what size resistor to drop 18v to 9?

[BowerR64]

I have some older active live wire pickups and i think the single coil sounds better on 9 volt and the double sounds better with 18. Can i split the 2 using a resistor to drop the voltage a little to the single.

The double sounds really nice at 18 on the dirty channel but the single sounds a little to hot and gets muddy. It sounds better at 9 when i flip to the clean channel. I want the hard over drive with the bucker but a nice clean output on the single. I think at one time i had some resistors inline with the single or somthing its been so long i cant really remember.

[BowerR64]

Re: what size resistor to drop 18v to 9?

how can i calculate what resistors i need to bring the voltage down?

[ArtieToo]

Re: what size resistor to drop 18v to 9?

You can't really drop the voltage using a resistor in this type of application. Just remove one battery, and bypass its connector. You could use a Radio Shack battery connector, plugged on to the jack, with its wires shorted together if you didn't want to make the mod permanent.

btw - The reason you can't, or shouldn't, use a resistor as a voltage regulator, is its value is based upon current draw. So, the value you'ld pick would only work while the pup was at a static load condition. If the current draw changed with output signal, (likely), the voltage drop would also change. If you switched on a second pup, the voltage would change again. (Probably drop to half.)

[zonniewiw]

Re: what size resistor to drop 18v to 9?

Hoi ,

I have a handmade guitar with live wire set ssh , and the guitarbuilder who made it installed a mini switch where you can select some kinda "active - non active tone" for the two sigle coils , the humbucker stays always full shred , in the "non active position" the single coils have a warm sound , in the "active position" it is just like you put a compression on , I play my clean rithem "non active" and the clean solo´s active

I am not an electric wizzard so I don´t know what he exactly put between , but it looks like a like a resistor , it´s brown and has a lot of coloured rings on it ??

I am at my job right know but if you want I can post a pic of my guitar inside in this tread , over a hour or 6 when I am home


Johnny

if anyone figures it out , I also wanna know

[zonniewiw]

Re: what size resistor to drop 18v to 9?

the picture is pretty bad

but I have a ;

6 pole mini switch

2 resistors

the colours of the resistors are

on one side gold
on the other side black and red


Johnny

[BowerR64]

Re: what size resistor to drop 18v to 9?

looking at the live wire schematic i notice they use 100k pots, im using the stock 250k that are in my guitar that came with the EMG select pickups. Should i use the 100k? i thought i remember in the directions with my live wires it said i could use the stock 250k pots with no problems. Maybe this is why they dont sound quite right?

[ArtieToo]

Re: what size resistor to drop 18v to 9?

Looking at that pic, the colors look like they're either:

red, black, brown, gold - 200 ohm 5%
red, black, gold, gold - 2 ohm 5%

Its probably the 200 ohm. Also, it appears as though he has those on the pups "hot" wire - not on the power wire. Which means, he's just using it to pad the output. Its like an attenuator, to make the pup not-so-hot.

BowerR64: Are you sure those aren't 25k, rather than 250k? All the EMG diagrams that I looked at called for 25k pots.

You could do something like this:



But even that, is not without its problems. Lets say you run the single battery for quite some time, and drain it down to half. Now, when you switch back to 18-volt mode, the strong battery will try to recharge the weaker battery. This is very bad for alkalines, and its why alkaline manufacturers warn you to only change flashlight batteries in sets.

[BowerR64]

Re: what size resistor to drop 18v to 9?

No i have a steinberger spirit guitar, these come with passive "select" made by EMG pickups. These are the bottom of the line cheese passive pickups. Im pretty sure they are 250k, most passive pickups use 250k it does have 2 singles and a double. Im replacing the stock pickups with a really really old set of live wires. One is a single one is a double, one has a red band on the cable and one has a yellow band on the pickup wire.

I may just run 3 batteries, i didnt want to do it this way but it sounds the best. I got room in the cavity for 3 so its not a problem.

If i run both at 18V and i use a resistor on the output will that do the same as running 1 9v on the single coil?

[ArtieToo]

Re: what size resistor to drop 18v to 9?

This is probably one of those things where you'll just have to try it and see. I've never messed with actives at all, and am just speaking from theory.

But here's how the resistor thing works, so you can make an informed decision:

The amount of voltage that a resistor drops, is a function of the amount of current flowing through it. So, lets say that a LiveWire pulls 4 ma:

Using: volts = amps x resistance, then resistance = volts / amps

18 / .004 = 4500 ohms

So, an approximately 4500 ohm resistor will give you 9 volts.
(You're dividing the voltage in half.)
Here's the problem: In all likelyhood, the current draw of the LiveWire will be different while sitting quietly, compared to striking a power chord. As the pup tries to draw more current, the resistor will actually drop more voltage across it. It will be like a little compressor in the line. The more power the LiveWire wants, the less it gets.

It could be an interesting affect . . . or it could fall flat on its face . . . or it could be unaffected. You'll have to tell us.

Sorry, thats all I know.

Artie