are white and coloured in my Strat. The back of the volume pot is the star ground. That is (at least to me ) that no signal flows in the cavity shielding. The signal escapes the cavity from the volume pot in its own shielded cable straight to the jack.

Result : HUGE improvement, really. On the clean channel, there is almost no difference between the 1,3,5 positions and the 2,4 ones. Though it still hums a tiny bit (come on, it's a bloody Strat!).

My Applause turned out this way:

I have no pics of the original wiring, but I messed with it when I got the guitar back in 1998. I added a switch to have all three pickups in the same time and wired the tone control for bridge pickup. I used big wire and the worst soldering iron on the planet back then (plus my bad ability at the time)... Oh, and the selector is a US strat one.
When working on it, I had to change the pickups wires because they were all dried up and impossible to work with. The stock pickup wire was a two-conductor+shield, with the shield and ground wire of the pickup linked together at one end (volume pot) and the other end of the shield soldered to the pickup bottom plate. I replaced all three with a single shielded wire, and used the volume pot again as a star ground. I removed the stock 820p cap across the volume pot but left the two 47n for tone.

Result : good improvement too, maybe not as dramatic, but while the the PU wires are shielded in this one, it hums more than the US on 1,3,5 positions. Also the Applause as a higher output. But the two can't really be compared anyway...

But still, both worth the effort considering the good results. I have to get my first guitar back to rewire it with no cavity shielding but shielded wires only as bajaman said so I can compare, but the PUs are even worse...

[Ben N]

Stock Strat wiring sucks. You'd better wire it properly (star grounding) and eventually shield it...

You can easily star ground AND use shielded cable by using two-conductor shielded, such as mic cable.

[lolbou]

You can easily star ground

Unless it is something to forget about... But yeah, you're obviously right, so I think it's better to go for:

1 - shielded wire for PUs.
2 - proper grounding scheme.
3 - cavities shielding last (but maybe not least).

... and check improvements inbetween if any...

[mojah63]

I have Squires too and rewire them like the pictures above. I also replace all the pickups and
electronics... I tried shielded wiring a long time ago and it didn't do much for me.. Before you get too worked up into this check all the ground wiring from the tremolo claw and the output jack wiring esp the ground wire. I've found the stock output jack on Squires to be cheaply made with the grounding ring a bit loose and also the soldering to be suspect everywhere.. I just can it all but I know you may not have the $$. Single coils will have some noise but with a good solid ground it shouldn't be too much a problem. I gigged out a lot in the 90's with a reissue '57 Strat and the noise wasn't that bad.

[phatt]

One thing that is definitely worth doing (forget star ground wiring ) is to replace ALL the individual pickup leads to the selector switch and the leads from the volume pot to the output socket with proper shielded coaxial cable.
I did this to a friend of mine's Strat last week and the difference in background hum and noise made a HUGE difference.
Strat pickups use a white wire for signal and black wire for ground. Carefully remove (or snip at the pickup) these wires and replace with shielded cable (shield goes to where the black wire was attached to the pickup) from the pickup to the selector switch. I tie all three shields together and attach to a ground point (back of the volume control) with a small piece of the black wire taken from the pickups.
Don't forget to replace the white and black wires connected from the volume control middle pin to the output socket with a piece of shielded cable as well
Although the hum will still be there on positions 1, 3 and 5 of the switch, it will be significantly lower in level than it was before adding the shielded cable.

PS: I have tried shielding the pickup completely with copper foil but found this has a damping effect on the coil and can alter the feel and response of the pickup in a detrimental way, BUT there is nothing wrong with shielding the entire pickup and control cavity of the guitar with self adhesive copper foil or painting with conductive paint and attaching to ground. However before resorting to these measures - try the shielded cable replacement tips I mentioned first.

Cheers
bajaman

A Brilliant simple explanation,,, Just don't expect a medal from the cork sniffers who like to think their sacred strats with reverse wound silk cloth covered wires sound better.

Re copper cladding:
Yes around a pickup they may effect the sound but then a lot of older pu's had German silvered top caps (A type of brass) which slightly muted the very hi frequencies. (part of the magic of early pu's) but then heavy rock came and everyone ripped the covers off to get MORE of whatever it was they where searching for.

Re Cavity;
Well most noise is likely to be mains hum and mild steel is the cheapest way to stop Magnetically induced pickup. (tin cans are cheap as,, hint)
I think Cooper is better for blocking RF stuff but maybe Not so good at magnetic shielding.
Phil.

[DaveKerr]

One trick to try if you're wrapping a pickup with copper foil is to not have a complete conductive loop around the coil - put a non-conductive insulator between the layers where they overlap. Pretty nice, concise thread here.

I'd pay closest attention to deltafred's first reply - it's more likely the magnetic hum that's bothering you if positions 2 & 4 are clean to your ears. Any noise being picked up downstream from the coils that shielded wire/cavities would protect would be audible to you regardless of the switch position, wouldn't it? I'm not arguing against the benefits of shielding, just wondering whether it's the answer here. Stand away from computers, florescent lights, the transformers on your amp, etc and you might hear some improvement.

[caspercody]

Thanks everyone!! I have a little reading to do here with these posts.

Question, what gauge shielded wire is best? Do you ground the shield on both sides? Is it best to use a single conductor cable?

Thanks
Rob

[DaveKerr]

To the middle question, ground the shield only at one end - somewhere in the control cavity where you're tying your grounds together. Make sure you get the braided stuff, not the foil shield.

[mojah63]

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If your following Dave's advice it would be 2 conductor plus shield. 24 guage or even smaller would do. You could use old mic cable but that may be a bit big but cheap. Tying the sheild on one end ,vol pot, eliminates a potential ground loop and makes the shielding work thats good. Check the all the stock wiring & grounds 1st.

[JiM]

(forget star ground wiring )

How come this can be worse than the stock wiring from a grounding point of view? At least it gets rid of ground loops? I'm not an amp man enough to be sure of what a proper star grounding (or am I using a wrong word for this concept?)...

There's no need for star grounding inside the guitar, as it already has a single ground point : the jack sleeve. Any current flowing out of the guitar comes back there. You can connect the shields in any way you like, as long as they're properly grounded (low resistance with regards to the jack sleeve) they will act as a shield.
I don't know why the guys at Guitar Nuts keep believing in star grounding a guitar ... and i'm not alone :
http://searcystringworks.blogspot.com/2 ... -myth.html

In a amp, it's a different story, because there's massive DC currents involved : several active circuits shall have their own current return path to ground, i.e. making this point a star. Otherwise, the current from one stage can influence another one, because the ground plane does have a tiny bit of resistance.
More info: http://www.aikenamps.com/StarGround.html

[deltafred]

... I don't know why the guys at Guitar Nuts keep believing in star grounding a guitar ... and i'm not alone
...

No you are not alone.

I was wondering (but not enough to calculate it) just how much volt drop you would get in a guitar to justify star grounding, it must be at least a few pico volts.

[lolbou]

Thanks for the reply Jim . I knew it was more an issue of terminology. I do get the one output = one ground path stuff...

But still, to me, stubbornly , there's a ground loop whenever you can reach two different points that are ground using two different paths, and I try to avoid this in every way I can. It might be stupid, but it sounds like a good way to consider things from the start. Again, this may not be too critical, but the voltages and current are low in a guitar, aren't they?

And if you look closely at the stock Strat wiring, you can see that the pot casings wires added with the - famelic - aluminium shield sticked to the pickguard offer two different paths to reach the same single ground point.

I can't tell now if removing these two wires would help at once. If I could have the Strat stock again, I would try to improve it step-by-step, and record the noise... Anyone offering his axe??

But now all the electronics in my strats are in a shielded cavity, and the signal makes its way out in a shielded wire to the output jack. I wonder if using a shielded pair for pickups would be a big improvement since it's already nice and quiet. Not dead quiet in single coil positions, but really quiet anyway.

[lolbou]

it must be at least a few pico volts.

I guess AC picovolts can turn into audible hum when amplified...

But yeah, playing your electric guitar unplugged to kill hum can't be beat!

[JiM]

And if you look closely at the stock Strat wiring, you can see that the pot casings wires added with the - famelic - aluminium shield sticked to the pickguard offer two different paths to reach the same single ground point.

In my Telecaster, there is a ground wire running between the pots, even if the - beefier - control plate already connects them. And it's as quiet as a Tele can be.
However, adding aluminium foil at the back of the pickguard, and connecting it to ground, did remove entirely the noises made by static charge building up on the plastic.

About amplified picovolts : you're right, but other noise sources (including EMI) would be annoying long before that.

[caspercody]

Okay, I ordered the copper tape and waiting for it to arrive. I did re-solder it using shielded cable, and it did lower the hum. Curious to see if adding the tape will help much more.

Anyways, I see I have 500K pots with the .033 cap. But a lot of the wiring diagrams I see online use 250K pots with a .022 cap. Is there much difference in sound with these two different types? Ir does this not matter much?

thanks
Rob

[phatt]

Okay, I ordered the copper tape and waiting for it to arrive. I did re-solder it using shielded cable, and it did lower the hum. Curious to see if adding the tape will help much more.

Anyways, I see I have 500K pots with the .033 cap. But a lot of the wiring diagrams I see online use 250K pots with a .022 cap. Is there much difference in sound with these two different types? Ir does this not matter much?

thanks
Rob

It's a two edge conundrum chum.
The moment some hobby geek replaces the 250 pot with 1 meg he gets more bandwidth,,, more treble gets through and he thinks he's ahead.

Understandably he thinks he has improved things,,, or has He? As what he may not fully grasp is that he has also made the volume pot much more sensitive to treble loss if he turns down the passive volume.
(Some other things also happen but lets keep it simple for now)

So think very carefully before those mods.

Phil.