petitjean
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Post by petitjean on Mar 26, 2009 11:13:45 GMT -5
Hi all,
In my Epiphone Les Paul I have a Humbucker from Hell (neck) and a Air Zone (bridge). I very much like the sound of both. HFH: almost acoustic, AZ: ideal for sustained overdrive. But I'd really like to have a sound in between, also.
Problem: MASSIVE IMPEDANCE MISMATCH. It seemed a standard toggle switch wiring was not an option. Needed to lower the HFH volume to hear the AZ. The mixed sound wasn't even that nice (the sounds lay on top of each-other).
I now have a 4P3T switch. In the middle position the outer coils are wired in series. This sounds great.
But: HUMMING Since the Coils have totally different amount of turns, it's not really humbucking anymore. Or does the coil position matter that much in a normal (electrodynamic) environment?
Can you help me with these questions/ideas, please: Can i assume the both coils one Humbucker have same amount of turns??? Inner coils parallel with outer coils? (Humbucker in parallel) in series with (Humbucker in parallel)? More ideas welcome
Many thanks in advance!
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Post by newey on Mar 26, 2009 16:14:10 GMT -5
petitjean- Hello and Welcome! This puzzles me, I would have thought it would be the other way around. Presumably, the marketing folks called it a "Humbucker from Hell" for a reason. Also,I don't think you mean "impedance mismatch", you mean that the HFH has higher output than the AZ (at least, I think that's what you mean). I suspect that the problem is not a difference in the number of turns, but in your choice of coils in each humbucker. In order for the combination of the two single coils to be humbucking, one must be of opposite magnetic polarity and be reverse wound (RWRP) with respect to the other coil. Did you check for polarity before deciding which coils to use? If not, you would want to switch ONE HB from the outer to the inner coil, that should ensure that you've got a RWRP coil in the mix. Not necessarily, but again, probably not relevant either. No, usually the 2 coils in a HB are wired in series, unless you have modified them to be in parallel. Again, depends on how you wired 'em up. A std LP would normally have the coils in each HB wired in series, with the 2 HBs wired in parallel with each other. But variations abound.
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petitjean
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Post by petitjean on Mar 26, 2009 18:06:04 GMT -5
that's because it's so awesomely bright, your ears will hurt if you put it in the bridge position.
i think it really is the impedance. Output of HFH is actually lower.
I payed attention to reverse winding and all.
For a humbucker to be completely humbucking, i can only imagine that the turns have to be almost equal. What else would do the humbucking?
I saw some designs on this forum for wiring that were new to me: <1 coil> in parallel with <2 coils in series>, ect.
Somebody has any ideas in that direction? Don't really have space for a dummy coil.
Can somebody awnser the question about the picking up of Hum and the position of the coils?
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Post by newey on Mar 26, 2009 19:14:00 GMT -5
Ok. if you checked the coils and one is RWRP, then the source of your hum lies elsewhere. I'm assuming this hum only occurs in the middle position on the toggle, as implied in your original post. Even two disparate coils will have quite a bit of hum canceling effect, even though their coils may be wound unequally, as long as one is RWRP with respect to the other. Certainly, there would be a theoretical lower limit in number of windings, below which hum cancellation would be negligible. But the difference between even the "hottest" and the "coolest" usable coils isn't a large enough fraction of the total windings to make much difference. Please post either some photos of the innards, or a copy of the diagram you used to wire it, or both. Further diagnosis will be needed. If, by "position of the coils", you mean whether one chooses to join an inner coil or an outer coil with one or the other from the other pickup, it doesn't matter much for purposes of hum cancellation- so long as one of the pair is RWRP. You could do exactly that with the switch you have- as well as a few other possibilities. I assume these are 4-conductor HBs? I'll see if I can find such a scheme for an LP around, I know it's here somewhere, just have to find it. EDIT: Just so we're clear, you said: I mean that you must not only make sure which way the coils are wired with respect to each other, you must also check for magnetic polarity. This is done either by an attraction/repulsion test if the pups are outside of the guitar, or using the "screwdriver pull-off" method if they're mounted and wired already.
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petitjean
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Post by petitjean on Mar 26, 2009 21:12:20 GMT -5
Here is my wiring diagram. The whole discussion is about the middle setting.Maybe the problem is "hanging" coils picking up hum. But, since those loops aren't closed, i can't imagine a great effect Upper 2 coils are Air Zone Bottom 2 coils are Humbucker from Hell Coils in middle position are outer most coils on guitar Up (AZ - bridge) sounds middly (ideal for sustained OD) Down (HfH - neck) sounds very open, round and clear For the middle position I'd like a standard Humbucker sound. I achieved this, but this diagram gives me considerable hum in the middle position. (Can be noticed even more on stage with alot of electrical equipment around me)
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Post by ChrisK on Mar 26, 2009 21:32:57 GMT -5
Good, this can be of use. The outer bridge coil is likely the weakest signal sensing placement. But, you do like it. Well, as newey sez "a little bit of hum canceling winding goes a long way." As opposed to what; a quantum electrodynamic environment? While the bridge coils do have differing sensing effect, the neck coils are ratio-metrically much closer together and matter less. If you have substantial humming when one coil from each is selected, do not assume that the coils that you have selected are RWRP. For hum cancellation, the two selected coils MUST have opposite magnetic polarity. The winding polarity can be easily reversed with a four-wire humbucker. Do not assume that this is the case. The outside coils are likely the screw coils and very likely have the SAME magnetic polarity. You may need to choose the screw coil on one pickup and the slug coil on the other. Either that or you will need to reverse one of the pickup's magnets. And, the impedance impedes the flow of current, usually in the form of a pickup's self-filtering frequency response. Impedance is a complex (as in the complex plane) function of the inductive reactance, capacitive reactance, and resistance of the pickup in conjunction with all interconnected external passive components. The voltage generating level of the pickup is what determines its output level, as limited by its impedance driving the impedance of the interconnected external passive components.
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Post by ashcatlt on Mar 26, 2009 23:21:20 GMT -5
I'm a little confused by the switch, but it looks to me like the middle position is one coil in series with two others in parallel.
If this is the case then you should expect to get hum. 1 + (- 1) = 0, but 1 + (-1) + 1 = 1, and 1 + (-1) + (-1) = -1. Of course, only absolute value really matters.
I'm not actually seeing any hanging hots. That would be where there is a coil connected to the hot output, but not to the ground. This coil can act to increase noise for the same reason that any other antenna works. If I understand correctly, the "ground end" of the circuit is completed via capacitance with whatever is radiating the EMI/RFI being picked up.
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petitjean
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Post by petitjean on Mar 27, 2009 11:51:33 GMT -5
In the middle position of the 4P3T switch, all the switches in the circuit diagram are also in the middle position.
So the top-left coil is in series with the bottom-right coil.
In the circuit diagram I've drawn the switch like a center lug that can connect to 3 different lugs (in reality there are 2 lugs). The lines between 2 of the 3 lugs simulate the limitation of the "real" switch. (compare to switch-layout, shown below the circuit)
Thanks guys, for trying to help me tackle this problem
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Post by ChrisK on Mar 27, 2009 18:01:24 GMT -5
I have never seen the switching logic sequence that you drew for your 4P3T switch. For C&K switches, on page G5 one can see the switching logic for the C&K 7000 4PDT ON-ON-ON (4P3T Center -ON) series mini-toggle switch from digi-key. search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CKN1139-NDFor the E-Switch 4P3T switch, on pages 113 and 114, one can see the switching logic for the 100 series 4PDT ON-ON-ON (4P3T Center -ON) series mini-toggle switch from digi-key. www.e-switch.com/pdf/100.pdfFor the NKK Switch 4P3T switch, on page 4, one can see the switching logic for the M series 4PDT ON-ON-ON (4P3T Center -ON) series mini-toggle switch from digi-key. www.nkkswitches.com/pdf/MtogglesBushing.pdfIn essence, in my 30+ years as an electrical engineer designing with mini-toggle switches, I haven't seen the contact sequence described in your drawing. While I may have not seen this one, I have seen quite a few. I use the one outlined in my Electronics Templates reference post. While your drawing is good, I can't discern which poles may have been mis-connected. Perhaps if the switch terminals were correlated to the schematic objects. I have posted what I think that the switch drawing is. I show the bottom view for the switch.
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