Need advice/help...

[sander]

Hello all, newbie here.

I've got a Strat copy with 2 singles and 1 humbucker.
Recently I've changed the bridge stock humbucker for Duncan SH-4 and the middle single for Duncan SSL-1. Everything strictly according to standard wiring diagrams. I've also did the shielding (using aluminum foil).

Well, I must say, the noise level for all my pickups is quite equal now. Unfortunately not equally low... ;]

I star grounded everything (at least I think so... :/ ), however not to a ring but just to the volume pot shell. Didn't grounded both the tone pots via wires, assuming that connection to the shielded pickguard is enough...

Now, what the symptoms are...

It seems that opening gain/volume builds up the hum more than the signal and while I can play quite comfortably at clean or low-gain settings, increasing gain causes a massive hum and its level actually gets equal to the signal level. Of course high gain usually cause a massive noise but I remember that I actually could play at certain amp settings before which are unplayable to me now, due to that hum/noise/whatever.

As I've said the noise level for all pickups, singles and humbucker as well seems to be at equal level. At bridge position, while I touch the bridge or strings the noise doesn't go quieter (as it used to) and some static pops appear (as they always did). However, the pops don't appear while any of the singles are active - with a small exception - when I touch their mounting screws.

The hum level varies depending on pickups direction in the room, however the humbucker tends to get noisier at angles at which singles are quieter...

It's definitely not a matter of reversing the leads at the jack. I checked it out and everything is correct.

A little opinion/diagnose anyone? Would appreciate any help.

Regards

[newey]

Hi Sander! And Welcome!

There are many more qualified nutz than I here when it comes to troubleshooting, and I'm sure all will jump in on this. So consider this as merely preliminary.

First of all, I'm going to assume that when you are comparing the "before" noise to the "after" noise that you have kept all other variables equal- same amp, same cable, same room, same outlet- if my assumption is wrong, it opens up other possible wormy cans.

Your description of "pops" when you touch the SC pickup mounting screws leads me to suspect a grounding problem, with three likely suspects. First, double check that your bridge ground is in fact grounded to the bridge. I've pulled that connection loose before while wiring the other end in the cavity, so check under the backplate. Second, using a meter (or even a simple continuity tester) check that you have continuity across your aluminum foil shielding, both in the cavity and underside of the guard. Finally, I'd try grounding those tone controls, even if only temporarily, to see if that makes a difference. While they should be grounded to the foil under the pickguard it's easy to chew up the foil where it contacts the pot while installing it.

Those are the 3 easy things to check that I would do first. Deeper testing will have to await word from one or more of the Gods.

[sander]

Thank you for the reply and hints.

One thing I think of - if I ground everything to the volume pot shell - do I have to connect the shielding to that shell via a wire - because it already has got, in fact, a connection to it (theoretically just like those tone pots) ?

Anyway, I'm going to look into it today and try to (hopefully) fix it. :]

Added:

Hmm... I partially solved the problem. Obviously the socket I plugged my amp in, which was supposed to be grounded, is not... And I haven't noticed that till now. :]

When I plugged the amp to a different socket, noise went down a bit. Humbucker is somewhat quieter than the singles and it responds nicely to touching the strings - some of the noise goes away and there are no pops. Singles respond to touching the strings as well, but they are buzzing a lot, so I suspect there might be something wrong with grounding. I consider re-heating all the solders, just in case...

A problem I see now, after searching this forum, are those miles of wires I've got in there. ;]

Would it be reasonable to cut them short, pleach and additionally shield with foil?

Another question is - does it matter if I star ground to a ring or to the volume pot shell if I don't use a .33uf, 400V capacitor?

[ashcatlt]

Pleach?

You shouldn't have to shield any wires which are contained within the cavity/pickguard (body) shield. Can't do anything but help, though, so long as that foil contacts the (body) shield and nothing else.

I don't think it really does matter where you decide to attach the star ground without the cap, so long as it is actually the one spot where all the grounds come togehter. I might choose the ground lug of the output jack, but...

[sander]

Thanks. Well, I just slowly come to understanding a bit of all this stuff... Please, be forgiving.

[sumgai]

sander,

In conjunction with your question in the "Homage....." thread, the cap can be replaced with a hunk o' wire, if you know you're not going to be using any tube amps. That's all the cap does, it works to prevent a certain kind of amplifier failure from harming you. If you are using a tube amp, putting in the cap is up to you. Most folks do use it, because it doesn't harm the tone in any way - it's not in the signal path at all.

Regarding your problem of more noise, not less.......

The fact that you can orient your guitar and make the noise go up or down tells me that your guitar is acting like an antenna - you're tuning for maximum effect! That says, in turn, that your shielding job it not yet up to snuff. If you can't find any obvious errors, have a buddy look at it for you. Sometimes a different set of eyeballs can see what you, the builder, can't see.

Oh, wait........ one more thing. If your coils, particularly the Hb, are sticking way outside of the pickguard, then they might be receiving the hum directly - the cavity/pickguard shielding can't help in such cases. A rule of thumb might be, if more than half the coil is exposed, outside of the shielding, then you may develop a noise problem. But that's just a seat-of-the-pants figure..... your mileage may vary.

BTW, welcome to the NutzHouse! ;D

HTH



sumgai

[sander]

Thank you sumgai, My pleasure to be here.

Buddy you say, would be my buddy then?

Here is, how it looks like at the moment. I'm not going to use any tube amps in the nearest future, but I plan to add a safety cap later on.

PUs don't stick outside of the pickguard, I would say...

Both tone pots and volume pot are in contact with shield. I put foil into all the cavities, including output jack cavity. Was it wrong?

What is still absolutely necessary for me to do then?

[sumgai]

sander,

Shielding the jack cavity is a good thing.

What you show is absolutely correct. If your rig looks exactly like that, then there are other problems, which are going to be tough to diagnose over the innerweb. Being able to see the beast in action is paramount to finding problems of this nature.

That said, aluminum foil has been known to suddenly move out of position while you're putting the pickguard back on. I'd expect resultant hum from that kind of error to be small, and not very directional, as you've pointed out. Still, you might crack the pickguard, and take a look......

I don't know zip about the Duncan SH-4, is it "open", or is it fully enclosed and that covering both metallic and grounded (to the star-ground point)?

And have you grounded the strings yet? Your first post said that touching the strings did not reduce the hum, yet touching the mounting screws of the single coils did seem to reduce the popping noises. Making sure the strings are properly grounded is your first task, if you've not yet done that.

HTH



sumgai

[newey]

Sander-

The QtB shielding procedure calls for using a shielded 2-conductor coax-type cable for the output jack- shielding the wires to the jack instead of the jack cavity is the philosophy. You should redo that according to the QtB specs. It may not solve the noise problem entirely but I'm (frankly) suspicious of your shielding of the output jack divot. A good length of wire goes through the body from the control cavity to the jack and this lies outside of your shielding scheme. So the 2 conductor shielded cable is the way to go IMHO.

[sander]

Sumgai, Newey,

I rewired everything and now it looks like at ssstonelovers schematics. The only except is I replaced safety cap with a wire and I use shared cap for tone pots.

SH-4 has a 5-conductor cable with a separate shield that doesn't carry any signal. I cut off a part of this cable and used it to connect pickup cavity to output jack cavity. I used 2 of its conductors plus soldered shield to the ground at output jack side.

I eliminated any potential shorts using insulating tape.

And you know what, nothing changed. :]

As for the strings, they are theoretically grounded. I connected star-ground ring connector to a tremolo mounting plate in tremolo cavity at the back of the body. This plate is in (it looks so ) direct contact with springs which are in direct contact with bridge.

Maybe there is something wrong with cap or one of the pots?

To be honest, I'm not sure now what the overall hum level should be really, so maybe it's all correct.

But what concerns me is that:
1) it is still behaving like an antenna, as hum level differs depending on direction,
2) when I touch the strings or any metal parts, there are no pops but neither is the hum going down (and I remember it did, back in the ol'days).

Maybe my environment has something to do with it? Should a shield make a guitar immune to such interferences or is it just decreasing the influence?

[newey]

Well, Sander, I'm out of ideas now. Sumgai is right, it's devilishly hard to diagnose noise issues over the web.

Your environment may have something to do with it. Shielding doesn't provide immunity, but it should provide a substantial reduction in noise- and you're describing increased noise since doing your mod. So something's not right.

[bpdude]

The same things are going on with my guitar too.
I've done some intense modifications to my Epi Les Paul involving some switches and a preamp (separate thread). I've also covered part of my open HB's with aluminium foil in a way that they don't make a loop (imagine the Seymour Duncan logo). The idea came from the "Zero hum star coil" thread.

Now, I wouldn't say that it is noisier than it was before, because I don't remember and I didn't measure it, but the things it does are weird:

First, the level of the noise doesn't change if I hold the strings, the jack plug or anything grounded, and It also doesn't pop when I touch it. Of course I think this is great, but I haven't seen another guitar that acts like that.

The other thing is 50Hz (times n) hum coming from the pickups.
The two humbuckers can be changed between series/parallel/split internal wiring modes. On the neck humbucker I get exactly the same amount of hum in the series mode and in split mode at the same loudness levels. Yes, a single coil is generating the same amount of noise as a humbucker. The parallel mode however is completely silent.
The same thing is going on with the bridge pickup, and it is a bit worse there. Parallel is still quiet, series a bit noisier, but the split mode is a mess.

I tried moving a frying pan around the guitar while holding the strings with my other hand, and I could filter out my CRT's noise, the desk lamps noise, but the hum didn't change at all. It is also directional.

There will be band practice tomorrow, so I can try how it works in another place. It's possible that my room is heavily polluted with noise.

[sander]

Hi bpdude,

Have you found the reason of such behavior yet?