AndrewCE

i've already done that to my guitars ( I actually have a thread about it on this board somewhere). It works pretty well, but the volume taper is not quite the same. It only fights against the cable capacitance, but it would still be better if you could eliminate the capacitance.

actually i've never done a blindfold test between cables but i have rolled down my volume control and noticed that it gets muddy. "muddy" not "thick" or "heavy". Simply cutting highs makes something sound muddy. and even if there's not noticable difference, all those little things all over your sound combine to make a significant difference even so, i personally don't think $50 is reasonable for any guitar cable, even a 0mF cable

OHHHHHHHHH okay, yeah then that's what I was describing. so it will work, with the resistors. K thanks! as long as the signals dont travel through the resistors anyways...

But your diagram had resistors before the op amp. I'm saying if a resistor was after each parallel voltage follower. Surely they wouldn't act the same way.

WOAH i disagree there. Cable capacitance does play a role in guitar tone; you lose high end, especially with the volume pot turned down.

psw, do you mean that the signal produced by part A (pickup A in series with voltage follower A) will try to run through part B? I don't think a signal can enter the output of a opamp. Unless, as I was thinking earlier, signal A entered the output of voltage follower B via opamp B's inverting input. Would this happen? And could it be stopped by adding resistors after each voltage follower?

hmm, thats exactly what i was afraid of. sorry but i still don't understand your "If you connect two zero impedance voltage sources that are different in voltage, the voltage difference divided by the impedance (zero) means it would try to deliver infinite current." Do you mean voltage follower A would try to deliver infinite current into the output of the voltage follower B? now what if you put a resistor after each voltage follower, and THEN brought them together. Then the impedances would not be zero. Would that produce "A+B"?

oh and long pots distort a bit smoother than short ones, but they lose some high end. HAHA jk

that would be correct well, technically depending on thick vs thin. but carved tops are generally thick and noncarved have thin wood top.

hmm i'm not sure i'm understanding your explaination here. What is "interaction due to loading" referring to? What is loading what? You have 2 low impedance sources in parallel, why would the 2 voltages not just average each other?

but there is theoretically infinite current gain, that's how the voltage follower has low output impedance ...right? and why would there be distortion, if a pickup's signal is only a few millivolts and I supply the opamp with +-9v?

so...it will accept any input and give out an exceptionally low output... Now mixing a passive pickup with an active pickup is notoriously troublesome and the control pots are likely to need scaling back to work properly for the active, but not for the passive...if you buffer after the controls...you are likely to induce noise and scratching from the high pots. A common strategy with opamp designs is to bridge the input to ground with a 1M or so resistor, this gives the input a 1M input resistance similar to the impedance of a guitar amp. This is just one of the many little design subtlties with working with circuits and guitar impedances. Again...not sure I am understanding the application... SO...opamps are often regarded as cold...at the least "overdone". If you find a diagram from a data sheet say of the inside of an opamp...TL071 and family being very common...you will see that it is chock full of diodes, caps and resistors and quite a few transistors. Now...a transistor will give you the same effect, high input, low output...do you really want the guitar signal going through all these extra components? Well...maybe you do...it will give a very cold solid state kind of sound perhaps (different opamps have different characteristics) however, a design like the tillman or fetzer uses a single transistor and a few components to keep it happy, to provide the same kind of effect but a warmer "tube like" distortion characteristic. This may be even more desirable. Really horses for courses I guess...and again depends on the application and what kind of effect you are trying to achieve. Personally, I don't mind opamps for some things and once you start wanting to add variable gain (by altering the feedback ratio) or tone controls or adding numerous stages (a TL072 is a dual opamp in the same size pack for instance and is often easier to work with than the single 071 for the same price even if you only use half of it!)...they also have their own bias circuitry inside that gets rid of pesky biasing trimpots and stuff...they do have a tendency to draw a bit more power, but then it is very little anyway so it hardly matters that much...with more complex circuitry that might have active tone controls (cut and boost) or overdrive (added diodes to produce clipping as in the tube screamer and such) or other processing...there is a lot to be said for opamp circuits. I am not following however the application that your question is asking...generally, you would buffer all of the pickups or signals A & B I suppose, either collectively or individually, or both (as in a mixer circuit) due to potential issues with mismatched impedances, control problems and loading issues. There can also be issues with "popping" when active circuits are switched in and out of a signal...so say you have two pickups and one is active, selecting the non active pickup may well generate a mini power surge that will be loud through a wall of marshalls!!! pete OK yeah let's say A and B are pickups. And lets say they both have voltage followers on their hot leads. And they are in parallel. Would the output of this circuit be simply A+B? Or would the two voltage followers affect each others' performance? oh, then consider the same circuit using transistors instead of opamps. Would the output be A+B? Hmmm I'm not trying to use them for any distortion, so "tubelike breakup" isnt important, but other than that, how would an opamp make a signal sound "cold"? .....Limited bandwidth? and by the way, I'm not just asking all this just for one specific application, it's mainly about a deeper understanding about how opamps work. I KNOW how opamps work, but to know and to understand are entirely different

dude did this website just bleep out the word that starts with a cr- and ends with a -azy?

that pulling cloth over the joint thing sounds cool... do i ask too many questions? it's only because i love guitar electronics!

What does all the cicuitry inside an opamp do to the sound that makes it any worse than transistors? I know that the impedance difference will cause one signal to be much more prominent, but what I am asking is: Does B affect the operation of the op amp? I was thinking that maybe since B is tied to the output, and therefore the inverting input, B would become obliterated by itself and there would be no trace of B in the final signal. Does that make sense? And also, does the impedance of B change how B affects the op amp operation?

I have read many places that vintage guitars had cloth-coated wires connecting the components. Does this DO anything differently than plastic coated wire? Or is is just for people who are **** about vintage replication and identification? One place said that cloth wires were individually shielded by the cotton. Isn't cotton nonconductive? I am confused. Answers?

An Op Amp Voltage Buffer, a.k.a. Voltage Follower, is when you connect the output of an op amp directly to the inverting input. The voltage at the noninverting input is copied directly to the output. But there is infinitely high input impedance and infinitely low output impedance. Google it for more info. So here's the Question: Say you've got a voltage source, "A", before the Voltage Follower. In parallel with all of that, you've got another voltage source, "B". How does B affect the operation of the voltage buffer? Would the 2 voltages just be added? Would the total output just be equal to B or A? Would B invade the inverting input and get saturated? I ask because I am considering using op amps in some active circuitry in my guitar.

yeah but to demo something yourself is so much more informative, ya know?

yeah when i test drove one, i didn't get to play it through an amp. How would you say they're different? brighter, warmer? midrangier? more/less attack?

Do you mean that the volume/tone knobs are not independent? That will happen, to where when you turn the tone down for one pickup, it effects the others. There are ways to wire around that. Is that what you're talking about? p.s. How many knobs are there on the guitar?

So you mean it's like just a "mid" control? My amp already has one of those. It's called "mid". Or "contour" it like a "Q" control for the mid knob?

My Mesa 5:50 combo amp has a single knob that is called "Contour". The manual and website says it "adds the power of a graphic EQ to your amp". That doesnt exactly tell me what it does. All I know is, my sound is better, thicker, ?heavier? when I have the contour knob all the way up, so I keep it that way. My amp already has a parametric EQ, so it's probably not a bass, mid, or treble knob, so...Can anyone tell me what the knob DOES?

These Taylor solidbody "3/4 size pickups"; are they just mini humbuckers? Is there anything different about them? The website said they were revolutionary, but they seem to be just mini humbuckers. Has anybody opened them up or found an article showing what's inside?

oh. sorry. i guess this forum is just for on board guitar electronics? i'll try that site

Anybody have a schematic for an EHX Micro POG? I can't find it anywhere. Does anybody know even where I could get it? I hate when I can't find schematics.