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Post by jeremylangford on Apr 29, 2008 22:51:38 GMT -5
I am trying very, very hard to understand guitar wiring, pickups, different types of grounds etc. so that I can finish shielding my standard mexican telecaster. I have already put down copper tape in all three cavitys, and have ran a wire from my neck pickup cavity into my control cavity to connect those two shields. After doing this, my shielding job has shown to be completely ineffective. I am sure that I have caused an error somewhere, because I really don't understand what exactly I am doing. I just followed the Guitarnuts tutorial as best as I could.
What I think I know is that there is a send, and a return for every power outlet, and when you plug the power chord for a amp into an outlet, this is where the whole system starts. The power goes through the send wire of the amp power chord, then into the send wire of a guitar chord, then loops through the guitar, going through the selected pickup(s), and the volume/tone controls. After this the signal has to switch to the return wire, and travel back through the guitar chord, into the amp where it is amplified through the speaker, and then back into the ground of the power outlet.
When you shield a guitar, the EM from other electronic things hits the copper tape or shielding paint that you shielded all the cavitys with, and it is supposed to find its way to the place where the "send" wires from the pickups in the control cavity meet, so that it can easily make its way back through the "send" wire in the guitar chord and into the grounded power outlet without ever going through the pickups. If all this is anywhere near correct, and the EM from the new shielding job goes into the same send or ground wire that comes from the pickups, then why isn't the EM amplified through the amp anymore?
I really have no idea how correct that is, or if anyone will understand what I mean. Thats why I am posting it here on this forum, so that I can be corrected and educated. Any insight will be greatly appreciated.
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Post by pete12345 on Apr 30, 2008 11:59:56 GMT -5
The power actually goes backwards from how you would expect it- the guitar provides a signal to the amp, while the amp does not apply any power to the guitar (unless its got big problems) The pickups in the guitar generate a signal, which passes along the cable into the amp. The amplifier circuitry boosts this signal (powered by the mains) and sends it to the speaker. The other end of the guitar circuit connects to the other side of the amp input through the cable's shielding. The 'return' side of the circuit also connects to the household ground (the third pin on the mains plug, not the neutral connection) so can be thought of as at zero volts. The shielding is connected to the 'return' wire of the guitar, which essentially encloses the electonics in a grounded metal box. Any RF interference is picked up by the shielding, and sent straight to ground through the cable. Since this side of the circuit is at zero, there is no interference. If you connected the shielding to the signal wire by mistake, you would amplify the hum as you suggested- the guitar would become an antenna and be even noisier than an unshielded one! Hope this helps Pete EDIT: I know I'm not the best artist, but you can get the basics from this: You can see that the signal, generated at the red lead of the pickup, goes into the amp and is amplified. The black lead also goes to the amp, and to ground as well. The shielding, connected to the black lead, dumps any interference to ground. Note: The amplifier should be considered a sealed unit and should not be opened unless you really know what you are doing Pete
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Post by sumgai on Apr 30, 2008 12:25:51 GMT -5
Pete, +1! This goes in my pile of reference links, right now! ~!~!~!~!~!~ jl, Hi, and welcome to the NutzHouse! ;D Pay attention to the little man behind the curtain, he knows what he's doing. sumgai
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Post by ChrisK on Apr 30, 2008 12:28:57 GMT -5
pete12345 is correct.
The amp does not "send" anything "to" the guitar. It is an amplifier that amplifies the guitar's output signal.
The guitar is a passive electronic signal generator, an alternator since an AC signal is generated.
The central ground (if you must) point is usually the counterclockwise terminal of the volume pot, often soldered to the volume pot's back shell and mechanically connected to the Tele control plate. The pickup's signal return wires (often called the "ground") should be connected to this point, along with wires from each shielded cavity individually and not "daisy-chained". Also connected here is the ground connection to the guitar's output jack (the input jack is on the amp).
The string ground on a Tele comes thru the bridge pickup's "ground" wire. The neck pickup's cover connection comes thru the neck pickup's "ground" wire.
If you used copper tape (tape being the clue since there's glue involved), you must ensure that all segments of said tape are actually in contact with each other, within a cavity directly, and between the cavities by way of the aforementioned ground wires.
If you are doing the "Shielding the Beast" exercise, you are isolating the bridge string connection, the neck cover connection, the control plate connection, the shielded cavities (the control plate likely touches one), and the pot back shells from an internal ground point that includes the CCW terminal of the volume pot, the pickup "ground" wires, and the cable shield by way of an isolation cap.
Anyway, if you are using this cap, you are creating two separate ground points, one common with the cable shield and capacitively isolated therefrom.
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Post by ashcatlt on Apr 30, 2008 12:50:52 GMT -5
ChrisK, the Tele shielding article doesn't actually include the isolation cap except as paranthetical note which links off somewhere else. Most folks who come around here talking about shielding a Tele haven't bothered to follow that link and just get more confused by reference thereto.
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Post by ChrisK on Apr 30, 2008 17:53:54 GMT -5
So I have to ask; are Strat folk less likely to be confused thereby?
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Post by ashcatlt on Apr 30, 2008 22:01:02 GMT -5
Actually... As I believe you mentioned above, the wire which carries the string ground in a tele is the same wire that carries the signal return from the bridge pickup. Also, like I said, the strat folks would have read the thing about the safety cap in the midst of their article, whereas the Tele folks are left scratching their heads saying "WTF cap is he talking about?"
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Post by ChrisK on May 1, 2008 12:50:14 GMT -5
Indeed! And that's why mine don't! I always run a separate bridge plate (not bridge pickup plate) wire to the internal guitar ground on Teles. I don't think much of contact made via a screw held against a plate by a weak spring. Also, when this is shared with the bridge pickup return wire, any signal (as in noise) induced onto the strings and bridge affects the bridge pickup signal (shared ground wire). It's bad instrumentation (as in signal instrumentation) practice.
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Post by jeremylangford on May 1, 2008 18:00:24 GMT -5
Actually... As I believe you mentioned above, the wire which carries the string ground in a tele is the same wire that carries the signal return from the bridge pickup. Also, like I said, the strat folks would have read the thing about the safety cap in the midst of their article, whereas the Tele folks are left scratching their heads saying "WTF cap is he talking about?" What is the purpose of a singal return and also a string ground?
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Post by ChrisK on May 1, 2008 20:08:38 GMT -5
While most guitar wiring is described in terms of "hot" wires and "ground" wires, this is minimalistic and misleading. These wires are only those points if they are connected to those points. I prefer to use the names "signal output" and "signal return" since these refer to the wires necessary to convey a signal from something (the proverbial complete circuit). The signal return wire from a pickup is usually connected to an internal point that is usually connected to the cable shield and eventually to the (maybe) safety ground on the amp. The signal output is usually eventually connected to the signal input to the amp via the internal signal wire in the cable. But, if two pickups are connected in series (most pickup switching connects them in parallel), the signal output from one goes to the amp signal input and its signal return goes to the signal output of the other. The others signal return goes to the cable shield and eventually to the amp "ground reference point". And, if isolation techniques are in use, there is more than one "ground" afoot. The signal return is the second wire that enables the complete circuit from that component into the circuit afoot. A pickup will have a signal output (an arbitrary designation) and a signal return (another arbitrary designation). If one reverses said connections from all pickups in a guitar, it will work exactly the same. Think of a battery. It has a positive terminal (positive with respect to the other terminal) and a negative terminal (negative with respect to the other terminal). In a U.S. automobile, the negative lead is connected to the vehicle's chassis (the GROUND) and the positive is switched to the loads (which are connected to the ground - a complete circuit is). In days of old, my father's VW had the positive lead connected to the chassis (gasp, the GROUND), and the negative lead was switched to the loads. In the first example, the battery had a positive lead and a ground. In the second, a negative lead and a ground. These were not interchangeable, but both worked fine when left alone. Understanding the semantics is key to understanding the circuits. The string ground is the connection of the bridge and hence the strings to the cable shield to avoid having the strings float electrically and pick up noise. For every time where one just connects one wire from each pickup and wonders why nothing works, there are more times where one connected the "hot" leads from their pickups to the new-fangled switching scheme and all "ground" wires from the pickups to "ground", and nothing works or some things work. Understanding things "component" as they are is fundamental to understanding things "circuit". That whole "tremolo" fiasco started when words were used without concern as to what they actually meant. We ended up with the "wiggly bridge" on most Strats that changes the pitch of the string tuning called a "tremolo" (the tremo'Leo) because the engineer and musicians involved knew little about music theory. We ended up with the varying amplitude loudness on an amp called vibrato (aka the Vibroking/Vibrolux) when in fact it is tremolo. Interestingly enough, you can get a Tele with a tremo'Leo, unless it's a Bigsby, which then is correctly called a vibrato. I started to make these points since the initial poster indicated that they were having a hard time understanding "guitar wiring, pickups, different types of grounds etc." Actually understanding the differences is fundamental to actually understanding the differences.
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Post by jeremylangford on May 4, 2008 20:55:23 GMT -5
Ok. So a guitar pickup sends out two wires to the amp. A signal output and a signal return. But they are both technically part of the same exact wire right? Just two ends of the coil that wraps around the magnet in the pickup? Is one wire positive and one negative? Does the current in both wires travel to the amp and never from the amp to the guitar, or does the current in the signal return wire travel from the amp to the guitar so that it returns back to the signal output wire?
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Post by ChrisK on May 4, 2008 21:49:51 GMT -5
A guitar has two wires connected to the amp. This is a fundamental concept in that the signal generator (the guitar) has TWO wires connecting it to something else. ANY component (a devise with characteristics beyond that of a simple wire) has to have at least two connections to it to form a complete circuit (as in a race track circuit or loop). While an antenna may appear to have only one terminal/connection, its other "connection" is the earth. Yes. Yes, but only from the perspective of "just a wire" with small diameter and significant resistance. Oh wait, the significant resistance (in the case of a passive guitar circuit, more than a few few) makes it at minimum a "resistor". No actually, since the resistance, inter-winding capacitance, and inductance (created en mass from those many turns of wire and enhanced by the iron in the cores) and signal generating capability (from those many turns around a magnet) create a component (a device with characteristics beyond that of a simple wire). A guitar pickup is no more a simple wire than an AC motor is just a wire. Usually/mostly. The signal generated by the pickup is an AC signal. It is made up of sine waves of various (hopefully harmonically related) frequencies. At virtually any given instant, one wire is more positive than the other in a varying amount. At some rare but periodic instances, there is zero output. Exactly half of the time one specific wire will be more positive than the other. A complete circuit is in effect from the guitar to the amp. The pickup(s) generate an AC signal that flows thru the complete circuit comprising the guitar circuitry, the cable, and the amp's input circuit. This circuit is isolated, except in the case of the safety ground or neutral (in the case of unsafe "Vintage" practices) connections. I would not use the same colors for the mains hot and neutral as the two connections from the guitar. While in concept the operation is identical, they should not be related/common in any connection. I would suggest that basic electronics in the form of a text or local course be obtained to gain familiarity with electronics theory and electrical codes. Attempting to fully understand guitar wiring/shielding is better realized once basic circuit theory is assimilated.
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Post by jeremylangford on May 4, 2008 22:16:46 GMT -5
Im sorry Im having so much trouble fully understand electric guitar pickups. Ive just been trying to shield my guitar for a long time with no success. I play guitar at church and in the building I play in, there's a lot of rack lights that have dimmers. This makes my tele go crazy whenever the lights are turned on. Whenever they're turned off, the buzz completely stops. The buzzing is soo bad that I can't even stand to play anymore. I borrowed my friends Epiphone SG and played it with all the same equipment, in the same exact place, and the humbuckers got rid of all the hum completely.
I just want my tele to have the same amount of buzz as humbuckers. (Or at least closer than they are now)
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Post by jeremylangford on May 4, 2008 22:28:32 GMT -5
Does this image seem right. The green arrows are representing which way the current is flowing.
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Post by ChrisK on May 4, 2008 23:01:12 GMT -5
No!
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Post by sumgai on May 5, 2008 0:59:26 GMT -5
jeremy, OK, I see the problem here......... First, Chris said NO! because you used the standard reference for household power found at the wall outlet - we call that stuff AC almost universally (and not AC current, that'd be redundant). Your arrows also raise a solid NO, because they go in the same direction. What Chris has been trying to say is that current flows in one direction at a time, all the way around a circuit, from start to somewhere (that we usually call a load), and back to the start. That's what he meant with the race-track analogy. Let's get real basic here. In order to attach any labels to an electrical circuit, we need to keep in mind that all labels are in reference to something else. That's the number one bugaboo about electronics - it's easy to forget that little rule of thumb. So when we say Hot or positive (+) or signal output, we're really making that designation in relation to another part of a component, or to another part of a circuit. In this example, I could be saying 'the positive lead' of a pickup, and I'd be referring to one of the two leads that is intended to go out to the controlling components (the selector switch, the pots, etc.). That reference is directly related to the other lead of the pickup (the negative one, or signal return). We usually attach this to ground, which is a common connection point, but of course, that's not a requirement. In fact, using the word "ground" is so common place that we tend to forget ourselves, and over-use it in our conversations. Which is why Chris has (rightly) started pounding the pulpit about using the more correct term "signal return" instead of 'negative lead'. (And even there, positive and negative are truly misnomers, we use them only for convenience, and because + and - are easy to type. ) Let's go further........ Now I wanna say "Hot" when talking about the output jack. That's in relation to the other terminal, commonly called "ground". Again, those terms are conventional only for convenience, they truly are misnomers because in an AC world, the polarity keeps changing! But the ground terminal is most often connected to the chassis of the amp (through the cord), and the chassis is usually grounded via the power cord, hence the terminology. But we're really using "Hot" here to refer to one side of the circuit, not just a component, and ground is the other side, where the signal will return (in very short order, at about the speed of electricity . As noted by Chris, the two points are at opposite polarities at any moment in time (unless there is truly no signal at all). Now, to cement all this (I hope!), just remember that it's called "signal return" for a reason - the signal has to come back in order to complete the circuit, but just as importantly, the return point is also the reference point for what we call "Hot" or signal output. Once we have our reference point taken care of, we can attach labels to other points of interest, and (hopefully) we'll all be on the same page. ;D HTH sumgai
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Post by ashcatlt on May 5, 2008 15:48:44 GMT -5
This might come across as contrarian, and is really off topic, but ChrisK said: Exactly half of the time one specific wire will be more positive than the other. Exactly is a pretty strong word, and in this case not exactly accurate. It might be true if we all played with e-bows, but most of us excite the string using some form of pluck. Whether we use a pick, our fingers or whatever, we usually start the string moving by giving it a fairly large and fast push in one direction or the other. If there were no such thing as friction, magnetic drag, air resistance, gravity, etc, we would expect the string to rebound to a distance equal to its initial deflection on the other side of its rest position. We would also have sustain which would make the finest Les Paul hang its head in shame. Unfortunately, most of our guitars live in a real physical universe, and so the string never moves so far as it does on that first whack. If we spent the time and did the calculus I'm pretty sure we'd find that the area under the curve of a single note from a guitar does not equal 0. Whether the result is + or - is essentially arbitrary. It depends on the direction of the initial attack as well as both the winding direction and magnetic polarity of the pickup.
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Post by sumgai on May 5, 2008 18:46:43 GMT -5
ash, You are correct, for your part of the world, that of the string. Chris is correct for his part of the world, electrical phenomena. The only possible addendum to his statement would be '... while there is a difference in potential". Obviously, when the voltage is crossing the zero point, both potentials are equal, and therefore neither wire will be more positive than the other. Seeing as how the speed of electricity through a wire is a tad bit quicker than the speed of sound through air, I don't foresee much difficulty in an electrical circuit being able to complete a full cycle before decaying to virtually zero potential - regardless of the physics of the plucked string. HTH sumgai
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Post by ChrisK on May 5, 2008 18:54:17 GMT -5
I've actually stopped responding to this thread in any technical detail since there are two different themes afoot.
The first is a desire to get one's Tele to stop picking up noise. In this case, shielding IS exactly the issue.
There are two possible paths, both of which need be directional rather than theoretical.
A. I'd suggested (some things via PM) that a detailed inspection of the shielding implemented be performed to ensure continuity. Glue can be an insulator.
B. I'd suggested that humbucking pickups such as SCNs or such be used since his friends SG has no issues in the same venue. (No shield can be perfect/complete.)
Second, while we labor to exude exact statements regarding the minutia of AC circuit theory in terms both simplistic and complex to help explain the actions of EMF, the real issue is that of a common visualization framework.
I've suggested that a text on basic electronics be ingested prior to continued theoretical discussions on shielding one's Tele since it became most clear that we're not "seeing" the same city, let alone the same "race track".
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Post by jeremylangford on May 5, 2008 20:52:25 GMT -5
I've actually stopped responding to this thread in any technical detail since there are two different themes afoot. The first is a desire to get one's Tele to stop picking up noise. In this case, shielding IS exactly the issue. There are two possible paths, both of which need be directional rather than theoretical. A. I'd suggested (some things via PM) that a detailed inspection of the shielding implemented be performed to ensure continuity. Glue can be an insulator. B. I'd suggested that humbucking pickups such as SCNs or such be used since his friends SG has no issues in the same venue. (No shield can be perfect/complete.) Second, while we labor to exude exact statements regarding the minutia of AC circuit theory in terms both simplistic and complex to help explain the actions of EMF, the real issue is that of a common visualization framework. I've suggested that a text on basic electronics be ingested prior to continued theoretical discussions on shielding one's Tele since it became most clear that we're not "seeing" the same city, let alone the same "race track". Yea. I do need to understand the basics of electronics and AC vs. DC. I am getting ahead of myself right now. The reason I posted that picture with both green arrows going the same way is because my inital question in this thread was if there is any power that goes from the amp to the guitar, and I was told no. This made me misinterpret the signal return wire and made me think that I needed to make both the arrows go from the pickups to the amp. I think I am starting to understand it better now. I think the current starts in the pickups, then goes through the signal output wire, through the amp, and then after it gets to the speakers, the current goes into the signal return wire, to ground via the amps power chords, then back to the pickups where the AC started in the first place. Is that anywhere near correct?
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Post by ChrisK on May 5, 2008 22:02:46 GMT -5
What you are describing is an extreme simplification of the overall circuit of the guitar, amp, speakers, and AC mains. It is so simplified that we all are worried in various ways about this description possibly confusing things enough that you'll inadvertently do something that will "turn you into toast", or might lead the casual reader to do so (themselves, not you). What you are describing is the "signal information flow process" from the guitar thru the amp to the speakers. Forget about the mains, it's just the source of power for amplification. The guitar signal circuitry, in conjunction with the amp input signal circuitry, forms a complete circuit which is comprised of loops often within loops. In essence, the minuscule signal output of the guitar is amplified by the first stage of the amp. It's output signal, an amplified copy of the input signal voltage, goes to the second stage. Eventually a stage drives the power output stage which performs current amplification such that the signal is a copy of the input signal with sufficient voltage and current gain to effectively drive the speakers (THE LOAD). The power supply, which happens to be connected to the mains, develops sufficient voltage and current to enable the amp signal stages to amplify the signal and to drive the load. In ALL cases, the mains must be isolated from the power and signal stages except for safety connections. Many early amps did not do this well. They should not be used. The connection point between the stages is the ground point, most hopefully connected to a safety ground. The first stage will take the guitar output signal, referenced to the ground point and develop its output signal, usually referenced to the ground point. This is true for each stage. The DC power supply is referenced to the ground point. The mains input goes only to an isolated primary winding on the power input transformer. While some minute current can flow from one stage to another, to/from the power supply, and even to the speakers (assuming that there's no output transformer), it is minute and of NO CONCERN to this discussion. If it is NOT minute, it IS of concern to safety. So, while there is signal information flow from the guitar to the amp and then to the speakers, there is not a circuit that directly takes the output of the pickups thru the amp to the speakers thru/to the mains and back thru and into the guitar. If this does happen, don't touch anything, it's gonna get "toasty" if you do. The amp produces a high powered copy of the input signal to drive the speakers. For shielding purposes, one needs to completely and properly shield the pickups and wiring within the guitar, and to connect said shield to the guitar cable. A functioning cable will connect said shield to the amp shield reference point. That's the best we can do and hope for. And, it's a shield. It's not perfect or complete. If you want to consider single coil-sized hum canceling pickups, don't forget about Bill Lawrence. www.billlawrence.com/Pages/Wilde%20USA/WildeUSA_Pickups.htmI notice that the off-site reviews of these pickups state the output in Henries. Gee, at least it's not in Ohms! (I invented a solar cell with an output in Farads, but no investor had the capacity to understand it.) (Why did Mickey Mouse divorce Minnie Mouse?)
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Post by ashcatlt on May 5, 2008 23:09:45 GMT -5
Yeah, that was the real point of most of the posts above. You do not want the mains voltage inside your guitar! The specifics of how the signal gets amplified are a little more complex than "basic" electronics theory. My oversimplified explanation (which actually kind of exists in far more accurate languate in ChrisK's post above) would be that the AC mains voltage is converted to DC, which is then sort of modulated by the signal coming from the pickups to approximate the motion of the string. This process is usually repeated a couplefew times before finally being fed through the circuit to which the speakers are connected. It's likely that the majority of the discussion above belongs under some other topic. I have to admit that I'm not completely confident in my understanding of why shielding works. I take it on faith, I guess, but every once in a while I get to the idea that the noise signal is an AC source, and shouldn't it be trying to move in both directions? The best thing I can come up with is that all current wants to move toward the earth via the least resistance possible. I think that's because the earth itself has plenty of atoms to help equalize a small "misappropriation" of electrons. If you connect the noise signal on the "ground side" of the guitar circuit, the current has two choices. It can either go through thousands of ohms of pickups and then a million ohms of resistor at the amplifier input, or it can through somewhere very close to 0 ohms resistance at chassis ground. Which way would you choose? But, again, I'm not the least bit sure that's anywhere near accurate, and mostly just take it on faith. Now, back off topic for a second - sumgai, it wouldn't be the first time that I'm missing something very basic that keeps me from understanding where you're coming from. Seems to me, though, that all of the current in the guitar is dependant on the motion of the string. If one were to take (for example) a screwdriver and move it in exactly one direction within the magnetic field of the pickup, and graph the voltage output, one would expect that graph never to cross the 0 line, no? On the other hand, if you moved it 2" in one direction, then back 3", you would plainly see that the graph spends more of its lifetime on one side of the graph than the other. You could (if you'd like) decide that the 0 point of the graph should be the average of the function, but that doesn't really represent the current flow when the screwdriver is at rest. Seems that the string/pickup combination has a pretty distinct 0 point where the string is at rest, and that if the string moves further in one direction with respect to that point between the time when it starts moving and when it stops... [long pause to figure out how to end the sentence] ...well then I'm right, whether I can get my point across to anybody else or not. I've spent quite a lot of time looking at waveforms in various editing programs, and I know for a fact that guitar waveforms are generally not perfectly symetrical.
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Post by sumgai on May 6, 2008 23:08:20 GMT -5
ash, I can't think of a smart-butt answer, so I'll have to play the serious card, sorry. <Professor's Hat on>As it happens, the answer to your question is the same as to Jeremy's. Chris hinted at it, but in plain language, the electrical current we use to power our amplifier is nothing more than a carrier for the signal we impose on it, via the amplifier's circuitry. The current generated by the pickup modulates the current being passed around within the amplifier's various stages, each stage modulating the next, until the final stage modulates the speaker. (Well, technically speaking, the speaker transduces that electrical energy into magnetic energy, which is then transduced into mechanical energy, which we perceive as motion. More on this as we go along.) Now, given that we have an electrical current that is generated by the pickup, how fast is this current traveling? Easy, at the speed of electricity - Q.E.D. But how do we have a sound, that's not the same speed? Again easy - the sound is modulating the electrical current at an audio rate. That's a modulation of one waveform onto another.* To get more precise in reply to your statement, yes, a string that vibrates a slight bit assymetrically does indeed cause the electrical current to be biased one way or the other about the base reference line (the point of Zero volts output). But that holds only for the initial pair of swings. Once the vibrational rate has been established, the base reference line is, for all practical purposes, adjusted to be between the two extremes. This is easy to see when you think about it - the initial force that started the excursions no longer applies, so the only thing keeping the string vibrating is inertia. Each excursion will be a tiny fraction weaker than the previous one, but the overall decay is such that we can't detect this particular phenomenon without some rather expensive test equipment. (Which Murphy's Law says will always be in another city! ) Sound, by its very nature, is a vibrational phenomenon, and a quick look-up of the definition of vibration is a "back-and-forth motion". So what's happening when you drag the screwdriver off the magnet in one direction? Not as easy to see until you think about it, but the screwdriver tip is not sliding noiselessly across the magnet, there is a vibration going on. Don't believe me? Do this without the amp, and listen closely to the screwdriver/magnet interface as you move the former over the latter. Hear that? The amp is picking that up, because the magnet is being modulated by an audio waveform, and the coil is transducing that into an electrical signal to be used by the amp. Let's look at a similar component, at the other end of the chain. If you move a speaker cone forward to its range limit, and keep it there, would you hear any sound? No, of course not. It travelled a tiny bit in one direction, and stopped, hence, there was no vibration, and as we just saw above, there was no audio signal for our ears to detect. The cone has to travel back and forth in order for us to hear any sound. Same thing for a pickup. If the string were to move in one direction, and then stop, there'd be no vibration, and hence, no audio energy to excite the magnetic field. When you look at a graphic representation of screwdriver being pulled up off of a magnet/coil, you're seeing a momentary rise in one direction or the other, that's true. But what you're really looking at is the shift in the zero line, not an electrical current. The shift is a temporary, because the field expands, then collapses, albeit only in one direction. If you want to see this in action, simply watch the 'scope as a string is vibrating, during which time you drop the screwdriver tip onto the magnet. Mayhem for a moment, then all is restored to normal. But that momentary shift is nothing more than an applied bias, that's all. Bear in mind, it is possible to excite a magnetic field in one direction, and have it stay there. The temporarily excited field will induce a pulse within the coil, and that pulse will be replicated by the amp. What's it sound like? Like a thump - it was a momentary bias imposed (modulated) onto the electrical circuit, and it lasted only as long as the excitation lasted. When the excitation stopped, the electrical signal also stopped because there was no more change in the magnetic field. Could you really hear this kind of action? Yes, probably, given that the pickup coils are quite sensitive, and the amplifier is quite powerful. But could you actually induce it? Not easily. Doing so is an exercise best left to the student. ;D <Professor's Hat off>HTH sumgai * For a visual understanding of this modulation, look more closely at Chris's (most excellent) reference on Harmonics/Frequency/Theory. Specifically, this link shows the interaction of one waveform upon another. Select Sinusoid 10, and watch how the smaller waveforms modulate the actual voltage level of the larger waveform at any given instant. That's the very definition of modulation. HTH
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Post by jeremylangford on May 10, 2008 19:28:36 GMT -5
I went to Guitar-Center today and asked a guy that works on guitars about my whole buzzing problem and told him I tried to shield my cavities with no success.
He said that the problem is definitely my pickups and shielding wouldn't help me much.
I am planning on buying the SCN telecaster noiseless pickups and trying them out. Im pretty sure that this will stop all my buzzing and humming. Any suggestions on the cheapest place to purchase these?
Is it possible that I might have to also change out all my wires and pots as well?
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Post by ashcatlt on May 11, 2008 1:15:59 GMT -5
Are we really that bad? I thought someone had adressed your concerns in fairly straightforward manner a while back, before everything went weird.
You know that the guy there at GC is likely specialized (at best) in sales. He's probably not much of a tech and almost assuredly not an electrical engineer like some of the guys we've got around here.
So, you know, how do you think dude's comission check would look if all you did was go home and shield your guitar? They don't even sell most of the required materials. On the other hand, if he can talk you into a set of shiny new pickups...
Course they probably will help, since that's what they're designed to do.
(I guess you said he "works on guitars" so, by definition, a tech, but still a bit suspect)
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Post by newey on May 11, 2008 10:21:35 GMT -5
Ash (and, by extension, Jeremy):
It didn't go weird, it got technical. This is a good thing, since the resultant thread is helpful to a deeper understanding for many, not just for Jeremy. It certainly clarified a few of the concepts in my own mind.
And Jeremy asked 2 questions, one about shielding his Tele and the other about electrical theory. I believe both were answered somewhere along the way.
So, Jeremy, as ChrisK suggested, you should check your shielding for continuity between each piece of foil/tape, and also double check the grounding of the shielding in each cavity. You should probably do this even if you decide to switch to the SCNs. Since you've already shielded it, best to make sure the shielding is done correctly in either event.
And Jeremy, you asked 2 new questions:
Not unless you have reason to believe there is a problem with these items. If you mean change them because they might be contributing to the noise, it's unlikely they are having any impact on that, your pickups are the big noise generator in most cases.
I'll look around, I'm thinking of a pair myself.
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Post by newey on May 11, 2008 10:53:49 GMT -5
Jeremy- Cheapest I saw was MF at $134.99 for the set. SCN Tele SetList is about $175, I saw them several places for $159, so MF is pretty good on this- free shipping too. They also have the Vintage Noiseless Set for $115. I don't know how these compare to the samarium cobalt ones for noise reduction, however. The Vintage ones are clearly less "hot" tone-wise, according to the description. If you're not wedded to the idea of gen-u-wyne Fender parts, there are several other options out there, some of which may be a bit cheaper.
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Post by lpf3 on May 11, 2008 12:15:27 GMT -5
Guys - Check out the thread " opinions on Fender noiseless pickups " in the pickups aisle of this forum . To quote ChrisK , last June 26: This is why I don't care for hot pups - seems to me if you start with " bright and crisp " you can always get " middy and thick " out of your amp , effects , etc . But if you start with " middy and thick " well , there goes yer Fender sparkle . Jeremy - I have the cheapest Tele you can get ( affinity series ) with the pups you'd expect in a cheap Tele & the hum is not that bad , I would backpedal a bit . Before spending the money on new pups , check ( and re-check ) your work to make sure all is as it should be ( cheaper ) Unless you just want a set of Noiseless SC's...... I know I do . Good luck -lpf3
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Post by jeremylangford on May 11, 2008 12:52:02 GMT -5
Guys - Check out the thread " opinions on Fender noiseless pickups " in the pickups aisle of this forum . To quote ChrisK , last June 26: This is why I don't care for hot pups - seems to me if you start with " bright and crisp " you can always get " middy and thick " out of your amp , effects , etc . But if you start with " middy and thick " well , there goes yer Fender sparkle . Jeremy - I have the cheapest Tele you can get ( affinity series ) with the pups you'd expect in a cheap Tele & the hum is not that bad , I would backpedal a bit . Before spending the money on new pups , check ( and re-check ) your work to make sure all is as it should be ( cheaper ) Unless you just want a set of Noiseless SC's...... I know I do . Good luck -lpf3 If you were to see the place I play at youd understand. Its a stage and there a bunch of huge racks with lights all over them that have 10 different presets of dimness. They just shine straight down onto my pickups.
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Post by lpf3 on May 11, 2008 13:31:47 GMT -5
jeremy-
Yeah , I noticed you said your friend's SG solves the problem .......
So , if that's the case & you do get SCN's , let us know what you got & how ya like 'em . I've been thinking about the Fender Vintage ones for my Tele .........
-lpf3
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