Giant Bass Pickup for Ridiculous Single String Bass

[Big_Bur]

Hello!

I'm new here and new to guitar building. I love woodworking and have been playing bass for about a year and really wanted a fun project to combine the two. I came up with the idea of building a single string bass using the heaviest string I can find (.270 gauge) and tuning it to a ridiculously low note. it's not the most useful instrument in the would but seems fun.

originally I was just going to buy a J-Bass pickup and turn it sideways but that seemed boring. I decided what I want to do is build a single, 2 inch in diameter pickup. on the finished bass it'll look like a two inch metal disc under the string.

I'd like to get some opinions on this and some advice on how to go about it.

I was thinking about tearing apart a speaker magnet. They're built with a magnet around a metal core which is attached to a large metal disc. I was thinking I could remove the round magnet, coil the wire around the core and attach a neodymium magnet to the bottom of it. it seems like it should work but I don't know what gauge magnet wire I should use or how strong of a magnet. I also don't know if the core of a speaker magnet is an appropriate metal to make a pickup out of.

Any help, thoughts or opinions would be great!

[Bizman62]

There's two ways to build a pickup and your explanation is mixing them. Either your polepiece is a magnet or the polepiece is steel to which you attach a magnet. Two magnets may cause anomalies.

That said, you can use any magnet you have at hand as well as any bolt or a piece of steel rod. Or you can simply buy a cylindrical magnet for your pole piece. Note that a cylindrical neodymium magnet of some 20x20 mm is VERY strong! About 15 kg pull compared to the 4 kg of an Alnico! Check for variations e.g. here: https://www.first4magnets.com/

Since we're talking about a highly experimental thing here, there's no rules for the wire gauge. A pickup is a combination of the strength of the magnet and the number of windings. Knowing that neodymium is stronger than ferrite magnets, well... All I can recommend is to build several of them, or build one with a swappable pole piece and detachable magnets for experimenting.

[Big_Bur]

7 hours ago, Bizman62 said:

There's two ways to build a pickup and your explanation is mixing them. Either your polepiece is a magnet or the polepiece is steel to which you attach a magnet. Two magnets may cause anomalies.

That said, you can use any magnet you have at hand as well as any bolt or a piece of steel rod. Or you can simply buy a cylindrical magnet for your pole piece. Note that a cylindrical neodymium magnet of some 20x20 mm is VERY strong! About 15 kg pull compared to the 4 kg of an Alnico! Check for variations e.g. here: https://www.first4magnets.com/

Since we're talking about a highly experimental thing here, there's no rules for the wire gauge. A pickup is a combination of the strength of the magnet and the number of windings. Knowing that neodymium is stronger than ferrite magnets, well... All I can recommend is to build several of them, or build one with a swappable pole piece and detachable magnets for experimenting.

thanks for the input. i'm confused though. how was i mixing the two ways. if i remove the magnet from the core, coil the wire around the core and then attache a magnet to the bottom of the core, isn't that exactly what you said to do? or am i confused about something?

[Bizman62]

Oh, I may have misread your post. I thought you were going to use both the round magnet of the speaker and a neodymium one together.

Anyhow, the core has to be magnetic, either by being a magnet or being some ferromagnetic material like iron with a magnet sticked to the bottom.