SPL Levels vs SPL of Mic

[gcapel]

Lets say I were to take a spl meter and measure parallel with the mic. What is good percentage to be in relation to the microphones rated SPL level?

Will this vari on the type of mic?

Especially on guitars amps, I want to crank the tubes to get great tone. But I don't want to border line max out the microhpones spl level.

 

[mshilarious]

Especially on guitars amps, I want to crank the tubes to get great tone. But I don't want to border line max out the microhpones spl level.

Mics are usually rated at SPL that generates 1% total harmonic distortion (THD). Up until that point, distortion, at least compared with the distortion from a guitar amp, is negligible. So you don't need to worry about SPLs up to or at that level.

Sometimes there will be a rating for absolute maximum SPL, either because it could damage the mic, or because the signal would be clipped.

The usual suspects for micing a guitar cab can take much more punishment than a cab can dish out. Sometimes there aren't published specs, often that is because the mic can take higher SPLs than can be tested.

 

[Robert D]

I think most tube guitar amps, once driven into saturation like that, are acting almost like a compressor, and therefor aren't prone to a lot of peaks above "11". So, I don't think you need to have a lot of buffer in between the mic's rated SPL and the actual SPL it's seeing, assuming the mic's manufacturer was honest in their testing and literature........often a pretty big leap of faith. I'd think you're pretty safe at 90% of rated SPL.

 

[mshilarious]

Lets say I were to take a spl meter and measure parallel with the mic. What is good percentage to be in relation to the microphones rated SPL level?

Oh, one thing about that, my Rat Shack meter caps out at 126dBSPL. Cabs can get louder than that when you place the thing an inch from the cone. I will guarantee that your favorite dynamic mic can easily withstand that level, as I have tested a few of them (B52, e609, M201 . . .) all with THD well under 1%, often more like 0.2%.

Also, dBs aren't percentages, they are logarithmic, so 120dB is 50% of 126dB. Distortion does not follow that curve; a mic might be 0.2% at 94dBSPL and 0.4% at 116dBSPL, as an example.

 

[gcapel]

Thanks for the info. I was debating if i should buy a spl meter or not. I saw one in the marketek book that looked like a good quality meter.

I guess I;ll keep cranking the tube amp till it sounds good.

 

[SouthSIDE Glen]

Remember that what sounds best to your ear does not necessarily sound best to the microphone. Most of the recordings you've heard that sounds like the git amps are cranked are actually recorded at much lower volumes than you'd think.

This is a common problem in studios with musician clients that are rookies at the recording process. They keep insisting on cranking their knobs to twelve because they want "that sound", and they just don't trust or beleive the engineer when he/she says "that sound" is actually best reproduced by recording at more moderate levels.

G.

 

[gcapel]

Remember that what sounds best to your ear does not necessarily sound best to the microphone. Most of the recordings you've heard that sounds like the git amps are cranked are actually recorded at much lower volumes than you'd think.

This is a common problem in studios with musician clients that are rookies at the recording process. They keep insisting on cranking their knobs to twelve because they want "that sound", and they just don't trust or beleive the engineer when he/she says "that sound" is actually best reproduced by recording at more moderate levels.

G.

Good stuff here.

So glen, this being said. Is it better to drive the source more (mic) or drive your preamp more to maintain your -18db digital level?

 

[Robert D]

Good stuff here.

So glen, this being said. Is it better to drive the source more (mic) or drive your preamp more to maintain your -18db digital level?

Driving the mic more means making the source louder, which may or may not be best. IMNGO (In my not Glen opinion), the source should always get the highest priority, meaning it should be whatever makes it sound the best as an acoustical event, including it's interactions with the room. Then adjust the preamp gain accordingly.

 

[Farview]

Good stuff here.

So glen, this being said. Is it better to drive the source more (mic) or drive your preamp more to maintain your -18db digital level?

It doesn't matter. You get the amp to sound the way it needs to and then turn the knob on the preamp until you get the proper level.

 

[SouthSIDE Glen]

Good stuff here.

So glen, this being said. Is it better to drive the source more (mic) or drive your preamp more to maintain your -18db digital level?

IMAWBRDAFOWALETI*, get it right at the mic first and always. Whatever it takes (within some sembelance of reason ) to get the sound (quality, not volume) as perfect as possible at that boundary is the key to everything else.

By definition, a microphone's job is to capture the sound and convert it to an electrical signal. A preamp - by definition - has the job of bringing that mic signal up to a specified line level.

Neither you or the preamp should expect the microphone to shoulder the burden of the preamp.

G.

*In My Agreeing With RobertD's and Farview's Opinion With A Little Extra Thrown In