Experimental rail pickup construction: wiring question

[Jim Bonnell]

Thanks David, I don't feel so alone. Great thread Jason.

[Jason Rodgers]

It would have been pretty frickin' amazing if I wound my first humbucker set with no hiccups. It was actually a relief when that start lead snapped and it became clear that a rewind was necessary. Further up the thread here, where I was clearly in denial that I had a short, it was the thought of all the steps necessary to get back to plugging in the guitar to test that was the biggest hurdle. But after the path became clear, it wasn't actually that much work, nor that much trouble, to cut the coil away, clean it up, and rewind.

And Greg and David were BOTH right! Greg said the start and ground were connected, and David said I had a short. The start was shorting to ground.

The rewound coil was potted today between other tasks around the house. I'll have it back under the hood tomorrow.

[Jason Rodgers]

Back in business: wired up and tested. I'll try to get a thread up for this whole build before GAL. If not, after for sure.

[Jason Rodgers]

Well, I sure had fun showing off my guitar and its pickups at the GAL Convention. David King and Veronica Merryfield were even nice enough to let me bring my pickup winder and guitar along for some show-and-tell after their presentation.

Now that I'm back, I've been playing plugged in a bit. Of course, my first impression was, "Omigod, they work!" (well, after I rewound that one coil), but now that I've had a chance to play through each pickup combination, clean and dirty, with different turns of the controls on the amp, I'm thinking they may fall short of my expectations. They look cool, but everything I've been reading and people have been saying points to one conclusion: these are fairly dark, even muddy, pickups.

Why? All that steel in the cores and all those winds colluded to steal a lot of high frequencies. After David and Veronica's session, they had a separate Q&A session and Veronica offered to test my pickups with her fancy meter to find out more about their capacitance. She graphed out the results on a white board to show that my pickups' frequency peak is a bit lower than typical commercial pickups. And the amp's settings can only do so much to make up for what's not there. There's just no sparkle. They always sound like you've rolled off the tone control by about a 1/3 to 1/2 turn.

Now, granted, an amp can make a lot of difference. The only amp I own is a Polytone Minibrute that I bought many years ago for jazz. My guitar teacher had a Polytone, and it's what you buy when you want to play flatwounds through your neck pickup and get that stereotypical "marshmallow" jazz tone, and it worked really well for that purpose when I was doing that type of playing. Now I play mostly rock, and I don't think this little dude packs the snap I'm looking for. I may need to play through a few amps to find that answer, but I think an open-backed 2x12 of some sort would do the trick. I once had a Peavey Stereo Chorus 2x12 that I sold to buy the Polytone! I may go full circle!

[Jason Rodgers]

After having played these pickups on my first guitar for a month now, my ears have really come to know their tone and understand their lack of clarity and "muddiness." No matter how I dial in the amp (and I'm using John Sonksen's Fender Cyber Twin modeling amp with dozens of presets), the separation between strings isn't there and the low strings overpower the higher. Not that I'm totally unhappy with these pickups and want to rip em out, but I can really hear their limitations.

And earlier this week, I got another set of ears to confirm this observation. I brought the guitar to school during the inservice week because my friend who teaches at the other middle school wanted to stop by and try it out. He brought his Fender 2x12 solid state and some effects pedals. After jamming for 15 - 20 minutes through a variety of tones and effects, he stops on a full open A across all 7 strings and says, "This end (chunks the lower 3-4 strings) sounds great... but this (strums the higher 3-4 strings) just isn't there." I gave him the big explanation why, and the long-story-short that the high end just won't have that sparkle. Overall, though, he really had fun playing the guitar, and commented on the adaptability of the multiscale fretboard. Actually, he thought the seventh string was more of a challenge to accommodate that the frets!

Since pickups can be swapped out without too much trouble, I may make a new set for this axe some day. In the end, though, the experience of making this first set was educational and exhilarating!

[Mark Swanson]

I also find the extra string is harder to get used to than the multiscale frets.
I don't recall how close the pickups are to the strings, but backing them away should help your problem some. It might help if the higher strings end up a little closer than the lower ones, too.

[Jason Rodgers]

Yeah, we both said the same thing: the extra string throws off your muscle-memory for your pick reach to middle strings.

Move the pickups farther away from the strings? Right now, with the strings pressed down at the 24th, the rails are just a little more than 1/8" away. When I pull the guitar apart to re-profile the neck and adjust the bridge base, I was going to stick some taller foam under the pickups to try raising them closer to the strings. Angling them to try to balance the low and high strings, though, is an idea I will have to try.

[Mark Swanson]

The closer to the strings they are, the louder, bassier and muddier they get. If you back them away it might help a whole lot. If you can, try rigging a temporary screw-adjustable frame or something and then you can easily experiment with the proper adjustment. When it's as good as it gets, measure and make a permanent setting.

[Jason Rodgers]

The foam is maxed-out at the clearances noted above, so I have the ability to back them off and attempt bass/treble angling. I'll give that a try tomorrow.

I guess I don't understand the tonal changes that come with pole proximity. I thought that bringing pickups closer brought up the volume, but also increased the high frequencies. I've been reading up on the MEF on the pickup pages and read an interesting fine tuning description for humbuckers (with poles and screws): to warm up the tone, drop the pickup and raise the screws; to brighten the tone, lower the screws and raise the pickup. Of course, these are blades, so I don't know how they fit into that description.

[Mark Swanson]

I think it dep3nds on the pickup type, and the many variables of them all. I think of it like each pickup has a peak in its response curve, and bringing it closer will increase the tone at that peak and backing down will flatten it a bit more.....and to me, what you describe your pickups doing could be lessened by backing them off. Only one way to tell!

[Jason Rodgers]

I dropped the bass side of the pickups about twice the distance that they had been initially set, and I think I can hear a difference, but very slight if at all.

Here's another thought: each pickup has six 1/8"-1/8"-1/2" neo magnets under each core, and they're not glued or potted in place. When I pull this thing apart, I'll pull a couple off and see if that makes any difference.

[Dave Weir]

Jason, thank you for this thread and thank everyone for all the comments and advice. It's very interesting.
I'm also am building my first pickup. It is like a mini humbucker but with bar steel on both sides, so no adjusting screws.
It's wound to about 7K and it's not in a guitar yet but I wired it to an amp and tested it with a Jews Harp. Sounds pretty much like an amplified Jews Harp should sound. But it's kind of noisier than I would expect and I'm thinking it's because there is no cover and no back plate.

Also, the two steel bars sit on either side of a bar magnet. They are not as low as the bottom of the magnet, so they would not touch the bottom plate. The bottom plate would only touch the magnet, and typically be soldered to the cover.

It is very quiet when I touch the ground of the jack I have it wired to. It is not too bad if I lay it on the floor and get a few feet away from it. It is most noisy when I put my hand very close to the pickup, but don't touch it. I get a somewhat different but even louder noise when I touch the tip terminal of the jack. It is also not bad when I use a wireless transmitter.

So here are my questions:

Are both the cover and the backing plate important for noise reduction? I would rather not have a metal cover.

Are the two steel bars supposed to be grounded? I checked some other rail type humbuckers. Bill Lawrence rails are grounded. DiMarzio rails seem to be wired together, but not grounded. (This could be something I did Wrong) On one of my P90s, some poles seem to be grounded and some not.

Are magnets conductive? I have a bunch of what I think are ceramic magnets and they don't seem conductive. The magnet in my pickup does not seem conductive. I have others that are chrome plated, so I don't think it proves anything, but they are conductive.

If the bars are supposed to be grounded, and the magnet is not conductive, how do the bars get grounded?

Jason, I apologize if this is hijacking, but you've got such a great audience here I think they can help me, and maybe some answers will help you. Or maybe you've been through this and get me back on track.

[Mark Swanson]

I think I would want everything grounded to the baseplate. Magnets inside fender single-coil pickups are not grounded, but in your pickup I think they should be. And the screws and magnets inside a P-90 should all be grounded because the screws all pass through the baseplate which certainly is.

[Jason Rodgers]

Thanks, Dave. I'm glad my trials have been instructive.

Ground it all. However you need to go about doing it, ground it.

As I'm very new to this, I can't answer your main questions about covers and base plates. I do understand that different metals in covers and base plates (which are grounded) can change the tone of the pickup. And the cover doesn't need to be metal to contain shielding (which is grounded).

When it comes to noise reduction in humbuckers, my understanding is that well-matched coils and copious shielding in pickup and control cavities (you guessed it, grounded) and on leads is the key.

[Mark Swanson]

If your pickup is assembled and wired right, it should be quiet without a cover. There are a ton of humbuckers out there with no covers, and they are quiet. If you have all of your coils wound in the right direction and the magnetic polarity right your pickup should be quiet. Shielding in the body isn't such a big deal in a humbucking guitar, it's really nice but if you have wired everything with shielded wire and your pickups are right you can do without it. And don't forget a string ground.

[Dave Weir]

I'm making another one with a copper back plate.It will be grounded and pressed up against the magnet. But that doesn't ground the blades. Apperently ceramic magnets are not conductive, and Alnico magnets are poor conductors. But switching to A5 or A2 for production pieces is probably a good idea anyway. So I think that will ground the blades.
We'll see if it helps with the noise. I still don't get the big increase as my hand gets near the pickup. I don't think i've heard it like that before

[Jason Rodgers]

Scroll through this thread until you find the part where I was stuck on the grounding of the blades. I used solid core copper wire peened into tiny holes. (If you do this, be careful: while my first coil wind got a little messy and probably resulted in the short that necessitated rewinding, this grounding method is also suspect, as the heat from my poor soldering skills may have traveled back to the core and melted through some insulating layers.)

In another discussion elsewhere, David King suggested something similar: peening a short piece of larger gauge copper wire into a hole in the blades, but then using that as a solder point for your usual gauge ground wire (stranded or bare drain). My next set of pickups will be laminated core blades, and I'll use this method to ground them.

So yes, ground those blades directly, and don't trust the contact and/or conductivity of any other parts to do the job.

I'm learning as I go, and in addition to the help from knowledgeable folks around here like Mark, David, and Greg, visiting the MEF has been very educational. For example, here's an old thread about EMG pickup construction. Go down to post #23 where David Schwab tears one apart to reveal the brass screen shielding they use. http://music-electronics-forum.com/t2145/

[Dave Weir]

The second pickup with the copper backing plate is much less noisy. I don't think my procedure is so precise than I can say with just two examples that this is the solution. It's still noisier than an Artec Mini Humbucker.
The new one is also wound to around 9.2 or so. I don't think hotter could possible mean less noisy.
The blades still aren't grounded in the new one. It seems like from looking at samples and from what has been said, some are and some aren't. It sounds like it is never a bad idea, and probably a good idea. I guess any un-grounded metal is an antenna, and grounded metal is a shield.
Drilling and penning sounds kind of tricky, but seems like it would be a very good connection. I am also thinking using copper foil tape instead of a backplate and use that to ground the blades.
Here's a picture of one of the prototypes. The resin case has 1/4" radius corners, so it makes it easier to rout a very tight pocket.

[Jason Rodgers]

I drilled the holes in the cores before winding, or course, but "preening" sounds a little too forceful of a description: I folded over the end of the copper wire, pressed it into the hole with needle-nose pliers, then gave it a goodly nudge with a nail set or awl to mush it in and make it stick. Then, the ground leads were taped to the cores, under the insulating Kapton tape, and coils wound over them. There will be no risk of them wiggling and breaking off.

[Jason Rodgers]

I'd like to announce my retirement from the super-cheap-scrap-bin-DIY-original guitar pickup business. There was a certain satisfaction in the trip documented herein, but I think I've proven to myself it's possible, and now I'd like to just get on with building. As such, I've placed an order with Mojotone for 3 guitars worth of bobbins and related parts to play around with different cores (blades vs slugs vs screws), magnets (ceramic 8 vs neo 42), and wrap counts to find some interesting sounds. I'm happy to spend $50 on parts if it means I get to wind a coil sooner.

Don't get me wrong, I still have a deep DIY streak, but I'm finding there is a balance that can be sought to satisfy that definition and still make forward progress toward completed instruments that I get to play.

EDIT: I just realized I said "preening" in my previous post, instead of "peening." Stupid spell-check. Don't preen your ground wires.