Okay ... I need a different source

[SkinnyWire]

Well, it happened again. I've been building a lot of 4-conductor pickups lately, which turns out to be a good thing. I started a thread a couple of weeks back regarding some odd resistance readings from a few pickups. I thought I'd isolated it to the single conductor hookup, but wasn't completely sure. Well, tonight I was working final assembly on several pickup and 1 out of 4 with the latest batch of single conductor from StewMac exhibited the same "odd" behavior.

This was an 8.0k pickup - nearly spot on that value. I connected my DVM to the hookup and it read 7.84k and slowly drifted up to about 7.89-7.9k. I disconnected the center conductor from the pickup and measured the two coils together - 8.03k. Replaced the hookup and got 8.03k. This is I think the 5th time out of the last 10 or 12 pickups using this hookup. It's the first time I've noticed this in the several years I've been using the wire from StewMac, and I ALWAYS take numerous measurements on every pickup during the build process. I'm convinced there's something going on with this hookup wire, though I don't really know what the impact on tone would be (I figure tone suckage since it appears to be capacitive in nature).

If anyone has an alternative source for single conductor braided shield hookup, I'd really appreciate the info. I've looked at Mojo, but wonder if they don't get it from the same source as StewMac. Angela seems WAY overpriced?

Also, what's the best way to test the capacitance per foot? I made a sort of attempt with my LCR meter before assembling these pickups and one of the wires did seem a bit higher than the rest.

[Zhangliqun]

This is normal -- say again, normal -- behavior for any pickup, and it's why most winders prefer to use turn counts over DCR as a way of getting consistent results. Even slight temperature changes will cause fluctuations of DCR readings as you describe. Just handling the pickup will cause the temperature of the coil to rise slightly and the DCR reading to go up 0.1k or more in just a few seconds just from the heat in your fingertips, especially if the room is cool relative to your body temp. It will also read a bit higher after soldering the pickup leads/etc together because of the heat from the solder iron. Metal conducts heat from one end of a metal object to another very quickly, so imagine the effect of soldering leads.

I do use DCR as a guage, but I've learned how to interpret readings for consistent results taking all the above into account. My "official" reading for the customer is the one that's taken after the pickup has sat at room temperature (+/-72F) for a few hours.

In short, no need to panic and buy different wire that will give the same results.

Well, it happened again. I've been building a lot of 4-conductor pickups lately, which turns out to be a good thing. I started a thread a couple of weeks back regarding some odd resistance readings from a few pickups. I thought I'd isolated it to the single conductor hookup, but wasn't completely sure. Well, tonight I was working final assembly on several pickup and 1 out of 4 with the latest batch of single conductor from StewMac exhibited the same "odd" behavior.

This was an 8.0k pickup - nearly spot on that value. I connected my DVM to the hookup and it read 7.84k and slowly drifted up to about 7.89-7.9k. I disconnected the center conductor from the pickup and measured the two coils together - 8.03k. Replaced the hookup and got 8.03k. This is I think the 5th time out of the last 10 or 12 pickups using this hookup. It's the first time I've noticed this in the several years I've been using the wire from StewMac, and I ALWAYS take numerous measurements on every pickup during the build process. I'm convinced there's something going on with this hookup wire, though I don't really know what the impact on tone would be (I figure tone suckage since it appears to be capacitive in nature).

If anyone has an alternative source for single conductor braided shield hookup, I'd really appreciate the info. I've looked at Mojo, but wonder if they don't get it from the same source as StewMac. Angela seems WAY overpriced?

Also, what's the best way to test the capacitance per foot? I made a sort of attempt with my LCR meter before assembling these pickups and one of the wires did seem a bit higher than the rest.

[kevinT]

+ 1. I experience the same fluctuations. As Zhang stated, let it chill for a few hours and then take a reading. I'm also wondering whether my desk lamp, with its 75 watt bulb, heats up the pickup as the light beams down on it as i work.

Also, I believe it was you (skinnywire) a while back when there was a thread about getting a higher resistance from the outer layers of wire of the spool because it was stretched when the wire was placed on the spool.

I've notice that i have to bump up my turn count to maintain the same DCR sometimes, as I move towards the inner layers of wire closer to the center of the spool. It eventully evens out at some point.

[Possum]

....

Its important to have your room at a stable temperature, we're lucky we live in a newer house and its always 70 degrees in the room. But yes desk lamps move the DCR up for sure. I'm relying on turn counts more and more and AC resistance which is slightly less temperature dependent, but nothing is totally stable ever. Even turn counts if you wind too tight your DCR goes up from stretching wire....

[DrStrangelove]

From a couple months back, here are exact numbers on the effect of temperature on pickup resistance:
http://music-electronics-forum.com/s...7&postcount=16

-drh

[kevinT]

wow, i didn't know cooler temps could actually bring down the dcr. Hmmm, i'll have to get a thermometer for my basement where i work. I know it gets cooler than 68 degrees down there at times.

[SkinnyWire]

This is normal -- say again, normal -- behavior for any pickup, and it's why most winders prefer to use turn counts over DCR as a way of getting consistent results. Even slight temperature changes will cause fluctuations of DCR readings as you describe. Just handling the pickup will cause the temperature of the coil to rise slightly and the DCR reading to go up 0.1k or more in just a few seconds just from the heat in your fingertips, especially if the room is cool relative to your body temp. It will also read a bit higher after soldering the pickup leads/etc together because of the heat from the solder iron. Metal conducts heat from one end of a metal object to another very quickly, so imagine the effect of soldering leads.

I do use DCR as a guage, but I've learned how to interpret readings for consistent results taking all the above into account. My "official" reading for the customer is the one that's taken after the pickup has sat at room temperature (+/-72F) for a few hours.

In short, no need to panic and buy different wire that will give the same results.

I don't think you heard what I said. Three out of four pickups were fine in this go round, one read bad. I had a similar thing happen a couple of weeks ago, and that was the first time ever.

I'm fully aware of the effects of temperature and these readings were at stable temp having acclimated in my shop for over 48 hours and being measured without handling them. I've been doing this for years, and this has only surfaced recenty.

I wind to turns because I believe it's the best way to get repeatable results. I test resistances and inductances and capacitance because it gives a measure/indication of how I'm doing and if there might be shorts in the coils, etc. In doing so, once in a blue moon it identifies a problem developed in the 11th hour of assembly so it's more than worth it.

This is NOT normal behavior. Not by any means.

To repeat, I measured 4 pickups one after the other ... pickups that had been sitting untouched in my shop for over 48 hours (i.e., acclimated), but which had not been measured since attaching the hookup ... because they needed time to acclimate! Three of the 4 measured according to previous specs ... rock solid with no drifting ... as they always do/should. One read nearly 200 ohms light and "crept up" over a period of a couple of minutes to a point still under what it reads AFTER I replacing the hookup. Post hookup swap, it was stable AT the expected value with NO "creeping". This is normal behavior.

If it was heating due to current from the DVM I'd have seen it years ago. I've been using the same setup for a good 5 years now. I live in Florida, so my A/C runs pretty much year around. It was over 80 outside yesterday, so the inside was the normal 74 degrees that it always is. I suspect something with the hookup, because at least three times now replacing it with older hookup from a different "batch" fixed the problem. Two others I rebuilt completely so I have two "bad" examples in my shop.

I can live with a few bad wires here/there for now, but an alternate source might be nice.

[Zhangliqun]

I did understand what you said. The mystery to me is that you've never run into this before when everyone else has. I don't think that changing sources of hook-up wire is going to make any difference.

It could also be that your meter is a little screwy. Mine gets that way sometimes, I turn it off and turn it on again, and the accurate readings return.

I don't think you heard what I said. Three out of four pickups were fine in this go round, one read bad. I had a similar thing happen a couple of weeks ago, and that was the first time ever.

I'm fully aware of the effects of temperature and these readings were at stable temp having acclimated in my shop for over 48 hours and being measured without handling them. I've been doing this for years, and this has only surfaced recenty.

I wind to turns because I believe it's the best way to get repeatable results. I test resistances and inductances and capacitance because it gives a measure/indication of how I'm doing and if there might be shorts in the coils, etc. In doing so, once in a blue moon it identifies a problem developed in the 11th hour of assembly so it's more than worth it.

This is NOT normal behavior. Not by any means.

To repeat, I measured 4 pickups one after the other ... pickups that had been sitting untouched in my shop for over 48 hours (i.e., acclimated), but which had not been measured since attaching the hookup ... because they needed time to acclimate! Three of the 4 measured according to previous specs ... rock solid with no drifting ... as they always do/should. One read nearly 200 ohms light and "crept up" over a period of a couple of minutes to a point still under what it reads AFTER I replacing the hookup. Post hookup swap, it was stable AT the expected value with NO "creeping". This is normal behavior.

If it was heating due to current from the DVM I'd have seen it years ago. I've been using the same setup for a good 5 years now. I live in Florida, so my A/C runs pretty much year around. It was over 80 outside yesterday, so the inside was the normal 74 degrees that it always is. I suspect something with the hookup, because at least three times now replacing it with older hookup from a different "batch" fixed the problem. Two others I rebuilt completely so I have two "bad" examples in my shop.

I can live with a few bad wires here/there for now, but an alternate source might be nice.

[SkinnyWire]

I did understand what you said. The mystery to me is that you've never run into this before when everyone else has. I don't think that changing sources of hook-up wire is going to make any difference.

It could also be that your meter is a little screwy. Mine gets that way sometimes, I turn it off and turn it on again, and the accurate readings return.

Everyone else has?

If I'd handled the pickups prior to measuring, I'd expect the resistance to slowly drop during the measurement. If for some reason the current from the meter was causing the coil to heat I'd expect the resistance to rise and I'd expect that I'd have seen it for years now. I was open to the meter thing before, but I still believe if it was the meter I'd see it on all pickups regardless of hookup type. I see the "drift" on more than one meter with these cases, so ...

A 200 ohm difference that "changes" with hookup type ... normal? Nope. 99.99% of the time, the final resistance of the pickup is within a few ohms of the sum of the two coils (i.e., within the tolerance of the meter). Add a cover and the AC resistance may go up and inductance down buy the DC resistance stays the same. These cases are outliers for me. If "everyone else" is seeing this, I wonder what "everyone else" is doing different?

[David Schwab]

My pickups don't change their DC resistance once i have them taped and potted. They do when they are still bare and I'm handling them.

I always wind by turn count, and just check the resistance to see if I got a good wind or not.

Interestingly.. hook your meter up and then put a piece of metal by the pickup...

[SteikBacon]

temperature

Has anyone tried to compare a winding made in cold vs. hot environment??? If itīs winded in relative cold things should expand some when it get hotter..

[Satamax]

wow, i didn't know cooler temps could actually bring down the dcr. Hmmm, i'll have to get a thermometer for my basement where i work. I know it gets cooler than 68 degrees down there at times.

Superconductive pickup???

http://en.wikipedia.org/wiki/Superconductivity