Paf offsets

[Steve Conner]

Spence can explain about dielectric constant since he's an instrumentation engineer as well as a pickup maker.

[Joe Gwinn]

We've had someone mention the dielectric thing but with no explanation how how it would relate to electromagnetic/audio coils. So what's the effect of self capacitance? So how is this measured, what kinds of units are used? This is a missing bit of information for me. And its probably a MAIN reason we use formvar and plain enamel wire, yes because it's what was used but yes its because you can hear the difference in wire coatings, it's subtle but its there and I think the dielectric property is a big influence here. Tell me more....

The main electrical properties of the coating on magnet wire are thickness and dielectric constant, as Steve Connor mentioned. These together affect the self-capacitance of the coil, which will be proportional to dielectric constant and inversely proportional to coating thickness.

Thickness also affects the inductance of the coil, by changing both the amount of physical space that a coil of a specified number of turns takes, and its shape. The computation of the inductance of non-circular thick, short coils (like those in pickups) is complex, but in general, for a specified number of turns, the thicker (in the winding depth direction) the coil the lower the inductance, and the shorter (in the traverse direction) the higher the inductance, but the strongest effect is that the larger the open area (where the magnets or slugs go) the larger the inductance.

Apparently, the slipperyness of the coating also matters. I recall people saying that one could wind more turns of plain enamel than other kinds becasue the plain enamel wire was smooth and slippery, and so the turns snuggled together more closely.

Self-resonant frequency is determined by the above inductance and self-capacitance. At least in isolation. In practice, the coil self-capacatance is swamped by the capacitance of the cable from guitar to amplifier, so the resonant frequency is set by the inductance and the sum of cable and coil capacitance.

The easiest way to measure self-capacitance is to measure the inductance at 1,000 Hz (this being well away from resonance), then measure self-resonant frequency, and compute the capacitance necessary to resonate the measured inductance at the measured frequency.

The dielectric constant of all magnet wire insulations is about equal, so in practice the thickness of the coating will be the controlling variable. Thus the use of double coatings in some pickups. So, one way to experimentally explore the effect of coating thickness on tone is to compare a pickup wound with single build with the same kind of pickup wound instead with double build magnet wire. One could also try triple build.

[Spence]

Spence can explain about dielectric constant since he's an instrumentation engineer as well as a pickup maker.

Um, well I'd prefer to talk about the dielectric medium and how it's effected by an electric field and it's ability to polarize in response to the field ie.. permittivity.

Big subject in relation to guitar pickups. When you add other factors into the equation like scatter patterns and potting compounds it gets even hairier.

I have done A/B tests between heavy build PE and heavy build Formvar. They sound different to me.

[Possum]

insulation types...

"The dielectric constant of all magnet wire insulations is about equal".......this doesn't sound right. If plain enamel is basically some kind of varnish, as probably is formvar, I would think the poly/nylon type insulations versus varnish would be noticeably different in effect. I mean its noticeable to a player. The poly wire, Lollar said its best..is "splashy" sounding, modern, the enamels, formvars are more constrained sounding, more vintage, defined. The poly wires ARE more slippery and you can get alot more winds on a coil than the varnish types, though I'm not so sure about the REA magnet PE its seems more slippery than the plain enamels we used to get. Again, how is this dielectric effect expressed, is there a term for it, or units of measurement? And Spence made a good point, how can you factor in say wax potting versus shellac, or lacquer or whatever that gunk that WSC uses, some kind of acrylic stuff?

[Joe Gwinn]

"The dielectric constant of all magnet wire insulations is about equal".......this doesn't sound right. If plain enamel is basically some kind of varnish, as probably is formvar, I would think the poly/nylon type insulations versus varnish would be noticeably different in effect. I mean its noticeable to a player. The poly wire, Lollar said its best..is "splashy" sounding, modern, the enamels, formvars are more constrained sounding, more vintage, defined. The poly wires ARE more slippery and you can get alot more winds on a coil than the varnish types, though I'm not so sure about the REA magnet PE its seems more slippery than the plain enamels we used to get. Again, how is this dielectric effect expressed, is there a term for it, or units of measurement? And Spence made a good point, how can you factor in say wax potting versus shellac, or lacquer or whatever that gunk that WSC uses, some kind of acrylic stuff?

Just becuase the pickups made with different insulation on the wire sounds different doesn't prove that the dielectric constants are the cause. Changing the inductance will also have a big effect.

Wax has about the same dielectric constant as plastic insulations, both being higher than air, so waxing a coil should raise its self-capacitance a bit. But not by much - geometry is everything.

As for the definition of dielectric constant, Google for "parallel plate capacitor" to get many physics lessons. The most basic definition is an experiment: build a parallel-plate capacitor having plates of large area but small separation between the plates. Put this capacitor in a vacuum, and measure the capacitance. Then, put the material of interest between the plates, and measure the capacitance again. This value will be larger than the vacuum value. The dielectric constant is the ratio of the capacitance with material to that with vacuum. So, vacuum has a dielectric constant of exactly one, air is slightly greater than one, many oils and plastics are approximately 3, glass is 6 or 7, and so on.

Wikipedia also has an article: http://en.wikipedia.org/wiki/Capacitor.

[NightWinder]

When I started making buckers I used a huge offset, like 1.5K almost, I didn't notice any more noise than a regular humbucker, but I'm not that picky either. It would make sense to me that you could get away with alot of mismatch since you are only sensitive mostly to 60 cycle hum which is pretty low frequency and easily cancelled with any mismatch. My theory anyway....

Jesus!!! 1.5k!! Almost reinventing the UNbucker!!! What was that pickup going to be tested in?

[Spence]

Just becuase the pickups made with different insulation on the wire sounds different doesn't prove that the dielectric constants are the cause. Changing the inductance will also have a big effect.

Wax has about the same dielectric constant as plastic insulations, both being higher than air, so waxing a coil should raise its self-capacitance a bit. But not by much - geometry is everything.

As for the definition of dielectric constant, Google for "parallel plate capacitor" to get many physics lessons. The most basic definition is an experiment: build a parallel-plate capacitor having plates of large area but small separation between the plates. Put this capacitor in a vacuum, and measure the capacitance. Then, put the material of interest between the plates, and measure the capacitance again. This value will be larger than the vacuum value. The dielectric constant is the ratio of the capacitance with material to that with vacuum. So, vacuum has a dielectric constant of exactly one, air is slightly greater than one, many oils and plastics are approximately 3, glass is 6 or 7, and so on.

Wikipedia also has an article: http://en.wikipedia.org/wiki/Capacitor.

What vacuum. I have tried to make, market and play in a vacuum but I ran out of breath.
Back in the real world where thankfully vacuums are not so life threatening, Wikepedia has a very nice section about permittivity:

http://en.wikipedia.org/wiki/Permitt...x_permittivity

Complex permittivity and dielectric absorption processes seem like a good place to start. Not quite a simple as saying all coatings are equal.

[Possum]

yum bucker

hey I WANTED them to be as close as to single coil sound as I could get :-) when I started making buckers I was forced at gun point to do it, I hated those freaking muddy horrible things, probably because of all those DeeMarzee-ohhhhs I ran into in the 80s. Only in the last year was I shocked to find out that winding both coils didn't make them quite as muddy as I thought they would go. Remember the very first PAF had two slug coils and sounded like a single coil, then their sales guys demanded adjustable screws so they'd have another selling point, and the legend was born.......

[Joe Gwinn]

What vacuum. I have tried to make, market and play in a vacuum but I ran out of breath.

But, it's worth it, for Science. Even if your blood boils.

Back in the real world where thankfully vacuums are not so life threatening, Wikepedia has a very nice section about permittivity:

http://en.wikipedia.org/wiki/Permitt...x_permittivity

Complex permittivity and dielectric absorption processes seem like a good place to start. Not quite a simple as saying all coatings are equal.

Whuff.. better to keep it simple. Note in the diagram in the Wiki article that the action starts at a gigahertz. I know that you young'uns have better hearing than I , but don't you think that a gigahertz is a bit of a fish tale?

Seriously, I don't think it necessary for pickup makers to go quite this deep into the theory of dielectrics because the dissipation factor of actual wire varnish and potting wax at 10KHz and below is quite small, perhaps 1%, and is in any event swamped by that of the polyethylene dielectric of the coaxial cable from guitar to amplifier. Not to mention that due to the tone control in the guitar.

I've heard from the golden-ear HiFi folk that cables made with polyvinyl chloride (PVC) dielectric don't sound good. I've always wondered if this is true (as the dissipation constant of even PVC isn't all that high), or just another urban legend (or, more to the point, sales pitch).

The analog engineering community generally thinks it nonsense, but I've never done or heard of an A/B comparison with cables otherwise matched (especially for total capacitance). Changing the load capacitance has a dramatic effect on the tone, so if capacitance isn't matched, the experiment is worthless.

Actually, I have heard of an A/B comparison performed by an engineer (Bob Pease), but it was of speaker wire in a low-impedance circuit (16 ohms or so), not coax wire in a high-impedance audio circuit. The issue was if one needed to buy expensive super-dooper teflon-insulated gold-plated finely multistranded (even Litz) speaker wire, or would ordinary coarsely-stranded 12-guage or 10-guage AC power wire suffice. The result was that there was no detectable or audible difference in speaker circuits. So buy the cheap stuff.

[NightWinder]

Odd tidbits

hey I WANTED them to be as close as to single coil sound as I could get :-) when I started making buckers I was forced at gun point to do it, I hated those freaking muddy horrible things, probably because of all those DeeMarzee-ohhhhs I ran into in the 80s. Only in the last year was I shocked to find out that winding both coils didn't make them quite as muddy as I thought they would go. Remember the very first PAF had two slug coils and sounded like a single coil, then their sales guys demanded adjustable screws so they'd have another selling point, and the legend was born.......

funny, the paf remakes coming through for rewinds are relatively symetrical winds with a very small offset. The 2 slug coils are a great design, Im introducing 3 this yr. Relitively high ohm, 16k, 18k, and a 25k nuke. Oh, yeah Dave I reworked the "NUKE", and bumped it up a little. Same design, different offset, 2 different wire insulations......Sounds like an EMG 85 on freebased cocaine........You know me.....

[Spence]

Joe said....

"Whuff.. better to keep it simple. Note in the diagram in the Wiki article that the action starts at a gigahertz. I know that you young'uns have better hearing than I , but don't you think that a gigahertz is a bit of a fish tale?

Seriously, I don't think it necessary for pickup makers to go quite this deep into the theory of dielectrics because the dissipation factor of actual wire varnish and potting wax at 10KHz and below is quite small, perhaps 1%, and is in any event swamped by that of the polyethylene dielectric of the coaxial cable from guitar to amplifier. Not to mention that due to the tone control in the guitar."

Thank you. I've been suggesting we keep it simple for as long as I can remember.

[NightWinder]

So basically, joe says thats to much !! ashhhhh....I.ve wound past 30k, and retained highs....just for fun.

[David Schwab]

hey I WANTED them to be as close as to single coil sound as I could get :-) ... Remember the very first PAF had two slug coils and sounded like a single coil, then their sales guys demanded adjustable screws so they'd have another selling point, and the legend was born.......

Dave, I wind my humbuckers with both coils as close to the same as I can get ... but I just count turns, I only take an ohm reading when I'm done winding to make sure the coil is good.

I was surprised how bright the pickups came out. Very plucky, like single coils.

I don't know when everyone started saying humbuckers were muddy... I think you are right, with the over wound ones. They are warmer, but not really dark at all. But then you can't cal them glassy either.

[David Schwab]

Whuff.. better to keep it simple. Note in the diagram in the Wiki article that the action starts at a gigahertz. I know that you young'uns have better hearing than I , but don't you think that a gigahertz is a bit of a fish tale?

Seriously, I don't think it necessary for pickup makers to go quite this deep into the theory of dielectrics because the dissipation factor of actual wire varnish and potting wax at 10KHz and below is quite small, perhaps 1%, and is in any event swamped by that of the polyethylene dielectric of the coaxial cable from guitar to amplifier. Not to mention that due to the tone control in the guitar.

Joe, I'm going to start calling you the voice of reason! Yes, all these insulator specs are for very fussy high frequency applications... not audio frequency. At 1GHz the layout and thickness of the traces on your PC boards even matter!

I've heard from the golden-ear HiFi folk that cables made with polyvinyl chloride (PVC) dielectric don't sound good. I've always wondered if this is true (as the dissipation constant of even PVC isn't all that high), or just another urban legend (or, more to the point, sales pitch).

Have you seen these silly claims at Hi-Fi web sites about this $100 per once bottle of lacquer that when brushed on anything, is supposed to make it sound better! Speaker cones, wires, IC's, PC boards... just paint it on (with the provided brush in the cap) and instant better sound! And this is supposed to be the same "lost" lacquer formula that Stradivari used! Only I'm sure he used a spar vanish, and not lacquer.

Then there's a crazy person who sells this black lacquer that looks like nail polish, that he claims if you paint it on your plastic cased IC's, they will magically sound more analog and warm! I guess the ceramic cased IC's are OK. They claim the sound of the plastic case is bad. These same people peel the plastic wrap off their aluminum can capacitors for the same reason... they sound better with no plastic!

And don't get me started on those $500 wooden knobs for your hi-fi amplifier (the one that only has a volume knob... and a stepped resistor switch volume knob at that)! These people deserve to spend every cent they have on nonsense!

No one ever does blind controlled tests on these sites either! It's always: "we listened to it, and we think we hear more detail and imaging... "



I have great ears and these people give me a headache! lol

The analog engineering community generally thinks it nonsense, but I've never done or heard of an A/B comparison with cables otherwise matched (especially for total capacitance). Changing the load capacitance has a dramatic effect on the tone, so if capacitance isn't matched, the experiment is worthless.

Now, I bought a Monster cable years ago, and I think it sounded good... I could hear the difference from a cheap cable I was using. But when it broke last year (after almost 20 years use) I went and bought a good quality Spectraflex cable, and it sounds just as good.

Actually, I have heard of an A/B comparison performed by an engineer (Bob Pease), but it was of speaker wire in a low-impedance circuit (16 ohms or so), not coax wire in a high-impedance audio circuit. The issue was if one needed to buy expensive super-dooper teflon-insulated gold-plated finely multistranded (even Litz) speaker wire, or would ordinary coarsely-stranded 12-guage or 10-guage AC power wire suffice. The result was that there was no detectable or audible difference in speaker circuits. So buy the cheap stuff.

I built my own hi-fi cabinets once, and originally used the thin wire that came with the cross overs (maybe 22 gauge?). A year later I rewired the speakers with 12 gauge zip wire. I did one first, and compared the two cabinets. The one with the big wire was louder and crisper... it was like night and day.

So for something like speakers, increasing the wire gauge sure helps, but not the rest of the wire's construction.

[David Schwab]

So basically, joe says thats to much !! ashhhhh....I.ve wound past 30k, and retained highs....just for fun.

Mudbucker (sidewinder) territory!