H
homerecor
Lost in the Fog
Labels for input jacks can be confusing. What does Mic/Line/Inst mean?
These refer to the relative strength of an incoming signal in terms of dB level (volume). Average levels from different devices, (guitars, mics, CD players, etc.) can vary from -60dB to +20dB. This might not look like much in numerical values but it sure is a great deal in volume level. The ideal level of all incoming audio signals for recording would be at or about +4dB. Since so many different devices vary so widely this is an unrealistic expectation. We need a few different input types to accommodate those different levels. Common names are used on input jack labels but these can still be confusing or misleading if you don’t understand the whole “Big Picture”.
Why not just use one type?
It would seem at first glance that the industry lacks standardization for input levels. The pro audio industry does indeed have input standards. Consumer grade electronics have their standards too. We just tend to mix the standards from those different industries together. Most consumer grade audio products use -10dB and most pro audio gear uses +4dB. We audio engineers, D.J.s, soundmen, and hobbyist are the ones who mix and match different types of gear for different reasons. When you start mixing apples and oranges together, you just need to learn what works well and what does not.
If you plug a low level item into a device that expects a higher level, a lot of gain boost must be used to make up for the missing volume. In effect you end up boosting lots of noise along with the signal. This is called raising the noise floor. In a recording situation, this boosted noise may not be tolerable. Having inputs properly matched will work much better. The receiving input would be much more sensitive to the dynamics of the incoming signal and background noise could be left at a minimum.
To make matters even worse, most dynamic microphones fall very short for signal strength. They only average around -50dB. They almost always require some sort of boost in signal such as using a pre-amp. Dedicated preamps are better at boosting signal volume without boosting noise. Some equipment (like mixers) have preamps built in and are prepared to accommodate weak signals. These include some sort of input level control labeled as GAIN, TRIM, PRE, LEVEL or BOOST. These types of input jacks are usually XLR and are labeled “Mic”. These expect to see a balanced signal which most all modern mics do provide.
Guitars and basses tend to have a nominal level of -30dB but can vary greatly due to different pickup types. Some equipment has input jacks for this level. They would be called “Inst” short for Instrument. They usually use ¼” jacks and expect to see an unbalanced signal which most guitars provide.
Many consumer grade electronic products like CD players, DVD players, and Home Stereo components have output strength of -10dB. These are sometimes mistakenly called Instrument level. On things like mixers they are usually called AUX, CD, or STEREO INPUT and are frequently in the form of RCA plugs. Some pro audio gear has inputs that can accommodate -10dB. On our standard cheapo computer soundcards, this input would be labeled, “Line” and is usually 1/8” stereo.
Most Pro Audio and studio gear have average outputs of +4dB. Additionally some instruments such as synthesizers and drum boxes output at +4dB. Most all studio gear expects to see input signals which are this strong. This is called “Line Level.” (Not to be confused with “Line” on computer soundcards.) Most line level jacks are ¼” balanced or unbalanced.
Because so many jacks are similar, it is easy to incorrectly mix and match some types of equipment. While this probably won’t cause fatal damage to your gear, it can however cause serious noise or volume level problems. If you are serious about your recordings, then you should pay attention to Nominal Input Level Ratings listed in the specs of your gear. Correctly matching up output levels with input levels and matching up balanced signals when possible can make a world of difference.
Hope this helps.
These refer to the relative strength of an incoming signal in terms of dB level (volume). Average levels from different devices, (guitars, mics, CD players, etc.) can vary from -60dB to +20dB. This might not look like much in numerical values but it sure is a great deal in volume level. The ideal level of all incoming audio signals for recording would be at or about +4dB. Since so many different devices vary so widely this is an unrealistic expectation. We need a few different input types to accommodate those different levels. Common names are used on input jack labels but these can still be confusing or misleading if you don’t understand the whole “Big Picture”.
Why not just use one type?
It would seem at first glance that the industry lacks standardization for input levels. The pro audio industry does indeed have input standards. Consumer grade electronics have their standards too. We just tend to mix the standards from those different industries together. Most consumer grade audio products use -10dB and most pro audio gear uses +4dB. We audio engineers, D.J.s, soundmen, and hobbyist are the ones who mix and match different types of gear for different reasons. When you start mixing apples and oranges together, you just need to learn what works well and what does not.
If you plug a low level item into a device that expects a higher level, a lot of gain boost must be used to make up for the missing volume. In effect you end up boosting lots of noise along with the signal. This is called raising the noise floor. In a recording situation, this boosted noise may not be tolerable. Having inputs properly matched will work much better. The receiving input would be much more sensitive to the dynamics of the incoming signal and background noise could be left at a minimum.
To make matters even worse, most dynamic microphones fall very short for signal strength. They only average around -50dB. They almost always require some sort of boost in signal such as using a pre-amp. Dedicated preamps are better at boosting signal volume without boosting noise. Some equipment (like mixers) have preamps built in and are prepared to accommodate weak signals. These include some sort of input level control labeled as GAIN, TRIM, PRE, LEVEL or BOOST. These types of input jacks are usually XLR and are labeled “Mic”. These expect to see a balanced signal which most all modern mics do provide.
Guitars and basses tend to have a nominal level of -30dB but can vary greatly due to different pickup types. Some equipment has input jacks for this level. They would be called “Inst” short for Instrument. They usually use ¼” jacks and expect to see an unbalanced signal which most guitars provide.
Many consumer grade electronic products like CD players, DVD players, and Home Stereo components have output strength of -10dB. These are sometimes mistakenly called Instrument level. On things like mixers they are usually called AUX, CD, or STEREO INPUT and are frequently in the form of RCA plugs. Some pro audio gear has inputs that can accommodate -10dB. On our standard cheapo computer soundcards, this input would be labeled, “Line” and is usually 1/8” stereo.
Most Pro Audio and studio gear have average outputs of +4dB. Additionally some instruments such as synthesizers and drum boxes output at +4dB. Most all studio gear expects to see input signals which are this strong. This is called “Line Level.” (Not to be confused with “Line” on computer soundcards.) Most line level jacks are ¼” balanced or unbalanced.
Because so many jacks are similar, it is easy to incorrectly mix and match some types of equipment. While this probably won’t cause fatal damage to your gear, it can however cause serious noise or volume level problems. If you are serious about your recordings, then you should pay attention to Nominal Input Level Ratings listed in the specs of your gear. Correctly matching up output levels with input levels and matching up balanced signals when possible can make a world of difference.
Hope this helps.