Basic electronic questions (again) buffer and impedance?

[Pierre]

I don't REALLY understand what a buffer does... Basically the way I see it, without a 3PDT (or DPDT without a LED), the signal still goes through the circuitry some. The buffer aims to reroute this signal or, boost it, or just stop it...? It's meant to drive long cables so I gather it IS some kind of boost?

Also... What is impedance? :icon_lol: I've been looking allover the place for a basic, clean, simple explanation but so far nothing but technical explanations which don't really help...
Just some simple basics would do, no need to dwelve into deep electronics. But all that would surely help me understand pedals a little better! Thanks guys!

 

[Vasshu the humanoid typhoon]

Re: Basic electronic questions (again) buffer and impedance?

Buffer makes the impedance go from high to low, so that it can travel without loosing highs and be more immune towards noise and statics.
Impedance is resistance broadly explained.

 

[Pierre]

Re: Basic electronic questions (again) buffer and impedance?

Ahhhh I see...So basically it makes the resistance higher so that it doesn't actually travel inside the circuit...? Or is it more complicated that that? Losing highs has go to do with the capacitance right?

 

[Artie]

Re: Basic electronic questions (again) buffer and impedance?

A buffer won't change the impedance unless its designed to do so. (WHich many are.) Mainly, a buffer is a current amp. That is, it has what we call "unity gain". It doesn't change the voltage, but is capable of supplying more current. Thus, a long line, or driving multiple inputs, won't load down the signal.

Impedance is simply resistance measured at some frequency above zero hz. Once you get above zero hz, (DC), reactance, inductance, capacitance, and all that stuff come into play. Thats why you'll often see "nominal" impedance. They measured something at just one frequency. For speakers, thats often 1k hz.

 

[Vasshu the humanoid typhoon]

Re: Basic electronic questions (again) buffer and impedance?

Hehe always count on Artie to do a reasonable explanation
Yep a buffer is an active unit, some uses discrete transistors, others use one outtake from an op-amp(we do)
So if you do not like the tone, you can find a transistor or another op-amp, and it will change the sound of the bypass, some buffers are made to hinge off the whole circuit, so no signal will pass, others just pass through and go through the buffer when it travels out.

 

[Pierre]

Re: Basic electronic questions (again) buffer and impedance?

So the LED is in the buffer stage and it's made to light only when there's voltage across the actual circuit?

And I'm guessing the kind we talk about when we assume a buffered pedal will help out with long cables is the second type, where it'd work even with the pedal is off?

I think I'll stop with the questions and try to do some more reading hehe... thanks guys! I tink I assumed a little too strongly that you can understand guitar pedal electronics well without knowing much about basic electronics first, but I was just entirely wrong :s

 

[nebucanazza]

Re: Basic electronic questions (again) buffer and impedance?

Also note that impedance of components like capacitors and inductors totally depends on the frequency. For example, a capacitor is an open circuit for DC( hence its use for DC blocking). If your input impedance is quite high compared to the output impedance of the preceding block, most of the signal will pass through. It follows the formula V = Vin. R2/(R1+R2). So if R2 = 1M and R1 = 100K, V = 0.91 Vin . The highs are the most affected by this. So when we have a pedal doesn't have high enough input impedance and it is loading the pickups, you see a drop in the signal level and rolling off in the high end.

Seriously, go to geofex.com and you get all your answers from the master himself

 

[RockStarNick]

Re: Basic electronic questions (again) buffer and impedance?

I forget who said it, but someone referred to a buffer as a device that takes the original guitar signal, and makes a low-impedence "copy" of the signal.

The quality of the buffer is determined by how faithful of a "copy" it makes.

I just bought myself an Axess electronics buffer unit. size of an MXR, and is supposed to sound incredible, and help out alot if you put it first in your chain of effects.

I could always hear some sort of difference in the boss buffers. Never really like them.

 

[Pierre]

Re: Basic electronic questions (again) buffer and impedance?

I got a lot of texts from various forums and I think I quite understand now! Thanks a lot guys! You surely helped!

 

[nebucanazza]

Re: Basic electronic questions (again) buffer and impedance?

Yup..told you..nobody explains it like RG does

 

[Vasshu the humanoid typhoon]

Re: Basic electronic questions (again) buffer and impedance?

Yeah he is cool!!
But I am never going to like their TB fetish