How does a guitars signal get amplified? And A TS Poll.

[ibanezts808]

I have Two related questions:

1.  How is a guitars signal amplified?

2.  How far can the signal be amplified before clipping? (I'm sure this is based upon transistors and what not, so I'm asking this in generic terms.)


Thanks Guys.  Have a great day!  

[mlabbee]

The answer to question 2 is - as much as you want.  It is entirely dependent on the amount of power available to the amplifier . . . that's why you can get your ears blown out by a nice clean acoustic guitar at a big concert.

The answer to 1 is a bit more complicated - someone posted an explanation recently using a water analogy, which was pretty good.  Basically, the signal coming out of your guitar is a current with a varying votage - the voltage goes positive and negative over time, thus creating the sine wave looking thing you normally see on scopes.  The variation in voltage is, however, very, very low (millivolts?  anyone?).  In theory, this signal could be directed straight into a speaker and you'd be able to hear it, but the voltage is so low, it can't really move something as heavy as a speaker enough for you to be able to really hear anything.  So you need to amplify the signal - create a signal having the exact same variation as the guitar singal, but with a much higher voltage differnential between the peaks and valleys - on the order of several volts.

What transistors (and op amps) do is basically look at the incoming signal variation and modulate a much higher power signal in the same way - so when there's a peak in the guitar signal, the amp lets the voltage on the high power signal go up, in the same proportion as the guitar signal. When the guitar signal goes negative, same thing - basically, the amp just makes a bigger copy of the input signal.  Since no amp is perfect, there are errors in the copy - also known as distortion.

If you try to amplify the signal so big that there isn't enough voltage available in the high power signal, it goes up as high as it can and then just flattens out at the max - and you have clipping - i.e., the top part of that sine wave is "clipped off."

Hope that helps - this is the kind of thing that's easier to explain in person with a pen and paper.

[bwanasonic]

Any good basics electronics book will answer your first question. You can search the forum here for some recommendations. You pretty much answered the second question yourself- it is completely device/circuit dependent. There is no *generic* limit. As for the poll question: I have used a TS9 for over 20 years, but have never understood the discussion of minute variations in TS tone as if it were a 20 year old vintage wine...


Kerry M

[mlabbee]

Dude!?!?!?  What are you talking about?  Don't you know that an original 1982 4558 chip, produced in an odd month with exactly 4 microns of oxidation on the pins has the BEST tone ever?!?!?!?   :twisted:

[David]

Dude!?!?!?  What are you talking about?  Don't you know that an original 1982 4558 chip, produced in an odd month with exactly 4 microns of oxidation on the pins has the BEST tone ever?!?!?!?   :twisted:

Whachoo tawkin' bout, Willis?  It has to be 3.141592 microns of oxidation, and the oxidation has to have occurred in Texas bars.   :twisted:

[Hal]

i think the easiest amplefier to think about is the ideal tube triode.  In this you have a huge voltage (and therefore available current) from the anode to cathode.  However, the tiny voltage applied to the grid is able to control this huge current.  Thats why they call it a "valve." - the origional signal its self isn't amplefied, you're making a larger copy of it, with the origional signal controlling the copy creation.

Clipping occurs when you try to amplefy it too much.  When all possible current is flowing from the anode to the cathode, changing the grid voltage won't make a differance.  The tube is said to have reached its saturation point.  This clips the signal.

[bwanasonic]

i think the easiest amplefier to think about is the ideal tube triode.  In this you have a huge voltage (and therefore available current) from the anode to cathode.  However, the tiny voltage applied to the grid is able to control this huge current.  Thats why they call it a "valve." - the origional signal its self isn't amplefied, you're making a larger copy of it, with the origional signal controlling the copy creation.

Very good! I often have in my head the idea of making shadows with your hands in front of a light when thinking of the way a tube works. Or maybe even a movie projector. The little aperture where the film passes thru controls the flow of the very bright light.

Kerry M