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  #1  
Old 11-21-2009, 11:33 PM
guitarlix guitarlix is offline
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Mic Level vs Line level vs Instrument Level

What's the difference?
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Old 11-22-2009, 07:15 AM
GuitarsFromMars GuitarsFromMars is offline
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The amount of voltage sensitivity in each input.
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Old 11-22-2009, 11:17 AM
ToddK ToddK is offline
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Quote:
Originally Posted by GuitarsFromMars View Post
The amount of voltage sensitivity in each input.
Well that clears that up.
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  #4  
Old 11-22-2009, 12:11 PM
LSchefman LSchefman is offline
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Line level is decibels across a standard voltage. It's often expressed as decibel volts (dBv) or decibels unloaded (dBu). Each of these has its own reference voltage. But in any event, whether you're basing it on +4dBv (so called pro standard) or -10dBu (so called consumer standard), you're talking about a lot more level than mic level or instrument level.

There is no standard for instrument level. For example, guitars and keyboards are not equal level instrument outputs, yet either can go through an amp, for instance. But instrument level's usually somewhere between mic and line level, and to go true line level you usually need an active direct box of some kind. To go mic level, you can use an active or passive direct box.

Microphones don't put out much voltage, so the signal is the lowest of the three, and needs to be raised quite a bit to reach line level. Remember, the mic is a very small diaphragm moving against a coil, a charged backplate, or between magnets. Not much output. So mic preamps do the raising of the signal level, hence, "pre-amplification". Different mics have different output levels, there isn't a true standard. A condenser mic, for example, has an output so tiny that it needs a built in active preamplifier that raises the level enough to reach typical mic level! This is why you have such things as tube mics, for that preamplification.

Hope this explanation helps a little!
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Old 11-22-2009, 02:50 PM
Gretschman Gretschman is offline
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Thanks

Quote:
Originally Posted by LSchefman View Post
Line level is decibels across a standard voltage. It's often expressed as decibel volts (dBv) or decibels unloaded (dBu). Each of these has its own reference voltage. But in any event, whether you're basing it on +4dBv (so called pro standard) or -10dBu (so called consumer standard), you're talking about a lot more level than mic level or instrument level.

There is no standard for instrument level. For example, guitars and keyboards are not equal level instrument outputs, yet either can go through an amp, for instance. But instrument level's usually somewhere between mic and line level, and to go true line level you usually need an active direct box of some kind. To go mic level, you can use an active or passive direct box.

Microphones don't put out much voltage, so the signal is the lowest of the three, and needs to be raised quite a bit to reach line level. Remember, the mic is a very small diaphragm moving against a coil, a charged backplate, or between magnets. Not much output. So mic preamps do the raising of the signal level, hence, "pre-amplification". Different mics have different output levels, there isn't a true standard. A condenser mic, for example, has an output so tiny that it needs a built in active preamplifier that raises the level enough to reach typical mic level! This is why you have such things as tube mics, for that preamplification.

Hope this explanation helps a little!
Thanks , nice explanation
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  #6  
Old 11-22-2009, 03:51 PM
MichaelK MichaelK is offline
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Quote:
Originally Posted by LSchefman View Post
...basing it on +4dBv (so called pro standard) or -10dBu (so called consumer standard), you're talking about a lot more level than mic level or instrument level.

There is no standard for instrument level. For example, guitars and keyboards are not equal level instrument outputs, yet either can go through an amp, for instance.
Les is right. Practically speaking, some keyboards or instruments with active pickups might be fine going into a -10 dBV line input without needing a DI.
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  #7  
Old 11-22-2009, 09:12 PM
LSchefman LSchefman is offline
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>>Les is right. Practically speaking, some keyboards or instruments with active pickups might be fine going into a -10 dBV line input without needing a DI.<<

Yes, I should have mentioned that; I even used to be able to run synths into my old +4dBv analog console's line inputs, because I could boost the input levels with the input level pot.

But for lowest noise floor it was often necessary to run them into a -10/+4 level converter, something you rarely see any more. They're still made by Aphex I think. I have one that I keep as sort of a "swiss army knife" product, even though I only need it rarely in this day of "in the box" synths.
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Old 11-22-2009, 11:30 PM
jmoose jmoose is offline
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Just to add two points of clarification to an otherwise great explanation;


Quote:
Originally Posted by LSchefman View Post
There is no standard for instrument level. For example, guitars and keyboards are not equal level instrument outputs, yet either can go through an amp, for instance. But instrument level's usually somewhere between mic and line level, and to go true line level you usually need an active direct box of some kind.
Usually "instrument" level is below -10dB line level. Typical guitar signal might be -30 or so... which puts it 34dB below a +4 line level signal. So if arranged from lowest level to highest it would be mic; instrument; line -10; line +4.

Just to add another small niggle, there is no "standard" for mic level either. (actually, theres no standard other then how they're measured!) Some modern condenser mics, like the TLM103 & some of the Blue offerings have an output so high, that if using them on drums or something loud all they need is phantom power w/o a mic pre to be at "line" level. You can plug 'em right into a compressor!

Minor point though... more often then not, mic level is lower then anything else.

The other VERY notable difference between all of these is impedance.

Instruments are usually 10k ohms; mic level 600 ohms & line about 1000 ohms. That's one of the reasons that if you plug a guitar right into a mixer it sounds crappy... the impedance mismatch.
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