I am wondering if there is a difference between neck pickup and bridge pickup? Are both Humbuckers the same? I have already done the wiring loom and have assumed both are the same from a wiring viewpoint.
Wiring yes, but the bridge pickup should have more windings on it than the neck pickup, to make up for the fact that the string amplitude at the bridge pickup position is less than at the neck pickup position.
If both pickups were exactly the same, then you'd get a lower output from the bridge pickup. So the bridge pickup in a matched set normally has around 10% more windings on it to increase the output so it's similar to the neck pickup. As more windings = more coil resistance, if you measure the pickup resistance with a multimeter, the bridge pickup should have a higher resistance. Because the pickup is a coil, has resistance and also has some capacitance, the actual resistance at audio frequencies will vary according to frequency, so the multimeter reading, which used a small DC voltage to measure the resistance, is known as the DC resistance, or 'DCR'. This is the figure you'll see quoted when people say 'This pickup measures 9.8k', or 'This pickup measures 14.5k'.
In general, a higher DCR indicates more output (it also depends on the magnet type used). But the coil wire size also comes into play here. Most vintage spec (and many other) pickups use 42AWG wire. But a coil bobbin can only accommodate so many turns of wire on it before it's full. So to get more turns and more output, you use thinner wire. Higher output pickups often use 43AWG wire, and some really high output pickups even use 44AWG wire. The bigger the AWG (American Wire Gauge) number, the thinner the wire.
Whilst different manufacturer's wire has slightly different resistance figures per unit length, on average, going up an AWG number increases the wire resistance by an extra 27%. So if we have two pickups with the same number of turns as each other, but one has 42AWG wire and one has 43AWG wire, then the output will be the same but if the 42AWG one has a 10k ohm DCR, then the other will have around a 12.7k ohm DCR.
As thinner wire is more fragile and more likely to break when being wound, manufacturers normally use the thickest wire they can, so the thinner wire is normally used on the hotter pickups that need more coil turns.
So, you need to consider this when comparing pickup DCRs and you really need to know what gauge wire the pickup has been wound with if you are trying to work out how much extra output one pickup has over another. A 42AWG 8.2k DCR pickup may seem to have a lot less output than another one quoted at 11.2k, but if the 11.2k pickup is a 43AWG one, then the increase in output isn't 40% as it may first appear, but 10%, as (allowing for the higher wire resistance) it's equivalent in the number of turns it has to a 42AWG pickup with a 9k DCR.
Comparing DCRs is not an exact science, as there are other factors to consider, but it is certainly indicative.
So, if you have two otherwise identical looking pickups and you want to know which one is best in the neck position, get a multimeter, measure the pickup resistances and the lowest DCR one will be best suited for the neck position.
If they get installed the other way round, then nothing catastrophic happens, but the neck pickup will have more output than the bridge, so they won't sound very balanced, and you'll need the bridge pickup set close to the strings and the neck pickup set away from the strings If there is an imbalance, it's more common for the bridge pickup to have more output than the neck pickup. The classic humbucker combination of a Seymour Duncan JB in the bridge and a '59 or a Jazz in the neck position is like that.
The kit humbucker pickups I've measured are generally a well-matched set, with one pickup having a DCR that's 5-10% greater than the other. They are generally on the powerful side, with a DCR in the 9-10k area and their ceramic magnets up the output compared to the alnico magnets you'd find in a more vintage-style humbucker. So I've always gone for aftermarket pickups where I've got the choice of how they sound.
Thanks for that, looks like I fluked the right pickups in the right position. The wiring diagram I have is called "alternative 2 humbucker,4 pots, 3 way switch diagram. Is there a standard (not alternative) diagram? If so what is the difference?
The other is for a Les Paul/SG style arrangement where each pickup has its own tone and volume control. The Gretsch-style wiring has a volume per pickup, then master volume and master tone controls. Same number of pots and switches, but a very different arrangement of them. With the distributed pot locations on the GR1-SF, the LP style wouldn’t work that well (though if you never use the tone controls, then it could be an option).
Thanks for all your help. My build is going well, very pleased with the True Oil finish after 8 coats. Having problems with my wiring??
I have used shielded wire and earthed the wires where possible. I have no signal to my wiring loom from the test amp. Tried the amp with another guitar and it works perfectly. There is no signal at the input, no buzz when I touch the end of the input plug. I have checked my wires a number of time and it seems ok. There is nothing happening at both pickups when I plug the loom in. I checked the wires with a multimeter and they seem to check out ok. I suspect there is something simple wrong??? Any suggestions?
It’s either a missing wire, a signal wire touching a ground connection or a bad solder joint.
Measure the resistance between the signal and ground connections on the jack socket with no jack plugged in. With no signal, it’s either going to be no resistance (a short), or an overload reading (open circuit).
Given that you can touch the tip of the jack plug when it’s plugged in with no buzzing, then it sounds like a signal short to ground. Check with the selector switch in all three positions.
First just double-check that you have all the volume pots turned up fully, including the master volume. I’ve tested for a short circuit before only to find a pot was turned down, not up!
Then look for loose wire strands at solder joints reaching across to touch a grounded item, like a pot casing. Is a signal wire poking through a pot tab too long and is touching the pot casing? If you’ve used push-back braid shielded wire, then has the braid slid forward so it’s touching a connection (I’ve had that before as well). And is a braid shield touching a signal connection?
If everything else checks out, then I’d suspect the selector switch may be faulty. Those box switches are fine when they work, but when they fail they tend to fail completely and short all the signals to ground. And of course you can’t see the workings (which is why I much prefer the open-style lever switches). You’d want to unsolder the wires to it to test if any of the switch contacts were internally connected to the ground tab and the central signal connection was switching correctly to the outer connections.
Post pictures of the wiring and we might notice something obvious. Try and get the pot and switch connections clearly shown. If they are covered up by wiring and we can’t see any soldering details, then it doesn’t tell us anything.
If the pots don’t work well, then note that the wiring diagram shows the ‘ground’ tab on the pots folded back and touching the pot casing but there’s no red blob indicating they should be soldered. Those folded back tabs should all be soldered to the pot casing. Either directly, or using a piece of wire. There should be a wire connected to ground going to the back of each pot. Not all pots have tabs that are long enough to bend back to reach the pot casing, so I generally use some wire to connect them regardless.
Posting Permissions
Reply With Quote