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Post by newey on Jan 10, 2016 10:41:24 GMT -5
Let's talk wire colors, instead of "positive" and "negative". In RT's diagram, the black wires are the "negative" ones from the pickups, while the dummy coil colors really don't matter, one goes to one pickup and one goes to the other. To wire it just to the neck pickup alone will require re-doing the wiring to the right side of the selector switch.
You would wire the neck pickup's black wire to either end of the dummy coil, then wire the other end to the furthest-right lug of the switch (oriented as shown on the diagram). The middle pickup's black wire then moves over to the left one lug, to lug #7 as shown.
Note that, done this way, you will have the dummy coil on the neck in position 4 (i.e., N + M), but not on the middle pickup. In RT's scheme, since the N and M will hum-cancel at position 4 (assuming a RWRP middle), the dummy coil was shorted and inactive at that position. I'm not sure what you'll get with one pickup having the dummy coil at that position. But at least you can test for hum reduction in position 5, which I gather is the objective, to see if the dummy is helping at all.
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Post by rabidgerry on Jan 10, 2016 11:43:04 GMT -5
Yeah I just now want to test and see if there is actual hum reduction to begin with.
One thing I did not do with RT's diagram is take the right common tab and wire it to the chassis of the selector witch. Instead I wired it to the back of the volume pot.
I have now changed this and copied exactly the RT diagram, all except one wire that RT had going from the ground Tab at the side of the selector switch to the back of the volume pot. Reason why is because I have shielded the back of the pickguard and the selector is screwed down to the shielding therefore mechanically attaching the chassis to ground so no reason to wire another wire from the chassis to the back of the volume pot. Make sense?
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Post by newey on Jan 11, 2016 0:19:52 GMT -5
I'll quote, or at least paraphase, the late ChrisK on this subject. Shielding is for shielding, not for carrying signal. Don't rely on a bit of foil, or pressure of contact to that foil, for any signal-carrying portion of the circuitry.
It may not matter, but it's one of those "best practices" things. IOW, run the wire over there.
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Post by rabidgerry on Jan 11, 2016 4:50:09 GMT -5
I'll quote, or at least paraphase, the late ChrisK on this subject. Shielding is for shielding, not for carrying signal. Don't rely on a bit of foil, or pressure of contact to that foil, for any signal-carrying portion of the circuitry. It may not matter, but it's one of those "best practices" things. IOW, run the wire over there. Surely it doesn't matter since at one stage I already had the right common go straight to the back of the pot which essentially is doing the same thing as wiring to the chassis of the selector, and then wiring that chassis tab to the back of the pot is not? The reason I do not have my selector earthed to the back of the pot is because it is screwed onto the shielding. It's definitley not the cause of the excessive noise I am getting with the dummy. I got the idea for not having things earthed twice from "Taming the beast". Made sense to me to avoid ground loops. It's time to just wire it in series with the neck as a test. It's clearly not working in parallel attached to the selector switch. What ever reason that may be I do not know. The article I read suggests 50%-80% in regards to resistance matching. My dummy is 5.6k and the pickup is 6.5k so this should be perfect and I should (at the very least) hear some reduction in noise. www.frettech.com/frettech/dummy/index.htmlIf the worst comes to worst I can implement a switch to turn the coil on or off like so, mind you I didn't want to add the extra switch.  |
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Post by newey on Jan 11, 2016 6:09:03 GMT -5
RT's diagram has the dummy coil in series, not parallel. Note how, on the right-hand side of the switch, the neck black goes to lug #7, while the mid goes to #8 (the opposite from what we'd expect). The dummy is wired between 7 and 8. If you trace the signal flow, you'll see the coil is in series. When in position 5 (i.e., neck only, the neck + is connected to the output via the left side of the switch; the black goes to lug #7, through the dummy coil to lug 8, then to ground via the left-side commons. The mid pup does just the opposite in position 3. In position 4 (N + M), both ends of the dummy coil short together and you have N + M in parallel. I thought RT's idea there was particularly brilliant, I'd never seen anything of the sort done before with a std 5-way switch. I immediately thought that technique (in at #7, out at #8)could be used for other things, like wiring one coil of a HB to the switch that way, so as to get a full HB in position 1 and a split-coil in parallel with the mid pup at position 2. Earthing the body of the selector is unnecessary with a shielded chassis. The earth connection there is just for shielding. But, the way RT has it, there's signal to there, so properly it ought to be hard-wired to the other grounding point(s). Assuming the Vol pot is, in turn, grounded to the output, those two things are equivalent. This is a signal-carrying connection. If you're using the shielding to connect the Vol pot to ground, then you have the same issue as I mentioned above, just moved to a different location. Ground loops may or may not be a significant contributor to noise, that has been an oft-debated topic around here. But loops in the shielding side of the circuit can't cause noise to be introduced into the signal since (ideally) they're not carrying signal. If you think about it, your shielding is, in essence, just one big "ground loop". Whether you daisy-chain the signal grounds or use a "star-grounding" technique, the preferred way to do this is to have all the signal grounds run separately from the shielding. Again, it may not matter, but it's a best practice. A (properly) soldered wire can be counted on, contact between two components cannot. I'm sure we've all experienced a pot or switch loosening up with use; no big deal if it's only connecting shielding points.  |
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Post by rabidgerry on Jan 11, 2016 10:06:39 GMT -5
Ahhh yes I see!!
Ok so it is in series. And I understand the flow. And the only thing I am lacking compared to the diagram is one wire going from the earth lug on the selector switch going to the back of the pot (and as I said it's because the selector switch in my wiring isd already going to be gronded once scratchplate is screwed down). So say I wire the one wire I am missing (earth lug to the back of the pot), will my problem be solved?
I doubt this but I'll do it anyways.
Failing this I shal try the one pickup only approach as a test.
Could there be something wrong with the pickup I'm using as a dummy? It tested alright before I put it in. And it tested ok whilst in. I'm totally mistified now as to why this will not work.
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Post by rabidgerry on Jan 20, 2016 19:09:06 GMT -5
Ok so I wired the pickup in series with the neck pickup only.
Results, no noise reduction at all. This seems very weird to me. Anyone any ideas? It must be the pickup I'm using for the dummy coil, but what's wrong? I tested it and it works giving 5.64k on multimetre.
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Post by rabidgerry on Jan 21, 2016 7:56:33 GMT -5
I have not tried this but it appears my problem is to do with postioning of the dummy coil.
I have not heard it mentioned here (I may have missed it) but according to other instructions I have read on dummy coils, the positioning is crucial.
So basically the dummy coil needs to be facing the same was as the pickup it's linked with. Well my dc has been sideways and all sorts of postions purely to try and get it under the pickguard! I managed to make a bit of room under there so it now fits better, so I'll turn it up poles facing to the floor of the pick guard and close the guitar up and see what happens.
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Post by newey on Jan 22, 2016 6:00:16 GMT -5
Way back at the beginning of ths thread, Gunther discusses the issue of positioning, He apparently played around quite a bit with that.
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Post by rabidgerry on Jan 22, 2016 12:55:13 GMT -5
I found a good position. Contrary to what I read, the pickup I am using seems to cancel some noise when pointing the opposite way from the magnetic pickups. I.E so you have your pickups facing the strings, well inside if I position the dummy where the poles actually face toward the back side of the guitar as opposed to the strings I get cancelation.
Ok so having it this was I can't close the pickguard up. So operation make space is in effect. On top of this I shall revert the wiring to reflect RT's diagram. Fingers crossed! I have also ordered a cheapie pickup with the same resistance the actual magnetic pups so this could be even better!
When I tested earlier I was using a highish gain setting that I know is quiet with a humbucker.
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Post by JohnH on Jan 22, 2016 14:30:19 GMT -5
You have to have the axis through the poles/coil of the dummy the same as the main pu's, ie perpendicular to the face of the pg. But if, to make this work with cancellation, the dummy needs to be upside down, then you can swap its wires and place it right way up.
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Post by perfboardpatcher on Jan 23, 2016 5:01:15 GMT -5
From personal experience I know that I don't have a hum problem in my home. When I switch from humbucker to split coil I don't hear nothing. I get noise when my circuitry is in the open and not in its Faraday's cage, when I hold my unearthed hand close above the pickup or when my volume pot is at half resistance position but it's not the noise that can be solved with anti-noise. Where's the hum when you need it!  So my question is, what procedure do the moderators recommend to me that would conclusively prove that my humbucker is hum-canceling and my split coil is not? |
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Post by newey on Jan 23, 2016 8:11:35 GMT -5
Why is there a concern if it's quiet? I guess the answer to the question would be to take the guitar to another location where there is more electrical noise. . .
However, the bit about getting noise at half volume is strange. Sounds like a faulty pot.
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Post by perfboardpatcher on Jan 23, 2016 12:10:09 GMT -5
Why is there a concern if it's quiet? I guess the answer to the question would be to take the guitar to another location where there is more electrical noise. . . However, the bit about getting noise at half volume is strange. Sounds like a faulty pot. I have no problems with my guitars whatsoever. I was just following the topic. I thought my question could speed things up a bit. If it's too much trouble to answer my question, then don't! No problem  |
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Post by newey on Jan 23, 2016 13:00:55 GMT -5
Well, the one in your avatar seems to have some issues! Seriously, I thought I did answer your question. If there's "no noise" in one location, then there's no way to establish if one pickup is noisier than the other.. Now, of course, we can debate the subjective definition of "no noise". How about at high gain settings? |
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Post by sumgai on Jan 23, 2016 13:36:11 GMT -5
Paul,
Sometimes you think really outside of the box, don't you....
newey,
pfp (Paul) is trying to come up with a way to 'force' hum to show up on demand, for testing purposes only. greekdude's home notwithstanding, most home environments are pretty low on the AmountOfHum scale. Certainly there are exceptions, but for the most part....
All,
My first thought would be to use an older soldering gun, not an iron as we usually recommend* here in The NutzHouse. Any wattage will do, as these contraptions are totally unshielded in any way, thus they throw off a lot of hum. Bring one within several inches of any (working) pickup, and you'll see what I mean. Just be aware that these monsters will overcome the best of shielding (and other schemes) if you get them close enough.
My next thought would be to use a fluorescent light. Many such lights, of all sizes and descriptions, are good sources of hum. Certainly you can get more expensive ones that don't hum, but for the most part, they'll do just fine for what we want. If your home has no such thing (few do), then you can buy one for a reasonable cost at most places that sell lighting of any kind. If nothing else, you can buy a small (short) shop light, or an even smaller one that's meant to go under kitchen cabinets. (But to be fair to the lighting industry, most kitchen lights are now coming as LED units, so a fluorescent version may be hard to find; I dunno.) I have one of these, and it works just as I've described, but it's not as portable.
If you have to leave the house to find a noisy environment, and if you're old enough, head down the local watering hole. The neon lights in there will knock you out, they're so noisy! 
HTH
sumgai
* There is one reason to use a gun on a guitar, and that is to solder several ground leads to the back of a pot, quickly. This would be the only time I'd recommend the use of a 100 watt gun inside of a guitar, to quickly heat the back of a pot in order to melt the solder as soon as possible, then to remove the heat immediately afterwards. This near-instant heating of the pot's metal shell, and the quick removal of that heat, will greatly enhance the chances of your pot surviving the ordeal - even a little heat (from a low-wattage iron) will spread to the innards, given enough time, and that will kill your pot, no doubt about it. This is why I have a 40 watt iron, for pot-soldering jobs, and a 25 watt iron, for everything else. (Although, I also have a 100/250 watt gun for soldering ground joints inside the chassis of an amplifier. That's a lot of metal to try and heat up with only a 40-watter!) |
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Post by rabidgerry on Jan 23, 2016 15:02:38 GMT -5
You have to have the axis through the poles/coil of the dummy the same as the main pu's, ie perpendicular to the face of the pg. But if, to make this work with cancellation, the dummy needs to be upside down, then you can swap its wires and place it right way up. so what you mean is if I swapped the wires around I would have to turn the pickup the other way around again? Currently I have followed RT's diagram, so this is the way I have everything wired to the 5 way switch. And in order to get noise cancelation I have to have the dummy upside down, or to put it another way have it's top face, face the bottom of the guitar cavity as opposed to facing the underside of pickguard. It's pretty quiet. But not as much as a humbucker. As I mentioned before though I might have to get a better candidate as my dummy. The results I am pleased with. The circumstances of which I am testing the effectiveness of the dummy are always a regular hi gain setting I use. This includes noise reduction. If I switch the noise reduction off even the humbucker is noisy, so my test involves the effectiveness of the dummy under my usual playing set up and settings. To give a better understanding of the level of noise I was getting with single coils I must mention that without the dummy coil, and without hi gain my singles where quiet to begin with. So the whole aim for me was to try get single coils as quiet as my humbucker under hi gain settings (for which a noise reduction devise is also required). If I played clean stuff both singles and humbucker are quiet unless right next to an amp. However introducing gain would make both get noisier as you would expect. Hence dialling in enough NR to quieten the noise experienced with the humbucker. However this would not be enough to get rid of the single coil noise. In fact the noise from the singles under hi gain was/is really bad and you would have to use a stupid amount of NR to get rid. But with this high a NR setting you tone is sucked to pieces and rendered awful/useless. So the addition of a dummy is basically to help lower the noise floor of single coil pickups. I am pleased I decided to try it out. I definitely aim to get it a little more quiet although I could definitely live with the level of noise I get now. I did not detect any reduction in treble myself. I can't say for sure, could be my imagination, but it might have sounded different in some way but I don't know what exactly. And this difference is a lot to my liking. I really, really liked it in fact. |
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Post by perfboardpatcher on Jan 25, 2016 14:51:49 GMT -5
Well, the one in your avatar seems to have some issues! Seriously, I thought I did answer your question. If there's "no noise" in one location, then there's no way to establish if one pickup is noisier than the other.. Now, of course, we can debate the subjective definition of "no noise". How about at high gain settings? Just a picture, newey! I don't have the luxury problem of owning the original Red Special! Concerning the potmeter, it's the hiss because of the impedance "seen" by the amp. Only to be noticed with a fair amount of gain while not touching the strings but it's still more noticeable than the hum. Perhaps the hiss is caused by the inferior shielding of the stereo cable I use. I have an impedance buffer built in and phantom power for my sustainers. In active mode the guitar is dead quiet. |
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Post by perfboardpatcher on Jan 25, 2016 15:16:40 GMT -5
Paul,
Sometimes you think really outside of the box, don't you....
newey,
pfp (Paul) is trying to come up with a way to 'force' hum to show up on demand, for testing purposes only. greekdude's home notwithstanding, most home environments are pretty low on the AmountOfHum scale. Certainly there are exceptions, but for the most part....
All,
My first thought would be to use an older soldering gun, not an iron as we usually recommend* here in The NutzHouse. Any wattage will do, as these contraptions are totally unshielded in any way, thus they throw off a lot of hum. Bring one within several inches of any (working) pickup, and you'll see what I mean. Just be aware that these monsters will overcome the best of shielding (and other schemes) if you get them close enough.
My next thought would be to use a fluorescent light. Many such lights, of all sizes and descriptions, are good sources of hum. Certainly you can get more expensive ones that don't hum, but for the most part, they'll do just fine for what we want. If your home has no such thing (few do), then you can buy one for a reasonable cost at most places that sell lighting of any kind. If nothing else, you can buy a small (short) shop light, or an even smaller one that's meant to go under kitchen cabinets. (But to be fair to the lighting industry, most kitchen lights are now coming as LED units, so a fluorescent version may be hard to find; I dunno.) I have one of these, and it works just as I've described, but it's not as portable.
If you have to leave the house to find a noisy environment, and if you're old enough, head down the local watering hole. The neon lights in there will knock you out, they're so noisy!
HTH
sumgai
* There is one reason to use a gun on a guitar, and that is to solder several ground leads to the back of a pot, quickly. This would be the only time I'd recommend the use of a 100 watt gun inside of a guitar, to quickly heat the back of a pot in order to melt the solder as soon as possible, then to remove the heat immediately afterwards. This near-instant heating of the pot's metal shell, and the quick removal of that heat, will greatly enhance the chances of your pot surviving the ordeal - even a little heat (from a low-wattage iron) will spread to the innards, given enough time, and that will kill your pot, no doubt about it. This is why I have a 40 watt iron, for pot-soldering jobs, and a 25 watt iron, for everything else. (Although, I also have a 100/250 watt gun for soldering ground joints inside the chassis of an amplifier. That's a lot of metal to try and heat up with only a 40-watter!) This is what I mean, sumgai! Thanks for the detailed information. It's not so much thinking outside the box - not this time. It's more a case of having enough hum to produce a readout on my oscilloscope and have the hum available on demand. I think I go for the solder gun, gonna see where I left mine. Although I don't have any single coils at all I like to do some experiments. BTW has anyone tried to use (PAF) humbucker coils for their dummy coil projects? They are easier to dismantle and when you do you're left with a coil that's as small as you can get. And it's easy to attach to the guitar's scratchplate with double side tape. And you can stack 2 of those coils on top of each other and use a resistor to shunt one of the coils and try to match anti-hum with hum. I don't see no other way to get it exactly right. What are the chances of finding an unwaxed high output coil for cheap that can be unwound? |
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Post by ashcatlt on Jan 25, 2016 17:55:18 GMT -5
An electric screwdriver or toothbrush will also give you a consistent noise to test humbucking with. It's not necessarily the same frequency profile as the 60Hz noise we normally have to worry about, but it'll give you the idea. I tried once to use one of these as a consistent source to test relative output between series/parallel/split. Didn't work for that. |
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Post by JohnH on Jan 26, 2016 4:34:18 GMT -5
I suspect that a 'test hum' arrangement is going to get very confusing unless it is a very even source - ie local hum producing gadgets will not put the same flux to each coil. eg, in some of my humcancelling combos of coils, getting too close to the amp makes it go very unbalanced.
btw - been away in India for a couple of weeks, in uk right now. - great trip!
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Post by perfboardpatcher on Jan 30, 2016 3:16:59 GMT -5
Now I think about it, my signal generator has a 50ohms output. If I make a couple of air coils and stack them on top of my pickups and dummy coils.....
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