sm57 hiss

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steveyab

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i have an old m audio mobile pre interface and to boost the microphone to any reasonable levels creates a horrible hiss. i can't record with such a noticable hiss it's driving me nuts. what's the best (and/or cheapest) way to fix my problem? should i buy a preamp? a new interface? how much would i have to spend for one good enough that doesn't hiss with my sm57
 
Have you plugged it into a mic input or have you tried plugging it into a line input? I use SM57's all the time and they are not noisy unless the gain is cranked right up.

What model M-Audio is it?

Cheers
Alan.
 
it's in the xlr input. the model is "m-audio mobile pre" as stated in the original post. phantom power is not on, it's a dynamic. i HAVE to crank the gain to get a decent signal from the sm57 , and the mobile pre preamps are so noisy they introduce a ton of hiss if i raise the gain to a decent level.

once again, what is the cheapest/best solution to this? an external preamp? or a better interface?
 
Ok I have downloaded the manual and had a look. The mic pres on the M-Audio should work better then you are experiencing.

To get the level up I guess that you are turning up the volume knob on the front of the unit. Have you checked the settings on the internal digital mixer to see what the volume setting are there? If they are turned down that would explain why you have to turn up the knob so much.

If the volume is turned up on the digital mixer, check that it is not turned down somewhere within the recording software.

Let us know how you go.

Cheers
Alan.
 
i have my volume knob a little less than half (seems to be a good volume for most songs)

for the m-audio software mixer thing i have input , monitoring, and output all at 0 dbs.. input goes up to +12 but 0 is near the top and i was told by someone that all 0's is good.

i have to turn the pre amp to 3/4ths to get a decent signal, and i start to get noticable hiss after 1/2 .. if i turn my volume knob higher the hiss gets even louder.

also when i unplug the mic the hiss goes down a little bit, but is still there and quite loud

edit- it seems that whatever mic i connect to the cord, the hiss gets louder, even if the mic is off.. i connected a condenser microphone (with phantom OFF) to the xlr cable and the hiss got slightly louder and i picked up a radio station :S
 
On the mixer you can push the volume controls up past 0 as long as the vu meters don't show an overload when you are recording. If you push the volume controls up and turn the knob down does the noise reduce for the amount of volume the mic has, i.e less hiss for the same mic volume?

Is there a problem with the microphone lead as you should not pick up radio stations? Is there a problem with the SM57? How is the volume when using the condenser mic with phantom power?

Cheers
Alan.
 
Picking up the radio station is probably caused by using a cable that doesn't ground the metal barrels on the ends. Probably worth modifying it by adding a jumper wire on both ends if you're using the cable exclusively with microphones.

The noise level might be caused by that, but is probably just the typical noise level of the Mobile Pre. Its noise level is all over the map, with some people reporting noise floors as high as -40 dB instead of the -65 dB that the thing is supposed to do (or so I've read). Even at -65 dB, though, that's way, way too noisy to use with dynamic mics, and it is borderline even for condenser mics. The SM58's sensitivity is -54.5 dB, which essentially gives you only about 10 dB signal-to-noise ratio. Not good. (And for the ones with noise floors as high a -40 dB, it becomes a noise-to-signal ratio. :D )

Either get a better preamp or get an audio interface that has better built-in preamps. If you decide to go with a standalone preamp, I recommend the Peavey PV series of mixers. Noise floor is about -129 dB (A weighted). I use mine with ribbons periodically, and they have about the same sensitivity as an SM58.
 
dgatwood said:
Picking up the radio station is probably caused by using a cable that doesn't ground the metal barrels on the ends. Probably worth modifying it by adding a jumper wire on both ends if you're using the cable exclusively with microphones.
Click to expand...

The worry for me is that the condenser was connected (without phantom) and a radio station was picked up.

Cheers
Alan
 
i tried different cables and different mics, all leading to the exact same result of more hiss + faint radio signal once connected to a microphone, even if the microphone is turned off.

even without a cable plugged in though the hiss is too loud.. but if i could reduce this "Extra" hiss it would definitely help some.. anyone have any ideas ?


also, what is a good upgrade from the mobile pre interface wise with good enough preamps for the sm57? since i'm planning to jump to 24 bit anyways.. or will i need a external pre amp either way
 
Are you running on a laptop? You might try running on battery power and see if you still have the noise. I have a mobile pre and an Audix i5. It's not the quietest interface on the planet, but it's not as bad as you're describing.

What are you micing? How far is it from the mic? Dynamics need a lot of gain, and/or proximity. It doesn't seem like you're too off at about 1/2 around on the gain knob. You could try using a lower gain and adding gain in post. If the noise level is significantly lower that route, then there's an issue with the interface and/or it's preamps. Do both channels have the same high noise? Or is one noisier than the other? XLR input is about as good as it gets. TRS might have high-Z or other woes, although not on that interface iirc. You could try a new / different USB cable. I bought mine used the the cable that I got with it sucked. I actually had to pull it halfway out to get the interface to even work with that cable.

As far as the radio station thing. Not a good sign for your recording location. You might try wrapping the cable connectors in tin foil (shiny side out) and see if that helps. If it does, you might look at different cables / connectors. If not that probably doesn't mean anything. I've picked up a radio station before on condensers. Raising or lowering the mics seemed to help mitigate it. But I was on alumnimum bleachers and was able to tuck the field recording under for extra help. There are some mics designed around RF rejection, so it could be the mics as well. Or the interface.
 
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