xeroks
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Post by xeroks on Jun 17, 2009 6:43:06 GMT -5
I'm sure this is no new idea, but here's the theory... I was thinking about one of the annoying things about swapping between a single coil guitar and one with humbuckers: volume. If I set my amp up so it sounds good for one, the other either sounds too weak or too distorted. Yes, I have heard the myth that volume knobs are able to stop between 0 and 10. It's up there with the Apollo landings, Roswell and Megan Fox . Anyway, as I was pondering these things (the last mostly), it occurred to me that if you have a standard 4-core humbucker, you could easily rewire your split coil switch (you do have one, right?) so that when both coils are on, a resistor is put in series, thus making it a bit quieter. STOP, STOP I hear you say - you're making my lovely loud guitar all quiet. I say this to you: turn up your amp. In these days of modeling amps and so on, that little bit of extra volume isn't going to really make much difference to the tone. What it does mean is that (once your amp has been turned up) your single coil sounds will be more in balance with the humbucker sounds. Also - to return to my original musings - you should be able to swap to your single coil guitar without so much mucking around. And Ms. Fox will agree to be in your next "home movie". You don't even need an extra pole, so if you use the one switch for 2 pickups, it will still work. If you have a series/parallel/single coil switch, it's even easier - you just replace the wire which does the "series" connection with a resistor. Downsides - I'm guessing that by making your amp louder, you must be adding extra noise. Also the exact value of the resistor must depend on the pickup, and possibly personal taste. Will that resistor react to capacitors in tone controls etc.? That's outside my expertise, maybe someone else can chip in. Diagrams to follow, in case it's not obvious what I'm talking about.
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xeroks
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Post by xeroks on Jun 17, 2009 6:58:44 GMT -5
I'd also like to point out the "usless" is a deliberate misspelling, indicating that denizens of guitarnutz2 are unlikely to approve of such things.
ahem.
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Post by newey on Jun 17, 2009 9:43:06 GMT -5
xeroxs-
We've had discussion before about using a resistor to better match the output of a SC and a HB in the same guitar. But, let me get this straight, you want to add a resistor to one guitar so that the output matches another guitar?
Since (broken strings aside) one is not usually switching to another guitar mid-song, why do you perceive this to be a problem? Just adjust it at the amp when/if you switch. Or use a volume pedal. Or, god forbid, the volume control on the guitar.
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xeroks
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Post by xeroks on Jun 17, 2009 9:55:09 GMT -5
matching it up to the other guitar is just a "well that's handy". On my amp (a vox vst) i can program the settings in 2 channels which i can switch via footpedal. that's fine if you're using 1 guitar.
however if you've got a second guitar that's got a different volume, you need to change the gain settings on each program. it's not really doable whilst performing.
I used to use a programmable pedalboard, which was less of a problem - i just had a separate set of sounds for each guitar.
However, the main thrust of the suggestion is to get the series and single coil sounds on the one guitar more in balance.
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Post by ashcatlt on Jun 17, 2009 11:07:39 GMT -5
Wait, what? The discussion re: coil-split switches led me to believe we wanted to match the volume between pickups in the same guitar. Aw well, my answer's the same anyway. Series resistance doesn't actually do a whole lot in the way of volume attenuation. 5spice is showing about a 3db drop across most of the lower frequencies with a 500K resistor. One would expect that a pair of mostly evenly matched coils in series would have approximately double the output volume of either one alone. That's 6db. Anyway, the big thing that this resistor does is to alter the cutoff frequency of our LCR filter, severely attenuating high frequencies. These are generally lacking a bit already in an HB when compared to an SC. I don't think you'll be able to get these matched in volume and still be able to stand the tone of the HB. A big part of the reason I switch from SC to HB (whether in one guitar or between two) is get more volume and/or more crunch out of the amp. Maybe I'm just silly.
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xeroks
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Post by xeroks on Jun 17, 2009 11:43:38 GMT -5
i knew it would be too easy!
I thought the change in tone between sC and humbucker was down to the coils acting as an inductor, and that an extra resistor would be relatively neutral from a tone point of view.
I suppose an alternative would be to switch an extra volume control in after both coils, though you'd have to have an extra pole to do it, i think, making the whole thing a lot less simple.
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Post by ChrisK on Jun 17, 2009 15:35:42 GMT -5
No, it's just futile. Yes, there is a higher output generator driving the load through increased internal inductance. Well, the internal inductance, internal inter-winding capacitance, series coil wire resistance, parallel resistance (volume pot), parallel impedance (the tone pot and cap), the cable capacitance, and the amp input impedance all comprise a common passive network that completely interacts. The pickup alone looks like a series LCR network where the R, like every other component of this network, does not act alone. Here's a link on Pickup Coil Response Tuning, and here's one on The Passive High-Cut Tone Control]. It would be fairly easy to run a simulation showing the relative attenuation and relative changes in frequency response from an increasing Rseries in a pickup structure. It's not elementary, my dear Watson, just plane complex.
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Post by ashcatlt on Jun 17, 2009 16:03:03 GMT -5
It would be fairly easy to run a simulation showing the relative attenuation and relative changes in frequency response from an increasing Rseries in a pickup structure. Like this? The circuit uses numbers from JohnH's Guitar Frequency Response Calculator - PAF HB and 10' cable: R2 is our series resistor. Sweeping it from 0 to 500K ohms gives us this: Okay, it's more like -4db. For comparison, here's what happens when we sweep the Volume control:
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xeroks
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Post by xeroks on Jun 17, 2009 17:36:16 GMT -5
how about something like this? so it's pretending to be volume control? (modified size of graphic)
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Post by ChrisK on Jun 17, 2009 18:09:29 GMT -5
I might suggest that the swept (variable) resistance should be in series with, and next to the 7 K internal pickup resistance, before the 130 pF inter-winding capacitance, but certainly before the volume pot. I don't know, what is this pretending to be? ;D (Some lines are missing (too much image compression) and I don't recognize the blue'blob'ular things.)
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Post by JohnH on Jun 17, 2009 18:30:55 GMT -5
The easy way to cut down the Hb output, and not risk some dullness is to wire the coils in parallel, which also makes it sound a bit brighter. It brings the overall magnitude of signal output down to that of a single coil, on the basis that two coils in parallel have similar output voltage to one coil.
To do the thing with resistors however, it might be possible to find a specific treble bleed circuit to put with it, tuned to give the nearest tonal balance at the specific volume reduction being sought.
John
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Post by ChrisK on Jun 17, 2009 18:36:02 GMT -5
That's a good suggestion John. And while one is at it, they could perform some Pickup Coil Response Tuning and make it sound series'ously similar to a series humbucker'ski. It's much easier to take harmonic content out if it's in there in the first place (it's real hard to put in in if'n it ain't).
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Post by JohnH on Jun 18, 2009 1:54:13 GMT -5
Since going to parallel coil wiring will quarter the pup inductance and resistance, then to get somewhat the same tone as when series wired, 4x the cord capacitance is indicated. This will approximately match the resonant peak of the resulting LRC circuit.
So since 1x cord capacitance is provided by the cord, then an extra 3x could be applied as an extra cap, wired across the pickup. Not to over do it, it suggests that something in the range 1nF to 2nF might be a good starting pint for experimentation On the other hand, the bright tone of parallel coils might be considered better anyway.
John
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xeroks
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Post by xeroks on Jun 18, 2009 3:46:57 GMT -5
I've made that graphic bigger - have the lines appeared?
though, the way the discussion has gone, it's clearly redundant!
the "blobular things" are a special new design of pickup coil which are the wrong shape to fit in any guitar. but pretty, don'tcha think?
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xeroks
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Post by xeroks on Jun 18, 2009 7:49:20 GMT -5
nice link, by the way Mr Display Name, and welcome to GuitarNutz2!
It may take me a while to get my head round some of that lot. Herr Lemme's page is excellent. I think. It gives me a lot of ideas in the "run before you can walk" category.
By the way, your style of writing is very reminiscent of a long-time denizen of this site - is he any relation, by any chance?
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Post by ashcatlt on Jun 18, 2009 12:49:13 GMT -5
I might suggest that the swept (variable) resistance should be in series with, and next to the 7 K internal pickup resistance, before the 130 pF inter-winding capacitance, but certainly before the volume pot. Oh, like this then: The V pot has been replaced by a fixed resistor. I'm not sure exactly how we'll get this resistor before the internal capacitance of the pickup, but it sure seems to make a difference: There's quite a bit more attenuation. Now the question: Why? If it's AC, why does it matter where we put that resistor?
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Post by ChrisK on Jun 18, 2009 17:03:35 GMT -5
**** IN PROCESS **** In your former example, the resistance is effectively between the pickup/volume/tone structure and the amp input impedance. You're displaying the response at the amp input. You're strongly driving (7 K resistance) the 130 pF cap and variably driving the 500 pF input cap||1 M input resistor. In your latter example the resistance is effectively between the two pickup coils (as suggested) and forms an integral part of the output impedance of the basic pickup itself, which is driving the cable capacitance and the amp input impedance. You're displaying the response at the cable output/amp input. You're variably driving the 630 pF combined input cap||1 M input resistor. Are you for sure not varying the tone control pot? Everything matters positionally except for non-coupled (ie no mutual inductance) passive elements in a two-terminal (connection) series network or string OR a non-coupled (ie no mutual inductance) two-node parallel network (where all components share just two common nodes). For instance, the series structure of the pickup inductance and its internal resistance is not affected by the resistance or inductance order. The series structure of the tone pot and its tone cap is not affected by the order of these components (either the pot or (but not and) the cap can be connected to ground) The parallel structure of the volume pot (as a fixed resistance) and the tone circuit as a two-terminal network in parallel with the volume pot is not order dependent.
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