Odd problem with pickup

[Chris Turner]

Hello all,


I've just finished making a Wal-inspired pickup. In this case, the coils are configured like a modern Wal... each pair of coils under each string are wired in series, and all pairs are then wired in parallel.

Here's the problem: with one of the pairs of coils, the DCR reading is bit higher for each coil, at ~2.5 Ohms, compared to ~1.5 Ohms for the each coil in the other pairs. Whether this is due to wire stretching while winding, or the solder connections for the coils in this pair not being as good, I don't know. However, the output from this pair of coils is *far* less than the other 3 pairs. The magnets in these coils seem to be as strong as the others, too.

Any ideas as what is causing this?

Is it simply because the resistance/impedance is higher in this pair, and since the pairs are wired in parallel, less current can flow through (or be generated from) this pair?

[big_teee]

Solder joint maybe?
Do you tape the coils?
I wound a bunch of them a couple years ago, most were around the 2.5k ohms, with 10k turns, best I remember.
Your Circuit boards look great.
Got any pics with them in the bass?
T

[Chris Turner]

Well, it was cold solder joints. Duh!

I could take a pic of it mounted in the bass, but it's not pretty. lol I've just got it sorta taped into a MM pickup shell that I had laying around. These few pickups I'm making are going to be used in some custom basses, so the luthier is going to be making wood covers for them. But yeah, the next order of business is to find some way to make some covers of my own. I've been looking into 3D printing for that, as I think the technology has come far enough along to get some good quality parts. Might have to look into having them vacuum formed, but don't know of any good sources, and I don't have the equipment to do it myself.

Anyways, here's a quick and dirty sample of how it sounds at the MM Stingray position (obligatory disclaimer... I don't have great recording equipment, so it may sound kinda lo-fi): audio sample

[Lollar Jason]

This is why its really important to have an inductance meter and check every coil you make- sometimes the resistance will be as you expect but the henries will be way too low. Its almost always a bad solder joint. Doesnt happen often if your soldering is pretty good or better but it does happen. You can also tell if you accidentally used the wrong alnico grade or if the magnet isnt charged right or if the overall TPL is varing more than you expect, assuming you keep track of your specs. Resistance will vary but henries stay alot closer

[David King]

Chris,
That's a nice sounding pickup and really clean playing too. Reminds me a bit of the Erno Zwaan pickups maybe. I'm not hearing all the low bass I might have expected from a Wal.

[Chris Turner]

Chris,
That's a nice sounding pickup and really clean playing too. Reminds me a bit of the Erno Zwaan pickups maybe. I'm not hearing all the low bass I might have expected from a Wal.

Thanks, David!

I was kind of expecting a bit more lows, too, actually. Each coil is 10k winds of 42AWG around a 1/4" alnico 5 rod. The way I have the pickup mounted in this bass might be contributing to that a bit, though... the screws I have aren't quite long enough to get the poles as close to the strings as I'd like them to be. Then again, Wals have ceramic mags, a steel keeper bar, and steel pole screws, so I imagine a difference comes from that too.

It does really bark when I dig in, though, which I'm liking a lot.

[Chris Turner]

Got the pickup sitting closer to the strings now...

A couple samples for the hell of it:
Fingerstyle
Slap

This thing is pretty broad-spectrum. I dig it, but I think I may try wiring this so that each row of 4 coils is in series, and then the 2 rows in parallel with each other. I'm thinking that'll thicken it up a bit and coax some more mids and low-mids out of it.



BTW, does anyone else use the LightSnake USB for recording? I can never seem to get the levels right... it's either overloading and causing peaks, or too quiet, it seems.

[David Schwab]

Then again, Wals have ceramic mags, a steel keeper bar, and steel pole screws, so I imagine a difference comes from that too.

Yeah, Wals have a lot of steel involved.

[David Schwab]

This thing is pretty broad-spectrum. I dig it, but I think I may try wiring this so that each row of 4 coils is in series, and then the 2 rows in parallel with each other. I'm thinking that'll thicken it up a bit and coax some more mids and low-mids out of it.

The Wals with the passive setup have a very thick tone. I had one here to do some work on. Even in parallel it's a thick tone. That's the same model of Wal you hear on Love is the Drug by Roxy Music.

BTW, does anyone else use the LightSnake USB for recording? I can never seem to get the levels right... it's either overloading and causing peaks, or too quiet, it seems.

Currently I use a Behringer UMC22. It's fairly cheap and sounds great.