Gain Structure

[jackcu 0]

I was reading about clipping on another thread and it raised a few questions. I'd be interested to know what settings you use on each piece of equipment in the audio chain.

 

1. How much gain on the channel?

2. How much gain on the main mixer outputs

3. How much gain on the amp?

 

Here's my normal settings:

 

1. On the channel I usually have the fader set at the thick line (should correspond to 0db I think)

2. On the main output I have the fader set to light up 2 out of 4 of the red lights (+2db)

3. I have the amp set around 2 o'clock

 

Is this sensible or not - what does everyone else do?

 

Cheers,

 

Jack.

[Gary 0]

Its a difficult thing to advise upon as some mixer front panels and LED ladders are not calibrated exactly the same, nor share the same "channel curve" characteristics as each other.

 

For my own system (Denon DN-X1500 mixer), I always adjust the input gain knob so that the signal LEDs for that channel only bounce into the red, but never stay red.

 

The DN-X1500 offers three channel curves - sharp, normal. and soft. I have all the channel curves set to "normal", so that when the fader is halfway up, I get half the output, and if the fader is 10% up, I get 10% output. On this setting, I tend to keep the faders just over 3/4's of the way up.

 

My master volume, I use the same way as the channel inputs eg: The signal lives in the green, but occassionally bounces into the red momentarily.

 

All of the above is the same whether I'm in a large venue, or a small venue. What varies with venue size is what settings I have my amp controls on.

 

I might be right or wrong in the way I set all or any of the above, but I've never, ever lost or blown a speaker yet, or suffered from strained sound.

[jackcu 0]

On my Numark CM200 there are no LEDs on the individual channels, but they are about 75% up like yours. When all of the settings are as described I watch the lights on the amp. They very rarely go red, but when they do I back off the mixer a little. I'm sure I could drive them into the red more often, but I'd be worried. I have a limiter / compressor that I haven't used in the chain that I plan to use when I get the right case for the gear. I'm going to experiment with it this week as it should allow me to set it so that the amp never goes into the red but the sound is nice and beefy.

 

Anyone else got a view?

 

Cheers,

 

Jack.

[DJ Marky Marc 0]

Input gains on each channel I adjust depending on the level of each track im mixing thats why they are there....

 

so that when I push the fader up on the channel I dont get any nasty suprises with the level.......

 

main output from the mixer is used to control over al volume but never gets upto the point of there being red lights... infact it hardly ever gets upto the 0db level...

 

input gains on the crossover are set at 0db

 

output level on the crossover is also set at 0db

 

and input gain on the amps is set for 9 out of 10, basicly all the way up and then back a little bit.....

 

I havent found out how loud it all goes and dont want too...

[DJ SPARKO 0]

i use a 3 band eq with...

 

gain at 10, o clock

 

high at 2, o clock

 

med at 10, o clock

 

low at 2, o clock

 

each channel used the fader also set at the thick black line.

 

the main out on the mixer at 3, o clock

 

and the amp up full whack

 

these settings vary thoughout the night to adjust to what sounds good with different music i.e. a song with loads of base the low eq i will adjust to an appeopriate level set by ear

 

i beleive this to be a half decent setting??? http://www.dj-forum.co.uk/html//emoticons/533.gif http://www.dj-forum.co.uk/html//emoticons/smile.gif

[Dukesy 0]

I'm with Marky

QUOTE

Input gains on each channel I adjust depending on the level of each track im mixing

 

You can generally find a 'basic happy setting' but should always adjust channel gain to that of the source sound input level, either retarding or increasing that source input level to the 0db level as close as poss. If it peeks occasionally into the 'red' beyond 0db - no real harm will be done. But if the channel sound level is peeking into the 'red' all the time then it's only a matter of time when the cost of the 'damage' has to be reviewed!

 

So, in practice, you may find that modern CD recordings have to be 'retarded' a little on gain and bass eq than that of older recordings such as 50s/60s tracks.

 

Note that even if the master volume is not in the 'red' but the channel level is - damage can still be done.

[norty303 0]

QUOTE

Note that even if the master volume is not in the 'red' but the channel level is - damage can still be done.

 

I'm unsure by your statement here. Reds on amps is a 'bad thing' however reds on pieces of kit like mixers and outboard is usually only bad from a sound quality point of view.

 

Overdriving a channel will introduce distortion on that channel strips input stage and different desks/mixers behave differently. The master ouptut is (depending on accuracy) telling you the total output coming from the mixer, so even if the channel is massively overdriven, if the master is still showing green you aren't giving a massively over the top signal to the amp, just a distorted one.

 

A distorted signal will sound bad through the speakers but not necessarily do any damage. However, if you're driving the amp so that it clips and sounds bad then you WILL do damage.

 

Naturally, if you drive a channel so hard that you have to compensate by lowering the master then you are doing something wrong - which is really what gain structure is all about - and where we came in! :)

[Dukesy 0]

I'll amplify the statement (excuse pun) http://www.dj-forum.co.uk/html//emoticons/rolleyes.gif

 

QUOTE

A distorted signal will sound bad through the speakers but not necessarily do any damage.

 

Long-term, even if the master volume on the mixer is not in the clip-zone area (red), you would agree that a distorted sound signal is still getting to the amp.

Pushing this 'distorted sound signal' via the master volume is, and can not be a good thing.

 

The amp will work harder. The amp will get hotter. Long-term damage to both amp and of course the speakers is thus preventable.

[norty303 0]

No, distortion just 'sounds' bad. Your amp can't tell the difference between a distorted signal at -3db and a clean signal at -3db apart from the distorted signal might have a higher average value. Its more likely to be a sawtooth type wave rather than sine but its still just a wave at the level its being played.

 

Take those big grindy guitar solo's or distrted 303 sounds in dance music. They're heavy on the distortion, many created using desk distortion in the first place (overdrive the channel gain but reduce the fader to ensure it's still under 0db at the master or group output). Once they're recorded and mastered they're under or at 0db and your amp can't tell the difference. It's just a wave.

[Dukesy 0]

Input appreciated norty, but in basic terms, when it comes to telling the difference between a curved sound wave and a square sound wave, I'll personally venture on the side of caution than leaving it up to the amp to decide if it can tell the difference and if it's safe!

Likewise, neither can speaker drivers.

 

Whithout going into the ins and outs.......overall, the individual user has the ability to make a decision.

 

Can that user tell the difference between clipping and non-clipping?

Is that user prepared to take a risk?

Can the user afford to replace equipment?

 

http://www.dj-forum.co.uk/html//emoticons/smile.gif

[jackcu 0]

Thanks for all the feedback guys :)

 

I think I'll back off the main mixer output and increase the amp a bit, then have a good listen to hear if there is a major difference in sound quality / volume.

 

Cheers,

 

Jack.

[otronics 0]

Yep, It'll vary from set-up to set-up, but here's mine:

 

On the mixer (Soundcraft ES)

 

I always prefade CD's etc and adjust the gain so the LED's peak at 0 dB. I then have headroom if needed.

 

Main fader outputs are up to max - makes sense - 0 dB as well

 

Amp is usually at around 65%

 

Few dB +/- thanks to the graphic EQ.

 

I do not use a compressor/gate/limiter etc so nothing is changed there but I will eventually get a Behringer.

 

Amp is Warrior IS-1000, graphic is a Fisher.

 

[ToXiC 0]

I run my amps at full and put the channel sliders to full also.Have channel gains at around half 12 o clock setting.And master volume I turn up to about 3/4 [3 o clock setting] but if the clip leds light up I back down the master volume and the channel gain a bit.

 

Only had my amps clip once and that was some drunken idiot who grabbed my mic and yelled right down it at the top of his voice. http://www.dj-forum.co.uk/html//emoticons/sad.gif

Luckerly nothing broken as the built in clip limiter on the QSC amps works well!!! http://www.dj-forum.co.uk/html//emoticons/biggrin.gif