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Post by flateric on Aug 11, 2006 17:14:58 GMT -5
I'm building a new mahogany guitar, with a bit of PRS, a bit of Les Paul, and a bit of Parker Mojo in it. For the electrics I will go for 2 HB's with a three way selector switch, a master volume control and a master tone control with push-pull for coil tap. I've seen the SD schematics where the coil tap works on one of the pups but I want a schematic where it will be wired to both, similar to the prs McCarty wiring. Can anyone help with a suitable schematic for me? Cheers!
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Post by UnklMickey on Aug 11, 2006 17:31:41 GMT -5
Hi Flateric, i recently discussed the same thing with Ericweavers1: guitarnuts2.proboards45.com/index.cgi?action=gotopost&board=wiring&thread=1154957638&post=1155136094the drawing is a true schematic, so i'm not sure if you can translate that into a wiring diagram. also, it is using diMarzio colors (not the same a SD) unlike most of the SD coil split arrangement, this one bypasses the bottom coil, instead of shorting it. also, since they are stacked differently, on HB uses it's north coil when split, the other uses it's south. so, even when split, there will be hum-canceling when both pickups are on. the only times when you won't hum-cancel are Neck only (split) OR Bridge only (split). unk
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Post by JohnH on Aug 11, 2006 17:37:44 GMT -5
It should be simple - there must be a diagram out there. You only need one pole to do a coil cut, so a typical two pole switch either as a push/pull or a toggle can do both. But lets do it without coil shunting, since this is not necessary. Also, let the coils be configured to cancell hum in the both-pups-selected mode. If one does not turn up in a day or two Ill draw it.
John
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Post by JohnH on Aug 11, 2006 17:39:46 GMT -5
Well there you go - Unk's already done it!
John
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Post by flateric on Aug 11, 2006 17:41:22 GMT -5
Excellent, thanks for the swift reply Unk, I think I can put together something from the link to the thread you gave me. Cheers muchly I came across a SD schematic with 2 HB's, 1 vol, 1 tone, 3-way switch and 1 push/pull (on the tone pot) but I don't know if its a bypass or shunt to retain hum cancelling?
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Post by JohnH on Aug 11, 2006 18:35:38 GMT -5
flateric - if you mean this diagram: www.seymourduncan.com/support/schematics/2h_1v_1t_3w_1pp.htmlIt will work, but it is not as good as it should be, since it does not hum cancell in coil cut mode, and it shunts coils. (These two issues are not related). Unks schematic shows the right switch wiring. Shall we plagiarise that SD diagram and paint the correct wiring on it? not too hard to do John
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Post by flateric on Aug 11, 2006 18:43:36 GMT -5
If you can do that for me I will be most grateful. Tube of Smarties in the post. I presume its 'just' a case of connecting the red + whites to the correct push-pull poles in a different order?
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Post by sumgai on Aug 11, 2006 18:45:07 GMT -5
I think I see an issue here, but I could be wrong (it's been known to happen).
In order to be a true bypass, both ends of a two-pole device must be disconnected from the circuit. This requires at least a DPDT switch to accomplish. Using a SPST, as in unklmickey's diagram (in the Ericweaver1 thread) only disconnects one side of one of the coils, leaving the other side hanging. IOW, it has not been bypassed (although it has also not been shunted).
And just because I'm feeling particularly stupid today (it being Friday and all), why do some of you not like the idea of shunting a coil? Seem to me that if you eliminate any possible inclusion within the circuit, then you've accomplished the mission, no? And at that, you used only one switch pole, not two as needed in a true bypass situation. What's not to love here?
sumgai
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Post by JohnH on Aug 11, 2006 19:24:47 GMT -5
In Unks scheme, the hanging coil is hanging from ground only, where it cannot pick up any noise. Shunting coils is a theoretical problem, in which a low resistance circuit is made within one coil by shorting its ends. This allows larger currents to circulate within it. These dont get into the signal, but they suck power from the strings, damping them. Its like regenerative braking on an electric train. i have never heard it, but others round hesr are sure they have, and the theory is good. So we may as well avoid it if we can.
Ill have a go at that diagram - no problem!
John
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Post by UnklMickey on Aug 11, 2006 19:38:10 GMT -5
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Post by UnklMickey on Aug 11, 2006 19:44:11 GMT -5
If you can do that for me I will be most grateful. Tube of Smarties in the post. I presume its 'just' a case of connecting the red + whites to the correct push-pull poles in a different order? no, it's more than that! you only use red + white for ONE of the pickups. the other one uses black + green for the "series link" i was busy drawing while this conversation continued, so i'm just catching up on things. it might actually be worth waiting for John to dice up the SD drawing. that way you'll have the whole thing, in one shot. unk
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Post by JohnH on Aug 11, 2006 20:12:08 GMT -5
Unk - (or anyone) Do you happen to know, in SD convention, whether red/green or black/white is consistently the adjustable coil? It would be nice to be able to predict which coils you get, so that the bridge coil single coil towards the neck can be chosen.
John
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Post by UnklMickey on Aug 11, 2006 20:19:18 GMT -5
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Post by JohnH on Aug 12, 2006 0:47:06 GMT -5
Heres a fixed version of the SD diagram, based on Unkl's schematic, with a push/pull to coil-cut both Hb's: Its not beautiful, but it should work. In coil cut mode, it should deliver the screw coil at the bridge and the slug coil on the neck. You can choose how to arrange the pups, but I think I would spin the bridge one around so the screw coil faces the neck. Also, the grounding would be better if it was all taken to the volume pot case, instead of some to the the tone pot. cheers John
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Post by flateric on Aug 12, 2006 3:19:24 GMT -5
That's great. Many thanks guys!
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Post by sumgai on Aug 13, 2006 3:40:11 GMT -5
John, You've made an assumption, that being that top-most wire we see is connected to the "hot" side of the circuitry. In point of fact, without labels, the diagram shown could be hooked up either way, and it would work. And if I'm not greatly mistaken, the jury is still out on whether or not 'coils hanging from hot' are in fact noise antennas that can hurt a signal.
What you just described might make a "poor man's" sustainer, no? Except that it would be unpowered, but think about it..... a string vibrates, the physical movement is adduced by the pickup, which changes it into a magnetic flux deviation, which in turn is changed into an electrical current. By the reasoning you point out above, that process is reversed, albeit in a very small degree, but nonetheless, it should indeed be able to induce a longer sustain within the string, given all else being equal.
Only problem being, if the electrical current is completely shorted out (the shunt), then there can't be any conversion into magnetic flux lines being cut, nor can there be any additional "pull" exerted on the strings, beyond the pull found when the strings are at rest. Eddy currents within the windings and core of the coil might do it, but I should think that if they're large enough to cause this kind of action, then what are they doing to the overall output in the first place?
In theory? I don't buy it. But I want/need more data before I take a permanent stand, one way or the other. Anybody got any links or references they can share on this topic?
sumgai
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Post by UnklMickey on Aug 14, 2006 10:27:05 GMT -5
...What you just described might make a "poor man's" sustainer, no? ... sadly, no. quite the opposite. with a high impedance connection between the ends of the coils, there will be almost no energy required to produce the voltage seen there. however, when the end are shorted, the current produces heat (current flowing through resistance). this energy does come from somewhere...the movement of the strings. i doubt you will find much hard data on the subject, but i can give you one data point. many years ago, i decided to wire a 2 HB guitar in series. i was dissatisfied with the way it sounded, and further experimented by keeping the series wiring (global) and wired the pickups in local parallel. it sounded, okay with both pickups on. but when i turned off the bridge pickup by shunting it, i thought i could detect a loss of sustain. with the bridge pickup on, and the neck pickup shunted. there was no doubt.as i look back on this, i believe having the pickups in local parallel would cause more dynamic braking than a standard (local series) connection. none-the-less, i am certain shunting will cause some loss of sustain, and avoid the practice whenever possible. as far as hanging from Hot goes, the unused coils or pickups WILL act as antennae. will it be enough to be noticeable? i believe probably. the point is, if i can accomplish my goals without these practices, i definitely will do so. that's my story, and i'm sticking to it. unk
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Post by UnklMickey on Aug 14, 2006 10:37:46 GMT -5
Heres a fixed version of the SD diagram, based on Unkl's schematic, with a push/pull to coil-cut both Hb's: Its not beautiful, but it should work. In coil cut mode, it should deliver the screw coil at the bridge and the slug coil on the neck. You can choose how to arrange the pups, but I think I would spin the bridge one around so the screw coil faces the neck. Also, the grounding would be better if it was all taken to the volume pot case, instead of some to the the tone pot. cheers John John, eventually SD is gonna have someone point them to this site. when they (and GuitarElectronics) see how you have been altering their drawings, they'll either send you a nasty e-mail about altering their copyrighted image, OR (if they have any sense) they'll offer to put you on the payroll, to proofread all their drawings. unk
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Post by JohnH on Aug 14, 2006 16:03:21 GMT -5
Unk - yes, either way I can live with it!
John
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Post by sumgai on Aug 14, 2006 16:18:46 GMT -5
unk, Dynamic braking is another term for a reverse-phase sustainer! But otherwise, we've already come to the same conclusion, with the exception of your data point. I have to express a bit of wonder, would a non-guitarist have been able to tell the difference? Under blind-fold test conditions? Might be interesting, but as you say, it's pretty academic anyways - why go there if you can avoid it by proper design in the first place. sumgai
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Post by UnklMickey on Aug 15, 2006 12:04:47 GMT -5
...I have to express a bit of wonder, would a non-guitarist have been able to tell the difference?... DK,DC. that would never be a benchmark for me. unk
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Post by ux4484 on Aug 15, 2006 13:13:25 GMT -5
Well, I had wired my Tele copy via the McCarty schematic on Guitarelectronics with a set of GFS "modern vintage" mini HB's. When in HB mode, it's pretty sweet, but is a tad noisy in SC mode in the bridge position (though much less than the original setup). Wanting to keep as much of the single coil Tele sound/feel as I could, I opted for 250k pots as opposed to the usual 500K for humbuckers. It's not much work to convert it to JohnH/unklmickey's setup, I think I'll give it a spin.
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Post by UnklMickey on Aug 15, 2006 15:02:01 GMT -5
i think if i were using SC sized HBs, i wouldn't split them.
i would instead, have a (local) series/parallel switch for each one.
each pickup when used alone will still be hum-canceling. it doesn't require another single to cancel with.
this is NOT true for HBs that are split.
unk
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Post by ux4484 on Aug 15, 2006 16:08:42 GMT -5
Funny, I had already decided that the split sound was worth having; indeed it sounds better in the neck position than the original cortez pup.
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Post by UnklMickey on Aug 15, 2006 16:18:03 GMT -5
i know you will hear a BIG difference between local series and split on a SC sized HB.
i think you will find local parallel and split to be very similar. (much less different than a full sized HB would be, going between these modes)
and local parallel will be hum-canceling.
if you have the opportunity to experiment, and can wire for this comparision, i think you will find them to be quite similar.
i don't have a guitar with SC sized HBs, but from others i've talked to, this seems to be the consensus.
unk
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Post by ChrisK on Aug 15, 2006 16:43:17 GMT -5
Ackshully, I posted on this effect. In the ToggleCaster, where both the neck and bridge pickups are shunted when off, this effect is most noticeable. Since a series chain required at least two pickups to be selected for series (if only one was selected, it was open circuit), having one pickup on (neck or bridge) and the other (bridge or neck) switched between off and series, I could hear the harmonic difference while a plucked note decays.
This makes great sense since the loading of a generator tends to remove harmonics (lower energy) first. And a generator shorted thru its internal impedance does more work (steals more pluck'ular energy) than one that isn't.
I wasn't looking for this effect, it was really just a "what the heck" tonal observation. And then I remembered what the switching scheme did (the shorting was just an optimization for existing SP3T switches).
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Post by ux4484 on Sept 9, 2006 16:21:02 GMT -5
I did finally tinker around with this a bit. Sorry unk, after hand wiring it both ways, I didn't feel the series/parallel option was worth it with my SC sized HB's. The split coil mode in the neck pup is too desirable for me give up (It's exactly the sound of Mike Wanchic's Tele in "When Martha comes to town" by John Mellencamp). I did end up switching from the Guitarelectronics wiring I had to (pretty much) your's and John's above....though I had to wire the bridge pup to have SC mode be the north coil (pointing towards the neck), because the poles are bars in the GFS's, and the south pole is not actually under the high E string in the bridge, so it was a tad weak. The bridge pup also quieted down hum-wise when I was all done.
I thank you and John (and all the gods here) for putting forth such excellent effort just to see hacks like me be happy with their axes...FOR FREE!
Here's something you probably don't hear too much around here: I'm DONE working on my Tele, and am perfectly happy with the sound, wiring, and switching on my guitar...and I do not intend to change it (any time soon).
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Post by JohnH on Sept 9, 2006 17:08:34 GMT -5
Here's something you probably don't hear too much around here: I'm DONE working on my Tele, and am perfectly happy with the sound, wiring, and switching on my guitar...and I do not intend to change it (any time soon). Congratulations on getting it going. But we'll only believe that you are really 'done' when you start talking about the next axe that you plan to rewire. Until then, your Tele is not safe from thoughts of - 'what if I just added an extra.......' cheers John
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Post by ux4484 on Sept 11, 2006 9:23:39 GMT -5
heh... I had a whole post prepared, but I decided it would make a better thread than a response. As far as what's left....my Bass (a fender JP-90) is perfect the way it is (noOOOoooo toucheeee) as are my two acoustics. So guitar-wise I'm done...for now. Though I am anxiously awaiting the refurbish on my Jensen 12" gold label special design instrument speakers from my 1954 Allied electronics speaker cabinet !!! And I do have that "other" nagging project....I have to re-line the Tele's case..... note to self: Never try to clean the inside of a 30 year old guitar case with an air gun....even with a low pressure nozzle
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Post by ChrisK on Sept 11, 2006 18:21:59 GMT -5
IMHO, a coil hanging from the output rail (pre volume) will have a high frequency coupled effect. Essentially, any EMF sensed by this coil will be connected to the output rail on one end, and be capacitively coupled to the common via the shield/lead and/or the coil/magnet/screw/slug/frame capacitance (if either so exists) on the other end. I'm fairly certain that this is a merrily small value of 's of pF, so the coupled noise (and string signal) will be semi-minute (how's that for a meaningless specification)?
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