Phase issues and epoxy stripping

[Kinetic Bass]

Can someone please clarify phase issues:

I have old Ken Smith JJ split coils (Ceramic pups), had them wired with V,V,T with a push/pull on the bridge to act as series/ parallel.

So first question is, if bridge vol is off then in series mode the bass is silent, is that correct wiring since bridge goes into neck under series connection.

If I wanted to put these JJ side by side like MM, does the issue of out phase come into play here because something happens there with magnetic field or is it an issue of wiring and out of phase is only because both pickups are wired to the same output jack so when they sum up it’s out of phase that should mean their position side by side has no effect on phase.

Or is it both, position and wiring has an effect on phase?

If position does effect phase, what happens if they are spaced a part by only ¼”, kind of like Dingwall 3 middle pickups but spaced a bit more, so if I buy another set can I do three pickups in the middle spaced only ¼” part.

Where does turning pickups 180 degree come into play vs. spacing them a part a bit vs. switching lead wiring hot/ground to change the phase?

What happens if I took a single split coil and rotated one of the coils, or moved it ¼” like a P-Bass position?

These are heavily molded in black epoxy, so can’t rotate individual coils or move them like P-Bass.

Is there a safe solution to remove it from epoxy without damage? I saw a guy on youtube boil a set in water for few minutes, the epoxy gets soft then start cutting and peeling piece by piece with a knife

Here it is ( 6:30 minute mark):



Is that safe, or there is a better way, I would suspect soaking in any acidic-based solution is not safe at all.

Cheers.

 

[ctmullins]

Re: series wiring - yes, volume acts as master volume, so that’s normal.

Re: your discussion of phase - what problem are you trying to solve? There shouldn’t be any reason at all to try to disassemble these pickups, and you would likely fatally damage them anyway.

Not sure what you mean by phase. A match neck/bridge pair of pickups are typically Reverse Wound Reverse Polarity (RWRP), which is what makes them hum-cancelling. But their outputs are still in phase. If they were out of phase they would sound absolutely terrible and you would be driven to take up basket weaving instead of bass playing.

This is not affected by position.

This is not affected by rotating the pickup 180 degrees.

But please, explain more what you’re trying to do.

 

[Kinetic Bass]

I want to move the position of each coil independently, so if I get another pair of split coils and can take it out of the case/ epoxy, I can position them as I please, image attached of one example.

 

[sunbeast]

Can someone please clarify phase issues:

I have old Ken Smith JJ split coils (Ceramic pups), had them wired with V,V,T with a push/pull on the bridge to act as series/ parallel.

So first question is, if bridge vol is off then in series mode the bass is silent, is that correct wiring since bridge goes into neck under series connection.

If I wanted to put these JJ side by side like MM, does the issue of out phase come into play here because something happens there with magnetic field or is it an issue of wiring and out of phase is only because both pickups are wired to the same output jack so when they sum up it’s out of phase that should mean their position side by side has no effect on phase.

Or is it both, position and wiring has an effect on phase?

If position does effect phase, what happens if they are spaced a part by only ¼”, kind of like Dingwall 3 middle pickups but spaced a bit more, so if I buy another set can I do three pickups in the middle spaced only ¼” part.

Where does turning pickups 180 degree come into play vs. spacing them a part a bit vs. switching lead wiring hot/ground to change the phase?

What happens if I took a single split coil and rotated one of the coils, or moved it ¼” like a P-Bass position?

These are heavily molded in black epoxy, so can’t rotate individual coils or move them like P-Bass.

Is there a safe solution to remove it from epoxy without damage? I saw a guy on youtube boil a set in water for few minutes, the epoxy gets soft then start cutting and peeling piece by piece with a knife

Here it is ( 6:30 minute mark):



Is that safe, or there is a better way, I would suspect soaking in any acidic-based solution is not safe at all.

Cheers.

There are multiple considerations of "phase" to consider-

180-degree out-of-phase pickups will cancel substantial parts of the low-end of the combined sound (either in parallel or in series) causing a very thin sound that most bassists would not find usable. Fixing that is usually just a matter of reversing the + and - of one of the two pickups. Since your pickups are designed to work together, you don't need to worry about 180-degree phase issues since they will already be wired "in-phase" with each-other.

The other phase consideration is frequency-dependent phase- this will happen anytime you have two pickups or two coils on at the same time on different parts of the same string (again, will have an effect regardless of the pickups being in series or parallel with each-other). The relative location of the two pickups to each-other will change the relative phase and amplitude of different frequencies that will be additive with each-other or subtractive with each-other between the two pickups, so the overall tone will change by moving the pickups closer or farther away from each-other due to different frequency wavelengths and where the pickups sit under them, but there is no way to eliminate some degree of frequency-dependent phase-cancellation. Usually when the two coils/pickups are very close together you will notice significant upper-midrange cancellation, the more you separate them the more they will tend to sound "scooped" due to notches in the more middle midrange frequencies (in reality you are getting lots of little peaks and notches at different frequencies).

A P-bass pickup doesn't have either type of phase issue because the two coils are sensing entirely different strings so there is no shared signal between the two coils.

 

[ctmullins]

I want to move the position of each coil independently, so if I get another pair of split coils and can take it out of the case/ epoxy, I can position them as I please, image attached of one example.

Why?

 

[sunbeast]

I want to move the position of each coil independently, so if I get another pair of split coils and can take it out of the case/ epoxy, I can position them as I please, image attached of one example.

As cool as the idea might sound in theory, a bunch of standard-output magnetic pickups along a string like that can start to affect the way the string vibrates (if you want to do something like this you are probably better off with active pickups like EMGs that have relatively less magnetic flux, but even then I would guess the many would become an issue). Also, the offset arrangement of a P coil for example is only a part of the way it sounds like it does- it is also about the coil shape and winding as well as the magnets. Taking the coils out of a split J pickup and offsetting them is going to sound different than a P because of the different shaped coils- really all you'll do is create more frequency imbalance between the two halves while retaining most of the general tonal characteristics of the pickup as it was originally (the thinner sounding D and G strings and thicker sounding E and A of a P-bass pickup offset can be either a feature or a bug of a P-bass depending on your personal approach).

 

[Kinetic Bass]

We are back to square one, I asked if moving pickups changes the phase or not based on being close to each other or not. I don't like the bright tone of D&G strings and in general chasing specific tone, not a P or a scooped J tone nor MM tone, so moving things around until I find optimal position with existing pickups is a cheap way. By the way Ken Smith JJ pickups were produced to be used with a pre-amp.

 

[ctmullins]

The phase of a pickup is “locked in” when the pickup is manufactured. If you want/need to invert the phase once it’s installed into an instrument you can swap the hot and ground wires (but also will need to keep any shielding connected to ground).

Two (or more) pickups in an instrument will also produce frequency cancellations in certain frequency ranges, based on how close they are to one another. This isn’t technically a “phase” phenomenon though. But is that what you’re concerned about?

There’s nothing to be gained by attempting to split your existing pickups. If you want to experiment, buy some cheap P (or mustang) pickups and tinker with those. You can install your Ken Smith J pickups on a slant to address any frequency response issues.

 

[sunbeast]

The phase of a pickup is “locked in” when the pickup is manufactured. If you want/need to invert the phase once it’s installed into an instrument you can swap the hot and ground wires (but also will need to keep any shielding connected to ground).

Two (or more) pickups in an instrument will also produce frequency cancellations in certain frequency ranges, based on how close they are to one another. This isn’t technically a “phase” phenomenon though. But is that what you’re concerned about?

There’s nothing to be gained by attempting to split your existing pickups. If you want to experiment, buy some cheap P (or mustang) pickups and tinker with those. You can install your Ken Smith J pickups on a slant to address any frequency response issues.

Frequency-dependent cancellations are also related to the different phase of those frequencies as they cross each of the different pickups. Very much “phase”, just rarely a 180-degree difference like the electrical phase of two reversed pickups.

 

[walterw]

If I wanted to put these JJ side by side like MM, does the issue of out phase come into play here

short answer is no

if they're in phase where they sit now they're still in phase if you move them

 

[Kinetic Bass]

The phase of a pickup is “locked in” when the pickup is manufactured. If you want/need to invert the phase once it’s installed into an instrument you can swap the hot and ground wires (but also will need to keep any shielding connected to ground).

Two (or more) pickups in an instrument will also produce frequency cancellations in certain frequency ranges, based on how close they are to one another. This isn’t technically a “phase” phenomenon though. But is that what you’re concerned about?

There’s nothing to be gained by attempting to split your existing pickups. If you want to experiment, buy some cheap P (or mustang) pickups and tinker with those. You can install your Ken Smith J pickups on a slant to address any frequency response issues.

Is this interference or cancellation predictable on the frequencies, like alnico against ceramic would eliminate high frequencies, or ceramic against ceramic would eliminate something else?

Can I EQ that bad behavior, for example if I had a dedicated volume and dedicated tone control on each split coil with different cap value on each tone is that enough to EQ it out.

How do manufacturers solve this problem, for example Dingwall has 3 pickups in a row side by sideso ther must be some cancelaltion there vs P pickup which is differnt problem, you are not dealing with the same strings or same frequencies in lateral direction.

What about taking it further, I’ve never seen a dual on board pre-amp set up, where one amp or IC chip is for E,A strings, and one with different color or character with more darker tone for D,G string.

Also do all manufactures of split coils use the same phase direction so if I paired two pickups from different brands I know the output is not the same, but logic would say phase direction must be the same since we are dealing with the same strings and frequencies per string allocation.

 

[sunbeast]

Is this interference or cancellation predictable on the frequencies, like alnico against ceramic would eliminate high frequencies, or ceramic against ceramic would eliminate something else?

Can I EQ that bad behavior, for example if I had a dedicated volume and dedicated tone control on each split coil with different cap value on each tone is that enough to EQ it out.

How do manufacturers solve this problem, for example Dingwall has 3 pickups in a row side by sideso ther must be some cancelaltion there vs P pickup which is differnt problem, you are not dealing with the same strings or same frequencies in lateral direction.

What about taking it further, I’ve never seen a dual on board pre-amp set up, where one amp or IC chip is for E,A strings, and one with different color or character with more darker tone for D,G string.

Also do all manufactures of split coils use the same phase direction so if I paired two pickups from different brands I know the output is not the same, but logic would say phase direction must be the same since we are dealing with the same strings and frequencies per string allocation.

Split-coils don’t even need to be in the same electrical phase to work and be humcancelling unlike side-by-side coils. Mustang Bass pickups for example were traditionally two identical coils with one wired out of phase with the other- the noise is induced into the coil, so wiring the two coils out of phase cancels the noise and because each coil only senses different strings from the other there is no phase cancellation of the string signal even though the E and A are out of phase with the D and G.

Pickups from different manufacturers are not always wound in the same phase- there is no set standard for winding so usually manufacturer’s themselves just have their own internal standard but sometimes if you mix pickups with other manufacturers you will find that two of the pickups are electrically out of phase and creating a thin sound. In many cases fixing this is just a matter of reversing the + and - wires of one of the pickups, but some pickups with internal shielding have that shielding tied to the - wire and so either will require extra work to reverse the phase or won’t practically be able to do it at all (if the pickup is epoxy potted for example).

The frequency-dependent phase-cancellation that happens when you have two pickups sensing the same string in different locations is simply a part of the recipe of the “2 pickup” sound- it’s the reason Jazz Basses have a pronounced midrange scoop when both pickups are turned up for example, and part of the reason that a guitar humbucker (traditionally with 2 coils sitting right next to each-other) has the darker tone that it is known for. It is simply a reality and not really something that can be fixed with EQ or otherwise because the frequency nodes are actually different on different strings. You could create a crossover wherein one pickup is providing the lows and the other midrange and highs, which is a cool idea- because then there is little shared frequency to get phased out.

It is possible to mathematically model the frequency interaction between two pickups, but rarely done.

 

[Passinwind]

You could create a crossover wherein one pickup is providing the lows and the other mids and highs, which is a cool idea- because then there is little shared frequency to get phased out.

Yep, or bass and mids on one side and just treble on the other, which is my current squeeze.

 

[sunbeast]

Yep, or bass and mids on one side and just treble on the other, which is my current squeeze.

I have done it with an ACG/East filter preamp, since they have an HPF section that has an internal blend to choose where it is tapping from- sometimes I’ll solo the neck pickup but have the HPF tapped at the bridge only so I can make the neck pickup LPF really fat then roll in only the highs from the bridge pickup (or even vice-versa). I’d love a more customizable version, I really need to dig into one of your projects!!

 

[Kinetic Bass]

Well, in this video, the guy stacked them all side by side and I don't hear anything very odd unless it's all of them summed up then it gets very dull:



What would be the most simple cross over (do you have a schematic) is it 1st order, or complex 4th order and does it need an inductor as well for?

 

[Passinwind]

I have done it with an ACG/East filter preamp, since they have an HPF section that has an internal blend to choose where it is tapping from- sometimes I’ll solo the neck pickup but have the HPF tapped at the bridge only so I can make the neck pickup LPF really fat then roll in only the highs from the bridge pickup (or even vice-versa). I’d love a more customizable version, I really need to dig into one of your projects!!

I'd be happy to help you work on your own spin. I am out of instruments and time to do much more experimentation on my own, and the luthiers I work with all tend to be more interested in the same old "conventional" preamp formats. Not that there's anything wrong with that...