Instructables

What is line level output?

I saw it in Kaustic Machine's schematic for the Atari Punk Console. Does anybody know what it is?

framistan2 years ago
Microphones only put out millivolts of audio even if you scream into the mic. This isn't enough voltage to drive a power-amp that connects to speakers. So, a PRE-amp is connected to the microphone to bring up those millivolt voltages to LINE LEVEL. For the consumer electronics industry, that is 0.316Volts (-10dBv) In the professional audio world that would be 1.23Volts or +4dbu.

This question can be further complicated due to other countries have varying standards. Of course, i assume you are asking from the USA.... but maybe you are from another country that has some other standard?

The important thing to do.... is to have audio levels HIGH enough to be well-above the "noise-floor" and also LOW enough to be below "clipping" levels. For example, lets say you have a microphone that has its own volume control, which feeds an equalizer with its own volume control... feeding a PRE amp with another volume control. If you turn the volume down TOO LOW on the microphone, then try to compensate for that by turning the OTHER items up, you will be amplifying the NOISE FLOOR and it will not sound good. If however, you turn the mic too HIGH and this overdrives the mixer into distortion (clipping) you will try to turn down the pre-amp to compensate for the "too loud" signal. However this will fix the LOUDNESS problem, but the distortion will still be there!

The answer is to start at the microphone and have reasonable levels coming out to feed the equalizer. Then the mixer output must be adjusted for reasonable levels to feed the PRE-amp. If levels are kept ABOVE the noise floor, and BELOW clipping then the final volume control can pass GOOD levels to the power amp without noise or clipping.

blinkyblinky (author)  framistan2 years ago
Beautiful...

>insert dreamy look on face here<

This is what I am looking for.

Yahoo! Search found this info. Google would have found the same (after the sponsored results).  Take from it whichever specification is easiest for you to use.

Qa

blinkyblinky (author)  Quercus austrina2 years ago
It doesn't explain what -4db output is.
How about this search for calculators?

Qa
blinkyblinky (author)  Quercus austrina2 years ago
What is it though???
Line level is the amount of gain normally used for a line input as opposed to mic level. This is an audio basic... as suggested before... GOOGLE IT ALREADY!!! There should be plenty of info about it out there. If you have already googled what is line level? and you don't understand it, try "what is the difference between mic and line level?".
blinkyblinky (author)  thegeeke2 years ago
Yes. In fact I have googled it multiple times...I guess I'm not googling it right. Either way, thank you. I am only starting out in electronics so give me a break.
Check out this link... 4th comment down. Explains it pretty well.

First read the Wiki I linked to in my first post. Digest it for a few minutes.

Now, using this calculator and putting 0.63 in the far right box (marked V [_____] volts (RMS)) will give you a close answer to -4 dBV. If your meter can read RMS values, set the output of the APC to read 0.63 and leave it set there. Good to go.

The reason I led you this way is to let you discover just what the Bel unit is and to realize that unless you can set up the necessary situation required to take the readings (note the "s" as you will need to make at least 2 readings) and do the math. It is easier to find out the equivalent (relatively speaking) voltage to measure to make sure you are "close enough".

Qa

gmoon2 years ago
"Line level output" is a standard for consumer audio electronics. It's the most common signal level for preamps, CD players, MP3 players, computer audio, etc.

Any audio equipment that is "line level" will work well together.

What is it technically? It's an output level with just enough "oomph" to drive other preamp-level devices. The voltage level is limited to less than +-2 volts peak-to-peak. And it has relatively low output impedance, so it has just enough power to drive something else.

What does that mean? Output and input impedance are pretty slippery concepts. The lower the output impedance, the easier it is to drive the next stage (preamp, power amp) without any signal losses.

(Input impedance is completely opposite--a low input impedance is usually not a good thing. But it all depends on the context.)

Line inputs still have very low power output--they cannot drive a speaker, for instance. But that's not the point--they are preamp level, and that's why they can be safely plugged into other "line level" equipment...
lemonie2 years ago

It's essentially a powered-output, as opposed to a weak signal such as you get from a microphone or an unamplified radio-receiver.

L
Vyger2 years ago
I have a line level. It snaps onto a string and tells you which end of the string is higher or if its level with the ground. In this case the output would be when you read the bubble and determine how level something is.