How Guitar Amps Work: Explained

[Sniperman724]

How exactly do guitar amps work and why can't I just plug my guitar into my computer and start playing with the computer speakers instead? I am just curious

 

[vk6kro]

How exactly do guitar amps work and why can't I just plug my guitar into my computer and start playing with the computer speakers instead? I am just curious

You could do that although the normal amplifiers in computers only produce a watt or so. This sounds pretty loud in a quiet room but probably wouldn't impress anyone at a concert.

So, it is mainly the power out that makes a difference. I understand that some guitar amps also have ways of deliberately introducing distortion.

 

[schip666!]

How do amplifiers work, or what do they do?

What they do is increase the amplitude of the pickup signal. Microphones and pickups produce something in the region of 10 milli-volts at a very low current, which is not enough "juice" to make an audible sound come out of a regular speaker. You can get very sensitive earphones (or used to be able to get, back in the day when crystal radios were popular) which might allow you to hear the pickup signal without further amplification, but they would not be practical for a stadium concert...

Most computer audio inputs have enough gain to handle a microphone, so you should be able to plug in your guitar and hear something. Have you tried?

How amplifiers work without a lot of physics is pretty much a tautology. They increase the amplitude of signals by having some kind of component that has an input, something that has gain, and an output -- they amplify. The gain component can be a transistor or a tube, where the input gets a small amount of power and uses it to control a larger amount of power which comes from a battery or wall outlet. Poke around wiki and such for info on transistors and tubes for some better explanations...

 

[Sniperman724]

Most computer audio inputs have enough gain to handle a microphone, so you should be able to plug in your guitar and hear something. Have you tried?

Yea, I have actually tried to plug my guitar directly into my computer microphone jack because i wanted to see if it was a better way to record what I can play instead of placing my headset microphone in front of my amp and recording that way.

 

[turbo]

Yea, I have actually tried to plug my guitar directly into my computer microphone jack because i wanted to see if it was a better way to record what I can play instead of placing my headset microphone in front of my amp and recording that way.

Guitar amps color the sound in ways that no sound-card can replicate. I prefer tube amps, but there are some artists (David Hidalgo and BB King come to mind) that can slay you with solid-state amps. Use an amp, and learn how to mic the speaker(s) for interesting results.

I have two vintage Fender Vibro-Champs and a more modern custom tube amp. I'd never give up the little ones.

 

[schip666!]

Yea, I have actually tried to plug my guitar directly into my computer microphone jack because i wanted to see if it was a better way to record what I can play instead of placing my headset microphone in front of my amp and recording that way.

And you got nada? Not having a regular electric guitar I can't try it, but I'm a bit surprised at that. You may have used a "line level" input (like you would connect a CD player or such to). Are you sure you used the mic input? But the advice about desirable distortion from a guitar amp should be heeded. If your amp has a headphone or remote speaker output you should be able to connect that to the line input.

 

[vk6kro]

The microphone input may not be selected in the computer.

If you are using Windows, go to Control panel, sounds and audio devices, then audio, then sound recording.

This may vary a bit with your sound card, but you should see a row of audio gain controls with "enable" or "mute" choices at the bottom.
Select the microphone one and turn the volume up full.

The microphone input on most computer sound cards is mono, so if you want stereo, you need to amplify the signal externally (with a pre amp) and feed it into the line input of your computer.

 

[mugaliens]

Most computer audio inputs have enough gain to handle a microphone, so you should be able to plug in your guitar and hear something. Have you tried?

Depending on the impedance of a guitar's pickup circuit, that might blow something in the computer's mic input.

I wouldn't try it!

Most electric guitar pickups are magnetic, wherein the vibration of the ferrous content of the wired strings varies the magnetic reluctance in the circuit created by the wire-wrapped permanent magnet of the pickup.

Given the output voltage ranging between 100 mV and over 1 V, this is in the same range as what's commonly referred to as "line level." It's around 1 V, and the standard is employed in nearly all A/V equipment in use today, through the familar RCA audio jack (usually red and white). A quick trip to your local Radio Shack will probably yield a y-cord with a standard 1/4" plug on one said and a single or dual RCA plugs on the other which you could plug into the back of your stereo's inputs with decent results. In fact, I made just such a y-cord (shielded) to record a neighbor's guitar licks back in college.

I had to turn up the volume (actually, the tape deck's input levels) a bit more than usual to achieve proper Vu, and unlike a guitar amp, the stereo input does not correct for the fequency weighting which normally eminates from guitars.

I would NOT plug it into your computer's microphone jack, or a stereo's phono inputs (for record players) however, as they're much more sensitive to voltage, and may overpower your unit.

 

[chaoseverlasting]

I've done it without screweing anything up and I've been able to get a clear signal. Of course, it may not work in your case with your setup, I would listen to what mugaliens has to say. I didnt particularly care about that particular pc of mine.

 

[elbeasto]

You will run into a few problems if you are doing everything raw like you are saying in your original post. I do some home recording myself and I started exactly where you are at now.

The reason you are not hearing anything is because of your playback options. The first thing you will need to do is make it so that you can "hear" your mic through your computer speakers. By default the mic is muted through your speakers because no one wants to hear themselves while talking on vent/teamspeak etc.

Secondly, once you hear your guitar through your speakers you will find you have about a 1-2 second delay between your strum and when the sound actually comes out if you have a stock sound card. It is super annoying and painful for playing live with a song on your computer. If all you are doing is recording and not using your speakers for live playback, you will be fine. But if you want live playback you will need something extra if your sound card tries to buffer too much.

If you find that you do have the delay you can go 1 of 2 routes. Get a better sound card or get an pedal with a built in interface. I recommend the pedal with interface but it will generally cost at least 100$ for something basic I think.

I am about to purchase a line 6 pod hd300 or 500. It will act as the effects and interface so that I can play directly into my computer with no delay and it acts as an amp too giving it more power through your speakers.

Hope this helps.

 

[Sniperman724]

Thank you, that actually helps a little bit, I will not try to hook my guitar up to the microphone jack on my computer again, and as for the recording quality of my current set up( the headset microphone sitting next to the amp while i play the guitar) actually works pretty well, the sound is very clear, but there is just a little back ground noise, i.e me typing and moving around before and after I play, but that could be edited out with any video editing program.