Amplifier speaker matching

[Andyb75]

Hi all

I played a gig last weekend in a marque all went well but I noticed my amp clip LEDs started to dim on and off when songs with high LF my speakers are EV115 passive 400w at 8 ohms and the amp is 1300w giving 650w at 4ohms and presumably 325w at 8 ohms my mixer was also going into the red at times

On thinking of adding a pair of Subs to help with the lower frequency s would this stop the clipping

Does the amp and speaker matching look correct ?

[Panchromatic]

The first thing you need to do is get rid of the red lights on your mixer - red lights are bad. If your channel on your mixer is running solid red the input is being clipped at this stage and the clipped signal being fed to the output side of the mixer, it doesnt matter if the output stage faders are down and not showing red lights the damage is done on the input side. The signal being fed into your amplifier would resemble a square wave and amps (and incidently Speakers) have problems processing square waves.

 

If you were to have the input signal set at 0dB, the main mixer output set at 0dB, the theory is the amlplifier would automatically be getting a clean siignal allowing more clarity and volume at a lower mixer level bearing in mind an amplifier should be run at full volume and the overall sould level controlled from the mixer.

 

If you want more volume after this then this would be the time to add more amps and speakers instead of overdriving your system.

 

If you add more amps and speakers but still clip the signal at the mixer end then the amps will still clip.

 

Remember an amplifier will amplify (or try to amplify) anything that is fed into it.

[paulears]

You were playing too loud. Keep in mind that doubling your output power is only just noticeable to your ears. The only real issue is that red lights mean distortion, and an overdriven amp and loudspeaker will be trying to handle content with more flat topped waveforms, that work the speakers even harder. The coils start to warm up, and if you persist, they will die. Red light means danger (as the old song goes) is a warning to be heeded. If you add a pair of subs, then the available power is going to be split further, meaning the volume will go down, so if you are playing venues where you need more volume - an increase in power is the next step - or maybe just swap the speakers for something more efficient.The EV's aren't the most efficient design around, and I think the bass end is often a bit flappy. I tried to check the crossover frequency to see if this shed any light, but the website says crossover frequency = 17000Hz, so I hope a typo! I had a pair of the previous model, and while there was bass - it was just a bit feeble and undefined, sort of a 'duh' rather than 'dah' if you know what I mean.

[Shez]

The general rule of thumb is that the amp should put about between 1.5 - 2 times the power handling of the speaker in order to give you sufficient headroom to avoid clipping. If your speakers are 400W 8 ohm, you should drive them with an amp capable of putting out between 600-800W in to 8 ohms.

If you're playing back highly compressed music (i.e. anything modern) then you can get away with slightly less power but I would still use an amp with a higher power rating than the speaker.

Above all, if the red lights are blinking, turn it down. Clipping the amp will eventually fry your HF drivers.

[Andyb75]

Hi guys thanks for replying

The amp gain was only set to half so that wouldn't help

It produces 325w at 8 ohms per side so the speakers are not being driven hard enough I think ill invest in another amp maybe the same that should give plenty of power hopefully especially If I decide to invest in a pair of subs

I agree the EVs are good but lack a bit of punch

[MarkPAman]

Hi guys thanks for replying

The amp gain was only set to half so that wouldn't help

 

With the amp sensitivity (it isn't really gain) at half, it can still output its maximum power, just that you have to put out twice as much from the desk. In this case, I think that's what you were doing. So by turning the amp up you can turn the desk down to achieve the same volume, which will help with that part of your problem.

 

However it doesn't help with the fact that the amp's really too small for your speakers. If it was clipping at the volume you wanted, it always will, regardless of the gain settings of equipment before it.

 

A second amp the same and run them both in bridged mode is one possibility, though twice the size & weight. I'd just get one bigger one which could probably be no bigger or heavier, then you've got one spare or to sell.

[Andyb75]

Mark

Thank you that makes perfect sense at what point would you know the speakers can't handle any more I guess it would be audible distortion at the lower frequency s ?