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Feedback in vocal monitors

supermonkey

supermonkey

Mar 15, 2004
368
1
Atlanta, GA
www.andytegethoff.com
#1
My band(s) practice in my basement, which is a medium-sized room, suspended ceiling and tile floors, with some very mild treatments (carpets, egg crates) to control reflections just a bit while still keeping things fairly live-sounding.

I use a cheap little Crate 4-ch mixer-amp w/ 2 12" wedges for monitoring vocals. As long as we maintain a reasonable volume level, this works OK. But if we get loud at all (which several of my bands pretty much always do) the vocals get drowned out easily. And I can only coax so much gain out of the system before inevitable feedback.

The system, all things being equal, is technically loud enough to serve my purposes. But the feedback is a deal-breaker. I have to completely cut each channel's 2-band EQ plus master 3-band EQ on the mixer in order to get rid of feedback at various ranges. And even at full cut, I can't simply increase levels until vocals are audible because the squeal will kick in. So I'm left with very flat, muffled, and relatively quiet vocals. I've zeroed things out and reset them, tried to get an EQ profile that wasn't crap at a good volume. But it always ends up pretty much the same.

For the record, I ultimately feel that we should all just play quieter, and this wouldn't be a problem. But since this is the real world and I work with drummers & guitarists, I already know where that idea will end up..... :ninja:

So, I'm interested in the TB community's ideas for potential solutions. FWIW, I'm already thinking of the following ideas:
1) Add a graphic EQ so I can notch out feedback freq's manually. From what I've encountered in the past, having tighter control over individual freq's might help me cut out the feedback more effectively w/o destroying sound quality.

2) Add a feedback exterminator to kill the feedback semi-automatically. Don't know ANYTHING about these boxes, other than the fact that I have feedback that needs to be exterminated, and the name says that's what they do...

3) Reconfigure everything and monitor vocals through headphones. This was my drummer's idea. I could run the vocals into another mixer I have, take the outs to my headphone amp, and distribute vocals for everyone that way.

Any thoughts? Experience w/ a Feedback Exterminator? Anybody do live monitoring w/ headphones?
 
#2
supermonkey said:
So, I'm interested in the TB community's ideas for potential solutions. FWIW, I'm already thinking of the following ideas:
1) Add a graphic EQ so I can notch out feedback freq's manually. From what I've encountered in the past, having tighter control over individual freq's might help me cut out the feedback more effectively w/o destroying sound quality.
Click to expand...

1) Get a good parametric instead, and never look back! Does your board have an insert point or pre out/power amp in config available?

As far as feedback exterminators go, they tend to work best if you manually set most of the filter bands (see #1), then leave a few in 'roving' mode. They work pretty well in many cases used this way.

Are you totally dialed on mike placement relative to the monitors? I see people all the time with avoidable problems caused by poor positioning.
 
#3
Parametric EQ - check.

The mixer amp is somewhat basic in terms of connections. It does have an FX loop, though.

And would you categorize the feedback exterminator as "either/or" or "both/and" with the EQ?

I think I'm good on mic placement. They're off-axis with the speakers, and since I have the floor wedges the mics aren't really in the same plane as the speakers. That said, I'm much more experienced with recording than with live sound engineering. So if you have any tips there, I'm all ears!
 
#4
supermonkey said:
And would you categorize the feedback exterminator as "either/or" or "both/and" with the EQ?
All the ones I've worked with have manually settable parametrics as part of the feature set, but the downside is that you have to go through a menu to set 'em. That's when you're hoping that the roving filters get to the offending frequency before you have to do it yourself.

IME a well implemented parametric will get you as far as you're probably going to get in most cases. I run 4 monitor mixes at the local club (two Ashly parametrics, two 31 band graphics), and feedback issues are really rare unless I'm trying to put vibraphone on top of a hip-hop mix, or something like that. And yes, I have actually had to do that!:help:
Click to expand...
Click to expand...
 
#7
Before going all Bose L1 my band used to have the typical set up for a rock band at rehersal. Drums and half stacks pointing out forward, a PA just for vocals and two monitors just for vocals.

The PA had enough power, but at a garage sized rehersal space it could not compete without feeding back with the monitors set up, as usual on the floor.

The only cure I found was putting the monitors up on stands at head level as side monitors. The best positioning was To have one in the forward left corners and facing right, and one in the back right corner and facing left.

This made the vocal easily heard by me standing and singing center stage and easily heard by the band. So, we could all hear at rehersal at a high volume.

However when people came to listen it was hard for them to hear the vocal if they were sitting on the coach in front of us because they were ear level with the halfstacks and the drums. So, only if they were standing up and in front of where I was singing and could hear, could they hear the vocal. So, it was fine for our rehersal but sucked for people who came to our rehersal.

Also, make sure you are carving frequency for feedback right. First turn all the frequencies in the eq fader off. Position your system as you are going to. with the mic where it goes. Now turn the volume all the way up. It won't feedback because all the frequencies are turned off.

Now take each frequency slider and move it up. If it feeds back it either needs to be cut down or cut out all together. Do this one at a time with each frequency. Now your system is optomized just for this room, this needs to be done for every room and should be done each practice. Even in the same room, things change slightly over time for a variety of reasons.


Also, look into feedback mics that are good for loud bands and good at feedback rejection. Most bands default to sm58's, which although a good souding mic, is not that great at feedback rejection. I hear good things about the audix om7 ,if you have the mic pre to drive it I hear it's very hard to make feedback and is specifically made for loud bands.
 
#9
ric1312 - thx for the advice; your setup doesn't quite match mine in a couple of ways, but your feedback zapping instrs. will be useful.

CincyBassMan - I have some egg crates up along certain walls, but not everywhere. I can try to mount some more absorption materials. Thx!

And again -- if anybody has mic placement tips, by all means let them fly.
 
#10
Just had a thought. What is your mic tecnique like?

Some singers back off the mic a couple of inches or more. All this does is lose the pickup for your voice. The only mics that you should be this far away from are studio condensors.

To get best gain before feedback make sure your lips are lightly touching the grill. This way you get the best gain before feedback and get full use out of whatever amount of gain you have.

When you see those dufus's on american idol singing and pulling away from the mic by a foot, it just shows they don't know what the hell they are doing. .........you can do a fade off just using your voice and not pulling away.

The only time you should ever have to back off is if you have a lot of gain on a mic and you are singing very loudly for a short burst and it would cause the mic to clip. Even then, with a good mic even just 3 inches is enough backing off.

Another thought, and this is harder to do with a live acoustic drummer, build up the bands volume around the volume of the vocal.

As a last ditch thing, if you can't hear good and the volume is up their, just wear ear plugs when you sing. Even though the vocal isn't heard great out in the room, with ear plugs in it's like having in ear monitors. I used to have to do this all the time playing out in metal/rock bands where it was hard to get a loud monitor to cut through guitards with halfstacks and ape like drummers bashing on a drum set. Makes it much easier to sing. In fact I often used ear plugs in situations where there were no monitors.
 
#11
I vote for the extra EQ insertion and although I dig parametrics it would depend a lot on how many groups or center freq's it gave you control over. And for most people with limited experience, graphics are easier to understand and operate.

Try and always be negatively EQ-ing, at least at first.

Memo to your band:

When you've got the most out of the system, no matter what the source of the problem, that's it, there ain't no mo' and it's time for the band to turn the $^$# down!

Bonus question:

If you had only 2 EQ's, one being say a 7 or 8 band EQ and the other a 31 band, which one would you put on the monitors?

JKT :bassist:
 
#12
JKT said:
I vote for the extra EQ insertion and although I dig parametrics it would depend a lot on how many groups or center freq's it gave you control over. And for most people with limited experience, graphics are easier to understand and operate.

Try and always be negatively EQ-ing, at least at first.

Memo to your band:

When you've got the most out of the system, no matter what the source of the problem, that's it, there ain't no mo' and it's time for the band to turn the $^$# down!

Bonus question:

If you had only 2 EQ's, one being say a 7 or 8 band EQ and the other a 31 band, which one would you put on the monitors?

JKT :bassist:
Click to expand...

The monitors? Seems those are the most likely to feedback because the mic is aimed at them.
 
#13
You would find that an active system with large format midrange horns
2" throat crossed tight at 800 with efficient bass drivers in good ported cabs facing straight at you from corners, a reasonable digital system controller.
A quality 150+ watts RMS per channel into 16 ohms amp for the Horns the only passive crossover component you will require is a 40uf poly prop cap if the driver is sixteen ohms in series with the diaphragm to protect from DC and mains hum, switch pulses etc and then as big an amp as you can get for the bass drivers, you wont blow them in a small room unless you run trigger kicks or something like that. parametric is better than graphic for room eq, I think feedback suppressors are a sure way of making your PA worse than if you eq'd it, If you have any talent that is. Its for people who work in karaoke bars for faffs sake.
Where people cant sing loud enough to pull the skin off a rice pudding
and nobody knows anything about audio engineering and usually have
beringher or some **** like that written on it.
Anyway use sm 58's facing any other direction than down the horns
and get a good vocal tone with the eq on whatever desk you got,
see if you can improve it with the system control'r most have eq built in as well as crossovers and limiters these days. then turn it up till it
just doesn't ring with feedback.
Passive systems tend to have very bad beaming of various frequencies
due to not wishing to make a disappointingly power sapping design any worse by attempting attenuating them and small monitors usually don't have useable midrange horns, they don't go low enough to pick up that efficiency dividend. Also these days of light weight idiot proof everything they tend to be quite heavily protected with bulb fusing etc. this is all very compressive and reduces feedback headroom by the exact number of db it attenuates.
Many small monitors horn units do not even have a properly designed phase plug as one would expect in a solid midrange driver design.
JBL 2445 on a 2380a is the old industry standard.
Old dual 1.4" Altec's with 500 hz multicellulars are very very good and surprising in small spaces, go on blow your head off with 100 watts!. Go and raid an old closed cinema.
If you find any old Vitavox drivers and horns there mine! all mine:bassist:!
 
#14
+1 to the parametric.

If the problem at the end of the day is that the band just loves to rehearse LOUDLY and some players don't care about burying the vocals, then you might consider running a all-vocal (or mostly vocal) mix through a headphone amp.

This way, your singers can hear themselves to harmonize. IME, even with closed ear headphones, they'll still hear plenty of the amps and drums. (In fact, with very loud rehearsal rooms, the closed ear headphones will reduce the dBs, so you can save your ears a little bit.) If necessary, you can feed a little bit of room mic or instrument mics into the headphone mix.

BTW, non-singing players who don't want to wear headphones don't have to. Stick a floor monitor back by a non-singing drummer, for example, so he can get vocal cues. It doesn't have to be very hot, and it's not likely to feedback through the monitor system if there isn't a vocal mic nearby.

It's not the best way to practice; but if the players won't bring drum and amp levels down, it at least lets everybody hear what they need to to make practices productive.
 
#18
The cheap feedback supressors do a pretty decent job but they are quite stupid, don't expect miracles from them. I get the best result by setting the filters to roaming and ringing the monitors before the band starts. You'll get some squeals when the band starts up and the box reacts but nothing major. If you know your monitors have a hotspot at 3k for example, set one of the filters to parametric and manually tame it. I assume you are running 4 mics, if the mixer has inserts on each channel pick up a cheap 4 channel gate/expander (/compressor) and gate the poo out of each channel, so the vocalist has to be right on the mic. The more open mics the less gain before feedback so properly set gates are your friend. Make sure your monitors are placed according to the pickup pattern of your mics too. It may also pay to check the mics, if one has been dropped that may contribute to the problem.
 
#19
derrico1 said:
+1 to the parametric.

If the problem at the end of the day is that the band just loves to rehearse LOUDLY and some players don't care about burying the vocals, then you might consider running a all-vocal (or mostly vocal) mix through a headphone amp.

This way, your singers can hear themselves to harmonize. IME, even with closed ear headphones, they'll still hear plenty of the amps and drums. (In fact, with very loud rehearsal rooms, the closed ear headphones will reduce the dBs, so you can save your ears a little bit.) If necessary, you can feed a little bit of room mic or instrument mics into the headphone mix.

BTW, non-singing players who don't want to wear headphones don't have to. Stick a floor monitor back by a non-singing drummer, for example, so he can get vocal cues. It doesn't have to be very hot, and it's not likely to feedback through the monitor system if there isn't a vocal mic nearby.

It's not the best way to practice; but if the players won't bring drum and amp levels down, it at least lets everybody hear what they need to to make practices productive.
Click to expand...


This is what my drummer has been suggesting. I think I will set it up to give it a try, but honestly I'm not all that excited about the prospect. Practicing w/ ear goggles seems extremely lame. :rollno:

But it might work well. We'll see.
 

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