Paf offsets

[NightWinder]

Well. I seem to be having another fitshit. The Offset is been used in the past, but i have switched from A2 to A4. The A4 seems to want, and need a higher offset to tighten the lowend? This is QUack!! I am reaching about 600 turns differing.Nearly .80 off. The prototype was at .50ohm off, and the lowend just seemed to need tightening.......this is daunting.......

[David Schwab]

I wind my bass pickups with both coils the same... wouldn't mis-matching the coils bring out more top end?

I'm asking because I haven't messed with mismatching coils at all.

[Zhangliqun]

I wind my bass pickups with both coils the same... wouldn't mis-matching the coils bring out more top end?

I'm asking because I haven't messed with mismatching coils at all.

It does bring out a little more top end but not at the expense of the bass -- but that depends on which coil is hotter. Winding it with a hotter slug coil (on bridge pu) will simultaneously give you more beef (due to the lower freqs over the slug coil) AND more top end, and sweeter top end at that. Getting the ratio just right is the tricky part, but when you do, it's heaven.

On the other hand if you wind the screw coil hotter, it will really be sharp and bright, a real glass-cutter. I made one like that for a guy and he really liked it somehow, but it wasn't my cup of tea. But then again, it had an A6 magnet which smoothed that added treble out a bit.

Neck pu's benefit from a stronger screw coil, and the good news is they're not quite as fussy about the ratio.

I don't know if mismatched coils would be effective on a bass pickup because you're dealing with a much longer scale which would probably diminish the effect somewhat. Plus you're obviously dealing with totally different freq's and different desired tones so the right coil turn ratio would probably very different too.

But you're the resident bass pu expert so only you could tell us via your own experiments if mismatched coils would be a viable bass pu design.

[David Schwab]

My main concern has been noise. I want really quiet pickups. My coils are totally symmetrical, since there are no adjustable poles. I always have a very small mismatch, but that's due to having to manually stop winding at a number!

It's something I'll probably experiment with at some point. I know Bartolini does it also.

[Zhangliqun]

For what it's worth, I have not noticed any noise with my mismatched buckers, or at least no more than a symmetrical humbucker, and I've taken them to many gigs. Something roughly 90% to 95% humbucking should still be really, really quiet. Maybe a minor concern at a session but totally negligible live.

I say give it a try, the sound might be bad or indifferent -- or it may be so great that the slight increase in noise will be a small price to pay. You could tell your customers up front this very thing, not 100% humbucking but more than close enough, and the sound is way more than worth it.

[Possum]

noise

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....

[Joe Gwinn]

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....

The reason it works is that the match doesn't need to be perfect to be effective. The hum frequency has little to do with it.

Let's work this out:

Consider a humbucker containing two identical coils, each nominally 5 Kohms DC resistance, of near-equal turns count. Because the magnets in one coil are reversed compared to the magnets in the other coil, the music voltages add while the hum voltages cancel.

Let us call the music voltage from coils one and two M1 and M2 respectively. Likewise, the hum voltages will be H1 and H2 respectively.

The ratio of their turns counts will be r12, which will have a value near unity (because the coils are almost matched). This is also the ratio of the DC resistances, assuming that the same kind of wire is used to wind both coils.

The total music voltage will be Mt=M1+M2= M1+r12*M1=M1(r12+1), or about 2*M1.

The total hum voltage will be Ht=H1-H2=H1-r12*H1, or (r12-1)*H1.

Now, without the humbucking arrangement, the hum voltage would have been H1+r12*H1, or about 2*H1, following the same pattern as the music voltage, so the remaining hum voltage fraction is ((r12-1)*H1)/((r12+1)*H1).

The H1's cancel, leaving (r12-1)/(r12+1). This is the ratio of the hum voltage with humbucking to the hum voltage from a single coil having the same number of turns as the sum of the two coils. This formula holds whatever the actual strength of the hum field - that's the meaning of H1 cancelling.

So, if we assume two coils, one 5 Kohms, the other 5+1.5= 6.5 Kohms, r12=6.5/5= 1.3:1, and the hum is reduced to (1.3-1)/(1.3+1)= 0.13, or 13% of what an equivalent singlecoil would have generated.

As far as audibility is concerned, this is a 20*Log10[0.1305]= 17.7= 18 decibel reduction in hum, which is quite substantial.

[NightWinder]

shit wire

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....

Thats funny. I have wound as much as 1,000 turns and not noticed any audiable hum whatsoever (using 43 and Unwaxed). BTW, the 42 from mws is bunk......It really seems shaddy. I may try Electrisola. DO they sell pe. This batch from mws is different from what I had gotten 6 months prior, from them.

[Mystic]

Well. I seem to be having another fitshit. The Offset is been used in the past, but i have switched from A2 to A4. The A4 seems to want, and need a higher offset to tighten the lowend? This is QUack!! I am reaching about 600 turns differing.Nearly .80 off. The prototype was at .50ohm off, and the lowend just seemed to need tightening.......this is daunting.......

Have you tried the offset on the other coil?

[Possum]

MWS

All MWS PE is REA Magnet Wire manufactured. They are the only ones making PE in the US. Here's the Elektrisola enamel wires page, I don't think any of this is what we call plain enamel, maybe Joe knows the technical terms, all the polsysol ones aren't.

MWS doesn't cherry pick spools so you get what they send, so O.D. sizes can and will vary somewhat. If anyone knows another source for PE I'd sure be interested but Greg contacted a wire company for me and they say all they can get is East Coast manufactured and that means REA or Elecktrisola. I don't know the technical name of plain enamel that we use, plain enamel is a guitar pickup maker's term :-)

[Joe Gwinn]

All MWS PE is REA Magnet Wire manufactured. They are the only ones making PE in the US. Here's the Elektrisola enamel wires page, I don't think any of this is what we call plain enamel, maybe Joe knows the technical terms, all the polsysol ones aren't.

Wher's the URL?

The term "plain enamel" always covered a wide variety of compositions; each magnet-wire maker had his own varnish recipe and coating & curing process.

Yes, varnish. Plain enamel was developed from varnish, the same stuff one uses on wood. The best varnish is spar varnish, used on exposed wood parts of boats.

If anyone knows another source for PE I'd sure be interested but Greg contacted a wire company for me and they say all they can get is East Coast manufactured and that means REA or Elecktrisola. I don't know the technical name of plain enamel that we use, plain enamel is a guitar pickup maker's term :-)

I don't know that anybody still uses the "plain enamel" coatings of the 1950s and 1960s, and there are much better coatings available today. So, what is it about plain enamel we are trying to match?

MWS doesn't cherry pick spools so you get what they send, so O.D. sizes can and will vary somewhat.

True of all wire makers. The wire on a given spool will be quite uniform, with most of the variation being from spool to spool. So, buy big spools.

[Spence]

[QUOTE=Joe Gwinn;12601]

I don't know that anybody still uses the "plain enamel" coatings of the 1950s and 1960s, and there are much better coatings available today. So, what is it about plain enamel we are trying to match?


Much better coatings eh? That's the type of answer I get from my main wire supplier when I ask for Formvar coated wire.

Yes, why would anyone want that old rubbish or the NOS PE coated wire I still use?

Because that's what was used.

[Steve Conner]

I'm not a pickup maker, but I am an electrical engineer. I once wound a transformer with "NOS" enamelled wire and got a very nasty surprise, as the enamel had flaked off and shorted it out. The whole thing went up in smoke within a few seconds. I can't imagine how much worse this problem would be with the hair-thin wire that is used in pickups.

To my engineering brain, the only things that matter about magnet wire coatings are the thickness and the dielectric constant. (This latter affects the self-capacitance of the coil, hence the frequency of the resonant peak.) Any magnet wire maker should be able to specify both, so it should be easy enough to find a modern wire that behaves the same as whatever NOS stuff you like.

Of course, IMO, YMMV, but if someone offered me pickups handwound with NOS wire I would run a mile for the above reasons. Unless shorted turns actually sound good or something.

[Spence]

You're experience of NOS wire isn't everyone's. Yes sometimes a batch of wire will have a very bad enamel that comes off in a kind of dust. I wouldn't use that. That would be absurd. Specialist manufacturers have no problem copying enamel coatings either so it's possible to buy new.
There are plenty of PAFs out there that have never failed..wound with plain enamel.

The key thing that maybe I should have explained is that I specialise in making pickups that are true to the original. It's the detail that customers pay for. Who would have a problem with that?

Oh and I'm an instrumentation engineer so yeah I have a rough idea of what I'm talking about. Wouldn't want to bragg about it though.

[Possum]

what is dielectric properties and how.....

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