What's in an ohm?

[nicholaspaul]

When choosing pickups with similar output, how close is close? I'm replacing pickups in a strat and wonder how close the impedance has to be to not notice a volume drop when switching between pickups. Should they be exact? Is 0.10k close? I know it depends on other things like wire width and windings but I was just trying to compare stats.

[ehdwuld]

ohm is a unit of measure for resistance
wiki will explain
the loudness of the pickups depends on location and height

my JB/ Jazz set are wildly different in resistance
the JB is 16K ohm
the Jazz is 7.3K ohm

the Jazz is in the neck position and the JB is in the bridge

the JB has a certain height at which it sounds good

I set it first then raised/lowered the Jazz till the volume matched

you can further adjust individual strings ( if yours has a tight radius )
by running the pole prices out to follow the curve
I havent had any call to do this as my guitars have the flat fretboards

does this help?

[Funkfingers]

Choosing pickups by numbers is not a good idea - especially since the D. C. resistance is only ONE of the numbers in the equation.

Manufacturing tolerances mean that, even with the best will in the world, not every example of a mass produced pickup will exactly match the others in the same run.

Now that I have finally tried them, my stock answer to all Stratocaster pickup choice questions is two SD Ant II Surfers and the slightly hotter bridge/treble pickup of your choice.

[Mr.Morton]

i agree with the above posts, dont worry to much about resistance , just worry about tone . neck pickups are made with less wind because the string vibrates easier the further from the bridge .

[idsnowdog]

When choosing pickups with similar output, how close is close? I'm replacing pickups in a strat and wonder how close the impedance has to be to not notice a volume drop when switching between pickups. Should they be exact? Is 0.10k close? I know it depends on other things like wire width and windings but I was just trying to compare stats.

The standard of precision is +/- 10%. If a pickup is 10K that means there could be 1K of difference between pickups. The measuring equipment itself may only have 10% precision.

Also the resistance measurement varies with ambient temperature. I have measured pickups at room temperature and below freezing and the variation has been nearly 2K. I wouldn't worry about small variations in resistance.

[Funkfingers]

Ohm is where the heart lies.

[nicholaspaul]

But if the heart lies, where is ohm? [marillion!]

Thanks Ehd, Funkfingers, Mr M and idsnowdog. That all helps. I did realise that it's just specs on a spec sheet, but buying pickups 'sight unseen' makes it tricky. I was just trying to consider the impedance for what it is and not as an empirical rule. I won't even ask about string gauge, pick thickness, cable length or amp type! WAY too many variables!!

What makes this more frustrating is that manufacturers always state impedance in a way that makes it easy to think lower impedance equals vintage tone, and higher impedance means hot.
And I'll try to make sure I'm always playing above zero

I think I need at least one guitar I can play around with and swap pickups in to experiment.

[idsnowdog]

A low DC resistance does not necessarily imply vintage tone. A pickup could have low DC resistance but still have a modern voicing. However their output level in millivolts will probably be similar.

In general when DC resistance increase a pickup becomes darker, more compressed and output increases. Unfortunately a lot of "vintage" style pickups fall apart with high volume and distortion levels. However higher output pickups may not have the same sensitivity or respond the same as vintage style pickups.

[Condemned soul]

Sorry I didnt see this earlier. Here is some background information.
Direct Current [DC] voltage
Think about a garden hose hooked up to the water pipe.
Open the valve and water comes out, the amount is dependent upon the valve position. This is the function of ohms in a dc circuit. The controlling the amount of water flow.


Alternating current [AC]
Electrical impedance, or simply impedance, describes a measure of opposition to alternating current.
Opposition to frequency response will vary with several factors in the circuit.


High tech method to analyze guitar pickups:
http://www.syscompdesign.com/AppNote...ar-pickups.pdf


The old U.S. Navy electrician’s manual which dates back before my birth. Yes , this book is old. I also realize that some members are strongly anti-military. But this manual has some useful information.

There are chapters covering basic circuits, magnetism and vacuum tubes. It still has some useful information.

http://www.rfcafe.com/references/ele...E_OF_CONTENTS_

Vacuum tube theory

http://www.rfcafe.com/references/ele...apter%2019.htm

[nicholaspaul]

Good to know, idsnowdog. Thanks.

Um, Condemned, thanks for the links. My head hurts now. That's great stuff to share though.

I guess the allowance you have for a pickups that vary in power is the height adjustment for each pickup.

Apart from the experience of others, and while reading manufacturers material, what do you go by? The oddly vague and subjective description of tone and EQ? A combination of everything? Luck?

[Hurricane]

An - H -

[crusty philtrum]

Furniture and carpet ?