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Muddy live sound with my mic turned on!??!

Oh! Henry

Oh! Henry

Dec 7, 2006
422
26
Montreal, Quebec
#1
I noticed the other day at rehearsal that my bass amp was sounding very muddy and undefined. I've had this problem at gigs and never knew what caused it. However when I turned off my SM58 vocal mic (which is about 5-6 feet in front of my cab) the muddiness went away. Anybody know why this happens and how to fix the problem without having to turn off my mic?

Thanks
Henry
 
#2
Position the mic so it's off-axis to the cab and throw a hi-pass filter on the mic's channel in the PA. Unless you're singing basso profundo, an 80Hz HPF will be plenty low enough to leave your vox unaffected. Tenors might benefit from a slightly higher cut-off, if you have the capabilities for it.

Also, for the record, ALL of the mics should be hi-passed except for the bass drum, a mic on your cab, and possibly the floor tom. It keeps the mud out of the mix.
 
#3
The mic is picking up the bass, but there's a time delay between when the sound hits the mic and when it hits your ears. Also, it's picking up a lot of other stuff going on in the room too. When I run sound, I kill every mic that's not being used right now to prevent this.

The low frequency roll of is another great idea. There's just about NOTHING useful in the real world below 40 Hz, and nothing in anything except kick, bass, and maybe keys that's going on below 80 Hz.

John
 
#4
Nick Kay said:
Also, for the record, ALL of the mics should be hi-passed except for the bass drum, a mic on your cab, and possibly the floor tom. It keeps the mud out of the mix.
Click to expand...

I would even high-pass the floor tom(@around 40Hz) and the cab mic (depending on the speaker size, 10" hardly produces anything under 80Hz, the rest of it is the port...). Kick drum, maybe...
 
#5
kalle74 said:
I would even high-pass the floor tom(@around 40Hz) and the cab mic (depending on the speaker size, 10" hardly produces anything under 80Hz, the rest of it is the port...). Kick drum, maybe...
Click to expand...

Oh, of course, given the opportunity, hi-pass everything. Unfortunately, most consoles only have the per-channel hi-pass filter set at or around 80Hz. If you can dedicate a parametric EQ with variable hi-pass to each channel, it's a good call, but most acts don't have the means to do that. Best compromise is to use the 80Hz filter where you can, and hope that the subsonic filters on your amps or the EQs on the mains and monitors take care of the muck below 40Hz on everything else.
 
#6
Nick Kay said:
Oh, of course, given the opportunity, hi-pass everything. Unfortunately, most consoles only have the per-channel hi-pass filter set at or around 80Hz. If you can dedicate a parametric EQ with variable hi-pass to each channel, it's a good call, but most acts don't have the means to do that. Best compromise is to use the 80Hz filter where you can, and hope that the subsonic filters on your amps or the EQs on the mains and monitors take care of the muck below 40Hz on everything else.
Click to expand...

An fMod before the poweramp could clear everything below whatever frequency you want
 
#7
totallybacan said:
An fMod before the poweramp could clear everything below whatever frequency you want
Click to expand...

Eh, usually not any more or less effective than the filters on the poweramps. Those dirty subsonics have already had their chance to wreak havoc in the effects busses and summing amp. A reverb or delay that gets high-passed on the output will sound significantly murkier than one that gets high-passed on the input. The best call really is to take care of the problem as early in the signal chain as possible - like right after it hits the mixing desk.
 
#8
Thanks guys,

I'm a total noob when it comes to live sound settings. I'm not even sure if our mixer has a hi-pass filter but I'll be checking this out at our next rehearsal. I'll also check the placement of my cab.

Is there anything I can do to my signal or EQ differently to help fix this, or is this really just a PA issue?

thanks
 
#9
You need a mic that pics up less of the stuff you don't want it to pick up. The Audix OM7 is the best in this regard. Avaiable as B-stock/used for $150 or less. It's what I use for any rock band (or most any band with a drummer, unless he's a player instead of a pounder). The $60-used EV 767a might be good - I've not tested it enough to say for sure.
 
#10
TimmyP said:
You need a mic that pics up less of the stuff you don't want it to pick up. The Audix OM7 is the best in this regard. Avaiable as B-stock/used for $150 or less. It's what I use for any rock band (or most any band with a drummer, unless he's a player instead of a pounder). The $60-used EV 767a might be good - I've not tested it enough to say for sure.
Click to expand...

Yeah, a super- or hyper-cardiod mic will have better off-axis rejection than a cardioid like the SM-58. A Beta 87A might do the trick.
 
#12
TimmyP said:
The 87A is not one I read good comments about in this regard. It is a decent sounding mic, though.

All Hypers and Supers are not created equal. Just like with cardioids, some are tight, and some not so much.
Click to expand...

In all actuality, my brother and I use Beta 87Cs, which sound great. We got the C model because we had our monitors right in front of the mic stands, and cardioids have better rejection directly to the rear.
 
#16
JustDavid said:
58's are directional. The Beta more so than the SM.
Click to expand...


58's are Omni directional I thought??? Which means it picks up sound from the entire surface of the mic even the sides. Uni directional mics like 57's, only picks up sound if you sing into it right into the top or directly into it. That's why the 57's are usded to mic cabs and for back up singers not to get all that stage noise into the mix.
 
#17
Nope,. SM58's and SM57's are both cardio unidirectional. You wouldn't see an SM58 as the ubiquitous FOH vocal mic if they were omni. An omni picks up more or less evenly from all angles, and that's fatal with high volume and fold-back monitors.

The DEGREE of directionality can vary a LOT between different mics, but the SM58 is very much a directional mic.

John
 
#18
Try a limiter on your mic. If the overall sound is fine when you are on the mic, but is muddy when you step away from the mic, there is your problem. There was a mic muting system a few years ago that was mounted at the base of the mic. It had a proximity switch on it that would mute the mic when you moved away from it. Just another angle to look at the problem, in my humble opinion.
 
#19
JTE said:
Nope,. SM58's and SM57's are both cardio unidirectional. You wouldn't see an SM58 as the ubiquitous FOH vocal mic if they were omni. An omni picks up more or less evenly from all angles, and that's fatal with high volume and fold-back monitors.

The DEGREE of directionality can vary a LOT between different mics, but the SM58 is very much a directional mic.

John
Click to expand...

Hmm I see, thanks for the explanation John


So that degree of directionality is why 57's are used for micing cabs and backups and the 58's are used more for vocals I would assume. I have noticed 58's allow one to sing into the mic from the side versus the 57 you have to sing directly into it more.
 
#20
If I am not mistaken (which I may be...) the mic element in the 57 and 58 are the same. The mics vary in the housing, the 58 having a ball, the 57 without.
<edit> I checked to be "shure" and here is what shure says:
The SM58 and SM57 do use the same cartridge. The grill, though, does effect the frequency response to some extent. At a distance, the difference is probably not noticable. But at extremely close distances, the difference is noticeable. Due to the grill, a person's mouth can get closer to the diaphragm of an SM57, thus causing more proximity effect and increased bass when compared to the SM58.

Note that the cartridges are not interchangable because the mounting scheme is different for the two microphones.
 

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