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Whether one is producing music, podcasts, game sounds, or film sound effects, Digital Audio Principles provides the tips and techniques that will make the project a success. Author Dave Schroeder explains the basics of digital audio production techniques and covers the essential hardware and software. He also discusses sound theory, frequency response, the range of human hearing, and dynamic range.
Okay, so let's take a tour of a stand-alone pre-amplifier. Here we have a two channel tube pre-amplifier. It's got lots of options, there're some knobs and adjustments. Let's start with the back and look at the inputs and the outputs. So first, we have the inputs. These are combo jacks that will accept either a microphone cable, an XLR cable, or a quarter inch jack into the center there. These are cool designs that save a lot of space and interfaces. You'll find them on a lot of preamps now, and a lot of audio interfaces that connect your computer.
So I'm actually going to connect my iPod here into Input number 2, which normally wouldn't be connecting to a preamp, you'll be connecting a microphone or something else that needs boosting. Most often a microphone, but for this lesson we're going to show that. Now we've got the outputs, channel outputs, these two will go for channel 2, these go for channel 1. Balanced output and an unbalanced output, and we can select based on how we want to work, which ones to use. I'm going to take a balanced output of channel 2 and feed this into our recorder.
So now let's look at what we have on the front. I'll just go along the buttons. Each channel is the same. It's just the same thing two times. I'm going to start over here. We have the 48 volt phantom power button, which as we mentioned is what condenser microphones generally need. By pushing this in, it feeds 48 volts out through the microphone, input on the back, to your condenser microphone. If you're using a condenser, think it's all working, but you're not getting you sound. Try the 48V button with the phantom power. Next we've the phase button, which is designated by this little circle with those slash through it.
By pushing that in, it will change the signal coming through this channel only 180 degrees out of phase. This is helpful if you're having phasing issues with the way your microphones are set up. Also there's a pad. On this I think it's about 10DB. By pushing that button in and out, these are cool, because they are light up, by the way. By pushing that button in and out, you'll reduce the signal completely by about 10DB no matter what. By pushing that it cuts the pickup of 80Hz frequencies.
Then we have a gain knob, which is the preamp adjustment. So as we're sending signal, we can turn this up, which I'll send a little bit right now which I'll start to hear here. There we go, so now we have a single, we can see in our meter. We can use this gain knob basically to increase the input level of our input so that we can get a good signal to the recorder. Now this is an analog meter, that's not digital, so zero DB is where it kind of goes from Black to Red.
With analog it's okay to go pass that zero point and really you just want to trust your ears. Obviously, it's really spiking over there. That's a little too much as it just gets pegged against the wall like that. Sorry if that's distorted. Anyway, right around there you can go above and below, and actually a little bit of Red is good. With analog the trick is to really trust your ears. If it sounds good, it is good. Also on this, because it's a 2 pre-amplifier, we have an option of how much of the two we want to use when it's turned all the way off. I'm not using any of the two, but I can turn that up, and that basically sends the signal through an audio tube, which is this little fellow.
Which is a device that people claim really warms up the sound of an audio signal. So I can use as much of that as I want. So we're done with the song. But if I crank that all the way up, I can actually get distortion on it. We'll see if we can--if it actually distorts, it might not. So you can use it for a distortion effect on vocals, but really you just use a little bit to kind of warm things up. And we'll talk a little bit about the analog and tube and digital and all that stuff in a different section, but anyway that's the general principle and the general set of features that we're going to have when you are dealing with the stand-alone preamp.
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