axedoctor
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Post by axedoctor on Jan 18, 2017 19:17:55 GMT -5
Hi Nutz - Some inspiring ideas in other threads wrt modding a Les Paul for Jimmy Page features. The issue for me was that an appropriate axe on which to perform the required surgery demanded more of a budget than I was willing to commit, so I began thinking about what might be done with a lower price point Epiphone Les Paul Special II. Given the limitation of two pots and a single-hole pickup selector switch, I have crafted the following wiring. The key design aspect is replacing the 3-way toggle switch with a 4P5T rotary switch to achieve the lone/parallel/series combining, leaving the two push/pull pots to support the coil split and phase swap features. We'll start with a single-setting master tone control and see if its performance is acceptable. If not, then a drillin' we will go. As always, your feedback is coveted - especially if I have made some glaring error. here is the schematic : Volume Control VR1 : 500kΩ audio taper Neck Pickup Coil Split PP1 : DPDT push/pull switch Treble Control VR2 : 500kΩ audio taper (R2=###kΩ, C2=33nF) Bridge Pickup Coil Split PP2 : DPDT push/pull switch Pickup Selector SW1 : 4P5T rotary switch Treble Compensation (R1=150kΩ, C1=1nF) here is the feature set : ---- #1 : Neck in Series with Bridge ---- #2 : Neck Only Pickup Selector ---- #3 : Neck in Parallel with Bridge ---- #4 : Bridge Only ---- #5 : Neck in Series with Phase-Swapped Bridge Neck Coil Split Up : Neck North Active Dn : Neck Humbucker Active Bridge Coil Split (#1-#4) Up : Bridge South Active Dn : Bridge Humbucker Active Bridge Coil Split (#5) Up : Phase-Swapped Bridge North Active Dn : Phase-Swapped Bridge Humbucker Active "Nurse ... scalpel please."
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Post by newey on Jan 18, 2017 22:09:37 GMT -5
Your gas-passer can begin to anesthetize the patient. The schematic checks out OK by me.
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axedoctor
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Post by axedoctor on Jan 27, 2017 0:08:18 GMT -5
Following some further investigation, I began to consider implementing series/parallel switching for the humbuckers rather than coil split and arrived at a far more elegant design than my previous post. Better yet, with only a very minor variation, it can implement the original coil split combinations so I should be able to easily A/B the two designs. Volume Control VR1 : 500kΩ audio taper Neck Pickup Coil Mode PP1 : DPDT push/pull switch Treble Control VR2 : 500kΩ audio taper (R2=###kΩ, C2=33nF) Bridge Pickup Coil Mode PP2 : DPDT push/pull switch Pickup Selector SW1 : 4P5T rotary switch Treble Compensation (R1=150kΩ, C1=1nF) ---- Position 1 : Neck in Series with Bridge ---- Position 2 : Neck Only Pickup Selector ---- Position 3 : Neck in Parallel with Bridge ---- Position 4 : Bridge Only ---- Position 5 : Neck in Series with Phase-Swapped Bridge Neck Mode Up : Neck Coils in Parallel Dn : Neck Coils in Series Bridge Mode (#1-#4) Up : Bridge Coils in Parallel Dn : Bridge Coils in Series Bridge Mode (#5) Up : Phase-Swapped Bridge Coils in Parallel Dn : Phase-Swapped Bridge Coils in Series
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Post by newey on Jan 27, 2017 6:58:24 GMT -5
That, too, checks out OK. It is SOOO nice when folks draw schematics rather than diagrams.
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axedoctor
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Post by axedoctor on Jan 27, 2017 10:56:45 GMT -5
many thanks, newey ... I'm an EE by trade, so starting with a schematic is just how I roll ... developing & implementing the accompanying wiring diagram follows and introduces another set of constraints ... I am actually somewhat concerned that all of this stuff will fit in the standard electronics cavities of the target axes ... then again, if a router must be employed, perhaps it opens up some extra possibilities ... I have already drawn up another version that adds another potentiometer and provides individual tone control for each pickup
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Post by newey on Jan 28, 2017 7:47:42 GMT -5
If you're an EE, then I guess you don't really need me to vet your work. I am forever cautioning newcomers with grandiose schemes to make sure it all fits the cavity first, and to leave room for wires to radius corners. It's not enough that the components fit if there's no space for the wiring to be properly routed. People seem to think wire is infinitely flexible . . . Our late member 4Real always advised using a cardboard template of the cavity, with holes for the pots, switches, etc. The template is used to double-check fitment, and then as a base for soldering. Once completed, one has a wiring harness that should drop right into the cavity.
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axedoctor
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Post by axedoctor on Jan 28, 2017 9:57:47 GMT -5
"many hands make light work" and "many eyes make right work" ...
so here's a question that I am pondering regarding "separate" tone controls for a two-pickup guitar ... without venturing into the world of active buffering, using the selector scheme from this design and moving the tone controls before the selector, whenever pickups are combined in parallel the impact of each pickup's tone control will be "shared" with its partner pickup - how does the player deal with this when switching between a selector setting that utilizes either single pickup to another that utilizes both???
do the tone controls act more independently when the tone control is placed before the selector and then the pickups are combined in series???
are there any threads on GN2 that deal with this issue?
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Post by JohnH on Jan 28, 2017 14:20:31 GMT -5
"many hands make light work" and "many eyes make right work" ... so here's a question that I am pondering regarding "separate" tone controls for a two-pickup guitar ... without venturing into the world of active buffering, using the selector scheme from this design and moving the tone controls before the selector, whenever pickups are combined in parallel the impact of each pickup's tone control will be "shared" with its partner pickup - how does the player deal with this when switching between a selector setting that utilizes either single pickup to another that utilizes both??? do the tone controls act more independently when the tone control is placed before the selector and then the pickups are combined in series??? are there any threads on GN2 that deal with this issue? All true, for reasons that are obviously obvious to you. I don't know specifically in practice, because some players are expert at pulling subtly tweaked tones out of LP's, and they tend not to be wiring nerds. I think the basic use of two tone controls is just so you can pre-set your B and N tones for when you use them separately. The that way they get blurred together in the combo setting is just a time-honoured disadvantage/design feature of this ancient basic scheme. With tone pot before the volume (= modern wiring, as on all production guitars), you can at least, turn one or both volume pots down a little, which adds a bit of electrical separation between the two pickups with their tone pots. Then if you turn one tone all the way down, the other pickups is less affected by it. In series mode, there is more opportunity to keep things separate, if you put the whole pickup/tone control/volume pot grouping, all as a unit, in series with that of the other pickup. I haven't checked into your scheme, is that what you do? My own series-wired guitars do this and it works well so you can turn neck fully down and still get full treble from the bridge. In fact you get even more treble from the bridge because the low impedance path through the tone cap of N, when N tone pot is turned down, lets the B treble get through more easily.
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axedoctor
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Post by axedoctor on Jan 28, 2017 15:13:29 GMT -5
appreciate you chiming in John The ideas herein presuppose starting with a 1T 1V HH instrument and thinking that perhaps some enlargement of the electronics cavity could enter into the equation in order to find room for the P/P pots and the rotary switch. If that does occur, then adding one additional pot should be a possibility and I was thinking that a 2nd tone control might be the logical choice (for the reason you mention). Had not considered a 2nd volume control instead or in addition. To do so using my selector scheme, I thought that positioning them as shown below would be appropriate ... yes/no? btw, I ran numerous simulations with GF to help with choosing specific passive components for the Strat design I shared on another thread ... very helpful (kudos)
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Post by newey on Jan 29, 2017 8:31:19 GMT -5
As you note, Doctor, you'll have interaction of the tone controls with dual tones and one master volume. AS JohnH notes, even with two volumes, there is still not complete independence. The way you show it is the way it's typically done, and is best to my thinking.
However, a better solution is to use a dual-gang pot for the volume, then wire it in typical LP fashion. if you can fit an extra pot, a dual-gang should be workable as well. You'd still have the interaction one gets on a regular 4-pot LP, but it's still better as John noted.
A Strat has the same interaction at position 4 (N + M), where both tone pots are active. I suspect most Strat players don't even know this since they don't use the tone controls.
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axedoctor
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Post by axedoctor on Jan 30, 2017 1:16:51 GMT -5
Newey & John - would this be a viable approach to incorporating a dual stacked concentric potentiometer so as to achieve independent volume functionality? Dual Volume Control VR1{A,B} : 500kΩ audio taper (R1{A,B}=150kΩ, C1{A,B}=1nF) Pickup Selector SW1 : 4P5T rotary switch Bridge Treble Control VR2 : 500kΩ audio taper (R2=###kΩ, C2=33nF) Bridge Pickup Coil Mode PP2 : DPDT push/pull switch Neck Treble Control VR3 : 500kΩ audio taper (R3=###kΩ, C3=33nF) Neck Pickup Coil Mode PP3 : DPDT push/pull switch ---- Position 1 : Neck in Series with Bridge ---- Position 2 : Neck Only Pickup Selector ---- Position 3 : Neck in Parallel with Bridge ---- Position 4 : Bridge Only ---- Position 5 : Neck in Series with Phase-Swapped Bridge Neck Mode Up : Neck Coils in Parallel Dn : Neck Coils in Series Bridge Mode (#1-#4) Up : Bridge Coils in Parallel Dn : Bridge Coils in Series Bridge Mode (#5) Up : Phase-Swapped Bridge Coils in Parallel Dn : Phase-Swapped Bridge Coils in Series
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axedoctor
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Post by axedoctor on Jan 30, 2017 18:09:25 GMT -5
uh-oh ... was browsing some guitar design videos and stumbled upon one where a modder was lamenting that while "reverse wiring" volume pots to eliminate their interaction introduces a significant problem when also attempting to utilize treble bleed to make the frequency response more uniform as volume is decreased the individual was using the single capacitor version of the TB circuit, but the parallel RC circuit that I have employed will exhibit the same issue saw some mention that ChrisK might have liked the series RC network version with 130k & 1.2nF ... this seems to have some promise for reducing the unwanted side effect will need to look at this some to see if I am not faced with a Catch-22 ... not yet sure about the net effect as the two circuits interact to pass treble from one pickup to the output while also doubling as a limited treble cut across the other pickup depending on the relative volume settings the updated schematic would be : any ideas???
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axedoctor
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Post by axedoctor on Jan 31, 2017 11:39:13 GMT -5
thought about this some more and realized that positioning the volume controls prior to the 5-way rotary switch might provide the opportunity to limit the undesirable interaction to raise its ugly head only when the pickups are combined in parallel (position #3 in this design) after redrawing the schematic a bit, I further realized that there is now a choice to either discard the treble bleed for one of the pickups when in position #3 or accept the side effect when the pickups are connected in parallel (blended may be a better term, given the dual volume control architecture) also discovered that phase-swapping the top of the series pair (Neck) was necessary to get everything to piece together properly a bunch of changes here, so given my propensity to make errors and incorrect assumptions, I covet your feedback Dual Volume Control VR1{A,B} : 500kΩ audio taper (R1{A,B}=130kΩ, C1{A,B}=1.2nF) Pickup Selector SW1 : 4P5T rotary switch Bridge Treble Control VR2 : 500kΩ audio taper (R2=###kΩ, C2=33nF) Bridge Pickup Coil Mode PP2 : DPDT push/pull switch Neck Treble Control VR3 : 500kΩ audio taper (R3=###kΩ, C3=33nF) Neck Pickup Coil Mode PP3 : DPDT push/pull switch ---- Position 1 : Phase-Swapped Neck in Series with Bridge ---- Position 2 : Neck Only Pickup Selector ---- Position 3 : Neck in Parallel with Bridge ---- Position 4 : Bridge Only ---- Position 5 : Neck in Series with Bridge Neck Mode (#1) Up : Phase-Swapped Neck Coils in Parallel Dn : Phase-Swapped Neck Coils in Series Neck Mode (#2-#5) Up : Neck Coils in Parallel Dn : Neck Coils in Series Bridge Mode Up : Bridge Coils in Parallel Dn : Bridge Coils in Series
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Post by newey on Feb 1, 2017 7:10:13 GMT -5
AD-
Hold the fort for a bit. Work calls, it may be a day or two before I can look this over. I think you are right as far as interaction of the controls, it's always a trade-off.
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tonegeek
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Post by tonegeek on May 25, 2017 6:37:24 GMT -5
AD, if you're still looking for a solution to get the JP features on a LP Special II, you might want to check out ToneFiend's Pagey project part 2. www.seymourduncan.com/tonefiend/?page_id=7346&preview=trueIn Part 1, he used the traditional JP wiring. However, in Part 2, he switched to using Seymour Duncan Triple Shots to control each humbucker's wiring independently. This enabled him to only need 2 push/pull pots to control series/parallel and phase between the pickups. I too have been considering wiring up a LP Special II (actually the Slash AFD version) with JP-like features and if I were to, I think this second route is the way I'd go. Also, do you know if the LP Special II has humbuckers with 4 wires or 2 wires? I suspect it is 2 wires and you would have to separate the individual wires. www.1728.org/guitar1a.htm
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