Input Jack

[Devon8822]

On my input jack in my guitar does it matter which lug the ground and the signal wire is connected too? Can they be switched? or does each wire have to be connected to a specific lug on the jack?

[Tim37]

yeah if you look yoiu will be able to tell whitch lug is connected to the long lug that comes off the center you need to make that your positive.

[Samba Pa Ti]

connect the signal wire to tip, ground to the outside.

like tim said, have a look at it, the tip is easy to spot (it touches the end of the plug when its plugged in).

[Prostheta]

It matters hugely. Both ways will work, although one will cause huge amounts of noise, buzzes, crackles, etc. as you will no longer have a correct earthing. Plus your tone will be upside down if you check it in an oscilloscope.

[ihocky2]

It matters hugely. Both ways will work, although one will cause huge amounts of noise, buzzes, crackles, etc. as you will no longer have a correct earthing. Plus your tone will be upside down if you check it in an oscilloscope.

That might be usefull if you're playing on a Tommy Lee type rotating platform.

[Paul Marossy]

Just for the record, it's an output jack not an input jack. The signal goes from your guitar out of the jack and to your amp. It's not receiving a signal from something else and into the guitar.

Edited April 19, 2010 by Paul Marossy

[Tim37]

btw it would really be important if you have every thign shielded and grounded because at that point theres a good chance that you could simply short out the signal and get no sound if it's backwards.

[ShadesOfGrey]

Just for the record, it's an output jack not an input jack. The signal goes from your guitar out of the jack and to your amp. It's not receiving a signal from something else and into the guitar.

Well, that depends from what type of engineers eye's you look at it.

From a audio engineer or amp builders viewpoint, the audio 'signal' exits the guitar from the jack to be fed into the amp.

From an (general) electricians viewpoint, current *enters* the jack to the humbuckers (where it's modulated)

Remember that it's the amp supplying the electricity!

So you can either see the jack as transporting an audio signal, or as transporting current to the guitar.

[Paul Marossy]

It´s not the amp supplying the electricity for the circuit. The pickups (magnets surrounded by wire) provide the electricity for it, besides sensing magnetically the strings´movement. That in case of passive pickups. In the case of actives, a battery has to be supplied as well.

That's 100% correct. The pickups sense the movement of the strings, and a small electrical current is generated as a result. The pickup outputs a weak signal which the amplifier then amplifies quite a lot to make it useful. If an amp is feeding the guitar current, then something is very wrong with the amplifier and it is a potentially deadly situation.

The jack on a guitar is always an output jack, signal and currentwise.

[Tim37]

a pickup is nothing more that a generator. that generated signal is then fed in to a amplifier the amplifer does just that it amplifies the signal. then sends it out to the speaker.

with active pickups, the pickup does the same then it goes to a peramp to raise the signal to the desired rate. btw frome what i understand about emg is that they wind there pickups with tone and sound being there first priority and use the electronics to bring the signal up to the desired level. when winding normal pickups you have to balance the tone and sound with desired output thats what makes winding picups such a artform.

[Samba Pa Ti]

a pickup is nothing more that a generator. that generated signal is then fed in to a amplifier the amplifer does just that it amplifies the signal. then sends it out to the speaker.

with active pickups, the pickup does the same then it goes to a peramp to raise the signal to the desired rate. btw frome what i understand about emg is that they wind there pickups with tone and sound being there first priority and use the electronics to bring the signal up to the desired level. when winding normal pickups you have to balance the tone and sound with desired output thats what makes winding picups such a artform.

not arguing with you but what i heard about EMG is that they keep the pickups sterile sounding so they get more accurate sound from the strings, then effects and all that jazz add the tone...

cant remember where i read that but whats your take on it ? ive never used EMG's but ive always fancied trying some

[Paul Marossy]

Active EMG pickups are low impedance types. You don't have to worry about cable lengths and stuff like that much with them. And because they are low impedance with a preamp, they are much less susceptible to noise.

http://www.emginc.com/pages/whyemg

Regular passive pickups are high impedance and pickup noise quite easily in comparison.

[Tim37]

they are low impedance because they have a built in buffer.

i have a KFK set (85/81 pa-2) personaly i dont find them sterile. i love they way they react to the tone and volume knob you can roll the highs off with the tone knob and not loose the edge that happens with passive pickups (i hate using the tone knobs on my other guitars) and i know they have the reputation for just doing metal but i find they clean up and do reall nice blues tones too.

[Ripthorn]

they are low impedance because they have a built in buffer.

i have a KFK set (85/81 pa-2) personaly i dont find them sterile. i love they way they react to the tone and volume knob you can roll the highs off with the tone knob and not loose the edge that happens with passive pickups (i hate using the tone knobs on my other guitars) and i know they have the reputation for just doing metal but i find they clean up and do reall nice blues tones too.

I find the 85 especially to have quite a bit of character. It is probably my single favorite pickup and I don't really do metal (classic rock and blues, mostly).

[Samba Pa Ti]

they are low impedance because they have a built in buffer.

i have a KFK set (85/81 pa-2) personaly i dont find them sterile. i love they way they react to the tone and volume knob you can roll the highs off with the tone knob and not loose the edge that happens with passive pickups (i hate using the tone knobs on my other guitars) and i know they have the reputation for just doing metal but i find they clean up and do reall nice blues tones too.

i hate the tone knob on a lot of my guitars as well, only pickup i use it on is a super distortion 2 as the tone knob adds more grit :S

[ShadesOfGrey]

Hmm, I stand corrected on the amp feeding the current part.

Put my multimeter on a few humbucker I had lying around. Waving a screwdriver in the magnetic field most decidedly results in a current. Actualy, you can see the difference between how 'hot' a pickup is.. the Seymour Duncan Invader gives a lot more juice than the SD Jazz I tried before that.

But I really thought the pickups were part of a closed circuit with a current travelling *through* it, and the string vibration would modulate the magnetic field and therefore modulate the circuit.

Thinking about it, it doesnt make sense though.. because that would probably mean that the signal should result in more loudness if you dont play. Also, it should result in a more powerfull magnetic field if you plug it in, which is bollocks. And where the hell does the remainder energy go? Not as mechanical action, heat & light seems off, and I cant see it resulting in radiation.

But yeah, most I know about electrickery was from a few lessons on the subject in highschool physics. And could then hardly tell my capacitors from my resistors.

At least I know the difference between volts and amps

[Paul Marossy]

Electric guitar pickups are really nothing more than specialized microphones that use a type of transducer that senses the movement and frequency of the guitar strings and converts that to an electrical impulse rather than the type of transducer that you would find in a hand held microphone, which picks up actual sound. Neither of them have the amplifier sending current thru them. They both send very weak signals to an amplification system which has to amplify them quite a bit to be useful.

Open systems vs closed systems is really more applicable to pumps and that sort of thing. Every circuit is a "closed system", if you will. If you leave out a piece of the circuit out, then it won't work. It's basically a loop. If you connect one terminal of a light bulb to the postive on a battery but don't connect the other terminal to the negative on the battery, nothing will happen.

In the case of the electric guitar, it is sort of an "open system" in the sense that the hot signal gets sent to the amplifier, but the amplifier doesn't need to close the loop, it just takes what is feed to the input and amplifies it. If the loop is open in the amp, then it will try to close it and complete the circuit by using your guitar to send current thru, which means that YOU become the path to ground, which is potentially fatal. The ground on the guitar serves a few purposes - it is there for safety and it also gives the amplifier a reference to ground, which it needs because it is being fed with an alternating current from the guitar pickup(s) and it helps control unwanted noise by shunting it to ground (EMI & RFI). Using hydraulic terminology, it's sort of like a side arm chemical feed to a closed loop pumping system.

Or here is another roughly similar analogy: think of the power section of an amp as a closed loop piping system connected to one side of a heat exchanger. The heat exchanger is the interface between the guitar and the amp, we'll call it the preamp. The other side of the heat exchanger is connected to the open loop pumping system, the guitar. If the heat exchanger were to fail because it ruptured internally, then the two flows would mix and both systems would then be experiencing a massive failure.

Does that make sense?

Edited April 21, 2010 by Paul Marossy

[ShadesOfGrey]

Or here is another roughly similar analogy: think of the power section of an amp as a closed loop piping system connected to one side of a heat exchanger. The heat exchanger is the interface between the guitar and the amp, we'll call it the preamp. The other side of the heat exchanger is connected to the open loop pumping system, the guitar. If the heat exchanger were to fail because it ruptured internally, then the two flows would mix and both systems would then be experiencing a massive failure.

Does that make sense?

Actualy, yes that makes sense. Good analogy, thanks

But I always figured the ground of the guitar wasn't just ground but also doubled as a sorts of return to make a loop? I've always been taught that current doesnt just happen, it's the flow that matters and that is why you have loops. If you break the ground, the circuit is also broken. Or am I missing how the amplifier figures in the equation? Does the amp supply ther pole to the guitars pickup or something?

Or does it work with a more static charge differential from the pickup?

I'm a bit ignorant on the subject I guess, but I'm genuinly intrested.

[Paul Marossy]

You can break the ground connection on the cable connecting your guitar to the amp and the amp will still pick up the signal from the guitar, but you may have some noise problems because the signal ground is now "floating". The ground in this case is really more of a way of shielding from extraneous noise and safety thing. It does help the amp with a reference to ground as far as the signal is concerned - it's not absolutely necessary, but optimal.