Reccomendations for pickup height adjustment?

[RandomHero]

I've finally got the full set of DiMarzio Blazes in my guitar. I'm quite pleased, but admittedly don't have much of a clue when it comes to tweking my sound just how I want it! All of the polepieces, and I mean -ALL- of them on all three pickups are adjustable, of course not to mention to standard height adjustment screws. They're quite hot, bridge mid and neck are 20k, 14k, and 15k respectively, and have ceramic magnets... anyone have some pointers? I don't even know where to begin!

[wolf]

This is not going to be the most authoritative answer but I never adjust the polepieces. As far as pickup height, I try to get those as close to the strings as possible without the distance being too small.

[RandomHero]

That would be a great explanation with a little more definition on what distance is "too small." XD Is there any way to tell if the magnets in my pups are effecting the strings adversely, besides just to listen? These are fairly powerful magnets... some of the highest output pups DiMarzio makes!

[Trey]

I set the polepeices as close to the fretboard radius as possible, and the do a little final tweaking later. I adjust the height of the pickups so that both neither the neck pup or the bridge pup overpowers one another.

If the pickups are to close to the strings they will pull on them and decrease sustain and volume.

[wolf]

RandomHero
To me the "pickup-to-string" distance is too small when the strings start hitting the pickups when you play notes on the higher frets OR when the lower strings start rattling against the pickups when playing very low notes. Yes, I like to get the pickup height that close. And among other things, I have guitars with DiMarzio X2N's in them and those X2N's have HUGE magnetic pull and are the highest output passive pickup there is.

Perhaps the physicists here can help me out (and maybe this might even start a serious debate) but wouldn't the inverse square law apply to pickups? Let's suppose a pickup is 3 millimeters from the strings and you decide this is too close and move the pickups to a 6 mm distance. Wouldn't this decrease the output by a factor of FOUR and not two?

[RandomHero]

The inverse square law does indeed apply to pickups, although I don't precisely remember the inverse square law so I'm going to trust your judgement... I believe that it's "as distance halves, power doubles," which checks out soundly with your math.

My concern is the pickups damping the strings with magnetic pull, as I like lots of sustain.

[wolf]

RandomHero
The above equation is the Inverse Square Law. (That thing that looks like a squiggle means "is proportional to").
The important thing to notice is the exponent ² - showing that power varies as the square of the distance. You mentioned "as distance halves, power doubles". Actually it is "as distance halves, power quadruples".
Returning to the example about a pickup that is 3 mm from the strings, if you want to give it lots of room and drop it down to a 10 mm distance from the strings, then the power would be reduced by a factor of (10/3)² or about 11.1 - quite a drop in output huh?
I'm a tremendous lover of sustain myself. That's the main reason I always set the distortion full-tilt. As far as pickup height affecting sutain, I'd have to agree with you on that. However, think about the bridge pickup. Wouldn't this be the pickup that could be placed as closely as possible to the strings? There is little horizontal or vertical string movement close to the bridge and so the magnet's effect on diminishing sustain would be minimal.
By this reasoning, the trickiest pickup to adjust would be the neck pickup. There is incredible string movement here not just because of the sounds being produced but also the strings have more leeway to move. (Try pushing around a string by putting your finger 1 inch from the bridge. Pretty tough isn't it?)
One thing I have noticed is that when a neck pickup is too close to the strings, you can actually hear the magnet dampening the vibrations (particularly the lower strings). (This vaguely sounds like that climbing arc "bzzzz thing" from the science fiction movies). I believe these are called "wolf tones".
Anyway, I think we've got another topic that will be debated here forever. (Remember discussions about shunting 1 coil of a humbucker to make a coil cut? AND do ground loops really matter that much?)
Yes, pickup height might be the third topic to be debated endlessly here.

[RandomHero]

Hm... definitely useful info. I think I might just have to trust my ear on it. But you're right about the bridge pup, I think, even with a bit of magnetic pull, that's not going to hurt my low B doing it's thing from that close to the bridge! The method that makes sure no single pickup drowns out the others sounds like a good plan, especially in my case where I'll be making a lot of use of the B+N and B+M+N positions. (This guitar now has my -favorite- setup for versatility; an H/S/H with a neck-on switch on the volume pot and a coil cut for both humbuckers on the tone!)

Another question while we're at it. Polepieces - how do they actually change the magnetic feild of the pickup?

[UnklMickey]

wolf said:

One thing I have noticed is that when a neck pickup is too close to the strings, you can actually hear the magnet dampening the vibrations (particularly the lower strings). (This vaguely sounds like that climbing arc "bzzzz thing" from the science fiction movies). I believe these are called "wolf tones".

Really Wolf, I thought wolf tone was something much nicer!
ya know like the sound of a guitar after you had adjusted it!

Seriously though, a wolf tone is an artifact resulting from a resonance in an instrument that is close to but off pitch from the actual note being played.

read more here:
www.cello.org/cnc/tim49.htm

BTW: that thing in the science fiction movies (or my basement when i was a teenager) is called a Jacob's Ladder. -- way cool and visually intriguing!

more on the serious stuff (adjusting height) later.

[wolf]

unklmickey
The only reason I called those "wolf tones" is I read that in a book. (So the book was wrong. Of course I should have checked another source or two).
Incidentally, like you, I have built a Jacob's Ladder and I take it out on Halloween (out of reach of any kids though). The transformer is quite the powerhouse (weighs about 40 pounds) and it can make an arc that will climb 2 feet of #10 wire.
I called it the "bzzz thing" for a reason. In the movie "The Man With Two Brains", Steve Martin is in a "mad scientist's" kind of laboratory. He asks "Where's the beakers, where's the test tubes? You don't even have the 'bzzzz thing"
LOL

[wolf]

Yeah, I could have edited my previous posting but I thought I'd just make a new one.
Anyway, unklmickey, I read the article on "wolf tones" and that is nothing like I described (meaning I sure was wrong).
I also did a search on "wolf tones" particlularly for an electric guitar and they describe "wolf tones" the same way that article does. If that is the case, then I have never heard any wolf tones caused by a magnetic pickup being too close to the strings.

What I have heard is a rapid diminishment of a string's sound caused by magnetic dampening. In a way it is analagous to the spinning of a coin on a table. You know as it gets toward the end of its spinning and it is at about a 45 degree angle and the energy starts to die out? Now imagine putting your finger on the coin and squashing it flat. To me, that is the effect I have heard. As I said too, it makes a strange noise as the string suddenly dies out. (Kind of like the "bzzz thing"). It seems I may have been one of the few people that might have heard this phenomenon. (Wait ... that's "Scientific American" on the phone right now) ;D

[TooManyWires]

Regarding the inverse square law discussion:

It's been about a half a year or so since I've touched any of that kind of stuff so don't take this as a be all and end all answer in any way, but it seems to me that that can't be true. That would mean that you would have to notice an incredible change in volume based on the height of your pickups, like you said, a change of 7mm could drop your output power by a factor of 11.1

Now, given that a humbucker might have an output of around 10 (henries?...I think thats the unit they use...or mH..or something like that...or mV maybe...yeah...maybe mV..) anyways....10 units...that would drop your output down to about 1 unit..a little less actually but for the sake of simplicity. So, if with an output of 10 you made a sound of say....100 dB (uhm...I think that's roughly equivalent to sitting in the front row of a loud rock concert)...that means that your signal would now be about 10 dB..(which is the threshold of human hearing) (Assuming linear response from your amp...which may or may not be true, I personally have no idea, I know you don't get linear response from your ears....thats logarithmic (ie- you hear doubling the dB level as increasing in volume by a factor of 10)). That means that your signal would be barely audible even through an amp, or else you'd have to turn your amp way up past it's normal volume in order to hear your guitar. (Or, alternatively when you plugged in you'd get your face blasted off from the increase in volume.)

I know personally from some basic experimenting after replacing a pickup that this isn't true. I adjusted more than 6 or 7 mm in height and didn't notice any drastic volume change like that. I can't say I really remember noticing any volume change really.

My guess would have to be that output and power aren't the same thing. Output and volume might not be the same thing either. Output might be related to the "hotness" of the pickup (if I might use such a made-up word). Output might be like resistance in so far as a pickup with a higher output would distort quicker in much the same way as a higher resistance pickup would distort quicker.

Now, again, I'm really not an expert in this particular area of physics right now, so this could all be way off, and I wouldn't be all that surprised, but I think that the inverse square law can't apply to pickups otherwise you'd notice miniscule changes a lot more. The difference between playing an open note and fretting on the high frets (22-24 sort of thing) would be probably be...1 or 2mm depending on your action? And that means that you'd be getting the difference between say...6mm and 4mm...which would then look like (6/4)² = (36/16) = 2.25 So that means you be over twice as loud on a high fret as you would be on an open fret....and that isn't true. Although there would also be differences in the displacement of the string from it's two furthest points from equilibrium at the 24th fret versus open string, so that would also affect volume, (I think, that's why the bridge needs more output than the neck, isn't it?...or part of the reason, anyways, I think..) So, I'm really not convinced that that rule would apply to guitar pickups. I think that the "power" in the inverse square law is something entirely different than the "output" of a guitar pickup.

If I went and looked this up in my notes and stuff, I could probably come up with an answer. But I'm just not doing that now, so I'll just wait for someone smarter than me to come along and correct me. There was a guy on GN1 who was an electrical engineer and he answered a whole whack of technical questions like this...Chris I think was his name....or Eric...something...he would know the answer to this, if he's on GN2 here, help us out, would you buddy?

Anyway, my recomendation regarding pickup height is just frig around with it a bit, then play for a while, then repeat that procedure, and see what appeals to you and then leave it there. If you adjust the pickup "too high" it won't hurt anything...it can't break a string from the magnetic pull or anything, and if you adjust it "too low" it's not going to hurt anything either. Worst case scenario (and...no offense intended if this has happened to anyone, but you'd have to be fairly lacking in the common sense department to pull this one off), would be that you adjust the pickup WAY too high, and the strings touch on it when you fret them, and then you continue to play for a while with it adjusted like that and you might get some scratches on the pickups. Other than that, I really can't see too much going wrong, maybe if you adjusted them too tight, you might crack or break the plasic mounting ring, but you'd really have to crank on them to do that. And you don't even have to take anything apart to adjust the pickup height, just need a screw driver. So, I'd say figure out each pickup one at a time until you get each one the way you want it, and then flick through them in all your combinations and then adjust them enough to make them mix properly.

So thats my thoughts...don't rely on them to prove anything, theyre just what I thought when I saw the question. And sorry for the long post, I kind of talked it out as I went...

[wolf]

TooManyWires
Henries are a measure of inductance and not of output (which I think is measured in volts).
I beleive you are correct in saying that "you don't get linear response from your ears....thats logarithmic (ie- you hear doubling the dB level as increasing in volume by a factor of 10)."
Plus, decibels are logarithmic:
www.absoluteastronomy.com/encyclopedia/d/de/decibel.htm

Yes, I think this discussion could get bogged down if we bring in even more technical information. (and I'll admit I started it). Basically I agree with your principle of pickup height adjustment: "just frig around with it a bit, then play for a while, then repeat that procedure, and see what appeals to you and then leave it there".

[RandomHero]

Okay, here's something I noticed from my frigging around. XD

Does it make any sense for there to be far less noise if the pups are closer to the strings? It only makes a bit of sense to me as to why, but I never considered the grounded strings to be -that- much of a sheilding.

[UnklMickey]

admin said:

Okay, here's something I noticed from my frigging around. XD

Does it make any sense for there to be far less noise if the pups are closer to the strings? It only makes a bit of sense to me as to why, but I never considered the grounded strings to be -that- much of a sheilding.

i wouldn't think strings would make much of a shield either.

do you have a metal pickguard? moving the pups in relationship to the plane of the pickguard could affect the amount of noise. or are you comparing the noise to the signal? if you turn up the volume a bit to compensate for the lower signal when the pups are further away from the strings, you also turn up the noise.


i like Trey's idea of using the fretboard radius as a guide to set the pole-piece heights, especially for the neck pickup. at the bridge, the bridge radius (if its curved) or straight is probably better.

another direction for experimentation: i think you'll get a much different sound from a pickup if the pole pieces from one coil are considerably higher than the other vs. both being the same height.

one thing that won't work well: having the pickups extremely low and having the pole-pieces extremely high. you get a strong magnetic pull on the strings, but the coil is far enough away that you don't efficiently couple to the coil.

if you decide to recess any of the pole-pieces, be careful! on some designs the magnets extend beneath the screws. if you feel resistance stop. (i didn't heed this advice in regards to cleaning my ears with a Qtip and the rest is history :lol: )

Wolf, sounds like Halloween at your house must be totally outrageous for the neighborhood kids!

[ajent__smith]

scince the whole pickup pickup picks-up sound, wouldnt the square law apply relative to the middle of the pickup, not the top. so if your pickup is 10mm high. for example dubbleing the distance of 3 mm would be 11mm ((3mm+5mm)*2)-5mm=11?

[Mustang]

I ran across this article and thought it broke down the theory pretty good.

" The magnetic field lines (produced by the magnets) flow through the coil(s) and a short section of the strings. With the strings at rest, the magnetic flux through the coil(s) is constant. Pluck a string and the flux changes, which will induce an electric voltage (actually a currert) in the coil. A vibrating string induces an alternating voltage at the frequency of vibration, where the voltage is proportional to the velocity of the strings motion (not its amplitude). Furthermore, the voltage depends on the string's thickness and magnetic permeability, the magnetic field, and the distance between the magnetic pole and the string."

This makes sense to me.

[bam]

There is something I'd like to share. This thing happens when the 1st GN was still running.

I like Dimarzios; but when one day I adjust the polepieces, suddenly I got an extreme level of feedback. I (until now) believe that it was caused by ringing polepieces; when you raise the polepieces' height, it takes away its factory potting, and plus, its contacts with the magnets are lessened, thus increasing its "ringability".

The reason why I believe in that theory (hypothesis) is that when I return the polepieces' to the factory default position (all down to their lowest height), the (unwanted) feedbacks are gone.

Hope this could help.