Why SD and home-made are different?

[David Schwab]

I tried SPN42, SPN43 and PE42 and they were all hand-wound. No shorts. German silver baseplate was used and there was no cover. I also tried a couple of StewMac humbucker pickup kits as well. No matter what I tried, the response has the scoop after 10kHz, while SD and Gibson pickups don't...

But hand wound how? That was my point....

wHY isn't there details about the "turns per layer" mentioned are you hand winding you pups or machine winding them ?

Exactly. You weren't scatter winding, where you?

Also, how do you know there are no shorts? What did you do to determine that?

I've wound StewMac kits, as well as using average humbucker parts, and while I didn't make graphs, they sound comparable to Gibson pickups.

Also I see a metal cover in the photo. Did the Gibson pickups have covers? Are you certain the covers are the same? The material and thickness of the cover can cause changes to your resonant peak.

[David Schwab]

I hand-wind pickups. The turns per layer should not be a factor, I guess, because I also tried different bobbins with different winding spaces but it did not make much difference...

No, it is a factor. It's hard to be exact when hand winding, but your general winding pattern matters. I'm guessing you might be scattering, while the stock pickups are all neatly machine wound.

[Mike Sulzer]

No, it is a factor. It's hard to be exact when hand winding, but your general winding pattern matters. I'm guessing you might be scattering, while the stock pickups are all neatly machine wound.

I have never wound a coil by hand that had a second peak such as the figure shows. I have not measured it on a machine wound coil either. This is why I think it is probably an interaction.

[Joe Gwinn]

I have never wound a coil by hand that had a second peak such as the figure shows. I have not measured it on a machine wound coil either. This is why I think it is probably an interaction.

That's my instinct as well. Or something odd in the setup.

[David Schwab]

I have never wound a coil by hand that had a second peak such as the figure shows. I have not measured it on a machine wound coil either. This is why I think it is probably an interaction.

I agree. I was referring to the roll off on his coils.

[freefrog]

IME, that mid scoop beyond 10khz is not related to hand or machine winding: I've found it in the response of some machine wound PU's (like the Duncan SH13) while some symetrically wound hand made PU's exhibit the same smooth peak on the slugs side than on the screws side...

In my understanding, the mentioned scoop has to do with the physical specs of the coils and magnetic parts.

[copperheadroads]

I hand-wind pickups. The turns per layer should not be a factor, I guess, because I also tried different bobbins with different winding spaces but it did not make much difference...

Do you ever have a lot to learn ! ...... .

[Rick Turner]

Does anyone here ever measure one half of a humbucker with the other coil not even on the unit and then measure the other half? Then assemble the whole thing and remeasure one coil at a time and then the whole assembled unit.

You'd certainly get to see what each coil does on it's own and then closely coupled to the other coil.

You'd also want to make sure that when testing each coil of a fully assembled unit that the other coil was open circuit, not shorted or shorted to ground.

Of course that would only be good if one really wanted to learn something! :-)

[Mike Sulzer]

I would say half yes. I have noted that there are interaction effects, but moved on pretty quickly to other things. I think it deserves some more effort. By the way, leaving the coil open does not remove all interaction at the resonance. The pickup capacitance "completes the circuit".

Does anyone here ever measure one half of a humbucker with the other coil not even on the unit and then measure the other half? Then assemble the whole thing and remeasure one coil at a time and then the whole assembled unit.

You'd certainly get to see what each coil does on it's own and then closely coupled to the other coil.

You'd also want to make sure that when testing each coil of a fully assembled unit that the other coil was open circuit, not shorted or shorted to ground.

Of course that would only be good if one really wanted to learn something! :-)

[Joe Gwinn]

By the way, leaving the coil open does not remove all interaction at the resonance. The pickup capacitance "completes the circuit".

True at high frequencies. The classic way to sort the effects out in a transformer is to make six measurements (connect A and B in series-aiding, in series-opposing, measure B with coil A open, measure A with coil B open, coil A shorted, coil B shorted) followed by some math.

[Mike Sulzer]

True at high frequencies.

Well, sort of. Really only effective near the resonance where the inductive and capacitive reactances cancel, allowing significant current to flow as a result of the induced voltage.

[csjang]

But hand wound how? That was my point....



Exactly. You weren't scatter winding, where you?

Also, how do you know there are no shorts? What did you do to determine that?

I've wound StewMac kits, as well as using average humbucker parts, and while I didn't make graphs, they sound comparable to Gibson pickups.

Also I see a metal cover in the photo. Did the Gibson pickups have covers? Are you certain the covers are the same? The material and thickness of the cover can cause changes to your resonant peak.

Hi David, here goes my answers.

I would say I do scatter wind because I cannot wind coils like machine by any means...

I know there are no shorts based on the resistance I get.

I agree with you that StewMac kits sound comparable to Gibson pickups. I also don't hear noticeable difference between home-wound and commercial ones. I was wondering why the response is different between home-made Stewmac and Gibson or SD.

Sorry for the confusion. The pickup shown in the photo is Gibson BBP. All other pickups don't have covers. I do know the cover can shift the graph (also potting does too).

[csjang]

I used only slugs on the driver coil. I did not tried magnet though.

[Rick Turner]

Get an SD 'bucker and listen to it and measure it; then take off all the wire, rewind it your way, and see how it sounds and measures. Then you'll know if it's in the materials or in your wind technique and wire.

Eliminate variables to learn what's going on. That and learning to diagnose problems are the two hardest things for electric luthiers to do.

[csjang]

Thanks for the clarification, Mike.