Blade Style Pickup - Ceramic Magnet Orientation

[rjb]

I would say your latest assembly is close to the original T40 design (PV started with ferrite blades and switched over to steel blades with a central magnet). So the original spec of 3750 turns would be a good starting point. The only issue would be if your magnets are shorter than the originals and you couldn't fit 3750 turns between the flats.

I am looking to match the resistance, correct/

You would be looking to match the inductance- but we don't know that. A short, fat coil will have higher inductance than a tall, skinny coil with the same number of turns. But without having the dimensions of the PV ferrite-blade T40s, its all moot; the only alternative is to tune by ear and taste.

[Freekmagnet]

I would say your latest assembly is close to the original T40 design (PV started with ferrite blades and switched over to steel blades with a central magnet). So the original spec of 3750 turns would be a good starting point. The only issue would be if your magnets are shorter than the originals and you couldn't fit 3750 turns between the flats.


You would be looking to match the inductance- but we don't know that. A short, fat coil will have higher inductance than a tall, skinny coil with the same number of turns. But without having the dimensions of the PV ferrite-blade T40s, its all moot; the only alternative is to tune by ear and taste.

Hey Freek, if you can give the bobbin core dimensions, maybe we can do some calculations.
Inside Bobbin core , Length, width, Height, Flange ?
T

OK, so inductance is determined by the shape of the coil. A taller coil = more focused than a shorter and fatter coil. That's pretty logical. We're not going measure that here, but if we had a visual reference, we could try to match it. The amount of winds affects the inductance only in the sense that more winds make the coil fatter. If we were trying to really ape the overall character of the pickup, we'd be looking at inductance, or the size and shape of the coil, correct?

I'm kinda just repeating what you posted just to organize my thoughts.

Back to my original question, the coil winder is essentially there to help us determine how many winds it would take to create a certain resistance given the size and shape of the bobbin, or vice versa. Because a pickup needs a sufficient amount of resistance to make noise, we can take a resistance measurement, say 2.8K like the PV, and use that to determine how many winds we're going to wrap around the bobbin to make our coil. Since in this case, I have yet to determine what I'm actually going to build, I'm using that resistance measurement to determine a starting point for the amount winds around the bobbin in order to make a functioning coil.

Am I kind of on the right track?

Thanks.

[Jason Rodgers]

I don't think you're going to have any trouble getting 3750 turns on those bobbins. Using the 1/8" width of the magnets as a measure, I'm guessing you have about 1/4" of flange and about 3/8" inside height? My pickups had a little less flange and a little more height, but I got 7000 turns with 42awg on the bridge coils.

[Freekmagnet]

I don't think you're going to have any trouble getting 3750 turns on those bobbins. Using the 1/8" width of the magnets as a measure, I'm guessing you have about 1/4" of flange and about 3/8" inside height? My pickups had a little less flange and a little more height, but I got 7000 turns with 42awg on the bridge coils.

That's pretty close - it's more like 3/8" X 3/8" X 3/8".

I'm going to wait until I get those Mojotone bobbins in the mail before I start winding.

[rjb]

The amount of winds affects the inductance only in the sense that more winds make the coil fatter.

No, it's more complicated than that. The inductance is proportional to the the square of the number of turns, but is also influenced by the coil geometry. Here's the formula for an "ideal" solenoid (which doesn't really apply here because a pickup coil around a ferrite blade is more like a short air coil). Inductance of a solenoid
On second thought, forget I mentioned inductance.

Because a pickup needs a sufficient amount of resistance to make noise,

No. Resistance is probably the least important pickup spec. Manufacturers cite it because it's easy to measure.
The pickup needs a sufficient number of wire turns to induce a sufficient voltage.

we can take a resistance measurement, say 2.8K like the PV, and use that to determine how many winds we're going to wrap around the bobbin to make our coil. Since in this case, I have yet to determine what I'm actually going to build, I'm using that resistance measurement to determine a starting point for the amount winds around the bobbin in order to make a functioning coil.

Matching turns count will get you a lot closer than matching resistance will.

The coil estimator can tell you how much #42 wire will fit on your bobbin- but since we know the bobbin will hold a lot more than 3750 turns, I'm not sure how that helps you.

Knowing the resistance can be helpful in comparing pickups with the same geometry and wire gauge.
Say you know that T40 neck pickups are wound with 3750 turns of #42 wire and have a DCR of 2.8Kohm.
Say (for example) that T40 bridge pickups use the same bobbins and are wound to 3.2Kohm of #42 wire.
You can use ratios to estimate that the bridge pickups are wound with about (3.2/2.8) * 3750 = 4286 turns.

[rjb]

Just thought you might be interested in this treatise by Hartley Peavey

http://peavey.com/monitor/pvpapers/Chapter5.pdf

If you compare a typical magnet loaded single coil pickup to a typical induced magnet single coil pickup,you will find that the induced magnet has a fuller “bell like” quality, while the magnet loaded pickup tends to have an “edgier” Hi-Fi type response. There are reasons for this, which are complex and probably too technical for this “primer” on guitar pickups. Generally speaking, magnet loaded pickups tend to have “higher fidelity” and have more “bite” or edge than so-called “induced magnet” pickups. Most hum canceling pickups tend to be of the “induced magnet” type, while most single coils, tend to be of the “magnet loaded” type.

HP's terminology:
"magnet loaded" pickup means one with magnets as poles; "induced magnet" means with magnetized steel poles.

PV started with "magnet loaded" humbucking pickups in T-40s and T-60s, but switched to "induced magnet" pickups.

[Freekmagnet]

No, it's more complicated than that. The inductance is proportional to the the square of the number of turns, but is also influenced by the coil geometry. Here's the formula for an "ideal" solenoid (which doesn't really apply here because a pickup coil around a ferrite blade is more like a short air coil). Inductance of a solenoid
On second thought, forget I mentioned inductance.


No. Resistance is probably the least important pickup spec. Manufacturers cite it because it's easy to measure.
The pickup needs a sufficient number of wire turns to induce a sufficient voltage.


Matching turns count will get you a lot closer than matching resistance will.

The coil estimator can tell you how much #42 wire will fit on your bobbin- but since we know the bobbin will hold a lot more than 3750 turns, I'm not sure how that helps you.

Knowing the resistance can be helpful in comparing pickups with the same geometry and wire gauge.
Say you know that T40 neck pickups are wound with 3750 turns of #42 wire and have a DCR of 2.8Kohm.
Say (for example) that T40 bridge pickups use the same bobbins and are wound at 3.2Kohm of #42 wire.
Then you can use ratios to estimate that the bridge pickups are wound with (3.2/2.8) * 3750 = 4286 tuIrns.

Cool, Thx. That actually clears up a lot of confusion. I was vaguely cognizant of the notion that resistance the ultimate red herring of pickup tone, largely brought about by decades of incessant marketingspeak, however it's good to know that regardless, measuring resistance is a helpful reference tool.

As I draw nearer to getting my act together with this project, I'm definitely going to mess around with that inductance estimator. That thing is cool!

I ordered bobbins and magnets last night from Mojo as well as some T-Bird covers. I am going to mess around with those a little before I do a wind. The T-Bird is kind of a standard route and I wouldn't have to make the cover myself. I could make a tray for T40 pickup, but I'd have to buy more tools and supplies which don't feel like doing right now.

Thanks for posting that Peavey bit, too. That was cool.

[big_teee]

It's not an inductance estimator.
It is more of a resistance to turns estimator.
It is to estimate what resistance you will have with a given turn count with a certain size bobbin.
The dimensions of the bobbin determines how many turns will equal what resistance.
Tension and scatter is also a determining factor.
You'll figure it out.
T

[David King]

WHere resistance measurement is very useful is to determining if you have any internal shorts inside your coils. Internal shorts are caused by winding with too much tension and/or when the wire insulation is too thin or weak and layers of wire are touching and shorting against each other. The other way to determine this problem is when your pickups suddenly sound like shit.

[Mike Sulzer]

Just thought you might be interested in this treatise by Hartley Peavey

http://peavey.com/monitor/pvpapers/Chapter5.pdf

If you compare a typical magnet loaded single coil pickup to a typical induced magnet single coil pickup,you will find that the induced magnet has a fuller “bell like” quality, while the magnet loaded pickup tends to have an “edgier” Hi-Fi type response. There are reasons for this, which are complex and probably too technical for this “primer” on guitar pickups. Generally speaking, magnet loaded pickups tend to have “higher fidelity” and have more “bite” or edge than so-called “induced magnet” pickups. Most hum canceling pickups tend to be of the “induced magnet” type, while most single coils, tend to be of the “magnet loaded” type.

HP's terminology:
"magnet loaded" pickup means one with magnets as poles; "induced magnet" means with magnetized steel poles.

PV started with "magnet loaded" humbucking pickups in T-40s and T-60s, but switched to "induced magnet" pickups.

Complex? Too technical? Perhaps, but these reasons are not mysterious as he makes them seem; it is just a matter of different conductivity and permeability. The difference is that the magnets result in a resonance with higher frequency and Q. This is not high fidelity. Fidelity to an original does not apply to electric guitars: there is no original sound to reproduce. You could say that the "fidelity" here has something to do with reproducing the vibrations of the string accurately, but how does a higher Q resonance do that? Peavy confuses his own preferences with reality. OK, that trait helps make a good salesman.

[SpareRibs]

Complex? Too technical? Perhaps, but these reasons are not mysterious as he makes them seem; it is just a matter of different conductivity and permeability. The difference is that the magnets result in a resonance with higher frequency and Q. This is not high fidelity. Fidelity to an original does not apply to electric guitars: there is no original sound to reproduce. You could say that the "fidelity" here has something to do with reproducing the vibrations of the string accurately, but how does a higher Q resonance do that? Peavy confuses his own preferences with reality. OK, that trait helps make a good salesman.

Hello,
With all due respect, I think in the article he was trying to get the point across to people that may not have an engineering degree. It seems to convey the idea without going into elaborate detail.
I think I understand from the point of, comparing Fender single coils with magnetized slugs, to Gibson Humbuckers with the magnet between the two coils, and the screws and slugs being non magnetic. The Fender sound is quiet a bit more shrill and pronounced, while the Gibson is more mellow.
That seems to be the point being made in the Peavy publication referred to.

[Mike Sulzer]

Well, you are a better person than I am, being willing give the guy a break and assume he has the good motives of a technically competent, but helpful person, but his use of pseudo technical terms (magnet loaded, induced magnet) would indicate otherwise. What is a non-technical person to make of them? Furthermore, the terms carry no general meaning as he implies. For example, you can use soft magnetic ferrite cores with essentially no conductivity (and no permanent magnetism), but low or high permeability, and induce the magnetism in them with any magnet you like, and get very high Q over a range of resonant frequencies. Just not one of the two main things that caught on.

Hello,
With all due respect, I think in the article he was trying to get the point across to people that may not have an engineering degree. It seems to convey the idea without going into elaborate detail.
I think I understand from the point of, comparing Fender single coils with magnetized slugs, to Gibson Humbuckers with the magnet between the two coils, and the screws and slugs being non magnetic. The Fender sound is quiet a bit more shrill and pronounced, while the Gibson is more mellow.
That seems to be the point being made in the Peavy publication referred to.

[SpareRibs]

Well, you are a better person than I am, being willing give the guy a break and assume he has the good motives of a technically competent, but helpful person, but his use of pseudo technical terms (magnet loaded, induced magnet) would indicate otherwise. What is a non-technical person to make of them? Furthermore, the terms carry no general meaning as he implies. For example, you can use soft magnetic ferrite cores with essentially no conductivity (and no permanent magnetism), but low or high permeability, and induce the magnetism in them with any magnet you like, and get very high Q over a range of resonant frequencies. Just not one of the two main things that caught on.

Hello,
Given the guys tendency to be deceptive and misleading would you be willing to clarify a few points such as, explaining just exactly what magnetism is, and its overall effect on creating inductance ?? In a thousand words or less.

[John Kolbeck]

Hello,
With all due respect, I think in the article he was trying to get the point across to people that may not have an engineering degree. It seems to convey the idea without going into elaborate detail.

Receiving no information is better than receiving wrong information.

Suppose you're learning math, and you ask "how do I multiply two times two, and what is the result?" and I reply "you get the same result if you add two plus two, just do that", you might jump to the conclusion that addition and multiplication are the same thing. You get a quick answer that solves the immediate problem, but you're worse off in the long run for having received inaccurate information.

[big_teee]

It seems that most of the debate is with guys that do very little or no winding!
The PV book was just trying to get some elementary points across.
No harm, no foul!
T