need schematic for hum cancelling jazz bass pickups

[odyyiannis]

I think we have to rename the post to "JB noiseless alternatives"

[David Schwab]

Hi guess,
interesting, so options are:stacked coils (not so good alternatives for me),split coils (sound's good, but not 100% hum free particularly 5 strings),single string coils (not familiar with them),rails (as I hear David's Schwab's sidewinders they worth a check),hbs (?).
According to your opinion witch ones are the best alternatives ?

Stacks are OK. EMG Js are stacks. They are a little lower in volume, and tend to be very bright unless you over wind them. Split coils are very quiet. Listen to a P bass. There are a lot of Jazz pickups made that way. There's different ways to handle five strings, but for that reason I avoided split coils.

The one thing that is missing in most Jazz pickups is shielding, and the magnets are not grounded. We don't have to slavishly copy somewhat flawed designs from the past. You can improve upon them.

[odyyiannis]

stacks EMG are ok, most of bass players I know agree with that, but they don't want them in there basses.Split coils are ok to, but recently I send a 5string bass with Bart's split coils to a friend in Boston and he have a bud noise at his home (bud home electrics) without heaving the same noise with is fretless (Bart's humbuckers) at gig was all ok.

[odyyiannis]

The one thing that is missing in most Jazz pickups is shielding, and the magnets are not grounded. We don't have to slavishly copy somewhat flawed designs from the past. You can improve upon them.

an easy and effective way to ground mag's in jazz pickups is:before inserting magnets in forbon holes (bottom side),I use a reamer on each hole at half thickness of forbon,then I stick copper foil to the bottom, and I insert the magnets into the forbon.This way the copper foil goes into the holes with the magnets providing contact.Works always.
I have attached a photo witch I hope will appear.

[David King]

The 5 string splits aren't that hard to do, you just have to wind some extra turns on the 2 string segment and then make the magnets a little less powerful, probably the easiest way to do that is to make them a bit shorter. It probably makes sense to use a AWG 43 on that 2 string segment while you are at it just to have room for those extra turns. Id say the biggest problem with the splits is the phase shift of the strings on either side of the split which tends to knock the amplitude of those wrings down a bit. I'm pretty sure this is why Bartolini decided to go with 5 individual coils. You can't mix and match with other types of pickups however.

[David Schwab]

The 5 string splits aren't that hard to do, you just have to wind some extra turns on the 2 string segment and then make the magnets a little less powerful, probably the easiest way to do that is to make them a bit shorter. It probably makes sense to use a AWG 43 on that 2 string segment while you are at it just to have room for those extra turns.

I think that would make the 2 string part sound very different from the 3 string part. UNless that's what you want I wouldn't wind each half with different gauges of wire. As far as weaker magnets, I wouldn't do that either.

Id say the biggest problem with the splits is the phase shift of the strings on either side of the split which tends to knock the amplitude of those wrings down a bit.

Works fine on P basses and on split Jazz pickups. The two coils are out of phase, and have opposite magnetic polarity, so they are in phase with the strings.

I'm pretty sure this is why Bartolini decided to go with 5 individual coils. You can't mix and match with other types of pickups however.

Actually if you read the patent, he made smaller coils for two reasons. One was because the first Hi-A pickups had separate outputs for each string. The main reason is because smaller coils are clearer sounding.

From patent 3983778:

Since both the inductance and capacitance of a sensing coil vary linearly with its mean radius, replacing one coil by multiple small coils can reduce the impedance of the pickup system by a factor equal to the number of coils and raise the self-resonant frequency by a factor equal to the square root of the number of coils.

[odyyiannis]

Last weekend I make some tests with split coils and seems that David King have right.
In two identical coils,were inner leads are connected and outers goes to hot and ground, the ground side coil was brighter sounding than the hot side coil ?
I try to unwound some turns to get same treble respond but I've got different output.
I check Nordy's split-5, in Bridge p-up the difference was not so noticeable but in neck p-up it was,the 2 bass strings was far dark sounding.
I didn't try David's suggestion yet (shorter mags with more turns in dark sounding coil) but I am afraid that some other problem will appear like output or different sound character.

[David King]

Winding is the easy part but getting everything to match up is going to take a lot of experimentation as there don't seem to be any straightforward rules. Again the problem with split J 5s is that unless you limit your turns or go with much taller coils you won't have room for 42 wire between the 2 halves of your splits.
Others have managed to do splits that sound OK so it's possible. It may be that the 43 will actually brighten the tone, especially if it's a heavy insulation.

David Schwab, -alternating magnetic and wind polarities all the way across will also eliminate the unevenness of some adjacent strings being in or out of magnetic phase as found on typical split coils, this is less a problem on bass where the strings are further apart but definitely a problem on guitar. Bill Bartolini doesn't mention it in the patent but that doesn't make it less of a problem...

[Mike Sulzer]

Actually if you read the patent, he made smaller coils for two reasons. One was because the first Hi-A pickups had separate outputs for each string. The main reason is because smaller coils are clearer sounding.

From patent 3983778:

Since both the inductance and capacitance of a sensing coil vary linearly with its mean radius, replacing one coil by multiple small coils can reduce the impedance of the pickup system by a factor equal to the number of coils and raise the self-resonant frequency by a factor equal to the square root of the number of coils.

Right on part of it, but if you put the coils back in series in order to get a single output, then the inductance is back nearly to where it would be with a single coil. So you have not gained anything there. So it is not going to sound more clear.

[David Schwab]

So it is not going to sound more clear.

Have you tried it? It actually does. A perfect example is the Wal pickup. Each coil has 10,000 turns of 42, and reads about 2.5k. On the model I have here, there are eight coils, with each row of four in series. So each row is 10k. You would think it would be a dark sounding pickup, but even with all the coils in series it's thick yet bright sounding.

If you wound a two coil humbucker up to 20k with 42 AWG it wound be mud, as in the case of the Gibson EB-0 pickup.

So the only difference between these two are the multiple coils.

You can also hear it in the Bartolini pickups that use multiple coils.

[Mike Sulzer]

If the best you can do is to compare to a different pickup made by Gibson, I will stick with the obvious: if winding four small coils makes the inductance one quarter of a larger coil, then the inductance goes back up when you put them in series.

You quoted the Bartolini patent. This means that you believe what he wrote; that is, that four small coils, used individually, each have one quarter of the inductance of the larger coil (at least approximately), and you deduce that this makes the sound clearer. Then to be consistent, you have to believe that putting the coils back in series makes the inductance the same as the original larger coil, and that this is the less clear sound. You do believe that things have to be consistent, right?

By the way, while I have your attention, have you made any progress in understanding how the guitar string changes the reluctance of the magnetic pickup circuit without becoming magnetized? As far as physics is concerned, the only interaction is the alignment of the atomic currents, which is magnetization. If there is another form of interaction, the world wants to know!

Have you tried it? It actually does. A perfect example is the Wal pickup. Each coil has 10,000 turns of 42, and reads about 2.5k. On the model I have here, there are eight coils, with each row of four in series. So each row is 10k. You would think it would be a dark sounding pickup, but even with all the coils in series it's thick yet bright sounding.

If you wound a two coil humbucker up to 20k with 42 AWG it wound be mud, as in the case of the Gibson EB-0 pickup.

So the only difference between these two are the multiple coils.

You can also hear it in the Bartolini pickups that use multiple coils.

[David Schwab]

If the best you can do is to compare to a different pickup made by Gibson, I will stick with the obvious: if winding four small coils makes the inductance one quarter of a larger coil, then the inductance goes back up when you put them in series.

But it doesn't sound like two large coils. Does it? Oh wait, I will stick to the obvious too. You never tried it.

You said: "So it is not going to sound more clear." But that's not true. Explain why that is. As I pointed out in the example of the Wal pickup. It has eight coils wound with 10,000 turns of wire each. In series it's 20k, but does not sound like a pickup with two coils wound to 20k with the same gauge wire. This isn't conjecture on my part. I have the example pickups right here.

I asked if you tried it. Have you? If not, why are you commenting on it?

Mike, you like to state that the Bartolini patent is wrong, yet he's actually making pickups based on that, and they do what he said they do. So his goal was successful. If you care to build some pickups to demonstrate why he's wrong, be my guest.

Regarding the string being magnetized; as I have have said before, of course the string becomes temporarily magnetized. But that's swamped by the permanent magnet's field. You can see this by removing the permanent magnet and hearing that the pickup does not work very well. So the variable reluctance model makes more sense. Without the main magnet in the pickup, the magnetized string barely creates a signal. The fact that the string is magnetized is secondary to the string disturbing the permanent magnet's field.

[Mike Sulzer]

Single sgtring coils are one of the things I do. If you check back several (well, maybe, many) years in the MIMF archives, you will find a discussion where I described alternating the magnetic and electrical polarities and connecting the coils in series to make a strat bridge pickup, The inductances do add up, as they must. In this case, the total inductance was still below what most Strat bridge pickups have, and so it was a sort of clean sounding pickup (unless you added some capacitance in parallel). In every case I have tried, the sound of the series combination is exactly what you would expect from the total inductance. I think you need to make more careful A-B tests.

The steel used for strings retains very little magnetization. When you remove the magnet, it drops to a very small value immediately. That shows that the string magnetization is an essential feature of the pickup.

You are treating "reluctance" as if it is an independent property of the interaction of a magnetic material with a magnetic field, independent, that is, of the magnetization. It is not. It is a quantity that is defined as a matter of convenience in order ta allow a convenient analogy between electric and magnetic circuits.

So, do you see why I am asking you to show where reluctance comes from if not from the magnetization? If it is an independent property, it must have some physical basis. What is this?

But it doesn't sound like two large coils. Does it? Oh wait, I will stick to the obvious too. You never tried it.

You said: "So it is not going to sound more clear." But that's not true. Explain why that is. As I pointed out in the example of the Wal pickup. It has eight coils wound with 10,000 turns of wire each. In series it's 20k, but does not sound like a pickup with two coils wound to 20k with the same gauge wire. This isn't conjecture on my part. I have the example pickups right here.

I asked if you tried it. Have you? If not, why are you commenting on it?

Mike, you like to state that the Bartolini patent is wrong, yet he's actually making pickups based on that, and they do what he said they do. So his goal was successful. If you care to build some pickups to demonstrate why he's wrong, be my guest.

Regarding the string being magnetized; as I have have said before, of course the string becomes temporarily magnetized. But that's swamped by the permanent magnet's field. You can see this by removing the permanent magnet and hearing that the pickup does not work very well. So the variable reluctance model makes more sense. Without the main magnet in the pickup, the magnetized string barely creates a signal. The fact that the string is magnetized is secondary to the string disturbing the permanent magnet's field.

[David King]

My thinking is that the Barts sound cleaner because:
1) He's using Ceramic 8 magnets (at least on the bass pickups)
2) More of the wrap wire is closer to the magnets than on a single longer coil.
I don't know why having more wire closer to the iron poles increases brightness but it seems to.

I'd also argue with anyone who wants to argue that the single string coils have less DCR resistance (less wire length) overall per number of strings for a given number or turns than a traditional coil. Not sure what effect this will have, most likely just less overall capacitance, hence brighter.

[Mike Sulzer]

Less overall resistance, if it is significant, raises the Q of the resonance, giving a brighter sound.

If winding for the same number of turns gives a lower resistance, then winding for the same resistance could give more inductance and a less bright sound. So I think you need to know exactly what A and B are.

My thinking is that the Barts sound cleaner because:
1) He's using Ceramic 8 magnets (at least on the bass pickups)
2) More of the wrap wire is closer to the magnets than on a single longer coil.
I don't know why having more wire closer to the iron poles increases brightness but it seems to.

I'd also argue with anyone who wants to argue that the single string coils have less DCR resistance (less wire length) overall per number of strings for a given number or turns than a traditional coil. Not sure what effect this will have, most likely just less overall capacitance, hence brighter.