I'm the sound guy at my local church, and I've quickly realized a few problems I cant over with my inherited system. To begin Im using a Yamaha poweted mixer to drive the mains and a yamaha power amp to drive the monitors. My first problem is when I try to achieve unity gain, I can't figure out how to achieve it without getting massive amounts of feedback through my mics.(loud screeching sound) Also the keyboard is a big problem for me, it constantly peaks and recently caused two speakers to blow. It peaks constantly but especially when the keyboard player plays low notes. Ive tired lowering the gain,turning down the keyboard output, bringing down the fader, and changing up the eq nothing really worked. The final thing is my stage monitors, they work fine but I have to constantly be on edge with them because anytime pastor gets in range of them they will screech. I turned down the sensitivity on the amp and turn down the monitors but it gets too low no matter how I try to gauge it. Also were bringing in a new bass player so how can I prepare for him? Im really trying hard at this and have replaced equipment and did so much research to make the system better. Its better than I found it but still very far from perfect.
Mic feedback causes.
- Incorrectly set, insufficient or missing monitor EQ
- Incorrect type of mic... ex: omnidirectional lapel mic instead of cardoid(unidirectional)
Instrument input peaking(clipping).
- Signal too hot, insert a DI between the instrument output and board and engage the 10db or 20db pad.
Unity gain.
- That is a complicated topic but suffice it to say you have no hope of getting anywhere near full output form the system unless the above items are addressed, you may also have to add EQ to the FOH speaker systems and room treatments to dampen reverberations.
- Incorrectly set, insufficient or missing monitor EQ
- Incorrect type of mic... ex: omnidirectional lapel mic instead of cardoid(unidirectional)
Instrument input peaking(clipping).
- Signal too hot, insert a DI between the instrument output and board and engage the 10db or 20db pad.
Unity gain.
- That is a complicated topic but suffice it to say you have no hope of getting anywhere near full output form the system unless the above items are addressed, you may also have to add EQ to the FOH speaker systems and room treatments to dampen reverberations.
DI is short for Direct box, it contains an isolation transformer and other electronics to level match and isolate a source instrument from the PA. You will find these available at all price points and up to about the $200 price level you really do get what you pay for.. but you can get acceptable results at $100/ea for a passive DI from a variety of manufacturers.
Radial ProDI | Sweetwater.com
Radial ProDI | Sweetwater.com
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DI boxes tend to be solid and rarely break. I'd save some money and buy 2nd hand, unless budget just isn't an issue.
Anyway.
On the desk, you've got an Aux/Monitor send for each channel. Turn the pastor one right down. You were feeding his mic to the monitors, which isn't needed. Anything not needed in the monitor mix shouldn't be there, as its just gonna make it that bit easier to get feedback.
You need as many 31-band graphic EQs as you have amplifier channels. So if you've got two monitors that each have their own monitor mix, you'll need an EQ on each one. EQs go between the mixing desk and the power amplifier.
Next up, download a spectrum analyser app. I use Audio Tools, but it costs a small amount. You want one that gives you a peak frequency readout.
Before everyone turns up, turn down all the desk outputs (main faders, Aux sends) get all the mics that're going to be used, set gains correctly, and then SLOWLY increase ONE of the outputs. Set the spectrum analyser running. Keep increasing the volume, and you'll just start to get feedback. The app will tell you which frequency is ringing. Go to the correct EQ, and push the nearest slider for that frequency all the way down. The feedback should stop. Push the volume a little more, you'll get more feedback at a different frequency. Check the app, push the slider on the EQ.
Remember, when you start getting feedback, it can quickly run away with you. Keep a finger on the dial, and only let it ring long enough to get a reliable readout on the app. You risk damaging the speakers if its just left to ring forever.
Repeat that until you've taken out 4 or 5 frequencies. Drop the volume a nudge, and then find a mic and talk into it. Is the thing you've been working on loud enough? - you want to be sure of this, as someone might request a load more of their mic in the monitors, so account for that and make sure you can push louder without having to worry.
If its loud enough, repeat the process with the next desk output.
If its not loud enough and you're still getting feedback, take out a few more frequencies. You don't want to go too far on this - the more frequencies you take out, the worse the monitors will sound (they'll be louder though).
Graphic EQs can be had cheaply. A Behringer one will do the job just fine, and their more recent ones have FBQ, which lights up the slider that's showing feedback - very useful.
HTH
Chris
Anyway.
On the desk, you've got an Aux/Monitor send for each channel. Turn the pastor one right down. You were feeding his mic to the monitors, which isn't needed. Anything not needed in the monitor mix shouldn't be there, as its just gonna make it that bit easier to get feedback.
You need as many 31-band graphic EQs as you have amplifier channels. So if you've got two monitors that each have their own monitor mix, you'll need an EQ on each one. EQs go between the mixing desk and the power amplifier.
Next up, download a spectrum analyser app. I use Audio Tools, but it costs a small amount. You want one that gives you a peak frequency readout.
Before everyone turns up, turn down all the desk outputs (main faders, Aux sends) get all the mics that're going to be used, set gains correctly, and then SLOWLY increase ONE of the outputs. Set the spectrum analyser running. Keep increasing the volume, and you'll just start to get feedback. The app will tell you which frequency is ringing. Go to the correct EQ, and push the nearest slider for that frequency all the way down. The feedback should stop. Push the volume a little more, you'll get more feedback at a different frequency. Check the app, push the slider on the EQ.
Remember, when you start getting feedback, it can quickly run away with you. Keep a finger on the dial, and only let it ring long enough to get a reliable readout on the app. You risk damaging the speakers if its just left to ring forever.
Repeat that until you've taken out 4 or 5 frequencies. Drop the volume a nudge, and then find a mic and talk into it. Is the thing you've been working on loud enough? - you want to be sure of this, as someone might request a load more of their mic in the monitors, so account for that and make sure you can push louder without having to worry.
If its loud enough, repeat the process with the next desk output.
If its not loud enough and you're still getting feedback, take out a few more frequencies. You don't want to go too far on this - the more frequencies you take out, the worse the monitors will sound (they'll be louder though).
Graphic EQs can be had cheaply. A Behringer one will do the job just fine, and their more recent ones have FBQ, which lights up the slider that's showing feedback - very useful.
HTH
Chris
A lot of good advice in Chris's post. DI boxes can be had for reasonable money.
There are a lot of very useful tips in the mixer manuals, with the Mackie series (I know you have a Yahama) being very good at setting out the basics of setting gains for each channel, EQ'ing, signal routing etc.
Another useful resource may be:
How to use an audio mixer (soundboard) : From the top: Gain (Trim, Sens)
There are a lot of very useful tips in the mixer manuals, with the Mackie series (I know you have a Yahama) being very good at setting out the basics of setting gains for each channel, EQ'ing, signal routing etc.
Another useful resource may be:
How to use an audio mixer (soundboard) : From the top: Gain (Trim, Sens)
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