Running into the red (+db)

[UltraBeat Entertainment]

I've noticed lately i keep running into the red (+db) on my mixer which i didn't used to get with my old KAM mixer. Have been using my new mixer now for about 2 months and have noticed this at pretty much every gig.

To try to combat this i have put the amp almost on full power (which i don't like doing as it tends to drive the amp to hard).

Anyone have any idea's why this is happening? What damage can it do running into "the red"?
Does this just mean i need to upgrade my P.A system (again:() and buy a new amp and speakers?

[TonyB]

The level controls on an amp only control the level of the input signal. If you have to compensate by having higher levels on the mixer, the output of the amp will be the same as having lower levels on the mixer and higher levels on the amp.

So it won't make any difference to how hard the amp is working if you have the amps level controls at full.

If your mixer is flashing into the red, there is a chance that there is a bit of clipping/distortion being sent (I say a change because the level meters on the mixer aren't always accurate).

You should worry more if the clipping lights on the amp start to flash. That would mean that you need to upgrade to something a bit more powerful.

[Dimension Videotheque]

To be quite frank, these vU / dB meters are not accurate at all and should be used for indication purposes only. Mine often runs into the red but I am nowhere near overdriving the out put of the mixer. The only accurate way of referencing a meter is to use a 0dB input at 1KHz (Tone) and you should set the input gain upto 0dB whilst the meter is set to measure the master out put.

When pumping music into it, you will see that the beats will peak around +2/3dB which is fine. In terms of LED metering, it's pants and not a reliable measurement. By running your amp at a reasonable level, check to make sure the input to the amp doesn't sound distorted. Other than that, get a set of decent PPM meters that measure 'peak perfomance' - ignore the built in LED meters and use them as indicators only. They really are cosmetic, even on the more expensive range of mixers. Don't overdrive your amp and under drive the input, you'll just amply the noise on a low level input.

[UltraBeat Entertainment]

Thanks for all your input. I have learnt something already.

So if my amp is set at full its actually not working any harder than it would if it was set to 1/4 volume. And the controls on the front of the amp only controls the input volume.

Would i be correct in saying this?

So therefore would it not be better to always have the amp on full and control volume on the mixer?

[Dimension Videotheque]

Like Tony said, check the 'clip' lights on the amp rather than the mixer LEDs.


So therefore would it not be better to always have the amp on full and control volume on the mixer?

I'd be careful there, try to get your mixer LEDs referenced. I personally run my amp at about 3/4. I limit the input gains on the mixer so that if the master is turn on full on the mixer accidentally, it doesn't overload the out put to the amp.

Running your amp maxed out isn't a good idea. Always buy an amplifier matched to your speakers. Don't believe the hype in buying an amp that's much more powerful than your speakers in order to have a little more 'headroom'. It's like the old 'My amp goes up to 11' on the spinal tap film. :)

[UltraBeat Entertainment]

I can happily say that my amp is not clipping (that i have noticed and i check often) it was just seeing all those red LED's worried me abit as i didn't know what damage i was causing.

My amp and speakers were bought together to match so that shouldn't be a problem. Can't remember the spes's off my head but i think my speakers can handle slightly more than my amp can provide.

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Sorry relised i had posted it in the wrong place after i posted. knew it was only a matter of time before you lot sorted me out:). Thanks.

[TonyB]

I agree with Dimension Videotheque. The headroom is the amount of power the amp has in reserve to handle transient peaks. It is the difference between the amount of power the amp is using at the volume you are playing and the amount of power left before it starts to clip.

If you run an amp at just below clipping level, then you have no headroom.

[Richard Veal]

I was under the impression that you should have your amp set at max and use your mixer to control the voltage of the input.

[Dimension Videotheque]

I was under the impression that you should have your amp set at max and use your mixer to control the voltage of the input.

You can, but its not advised. It also brings noise floor up when you max out the amp and run your input low. The idea of the mixer output LEDs /Meter is to maintain a near enough constant input to the amp, an input level that is optimum for the amp to run comfortably at with out over driving or under driving the amp input.

[TonyB]

I was under the impression that you should have your amp set at max and use your mixer to control the voltage of the input.

Lots of people say the same. My usual reply is if it was designed to be run at the max all the time, it wouldn't have level controls :D

[Dimension Videotheque]

Lots of people say the same. My usual reply is if it was designed to be run at the max all the time, it wouldn't have level controls :D

So has my car engine (upto 6000 revs) but I don't do it. It's certainly less wear on the poor little transistors puffing away inside your amp if you don't have to run it flat our all the time. Heat causes alot of damage and wear.

[Richard Veal]

Surely it gives you more control.
Here's another thing you can take on board. This is what i do (just turns out that max is suitable)

Turn the amp to max.
push you mixer to max.
The amp will clip and potentially distort etc
Bring down the gain on amp until clip stops.
you should now have everything set correctly so that even at full tilt on mixer you will not enter the limits of the amp

[ppentertainments]

There are loads of diffferent advise about how to set up amps and mixer etc. I only wish we knew REALLY how to set them up.:bang:

[sleah]

There are loads of diffferent advise about how to set up amps and mixer etc. I only wish we knew REALLY how to set them up.:bang:

There is no single answer to that. Unless you buy a complete matched system that is designed as a single system.

For me disco I run the amps at max, unless I need to balance between two different amps. It works very well.
At work, I have a simple PA with 2 speakers, a slave amp and simple mic/line preamp. If I run the amp at max the gain is waaaaaaaaaaaaaaay too high which means the mixer's master is around 3, so I run the amps at about 6 so the mixer is about the same, which works fine.

So the only practical advice is really if it sound OK and you're comfortable with using the gear, i.e. how far you push the sliders, then don't worry.

Your system will soon let you know when it's not happy, it'll sound rubbish or drop dead or feel really awkward and uncomfortable to use.

[UltraBeat Entertainment]

Your system will soon let you know when it's not happy, it'll sound rubbish or drop dead or feel really awkward and uncomfortable to use.

Well that's useful in the middle of a gig:eek: :p :rolleyes:

Just in case it helps in anyway what so ever this is the mixer in question:
http://www.citronic.co.uk/product/product.php?s=172.774

Just out of curiosity what position do you all have your gain controls at? As i have gain controls for each channel i tend to keep mine at the half way mark.

[Richard Veal]

To use the car scenario if you think of the amp as the engine and the mixer as the throttle. My amps have the ability to run at full throttle so i have the gain to max.

But i am sensible with the throttle/mixer.

To look at the mixer i have 10 sets of green leds 2 amber and 3 red in respect to output signal strength. On an average night the mixer will show between 2-3 geen lights or to put it another way -8db.

IMO this ensures a clean signal but if needed the throttle is always there to fight through traffic.