Super Low Resistance and Fat Coils.

[murraysp]

I am making a guitar for a school project. I have made one previously but this is the first time making pickups. Due to my ignorance and status as a novice i am using extremely thick wire. It is 28 BG (british guage). I am in Australia, sorry dont know the conversion. Anyway it is a very fat coil. So i measured the resistance after looking at some standards, i got 6.1 ohms. i know ohms. there are no zeros after that! so i made a kind of jack white testing jig with one string and it made a noise. that surprised me. the only problem is it requires about half of my amp output. that would be really loud with my normal guitar. i have read many of the threads about low z pickups and how they use a preamp. i have seen a kit on ebay to purchase which i will put in the guitar. i was hoping someone might have some advice regarding preamp schematics (i would like to make it) or any other way to boost the output of the pickups. if that fails i will purchase some stewmac kits and go from there. i just dont know how long it would take to get to australia or how much it would cost.

Regards,

Murraysp.

[888guitars]

Are you using any magnets? are they charged?

[David Schwab]

You need a step up transformer or preamp.

See this thread:

http://music-electronics-forum.com/t5447/

[murraysp]

yes i am using some very strong neo magnets which i have stacked and glued into pole pieces. they are are really strong. i tryed making a preamp but i do not think my input was enough. you say that a transformer would work? if i figured out the required input of the transformer would that be sufficient. i have more knowledge in that field than in preamp. so far i have bought one which wasn't for guitars and it didn't work and i made the discrete JFET preamp and it made very little difference.

THanks.

[Mike Sulzer]

If they are very strong, they are going to cause "stratitis", that is, excessive pulling on the string that can cause harshness and warbling, especially when you play around the 12th fret on the #6 string, in my experience.

Alnico magnets are strong enough to be "too strong". Neo is much stronger and can be can be applied in interesting ways. I use 1/32" thick neo disks on top of high permeability pole pieces.

yes i am using some very strong neo magnets which i have stacked and glued into pole pieces. they are are really strong. i tryed making a preamp but i do not think my input was enough. you say that a transformer would work? if i figured out the required input of the transformer would that be sufficient. i have more knowledge in that field than in preamp. so far i have bought one which wasn't for guitars and it didn't work and i made the discrete JFET preamp and it made very little difference.

THanks.

[murraysp]

i am aware of this phenomenon but i do not think it will be an issue. do you have any tips on raising the output. i have heard of a boost pedal also being used. with a preamp is there anyway to determine the minimum input as this appears to be my problem.

[Mike Sulzer]

i am aware of this phenomenon but i do not think it will be an issue.

Why not? You use strong magnets, you get stratitis.

Did you make your stack go all the way through the coil? Why? The magnetization is very much frozen into neo. That is, when you stack two neo disks, they each contribute to the magnetic field as they would if used alone, and the total field is just the sum of the two. Since the field falls off with the cube of the distance (for disrtances approximately greater than the diameter of the disk), making the stack long adds little. There is a good reason for making the core extend all the way through. When you use a high permeability material, it helps guide the field from the vibrating field through the coil. This is one way to get the output up some.

You need a transformer unless you want to get involved in making a really low noise preamp.

[fieldwrangler]

Neo Topping

Mike Sulzer said:

I use 1/32" thick neo disks on top of high permeability pole pieces.

Mike -

Do you mean on the string side of the pole pieces?

Does this give you a more desirable sensing field than putting them on the bottom?

Bob Palmieri

[Mike Sulzer]

Do you mean on the string side of the pole pieces?

Does this give you a more desirable sensing field than putting them on the bottom?

Bob Palmieri

Yes, on the string side. Neos are permanent even in very small flat pieces, and very strong. The high permeability pole piece increases the strength somewhat.

The purpose of the permanent magnet in a pickup is to magnetize the string so that when it vibrates, it makes a fluctuating field through the coil. This is a simple, inexpensive, and very effective way of doing it. You can choose the field strength with the size of the magnet. I do not think that there is anything special about the shape of the field.

[murraysp]

on a more general note, those magnets are amazing. it is next to impossible to pull them apart.

i shall keep you posted as to my super duper fat coils.