ALTERNATIVE WIRING FOR PARTIAL COIL CUT. THEORY InPUT APPRECIATED

[Gstring]

.
Have been experimenting for some time with the re wiring one of my favourite 2 vol 2 tone mahogany/maple arch tops. It has 4 CTS push pulls which now give Artie's coil swap , partial coil cut for each pup and a combined Series/OOPs. Have now found a wiring I like but would be interested to learn what is happening theory wise.re the partial coil cut.

My trial and error experiments have been primarily with the partial coil cuts to get a slightly better (different?)sound than either standard parallel or a straight coil cut. Experiments comparing sounds after adjustments with a single guitar are always a bit hit or miss relying on ear memory but I think I am getting to where I want to be.

I have found that I prefer the sound of partial coil cuts so that the by bypass filter works only on one coil when the pup is wired in parallel. See extract of my schematic. For simplicity PPs are shown as standard as opposed to convoluted CTS wiring. This wiring I think also gives improved sounds when both the coil swap and partial cut are engaged. Also I think I can hear a slightly sweeter sound iwith a small 0.05 cap added in series to the resistor.

I am at the moment using 500k pots( cheap imports I had lying around) as resistors to find a value I like . Current favourite values seem to be around 375 ohm for the bridge and 210 for the neck. Single resistors of similar values will eventually be fitted to neaten things up under the hood.

My electrical theory is very limited and I would be interested to learn from some one more knowledgeable what is the difference in terms of current flow of wiring a partial coil cut as normal (as in fig 1) or of how I have wired it (fig 2) . Also what is it that happens to the “frequency filter” when you wire a small cap in series with a resistor as I have done. I was intrigued out of curiosity to try resistor and cap in parallel as per the de mud mod but never got around to it. If anybody can tell me the likely result in a partial ciol cut situation it would be appreciated.

 

[Jack_TriPpEr]

Hi Gstring,

The concept of a applying a cap and resistor to the series link between 2 coils of a humbucker is also employed by this modified pot made by PMT, available for sale on the guitarelectronics.com website. I have one of these pots on-hand and hoping to install it soon, just have not had the chance. In the case of this PMT product, the pup remains wired in series. Ref: https://guitarelectronics.com/hcp-pa...-coil-filters/

A couple months ago I started a thread in this forum asking if anyone had experience with this product but it didn't get any responses, from what I recall.

Am I understanding your "coil-swap" push-pull correctly, that it looks like you are pairing up one coil from the bridge pickup with one coil from the neck pickup?

 

[Jack_TriPpEr]

You mentioned series/OoP earlier. If that means putting one pup's coil in series with a coil from the othet pup, please note that that PMT HCP product that i mentioned has a common ground, so you would lose the capability to do the In Series option if you used that product.

 

[Jack_TriPpEr]

Gstring,

The ideal values for the resistors will vary depending on what pickups are being used, driven by the DC resistance spec of the pickups.

What make and model of pickups are you using?

 

[Gstring]

Hi Jack
Thanks for your responses

The pups I am using are Irongear Blues Engine in the neck and a Dirty torque in the bridge. They are excellent pups based on the Tonerider A4 and a JB. . I have actually taken them off another guitar.I had As I stated I think I have already found some pretty good resistor values.for the partial coil cut

The coil swap was devised by Artie of this forum and puts the slug coil of one pup with the screw coil of the other and gives additional "virtual" humbuckers. Usually in series but as you can see from my diagram, by using a push pull. you can put them also in parallel.althugh in my wiring the screw coil is partially cut due to the bypass.The wiring for the neck pup is of course not shown.


The series oop wiring is not shown. This puts the neck and bridge pups in series and out of phase. A sound I quite like.and a mod I have installed in many guitars.You are correct that special care needs to be taken regarding the circuit ground.

As regards the product you mention this seems to be going down the traditional (fig1) idea with an added cap and using a double concentric pot as a variable resistor for the two pups. As I am using 500k pots inside the guitar as my resistors I can obviously also vary the amount of coil cut and this is one of the things I have been experimenting with to find a good usable value.However my idea as you can see is to cut in parallel mode

I am pretty much all set and good to go with the wiring. Guitar is working and sounding good. Just need to tidy a few things inside. What I was hoping this post would bring was some technical imput on the points raised.

 

[Jack_TriPpEr]

Gstring,

if you ever post a demo to the web/YouTube/etc of what your scheme (of cap & resistor applied to the seriws link btw two coils of the same pickup connected In Parallel mode) sounds like , i would love to hear it.

Glad to hear that you like the sound resulting from your innovative scheme.

I am familiar w Artie's virtual humbucker, which consists of two coils from two different pickups. Artie likes to call it a "slut bucker". Lol

 

[Gstring]

I did once about 10 years ago, try and do a You Tube vid (with another) to demonstrate on both Humbucker and single coil guitars the sound obtainable using a single push pull to get combined Series /OOP .This was a wiring idea I worked out around 16/17 years ago. Although very pleased with my discovery which I have installed on very many guitars, others probably may have worked it out before me so I do not claim to be the originator. Spent quite a bit of time on the vid project but in the end was not happy with the result.. Sadly it would seem my talents as a producer and on screen are somewhat limited and my contribution to the community was not to post..

 

[Jack_TriPpEr]

Gstring,

Given your interest in getting singlecoil type sounds out of humbucker pickups, i wanted to recommend the Half Out Of Phase (HOoP) wiring option to you in case you had not heard of it. HOoP emulates the quack of Position 2 and 4 on a Strat; natural quack being a result of the close proximity of each pup to the other on a Strat - or any guitar w a middle pup. It doesn't replace splitting; It's meant as an additional option, to employ in combination with splitting.

Let me know if you'd like me to explain further about this wiring option.

 

[Gstring]

Hi Jack
Thanks again for posting

Have never had good results with my experiments with HOOP on humbuckers. I tried different cap values..Results a bit too subtle. However I have used this wiring idea extensively on Telecasters.as well as some other single coil guitars

I usually fit a standard 5 way and wire it to give both pups inparallel with a 0.05 cap and pups in series for the 2 extra positions. Then if you fit a push pull to give one of the pups an OOP function you can also get full OOP, HOOP and OOP in series. All good stuff.

Am a bit disappointed nobody has responded to this thread with some tech import as I originally asked.

Although I have quite a bit of experience with re wiring guitars and experimenting with ideas that come to me my theory knowledge is very basic and I always welcome the explanations.

 

[Jack_TriPpEr]

Hi Jack
Thanks again for posting

Have never had good results with my experiments with HOOP on humbuckers. I tried different cap values..Results a bit too subtle. However I have used this wiring idea extensively on Telecasters.as well as some other single coil guitars

I usually fit a standard 5 way and wire it to give both pups inparallel with a 0.05 cap and pups in series for the 2 extra positions. Then if you fit a push pull to give one of the pups an OOP function you can also get full OOP, HOOP and OOP in series. All good stuff.

Am a bit disappointed nobody has responded to this thread with some tech import as I originally asked.

Although I have quite a bit of experience with re wiring guitars and experimenting with ideas that come to me my theory knowledge is very basic and I always welcome the explanations.

PM Artie, Freefrog, or GuitarDoc and ask them to take a look at this thread. They might have simply missed it.

 

[freefrog]

PM Artie, Freefrog, or GuitarDoc and ask them to take a look at this thread. They might have simply missed it.

I had seen this topic but...

1) old mum has broken one of her legs so I've other kinds or "wiring" and "resoldering" to think about... :-/

2) I've simply not understood what Gstring wanted to know...



Gstring, here are my thoughts about your OP anyway:

In your pic, the schematic "1" shows a series humbucker with a resistor to ground between its coils. I don't see this signal path as a "partial coil cut" since both coils are involved: the resistor just acts like a "common" volume control permanently lowered for both coils. it should just squash the resonant peak of the humbucker of a couple of dB, as if the pickup was paired with lower resistance pots . Lowering a bit the tone control would do largely the same, IMHO / at first glance.

The schematic "2" shows the two coils of an humbucker in parallel. The resistor is now limiting the output level for ONE of the two coils only, by a large amount (I'd bet on more than 15dB if your resistor is a 210k one). In this case, yes, it's a "partial coil cut".

If you add a cap in series with this resistor, the 2d coil will be fitted with a high pass filter. So, you'll have the 1st coil full up while the 2d one will loose 15dB AND will produce less bass...
If you put the series cap in parallel with a 210k between ground and coil 2, the cap will keep acting like a high pass filter for coil 2 BUT the resistor won't influence the volume no more: it should just defeat partly the effect of the cap as a high pass filter...

The effect of such choices on the tone would depend on the pickup involved: the stray capacitance of each coil and the coupling between both coils can bring noticeable differences here, IMHO/IME/in my understanding.

That's all I can say. FWIW.


Back to "real" life with its own convoluted signal paths...

 

[Jack_TriPpEr]

I had seen this topic but...

1) old mum has broken one of her legs so I've other kinds or "wiring" and "resoldering" to think about... :-/

2) I've simply not understood what Gstring wanted to know...



Gstring, here are my thoughts about your OP anyway:

In your pic, the schematic "1" shows a series humbucker with a resistor to ground between its coils. I don't see this signal path as a "partial coil cut" since both coils are involved: the resistor just acts like a "common" volume control permanently lowered for both coils. it should just squash the resonant peak of the humbucker of a couple of dB, as if the pickup was paired with lower resistance pots . Lowering a bit the tone control would do largely the same, IMHO / at first glance.

The schematic "2" shows the two coils of an humbucker in parallel. The resistor is now limiting the output level for ONE of the two coils only, by a large amount (I'd bet on more than 15dB if your resistor is a 210k one). In this case, yes, it's a "partial coil cut".

If you add a cap in series with this resistor, the 2d coil will be fitted with a high pass filter. So, you'll have the 1st coil full up while the 2d one will loose 15dB AND will produce less bass...
If you put the series cap in parallel with a 210k between ground and coil 2, the cap will keep acting like a high pass filter for coil 2 BUT the resistor won't influence the volume no more: it should just defeat partly the effect of the cap as a high pass filter...

The effect of such choices on the tone would depend on the pickup involved: the stray capacitance of each coil and the coupling between both coils can bring noticeable differences here, IMHO/IME/in my understanding.

That's all I can say. FWIW.


Back to "real" life with its own convoluted signal paths...

Freefrog: sorry to hear about your mom. I hope she has a speedy recovery

 

[freefrog]

Freefrog: sorry to hear about your mom. I hope she has a speedy recovery

Thx, mate. I hope so.

 

[Gstring]

Hi freefrog Am very sorry to learn about your mother.. Sincerely hope all mends well in the end. Should do .These days medical skills and treatment are of a very high standard. My late mother sadly always had strength issues after she broke her arm when in her 60s .However that was 40 years ago.

Really appeciate your input. Don't expect a further response from you but will put down my thoughts anyway with a view .to getting some further input from elsewhere.

Although you say that Fig 1 is not a partial coilcut, this is how most wiring schematics show and describe it and is the wiring which appears on many PRS guitars. Also you say it is acting like a common volume control for both pups. I don't have the technical ability to disagree and I can see where the theory is coming from (volume pots are after all just resistors) and in fact the resistors I am using (for the moment) are pots. However in practice the sound you get is completely different from when you just turn down the pup's volume control. In my simplistic view the difference is caused by the fact the the pot being used as a resistor has no ground connection like a volume pot and theway it is connected to the two coils. I have no idea as to the proper theory.
.
From what you say you would think think that a cap alone taking out part of the bass frequencies would be the best way to do this but then it seems you are looking at the de mud mod.

Another wiring idea which I liked and came very close to using and may well go back to looking at again.was putting the cap on the other coil (see amended diagram) I actually liked this a lot but was frustrated by some soldering issues I had which may have clouded my judgment. Using your thoughts it seems that what I am doing in that instance is just lowering the volume of one coil and removing some low frequencies from the other.. Would appreciate if somebody can agree or disagree with that.

At the end of the day of course experimenting with wiring is all about finding something that in practice appeals to your own ears and the theory is immaterial . However it's sometimes good to know what is actually going on electrically.

 

[freefrog]

Hi freefrog Am very sorry to learn about your mother.. Sincerely hope all mends well in the end. Should do .These days medical skills and treatment are of a very high standard. My late mother sadly always had strength issues after she broke her arm when in her 60s .However that was 40 years ago.

Really appeciate your input. Don't expect a further response from you but will put down my thoughts anyway with a view .to getting some further input from elsewhere.

Although you say that Fig 1 is not a partial coilcut, this is how most wiring schematics show and describe it and is the wiring which appears on many PRS guitars. Also you say it is acting like a common volume control for both pups. I don't have the technical ability to disagree and I can see where the theory is coming from (volume pots are after all just resistors) and in fact the resistors I am using (for the moment) are pots. However in practice the sound you get is completely different from when you just turn down the pup's volume control. In my simplistic view the difference is caused by the fact the the pot being used as a resistor has no ground connection like a volume pot and theway it is connected to the two coils. I have no idea as to the proper theory.

Hi Gstring,

Thx for your kind words.

To answer on a hurry to your sentences above...

In you pic "1", the resistor between the coils seems to be going to ground. At least that's what I see / understand in your schematic.
IF this resistor is a high resistance one (like 375k or 210k and not 375 Ohm or 210 Ohm), it should react as I said (although I realize now that my previous answer sounds like a brain fart rather than a faithful expression of my thoughts. LOL).
IF the same resistor is a LOW resistance one it "almost" connects totally the first coil to ground AND effectively creates a "partial coil cut".
[My badly worded reasoning in post 11 was about a high value resistor, lke a 210k one... ].

Not enough time for further comments. I just hope my (botched) previous answer to sound less paradoxal now .

"More later" if time permits. Thx for you understanding and see ya!

 

[freefrog]

OK. While I was waiting a call from the hospital, I've tried to think about something else. So I’ve done a few sims that I share below. Each pic shows ten lines, translating the resonant peak of a humbucker whose coil splitting is progressively altered by a variable resistor (goiing from 500k to 0 Ohm).

Pic 1 illustrates what happens when a HB in series has the variable resistor between coils, going to ground (as shown by “Fig 1”, in post 1). As I’ve tried (and failed) to make it clear in my post 11, the resistor “mellows” the signal and “flattens” the resonant peak a bit like a tone control would do as long as its resistance is high. It’s only when this resistance is low that one coil starts to “loop” itself to ground, leaving the second coil working alone. That's where the resonant peak becomes higher pitched and the level much lower...


The second pic shows what happens when a HB wired in parallel has a variable resistor between ONE of its coils and ground (as shown by “Fig 2” in post 1). This time, the control affects essentially the frequency of the resonance, which is logical since it passes the HB from ¼ of its series inductance (in parallel) to half of this inductance (when split): it affects frequencies more than output level.

The third pic shows what happens with a cap in series with the variable resistor, as Gstring has wired it (if I’ve understood correctly what he said)…
...And that’s where my previous explanation was not complete at all. :-/
The 5nF cap has in fact TWO actions in this case:
-it acts like a tone capacitor to ground for coil 1;
-it's also a series capacitor between ground and coil 2 and works as a high pass filter for it.
These two functions contradict each other and create a “dip” in the mids, whose center frequency depends on the capacitance involved.
The red arrow in the pic shows where is this frequency with a 5nF cap: between 500hz and 1khz.
In fact, it’s a subtle variation on Gibson’s Fat Tap / tuned coils...

Don't know if this rambling is clearer than my previous posts. My overloaded mind made my answers wordy and unclear altogether. At least I'll have tried to share something...

Gstring, you're right anyway: theory is not supremely important compared to practical / musical experience.

 

[Gstring]

Hey Man

Seriously appreciate you finding time to respond . Am now a little less confused Thanks

 

[Jack_TriPpEr]

Gstring,

I wanted to thank you for posting about this concept of applying a cap & resistor to one of two coils combined in parallel. It is something I am very interested in giving a try. I am currently working up a custom diagram that will allow me to try that as well as try it to those two coils combined in series, so I can A-B compare both at the same time.

 

[Jack_TriPpEr]

.
Have been experimenting for some time with the re wiring one of my favourite 2 vol 2 tone mahogany/maple arch tops. It has 4 CTS push pulls which now give Artie's coil swap , partial coil cut for each pup and a combined Series/OOPs. Have now found a wiring I like but would be interested to learn what is happening theory wise.re the partial coil cut.

My trial and error experiments have been primarily with the partial coil cuts to get a slightly better (different?)sound than either standard parallel or a straight coil cut. Experiments comparing sounds after adjustments with a single guitar are always a bit hit or miss relying on ear memory but I think I am getting to where I want to be.

I have found that I prefer the sound of partial coil cuts so that the by bypass filter works only on one coil when the pup is wired in parallel. See extract of my schematic. For simplicity PPs are shown as standard as opposed to convoluted CTS wiring. This wiring I think also gives improved sounds when both the coil swap and partial cut are engaged. Also I think I can hear a slightly sweeter sound iwith a small 0.05 cap added in series to the resistor.

I am at the moment using 500k pots( cheap imports I had lying around) as resistors to find a value I like . Current favourite values seem to be around 375 ohm for the bridge and 210 for the neck. Single resistors of similar values will eventually be fitted to neaten things up under the hood.

My electrical theory is very limited and I would be interested to learn from some one more knowledgeable what is the difference in terms of current flow of wiring a partial coil cut as normal (as in fig 1) or of how I have wired it (fig 2) . Also what is it that happens to the “frequency filter” when you wire a small cap in series with a resistor as I have done. I was intrigued out of curiosity to try resistor and cap in parallel as per the de mud mod but never got around to it. If anybody can tell me the likely result in a partial ciol cut situation it would be appreciated.

Hi GString,

I've continued to ponder your wiring ideas, and I have a question. When you combine two coils of the same humbucker pup in this way (in parallel but with one coil partially cut), i would suspect that the resultant sound could have some Strat Position 2 type quack present? Of course, the amount of quack would depend on how much the 2nd coil is cut, i.e. the value of the resistor. Would you mind letting me know if my suspicion is correct and what resistor & cap values seemed to produce the highest amount of quack?

 

[Artie]

PM Artie, Freefrog, or GuitarDoc and ask them to take a look at this thread. They might have simply missed it.

I'm looking at it now. But need a bit more coffee to interpret this one.

BTW, Jack. I did look at that HCP pot thing, but that's one of those things that I'd have to buy, and hold in my hand, to figure out accurately. Sorry if I didn't respond. Got lot's of "irons-in-the-fire" right now. But I'll look at it, and this thread, again.

Artie

Edit: Didn't see freefrog's response when I posted.