Want some input about inputs? They might appear to do the same thing but a microphone input and line in input are different.
The most basic explanation I can give is that a microphone input usually provides a very low signal level. This low signal is mono. But with a line in input, you get a much higher input level. Thus higher is stereo.
For a line in input, it runs around 10Kohm impedance. By contrast, those mono microphone inputs are at 600-1Kohm impedance. Where would these best work? For line in audio input, you’d want to connect music players. Think MP3 or CD players. Even an old-school tape player would work.
It can’t be used for a mic input though because it would barely be heard. Microphone inputs need around -5 mv since CD players and MP3 players produce an output to the tune (pun intended) of about 100+ mv. That means the line in input is the best option.
But let’s address the subject of turntables and record players hear since vinyl is making such an epic (and well-deserved) comeback. These items have tailored frequency responses to suit them. Yet, they have input sensitivities that are quite similar to microphone inputs at 5 mv.
However, don’t think you can get away with plugging a microphone into this input. Yes, it would work. You’d hear it, but the frequency would be all wrong and create quite a discordant situation.
So now that I’ve touched upon that briefly, keep reading and I’ll further detail about line in and microphone inputs.
What exactly is a line level?
Your line level signal is just about equal to one volt. To put it another way, it’s roughly 1,000 times the strength of a microphone level signal. As you may have already guessed, you don’t use the same input for these.
With this signal, it runs from your pre-amp and then on to the amplifier that gives your speakers juice. With line levels, there are 2 common types with dBV and dBu, decibel measurements related to voltage:
1. -10dBV – This is what you see with consumer electronic products like your DVD player, MP3 player, CD player, and the like.
2. +4 dBu – This is what professionals use for their equipment. Things like mixing decks and signal processing gear use this standard of line levels.
There are other types of audio signals too. Instrument levels are like microphone level signals. They need preamps to get them to the line level. Speaker levels are post-amp signals. They require even higher levels of voltage plus speaker cables for proper transfer of signal.
What is a microphone-level?
Now let’s move onto microphone level, or mic-level. This signal speaks of the voltage that a microphone creates once it picks up sound. This is usually only a few thousandths of a single volt. So the voltage varies when the sound level and distance change.
With the different types of audio signals, this level is the weakest one. If you want to get it to line level, you need a preamp. Generally, microphone levels are between -60 and -40 dBu. Mic-level inputs are usually female XLR connectors while a line level input is usually in the form of an RCA jack, a phone jack (one quarter inch), or even a 3.5 mm phone jack.
Keep in mind that your connector type isn’t the same as signal levels. Generally, they work as female or jacks though it’s not always the case. In other words, don’t assume that a signal level will be a certain way based on the type of connector. Fortunately, in the case of audio interfaces, these things are usually clearly labeled to make it a breeze.
Of course, you’ll need to boost those mic levels and that’s where several different devices come into play. Among the most popular are mixers like the karaoke mixers you see on parties. These bad boys combine several signals together to join them as a singular output. Preamps and mic-to-line amplifiers also do this though. You will see them as single-channel or multi-channel.
The fascinating thing is how you can raise those mic levels to line levels, so keep reading and I’ll get into that below.
How mic levels are raised to line levels
Let’s take a look at your audio equipment. If you find mic level inputs on there, they will be joined by a preamp to boost the signal. Try plugging a mic into that mic input on your mixing deck. Your device will be anticipating a mic level signal.
Then you use that built-in preamp to bump that signal up so it’s now line level. Simply adjust the gain control for your input’s preamp.
What about your guitar? Ready to rock out? You need to plug an instrument into an instrument level input on there. It adjusts to line level with the preamp. That all seems pretty basic, yet getting these mic levels to line levels is important for the right sound, just like tuning your guitar is. So, should you mix them up, you’ll likely know it by the distortion.
Remember, there are different signals that come from microphones, outboard equipment, and instruments. You need to stick to the proper signal type for the inputs that are designed for that specific signal with your audio interface.
Matching is something I think all of us learned in kindergarten. Though rudimentary, when you mismatch the signal levels, you get that distortion. Mic level is the lowest while instrument level is a bit of middle ground. Then there’s line level as I described further above.
With your audio equipment, if you have mic level inputs or instrument level inputs, they will be joined by a preamp for boosting the signal. Plug your mic into the mic input and it anticipates a mic level signal. Your preamp then boosts that signal to get it up to line. The same is true with instruments in the proper input.
But not every piece of equipment has the inputs you want. So if you want to connect your instrument or a line level signal and there are only mic level inputs, you have to get a DI box which will convert them to the right signal. From there, take the preamp from the mic input and raise your signal for optimum control.
Still confused? Follow the steps below to get the right levels!
How to Connect Line Level Gear to a Mic Input
Since your mic puts out a significantly lower voltage signal than a line level, if you plug in something else besides one into your equipment, you’re likely to overload it. That results in distortion. And when distortion happens, you need to know that you can’t change those input characteristics of your device.
So, you’re stuck for lowering the output of the sending device. But there’s more than one way to skin a cat here, or get the desired result:
- Turn down the output of your device
- Add in a signal path
As the first option is easiest, let’s get into that first.
All you need to do in this scenario, which should be the first thing you attempt, is to turn down the output of that sending device. The distortion of your receiving device should cease. While it’s usually quite effective and costs nothing for you to do, it may also compromise the signal to your noise ratio.
So if that happens, then you’ll have to look to your next option which is adding in a signal path. You can either buy or build a pad to lower the voltage of that incoming signal. If you’re not in the mood to play MacGyver and build it yourself, you can buy one, though building it yourself is more cost-effective.
Plus, when you build it yourself, you can fully customize it. You’ll be able to control the gain reduction amount and the connectors so you can configure it to your set-up. Unless you’re a qualified technician though, you may want to leave that to the pros. Those handy at soldering may stand a chance though it will take a great deal of research on YouTube and in books about electronics.
Hence, most people go for buying a pad and get on with their lives. A solid choice for sure, though costly. Still, it’s a wise investment you’ll be using for years.
Mic in or line in: which one should you plug in a microphone?
When it comes to your input and your mic, you might be wondering what you should choose with these 2 inputs. As I mentioned earlier, the biggest difference between them is the intensity of the signal, or signal level.
Your microphone signal is the weakest in voltage, but that signal varies when the distance of speaking changes. You can increase the intensity of the signal when you bring it to line-level. Remember, that increases significantly when you do.
Knowing what device and the jack you use to plug it in helps. With mic signals that run through your preamp, any mic-to-line amps, or a mixer, you can create that line signal. Using an analog mic to connect to your computer or a speaker with a line in jack, you’ll need one of those 3 items.
Plug that mic into the mix jack and you should be in business. Just know that when you don’t connect it right, you may be in for some damage to the device or run into poor audio quality.
What if you plugged a microphone right into a line level input? In that instance, you will barely hear a thing. That mic signal is so weak that your line input won’t be able to detect it. Don’t make the mistake of plugging a line level source like your mixer to the mic level input. It will create a loud, unpleasant distortion because the signal is too strong.
As I covered with inputs and connectors, the general rules apply though don’t just assume that those levels will match because the connectors fit. Most inputs are clearly marked to prevent getting it wrong, not just for novices but for catching your attention before you make a critical mistake.
When there is only that mic input, you have to reduce the voltage first if you want to connect a device with a line level up to it. Investing in a DI box is ideal for this. You have options with cable versions that come with resistors built in too.
Don’t forget that wireless receivers will have different output levels from one another, even in the same brand line. It’s important to read up on your user guide to find out that output signal level as there can be as much as 20 dB variance between each receiver.
In short, the signals and voltages vary between microphone inputs and line in inputs. Connecting your device properly is the best way to keep from damaging your equipment or at the very least causing everyone within earshot to cringe from the distortion. While these things are generally labeled to prevent confusion, confusion does happen.
I recommend reading your product manuals and having the right inputs for your devices. If something doesn’t match up, it’s easy enough to get a DI box that will make short work of it all.