DCR Reading of Parallel Pickups

thegummy

I forgot exactly how I wired up my Strat and want to find out without taking the pickguard off.

The bridge pickup is coil-tapped and a switch changes between tapped and full, I'm just not sure which one is up and which one is down.

So when the pickup is in parallel with another one (position 2 for example), would a higher or lower DC resistance reading indicate that the pickup was switched to full output?

WezV

Lower. - edit - higher  

With 2 coils of 5k each, you get 10k when wired in series, and 2.5k when wired in parallel.

With 3 coils of 5k each you get 15k in series, but 1.7k when wired parallel.

If you had 2 coils as a series humbucker with a parallel wired single coil you would get 3.3k


You can use a parallel resistor wiring calculator to figure it out if you know the approximate readings of each pickup/coil

mart

What @WezV says is correct, but I think misses the exact question you're asking. I think he's comparing parallel pickups with individual pickups, whereas you're asking about tapped vs untapped, right?

If you get a higher resistance, then you're seeing the full, untapped pickup, whereas a lower resistance means you're seeing the tapped pickup. 

That will still be true even if the pickup is in parallel with another - still the tapped reading will be lower than the untapped.

WezV

yes, i misread the actual question  

My first example is your tapped humbucker with single coil in parallel (2.5k if both coils are 5k).  My 3rd example if your untapped series humbucker with single coil in parallel (3.33k if all coils are 5k)

you can still use the calculator with your actual coil/pickup values to figure out what each setting should actually be

ICBM

mart said:

That will still be true even if the pickup is in parallel with another - still the tapped reading will be lower than the untapped.

Correct. It will be a smaller difference than for the bridge pickup by itself, but the split setting will still be lower.

Funkfingers

WezV said:
tapped humbucker

I read the question differently. (Humbuckers not mentioned directly. To me, tapped bridge pickup = single coil, such as an OCP Diamond Geezer or the equally Gilmourish Seymour Duncan SSL-3T Hot, Tapped.)

Either way, if the selector switch is configured to automate the "tap" when the bridge and centre pickups are combined, the "tap" mode switch will make no difference.

WezV

you might be right, I just expect people to mean a split/shunted humbucker when talking about a coil tap, even though I know the terminology is technically incorrect.   Not like its unheard of for guitarists to adopt an incorrect term and run with it  

Funkfingers

Yup.

If it were me, I'd treat the Stratocaster to a string change. Use the opportunity to raise the pickguard and either photograph or sketch the circuitry.

thegummy

Funkfingers said:

I read the question differently. (Humbuckers not mentioned directly. To me, tapped bridge pickup = single coil, such as an OCP Diamond Geezer or the equally Gilmourish Seymour Duncan SSL-3T Hot, Tapped.)

Either way, if the selector switch is configured to automate the "tap" when the bridge and centre pickups are combined, the "tap" mode switch will make no difference.

It is a tapped single coil, and is in fact an OCP Diamond Geezer.

On the bridge alone setting the DCR is almost halved when the switch is engaged and the difference in sound is night and day so I wouldn't have needed to measure that one anyway.

But in position 2 the sound difference is very subtle to the point where I wasn't sure if it was auto-tapped or not. When I used the meter there was a difference of about 1 or 2K between the switch being on or off and I wasn't sure if the higher or lower of those would mean the full position so thanks to everyone who's confirmed it's still the higher number that's the full coil, even when it's in parallel with another pickup.

Funkfingers said:

If it were me, I'd treat the Stratocaster to a string change. Use the opportunity to raise the pickguard and either photograph or sketch the circuitry.

I actually plan on rewiring it a bit at some point, that's why I was avoiding lifting the pickguard (and wasting a set of strings really). I usually keep up to date diagrams of my guitars' wiring but the one I have saved now definitely doesn't match the guitar. I had a really bad illness this year which has caused a bit of memory loss for some of the year so I've either re-designed the diagram and not got round to actually changing it on the guitar or I've changed the guitar and not updated the diagram.

ICBM

thegummy said:

On the bridge alone setting the DCR is almost halved when the switch is engaged and the difference in sound is night and day so I wouldn't have needed to measure that one anyway.

But in position 2 the sound difference is very subtle to the point where I wasn't sure if it was auto-tapped or not.

The sound won't change much, especially if even the tapped bridge pickup is higher-wound than the middle pickup - the lower-impedance pickup dominates the parallel mix, so what you hear is mostly the middle, with a bit of harmonic cancellation from the bridge pickup.

The same is true with my PRS Swamp Ash Special (HSH) which I've added extra switching to - in the 'in-between' positions, there is little difference between the full humbuckers and the split coils. It's there, but subtle - because the middle pickup is a Duncan Vintage Rails, which has a very low impedance so the sound is almost unaffected by which mode the humbuckers are in.

This is accidentally very convenient, since it means I can get 'Strat' sounds by engaging the middle pickup switch, regardless of how the coil split switch is set.

Funkfingers

thegummy said:

It is … an OCP Diamond Geezer.

On the bridge alone setting, the DCR is almost halved when the switch is engaged and the difference in sound is night and day so I wouldn't have needed to measure that one anyway.

I have an OCP DG pickup, obtained in one of Ash's workshop clearance sales. Mine was a "customer changed his mind at the last minute" example. Equal length rod magnet polepieces and 10/15k coil readings. Thus, my experience with pickups of this name is non-standard.

thegummy

ICBM said:

The sound won't change much, especially if even the tapped bridge pickup is higher-wound than the middle pickup - the lower-impedance pickup dominates the parallel mix, so what you hear is mostly the middle, with a bit of harmonic cancellation from the bridge pickup.

I'm surprised at this, I would have expected the hotter pickup to dominate if either but that's why I asked this question, my knowledge of the electronics behind parallel pickups is poor.

What you say confirms my experience with the tap in position 2, in that it doesn't really affect the sound much.

Crossing over to my other thread about the push-push and S1 switch, I think the fact that I've realised I only need to be able to switch between tapped and full output when in the bridge-only position will make it easier for me to use the same switch for the coil tap and the bridge-on function.

normula1

@ICBM is bang on. I've just put it a single coil sized humbucker in one of my Strata and position 2 is very similar if the bridge is (partially) split or not

ICBM

thegummy said:

I'm surprised at this, I would have expected the hotter pickup to dominate if either but that's why I asked this question, my knowledge of the electronics behind parallel pickups is poor.

You would instinctively think so, but it’s usually the other way round - it’s the load each pickup sees from the other one that matters. A higher-impedance pickup doesn’t put as much load on a lower-impedance one as the other way round, so the lower-impedance (usually ‘weaker’) pickup dominates.

If the higher-output pickup is achieved with a more powerful magnet rather than a higher-impedance winding, it can be more dominant though.

Funkfingers

FWIIW, yesterday, I chucked my OCP Diamond Geezer and two overwound Stonetones into an MIM Stratocaster for test purposes.

The OCP DG is in tapped mode, so, approximate DCR meter readings are 10/8/8k whereas the regular versions would be 9/7/7. 

The centre and tapped bridge combination is nice. Drive and quack in equal measure. Pretty much as Ash describes.

I shall test the centre and full output bridge combination but I do not anticipate it being as good.

The MIM Strat has the seven sounds switching mod. Neck and tapped bridge in parallel was interesting but with no serious allusions to Telecasterness.

I am tempted to retain the existing wiring, with the OCP DG in tapped mode, then, add the full output mode on a "blower" switch.

thegummy

Funkfingers said:

FWIIW, yesterday, I chucked my OCP Diamond Geezer and two overwound Stonetones into an MIM Stratocaster for test purposes.

The OCP DG is in tapped mode, so, approximate DCR meter readings are 10/8/8k whereas the regular versions would be 9/7/7. 

The centre and tapped bridge combination is nice. Drive and quack in equal measure. Pretty much as Ash describes.

I shall test the centre and full output bridge combination but I do not anticipate it being as good.

The MIM Strat has the seven sounds switching mod. Neck and tapped bridge in parallel was interesting but with no serious allusions to Telecasterness.

I am tempted to retain the existing wiring, with the OCP DG in tapped mode, then, add the full output mode on a "blower" switch.

My Diamond Geezer reads at about 8k when tapped but I pair it with pretty weak neck and middle pickups - Alnico 3 based ones that read about 5K (Bare Knuckle Apache). I still get nice sounds with neck+bridge and middle+bridge, maybe not as nice as it would be if the pickups were closer in output.

Something I need to decide before rewiring is whether to have the tapped or full output as the default. I'm thinking the full output as I think that it's when playing lead that I'm more likely to want to switch between pickups in the middle of playing (and I like the full output for lead) whereas with bridge I think I'm more likely to stick on the one setting.

Dave_Mc

^ I spent ages (oh alright, it was probably around 45 seconds) trying to decide which output I wanted as the default on my Strat with tapped singles, and then proceeded to wire the push-pushes backwards...  

thegummy

ICBM said:

thegummy said:

I'm surprised at this, I would have expected the hotter pickup to dominate if either but that's why I asked this question, my knowledge of the electronics behind parallel pickups is poor.

You would instinctively think so, but it’s usually the other way round - it’s the load each pickup sees from the other one that matters. A higher-impedance pickup doesn’t put as much load on a lower-impedance one as the other way round, so the lower-impedance (usually ‘weaker’) pickup dominates.

If the higher-output pickup is achieved with a more powerful magnet rather than a higher-impedance winding, it can be more dominant though.

Is there anything that can be done with wiring to improve the "both" sound when one pickup is quite a bit hotter than the other?

ICBM

thegummy said:

Is there anything that can be done with wiring to improve the "both" sound when one pickup is quite a bit hotter than the other?

It’s difficult. You can add a small resistor in series with one or both pickups to stop them interacting as much - a simple passive mixer basically - but that tends to make the sound weaker overall.