Balanced Guitar Pickups

[MikeRivers]

I've been playing with some Focusrite computer audio I/O boxes lately and have found, a bit to my surprise, that the DI input jacks (line inputs switched to DI mode, not independent jacks) are not only high impedance as expected, but they're differential (balanced).

 

So this got me thinking. Since a lot of pickups these days are constructed with the two ends of the winding coming out through two conductors of a shielded cable, and one side only gets grounded to the shield at the guitar's output jack. If you replaced that jack with a TRS jack, connected the two ends of the pickup winding to the tip and ring of the jack, and the shield of the pickup cable to the sleeve, you'd have a balanced connection if you connected it to a balanced input with a TRS cable. You'd also have an unbalanced (conventional) input if you connected it with a standard TS guitar cable.

 

I suspect that most noise is picked up by the pickup rather than the cable, but if that cable does tend to act as an antenna, the balanced output and differential input would improve the common mode noise rejection.

 

Now, this isn't a construction project yet, but food for thought for those of you who customize the wiring in your guitars. There are obvious considerations about how to deal with pickup switching and controls that need to be dealt with. As a thought exercise, though - a single pickup wired straight to the jack - it seems like a pretty good idea.

 

I remember back when dinosaurs roamed the earth reading an article about Chet Atkins in which he said he made low impedance pickups for his guitar to get lower noise and less high end loss, but he didn't say specifically that they were balanced or what he was connecting it to. Gibson made a Les Paul Recording model which indeed had low impedance balanced-wired pickups with an XLR connector at the output, and a special amplifier to go along with it. So the idea isn't new, it just, I guess, never really caught on.

[WRGKMC]

I'd think you would know that low impediance is 600 ohms.

This boost the voltage and lowers the current for long transmission distances. (like they do with AC transmission lines)

This preserves the frequency responce and signal quality.

Its converted back to high impediance at amp.

 

You would NOT get low impediance just sticking a TRS jack in the guitar with any wiring combination.

Nor will it reduce any noise associated with guitar pickups other than the cable might be better quality.

Guitar pickups are high impediance. Even the weakest coils are above 3K ohms.

 

If you want a low impediance guitar install high to low impediance transformers in the guitar like thay do with the Les Paul Recording guitar.

It will be good for clean tones recording direct. http://www.flatearthguitars.com/files/LP_Recording_71_77-Sig_Guitar_Bass.jpg

[WRGKMC]

What you can do thats really cool is use a TRS jack and run stereo pickups like a rickenbacker.

Record each pickup to a separate track and blend the two pickups after they are recorded.

You can even have different effects on each plus sone actual stereo separation due to the string vibrating

differently over each pickup. Its like putting your ears between the two pickups.

[UstadKhanAli]

I've heard about that but never done it, but it sounds like it could be really cool.

[JeffLearman]

There's less difference between balanced and unbalanced than we often tend to think. For either balanced or unbalanced, the signal is the difference between two pins. For unbalanced, one just happens to be grounded. The coils on the guitar will "pull" on the ground lead as it "pushes" on the hot lead.

 

When connecting two pieces of AC-powered gear, the difference is more significant due to the signal ground being connected to the power ground; neither end expects the other end to be jerking power ground around at audio frequency rates. (To the extent one does, we get ground loop hum.) But a guitar is passive and it's floating. (The floating part is more important than the passive part.)

 

Yeah, I know I'm oversimplifying.

[MikeRivers]

 

I'd think you would know that low impediance is 600 ohms.

 

 

Uh . . . why so arbitrary. Yes, I'd consider 600 ohms to be "low impedance."

 

 

This boost the voltage and lowers the current for long transmission distances. (like they do with AC transmission lines) This preserves the frequency responce and signal quality. Its converted back to high impediance at amp.

 

 

Um . . relevance? AC transmission lines don't care about impedance, they do, however, run long lines at high voltage to reduce the current so they can use smaller wire (but bigger insulators). This really has nothing to do with small signal transmission (like from a guitar to an amplifier) because there's virtually no power involved.

 

 

You would NOT get low impediance just sticking a TRS jack in the guitar with any wiring combination.

 

 

Of course not. You'd get the pickup's impedance. But you could get it on a balanced line. Are thinking that low impedance is balanced and high impedance is not? That's absolutely incorrect.

 

 

Nor will it reduce any noise associated with guitar pickups other than the cable might be better quality.

 

 

No, it won't reduce noise picked up by the pickups themselves. But it could reduce noise picked up by the cable. That was my point.

 

If you want a low impediance guitar install high to low impediance transformers in the guitar like thay do with the Les Paul Recording guitar.

 

 

Yes, you're definitely confused about the non-relationship between impedance and balanced connections. Get thee to my web site and start reading the technical articles.

[MikeRivers]

 

What you can do thats really cool is use a TRS jack and run stereo pickups like a rickenbacker. Record each pickup to a separate track and blend the two pickups after they are recorded.

 

 

Isn't that how stereo wired guitars are usually arranged? Sure, it uses a TRS jack, but not for the purpose that I proposed.

[MikeRivers]

 

There's less difference between balanced and unbalanced than we often tend to think. For either balanced or unbalanced, the signal is the difference between two pins. For unbalanced, one just happens to be grounded. The coils on the guitar will "pull" on the ground lead as it "pushes" on the hot lead.

 

 

That's the general case, and almost always the case if you're talking about guitar amplifiers, but I was talking about the instrument input on a specific models of computer audio interface from a particular manufacturer. These is a differential input. The output of the preamp stage is the difference between the tip and ring signal, just like a mic preamp is the output of the difference between pins 2 and 3.

 

If the pickup is wired so that the two pickup leads go to the two inputs of the differential amplifier, you'll get the pickup output amplified just as you expect. One side goes positive with respect to ground, the other side simultaneously goes negative. But suppose you have some noise that's picked up by the cable. Both conductors, since they're close together, will pick up the same noise, at the same amplitude, and the polarity of the noise on both cables will be the same. Let's say you have 1 volt of noise on each cable. Those go into the differential input (along with the desired pickup signal). It does it's thing, 1v - 1v = 0v. Goodbye, noise.

 

Now that's only half the job, though. We refer to inputs like mic preamps as "balanced" but really, outputs are balanced (or not). Inputs are differential (or not). Balanced means only that the source impedance of both legs is identical. It says nothing about the number of ohms except that it has to be the same on both legs. It says nothing about the voltage. One can be zero volts. This is what's called "impedance balanced" or more accurately, "single ended balanced."

 

Equal source impedances as well as equal load impedances will insure that a current induced in both cables will have the same voltage at the inputs of the differential amplifier,

 

 

When connecting two pieces of AC-powered gear, the difference is more significant due to the signal ground being connected to the power ground; neither end expects the other end to be jerking power ground around at audio frequency rates. (To the extent one does, we get ground loop hum.)

 

 

Congratulations! You've just recognized The Pin 1 Problem.

 

 

But a guitar is passive and it's floating. (The floating part is more important than the passive part.)

 

 

But ground problems aren't the only source of hum.

[TieDyedDevil]

Running a balanced hi-Z (or even guitar-Z ;-) ) line won't do a thing for inductive coupling (hum due to EM fields inducing a voltage in the coil(s) of the PU).

 

However, if you had a shielded humbucker PU with excellent balance between the coils, a shield connection running back to the preamp, and a floating differential feed to a differential input... you just *might* notice a slight reduction in any noise that may otherwise have been picked up by a single-ended connection. Of course, a shielded cable with 100% shield coverage might give you the same benefit without all the "non-standard" circuitry.

 

Honestly, the best thing you can do if hum pickup at the guitar is a problem would be to install shielded active pickups. A friend who plays a Tele used to have horrible problems playing at one particular bar. He replaced the PUs with a drop-in EMG set and his Tele had no more hum at that bar.

[WRGKMC]

I think the passive volume controls in a guitar are going to pose a problem for you.

They would cause an imbalance wired as is and you would have to shield the guitar cavity

independantly. The normal signal to ground method of using pots wornt work.

 

The other item is guitars pickup requires instrument level to sound right.

I have no idea what model the Focusrite, there are many. But it sounds to me like the input is either low impediance or line level balanced,

neither which is correct for a guitar pickups signal strength straight in.

 

I'm guessing its a balanced line level input designed to connect a balanced preamp output.

If thats the case, preamping the pickup signal for a line level input or converting the

signal to low impedance fro a mic level input is needed.

 

In any case, I record direct all the time and have no hum issues and I even still use an older CRT monitor in the studio.

All my single coil guitars either have the cavities grounded with copper foil or had the single conductors wires to the pickups

replaced with shielded wire. Having shielded/grounded covers helps too.

[MikeRivers]

 

I think the passive volume controls in a guitar are going to pose a problem for you.

 

 

I did stipulate that volume controls and switches (as originally wired) may be a problem. My suggestion as an experiment is to simply choose one pickup, wire it up as a balanced connection, and see what it does for you. It's possible to rebuild the whole inside of the guitar to be balanced if one wanted to do so.

 

 

you would have to shield the guitar cavity independantly.

 

 

Now this is exactly where the balanced wiring would help if it was done correctly. I've run microphones through zip cord and no shielding without hum problems.

 

 

The other item is guitars pickup requires instrument level to sound right. I have no idea what model the Focusrite, there are many. But it sounds to me like the input is either low impediance or line level balanced,

 

 

Nope, this is a real DI input, suitable level for an instrument, 1 megohm between tip and ring, or 500K when connecting "unbalanced." It's a Focusrite Scarlett series, and the Saffire Liquid 56 which I recently reviewed has the same DI input setup. These guys aren't ignorant.

 

 

In any case, I record direct all the time and have no hum issues and I even still use an older CRT monitor in the studio.

 

 

Hey, if you don't want to play, you don't have to play. But don't rain on my parade. I think the idea has potential, but I'm an engineer, not an electric guitarist. My guitars usually hum when I plug them into DIs in the studio unless I face the right direction to null it out. This is hum picked up by the pickups, not the cables, so it's a different problem. But the cable is a potential problem and this, if they built guitars right, is a potential solution.

[Hard Truth]

I have often wondered why guitars haven't gone low impedance so that direct boxes and separate instrument inputs would be unnecessary, and the ability to run longer cables added. The posts above show some of the challenges. What are the issues at the amp end? Can existing classic amp designs be easily modified for low Z without changing the characteristic sound? Would the guitar signal sound different if it has to go through two transformers or equivalent active circuits (one at each end)?

[MikeRivers]

 

I have often wondered why guitars haven't gone low impedance so that direct boxes and separate instrument inputs would be unnecessary, and the ability to run longer cables added. The posts above show some of the challenges.

 

 

Those aren't challenges, those are excuses for . . well, I don't know what other than not doing it. The best argument against the balanced pickup wiring is that there's so much more hum being picked up by the pickups than the by the cable that it might not be worth it.

 

Understand that wiring the pickups doesn't make them low impedance. They're still as high impedance as ever, and still need a high impedance input in order to sound like they're supposed to sound.

 

The way to make a low impedance pickup is to use less wire. This has a lot of advantages - lower inductance, lower capacitance, and lower resistance. But the disadvantage is that a smaller coil of wire makes a poorer generator and the output would be very low. Probably on the order of . . . well, a dynamic microphone.

 

 

What are the issues at the amp end? Can existing classic amp designs be easily modified for low Z without changing the characteristic sound?

 

 

I don't see why not. Any decent mic preamp design should work fine. That would boost the signal from the pickup to essentially "instrument" level, and then you could overdrive the first stage of the amplifier, or the output stage, or anything else in between just like you normally do.

 

It would take some work to design a low impedance pickup that sounds as good as those that they've been making for 75 years, but there are contemporary pickup designers who I'm sure would be up to the task as long as someone could create the market that would justify the development.

 

One of the things that a designer would need to accommodate is how the load affects the magnetic circuit which affects the string mechanics. There's also something to how the source impedance affects some guitar amplifiers. There's a Milennia Media box that can be a DI or re-amp box. John found that he needed to offer a couple of different selections of output impedance (simulating the output of a guitar) when re-amping with it since this made a difference in how the amplifier sounded. I can't explain that one, but I won't argue with John's ears. He's a guitar player.

 

The reason, I suspect, why they make guitars and amplifiers the way they do is because they've always done it that way. If you had a low impedance guitar, you might find yourself in a place where you didn't have an amplifier to plug it into if you didn't have your own.

 

 

Would the guitar signal sound different if it has to go through two transformers or equivalent active circuits (one at each end)?

 

 

The low impedance design doesn't need transformers, unless you wanted to use a transformer at the input of the (pre)amplifier for the coloration. If you had a low impedance guitar and wanted to plug it into a conventional amplifier, then you'd need a transformer or an outboard preamp, and that would most likely change the sound.

[WRGKMC]

Mike you dont have to be a condecending ass. I have degrees in electronics too. I've also been employed by major

manufacturers hald a lifetime, woop de do. Main thing is I do have a good 40 years practical experience in

music electronics. I'd be surprised if there isnt anything I havent tried or experemented first hand "but" I do keep an open mind.

 

I cant say for sure weather your idea would work because I dont have the schematics to analize.

All I could find is the specs like this. They seem to be the same for those models

Analogue Channel Inputs (Inputs 1-8)

 

[roomjello]

I'm reading this thread leaning some cool stuff, but

 

Mike you dont have to be a condecending ass.

 

[onelife]

Do you need to have a centre tap for a balanced line?

[onelife]

I have often wondered why guitars haven't gone low impedance so that direct boxes and separate instrument inputs would be unnecessary...

 

what about these guitars?

 

 

 

I don't believe they had batteries in them

[MikeRivers]

 

Mike you dont have to be a condecending ass. I have degrees in electronics too. I've also been employed by major manufacturers hald a lifetime, woop de do.

 

 

Whoop de doo indeed. I have a few years on you but that doesn't mean that I know any more than you do. You posted arguments based on I don't know what . . . ASSumptions? I only threw out something that might be a good idea, based on testing a unit that could accommodate it.

 

 

Main thing is I do have a good 40 years practical experience in music electronics. I'd be surprised if there isnt anything I havent tried or experemented first hand "but" I do keep an open mind.

 

 

Have you ever tried balanced wiring between a guitar and amplifier?

 

 

I cant say for sure weather your idea would work because I dont have the schematics to analize. All I could find is the specs like this. They seem to be the same for those models Analogue Channel Inputs (Inputs 1-8)

[MikeRivers]

 

Do you need to have a centre tap for a balanced line?

 

 

No. You only need both ends of the pickup winding. Electrically, you don't even need the shield. It carries no current in a balanced connection, but it helps keep the stuff that a differential input cancels away so it doesn't have to work so hard.

[MikeRivers]

 

what about these guitars? I don't believe they had batteries in them

 

 

Who needs batteries? I recognize the Les Paul Recording, but what's the other one? Is that one of those stereo-wired ES-335s? If so, it probably has a TRS jack, but that's not balanced, it's one pickup on one lead and the other pickup on the other lead.

 

But while I'm on a roll with great ideas about electric guitars that you guys can argue with me about, how about this: Connect the pickups directly to the jack (bypassing all the guitar controls) and run them into two independent channels of a purpose-built amplifier. You'd have no volume and tone controls hanging across the pickups, you'd do all of that in the amplifier itself. It wouldn't be too difficult to remote-control the amplifier's channel volume and tone controls from the guitar.

[WRGKMC]

 

I'm not trying to sell a product here, just discuss a concept. I don't have guitars here that I can rewire. I do have the facilities to test it, however, if you want to modify one and send it to me.

 

 

I have over 30 guitars here I built by hand and wired for every configuration possible. I dont plan on giving any of those up but I have an extra body and neck here and enough spare parts if you want to tinker it back together. You would have to cut your own pickguard but you wouldnt even need that for testing pirposes, just scre the pickup into the open route and string it up.

 

I'll throw in a multi conductor humbucker with 4 conductors and a separate ground you can use to test with. I probibly have an extra 20 sets in my parts cab.

You can wire the pickup any way you want, single parallel, or HB. I got more guitar parts around here then I'll ever use in my lifetime so donating the makes of one to someone into music and guitarless would be a good deed on my part. I'll even cover the shipping, just PM me your address.

[MikeRivers]

 

Humbuckers kill hum through phase cancellation, One coils reverse wound and has a reverse magnet. Any sine wave signal that isnt isnt being generated by both coils is nulled out.

 

 

By Jove! I think 'e's got it! This is exactly how noise is canceled by a differential input. Think of the two wires as carrying the same signal (the hum). They get put out of "phase" going through the differential amplifier and the hum is canceled.

 

Sorry to lecture here, but I'm a stickler for the terminology. Really, the output of the two pickups is opposite in POLARITY, not phase. Phase changes with time and frequency. Polarity is absolute. Check my web site for an article about this and then you can teach someone else.

 

 

So the instrument jack will take a balanced input from a mic preamp using either a TRS jack or an XLR.

 

 

First of all, it's only an "instrument" jack when you switch it to that function. Otherwise, it's a balanced line input with an impedance of about 40 k?, The XLR is designed for a mic, has an input impedance of 3 k?, and at the minimum gain setting, clips at an input level of +8 dBu. Neither the input sensitivity nor the impedance makes the XLR a very good match for the line level output that you'd get from a mic preamp.

 

When the 1/4" jack part of the XLR Combo connector is switched to Instrument, it has the same input level and gain range as the mic input (I think it's a tad hot for a guitar with really hot pickups, but that's a different story) and it has 500 k? input impedance. Also possible to use with a line level output though not the best choice. But why bother when the same jack becomes a proper line input when you click the "Line" button in the software control panel?

 

 

When a normal guitar the "Plug" is inserted, the ring is shorted to ground making the input unbalanced. How does the box know how to switch to an instrument level?

 

 

It doesn't know. You have to switch it to the Instrument setting.

 

 

As I said my guess is all the channels were breadboarded the same being balanced. The line level inputs lack an amplifier stage, and the instrument input is likely a mic level input with a 10db attenuation down to instrument level

 

 

Why are you guessing? Get one for yourself to evaluate or wait until I publish my review.

 

 

The balance is there if you wanted to run something like a balanced mic preamp in at thet level. A guitar? Well thats what this conversation is all about.

 

 

You can hook anything you want to that input. There are better and worse ways of doing it. If you want to connect a mic preamp to the Scarlett, use the front panel jack and switch it to Line. Or use one of the rear panel jacks. If your mic preamp has a line level output on an XLR connector, then get an adapter or cable that lets you connect it BALANCED to one of the 1/4" TRS jacks.

 

 

I do fully understand. You seem to be looking for loopholes in my wording. I'm sorry but its hard to break habits of a lifetime associating balanced inputs with low impedance, Give me a break why dont you.

 

 

I'm not intentionally looking for loopholes, you just keep saying things incorrectly. If someone else reads this, I don't want them to think that your guesses are correct when they aren't. It's true that guitar amplifier inputs have, by necessity, been high impedance, and by custom have been unbalanced.

 

Hi Fi from the 1950s has commonly used unbalanced connections. Phono inputs were relatively high impedance (magnetic cartridges like to be loaded by about 47 k?. Moving coil cartridges have a lower source impedance and lower level, so they got special high gain, low impedance inputs, still unbalanced because that was the custom. PA amplifiers from that era (the kind that were installed in the janitor's closet and forgotten), and home tape recorders, often had high impedance mic inputs because it was cheaper and was a good match for the cheap crystal mics of the day. Dynamic mics needed a step-up transformer to match those inputs.

 

The project studio gear in the 70s and 80s used consumer type circuitry and their outputs liked to see an input impedance of 10 k? or higher, But for the past 85 years or so, the telephone company standard has been line level (+4 or +8 dBu) balanced, at 600 ?.

 

So what's "high" and what's "low"? Today's designs are outputs with very low source impedance, generally 50 ? or less, but they're designed for "voltage transfer" rather than "power transfer" so they want to look into an input of 5 k? or higher. Still, this is mostly called "low impedance" because it's lower than what's required for a pickup.

 

 

I have in fact used the same transformers a les paul recording guitar uses in many projects where customers want low Z balanced capibility. In essecence though its the same as using a passive DI box. You just have a longer lead between the pickups and the transformer.

 

 

And this is where you get into trouble if that lead between the pickups and transformer is too long. It's why we use a DI when a guitar is played on stage but it's going direct to the console. We do that with acoustic guitars that have pickups, and with basses, but not so much with electric guitars because they just don't sound like they're supposed to without an amplifier or at least a simulator. But the idea is that you convert the pickup to a balanced line as soon as possible so you don't have hum pickup from the unbalanced cable. The fact that a DI output looks physically and electrically like a low impedance balanced microphone output is just a matter of smart design since it can go directly into a mic input on the console.

 

 

The les Paul recording guitars have the DI built in and in fact some use two transformers, one for each pickup.

 

 

I'll have to take your word on that. I've never seen a diagram of one or looked inside one. Are they conventional high impedance pickups? I guess they'd have to be with that arrangement.

 

 

II've never bothered trying it the way you're mentioning. I have no amp or preamp that has a balanced instrument level input

 

 

Hardly anyone else does either. I only brought it up here because I have a device in house now that does, and it made me think that it was going to waste with a conventional guitar, and that a guitar wired for balanced output might just have an advantage with this interface.

 

 

as you're suggesting. Line level or mic level balanced directly from a guitar pickup aould totally suck for gain and tone due to the signal strength of the pickup.

 

 

I'm not sure I suggested just that, but line level out of the pickup would seriously overdrive most any conventional guitar amplifier. And guitar level going into a "medium" impedance input like the line input jack on a mixer would be a bit shy on gain and treble. To a guitar player, that would totally suck, I suppose.

 

 

Connected to a mic level input you can attenuate the pickup signal down using passive pots in a guitar, but that makes the pickup loose its sensitivity and generally sounds like crap.

 

 

Sure, for two reasons. The passive volume control dulls the high end, and the low impedance, at least 1/50 of that of what the pickup wants to see finishes off the job. That's why smart people don't do that.

 

 

Guitar pickups require a specific impedance and gain to "play" naturally and to a great extent sound natureal. Unless you are an experienced guitarist, its unlikely you would understand the extrteme importance of this even recording a straight clean signal.

 

 

Well, really every output and input should be matched up for proper gain and loading. I wouldn't expect a guitarist to know the technicalities, but certainly he our she could understand the difference in sound.

 

 

The pickups in a les paul recording guitar are not being run balanced. Guess you didnt even look at the schematic I posted.

 

 

Really? You posted a schematic? I saw photos of guitars, but no schematic. Was it a link? Maybe I just overlooked it. Sorry. I'll look again. You look again, too.

 

 

The guitar is wired unbalanced up to the High to low impedance transformers used in the guitar. It uses two Jenson transfortmers, one for each pickup. From there to the "jack" the signal is balanced low impedance.

 

 

Surely that would work, but I guess it must have been somebody's (maybe Les Pau's) harebrained idea, or maybe he just wanted to be able to use a 100 foot cable and walk out into the audience with his guitar. For the 15-20 feet of guitar cable, there's no real reason to go balanced unless you're in a really high EMI environment. But either the amplifier would need a transformer at the input to get the level back up to what the first stage was looking for, or it would need essentially a mic preamp stage at the front end to amplify the low level guitar signal back up to guitar level.

 

My point was about the guitars passive controls. They would have to be switched from attenuating a balanced signal to attenuating an unbalanced signal.

 

 

Of course. Or maybe the best way to do it would be to leave everything as is, and put an active stage with a balanced, low impedance output ahead of the output jack (which would be TRS or maybe an XLR to confound anyone who stole your guitar).

 

 

I have an extra body and neck here and enough spare parts if you want to tinker it back together.

 

 

Thanks for the offer, but I'm not looking for another project now unless it's for pay. Wanna go into business? No, I didn't think so. Like I said, this was just a thought exercise, not an idea for a revolutionary new product.

 

Anyway, I hope somebody learned something from this discussion.

[WRGKMC]

By Jove! I think 'e's got it! This is exactly how noise is canceled by a differential input. Think of the two wires as carrying the same signal (the hum). They get put out of "phase" going through the differential amplifier and the hum is canceled. Sorry to lecture here, but I'm a stickler for the terminology. Really, the output of the two pickups is opposite in POLARITY, not phase. Phase changes with time and frequency. Polarity is absolute. Check my web site for an article about this and then you can teach someone else.

 

I have no problem with the rest of you post, but you're comparing a differential amp to a humbucker

isnt the same thing. A humbucker generates the same signal a single coil does.

 

A humbucker is two coils in series. They DO NOT "create" opposite polarity signals.

Both pickup generate positive and negative going waves depending on weather the string

is cutting the fields in a north or south going motion.

 

If both magnets were the same polarity or both coils were wound in the same direction

you would have have reverse polarity coils and you would have 100% signal cancellation of two signals

being generated 180 degrees out of phase with each other.

 

Again one coil is reverse wound and ALSO has a reverse polarity magnet so for all intents and purposes

the signals the two coils produce are in phase and the same polarity for signal generation.

In the case of a humbucker, "both coils generate a positive going signal with the string movement in one

direction and a negative going signal in the other.

 

The only thing that sees a polarity reversal is the noise and what bucks the hum is Phase cancellation of the two equal and

opposite polarity waveforms. Hum isnt being generated by the strings. the coils act as antennas and absorb the EMF directly.

 

Because the coils are reverse polarity as you call it, (magnets have no effect on EMF noise. As far as EMF is concerned they are iron core

inductors) The positive going and negative going signals are equal and opposite and cancel each other out at zero volts.

Thats it in a nutshell. To signal generated by the strings and two coils are in phase. So theres no reversed polarity as far as the signal is concerned.

 

I call what a humbucker does as purely a phase cancellation of noise induced throug EMF. The reverse wound coils are a trap for the EMF.

This trap is often called common mode rejection and is used in some manor or form in many amps including newer op and differential amps.

I think the idea dates back to much older tube amp designs. Even my old 67 bassman has negative feedback to improve High Fidelity

so there nothing new there. I believe the design dates back to earley push pull amps probibly a radio design from the 30s or 40s.

 

They do use humbucking with single coil guitars too. In a strat, the center pockup is often reverse wound and reverse magnet polarity.

This makes switch positions 2 or 4 hum bucking. They do this for Teles and others too where the center position with both pickups on

the two pickups buck the hum.

 

And if you want a simple way of converting a guitar to low Z balanced its a $10 adaptor.

Simply plug one of these in.

 

[onelife]

 

Who needs batteries? I recognize the Les Paul Recording, but what's the other one? Is that one of those stereo-wired ES-335s? If so, it probably has a TRS jack, but that's not balanced, it's one pickup on one lead and the other pickup on the other lead. But while I'm on a roll with great ideas about electric guitars that you guys can argue with me about, how about this: Connect the pickups directly to the jack (bypassing all the guitar controls) and run them into two independent channels of a purpose-built amplifier. You'd have no volume and tone controls hanging across the pickups, you'd do all of that in the amplifier itself. It wouldn't be too difficult to remote-control the amplifier's channel volume and tone controls from the guitar.

 

 

I brought up the Les Paul Recording and the Les Paul Signature (the 335 stlye guitar) because they both have low impedance pickups without an onboard pre amp. I don't know about the balanced output jack.

 

The Signature model has a switch for impedance (I assume it had an on board transformer) and phase.

 

FYI heres' a link to a close up of the controls.

[MikeRivers]

 

I brought up the Les Paul Recording and the Les Paul Signature (the 335 stlye guitar) because they both have low impedance pickups without an onboard pre amp. I don't know about the balanced output jack. The Signature model has a switch for impedance (I assume it had an on board transformer) and phase.

 

 

Well, I'll let you and WRGKMC duke this one out. He says the pickups are high impedance with transformers.