60 cycle hum question
 

Guys, I'm confused...

To start with, the bass being used: 2012 USA Fender Jazz Bass w/ CS60s pups

I understand that 60 cycle hum is different than the high pitched one that you can stop by placing your hand on your strings. But my ears seem to think they're related :hiding:
When I play somewhere with really bad grounding hum (the high frequency one that you can stop by touching metal), my 60 cycle hum seems to also get much much louder. And contrarily, last night I played somewhere and had no extra noise whatsoever when I wasn't touching my strings. And similarly, I swear I couldn't even hear a 60 cycle hum at all. We were turned up quite loud too. I was playing through a GK 2001RB (not my amp)

Why do my ears think that they're related to one another? I was on this mad hunt for hunt for hum canceling pups that sound just like single coils... As many of you know, this is a tough task because there's no such thing. So, I'm wondering, should I just get the damn bass shielded first and see what that does?

They are not always related but they can be. Some types of electronic devices generate harmonics of 60 Hz out to frequencies higher than the ear can hear. So you can hear high frequency buzz from some 60 Hz devices. If you had a way to capture it and display it on a spectrum analyzer you would see that it is a "picket fence" of frequencies spaced 60 Hz apart. And high frequencies can be transferred via capacitive coupling more efficiently than low frequencies so if the source device does not generate strong magnetic fields that can couple the fundamental and low harmonics of 60 Hz to your pickups you can hear the high harmonics via capacitive coupling. For one reason or another putting your hands on the strings can disrupt capacitive coupling (through your body??), especially if the strings are grounded through a bridge ground wire.

Ken

... so would shielding the bass help with the hum I get when my pups aren't at equal volume? (Not expecting to eliminate it, just lessen it... significantly, if possible)

shielding the bass is never a bad thing, and will likely reduce interference injected into the bass wiring but its not likely to reduce the 60Hz hum from the bass pickups.

On the topic of noise cancelling sc pups.. consider this.. imo if you always run the pups at equal volume to avoid the hum then you are missing out on 80% of the possibilities with true SC tone anyway, so just pick a set of noiseless and go for it :)

might have to go with the DiMarzio Area J pups then... but first we'll shield it and see what that does.

I usually run bridge 100% and neck 50-75% as needed

That's it! I've had it! I'm at a gig now... The hum is so loud. I just can't take it.
I'm getting humbuckers

Usually I'm with you. I put SCN humbuckers in my Deluxe V. But I also love single coil tone! It's the way life works. I left my SX basses single coil.

Here's quick lessons.

There are two types of hum. Electric hum and Magnetic hum. Electric hum comes from noise being capacitively coupled to your body and into the bass. This is the hum that goes away when you touch ground (strings are grounded through the bridge). This is the kind of hum that can be nearly eliminated by proper shielding of the bass. You want to enclose ALL electronics (except tops of pickups, of course) in a continuous grounded conductive box. Copper foil works best but is more work to do. Once this is working right touching ground will have NO effect on hum (and related higher frequency 60 Hz harmonics noise)

Note that while Fender basses are typically shielded (with conductive paint) sometimes their shielding leaves much to be desired.

The other Hum is magnetic hum which comes from single coil pickups. This hum DOES NOT change when you touch ground. Humbucking is the only way to get rid of it. Usually this means two pickups one wound one way and the other wound opposite to cancel hum pickup. To make the signals from the strings back in phase, the magnets on one pickup are reversed. The pair of jazz pickups are like this. Thus when both pickups are on full (or at equal levels) they form a humbucking system. When you solo either of them you have single coil and hum sets in. The way you test for single coil hum is that while touching ground won't change hum, by moving the bass around into different orientations (some of them unplayable) you can find an orientation where the hum is "nulled" and is reduced. Humbucking pickups are the ONLY cure.

Note that to have humbucking with a Jazz type pickup you need to split the pickup into two coils somehow. Usually this is by winding two coils side by side so that sort of like a P bass one coil pick up two strings and the other half picks up the there two. Another version known as "stacked coil" uses two coils stacked one on top of the other where one coil picks up strings and the other only picks up hum. In either case these changes greatly mess with the normal inductance of the pickup. In the former it makes it much less and in the latter it makes it more. That is why the humbuckers never sound quite like single coils in passive basses! There are more exotic pickups that cancel hum like "sidewinders" that use diferent configurations but they usually don't much sound like single coils.

What to do about this is up to you. My advice is to first shield your bass until touching the strings does NOT change the hum level. THEN decide what you can live with. it's what I did. I say this because I found that once you get rid of the hum that stops when you touch ground the single coil hum, while still there, just somehow isn't as annoying.

I've narrowed it down to DiMarzio Area Js (for being financially responsible), Nordy NJ4SV, or Fralin split coil.
I have no clue how to narrow it down further...

There's a guy on here that posted an interesting wiring diagram where you run both pickups in series to create the humbucking effect, yet he has a volume control on the pickups...memory is failing but I think ONE pickup had a volume. It was very interesting. I had to draw his schematic on a piece of paper and analyze it, and yes, it makes sense that it can work. I think it was walterw but not sure, as there's a few pretty sharp walters on here. I'll do a search for you as soon as I post this.
Fender did some pretty sharp marketing when they introduced 'noiseless pickups'. There ARE no noiseless single coils (unless you put them in series).

Here's the link. I was right; it was walterw, but unfortunately you'll lose the single coil sound. Still cheaper than buying new pickups:
http://www.talkbass.com/forum/f38/wi...series-936582/

I would put in the brass grounding plates in both pickup cavities and wire them to the pots. Shielding paint or copper foil will also help but I promise you will notice a difference with those brass plates if they are properly installed. You might decide to keep those single coils after trying them if properly grounded. Cheap too. Lots of great pups, but you're not getting the most from what you have. You will likely have to run a wire from each pot to the next then to the the ground on your jack - your jack likely only has the tip connected. Check it out. Go old school...it works!

although wiring in series does give a different tone, this really has no effect on hum.. both pickups would need to have the same output to cancel hum.. series or parallel doesnt matter..

Good shielding (including the pickups) and proper grounding can get rid of 60% of the hum, and that may be enough for many and not enough for others. If both pickups are turned to the same volume, then they buck hum.

If you like the bridge full and the neck at around 1/3 less, you might be able to approximate that tone by lowering the neck pickup to reduce output, and then be able to put the volume up all the way on both pickups.

right; that series wiring thing makes for a big and boomy tone, but turn one pickup down and the hum comes back again.

Dude, the Fralin split coils are hard to beat. The tone is amazing! I think that they still sound like single coils, because the magnetic field isn't changed for each individual string (i.e. only one pole per string). With the Fralin's I can solo the neck pickup, which I frequently do and no hum! :bassist:

I haven't heard or played the DiMarzio's, but they add another pole for each string which logically seemed like a deal breaker to me. Seymour Duncan also does this, they call it stacking, one pole on top of another. I am curious how they sound.

huh?

did you mean "one coil per string"? the poles are the magnets themselves.

if so, then the dimarzios are just like the fralins; it's the duncans that stack two coils (and have a quieter, weaker sound as a result).

I put DiMarzio DP123 Model J pups in my MIJ jazz when I just couldn't take the hum any more. Excellent results and excellent tone.

Now that I have...ahem...a few J basses, I am learning to either embrace the hum or keep the volume controls even. Can't afford to go with 'buckers in all of them and the '62 AVRI would probably have a stroke if I did. The stacked V/T arrangement works very nicely on the '62, so you can dial in a particular tone while keeping equal gain on the pups. No hum.

Then again, I only play out at church and I use a P Lyte there. I could see how a gigging bassist might be ready to do something drastic.

I've got some DiMarzios and I like them (especially for the price), but my all-time choice for best are Nordies. But definitely not financially responsible!

Yep. With Fender's S-1 switch, however, the bridge pickup's volume is disabled when the pickups are in series, so the neck volume becomes a master volume and it's humbucking at all times. I think that's cool, because you can more easily compensate for the series volume boost on stage, but Fender may have done this to make it more like a P-bass when in series mode.