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[hfc7713]

I hope someone here can help me out......I am having a problem with live shows. I run the sound for a local band and I get a great FOH sound using SRX715's and SRX718's with plenty of headroom. However, I have a monitor issue (like most everyone else probably). We decided to go with powered monitors.  This is my issue.... with the gains and masters all set at unity or below and the EQ's on the monitors set level, I only have to turn the aux send up slightly and the signal is quite hot and the monitors feed back. If I cut back a small amount, they are too quiet. The aux send is far too sensitive. At the weekend I had the gains and masters on the monitors really low i.e. gain at 1 or 2 o'clock and master at 3 o'clock. The aux sends were at not even 2 o'clock and I was scared to even move then because when I did, either I got the evil eye from the vocalists because they couldn't hear themselves or I got feedback. One more thing, I have the monitors going through a DBX 31 band EQ which I used and was able to pull out a couple of frequencies to help but these settings are crazy low and I am not sure why.....

[hfc7713]

Sorry..I just realized I posted this on the recording forum....oops..s/b live sound

[Fletcher]

No struggle - a lot of us have some time in that rodeo.

All I can say from your description is that you need to spend a bit more time with the 31 band and work on the tuning / positioning of the wedges.  We've probably all been there [in the 80's a rather famous rock star at the time winged a mic stand at my head when I was doing monitors for him... he was pissed that I had the mic muted every time he stuck the mic into the throat of a JBL 2" driver... it was the 80's - you had to be there].

Peace

[hfc7713]

Thanks for the suggestions Fletcher -I'll mess around more with the EQ and move the wedges. I love the story....Yeah the 80's......Good times!!!

[Fletcher]

How high is the ceiling over the stage?  Is there a backdrop behind the stage? [as in cloth, as in something that will absorb high and upper midrange information?].

In most clubs those two things [along with "baseball" / "trucker" hats] that will get you into trouble quickly.  In those situations tuning and wedge placement are really critical... and it helps if you can let the artist(s) know the struggles you're having so they are aware that if they move wrong they can get into trouble.

One thing I have found help greatly in a difficult room is to reassure the artist that your sole goal is to provide them with the things they need to do the best performance possible... but these are the limitations of the system and the venue... so please bare in mind that while I'm doing the best I can for you -- there are physical limitations [as in limits imposed by physics] that will come into play.

Hope that is of some assistance.

Peace

[John Roberts {JR}]

yup, you're likely to get more responses over in the Live sound reinforcement forum.

Feedback and monitors are like spaghetti and meatballs (they go together).

The short answer is when loop gain of sound from monitor speakers picked up by the vocal mics, circle the loop with more than unity gain they will run away.

In practice there will be hot frequencies as a function of (acoustic) path length, and that relation to signal wavelengths wrt constructive addition. For a well behaved system (flat monitor speakers, voal mics with good off axis rejection, etc), you should be able to get decent monitor level before feedback by knocking down a handful of feedback modes. A 1/3 octave GEQ is commonly used because they don't make 1/6th octave, while you can use a few parametric EQ and get away with narrower notches.

GEQ are more popular because they are easier to operate in "guess that feedback frequency" mode. 

JR

[Patrick Tracy]

We decided to go with powered monitors.

Brand and model please. First thing that popped into mind was the Line/Mic level switch on JBL EON powered speakers. If it's set to Mic then it would explain the excess gain.

[Dinogi]

Brand and model please. First thing that popped into mind was the Line/Mic level switch on JBL EON powered speakers. If it's set to Mic then it would explain the excess gain.

You got that right Patrick.
I have done the exact thing to myself once or three times.
I never use the mic setting but I always check that #@%!! little button before firing them up. Every once in a while I find it mysteriously in the wrong position. My wife thinks we got ghosts. But thats a story for a Halloween haunted studio thread. Hey, I just hijacked a wrong forum post. Is that a record or something?
olduncledinogiammattei

[Jim Williams]

No struggle - a lot of us have some time in that rodeo.

 We've probably all been there [in the 80's a rather famous rock star at the time winged a mic stand at my head when I was doing monitors for him... he was pissed that I had the mic muted every time he stuck the mic into the throat of a JBL 2" driver... it was the 80's - you had to be there].

Peace

I had a similar experience with Crocker Dwight Yoakum. He used to throw mic stands at AE's if he didn't get his "sound" right. That crew lived in fear. Great working enviroment. They offered me that gig but I turned it down, I need some sanity in my life. BTW, that stupid cowboy hat forced us to reset the monitor EQ, we would put a crew guy up there and stick that hat on him to tune the 31 band EQ or it would howl!

[hfc7713]

Thank you for all your suggestions everyone. My confession at this point to Patrick who asked make and model would be to admit that because I spent all my money on FOH, snake, good quality cables and rack equipment, I had to buy Harbinger AP12's and 15's for monitors. I know you probably hate them but the sound seemed perfectly adequate for monitors but it seems they might not be very forgiving when it comes to feedback problems. I will get better quality ones when money allows but till then I am stuck and will have to just tweak what I can...Thanks again...

[jamesp]

I had to buy Harbinger AP12's and 15's for monitors.

They're made by Soundking in China and the Studiospares own brand equivalents that I've heard have been perfectly usable although a bit bass heavy.

As others have said, the first thing I would check is the mic/line setting although, if the controls are arranged so that 12 o'clock is the half way setting, using them at 2 or 3 o'clock isn't going to be unusual. In fact, as a starting point, I would set them to their half way setting (12 o'clock?). The other thing that I would check is that you aren't using any compression on the vocals as this will make it harder to avoid feedback. If you feel that you absolutely must use compression then use the minimum you can get away with.

A friend of mine uses similarly cheap speakers on monitors but regularly gets work from some very big names. His secret is to make the monitor mix the most important thing to get right in a soundcheck - probably 80% of his soundcheck time is spent on monitors. The artists love this and, consequently, he gets the work.

James.

[Patrick Tracy]

Thank you for all your suggestions everyone. My confession at this point to Patrick who asked make and model would be to admit that because I spent all my money on FOH, snake, good quality cables and rack equipment, I had to buy Harbinger AP12's and 15's for monitors. I know you probably hate them but the sound seemed perfectly adequate for monitors but it seems they might not be very forgiving when it comes to feedback problems. I will get better quality ones when money allows but till then I am stuck and will have to just tweak what I can...Thanks again...

I've spent a lot of my time using cheap gear to good effect so I won't be too critical.

I think you just need to set your board to what's right for it and lower the gain on the monitors to make operating the board convenient. Make sure you're using the line input and not one of the mic inputs. Set the main level to about 7 (about 2 o'clock) and set the monitor volume with the line input's level control after you've gotten proper signal levels at the board.

Because of the RCA inputs on the line input it wouldn't surprise me if it was set up for -10dBV rather than +4dBu. That would make it pretty sensitive to a +4 signal and would require you to lower the gain significantly.

[John Roberts {JR}]

For gain before feedback, polar frequency response over the vector common between vocal mics and monitor speakers is what matters. You can only EQ the entire speaker or entire mic channel, so if the mic and speakers don't play together nicely in this off axis vector this will affect the max vocal mic gain you can realize without feedback or severe equalization that can degrade vocal feeds and/or monitor mix quality.

Professional monitor speakers and microphones account for this (as well as physical location of both mic and monitor speakers in use).

It seems to me monitor speakers could be made with a mic stand built in, and a special purpose dedicated mic provided to standardize several of the variables and reduce inexperienced operator pain and suffering. While nowadays with wireless mics you have less control over precise mic location.

JR

 

[hfc7713]

I might have been using the mic input now I think about it. Well, if I was, then that will be my first fix and hopefully help cure my problem. Haven't been able to use the same set up since the last gig but will use all the helpful info you have all given me next gig. Thanks again all....I really appreciate your time and expertise ..
Regards............