Polepiece effects on tone

[Chill]

What characteristics of polepieces have what effects on tone? E.g.:
-longer/ shorter screws
-larger/ smaller diameter polepieces
-larger/ smaller screw head
-slugs vs screws

[hewo]

isn't the whole pickup suppose to determine the overall sound?
the view aperture is created in part by the pole pieces.
variation includes the curvature blade, knifelike thin, or thick like the melodymaker alnico blade without fingerboard radius of curvature.

the more focused the aperture, the more accurate the signal should resemble string vibration, and, i think it can tolerate higher string velocity speeds, meaning freqencies.

in the limit, if we downsize the polepiece to a diameter of zero, the sensing aperture becomes a point on the string. the signal would quantized at that limit, go-no-go, wouldn't it?

[Ruel]

I could be wrong but I think the size of the diameter of the pole pieces and the amount of magnetic material they contain would affect the overall characteristics of the tone of the pickup more than the length of the pole pieces.

[David Schwab]

I think there's so many variables, it's hard to make a definite correlation between each parameter and its effect... you change one aspect and it changes two...

For instance... pole pieces are both the conductor of the magnetic circuit and also the inductive core of the coil. So a fatter pole piece or blade is not only making a larger flux aperture around it, but also increasing the inductance.

Then you have the effect of counter emf, or eddy currents which form in metal parts on the pickups, including the poles. These currents produce their own magnetic fields that oppose the main field. This could cause a loss of highs... and maybe not. I think this is why some pickup makers use real thin blades, like the original Lawrence pickups. Bartolini used to make pickups with laminated steel blades, like that used in transformer cores to reduce eddy currents.

In Bill Bartolini's two patents he discusses the shapes of the pole pieces and how they sense the motion of the string. He says round poles get a plucky tone because they pickup the side to side and up and down motion equally. He had originally used flat, square, or parallelogram poles, and he claims they pick up more of the up and down motion, the way an acoustic guitar sound board works.

I see many attempts to focus the magnetic field in pickups... even Leo Fender added magnetic guides to his pickup designs after he left Fender... and of course Lace does the same thing. My thoughts are that any extra flux that's not sensing the strings is being wasted, so I would think having very high, wide fields don't add much to anything... but I haven't done any testing myself. I stop when I get a pickup design I like! :)

Then of course I'm sure different metals sound different too.

[hewo]

that was very informative. thanks for the explanations.

some improvements that technology has brought us would be reductions of inductances by materials, neodymium samarium cobalt & oxygen free copper.

i haven't seen any of these materials in pickups yet, maybe they are but unannounced.

the intent is to reduce inductance as well as irreversibilities, parasitic energy losses, e.g., the eddy currents previously discussed.

what i am wondering about is whether or not you physically need to have irreversibilities in order to have any signal at all. e.g., if we do not have impedance, then we can not have a signal generated.

[Chill]

Thanks for the info...I think someone is using neodymium in a pickup, but it's a non-standard design. Neo might also be good for an airbucker type design because it's field is so strong.

Say we have a PAF or a Duncan 59, what would the effect on tone be if we,

Change the polepieces to 1/2" screws instead of the 3/4" screws?

Use two slug coils?

Change the polepieces to wider diameter screws (with boring out the frames, etc...not something I'd do, but for the purposes of discussion)?

Change them to headless screws like set screws?

Change them to screws with heads larger than fillister heads?

[David Schwab]

that was very informative. thanks for the explanations.

some improvements that technology has brought us would be reductions of inductances by materials, neodymium samarium cobalt & oxygen free copper.

i haven't seen any of these materials in pickups yet, maybe they are but unannounced.

Fender has some pickups designed by Bill Lawrence that use samarium cobalt, as do the Q-Tuner pickups.

I've seen a few pickup makers using neo magnets, and they swear by them. I haven't tried them out myself yet.

the intent is to reduce inductance as well as irreversibilities, parasitic energy losses, e.g., the eddy currents previously discussed.

what i am wondering about is whether or not you physically need to have irreversibilities in order to have any signal at all. e.g., if we do not have impedance, then we can not have a signal generated.

You don't need to have a metal core in a pickup at all. Lawrence made air core pickups for acoustic guitars. Then you take Alembic for instance, they wind their pickups directly on ceramic magnets. Their pickups are just two pieces of copper clad printed circuit board with a ceramic magnet sandwiched between. They wind about 1500 tuns of 40 ga wire, and that's it! They are stacked pickups, with the bottom coil having a plastic core.

Of course they are low impedance pickups that require preamplification. Obviously Alembic pickups must have pretty low inductance.

I've seen some patents by DiMarzio where they are adding material to increase inductance... so I guess it's all about the tone you are going for!

As long as you have a coil and a magnet, you should get a signal.. the strength of the signal is another matter of course. Ribbon mics don't have coils, but instead a ribbon of copper or aluminum is hung in the field of a strong magnet. The ribbon has wires on each end. When sound makes the ribbon vibrate, it produces current. This ribbon is not magnetic, but still produces current because of the eddy currents produced.

The Lace Transsensor and Alumitone pickups also have no coil windings, except for a step-up transformer. I think the Villex pickups must work the same way, since he invented the Lace versions.

More ways to skin a cat? :D

I bet there's a lot of stuff yet undiscovered.

[hewo]

if the vacuum tube preamplifier input impedance is 1 megaohm, then we can settle basically our passive pickup performance specs. this excludes any intra preamplifiers or buffers.

based upon said amplifier's reception of the signal, wouldn't we specify the pickup as being equal to or less than 1 megaohm output impedance?

of course given that over the range of passive tone and volume impedance changes that realistically occur in the guitar, the pickup's impedance generally does color the guitar frequency spectrum. just like a speaker, it exhibits colorations. impedance is not constant over the spectrum.

analogously, the same can be said of inductance.

i think the trick is to at least generate enough frequencies. you can throw away what you already have, but you cannot throw away what you don't have. if you don't have highs, you can't throw them away. neither will your amp ever receive the highs. the same can be said of lows, although throwing them away passively requires tuned coils, inductors, which significantly add to parasitic losses.

this means the pickup designer and maker knows just about how much impedance and inductance that can coexist mutually to provide the spectrum of frequency generation. and part of that design making involves the thesis topic, polepieces. it appears that historically, the most sought after designs have not altered their specs, probably for darn good reasons. every part of the design in the pickup works. can we say it's optimized?

[ken]

A guitar's impedance is set more by the pots than the pickups, because you can
put higher value pots in the guitar, and as the pot value goes 'up', the guitar's tone gets brighter because of better impedance matching.

Ken

[hewo]

i tried switching from a half meg to a full meg, the difference was loudness and greater resolution for lighter volumes using the full meg. but the high pass bridge cap becomes invariantly sensitive in the lighter volume resolution regime. so i switched back to half meg. the sound thickens substantially for any pot value after exceeding a third of full scale.

[Luijo]

The reason why guitars sound brighter with bigger pots is not because of better Z matching. It is because there are less losses to ground with bigger pots than there are with smaller pots. Think of it this way, the signal has a harder job leaking to ground and an easier way to get to the amp when you have a path of very high resistance to ground than when you have a path of less resistance to ground. That's why some manufacturers offer a switch that allows you to bypass volume and tone controls altogether...less losses.
I read somewhere that's the reason why EVH just used a single volumen control in his guitars.
Impedance matching for audio porpuses is best when a very low Z signal (like the one at the output of buffered pedals) feeds a very high Z signal (like the input of an amp). Keep in mind that this not applies when we deal with power amplification, in which case you DO need to have equal impedances at both the source (amplifier) and the load (speaker).

[hewo]

think of the pot's wiper as the input signal fed to the vacuumtube preamp. when the wiper is zeroed the vacuumtube preamp's 1 megaohm input impedance is receiving a short to ground, zero impedance, by the wiper.

as we dial volume upwards, the preamp will be fed the combined impedance resultant of the pot's low side to ground, the pot's high side thru the coil impedance then to ground, including this same analogy for the tone pot if present. the tone pot high side usually is open ended, wiper is at same potential as preamp, and, the low side is high pass cap earthed.

as i earlier stated, for usual log taper, the 1st third range varies invariantly compared to the latter two thirds of range. this permits fine resolution control of soft volumes. i set the amp controls with capacity and merely dial the guitar in for needs.

comparing the full meg versus the half meg pot, if there's no high pass bridge cap for the volume pot, the incoming low frequencies entering the pot's high potential tab have a significantly easier time getting thru the carbon track and out to the wiper. the high frequencies will experince a significant attenuation before reaching the wiper tab. that's why the high pass cap is needed as a detour from high potential tab to the wiper tab. the reason why the low frequencies have the advantage of penetrating the carbon track is explained by visualizing low frequency, in the limit, as DC, not AC.

the tortuosity of carbon track passage is significantly greater for high frequencies as the pot's value is increased, the 1 meg versus 1/2 meg pot.
that is why the high pass cap detour route engages because it easily circumvents the normal tortuous path of carbon track. for higher value pots, the result is an over-sensitized high frequency route, and the resultant sound we hear appears over-brilliant.

by downgrading the pot's value, you are essentially allowing a proportional and favorable blended mixture of low frequency strength and high frequency strength, via two different routes to get to the wiper tab.

[David Schwab]

if the vacuum tube preamplifier input impedance is 1 megaohm, then we can settle basically our passive pickup performance specs. this excludes any intra preamplifiers or buffers.

based upon said amplifier's reception of the signal, wouldn't we specify the pickup as being equal to or less than 1 megaohm output impedance?

The input impedance and the output impedance are two separate things.

Input impedance is analogous to having a resistance across the input to ground, even if there isn't an actual resistor in the circuit. This resistance shunts part of the signal away to ground, thus diminishing the signal's strength.

Output impedance is analogous to having a resistance in series with the output of your device. This also diminishes the signal strength.

A pickup has an output impedance, which can be thought of as the DC resistance. In actual practice the impedance changes with frequency, generally getting higher with higher frequencies. But for now we will say our output impedance is 8,000 Ohms. This is a high impedance device.

So what happens when you take a high-Z pickup and connect it to a low-Z input? You are no longer getting all the signal from the pickup, but are picking up the signal from at the junction of two resistances, the output impedance of the pickup, and the input impedance of the amp. So in essence you have a voltage divider, just like a potentiometer. So for maximum transfer of signal, we want as high a resistance as possible between the signal and the ground (input impedance) and as low a resistance as possible between the signal and the amp (output impedance of the pickup).

So if the output impedance is higher than the input impedance, much of the signal will be shunted to ground. But if the input impedance is much higher than the output impedance, very little signal will be shunted to ground. If our output impedance is getting higher with higher frequencies, we will lose high frequency response. We can see that pickup with high DC resistance tend to lose highs.

Ideally the input impedance should be about 10 times that of the output impedance. So for an 8K pickup, you want at least 80K input impedance... except now we have things like cable capacitance creeping in, and the higher the output impedance, the more effect a small capacitance will have on the signal. And the higher the input impedance the more noise you pick up.


i think the trick is to at least generate enough frequencies. you can throw away what you already have, but you cannot throw away what you don't have. if you don't have highs, you can't throw them away. neither will your amp ever receive the highs. the same can be said of lows, although throwing them away passively requires tuned coils, inductors, which significantly add to parasitic losses.

This is where lower impedance pickups really shine. Or at the very least, by buffering the pickup with a very high input impedance device, like a FET, you retain the actual frequency range of the pickup more than with a totally passive system. This isn't always the tone guitar players are accustomed to however, but it works real well with bass.

[hewo]

agree, the fet or buffer can isolate the lickup from being loaded down. the sound gets too clean and clear for guitar.

but the vacuumtube essentially does the same as the fet, it buffers the incoming guitar signal from the downstream preamplifier stages.

so why the preference for having a vacuumtube instead of a fet for doing the same thing, buffering the pickup from downstream preamp stages that are not high impedance circuits?

or, can fet's be used to achieve the identical result of the vacuumtube? it must have something to do withthe coloration frequency response.

[ken]

FET's and tubes have the same very high input impedance, so they react 'almost' alike. Tubes are 'warmer' than FET's are because of interelectrode
capacitance effects, among other things. Each interelectrode capacitance drains off a tiny bit of treble, and if a tube has many parts, the effects add up.

Ken

[David Schwab]

I think the difference is that tubes are slower reacting then the transistors, and tend to round off the wave more.

[hewo]

i recall faintly mesa boogie had fet modules that substituted the preamp tube socket, can't imagine those days had high voltage fet headroom capability because that's what would be required. that would mean the differential between the gate to either source or drain would have to withstand quite a voltage potential.

is this still done today? if it is, does the fet still have to be replaced like a tube whose heaters eventually get cooler with use? it would surely revolutionize retubing hassles.

[ken]

The MB FET module never saw high volts, it had large I/O coupling capacitors to remove the DC volts from the AC signal voltage.

Peavey uses either a FET or silicon transistors with a biasing network from a germanium transistor to 'slow down' the signal response to mimic tubes in a Transtube amp.
I found out how they were doing this in a 1960's electronics textbook.

Ken

[hewo]

i don't know what peak to peak output ac voltage those mb fet modules generated, but surely it would still have to be in the realm of what a vacuumtube would have to push would'nt it?

speaking of the delay inherent to tube signal generation output, does this mean in real time there actually is a slight time shift between output versus input?

i originally thought there was no time shift between I/O, instead, the output had "extra" waves that weren't really intrinsic to the original input waveform.
i think i read somewhere that even order harmonics were characteristic of vacuumtube sound appeal. whereas, odd order harmonics characterized semiconductor coloration which do not appeal to human hearing. then later, i read on the web that even & odd order harmonics have nothing to do with the reason why vacuumtube generated output appeals to the ear. instead it was explained how the gain behavior, output versus input behaved, especially in the region of exceeding the confined voltage rails. i still do not fully understand why this is so because when i listen to the single coil free of any vacuumtube saturation distortion, it rings crystal clear, however, there is something different about it compared with a fet amp. it seems the strings are "sticky" sounding, as if alive beyond normal string vibration. the closest descriptive would be shimmering. could be this signature is a compilation of many components, including the speaker transformer & paper speaker too.

[Glass Snuff]

Regarding the role of the volume control in a guitar, it's primary contribution is to act as a 'load' on the pickup. The pickup is a coil and a magnet, and when a string moves in its magnetic field a voltage is induced across the leads. Of course, if the leads aren't connected, there's no circuit and nothing happens. If the leads are shorted together, there can't be a difference in voltage and again nothing happens. To get a useable output we need to put a resistor across the leads to act as a "load". The load allows some current to flow while keeping the voltage different (maintaining a potential differential, in more poetic geekspeak). This load is the volume pot. The greater the load, the greater the difference in potential, i.e, the higher the voltage will be. Thus, a higher value pot will produce more output from the pickup.

Now, since a pickup is a coil, it will have a resonance*, and the resonance will cause a peak in the output. In the case of a guitar pickup, this peak is above the fretboard frequencies (the 'fundamentals') in the area of the overtones. The size of the load (value of the volume pot) will determine the size of this peak, and a larger load** creates a greater peak. That's why a 1 Meg pot has more highs than a 250K.



* Forgive me for skipping a few pages of explanation here.
** Again, I'm taking a short-cut. Engineers would say a smaller value was a larger load, but that tends to confuse musicians. ;)

[NightWinder]

Well said!

[hewo]

but the need for, by user preference, for the volume pot hi-pass cap, e.g. 1000 pico, compensates for inadequate highs when the volume is turned down. does not this show that the highs aren't getting through the carbon track as easily to the wiper tab unless we allow for a hi-pass detour?

[David Schwab]

Regarding the role of the volume control in a guitar, it's primary contribution is to act as a 'load' on the pickup.

Just to be pedantic, the primary role of a volume control is to control the volume of the pickup. The pickup doesn't need a load, that's more of a byproduct of the potentiometer, and one could argue it has a somewhat undesirable effect of shunting high frequencies to ground.

The pickup is a coil and a magnet, and when a string moves in its magnetic field a voltage is induced across the leads. Of course, if the leads aren't connected, there's no circuit and nothing happens. If the leads are shorted together, there can't be a difference in voltage and again nothing happens.

That's not entirely true. If you wire up one coil as a closed loop, and have it close to another coil that is in the circuit, it will have an effect due to mutual inductance. The closed loop is in the magnetic field, so just as any conductor it will generate current, even if it's not going anywhere. The loop does have resistance, it's not a total short.

To get a useable output we need to put a resistor across the leads to act as a "load". The load allows some current to flow while keeping the voltage different (maintaining a potential differential, in more poetic geekspeak). This load is the volume pot. The greater the load, the greater the difference in potential, i.e, the higher the voltage will be. Thus, a higher value pot will produce more output from the pickup.

You don't need the load of the volume pot to get an output, and this can be demonstrated by the fact that you can wire the pickup directly to the output jack. The pickup will always be feeding a load as long as you have it plugged into am amp. The input impedance of the amp is analogous to a resistance between the input and ground, while the output impedance of the pickup is analogous to resistance in series with the pickup. The junction between these two resistances is your potential, and you can see where it looks just like a voltage divider or potentiometer (because it is). Ideally you want a high resistance as the input and a low resistance as the output.

The problem with a volume pot is as you turn the volume down you increase the resistance on the output of the pickup, and decrease the input resistance between the signal and ground, which changes the load, so to speak, and we loose highs.

Now, since a pickup is a coil, it will have a resonance*, and the resonance will cause a peak in the output. In the case of a guitar pickup, this peak is above the fretboard frequencies (the 'fundamentals') in the area of the overtones. The size of the load (value of the volume pot) will determine the size of this peak, and a larger load** creates a greater peak. That's why a 1 Meg pot has more highs than a 250K.

This all depends on the impedance of the pickup as well. An 800 Ohm pickup is not going to get loaded down too much by a 250K pot, and the resonant peak will be much higher than an 8,000 Ohm pickup. Also keep in mind that right after the resonant peak, the response of the pickup starts to drop off fairly rapidly. A larger load creates a lower peak... not sure how much larger the peak would be though, but on average it probably increases in amplitude as it gets lower, just based on the fact that the impedance decreases as the frequency does.

but the need for, by user preference, for the volume pot hi-pass cap, e.g. 1000 pico, compensates for inadequate highs when the volume is turned down. does not this show that the highs aren't getting through the carbon track as easily to the wiper tab unless we allow for a hi-pass detour?

No, it shows that the load on the pickup, i.e., the resistance between the pickup and ground, are shunting the high frequencies. Because the impedance increases with frequency, you can think of it that the highs are impeded more.

Put an active buffer between the pickup and pot, and you eliminate that whole scenario. :D

[NightWinder]

Schwab!!! Wuzzsup man! Breakin it down once again!! YEah!! LOL.
I have a super strat wired directly to the jack, no pots nada!! Sounds brutal and retains highs,,,, and the pickup is at 19.2k. I use this guitar for agressive showmanship and Haters........Floors them every time!!

[Glass Snuff]

I was trying to clarify some misconceptions. Your need to invoke transformers as pickups, no volume control at all, and 800 ohm windings (how did that work for you?) in order to reply says quite a bit about why I felt compelled to post in the first place. ;)

[David Schwab]

I was trying to clarify some misconceptions.

Oh I know you were... as was I. :D

Your need to invoke transformers as pickups, no volume control at all, and 800 ohm windings (how did that work for you?) in order to reply says quite a bit about why I felt compelled to post in the first place. ;)

Well I was pointing out that you really don't need a resistive load on the pickup to get a signal. You don't even need a coil... look at ribbon mics and Lace transsensor/alumitone pickups for examples. Pots will load the signal, and we all know that lower value pots will give a warmer tone.. depending on the DC resistance of the pickup. That and the tone control make a nice little LCR filter...

800 Ohm windings work fine. You will find similar winding in most low impedance microphones (probably much lower actually). Since we have standardized on high Z amps, you need to either use a transformer, like Les Paul did with the recording guitars, or a more modern approach and use a buffer amp, as you would find a company like Alembic doing.

In my case I did 500 Ohms on each half of a P bass pickup, and used a FET preamp to boost the signal up to hi-z levels. You get very wide and flat frequency response. Real smooth and warm sounding.

My current bass pickup designs use a bit more turns, but not that much. ;)

[hewo]

okay i get the treble leakage picture.
whatever highs that make it to the wiper rather go to ground at the zero volume position ground tab than go to the amp's hi impedance input. it's an easier path.

[hewo]

another question:
can i freehand machine a hole in my nightwatch just by using a dremel carbide cutter and maybe a reamer to mount switchcraft's wde13?
it's the jack that looks like a very long threaded bushing.
the nightwatch has a horrible factory jack located topside.
it makes the cord point outwards, imparting undue strain on the conductors.
if anybody knows how to do this without risking trouble please respond. the nightwatch is mint mint.

[David Schwab]

Why not get a 90° angled cord?

[Glass Snuff]

Well I was pointing out that you really don't need a resistive load on the pickup to get a signal.
You don't think an amp qualifies as a load?

800 Ohm windings work fine.
If they "worked fine", you wouldn't need a preamp.

I understand, you're suffering from the "big fish in a little pond" syndrome. You're used to wowing your customers with your techno-babble, but I'm not one of your customers. At this point you have so little credibility, I wouldn't even accept an apology.

[hewo]

the amp is an infinitesimal load because of the impedance miss match, you can throw lows into high impedance, not vice versa.

so when you say amp is a load, yes, infinitesmally.

the 800 ohm coil impedance sounds not to standard, it must be a new venture that not too many folks adapt into. how do you generate bass with only 800 ohms impedance? sounds like the opposing spectrum of the barcus berry hotdots that required specialized electronics interface for the amp.

[David Schwab]

You don't think an amp qualifies as a load?

For crying out loud.... :rolleyes:

I said:
You don't need the load of the volume pot to get an output, and this can be demonstrated by the fact that you can wire the pickup directly to the output jack. The pickup will always be feeding a load as long as you have it plugged into an amp.

You were talking about the pickup needing the volume pot as a load to produce a signal. That's incorrect. I said you don't need a volume pot... the amp was a load. Go back and read it again.

You said:

To get a useable output we need to put a resistor across the leads to act as a "load".

Come on, that's just wrong. There's lots of input stages that don't have a resistor to ground... FET's and op amps can have pretty much infinite input impedance. A unity gain buffer (voltage follower) made from an op amp doesn't need, or even have, a resistor at the front end. It draws no current from the source and presents no load.

Also... if you don't plug the pickup into anything, what difference does it make as to whether or not it's producing a signal? That's like the old question "if a tree falls in the woods and there's no one to hear it, does it make a sound?"

My personal opinion is I don't want my instrument to sound different depending on what front end it's plugged into. So I like to keep the pickups isolated from the amp, and that's what you achieve with a buffer.

If they "worked fine", you wouldn't need a preamp.

That's your opinion. What works well for one person is another person's crap. Do you not understand the concept of low impedance pickups? They work better than high impedance pickups if you are looking for a wide and flat frequency response, and you aren't going to get that with a lot of windings. I guess there's a lot of active pickups on the market because they don't work well, right? Also as I mentioned low impedance microphones work even though they are about 100 Ohms. I don't need a preamp if I plug into a low impedance input, like a mixer. But as I said we have standardized on high-z gear. Les Paul also wound low impedance pickups for his personal guitars.

I understand, you're suffering from the "big fish in a little pond" syndrome. You're used to wowing your customers with your techno-babble, but I'm not one of your customers. At this point you have so little credibility, I wouldn't even accept an apology.

Excuse me? I have no clue what you're talking about or even why I would need to apologize to you. I'm not suffering from anything at all. You don't know me, so that statement is invalid.

Credibility? Let's look at that word... "the quality of being trusted and believed in." I have instruments and pickups I designed and made that anyone can look at and listen to. So if I say I build basses and pickups and they play and sound great (subjective of course...) I can back that up. That makes me credible. That's known as integrity. Talk is cheap. What do you do? Have something to show us?

I don't make a living doing this stuff anymore, so I really don't care. I'm not trying to prove anything at all. But I've been doing it for a long time and know a thing or two, as do others here, and I'm only here to share what I know and help people out if they need it. Why are you here? To make yourself look good?

This is a public forum for discussions about pickups and such, and you came here with the attitude that you were teaching the pickup makers something we don't know. You can voice your opinion on anything, and I can agree or disagree if I choose. I was pointing out that some of your post wasn't quite correct.

...but that tends to confuse musicians.

You apparently wanted to come off like some expert and don't like being corrected.

I don't need to "wow" anyone with anything. I was stating facts, not conjecture. I build and play basses and guitars and make pickups and electronics for them in my spare time. I have customers I have had for the past 20 years because they like my work. If someone is interested in what I'm doing it's because they like what they hear and see, and has nothing to do with "techno babble" ... I'm using the same "techno babble" that you might find someone like Rick Turner using by the way ... but I guess you know more than he does right? Actually you were spewing a lot of "techno babble" yourself, were you not?

Do you even know who Rick Turner is? He's the guy who pretty much invented "active" pickups and boutique basses by winding 1500 turns of 40GA wire around a magnet and then used a preamp to bring it back up to line level. And not only do these pickups "work fine" they are well known for the clear tone and sell on very expensive Alembic basses.

Maybe I can come off a bit brusque or blunt, but to tell you the truth there's so many "internet experts" on these forums that say such crazy things (like active pickups are active because they use electro-magnets!) that I find myself getting impatient. I'm a friendly person and the internet does not convey such things easily. But I didn't even say anything to you to warrant you getting yourself worked up over.

I'm not here looking for acceptance and don't need to have any credibility. I'm not trying to prove anything, but I like giving people info if that helps. I don't pretend to know everything, but I know what I know, and the more I learn the less I know! But we can learn something new everyday. You have to be open to it however. :D

[Just Bob]

For crying out loud.... :rolleyes:



Well, you have to admit the guy has a pretty nice picture of a tube next to his name. That must count for something. And, despite his apparent lack of expertise, he does make up for it with his depth of conviction. If people had to be right, we wouldn't have politicians and where would we be then??

[David Schwab]

Well, you have to admit the guy has a pretty nice picture of a tube next to his name. That must count for something. And, despite his apparent lack of expertise, he does make up for it with his depth of conviction. If people had to be right, we wouldn't have politicians and where would we be then??

It's a nice picture of a tube too. :) Maybe I need to smile in my picture...

Hey, I'm just wondering why he got so bent out of shape in the first place...

OK.. back to winding 1000 Ohm pickups.... ;)

[Glass Snuff]

I was trying to simplify things in an attempt to explain something. It seems to me the fact that your "pedantic" reply wasn't well received should not be confusing, but then again, if you possessed that level of understanding you wouldn't have posted in the first place.

Sorry to hear you're no longer making basses. However, that should in no way impune your expertise. :rolleyes:

Yes, I'm a newbie here, but I've been around the internet since before there was a WWW, which means long before there were forums such as this. I can, I think, reliably predict people's reactions to me. A few will be thankful for my input and seek my help, but most of you will think I'm an asshole. :cool:

[David Schwab]

I was trying to simplify things in an attempt to explain something. It seems to me the fact that your "pedantic" reply wasn't well received should not be confusing, but then again, if you possessed that level of understanding you wouldn't have posted in the first place.

Who was it not well received by besides yourself? I was also trying to clarify some thing that maybe some people don't understand well. NightWinder was busting my chops, but I guess the last time I went on a rant gave me a bad rep! :eek: :p

Sorry to hear you're no longer making basses. However, that should in no way impune your expertise. :rolleyes:

I didn't say I'm no longer involved in lutherie, I said I don't make a living at it anymore. I have a "regular" day job, like some other people here do, and I do lutherie on the side. I have a family to support, and making guitars and pickups doesn't always pay the bills. Neither does playing music, but I do that too. In the end they all contribute to an income, but I meant making basses, et al, is not my sole livelihood. I actually just started my business back up after a long hiatus... so If I start to do more basses than graphics, then that statement will change.

Yes, I'm a newbie here, but I've been around the internet since before there was a WWW, which means long before there were forums such as this. I can, I think, reliably predict people's reactions to me. A few will be thankful for my input and seek my help, but most of you will think I'm an asshole. :cool:

I wasn't trying to start anything with you, and I didn't insult you or say you don't know anything. I was just correcting a couple of points that were probably due to you simplifying things, which is fine. I was trying to contribute to your info, not dis you. A volume pot can be one persons tone shaping bliss and another person's mud maker. All depends on what your after. ;) What I'm doing is probably very different from what other's are doing here pickup wise. But we can all find bits of info that can help us from time to time.

We are all assholes here from time to time... it's the nature of creative people! :D

[Glass Snuff]

Well said, Dave. Not sure exactly what tipped the scales, but suddenly I feel like I've been baiting you, and I apologise for that.

[David Schwab]

Thank you. :D

Back to talking about wires....

[Steve Conner]

You guys all forgot about the most important factor in pickup tone! :D The resonance between the inductance of the pickup and the capacitance of the guitar cord (plus any caps in your tone pot) creates a 2-pole low-pass filter with a resonant peak. The size and location of the peak depends on how hot the pickup is wound, and how long your guitar cord is, as well as its capacitance per foot. It also depends on your volume and tone pot settings in a complicated way.

Cranking the tone control to minimum tends to lower the frequency of the resonance drastically and make the peak bigger. With really hot wound pickups it can honk almost like a parked wah-wah. These hot pickups will probably have the peak in the midrange even with both knobs up full.

The volume pot damps the resonance, both by its resistance to ground at full volume, and by its isolating the pickup from the cable capacitance at part volume. A bright cap lessens the damping. The input impedance of the amp damps it too.

I guess that's why folks like active pickups, because they want their instrument to sound the same no matter whether they use a 10 foot cord or a 50 foot one. An active buffer built into the guitar can present a very low load capacitance, and presumably give the hottest humbucker a bright top end. (unless self capacitance of the coils limits it)

I never got the point of active pickups on bass, unless it's to sneak some extra EQ past sound guys who insist on taking a DI from the input of your amp. ;-)

IMO. YMMV.

[Glass Snuff]

Really, I think one of the Moderators should split this thread off at post #7 and title it "The effects of pots, etc," or something. We haven't mentioned polepieces in a long time. :eek:

(and then delete THIS post, which will no longer make sense)

[David Schwab]

I never got the point of active pickups on bass, unless it's to sneak some extra EQ past sound guys who insist on taking a DI from the input of your amp. ;-)

Here's my take on the subject.

I think there's two schools when it comes to bass players. One is the hi-tech bunch, started by Alembic, and its many followers (that would include me) and the other would be the vintage bunch.

The hi-tech bunch want ultra hi-fi pickups and electronics, and generally use a wide range tone with extended top end.

The vintage bunch like old school tone and often use flat wounds and tube amps.

So if you look at the time line... back when the P-Bass was king (mis 70's), DiMarzio came out with the Model P, which gave more highs and output. The next step in that evolution was Hi-A pickups and then the EMG-P. These were all designed to give a wider range tone from the bass.

Back when I started playing, most people played a P-Bass... I played a Rick... I grew up with, and love the Motown bass tone, but I was looking for a very modern bright tone... so I was always tinkering with my basses.

Being that bass amps pretty much sucked up until fairly recently, a lot of bass players were always looking for more accurate sound, and went so far as using things like Crown power amps and a custom hi-fi speaker setup.

I think a lot of bass players are fascinated with hi-tech gear, because bass players always had less choices... we get the corner in the music store, and the back of the catalogs! Fewer choices of amps, strings, pickups, etc. That's changed over the years of course, but I still see that fascination with things like 11+ string basses and on board electronics. And you can see that guitar players seems to be more into vintage styled gear, while basses tend to look more "futuristic." Look how many more headless Steinberger basses you saw compared to guitars back in the 80's.

So the way I got into making pickups was I was building basses, and decided to use EMG's, since I had been using them in my Ibanez 5 string. I started not liking the tone of the EMG's because they sound too processed.. they seem to have their own EQ curve and sound compressed. I wanted the most transparent sound, so I started trying different pickup designs.

It's very different from what you expect from guitar pickups... in a guitar you want that interaction and resonant peaks. In a bass you want a more clear smooth tone ... less peaky. I figure if you start with more frequencies and a clean tone, you can dirty it up later.

For me, when I'm playing something like a Fender bass, I'm always trying to get more tone out of it.

I use very little EQ at my amp, and some times I plug directly into the PA. Lately I've been bypassing the preamp on my amp entirely and plugging into the effect return. :D

[Steve Conner]

Hi David, that's very interesting! I started out as a guitarist, but my only experience with gigging is on bass. (I wanted into the band bad enough that I offered to play bass to get the gig.) I always liked listening to funk and Motown stuff, so my tone of choice would be to fart through an underpowered tube amp and 2x15" cab. I like how a tube amp adds a bit of grind and excitement when you play harder.

Having said that, with the kinds of gigs we play, I usually end up going through someone else's bass rig anyway. :( And, I'm also a big Stanley Clarke fan, but I know he belongs to the Alembic school, so go figure.

The bass I use is the old budget model Peavey Cirrus with passive electronics and two pickups of goodness knows what kind. They just look like plastic oblongs with no visible pole pieces, and I never did figure out how they worked. (Having read this thread, I guess now they might just be a coil wound round a bar magnet.) I'd love to try the big-ass humbucker that comes fitted to the Music Man Stingray, but it'd never fit without serious routing.

I tinkered with a few things, like wiring the pickups in series, but the output got way too hot and made the front end distort on every amp I tried it with. In the end I wired it like a guitar, with a 3-way LP style pickup selector switch and a single volume and tone.

The hi-techest bass I ever owned was a Hohner 5-string with the Steinberger headless system. I wired it so I could switch between active and passive in case the battery ran out, so I got to compare the effect of the active circuitry. The only thing that really stood out to me was the treble boost that gave more of a piano-type sound on high notes instead of a monkey hoot.

In a vain attempt to stay on topic (maybe a mod should split us?) did anyone see the Duncan Parallel Distortion humbucker? Each pole piece is two rectangular prongs made of thick sheet steel. I've no idea what that's supposed to do.

[David Schwab]

Hi David, that's very interesting! I started out as a guitarist, but my only experience with gigging is on bass. (I wanted into the band bad enough that I offered to play bass to get the gig.) I always liked listening to funk and Motown stuff, so my tone of choice would be to fart through an underpowered tube amp and 2x15" cab. I like how a tube amp adds a bit of grind and excitement when you play harder.

I like that tone too, but I don't want that to be my only tone I get. I'm a big Jack Bruce fan... He was pivotal in how I play bass. My first big bass amp was a Peavey "Bass" ... their first model. It had a wonderful distortion feature that nailed that Jack Bruce/Felix Pappalardi/Tim Bogert tone, and that's why I bought it.

These days I use an old Blue Tube pedal that has a 12AX7 in it when I want some grind. I think it was from having too many under powered amps over the years that makes me crave clean headroom! I have a Mesa 400+ rig that I stopped using because it would get too crunchy when I dug in. Maybe I just play too loud? :p My first real bass amp was an Ampeg B-15n... lovely sounding amp, but totally unsuitable for gigging with a drummer! I stay away from tube amps these days, they just feel and sound too mushy. Great for guitar though. :D

Having said that, with the kinds of gigs we play, I usually end up going through someone else's bass rig anyway. :( And, I'm also a big Stanley Clarke fan, but I know he belongs to the Alembic school, so go figure.

I'm a big Stanley fan too. It was trying to get that Alembic tone that drove me to mod my 1972 RIC 4001 bass to death, and later what made me decide to build my own bass... I just wasn't finding what I wanted--that I could afford-- in commercial basses. Same holds true for pickups.

The bass I use is the old budget model Peavey Cirrus with passive electronics and two pickups of goodness knows what kind. They just look like plastic oblongs with no visible pole pieces, and I never did figure out how they worked. (Having read this thread, I guess now they might just be a coil wound round a bar magnet.) I'd love to try the big-ass humbucker that comes fitted to the Music Man Stingray, but it'd never fit without serious routing.

Jeff Berlin played a Peavey Palladium for a while. I'm not familiar with either bass, but he got a great tone out of that bass. There's might be poles under the cover... it's hard to say what's inside a closed cover pickup. Look at EMG.. inside their soap bar pickups they have stacked Jazz pickups, split P pickups, and standard humbuckers. The Peavey might use steel blade poles... I don't think too many pickup makers wind right on the magnet.

I tinkered with a few things, like wiring the pickups in series, but the output got way too hot and made the front end distort on every amp I tried it with. In the end I wired it like a guitar, with a 3-way LP style pickup selector switch and a single volume and tone.

One of the easiest ways to get more tones is to add a preamp. I have a stacked bass/treble setup, and I'm always changing my settings from song to song, along with mixing my two pickups. I think having two volumes is better than a switch on a bass.

The hi-techest bass I ever owned was a Hohner 5-string with the Steinberger headless system. I wired it so I could switch between active and passive in case the battery ran out, so I got to compare the effect of the active circuitry. The only thing that really stood out to me was the treble boost that gave more of a piano-type sound on high notes instead of a monkey hoot.

If all depends on the pickups and the preamp. It souldn't really alter the tone that much when the tone controls are set flat, besides what effect buffering the pickups has.

In a vain attempt to stay on topic (maybe a mod should split us?) did anyone see the Duncan Parallel Distortion humbucker? Each pole piece is two rectangular prongs made of thick sheet steel. I've no idea what that's supposed to do.

It's the same concept as a Fender bass pickup. Fender first had a single pole under each string, and the attack of the string sometimes made the amps at the time break up. So they switched to two magnets on either side as a way to soften the attack.

I remember reading that Duncan did this for tremolo users, and I think it was so when you do a dive bomb, the string wont smack right on top of the pole. Also the string hight is changing as you press your bar in, so I supposed this was to try and even that out.