SPL stands for? Impedence Means?

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Massimo

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Hi, what does SPL stand for? And what's impedence mean?

Massi
 
Sound pressure level (think of it as loudness) of an acoustic wave in a medium.

Impedance is resistance to an alternating waveform - could be electric, acoustic, or others forms of energy.

Both of these terms have many ramifications in acoustics and electronics. Do a google search - lots of info.
 
The higher SPL handling rating--the louder signal without distortions you get.
For maximum performance without frequency response and distortions compromises, all input and output impendances of the equipment should be carefully matched. Usually, input impedance should be at least 5 times higher than source impedance (the output impedance of the previous stage). Here there may be some confusions, as some manufacturers specify actual input impedance, and some--matching impedance (i.e. what impedance it works with).
 
Think of impedance matching like a baseball player swinging at a ball. If he misses, there's no transfer of energy from the player through the bat to the ball. If he were to hit a steel pipe standing in the ground in front of him, all the energy would be transferred but no work would be done. If he hits the ball squarely, he transfers the maximal energy to the ball and it goes out of the park. This is an impedance match.

This is how you want electrical devices to connect to each other, so the maximum useful work is transferred from one to the next.

Read a little more here.
http://www.homerecording.com/bbs/showthread.php?s=&threadid=103003
 
Massimo said:
I lost you after the first sentence.

Thanks anyway.

Massi
Click to expand...
Well, to clarify the SPL. It is the loudest sound that the microphone can accurately and safely turn into a singal. If you try to record a sound that is louder than that you are not going to get a good singal and you may also actually damage the microphone.
 
SPL means Sound Pressure Level. It is a measure of loudness of sound that is defined relative to the units of air pressure, the Pascal, which is one newton (force) per square meter (area).

Specifically:

SPL = 20*log10(P/2E-5 Pa)

where P is the measured AC sound pressure in Pascals and 2E-5 is shorthand for .00002

log10() means logarithm base 10. That means that 0 dB SPL will be 2E-5 Pa and that 1 Pa, the usual reference for mic sensitivity, is 94 dB SPL.

Confused yet? :-)


Bob
 
arcanemethods said:
SPL means Sound Pressure Level. It is a measure of loudness of sound that is defined relative to the units of air pressure, the Pascal, which is one newton (force) per square meter (area).

Specifically:

SPL = 20*log10(P/2E-5 Pa)

where P is the measured AC sound pressure in Pascals and 2E-5 is shorthand for .00002

log10() means logarithm base 10. That means that 0 dB SPL will be 2E-5 Pa and that 1 Pa, the usual reference for mic sensitivity, is 94 dB SPL.

Confused yet? :-)


Bob
Click to expand...


Ah very well Bob. Yes your explanation is very confusing , thank you. You say the usual reference for mic sensitivity is 94 db SPL, interesting. I'll have to check my SM57's SPL, just out of curiousity.
 
crazydoc said:
Think of impedance matching like a baseball player swinging at a ball. If he misses, there's no transfer of energy from the player through the bat to the ball. If he were to hit a steel pipe standing in the ground in front of him, all the energy would be transferred but no work would be done. If he hits the ball squarely, he transfers the maximal energy to the ball and it goes out of the park. This is an impedance match.

This is how you want electrical devices to connect to each other, so the maximum useful work is transferred from one to the next.

Read a little more here.
http://www.homerecording.com/bbs/showthread.php?s=&threadid=103003
Click to expand...

Intersesting analogy, so the mic is the bat and what would the ball be?

Changing the subject--I've been hearing alot about pre amps. A pre amp is a box that gives power to a mic? When do you use a pre amp?
 
Massimo said:
Intersesting analogy, so the mic is the bat and what would the ball be?

Changing the subject--I've been hearing alot about pre amps. A pre amp is a box that gives power to a mic? When do you use a pre amp?
Click to expand...
Well, in this case I guess you could call the ball the preamp, or the next device in the signal chain.
The preamp is an amplifier that increases the level of the audio signal from mic level (very low) to line level (higher) to be used by other devices (effects, console, or amplifier, etc.) Some preamps have a power supply that sends power to microphones that need it to run the mic's interneal amplifier (condenser mics.) This is called phantom power. Mics like the Shure SM57 are dynamic type mics, and don't need phantom power, though it won't hurt them.
All mics need preamps. Many consoles and other recording devices have preamps built into them, so you don't need a separate preamp, though you can use one if you desire.
 
crazydoc said:
Well, in this case I guess you could call the ball the preamp, or the next device in the signal chain.
The preamp is an amplifier that increases the level of the audio signal from mic level (very low) to line level (higher) to be used by other devices (effects, console, or amplifier, etc.) Some preamps have a power supply that sends power to microphones that need it to run the mic's interneal amplifier (condenser mics.) This is called phantom power. Mics like the Shure SM57 are dynamic type mics, and don't need phantom power, though it won't hurt them.
All mics need preamps. Many consoles and other recording devices have preamps built into them, so you don't need a separate preamp, though you can use one if you desire.
Click to expand...

Oh I see, that's probably why when I record my guitar amp using my mic I have to turn the trim very high just to get a good signal. So if I bought a pre amp this would boost up the mic and improve it's picking up. What are some good common pre amps?

Thanks
 
Thanks Crazy, I noticed these ads mention the pre amps function for PC based recordings. Are pre amps usually used for general purpose recordings also, like let's say with the Korg D1200? I mean I know I can record and get a good signal without one now, but will having one improve things or just make it easier to get a proper signal?
 
I don't have any experience with the Korg, but in general outboard preamps will at least give you more choices in sound quality, if not better quality also.
 
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