Why Is My Mic Level So Low?

[beefeater267]

Hey,

I'm trying some recording of my amplifier and i find that my mic audio is so low. my gear is:

Fender Blues Jr
Shure SM57
ART MPA Gold Mic Preamp

Basically, i have the mic about 2 inches dead center in front of the amp and with i have to crank all the knobs on the preamp.

the preamp has an input gain and i need to put that around +40dB
the preamp has an audio output knob and i need to put that around +10dB
Those are maxed out for the values.
In addition, I have to toggle the +20dB switch as well

Is this normal? I heard that Shure SM57 are low sensitivity mics... but, i didn't think that low.

Any opinions?

[rgraves]

Originally Posted by beefeater267

Hey,

I'm trying some recording of my amplifier and i find that my mic audio is so low. my gear is:

Fender Blues Jr
Shure SM57
ART MPA Gold Mic Preamp

Basically, i have the mic about 2 inches dead center in front of the amp and with i have to crank all the knobs on the preamp.

the preamp has an input gain and i need to put that around +40dB
the preamp has an audio output knob and i need to put that around +10dB
Those are maxed out for the values.
In addition, I have to toggle the +20dB switch as well

Is this normal? I heard that Shure SM57 are low sensitivity mics... but, i didn't think that low.

Any opinions?

I always have to pump up the gain quite considerably on my preamp when using sm57 to record my marshall cab. And that's with the cab playing fricken loud. I think it's just normal.

Make sure you're only aiming to get around -18 dBFS anyways.

[MadAudio]

Well, we know the front end, but what are you using to record that signal with (soundcard, software)? Some audio hardware can be switched between -10 and +4.

[beefeater267]

I'm using a M-Audio Audiophile 192 PCI card..... I have 1/4in balanced cables from the preamp to the soundcard.

But, i'm not even introducing the soundcard as a variable yet. i'm determining low levels from the visual meters on the preamp. my amp is not too loud. it's bedroom level. maybe that's the problem. does it have to be 'wake up your neighbor' loud to get good input into the mic?

could it be a faulty preamp?

[rgraves]

Originally Posted by beefeater267

I'm using a M-Audio Audiophile 192 PCI card..... I have 1/4in balanced cables from the preamp to the soundcard.

But, i'm not even introducing the soundcard as a variable yet. i'm determining low levels from the visual meters on the preamp. my amp is not too loud. it's bedroom level. maybe that's the problem. does it have to be 'wake up your neighbor' loud to get good input into the mic?

could it be a faulty preamp?

Well, maybe MadAudio has some insight that I don't, but even cranking my marshall to 7 or 8, call the cops levels (which i usually do, in my basement of course ) it usually comes in 3 or 4 times quieter than a condensor, or even quieter than my sm58. Most peeps I've worked with say the same. I don't think you have a problem there.

[AGCurry]

+40 db is okay for input sensitivity (trim). The SM57 is kind of a medium-output dynamic mic, not too low, not too high. Does the preamp perhaps have a mic/line switch which you've overlooked?

I'd second MadAudio's question/comment, wondering what the input setting on your sound card is set at. What really matters is how well the preamp "feeds" the sound card, not what your VU meters say.

The VU meter on the preamp (I don't know this preamp) will tell you either what's happening on the front end or what's happening on the back end, but not both at once. IOW, if you're monitoring your input with the VU meter, adjusting the output level won't affect it...

[jonnyc]

Originally Posted by rgraves

Well, maybe MadAudio has some insight that I don't, but even cranking my marshall to 7 or 8, call the cops levels (which i usually do, in my basement of course ) it usually comes in 3 or 4 times quieter than a condensor, or even quieter than my sm58. Most peeps I've worked with say the same. I don't think you have a problem there.

That's pretty weird that it's more quiet than your 58 considering they're the same mic minus the housing around the capsule/diaphram. Fact is, it just takes more gain to push a dynamic mic, and yes you need to crank the volume, but not to get acceptable levels rather acceptable tones. That's a whole other topic all together.

[MadAudio]

Originally Posted by jonnyc

That's pretty weird that it's more quiet than your 58 considering they're the same mic minus the housing around the capsule/diaphram. Fact is, it just takes more gain to push a dynamic mic, and yes you need to crank the volume, but not to get acceptable levels rather acceptable tones. That's a whole other topic all together.

There's some kind of gain structure problem happening here IMO.

[SouthSIDE Glen]

Originally Posted by beefeater267

Basically, i have the mic about 2 inches dead center in front of the amp and with i have to crank all the knobs on the preamp.

I think your mic technique is a real part of it.

First of all, I'd try taking the mic off of dead center. There you're micing the dustcap, not the speaker driver. Most of the sound - not to mention most of the good sound - is blowing right past the sides of the mic. Try moving your mic over the speaker cone instead of the dustcap so you're actually grabbing some of the energy coming off the driver. Exact position depends upon the sound you desire, but for the sake of testing levels, you might want to start just inside the cone so that the side of the mic closest to the dustcap is just about where the voice coil surrounding the cap is located. Use that, along with the next paragraph, to see if that improves your levels. Then you can adjust exact position and angle for sound from there.

Second, 2" off the grille is quite a distance for a 57, especially at lower amp volumes. Not that it can't be miked that way, but it's sometimes amazing how much of a difference an inch or two in distance can make in volume when miking a git cab with a 57. One of my live bands has a guitarist that uses a Fender DeVille (4x10) that - for reasons too long and tangential to the thread to go into here - we also mic with a 57 and send through the PA just for a little reenforcement. The 1" difference between having the mic only 1" off the grille and putting it practically right on the grille makes all the difference in the world. And that's a live club volumes too, not bedroom-keep-the-cops-away volumes. Move that mic in; don't be afraid to get it up almost on the grille if you have to. But at least try moving it in somewhat; 2" can be a mile with that setup.

G.

[rgraves]

Originally Posted by jonnyc

That's pretty weird that it's more quiet than your 58 considering they're the same mic minus the housing around the capsule/diaphram.

yeah, I had thought it was weird at first, but I just figured that the response curve of the two mics had something to do with it. Heck, who knows, maybe my 57 is faulty or somethin. But even when I throw both mics on my PA and have a singer try both, the 57 is always noticably quieter. It's not huge or anything, but you can tell without even thinking about it.

[beefeater267]

Someone told me it may be an impedance mismatch. The shure is rated 310 ohms and my preamp can vary from 150 - 3K ohms. i find that i get better results when i set the preamp to 3K ohms. originally i was matching the levels. could this be part of the problem?

[tarnationsauce2]

Yeah, "matching" inpedance doesn't always mean a 1:1 ratio (actually almost never in the case of mics).

The higher impedance input on your pre will give less of a load on the microphone. More load means less output. And the frequency response will be narrowed.

Generally speaking, I would keep it over 1k on your pre. Default to 3k when zeroing your pre.