Sheilding seems to not be working

[toneless]

Hello all,

I just recently tried shielding my guitar with foil, tape, and rubber cement. I think I did a pretty thorough job, and it seems to have continuity throughout the shielding. That being said, the guitar is back in one piece, and it sounds no different to me. The hum still gets very bad when next to cell phones, computer moniters, etc...

I haven't changed the stock wiring for the most part except for some rearranging of the tone controls (so now I got a tone control for the neck and mid pups, and the other for the bridge). Also the ground wire I had cut in the process was put back together by screwing both exposed ends into the body cavity, against the foil, using ring terminals and a short wood screw. I'm not sure, but I think the shielding might be shorted out somehow. I did a continuity test to see if the shielding might be making slight contact with the hot side of the jack by plugging in a guitar cable, pressing one side of an ohm meter to the "hot" tip of it, and the other against the bridge cavity. The ohm meter showed resistance, but that it was getting a connection. As for the ground side it showed 0 ohms, which is expected. Should I worry about this, as far as I know the hot side of the jack should be getting no connection whatsoever from the shielding.

Something just doesn't seem right with this, I'm not an electrician but I think something is wrong with my mod because I'm not seeing any great results since I modified it. Any help in tracking down the problem would be appreciated.

[newey]

toneless:

Hello and welcome. While shielding helps generally, it does not necessarily help in every specific situation.

As far as your wiring is concerned, I believe you are right, you shouldn't get a reading between your shielding and the hot side of your jack- should get an out-of-range reading. But a more definitive answer will be along shortly, so hang tight.

[ashcatlt]

The shield is connected to the sleeve of the jack. What else is connected to the sleeve of the jack? Should be one end of the pickup coil, no? And where is the other side of this pickup connected? To the tip of the jack. There is a connection. The resistance you measured from shielding to "hot" side should be roughly equal to the DC resistance of whichever pickup is selected.

Unless, of course, you've installed the "safety cap" from QTB, which should block the DC current your meter uses to test resistance.

[D2o]

Hi toneless, and welcome to GN2!

My concern when someone goes less than whole-hog with the QTB mod is that they concurrently go more than half-butt (being just the shielding and stock wiring).

When you start going half-hog, whole-butt (please, please, don't be dyslexic ... ) or otherwise, you may create issues. That is not to say that has happened here, butt ...

Does the hum diminish when you touch the strings, bridge, or anything metal? If so, did you happen to remove the wires between the backs of the pots?

If I was going to just shield and retain the stock wiring, I would also retain those wires between the pots - they are redundant grounds, but that's not all bad. I suppose they could still pose a problem, in which case you would just snip them off ... but that has not been my experience, so I would retain them in favour of eliminating them.

Based on your description, I can't tell what you've done with the wiring to the tones - so let us assume that it's okay for now. However,

Also the ground wire I had cut in the process was put back together by screwing both exposed ends into the body cavity, against the foil, using ring terminals and a short wood screw.

I don't know if it is actually affecting anything adversely, but I'm not crazy about the idea for some reason. I would have just connected the ends together as they were and then insulated the area where it is connected (wrap it in electrical tape) ... again striving towards half-butt.

I don't know if any of this will solve anything ... more like a few questions to try to help figure it out.

You wouldn't happen to be able to post some pics of your wiring would you?

D2o

[gitpiddler]

toneless-welcome
without a photo, I would add to check the volume pot for a tab from the terminals to the case. cut it if there is one, for it connects the signal ground to the shield ground. it worked wonders for mine without adding any shielding. Mark

[D2o]

Hi Mark,

You wrote:

it worked wonders for mine without adding any shielding.

I think you are speaking of doing this in a shielded guitar, with stock wiring.

However - since adding shielding to a guitar that is already shielded is not going to accomplish much - your statement above causes me to ask if you can please confirm that?

(i.e. you don't mean that you didn't have to add any shielding to an unshielded guitar as a result of cutting this tab, do you?)

Thanks,

D2o

[gitpiddler]

one is a tele-style where the only 'shield' is the control plate connecting everything. I cut the tab on the volume pot that was robbed from an electric bass after reading the article on shielding and WOW-no more noise. the signal path shouldn't touch the bubble (shield) anywhere inside the cavity.
the other guitar is a rear loaded Kramer strat which did require an extra ground wire from jack to the volume pot case due to said lack of additional shielding. both instruments are one PU, one volume. the signal just seemed to jump out above the noise after that, plus less noise. peaces, git

[D2o]

Thanks, git

My wife keeps telling me that a simple snip is the only thing standing between me and neverending happiness ... maybe she's right.

[ChrisK]

Your guitar picks up noise from a cell phone?

[ashcatlt]

I've never tried it with a guitar, but cellphones definitely do induce audible noise into nearby systems. Not sure that they generate much noise in a rest state, but you'll hear that stuttering digital sound any time it communicates with the tower. Happens when you recieve a call or message - before and during the ring. Also happens when you initiate a call or message - when you press the send button. Even more fun, it happens intermittently - any time the phone decides to announce itself to the network and (hopefully) find the nearet tower.

I spend too much of my time in a call center (the worlds largest mobile communications carrier), and we're supposed to turn off all cellphones before we go on "the floor". This noise is part of the reason. The other, of course, is that we're expected to give all of our attention to our customers.

Which of course leads me to the best way to avoid this noise coming through your guitar: TURN OFF THE PHONE!

I'll let you get away with it if you're just messing around on your spare time. Maybe even at a casual practice or jam session. If you're on the stage or in the studio, though, there's nothing like something vibrating in your pocket (and blasting through your amp) to take a person completely out of the moment of what otherwise might be an inspired performance.

It wasn't but 10 years ago that most of us expected and accepted the fact that we would be out of contact the moment we left our home.

I'd also like to mention that you're never going to eliminate the noise from your rig. The best you can hope for is to minimize it. Possibly more appropriately, you're looking to maximize your Signal:Noise ratio. It's been said around here before, but bears repeating.

Since I spend most of my time in the studio and use modeled amps, I almost rely on the buzzing from my guitars to add a touch of realism. That's how you know it's LOUD.

[toneless]

Sorry everyone, I was extremely tired when I wrote my first post, so if I sounded incoherent, that was why. Not that I'll be much better right now, considering it's 12 my time, and I'm tired as you can imagine. Anyway, I've been busy, but I finally got around to taking some photos.

Here are some of them:

www.fileden.com/files/2006/5/25/36507/Untitled-7.jpg

That photo shows the weird ground wire thing I did, in the QTB mod, the wire going from the volume pot to the guitar body is omitted. I just decided to screw it on there in case the shielding suddenly lost contact with the pickguard somehow.

www.fileden.com/files/2006/5/25/36507/Untitled-6.jpg

Just the disconnected ground wire from the trem cavity.

www.fileden.com/files/2006/5/25/36507/Untitled-4.jpg

Blurry pic of the electronics.

www.fileden.com/files/2006/5/25/36507/Untitled-3.jpg

Slightly better pic of the electronics:

www.fileden.com/files/2006/5/25/36507/Untitled-2.jpg

Another blurry pic of the electronics (yeah I know, the camera sucks).

www.fileden.com/files/2006/5/25/36507/Untitled-1.jpg

Wide-view shot of the exposed body cavity and entire pickguard assembly.



When I said I modified the tone controls, I essentially did a modified version of this:

www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=tone_f_bp

The end result being more like this:

www.fileden.com/files/2006/5/25/36507/Tone.jpg

Anyway, later I'll come back with sound clips for this I guess. But to me, I just don't hear a difference since the mod. The two and four positions are pretty quiet (as they've always been), but other than that, the other positions just hum like no tomorrow.

Anyway, other then that extra ground wire and the tone control mod, everything is stock. Also, I just thought I'd throw out there that the guitar is a 2004 Mexican Made Strat, not that I'm sure that helps you all at all.

Anyway, thank you for your responses, I'm going to bed before my tuyp8ng on teh cumppppppputer geos to shitefssssssllllllllllllllllllllllssd88eekkkddd dfiiiiiiiiiiiiiiughaaaaaap

*falls asleep on keyboard*

[D2o]

Funny post, toneless!

And quite fortunate for us that your nose happened to land on the "post reply" button as you dozed off and face-planted into the keyboard.

Okay - I see what you've done with the bridge ground. I see that there is, more or less, a direct wire connection - which is good. I still wouldn't do it that way, as it's overkill and may introduce unwanted results ... I mean, how much better a connection can you get than soldering the wire to the pot case?

Your pickguard shielding should not lose contact with the cavities for two reasons: 1) the pickguard is screwed down, and 2) you have installed the shield so that it is coming up slightly above the top of the cavity and lays over the top of body a little bit, right? All it takes is one good point of contact between the pickguard and the body to ensure electrical and magnetic continuity throughout, so you should be fine.

As for anything else ... say, how come the (smaller sized) aerial view of the guitar looks so clear and the rest of the huge pics don't? The big ones took forever to download, and I was twitching in anticipation of the expected wicked awesome pics. I understand though ... not all cameras are created equal.

I wonder if you can try again, backing off a bit and using a zoom function if you have it ... do what you did with aerial view, from a bit of a distance, with zoom and with some good light in there or something, 'cause I am having a hard time making stuff out. Draw a diagram of your wiring using MS Paint if you have to.

It looks like you have a wire running to the middle lug of your outermost tone pot - is that correct? If so, it doesn't jive with the SD diagram. I'm not quite clear on what you're going for with that, but I am assuming that the changes to the tone wiring that you mentioned are that you are trying to change the location of the two tones ...

Bottom line, I can't really tell all of what's going on in there ... but if everything is working as you desire it to, your modified wiring is possibly okay.

As for the hum, I don't know yet ... it "looks" okay. Even if you are playing in an electromagnetically "noisy" environment, shielding should help more than you are indicating it is.

If someone else here can diagnose it using your pics, great. Otherwise, try to get some clearer images if you can - sorry to send you back to do that.

Don't do anything to the wiring just yet.

Oh, and does the hum diminish when you touch anything metal?

D2o

[toneless]

Last minute post before I go to bed for today

Here's a diagram of the wiring, excluding anything past the jack and the funky ground wire going to the trem cavity:

www.fileden.com/files/2006/5/25/36507/Tone2.jpg

Hope this helps.

And when it was put back together, touching it didn't heal the noise, although switching two pickups on at once did.

[D2o]

Sept 12, 2008 22:41:16 GMT -5 toneless said:

Last minute post before I go to bed for today

Here's a diagram of the wiring, excluding anything past the jack and the funky ground wire going to the trem cavity:

www.fileden.com/files/2006/5/25/36507/Tone2.jpg

Hope this helps.

And when it was put back together, touching it didn't heal the noise, although switching two pickups on at once did.

Hi Toneless,

Thanks for the diagram (I see it's slightly different from the one you posted before).

If touching metal (strings, etc.) does not affect hum, it's not sounding like a ground issue ... which is where I was going. The reduction in hum when you select two pickups is expected and normal; you've created a humbucker is all, so it's not revealing anything.

If the hum is pretty much the same as it was "pre-shielding", I guess the shielding just isn't working for you. I have no good idea why

... your shielding looks good, and I can tell you that - while this is not what we're aiming for - even a shielding job that is neither electrically nor magnetically continuous should offer some reduction in hum. I know this because one time I needed my guitar back together before I could complete the shield, and the poor shielding job still reduced hum noticeably until I was able to go back in and complete the job.

I would feel much more comfortable in discussing this on either a full QTB modded guitar (which i am guessing you aren't going to be jumping at, is that a fair statement?) or perfectly stock wiring in your shielded strat (which you might just go for).

I admit that wiring re-configuration is not my strong suit, but exactly what benefit it is that you're going for with the modified wiring is not jumping out at me. Can you describe what you think you are gaining here? And if you're not sure, would you consider wiring it back to stock?

I'd like to hope we'll get this sorted out ... we'll see.

D2o

[toneless]

Sorry, long time no post.

Anyway, I recant my earlier statement about touching the strings and how it affects the noise. The guitar did quiet down *slightly* (and by "slightly" I mean "barely noticeable"). Anyway, about stock, I'm pulling the guitar apart as we speak. I'll have to leave the ground wire non-stock though (I don't have a wire to replace it) and just use the QTB style ground. I will of course desolder the half still stuck to the volume pot as well. As for the tone mod, I'll undo that as well, although I'm not sure how it could be affecting anything.

[D2o]

Sorry, long time no post.

Anyway, I recant my earlier statement about touching the strings and how it affects the noise. The guitar did quiet down *slightly* (and by "slightly" I mean "barely noticeable"). Anyway, about stock, I'm pulling the guitar apart as we speak. I'll have to leave the ground wire non-stock though (I don't have a wire to replace it) and just use the QTB style ground.

Just to clarify: by QTB style ground while using stock wiring, do you mean that you will let the shield (only) do the work that the wire between the pots was doing, or do you mean that you will use the star ground?

If you mean that you will use the star ground - and I apologize if I have already asked you this: Have you insulated the star ground (wrapped it in tape, for example) so that it does not come into contact with the shield?

As for the tone mod, I'll undo that as well, although I'm not sure how it could be affecting anything.

Yes, I would say you are right to question me on that - it's my shortcoming ... not yours.

D2o

[toneless]

Sept 19, 2008 11:11:33 GMT -5 D2o said:

Just to clarify: by QTB style ground while using stock wiring, do you mean that you will let the shield (only) do the work that the wire between the pots was doing, or do you mean that you will use the star ground?

No I will not be using star grounding. The only thing "non-stock" will be the shielding itself, and the ground wire going to the trem cavity from said shielding. I'm going to remove the half of it that's connected to the volume pot still like it says in the QTB directions. Anyway, it might take a while, I'm running low on fuel for the soldering iron and I'll probably run out before all of this is done (Damn it I wish I had and electric soldering iron!). Will post back with more.

[D2o]

Okay, just remember that without the QTB star grounding, you're really just shielding a stock guitar.

D2o

P.S. Hope you don't run out of gas.

[toneless413]

Well, I was going to take my guitar apart and do the wiring changes, then life came along and preoccupied my time. I have yet to make the changes, but I did pot the pickups while helping a friend out in fixing her 1960's Teisco. Now its open in front of me and I'm going to put it back to stock wiring, I already took off the funky ground wire thing I had on the volume pot.

[D2o]

Oct 20, 2008 18:38:22 GMT -5 toneless413 said:

Well, I was going to take my guitar apart and do the wiring changes, then life came along and preoccupied my time. I have yet to make the changes, but I did pot the pickups while helping a friend out in fixing her 1960's Teisco. Now its open in front of me and I'm going to put it back to stock wiring, I already took off the funky ground wire thing I had on the volume pot.

Hey toneless - welcome back!

Say, did you lose your old password? If you can find it, it's better to come back as the ole toneless of yestermonth.

Hey ... you got older too! How do I know this is the real toneless?

Either way, keep us posted.

D2o

[mr_sooty]

Sept 9, 2008 19:37:21 GMT -5 ChrisK said:

Your guitar picks up noise from a cell phone?

Cellphone's can definitely cause noise through a guitar, even a sheilded one, even if the phone is on standby (not when it's off though of course). I've found it depends on the phone, my old cell phone caused much more noise than my new one.

I was playing an event once and at sound check was finding i was getting this crazy, hideous squeal coming through my amp. This was with my old '57 reissue Strat that had the full QTB mod, and was otherwise reasonably quiet.

I found that when I crouched down (to check whther the problem was coming from my pedal board) that the squeal disappeared. I soon realised that this was because it was being caused by the cell pone I had in the coin pocket of my jeans. As I crouched down the guitar moved away from my hip and the noise went away.

I find my new phone doesn't cause this problem to the same degree, but even with my new noiseless Dimarzio's loaded in my thoroughly sheilded 08 US Std Strat, there is still a faintly audible noise created by my new phone if I hold it close to the pickups.

Also, I still get some noise from a laptop. Computers just wreck havoc with guitars. I get laptop noise even with humbuckers, and as I say, the hum cancelling single coils in my new strat. This new strat is really dead quiet in most situations, but it will still pickup some noise from a laptop.

The sheilding, QTB thing is really about bringing your noisy single coil equipped hummer into line with quieter humbucker equipped guitars. It's not going to make it totally silent. But it should be helping.

[toneless413]

Argh! Life and that s***ty soldering iron again. I attempted to do the job, but the soldering iron was too underpowered for all the solder joint's on the back of the pots and the like. So I guess I'll have to save up for a better one. I'm going with a nice electric one that has temperature control. Anyone that has recommendations on a soldering iron is welcome to post them

Edit: And I'm the same toneless from yesteryear, just lost my password *doh*. Anyway, I never put in my actual info into my web accounts, just an old habit. Don't trust the internet...

[D2o]

Argh! Life and that s***ty soldering iron again. I attempted to do the job, but the soldering iron was too underpowered for all the solder joint's on the back of the pots and the like. So I guess I'll have to save up for a better one. I'm going with a nice electric one that has temperature control. Anyone that has recommendations on a soldering iron is welcome to post them

$10 for a 35 watt iron should do it. More $ for a fancier iron should do it even better.

I have a 25 watt which does most of it just fine, and when I have a particularly troublesome glob on the back of a pot I bring out the blow torch and get a very low flame going, well away from the guitar and anything flammable, and I use the flame to heat the soldering iron tip for 1-2 seconds ... then it's like a hot knife through butter.

With 35 watts I likely would not need to do that. Say, $10 for a 35 watt iron ... ya think maybe I should get one? Well, I get by with the other so I just haven't remembered to get around to it.

Also, are you making sure that your iron is being kept in optimal working order? Are you letting it heat up properly, and keeping the tip clean, and tinned? If you are not, you may be surprised what a difference it makes.

Edit: And I'm the same toneless from yesteryear, just lost my password *doh*. Anyway, I never put in my actual info into my web accounts, just an old habit. Don't trust the internet...

So long as we're being honest, my name may not really be D2o.

D2o

[ChrisK]

I should have been much more clear. The issue that I had with cell phones causing noise related to the RF frequency range in use (800'ish Mhz in the U.S.). Much of the noise discussed below will be based on interference cause by much lower frequencies.

Cell-phone's can definitely cause noise through a guitar, even a shielded one, even if the phone is on standby (not when it's off though of course). I've found it depends on the phone, my old cell phone caused much more noise than my new one.

I would expect the older designs to be noisier since they consumed more power. This may well be emitted switching power supply noise.

I found that when I crouched down (to check whether the problem was coming from my pedal board) that the squeal disappeared. I soon realised that this was because it was being caused by the cell pone I had in the coin pocket of my jeans. As I crouched down the guitar moved away from my hip and the noise went away.

Yep, power supply noise and likely not high frequency RF (unless your amp and ears handle those frequencies).

BTW, that isn't (wasn't) a coin pocket on the original jeans but a watch pocket (those things in use before we started depending on our cell phones to keep time for us).

I find my new phone doesn't cause this problem to the same degree, but even with my new noiseless Dimarzio's loaded in my thoroughly shielded 08 US Std Strat, there is still a faintly audible noise created by my new phone if I hold it close to the pickups.

Yep, newer designs (much higher frequency switching power supplies) and much lower operating currents for digital radios.

Also, I still get some noise from a laptop. Computers just wreck havoc with guitars. I get laptop noise even with humbuckers, and as I say, the hum canceling single coils in my new strat. This new strat is really dead quiet in most situations, but it will still pickup some noise from a laptop.

Yep, again power supply noise. The largest consumer of power in a laptop is the LCD back lighting (and its power supply is a Royer oscillator - a variable switching frequency power switcher).

CCFL back lighting operates at 800 to 1,200 VAC at 8 to 12 Khz.

;)HINT: Turn your back lighting all the way down whenever not in use or hibernate. The CCFL lamps have a half-life of 8,000 to 20,000 hours (at the end of which they'll be half as bright).

The shielding, QTB thing is really about bringing your noisy single coil equipped hummer into line with quieter humbucker equipped guitars. It's not going to make it totally silent. But it should be helping.

Absolutely! Shielding is not infinite.

I had a customer that ran 24 VAC power (not 240 VAC) and a RS485 differential comms network in the same conduit. He was upset that he saw about 500 mVAC of 60 Hz noise on the comms lines. He was using a shielded twisted pair for the comms that had about a 99% shielding rating.

Gee, math!


Now, if your guitar and amp start picking up/receiving cellular calls........seek counseling.

[ChrisK]

and I use the flame to heat the soldering iron tip for 1-2 seconds ...

Hmmm, I hope that the electrical windings in the iron have a high enough flame rating.......


One can get soldering irons with interchangeable/replaceable tips. I use a finer tip for wiring and a larger tip with a lot more mass for pot shells.

I've also found that clean surfaces are best. I often scratch the pot shell with the tip of an X-acto knife or steel wool and then solder. I also will attach wires to the ground terminal on a pot and then connect that terminal to the shell with a 1/2" solid jumper wire rather than (trying) to solder a bunch of wires to the shell.

A well-tinned AND clean iron tip is vital. Use a small damp (not soaked) sponge to wipe the tip lightly prior to each soldering operation.

[D2o]

and I use the flame to heat the soldering iron tip for 1-2 seconds ...

Hmmm, I hope that the electrical windings in the iron have a high enough flame rating.......

Chris, that's a good point.

While I purposely keep the flame really low, and the exposure relatively short in duration, I also admit that I kinda/sorta wouldn't mind killing it so I'll finally remember to get a proper new 35 watt one out of necessity.

So far, despite my efforts, I have not managed to "done her in".

D2o

(quoting a certain Ms. Doolittle)

[ChrisK]

Well, "fire" away then.










Just remember, someone's always the fuse....................

[toneless413]

Whoa, where did I go! I know I haven't posted in forever on this thread, but life unfortunately intervened and made me extremely busy as of late. Anyway, now that I've finished my senior year of high school and have taken care of *most* things college wise, I have finally gained some free time to take apart my strat and work on it.

Anyway when I left last I didn't have a good soldering iron. Well, I'm glad to say that I've gotten a nice electric, 40 Watt pencil type iron from radio shack, and while the pots still are hard to work with, it does the job fairly well ;D.

As a result of the new iron, I've been able to change the wiring on my guitar some more, I didn't put it back to stock, but I did get rid of my tone control changes, those at least are stock now. However, I also pulled out the ground loops created by the wires connecting the backs of the pots. Those are gone now. Also, the tone capacitor is grounded to the back of my volume pot now, which is working as my "star grounding" point.

After this though I'm still seeing no reduction in noise, the sheilding acts like it isn't even there. I think that there might be a possibility that the shielding is somehow mixing into the signal, but I don't know how, a short somewhere?

I have more looking over to do, more to come.

~Toneless413

[newey]

Welcome back, Toneless!

We're still waiting on some photos of the innards, that may help diagnose some issues.

[toneless413]

Hmmm, I just did some sound tests, and the guitar actually sounds pretty quiet now. Still pretty loud when you put it right up against something that would cause noise, but nearly silent when about 3 feet away from said noise-makers. Maybe that wiring change up got rid of a short or something, but I'm liking how it sounds right now, definitely better.

I'm not sure how great of a test this is but I notice that I myself cause some noise and I can ground myself using the strings, well, it theory. Before the difference was *barely* noticeable, or non-existant (probably because something or other was wrong in my guitar), but now it seems to work.

Because the strings are connected to ground by the shielding, I'm going to abuse the theory of transitive property to say that the shielding must finally be working now, because I can actually hear things quiet down considerably when I touch the strings.

Maybe it was all them ground loops that were causing problems after all?

Anyway, I'm just glad things seem to be working now, I can't wait to sow this guitar up and plug it into my Valvetrain 105 (see modern day replica of 1960's Fender Champ, 5F1 Circuit). I also got some new 12au7 preamp tubes to mess around with today, so I'm doubly happy today ;D

Enough talking on my part then, I got a guitar to put back together and play