View Single Post
  #2  
Old 2011-09-30, 16:00
Pr0az's Avatar
Pr0az Pr0az is offline
Post-whore
 
Join Date: Oct 2006
Posts: 1,923
Quote:
Originally Posted by Dystopia
1) I need to know the expected output frequency... and yes, I have looked at tables (E=84.5Hz, A=110Hz), but anything you guys can tell me that will help me recreate the input signal to the output signal that is recorded. I know that the sampling frequency must be double the frequency I wish to output to human ears, but that doesn't mean that a 110 Hz sine wave should be sampled at 220 Hz, that would sound too robotic.

2) So that I can accomplish 1, how do I properly measure the signal of my guitar on an OSCILLOSCOPE?
I know that the coils of the magnetic pick-ups convert the energy of the vibrating strings into an intelligence signal to be carried over to amp, but 1/4"TRS (tip, ring, sleeve).. I look at them, and wonder: Where does the power come from? I don't think I can just plug in a cord, measure the other end of it, play some notes and see the wave-form I want.

I've asked my teachers about step 2 and I am told I need to measure it coming from the Amp, which leaves me wondering how does the signal get all the way to the amp without any power pressing it? I mean I'm pretty sure it's (Ring=Right input/ Tip=Left input/ Sleeve=ground). IS THERE power connected to it? Guitar battery?



You have almost confused me with this post. With two years under your belt for an electrical degree, you lack some basic knowledge.

Understand most guitars are completely passive(A good example this is a battery powered small tuner, i can take my guitar hook up the tuner and works just fine without an amp, there is no need for an amp the small signal being sent is enough for my tuner to work). A guitar amp amplifies the guitar by a section of the amp called the Preamp(One of a few steps to amplify but this is the very first). See Magnets and coils which are the basics behind pickups produce current when strings are plucked on the electric guitar(Magnetic Wave -> Electric Field-> Current Flows through coils), this goes way back look up "Faraday's Law of Induction".

See the reason an amp is needed to begin with is to "AMPLIFY" the sound already made by the existing low voltage that is produced by the string+pickup(coils+magnet(s)).

Now do understand some pickups use batteries like active pickups and crap but the basic "passive" pickup does not.

I have some good ebooks on this subject which I'll be glad to offer you. I only ran through them ones or twice, because shit I already had a few books on my shelf that taught me what I needed to know. I've got some .pdfs that show you the design guitar pedals such as loopers, distortion, and etc as well. They are not the best schematics in the world, but could offer you a helping hand in the design of your project.

You may have come across a project in which you must dedicate every hour for the next 8 weeks to complete. From what I'm reading i cant understand is this thing going to be analog or digital (solid state)? You have a challenge here man between signal processing and hardware design. See you have mentioned there are no means of "no guitar-electronic engineering processes" you must take what you have learned and apply this to the current project and also do in depth research on it. We are not searching for "guitar-electronic engineering processes" but for signal processing alone be it of sound or images(both are "data" one in the same, we as designers must tell the mechanism what to do with it because it has no clue to what makes an image an image or a sound byte a sound byte to it an apple is an orange and an orange is an apple unless other wise coded or wired to tell the difference).

"I've asked my teachers about step 2 and I am told I need to measure it coming from the Amp", if you measure it from the amp or the guitar alone your going to get the same Frequency just a different Amplitude. You'll be dealing with Hertz(hz). Shit you can even measure an acoustic guitar and get the same results as long as both of the tunings are the same, with again the only difference being the amplitude. Hell, you could take a piece of plywood tap some nails in it, get a pack of guitar strings, wrap them around grab a tuner and tune to (EBGDAE) and still get the same damn frequency. Here's a schematic if need be http://i136.photobucket.com/albums/...z/schematic.png
__________________
“Remember to live, eat, sleep and breathe music for the mind, play from your heart and never be swayed by the current trends.” ~Rusty Cooley
Reply With Quote