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Vocal Mic Feedback: Cardioid vs Super/hyper Cardioid


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My drummer son and I have just started a duet ala the Black Keys or White Stripes.

 

Our rehearsal setup for the moment is:

 

- Acoustic drums

- Guitar through my cranked 17 watt Goodsell

- Me on vocals into Allen & Heath MixWiz 12 and out to two QSC K12 floor

monitors.

 

I'm having trouble getting enough gain before feedback with my supercardioid AKG D870 dynamic mic. It's a great little mic for the money and has served well on acoustic gigs. But it doesn't seem to be cutting it here. In fact, I have to put my amp across the room facing us for practice or it really howls.

 

Wondered if a cardioid pattern would be better since it supposedly wouldn't pickup anything behind the mic (i.e., monitors). And I'd like to move the amp back over near me like it would be at a gig.

 

In particular, I'm interested in the Shure 55 SH mic which is cardioid.

 

http://www.shure.com/americas/products/microphones/classic/55SH-Series-II-iconic-unidyne-vocal-microphone

 

I'd appreciate experienced opinions and guidance.

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Have you EQ'd the room to cut the feedback out? Any acoustical treatment in the room?

 

Audix OM7 is one of the top choices to feedback problematic rooms.

 

It takes practice, proper gain structure and EQ'ing to perfect feedback control. I can have a singer with an SM58 crouch almost to the grill of a Microwedge before it

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I'm having trouble getting enough gain before feedback with my supercardioid AKG D870 dynamic mic. It's a great little mic for the money and has served well on acoustic gigs. But it doesn't seem to be cutting it here. In fact, I have to put my amp across the room facing us for practice or it really howls.


Wondered if a cardioid pattern would be better since it supposedly wouldn't pickup anything behind the mic (i.e., monitors). And I'd like to move the amp back over near me like it would be at a gig.


 

 

I'm not grasping this....

 

Is your vocal mic feeding back, or is your guitar amp mic feeding back or....

 

What do you mean by your amp howls? Do you mean your monitor speakers...?

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Hey Guys, I'm a nubile with sound equipment as I just started putting together my own system plus I've played mostly bluegrass for 20 yrs.

 

The room is about 300 square ft, carpeted, with no acoustic treatments. It's also my son's bedroom separated from the rest of the house by the carport. Ain't much but it's what we've got.

 

I know I should get a 32-band eq but just haven't built back up the PP account.

 

Not sure if the mic is off-axis really. How off does it have to be? Up, down, sideways?

 

The vocal mic is what's producing the feedback. The amp's not howling...I meant when I place the amp behind the vocal mic it gives me even less gain to work with before I get feedback problems.

 

The places will be playing barely have enough room for our bluegrass 4-piece band much less when we start gigging with drums.

 

Aside from things I can do to help this, which I hope you'll advise me on, does anyone have experience with that Shure 55 mic?

 

Thanks.

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Have you EQ'd the room to cut the feedback out? Any acoustical treatment in the room?

 

Audix OM7 is one of the top choices to feedback problematic rooms.

 

It takes practice, proper gain structure and EQ'ing to perfect feedback control. I can have a singer with an SM58 crouch almost to the grill of a Microwedge before it

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Hey Guys, I'm a nubile with sound equipment as I just started putting together my own system plus I've played mostly bluegrass for 20 yrs.


The room is about 300 square ft, carpeted, with no acoustic treatments. It's also my son's bedroom separated from the rest of the house by the carport. Ain't much but it's what we've got.


I know I should get a 32-band eq but just haven't built back up the PP account.


Not sure if the mic is off-axis really. How off does it have to be? Up, down, sideways?


The vocal mic is what's producing the feedback. The amp's not howling...I meant when I place the amp behind the vocal mic it gives me even less gain to work with before I get feedback problems.


The places will be playing barely have enough room for our bluegrass 4-piece band much less when we start gigging with drums.


Aside from things I can do to help this, which I hope you'll advise me on, does anyone have experience with that Shure 55 mic?


Thanks.

 

Cheapest fix and most reliable fix is turn down. I have to preach this over and over with my bunch because put them on a stage and all hell breaks lose with volume. :facepalm:

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A slightly relevant video to help understand some of the mic pickup pattern issues in relation to GBF:

 

 

On a basic level, with a hyper-cardioid mic you want to have the monitor in the 2 o'clock or 10 o'clock position, relative to the microphone. With a cardioid, you want the monitor in the 12 o'clock position.

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This sounds very much like an issue of too much volume for the room, in which case a new mic is not going to help anything.

 

Consider how much of the drums and guitar are going into the mic.

 

Consider that your goal is to make the vocal louder than the drums and guitar.

 

Then consider that as you turn up the mic channel, you are also making whatever else in that channel louder, including the drums and guitar.

 

Perhaps you will come to the conclusion that if, measured at the mic, the drums or guitar is as loud as your voice, then you will never be able to make the vocal louder than the drums or guitar.

 

But, of course, that is just my reasoning. Others come to different conclusions.

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A slightly relevant video to help understand some of the mic pickup pattern issues in relation to GBF:



On a basic level, with a hyper-cardioid mic you want to have the monitor in the 2 o'clock or 10 o'clock position, relative to the microphone. With a cardioid, you want the monitor in the 12 o'clock position.

 

 

Ok. Good tip and video reference there. Thanks.

 

We're trying not to be too loud believe or not. My son plays in his church youth band and has been working on his dynamics for several months and he uses VF 8D's which are very light.

 

Any rec's on an decent equalizer in the weekend warrior budget level (not Behringer level stuff, but more along the QSC/A&H line)?

 

How about auto feedback busters?

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Without being there it's hard to say what is happening. But if you need an EQ with that system (just for rehearsal) I would guess you're too loud - but as I said I'm not there, maybe you're not loud and there's another issue.

 

An EQ would help of course but.... for instance, I just used an HPR 122i last night as one of four monitors (ten piece band). I did not have an EQ on it and it was pretty loud.

 

So I'm guessing that because of the room size, reflections and band volume, you are louder than the room will allow. You can EQ out a few frequencies but after four or five cuts the volume will suffer such that you will want to turn it up again and.... you get the picture.

 

Feedback occurs when the source from the speaker appears at the mic as loud as the original source (or something to that effect - look it up).

 

Anyway, DBX makes some functional affordable EQ's such as the DBX 231.

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As far as the "Feedback Busters", I've used a pair of Behringers for a few years and my conclusion is they work OK, but I don't use them for any musical project that really matters. I reserve them more for public speeches, auctions, things that are not that critical to the ear. If speaker placement, etc.... don't work, I'd rather use a dedicated EQ.

 

TW

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I'm surprised no one in this thread has mentioned proper gain-structure.

 

Try this next time you plug-in your mic; set your mic channels' gain 'til it tickles the red LED, and then' crank the gain back about 6-9dB.(probably 9-10 o'clock?) Control your volume with the channel fader. Let me know if that works.

 

Also, are you using FX in that small room?

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I'm surprised no one in this thread has mentioned proper gain-structure.


Try this next time you plug-in your mic; set your mic channels' gain 'til it tickles the red LED, and then' crank the gain back about 6-9dB.(probably 9-10 o'clock?) Control your volume with the channel fader. Let me know if that works.

 

Amp attenuators can do wonders for gain structure. :idea:

Also to Pater as far as EQ recommendation DBX most affordable quality built EQ Also Rane and Ashly 31 band EQ if you have budget. Each monitor send needs it's on EQ so if your running a 2 separate mixes then a Dual 31 band would be more appropriate.

Come back once purchased and folks here will step you thru ringing out process.

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Probably your biggest limiting factor is your small room size. Your best bet is to turn down the band to match the vocal level you can comfortably achieve. You can spend a lot of time and money but you probably won't make the situation much better.

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Now, you listen here you young whipper-snappers (Don & Andy) :poke::lol::lol:

 

You're undoubtedly both right, however, let me tell you about a recent experience running sound for one of our jams.

 

Just a few weeks back, one of the guys here (I don't recall who) posted about working with a "high-profile" board engineer. The poster was surprised to see that the BE had his vocal mic gains set at approx 9:00 o'clock, and despite the fact that the performing groups' lead singer would wander around the stage, and out in front of the mains into the audience, resulted in zero feedback.

 

OK, so I decided to try that for myself. Drummer(acoustic kit), bass-player,and electric-guitar. Room size was approx 12'x20'. Drummer in the middle, and the bass and electric guitarist facing each other across the front of the drum-kit.

 

We used one PA speaker for the vocals (2 mics for the bass-player and lead-guitarist). The bass-player had the PA speaker stand-mounted (NX55P) just off his left shoulder, maybe 2-3' away. His vocal mic (SM-58) was forward of the speakers' grille-plane by a foot or two.

 

Room volume was quite loud, but not excessively so. (balanced with acoustic drum-kit) I set the gain on that vocal mic channel to roughly 10 o'clock (SoundCraft EFX-8). ZERO feedback,,, even when one of the guys unexpectedly grabbed the mic-stand, and moved directly across the front of the speaker, and planted the stand maybe 5' in front of the PA speaker, facing 90 degrees away from the speaker. (parallel to grille).

 

The room volume was such that a bit of instrument bleed was coming thru the mics, but again, no feedback. Zero, Zip, Nada. The sound was bang-on. The guys raved about how good it all sounded, and now the guys are wanting to practice every weekend, despite some having to drive 90 miles or more to attend.

 

The next day, several neighbours a few hundred yards down the road, told us how much they enjoyed the music, so it was reasonably loud to be sure. Mind you, it was a quiet rural area. :rawk::badump::rawk: We had a blast.:thu:

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Now, you listen here you young whipper-snappers (Don & Andy) :poke:
:lol:
:lol:


You're undoubtedly both right, however, let me tell you about a recent experience running sound for one of our jams.


Just a few weeks back, one of the guys here (I don't recall who) posted about working with a "high-profile" board engineer. The poster was surprised to see that the BE had his vocal mic gains set at approx 9:00 o'clock, and despite the fact that the performing groups' lead singer would wander around the stage, and out in front of the mains into the audience, resulted in zero feedback.


OK, so I decided to try that for myself. Drummer(acoustic kit), bass-player,and electric-guitar. Room size was approx 12'x20'. Drummer in the middle, and the bass and electric guitarist facing each other across the front of the drum-kit.


We used one PA speaker for the vocals (2 mics for the bass-player and lead-guitarist). The bass-player had the PA speaker stand-mounted (NX55P) just off his left shoulder, maybe 2-3' away. His vocal mic (SM-58) was forward of the speakers' grille-plane by a foot or two.


Room volume was quite loud, but not excessively so. (balanced with acoustic drum-kit) I set the gain on that vocal mic channel to roughly 10 o'clock (SoundCraft EFX-8). ZERO feedback,,, even when one of the guys unexpectedly grabbed the mic-stand, and moved directly across the front of the speaker, and planted the stand maybe 5' in front of the PA speaker, facing 90 degrees away from the speaker. (parallel to grille).


The room volume was such that a bit of instrument bleed was coming thru the mics, but again, no feedback. Zero, Zip, Nada. The sound was bang-on. The guys raved about how good it all sounded, and now the guys are wanting to practice every weekend, despite some having to drive 90 miles or more to attend.


The next day, several neighbours a few hundred yards down the road, told us how much they enjoyed the music, so it was reasonably loud to be sure. Mind you, it was a quiet rural area.
:rawk::badump::rawk:
We had a blast.
:thu:

 

I did a 3 day metal festival this weekend, gains were probably around 9 - 10 o'clock. Everyone raved about the sound on stage, being able to hear everything, didn't feed back once through the 3 days. Sounded great out front. These guys were all over the stage with the handheld mics, pointing them at the crowd, dropping them to their sides etc etc. A reasonable stage volume does wonders for reducing feedback...

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Guys, thanks for all the great suggestions here.

 

I might have inadvertently had the reverb on the vocals, so I will definitely cut that off.

 

I will stress to my son that we've got to try to cut the volume down considerably, even though I swear we're not nearly as loud as a band I rehearsed with a couple months ago. They're not headbangers either by any means, but rather guys in their 50's playing some R&B classics and blues. I thought I'd be deaf after leaving that.

 

I'm going to make sure I have the monitors in the null position of the mic.

 

I have some basic questions about gain structure. Since the QSC K12s are powered they have their own gain control. So, how should I set up the gain since both the mixer and the speakers have controls?

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I'm with Andy and Don, gain structure doesn't really affect feedback.

 

A gain knob and a fader both are ways to get volume. If you use them incorrectly you can suffer a noise penalty but all the microphone cares about in regards to feedback is when you break unity. When the sound reaching the microphone from the speakers is loud enough it WILL feedback, it doesn't matter how your gain is set up, it's physics.

 

Get your lips up on the mic as much as possible, do what you can to reduce the gain needed on the mic.

 

Place the speaker so it is mostly in the null of the mic and also look at how the sound might bounce around the room and look-out for that.

 

Try to get other loud sources (drums and guitar) out of the vocal mic as much as possible

 

If you still need more start EQing, you should only need to hit 2-3 frequencies tops, if you need more than that then we have to look at expectations. Turn the volume up until it just starts to ring a little and then find that frequency and notch it just a little bit, do this a couple more times and you should have plenty of gain.

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Get your lips up on the mic as much as possible, do what you can to reduce the gain needed on the mic.


 

This helped a lot in our situation. When I set-up the mics, the vocalists had to almost kiss the mic in order to be heard properly, even requiring them to raise their voices for louder passages.

 

Regarding "ringing out" the monitor, I didn't have time to do that in the jam I described earlier. It was a quick & dirty set-up. I had no 31-band EQ with me. We're hoping to get together again soon, so we can properly set our levels for future jams, including mic'ing the drum-kit. That's a ways off yet however. I won't be buying a drum mic kit 'til sometime in February. For now, I have the overheads, and a couple of SM-57's. Hoping to pick up the Sennheiser e902/904 drum-kit mics.

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Bobby (and stratguy),

 

I'll repeat what Don and Andy stated: gain structure has NOTHING to do with feedback. It affects signal/noise ratio. Overall gain is what matters. A given system in a given state can accept a given signal power before it becomes unstable. How you arrive at that power is irrelevent.

 

If your mixer is changing the EQ as gain and fader settings changes, that's probably why you perceive greater volume in one configuration than the other.

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With some pickup patterns and some mics the proximity effect can be quite strong when you get right up on the mic, my solution was to always get up on the mic and only back off for dynamic effect if needed. Then listen to how the volume and proximity effect differ and make it part of my sound, use it to my advantage. It takes some work but it can do wonders.

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