Steenamaroo
...
Kip, I'm Paul!
kip4
Well-known member
Paul I know your Paul.
Sssh don't tell the others then I look like i know what i'm talking about for once.
Sssh don't tell the others then I look like i know what i'm talking about for once.
M
moresound
Loud Sun Studios
Blessed are the cheese makers
Steenamaroo
...
Sorry, are you talking to me?
Steenamaroo
...
M
moresound
Loud Sun Studios
kip4
Well-known member
My all time favorite film. I had to stop watching it because mrs Kip got pissed at me for reciteing the lines before the actors did.
kip4
Well-known member
And I used to teach my guitar students this song too.
kip4
Well-known member
On a differant matter Thank Brian this was before the loudness wars. It would have absolutely killed it.
"Worse things happen at sea you know"
"Worse things happen at sea you know"
Steenamaroo
...
Dude, I recently took a flight with my pal, (Pete, just to confuse matters).
He had this idea just before boarding and actually sat in silence waiting for the right moment.
He waited until we were at cruising altitude then turned to me and said "Not so bad once you're up"
That's commitment right there.
He had this idea just before boarding and actually sat in silence waiting for the right moment.
He waited until we were at cruising altitude then turned to me and said "Not so bad once you're up"
That's commitment right there.
ollie99
New member
congratulations to bobbsy for writing the best explaination to my question 
thanks I understand now
thanks I understand now
M
moresound
Loud Sun Studios
S
soundobsessed
New member
...to complete the picture...
Although all basically correct, I think Bobbsy's explanation is the most technically clear and accurate. However, even though a preamp can be understood in simple terms of voltage alone - what's commonly called "signal level" - that's only part of the story.
OK, now if you're in a hurry it's OK to jump to “Here's all you need to know” below.
For just the brave souls...
Besides voltage, any analog audio circuit (or any electric circuit at all, for that matter) also has three other important aspects:
Power, expressed in Watts and designated with the letter P or W.
Current, expressed in Amperes or Amps and designated with the letter A.
and Impedance - or "AC Resistance" - expressed in Ohms (sometimes symbolized by the Greek letter "Omega" which looks like a horseshoe open on the bottom), it is also sometimes designated with the letter Z.
To complicate matters further, Impedance is often confused with a fifth aspect: DC Resistance. Although expressed in Ohms like Impedance, DC Resistance is only used for describing pure DC circuits.
So, how can any sense be made of all this? I've personally had good luck with simplifying it to just two of the five parameters - Voltage and Impedance. You can usually ignore the other three (Power, Current, and DC Resistance) without suffering too many problems in selecting gear. Power was critical in the old days because of primitive circuit techniques, but it's usually important now only when dealing with power amps and speakers. As for DC Resistance, that can be ignored because all audio is by nature AC (Alternating Current; Note: don't let the word "Current" throw you. Here Current implies the four other terms; except (as noted above) sometimes for pure DC circuits, none of them can exist without all the others).
So how does this help us understand mics and preamps?
Here's all you need to know:
About the mic you want to use:
1. The sensitivity spec given for the mic in decibels (-dB). Keep in mind that the bigger the sensitivity number the quieter the sound you can pick up with that mic.
2. The mic's Output Impedance in Ohms.
About the preamp that will work for that mic:
1. Check that it has a maximum Voltage Gain in the ballpark of the mic's sensitivity, say, plus or minus 10dB. Taking for example a mic sensitivity of -60dB, you'd want preamp max gain in the range of 50 to 70dB.
2. Check that its Input Impedance is in the range of the mic's Output Impedance AT THE VERY LEAST, to up to five or six times the mic's Output Impedance. So, for a mic Output Impedance of 300 Ohms, you'd want the preamp's Input Impedance to be in the range of 300 to 1,000 or even 2,000 Ohms. Note that some of the more sophisticated preamps actually have a variable Input Impedance or “loading” control that can be used to “tune in” a certain coloration of sound.
See – nothing to it!
Although all basically correct, I think Bobbsy's explanation is the most technically clear and accurate. However, even though a preamp can be understood in simple terms of voltage alone - what's commonly called "signal level" - that's only part of the story.
OK, now if you're in a hurry it's OK to jump to “Here's all you need to know” below.
For just the brave souls...
Besides voltage, any analog audio circuit (or any electric circuit at all, for that matter) also has three other important aspects:
Power, expressed in Watts and designated with the letter P or W.
Current, expressed in Amperes or Amps and designated with the letter A.
and Impedance - or "AC Resistance" - expressed in Ohms (sometimes symbolized by the Greek letter "Omega" which looks like a horseshoe open on the bottom), it is also sometimes designated with the letter Z.
To complicate matters further, Impedance is often confused with a fifth aspect: DC Resistance. Although expressed in Ohms like Impedance, DC Resistance is only used for describing pure DC circuits.
So, how can any sense be made of all this? I've personally had good luck with simplifying it to just two of the five parameters - Voltage and Impedance. You can usually ignore the other three (Power, Current, and DC Resistance) without suffering too many problems in selecting gear. Power was critical in the old days because of primitive circuit techniques, but it's usually important now only when dealing with power amps and speakers. As for DC Resistance, that can be ignored because all audio is by nature AC (Alternating Current; Note: don't let the word "Current" throw you. Here Current implies the four other terms; except (as noted above) sometimes for pure DC circuits, none of them can exist without all the others).
So how does this help us understand mics and preamps?
Here's all you need to know:
About the mic you want to use:
1. The sensitivity spec given for the mic in decibels (-dB). Keep in mind that the bigger the sensitivity number the quieter the sound you can pick up with that mic.
2. The mic's Output Impedance in Ohms.
About the preamp that will work for that mic:
1. Check that it has a maximum Voltage Gain in the ballpark of the mic's sensitivity, say, plus or minus 10dB. Taking for example a mic sensitivity of -60dB, you'd want preamp max gain in the range of 50 to 70dB.
2. Check that its Input Impedance is in the range of the mic's Output Impedance AT THE VERY LEAST, to up to five or six times the mic's Output Impedance. So, for a mic Output Impedance of 300 Ohms, you'd want the preamp's Input Impedance to be in the range of 300 to 1,000 or even 2,000 Ohms. Note that some of the more sophisticated preamps actually have a variable Input Impedance or “loading” control that can be used to “tune in” a certain coloration of sound.
See – nothing to it!
Bobbsy
Boring Old Git
Hmmm...well, if we're going to get into the details, I'd say you've forgotten a crucial number in your evaluation. It's not just the gain figure for a particular pre amp--you also need to know about the noise being added by the pre amp for a specific amount of gain. This is where most budget pre amps fall down (and even some expensive ones). Once you turn up the gain beyond about 3/4 level, they often add objectionable noise.
Of course the trouble with this is that, where numbers aren't favourable, manufacturers specs can be "economical with the truth". They're either left out entirely or contain weasel words that hide the whole story (i.e. specifying noise for the lowest gain setting or talking about narrow band noise at a "good" frequency). At the risk of sounding a bit condescending, unless you have an electronics background, trying to use manufacturers spec sheets to choose gear (including pre amps) is probably doomed to frustration and failure.
The good news is that, unless you venture into specialist "boutique" mics and pre amps, most mics will work fine with most pre amps. The main place to exercise caution would be pairing certain dynamic mics with certain pre amps (including pre amps built into interfaces). Some favourite dynamics have very low outputs and, unless you have oodles of clean gain, you can get unpleasant noise. Luckily, this doesn't apply to the vast majority of mics that tend to be discussed and recommended on the HR!
(Edited to add: I'll leave it to you to get into the significance of voltage vs. current vs. power vs. impedance and things like dBu vs dBV if you want to! That's a can of worms best left to a technical forum, not one populated mainly by musicians!)
Of course the trouble with this is that, where numbers aren't favourable, manufacturers specs can be "economical with the truth". They're either left out entirely or contain weasel words that hide the whole story (i.e. specifying noise for the lowest gain setting or talking about narrow band noise at a "good" frequency). At the risk of sounding a bit condescending, unless you have an electronics background, trying to use manufacturers spec sheets to choose gear (including pre amps) is probably doomed to frustration and failure.
The good news is that, unless you venture into specialist "boutique" mics and pre amps, most mics will work fine with most pre amps. The main place to exercise caution would be pairing certain dynamic mics with certain pre amps (including pre amps built into interfaces). Some favourite dynamics have very low outputs and, unless you have oodles of clean gain, you can get unpleasant noise. Luckily, this doesn't apply to the vast majority of mics that tend to be discussed and recommended on the HR!
(Edited to add: I'll leave it to you to get into the significance of voltage vs. current vs. power vs. impedance and things like dBu vs dBV if you want to! That's a can of worms best left to a technical forum, not one populated mainly by musicians!)