The only thing that affect the tone of a bass is the pickguard. Tort or no tort is where it all lies.
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Does pickup height affect tone?
- Thread starter monkeyfinger
- Start date
Helmuth Lemme wrote a great book that gets into the nitty-gritty of pickup design that's well worth reading by anybody who wants to know what's really going on electronically with pickups and passive instrument wiring. It's been mentioned in several places on TB over the years. It's called: Electric Guitar Sound Secrets and Technology
Here's the Invalid Link Removed with the full description and TOC. Sample here (and it may be all you need or want to read.)
Important - The English language edition periodically goes out of print. And when it does, the jackals all start showing up on EBay and Amazon asking ridiculous amounts of money for this book. DO NOT buy it if anybody is asking more than the current exchange rate for €34.50 - which is a few pennies shy of $36 USD as of today. I just saw one jerk asking over $200 for a copy claiming it was "rare and out of print." It's neither. You sometimes just have to wait a few months for another press run in order to buy a copy at normal prices.
Here's the Invalid Link Removed with the full description and TOC. Sample here (and it may be all you need or want to read.)
Important - The English language edition periodically goes out of print. And when it does, the jackals all start showing up on EBay and Amazon asking ridiculous amounts of money for this book. DO NOT buy it if anybody is asking more than the current exchange rate for €34.50 - which is a few pennies shy of $36 USD as of today. I just saw one jerk asking over $200 for a copy claiming it was "rare and out of print." It's neither. You sometimes just have to wait a few months for another press run in order to buy a copy at normal prices.
I'm not at all trying to imply that your conclusions are incorrect, but I am very interested to know exactly what data you based your conclusions on. Did you measure string tension low vs high pick up? The other way, I assume, would be to measure intonation with a very sensitive strobe tuner low vs high pick up. In both cases, I'm not sure I can envision a rather weak magnet pulling with enough force to bend a rather fat and taught bass string. Also, if this were the case, I imagine raising or lowering the pickups would then require an intonation adjustment, which I've never had to do in the past. But like I said, I'm interested in hearing about your data.
- Jun 6, 2012
- 4,837
- 6,859
- Disclosures
- I don't wait 30 minutes after eating, to go swimming.
Setting pickups too high can cause a number of unusual occurrences. Depress strings at last fret. Using a 6" (150 mm) ruler, measure the distance from the bottom of the first and fourth strings to top of the pole piece. A good rule of thumb is that the distance should be greatest at the fourth-string neck pickup position and closest at the first-string bridge pickup position. Follow the measurement guidelines from the chart below as starting points. The distance will vary according to the amount of magnetic pull from the pickup.
Note: Larger string gauges need wider vibrational allowances. If you have a five-string bass or are using heavier-gauge strings, your measurements must be increased accordingly.
You can also use a set of precision dimensioned non magnetic rods (brass, etc.) and use those to set the coarse gap between the pickup poles and the strings. StewMac and other suppliers have them. They look like brass Allen keys minus the ridges.
Then comes the 'art' part since no two pickups are exactly the same - and different strings have different characteristics. Once roughly adjusted, I'll make minute adjustments (an eighth turn or less) in the height adjustment screws, then play and listen. Then repeat as often as necessary over a few days until I hear what I'm listening for and the strings respond the way I want them to on that particular bass.
It's time consuming and very personal - so I'm not surprised nobody but the boutique shops spend much time doing it. But I've often maintained the single biggest difference between a high-end boutique bass and your average good quality instrument is that boutique builders take the time to absolutely nail the entire setup on their instruments.
Wood is wood. Electronics are electronics. Strings are strings. It's the selection and combination of quality materials, and especially the attention to all the details of the craft of bass building that separates the truly great bass from the merely excellent ones. And pickup height is one of those details.
^This! This!! A thousand times this!!!
I've been arguing the very same thing for years. People can get so bogged down with things that make a barely (or most times no) audible difference - yet paradoxically be totally blind to something that's simple and easy to adjust (like you action or pickups) which can make a huge difference.
(Thx SL.)
Yes, it's a fine irony that in doing so people are very willfully ignoring the most obvious solution - the one that involves the primary cause & creation of the sound in an electric instrument; the transduction of vibration to sound via the interaction of pickups and strings!
Some can very credibly argue this is the sole non-human factor. Others prefer to believe in the unlikely perceptible or the physically impossible, no matter how many videos people post of instruments made of stainless steel bodies and neck that sound warm as a roaring fire surrounded by sexy ski bunnies in a mountain lodge.
My belief is it's because doing a setup doesn't involve talking or shopping, or posting while at "work", which is primarily what this site is about.
Truly everyone really *should* learn to do their own setups! There's no sense in paying someone to keep your instrument for a few days or a week to do something you can much better do yourself within a very short learning curve. Put that travel time and setup cost into a lesson and focused practice instead and your tone will greatly improve.
My conclusions were based on a data set which included measuring the magnetic field at the string for various distances to the pickup poles using different kinds of pickups (different magnet structures, etc) and using a strobe tuner to look at the effects of magnetic strength on pitch; as the magnets got closer to the strings, the pitch was pulled up, indicating that the magnets were increasing the string tension by stretching them sideways.
By what standard do you judge a "weak" magnet, or a "fat and taught" bass string? You might be surprised at how strong the magnetic strength is close to the pickup, and the more ferrous mass the string has (i.e. the fatter it is), the stronger the lateral pull on the string.
What it boils down to is that you can set the "optimum" pickup height with a strobe tuner. The funny part is that after I did all that, I was talking to a very well-known pro guitar tech who was genuinely flabbergasted that I had figured out that "top secret" info about setting pickup height. It's just physics.
It's funny, but I once got hired for a recording project (soundtrack for a truly godawful indy horror movie that never got completed) partly because when asked where I brought my basses for their setups, I told them (truthfully) I did my own.
They seemed to feel (one of the producers was a recording engineer as well) that that showed I actually listened to what I sounded like. So if they asked me for something, I'd be quick to deliver. They figured that would save them major time and money on their tight budget.
Who knew?
That's pretty interesting. Strobe tuners I'm familiar with. What sort of test rig did you use to measure the magnetic field. Are we talking several thousand dollars worth of lab gear? Or something affordable that uses the power of a PC to get that info?
If you look at the Helmuth Lemme excerpt I posted above, he has a device which seems to do something similar.
I've learned something new here today, thanks! Now I'm curious as to how many cents the magnet can pull a string out of tune. This is interesting stuff.
Would you say then say it is likely a combination of a changing harmonic spectrum ratio coupled with nodes moving / changing pitch due to the pull of the magnet that causes the tone to become dissonant?
I used a Hall-Effect Magnetometer. I don't recall the model, but it was probably $300-400 or so, if I recall. It was a tool we used at a former employer, though I still have it as it was in the "abandon" pile when they closed up our office, laid us all off, and left town with the equipment they wanted to keep. (A very large and well-known company - nothing fishy. They looked at the inventory list and had us ship the good stuff to another facility).
In a word, yes! I believe that's exactly what's going on. Also, the string is closer to the magnets for half the cycle at the fundamental frequency and will be pulled more during that time. It's in the stronger field for less time at the higher frequencies, so it's not pulled as much out of tune for those harmonics. The lower frequencies are pulled sharp while the higher frequencies are still at pitch.
It's been quite a few years since I set all that up. I'll have to do it again sometime with a DAQ and Matlab so I can analyze the complete frequency spectrum of each note and the effect the magnetic field strength has on the spectrum. That sounds like work, though...
It doesn't just pull the string out of tune like turning the tuning peg does - it can pull the harmonics differently from each other so the overall tone can sound phased or strangely inharmonious (on guitars we used to call them "wolf tones" not sure if that term is still used these days) as the overtones aren't in tune with each other and you get a beating or phasing. It can be desirable if you like that sort of thing 
This explains why a note can sound in tune and out of tune simultaneously. I've always found that curious. Cool science, man! Thanks for the replies, I like to learn this stuff.
essentially any overtones that have part of an antinode close to the magnet will be pulled flat and will not sustain as long and any overtones where the node (the null) lines up over the magnet wouldn't be affected as much. At least that's the way I have always pictured it (though I always had the words node and antinode backwards until I looked it up just now:
Well, I'm just a civilian living on a much smaller boat in the same harbor. I went on the tour under the guise of "mueseum ship" and being an optics guy I spent a good bit of time on the big binos. Being among folks who are "in the know", several have told me she is really ready for duty in emergencies, and the lane victory is ready for logistics support. I have delusions of repowering her eventually,but that is another story entirely.
In my limited experience it does. I had a '78 P-bass, great player, great tone. I one day learned about adjusting the pickup a bit closer and so it matches the radius of the string orientation, noticed the pickup was dead parallel to the pickguard (the previous owner's doing, I suppose), adjusted it as suggested on the Fender website, and it gave it an immediate and obvious improvement in both tone and volume. I didn't expect that it would make such a big difference, so it was a pleasant surprise.
Which in turn, always means that you'll increase background noise level and 60 Hz hum. Period. I think it was Bartolini who made scientific measurements of how much output you loose, even if you adjusted the pickups in a fractional part of the strings actual gauge!
It's not only important to JUST change the pickup height, but you have to (really, if push comes to shove) change the pickup height accordingly to individual string gauge&height as well as string (neck) radius. A bit higher pickup height on the g-string side, and lowered at the E-string side. Tilted. Maybe. Some pickup manufacturers has staggered pole pieces, or ADJUSTABLE pole pieces just because of this, and if pickups has rails they're often radiused as well. Some guitar pickups for strats even has staggered pole pieces to accomodate for different in outputs between the different strings, say the wound ones, and the plain ones. IMHO you need different height for different strings, as they're varying by quite a noticeable degree.
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Especially, point 9. Where it says (among other things) :
"So, if you raise the string away from the pickup by 20% of its thickness you will lose half the signal. If it is a thin pickup, like our 5J jazz guitar pickup, it takes less than a little more than 1/16" to lose half the signal but still, approximately 20% of the pickup thickness. The above 4 examples are vastly different magnetic structures, but the way in which the magnetic field interacts with the string remains approximately the same on all pickups."
I find the big trade off, and which manufacturers has missed somewhat upon, is that some of them wow for radius, staggered, or adjustable pole pieces underneath the string, I think it's just important that these pole pieces runs exactly underneath the string and not to the side of the string. The magnetic field distance underneath the strings, is just as important as it is to the side of the strings. They are very rarely lined up like that anyway. They think it's crucially important with distance from pickup to string UNDERNEATH it but I think its just as important with output to the outer strings which the width are different from neck and bridge pickups. But this is pole pieces only. But even if you have rails, they can JUST be inside of the magnetic field and not tracking the outermost string, save for the neck pickup where the string spacing is narrower. I would love to if someone came up with the idea of a pickup with adjustable pole pieces... WIDTH!!! suck on that for a while...
Verdict, not only pickup height matters, but pickup height should - really - be different for each string. If you have pole pieces. Pickups with rails doesn't matters as much. The only way you can get by by it today, is to tilt the thinner string end slightly more upwards to the string and lower the pickup at the low e-string side. Which will end up in - maybe - a few trade offs in timbre/output/sound.
Which is one thing, why I like to have four screws in any pickup. The original Jazz bass pickups was brilliant with their four way screws even though it was single coil. Can't stand when it's not aligned up to the actual strings declining path towards the nut. You have to dabble with foam underneath and whatever. My biggest gripe was when Q-tuner started to make their new pickups (humbuckers) with two adjustment screws only. EMGs are kind of drag too in this regard. I e any pickup should be slanted a bit slightly towards the neck side. Like this (even if its for guitar in this particular case):
