Problem #1 In the original QTB article it says to use "twin-conductor shielded (two conductors plus shield) audio cable" and to trim the inner shielding braid from the pot's end, (leaving it inside the outer jacket...?), and to then solder the other end of the braid to the gnd lug at the output jack. I don't understand the reason for this: - The inner wire is already soldered to both the jack and the pot's lug and then on to the star assembly. - I understand the shielding braid would work if both ends were soldered, but only one...? I don't get it. - I also soldered a wire connecting the copper in the output jack cavity to the bottom of the pickguard cavity to keep continuity. This wasn't in the instructions, but I thought it made sense, does it?
Problem #2 I have throtoughly shielded my strat. I also covered the back of the backplate, and soldered a wire from the main front cavity to the output jack cavity to have full continuity in the shielding. I don't get 60hz low frequency hum, but I do get very noticeable HIGH frequency hum which is annoying, specially for recording. Is shielding capable of removing this High frequency hum or do I just have to resign and assume it's the nature of "the beast"? I have searched the web for a long time and most attribute this high frequency noise to RFI. I also tried shielding the pickups surrounding them with teflon, then copper tape and soldered them to the star grounding. No reduction of the high frequency noise and a BIG suck of tone. I inmediately reversed it. Any suggestions?
(EDITed by sumgai to combine threads - the second problem was moved from a topic started in Reference Articles.)
The braided shield is only connected at one end in the same way that the rest of your shielding is only connected at one end.
This is a gross oversimplification of what's actually going on, but you can think of the entire shielding system as being one big antenna. An antenna is only connected on one side, right?
Basically, your pickups also act as big antennas- they'll pick up the signal from from your strings, but also extraneous noise. You hear the noise because your pickups are also connected to the signal-carrying components of your guitar.
By enclosing the pickups in a bigger antenna (your shielding) which is not connected to the signal-carrying circuit, the idea is that the shielding should pick up the noise and ground it out before it gets to the pickups.
- Can I keep the tremolo wire soldered to the backplate and then to the copper foil?
If I touch the jack plate it goes away and is dead silent!
Is this a Strat-type guitar with the "canoe" jackplate? Usually, the braided shield to the jack should take care of this, but there are some other things you can try.
First, unscrew the plate. Make sure the plate isn't touching any connections, including the braid. Try playing with the jack just hanging in midair for a sec. Does the noise go away?
Second, if that doesn't result in a "Eureka" moment, try using a pair non-conductive washers to isolate the jack from the plate. I use a strip of plumbers Teflon tape around the threads on the jack, then a non-conductive washer on either side. The tape must not extend past the washer and onto the portion of the threads you'll be using to tighten the hexnut.
Third, you can simply run a separate ground wire from the plate to your grounding point.
One of these things ought to take care of it.
Edit: Ack! Ninja'd by Sumgai's editing!
The two conductor braided cable ought to be enough to shield the jack cavity, your extra shielding in there may be causing the problem.
Second, I used my privileges as an Admin to move your other topic out of the Reference Articles section, and combine it here. That way we can all be sure that we're all in the proper place in the Nutzhouse!
Now let's address your concerns:
Problem #1a: You generally connect both ends of a wire to complete a circuit, so your question is valid. In John Atchley's instructions, he's telling you to solder only one end to ground (at the jack) and clip off the other end - this is an effort to avoid ground loops. While John's heart is in the right place, in fact his concern over such things is unfounded, as revealed by many members here over the years. In short, if you wish to do it his way, you'll be doing it with his blessing. This has the added advantage of being able to troubleshoot it more easily in the future, because all the wiring is "per the instructions", and you don't have to remember what changes you made.
However, if you choose to follow your own conventions, which are pretty much what we call "Best Practices" around here, then you'll be good to go - there'll be no deleterious effects on your circuitry.
Now, I'm a bit confused here. You state: "- The inner wire is already soldered to both the jack and the pot's lug and then on to the star assembly." Is this one of the two inner wires within the braided shield? If so, then I don't think things are going to work well if it's connected to the star grounding washer. That's supposed to be for (isolated) ground connections only, whereas the inner wires of shielded cables usually carry signals, not ground connections. Clarification is needed, please.
Problem #1b: Soldering a wire to give continuity between shielded cavities is a good idea. I, along with others here, have been mildly surprised to note that John A. doesn't mention that at all.
But just be aware that this connection is for shield continuity, and is not meant to carry any signal ground connections. Shielding is notorious for not being a real good conductor of signal-quality waveforms, althought it works great on spurious radiations of the hum-and-buzz kind.
Problem #2: You've done all the right things we would normally suggest. That teflon (for insulation) and tape thing was inspired, but the laws of magnetics gotcha - a giant hysteresis loop was formed around the pickup (meaning, around the magnetic field), and that's a cardinal no-no. While I don't suggest it in this instance, next time you get the urge (perhaps on a friend's guitar), leave a bit of a gap between the ends of the copper tape, perhaps 5% of the total length - that should solve the tone-suck issue.
We need to know a bit more about your noise. RFI can be absolutely anything, in terms of frequency. How high is high? Is it a howling that stays rock steady, or does it waver in pitch? Waver in volume?
Here's the rundown on locating the problem, we'll get to fixing it after this step:
1) Does it occur with an clean connection from guitar to amp? No stompoxes or other effects, and the shortest cable you can get away with. And the cable must be known to be good, as in, not all banged up from years of touring... you know what I mean.
2) Does it occur only under certain circumstances such as a high-gain stompbox is in the signal path? Or even if the amp is just turned up to ear-bleed territory?
3) What happens when you move around?
4) Persuant to that, what happens if you move to another location, not in the same building, but in another house/practice room/bar/etc.? The opposite of that would be, what happens to a friend's setup when he/she comes over to your place? (Assuming that your problem originates right there in your home.)
5) Combining 3) and 4), how about exchanging guitars with your amp and cable? Exchanging amps with your guitar and cable? You get the idea here too, I'm sure. Just keep track of what combinations make the squealy noise.
6) Now you can suspect your guitar, given all the above. Does this happen with all of your pickups, or only one of 'em? Do(es) the squealer(s) make "funny" noises when you tap the pickguard? Even at low volume?
By now I think you've gotten the idea of how to look for the culprit, and what to fix when you find it. But if after all that you still have an issue, then you know where to ask for more help, right?
(EDIT: ack! ninja'd by newey. There goes my point about Problem #1a. (Which I've now renumbered.) I've got to learn to think/type faster! )