New Builder, Crazy Mono String Bass! OPINIONS?!

[Big_bur]

I'm new to guitar building and for some reason I've set my mind on a wacky little project. It won't be the most useful instrument but I want it to be as interesting and unique as possible.

I want to build a single string, mega bass. I want to build it from scratch as much as I can. My plan so far is to use a .270 gauge string tuned as low as it'll go. Because there's only one string I want to make a custom pickup out of a speaker magnate to make a giant, two inch round, single pickup. On the finished build it'll be a polished metal disc under the string.

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 get rid of the round magnet, coil the wire around the core and attach a neodymium magnet to the bottom of it. It'll run direct to the jack. 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.

For the body I want to do something a bit narrow with two contours on the bottom similar to a Maverick Dorado so it can be used in a standard sitting position and more upright sitting position. I'm not sure what wood to use. I might try to beautify a piece of good plywood and layer it.

The neck will also be narrow and I'm debating whether to go fretless or not. I'm also not sure if I'll have problems with the tension of such a heavy string and how i'll need to construct the neck to accommodate it.

I'm currently looking for interesting tuning machines. Basically I want anything other than a standard bass tuner sticking off the side. Suggestions would be great here. I would love something inline with the string like a headless tuner but I'm not sure a standard headless tuner would be able to handle such a heavy string. I've been considering building my own but metal working isn't my thing and I would hate to just use a hardware store bolt and wingnut like I've seen some people do.

Basically the idea is, simple as possible but nothing standard, without it looking like a hunk of junk of course. I want it to be a show piece if I can manage it.

Any input would be greatly appreciated.

 

[Beej]

I like to draw things out fullsize when building, if possible. Helps to visualize where things can go and allows me to make accurately sized layouts.

Were I doing this, I'd probably order a string asap so it's in my hands and I can see how it relates to other components. The dimensions will dictate how the nut works, the breakover angle of the nut, the saddle piece, and where it's retained on the bridge. None of those will be stock with a 0.270 string.

If doing the speaker magnet pickup is something important, then that would probably be the first thing to tackle - both to get it working, and also because the size/dimensions will probably dictate a lot of the rest of the instrument. Honestly, because the string and scale length are also unknowns and you may have some prototyping to do, it may be worth getting it into a functioning instrument with a regular pickup, and then tackle the pickup separately.

Not sure what tuning you'll get with that 0.270 string, but it may sound something like: "fup-a-dup-a-dup"

 

[Big_bur]

I like to draw things out fullsize when building, if possible. Helps to visualize where things can go and allows me to make accurately sized layouts.

Were I doing this, I'd probably order a string asap so it's in my hands and I can see how it relates to other components. The dimensions will dictate how the nut works, the breakover angle of the nut, the saddle piece, and where it's retained on the bridge. None of those will be stock with a 0.270 string.

If doing the speaker magnet pickup is something important, then that would probably be the first thing to tackle - both to get it working, and also because the size/dimensions will probably dictate a lot of the rest of the instrument. Honestly, because the string and scale length are also unknowns and you may have some prototyping to do, it may be worth getting it into a functioning instrument with a regular pickup, and then tackle the pickup separately.

Not sure what tuning you'll get with that 0.270 string, but it may sound something like: "fup-a-dup-a-dup"

I'll be working on the pickup first. there are a lot of ways to tackle it and i want to make sure it works before I move on. I want to try at least two different gauge magnet wire and two different winding each along with a few different strength magnets. if possible I want to build four pickups. one thin gauge with a short wind, one thing gauge with a long wind, one thick gauge with a short wind, one thick gauge with a long wind and then try three or four different magnets on each. for testing i'm planning on building a jig to hold the pickup over my four string bass so I can have a direct comparison for how it sounds.

Do you have any idea how important knowing the exact impedance for the coil is? does it matter that much for a build like this?

I'll get my hands on the string before I start building of course. I already have it sourced and it's an expensive little bugger. about $50 for a single string.

i've been trying to research break angles but i'm new to this don't fully understand why different angles matter. could you help fill me in?

 

[wraub]

Potential food for thought, depending on your desires...


Whamola - Wikipedia

whamola - Bing

That One Guy
That 1 Guy | Awooooooooooooooo!

 

[Bruce Johnson]

Check out this thread:

Magnets & Copper Wire: A Pickup Building Thread

That's where those of us who build our own crazy custom pickups share our crazy ideas.

A few quick points about designing a pickup for this one-string monster:

Don't worry so much about the magnet wire gauge or the impedance or the DC resistance of the coil....yet. Those are details that you can mess around with later on, if you really want to get into pickup design. The three critical things are:
1.) You need a magnet, or a structure of magnets and steel bars, which has a powerful magnetic field around it. It has to be mounted so the string passes through a strong part of the field.
2.) The coil needs to be almost completely within the magnetic field of the magnet structure that you choose.
3.) The coil needs to have enough turns to amplify the signal to a level that the amp can work with.

The important thing to understand is that the coil doesn't detect the string. The string passes through the magnetic field, and when the string wiggles, it makes the magnetic field wiggle. The other end of the field passes through the wire of the coil. As the wiggling magnetic field passes through each wire, it creates a tiny electric signal. The way to get the signal big enough to be able to use it, is to wind the coil as thousands of turns of wire. That multiplies the signal level by thousands. As a general rule, you'll need at least 5000 turns of wire, regardless of what wire gauge you use.

Making the pickup real big in diameter doesn't gain you anything. If the turns of the coil are outside of the magnet's field, you won't get much signal at all.

A simple, strong pickup would be a 1/2" dia x 3/4" long magnet, with one end mounted within 1/4" of the string. The coil is wrapped in a simple bobbin right around the magnet, 5000-8000 turns of magnet wire, anywhere from 38 ga to 42 ga.

 

[Beej]

I'll be working on the pickup first. there are a lot of ways to tackle it and i want to make sure it works before I move on. I want to try at least two different gauge magnet wire and two different winding each along with a few different strength magnets. if possible I want to build four pickups. one thin gauge with a short wind, one thing gauge with a long wind, one thick gauge with a short wind, one thick gauge with a long wind and then try three or four different magnets on each. for testing i'm planning on building a jig to hold the pickup over my four string bass so I can have a direct comparison for how it sounds.

Do you have any idea how important knowing the exact impedance for the coil is? does it matter that much for a build like this?

I'll get my hands on the string before I start building of course. I already have it sourced and it's an expensive little bugger. about $50 for a single string.

i've been trying to research break angles but i'm new to this don't fully understand why different angles matter. could you help fill me in?

I think bruce and the pickup thread probably have you more than well covered enough with regard to the pickups. Regarding the break over at the nut, I was really just thinking that due to the inherent stiffness in a string that thick, the nut may need to be taller than usual with a deep slot, but that the shape inside the slot will be important to get right so it sits well. In addition, because the string is stiff, if you just bent it over the nut into a normal break over angle, it would probably arch back over the nut! Having a string in hand will help figure out what shape this needs to be, and what angle is enough to hold it securely in the nut, but not cause too much deflection. I dont think we're into deep science here, just that normal scale and gauge bass-planning may go out the window here with such a heavy gauge and long scale.

 

[rudy4444]

Bruce's reply is excellent information on the basics of what you're going to need to design your instrument.

You might consider spending some time doing searches over at the Pickup Winding Forum.

[Invalid or Expired Link Removed]

It's full of all sorts of information on coil winding and home made winding equipment. It's a popular place for all sorts of folks at the extreme end of magnetic pickup design.