can someone xplain..line vs. mic input.. balanced vs. unbalanced?

justmarvin

justmarvin

Well-known member
Would someone explain these so I have a better understanding?

I heard you usually just leave the audio stuff to "mic input" but what is line input for anyway? When would you switch to line input?

Also, i've heard the terms such as this is a "balanced" mic or cable... etc. Can someone explain what balanced and unbalanced is in reference to mics, cables, and plugs?

Thanks! You guys are great helping other learn this stuff :)

Take care,

JM
 
Sorry guys, i'm new to this sound stuff..

Can someone also explain Condenser...vs... Dynamic mics? What's the difference, etc.
 
Here's some quick & dirty on it:

-A mic input accepts signals from microphones or other devices that output at "mic level", which is very, very low. So those inputs include a preamp, which boosts the mic level by roughly 4 to 10 times (depending on impedance/operating level, as discussed below), so it can be recorded at a suitable level.

-A line input is a signal that is already at the higher level that a mic preamp would boost a mic to, such as a CD player, iPod (line out, not headphone out, which is much hotter), camcorder output etc.

-A mic plugged into a line input will be almost inaudible. Something like a CD player plugged into a mic input will distort horribly. That's why the two level standards exist.

-High and low impedance are match-up factors as well. Without going too deep, you simply need to use matching impedance devices together. Plug a Hi-Z mic (Z = impedance) into a Hi-Z input and so on.

-Both line and mic inputs can be either Hi or Lo-Z. It's best to check the specs on each device, but generally the following applies:

Hi-Z line level devices are usually connected by RCA or 1/4" mono plugs, and operate at a -10 DBv level. Hi-Z mics usually also use 1/4" plugs and operate at about -20DBv level (as do most electronic keyboards and electric guitars).

Lo-Z line level devices usually use XLR plugs and operate at +4 DBm level. Some use stereo 1/4" plugs. Lo-Z mics almost always use XLR plugs and operate at about -50 DBm level.

You can see form the above that basically, you can't intermix line/mic or Hi-z/Lo-Z devices. There are notable exceptions, particularly when connecting Hi-Z line outs (*when properly rewired*) into Lo-Z line ins and vice-versa, but otherwise the former is the rule.

Hope this helps
 
Last edited:
The only thing I would add is that mic levels are typically measured in millionths of a volt and line levels range from roughly 1/10 to a couple of volts so the difference can be a lot greater than implied above.
 
Right. There are large differences in output levels between various devices within a category, so my descriptions were general in nature.
 
Noiz2 said:
The only thing I would add is that mic levels are typically measured in millionths of a volt and line levels range from roughly 1/10 to a couple of volts so the difference can be a lot greater than implied above.
Click to expand...

Sorry to be picky, but most mic voltages are in millivolts which is 1/1000th, not a millionth. Millionths would be microvolts.
 
justmarvin said:
Sorry guys, i'm new to this sound stuff..

Can someone also explain Condenser...vs... Dynamic mics? What's the difference, etc.
Click to expand...
Dynamic and condensor mics use different methods of transducing vibrations in the air into electrical signals.

A dynamic mic's diaphragm is attached to a coil. Air pressure moves the coil back and forth through a permanent magnet, which induces an electrical signal.

A condensor mic consists of a diaphragm positioned very close to a metal backplate, which is charged by an external voltage. This arrangement forms a variable capacitor, in which the capacitance changes reflect changes in sound pressure level. Condensor mics are sometimes referred to as "capacitor" mics.

In more practical terms, condensor mics tend to be far more sensitive, and to have lower self-noise than dynamic mics. Dynamic mics, on the other hand, tend to be much more rugged and accept much higher sound pressure levels. Condensors mics require an external voltage to charge the capacitor (such as 48V phantom power), whereas only a few dynamic mics require external voltage. Most of the microphones used in production sound recording are condensor mics.
 
Although it should also be pointed out that Electro Voice RE-20s and Shure SM7s, both dynamic mics, are hugely popular in studio use for all kinds of video, TV and radio productions.
 
Steve House said:
Sorry to be picky, but most mic voltages are in millivolts which is 1/1000th, not a millionth. Millionths would be microvolts.
Click to expand...

"In terms of voltage, the boost is from levels measured in micro-volts (millionths of a volt) to between 1/10 volt and 2 volts."
section 11.2 pg 152 Sound Reinforcement Handbook

Ted, I wasn't criticizing just emphasizing. There are some very hot mics out there that can close the gap considerably.
 
justmarvin said:
Would someone explain these so I have a better understanding?

I heard you usually just leave the audio stuff to "mic input" but what is line input for anyway? When would you switch to line input?

Also, i've heard the terms such as this is a "balanced" mic or cable... etc. Can someone explain what balanced and unbalanced is in reference to mics, cables, and plugs?

Thanks! You guys are great helping other learn this stuff :)

Take care,

JM
Click to expand...

All of the information in this thread is very good, these guys know of what they speak but if you are looking for something more basic in understanding these concepts and how they will relate to you actually buying sound gear, give this a try http://www.kenstone.net/fcp_homepage/location_sound.html

Good luck,

Dan
 
You must log in or register to reply here.
Back
Top