Gain setting on PA?

[wayne8]

Our church has never had a real soundman but over the years there's been a few people that worked with it. I downloaded the manual (it's a Mackie SR24.4) and it said that if the OL light is lit continuously, the gain is too high. I plugged into the back of the board today and was using phones to set my EQ on the board for my guitar and I noticed the OL light was lit solid. The trim knobs (gain) on every channel were turned up to about 2 or 3 o'clock.

Now, if I understand this correctly, the gain needs to come down until the OL light only lights up occasionally when playing hard. Then you use the volume slider to adjust the volume. I tried that and couldn't get enough volume. So I think that means the volume on the power amp needs to come up to compensate, right? Volumes on both sides of the amp are at about 1:30 to 2:00.

I've always had trouble with the bass strings on my guitars through this system. No matter how much I turn up the bass, the bass strings sound really bright and almost distorted. I think maybe the gain is too high on the board and that's causing it.

My guitar is a Taylor 614CE but I've had the same issue with a Yamaha and two Gibsons.

[lschwart]

Originally Posted by wayne8

Our church has never had a real soundman but over the years there's been a few people that worked with it. I downloaded the manual (it's a Mackie SR24.4) and it said that if the OL light is lit continuously, the gain is too high. I plugged into the back of the board today and was using phones to set my EQ on the board for my guitar and I noticed the OL light was lit solid. The trim knobs (gain) on every channel were turned up to about 2 or 3 o'clock.

Now, if I understand this correctly, the gain needs to come down until the OL light only lights up occasionally when playing hard. Then you use the volume slider to adjust the volume. I tried that and couldn't get enough volume. So I think that means the volume on the power amp needs to come up to compensate, right? Volumes on both sides of the amp are at about 1:30 to 2:00.

I've always had trouble with the bass strings on my guitars through this system. No matter how much I turn up the bass, the bass strings sound really bright and almost distorted. I think maybe the gain is too high on the board and that's causing it.

My guitar is a Taylor 614CE but I've had the same issue with a Yamaha and two Gibsons.

Sounds like the input sensitivity on the power amp is set too low (and/or the setting on the mixer's main outs is too low) and someone has been turning up the input gains on the channels to compensate, causing those inputs to be driven into distortion. Check the main output level and the input sensitivity on the power amp. Turn one or both of them up, if necessary, depending on what you see. This will either allow the power amp to be driven to full power with the right level signal coming from the mixer. And are there EQ's, crossovers, and/or compressors involved? Make sure that the volume faders on the channels are set correctly too. A good starting point for these and the main mix output is usually around or a little below the "0" mark, but it all depends on how all the settings work together, and it's a balancing act that will get you the volume you need with minimal unnecessary background noise and no distortion.

It's also possible that the power amp and speakers you've got are inadequate for the levels you need, and if that's the case, you need to upgrade those parts of the system to get the levels you need without distortion.

And also make sure that you're using the right signal chains from your guitars into the channel inputs. I assume you've got the ES in your Taylor that allows you to use a TRS to XLR male cable into a mic input. The other guitars should probably go through DI's, depending on what kind of pickups they have. The wrong set up from the guitar to the mixer can also cause sound problems.

But, if funding allows or someone knows someone, the best thing you can do is to hire a good sound pro to come in once and set the system up properly for you for optimal gain. After that, you'll only need to worry about making adjustments for particular inputs from the basic starting point he or she sets up for you.

EDIT: having read Hunter's comments below, I realized that I didn't realize you were dealing with a powered mixer, so please ignore the parts of the above that assume you've got a separate power amp or amps! You probably don't need a pro for this either--assuming the system is indeed powerful enough for the room.

Louis

[zhunter]

You basically got it. That unit has essentially 3 volumes, the input trim, the channel slider and the main mix slider. Input trim is set as you stated, occasionally bumping the red light at input volume peaks. At that point a good place to start is with the main mix slider at 0 db. Then using the channel slider set your volume. If speaker volume is too low then go to the power amp and turn up. At 2:00 you should have some room left.

It is a process at this point where you adjust all of the channel trims to get occasional peaks and sliders to get a volume mix between the instruments. At 0 db on the main mix you have some room to go up or down depending on the needs of the room. Just keep in mind that bumping the main mix further with the power amp near the top can generate distortion on that end.

You can experiment too. Instead of starting with the main mix at 0 you could set it a little lower to give you more room to pump the overall mix volume if you have plenty of headroom at the power section. You could set your level on the peakiest instrument or the steadiest instrument. If the guitar is boosting for solos, you might want to allow for that and leave some headroom.

In summary, trim level is quality instrument signal driven, channel slider level is mix driven and final mix slider level is room volume driven.

Your basic grasp is good. Now you just have to play with it.

hunter

[zhunter]

Also ideally you want to get as much signal through each section up to the power amp to minimize signal to noise. That is make the PA noise quieter. So way too much volume with the final mix fader at 0 you might want to think about backing down the power amp and not the final mix fader. Places I play that little bit of noise doesn't matter too much but at least you can be aware of the principal.

hunter

[wayne8]

Okay, I appreciate the help. I'll give it a shot.

[ljguitar]

Originally Posted by wayne8

…I plugged into the back of the board today and was using phones to set my EQ on the board for my guitar and I noticed the OL light was lit solid. The trim knobs (gain) on every channel were turned up to about 2 or 3 o'clock.

Hi wayne...

Something I have to ask. When you plugged into the back of the board directly, did you use the same connection on the board (XLR) that would have been used if you are using a snake?

I am assuming for services you plug your guitar either into a direct box or preamp with direct box capability which then plugs via XLR cable into the snake on stage, which is feeding the signal to the mixer/board. Is that correct?

You need to replicate the chain using the same gear if you are going to attempt to set the board while sitting at the board. The output levels of your guitar with a guitar cable into the ¼" inserts will be different than with an XLR.

You may have tested it that way, but I could not tell by your posts.

[wayne8]

Hey Larry. Yes, I was using my Fishman Aura pedal into the back of the board. The only thing that was different was the snake was removed from the chain. Fishman Aura Spectrum pedal. It's also a D.I.

[mark neel]

gain structure is pretty much the most important element of sound assuming good equipment. as someone stated above sometimes it is worth a few bucks to get someone qualified to come in and do an original setup, then zero out, and let you do the setup. understanding that chain of events is something anyone using sound can benefit from. the Yamaha sound reinforcement handbook is probably twenty years old but any time I hire a new sound guy at our property I buy him a copy. fairly basic terms and layouts that cover all aspects, and while the equipment has changed the basic tenets of sound remain. good luck. and ps-a lot of times in churches, show rooms, etc., they have a set it and leave it policy. be the guy who gently leads them to the nirvana of consistent well executed sound :-)

[wayne8]

Is that Yamaha book fairly easy to understand? If an education gets done it's going to be me I guess and I have a hard time understanding a lot of the Mackie manual. If I can find someone else willing to spend the time to help, I think I could zero everything and start from scratch but I'd like to have an easy to understand resource in my possession first.

[Bobby1note]

Originally Posted by wayne8

Is that Yamaha book fairly easy to understand? If an education gets done it's going to be me I guess and I have a hard time understanding a lot of the Mackie manual. If I can find someone else willing to spend the time to help, I think I could zero everything and start from scratch but I'd like to have an easy to understand resource in my possession first.

The Mackie manual (like some of their products) is a joke.

If the channel-input gains are set at 2:00-3:00, they're probably waaay too hot. I just took a quick look at the manual, and "unity" gain is 9:00. You don't need to "blink" the input-gain lights,,,,,, what you need is, enough gain to eliminate the mic-channel's noise-floor (hiss). That would be the minimum starting-point. As it stands now (3:00 setting), you're probably clipping the input gain like crazy.

I have to go for the moment, but I'll be back in a bit.

[wayne8]

Thanks guys. You've been a big help. I'm going to tackle the job soon as I get a chance.

[Dr.Agave]

Originally Posted by wayne8

Now, if I understand this correctly, the gain needs to come down until the OL light only lights up occasionally when playing hard. Then you use the volume slider to adjust the volume. I tried that and couldn't get enough volume. So I think that means the volume on the power amp needs to come up to compensate, right? Volumes on both sides of the amp are at about 1:30 to 2:00.

You didn't mention if there was an equalizer or audio processors between the mixing console and the amplifier(s).

If so, it is possible that the loss is the result of drastic attenuation of equalizer filters or just the result of attenuation due to a gain control setting.

[jseth]

It's obvious what the issue is with that mixer/amp...

Google "Gain Staging" and read it! Do yourself a favor and get a grasp on this fundamental aspect of live sound re-inforcement... so many players DO NOT understand gain staging, and end up hating their sound, blaming the equipment or their pickup or whatever...

...when, per usual, it's OPERATOR ERROR that's the culprit!

[wayne8]

No, there's no outboard effects or processors between the mixer and the amp. Yes, thanks to you guys I've been reading up on gain staging and feel pretty confident I can do what needs to be done. Just waiting now for a good time to do it.