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[Eugen Jeličić]

Well yes but i meant, if they were sold as a kit that means the amp definitly won't overpower the box while it's under the clipping point. They probably wouldn't sell a 1.5kw amp wih an 800w rms box. Not saying it's not a good idea having a overly powerfull amp but with kits like these i doubt that would happen.

I understand but for some reason the yamaha boxes and my EV T18 boxes sound less powerfull and less controlled with the yamaha amps then my old peecker sound amps. You can here this significantly as the frequency goes lower. I remember with my boxes, it was like when there is a hard low bassdrop the amp looses control over the cone, and you can hear significant distortion. With my amps i could hear loads more of controlled power in the bottom end.

[Ivan Beaver]

Well yes but i meant, if they were sold as a kit that means the amp definitly won't overpower the box while it's under the clipping point. They probably wouldn't sell a 1.5kw amp wih an 800w rms box. Not saying it's not a good idea having a overly powerfull amp but with kits like these i doubt that would happen.

I understand but for some reason the yamaha boxes and my EV T18 boxes sound less powerfull and less controlled with the yamaha amps then my old peecker sound amps. You can here this significantly as the frequency goes lower. I remember with my boxes, it was like when there is a hard low bassdrop the amp looses control over the cone, and you can hear significant distortion. With my amps i could hear loads more of controlled power in the bottom end.

Sorry, but I totally disagree.

If you want to power a 800 watt continuous cabinet "properly" you should use a 3600 watt amp.

That would allow for the peaks to come through fine.

Now IN REALITY, especially in a dance club that is a STUPID idea.

A "standard" powering for a loudspeaker is around 1.5 to 2x the continuous rating for NORMAL material.  NOT heavy dance material that goes on for many hours.

Loudpseakers are rated for a specific waveform for a specific time.

Change either one and the ratings are no longer valid.

Different usages require different limiter setups.

In many/most cases a "dance" system should be limited to 1/2 or 1/4 long term power.

I know that sounds crazy-but is essential if the system is going to be pushed hard-if you want the speakers to last.

There is no "correct: size amp for a loudspeaker-only a correct size for a SPECIFIC application.

Different applications will be different.

Just because it was sold as a "package" only means that is what somebody thought would be a decent match up-NOT that they are designed for each other.

[Eugen Jeličić]

That's the logics i took when i tried briding my peecker sound amps to get 1800w into 8ohms for each 18" cabinet with rcf l18s800 inside. My t18's that i mentioned...

As i also mentioned, 3 of them are waiting for a recone kit since that night .

I ran the amps under 1/2 of that power which should still be around the RMS rating of those drivers.

Of course, there are 2 factors. First is, it was a dnb party. Basically it's close to pushing 3 sinewaves between 30 and 100hz through them with no stops and pushing them as hard as possible for 6 hours in a row with that material.

An there is the other factor. Only 3 drivers died. The ones that have been rewinded by hand of course. The reconed one is still working perfectly.

These yamaha boxes are rated 550w RMS, 1100w Program. These amps give them about 1000w before clipping. We have a limiter so the amps never clip but we quiet much run them as hard as possible sometimes for over 7 hours with no stops. They have been doing that for 6 years now. 2, sometimes 3 times a week.
They are still running perfectly. Only one box needed the drivers replaced 2 years ago but because of someones mistake, the amp clipped hard. That box with drivers much newer, is not working any better then the ones tortured for 6 years.

So i don't know what exactly do you mean when you say 1/2 of the rated long term power. If we are running a dnb party with constant sublines. I'm pushing subs as hard as possible but i never let them clip. What does that mean, how much power are they getting on average from the amp that will clip over 1000w at 4 ohms?

[Ivan Beaver]

So i don't know what exactly do you mean when you say 1/2 of the rated long term power. If we are running a dnb party with constant sublines. I'm pushing subs as hard as possible but i never let them clip. What does that mean, how much power are they getting on average from the amp that will clip over 1000w at 4 ohms?

This is a very complicated question.

The actual power depends on what the impedance of the speaker is at the freq that is being applied.

The impedance is NOT what it is rated at-no loudspeaker is.

It varies quite a bit and you may not be delivering the power you think you are-at the freq involved.

What I suggested was setting the limiter at 1/4 to 1/2 power, with a long attack time 3 seconds is a typical sub attack time at that power level.

But all limiters have an attack time.  They don't react immediately. So peaks can get through but it is the average level that does the damage.

It is not exactly easy to measure the actual voltage going to the speaker.

So it is a combination of freq-impedance-voltage and time that determines whether or not damage will occur.

It is good that you have not been having problems.  If you keep doing the same thing you should be fine.

And that is all that matters.

It is when you have problems tearing up drivers that it gets more complicated in trying to solve.

[Eugen Jeličić]

Of course. Since i'm not damaging the PA as time has shown i don't have much to worry about. But still, it's good to know.
The thing is i tend to push these yamahas as far as i can with long lasting sublines. Not peakes.
I used to get them near clipping levels with a subline that is really like a sinwave. That probably means running them around 700-800w average when the subline is going through.
They do survive however... 

And yes i understand drivers are reactive and change impedance depending on the frequency. That's why it's not reccomended running the amp at the lowest impedance it can work at. If it's running an 8ohm load and is capable of running a 4 ohm load then it still won't be tortured even if the driver is very reactive.

Also, would it be an idea that makes sense...
Using a compressor with a slow attack time to make the transients and peaks stand out more.

If there is a sub line at 50hz with short hits of 60hz sub on top of that and i want those short hits of 60hz sub to stand out more then i could insert a compressor that cacthes peaks but has an attack time of maybe 20-30ms. So the transient goes through.

If i don't like the fact that it's compressing everything just to get that 60hz hit out then i could insert it only on the sub matrix on the behringer x32 so it affects only subwoofer.
I use matrix sends on the x32 as a crossover.

[g'bye, Dick Rees]

I use matrix sends on the x32 as a crossover.

So what kind of slope does that give you?

[Eugen Jeličić]

So what kind of slope does that give you?

I can pick between 12 and 24db/octave. The matrix sends are designed to be used as a crossover if you want.
I use 24db/octave

[Ivan Beaver]

And yes i understand drivers are reactive and change impedance depending on the frequency. That's why it's not reccomended running the amp at the lowest impedance it can work at. If it's running an 8ohm load and is capable of running a 4 ohm load then it still won't be tortured even if the driver is very reactive.

Typically the impedance will mostly be HIGHER than the rated impedance.

Yes there may be a few freq that are lower-but if they are much lower then the cabinet should be rated at the next lowest standard freq.

Amps can drive lower impedances than they are rated for-but for how long it depends.

Remember that what we are talking about is not "exact", but has a lot of variables involved.

The main reason for not loading an amp down to its lowest rating is that the power supply will have more reserve for longer duration signals.

But many amps are designed to drive 2 ohm loads and can do it just fine.

You can look at the power ratings at the different impedances to see how well it can drive lower impedances

If the power goes up as the impedance goes down, then it is able to drive lower impedance loads just fine.

But if the power does not go up or only a little bit when you go from 4 to 2 ohms, then you are at the limit around 4 ohms.

It might can drive a 2 ohm load-just not very well or with much "authority".

[Eugen Jeličić]

Typically the impedance will mostly be HIGHER than the rated impedance.

Yes there may be a few freq that are lower-but if they are much lower then the cabinet should be rated at the next lowest standard freq.

Amps can drive lower impedances than they are rated for-but for how long it depends.

Remember that what we are talking about is not "exact", but has a lot of variables involved.

The main reason for not loading an amp down to its lowest rating is that the power supply will have more reserve for longer duration signals.

But many amps are designed to drive 2 ohm loads and can do it just fine.

You can look at the power ratings at the different impedances to see how well it can drive lower impedances

If the power goes up as the impedance goes down, then it is able to drive lower impedance loads just fine.

But if the power does not go up or only a little bit when you go from 4 to 2 ohms, then you are at the limit around 4 ohms.

It might can drive a 2 ohm load-just not very well or with much "authority".

I understand.
My peecker sound amps are rated 565w @ 8 ohms and 900w @ 4 omhs. And guys from peecker sound tech support told me that i should not use them at 2 ohms.

This factor of changing impedance of a driver, does it variate from a driver to a driver? Is it anywhere in the specs? And how is it related to frequency?
If i have an 18 sub rated at 8 ohms, what can i expect from it. Impedance jumps at higher or lower frequencies?

Are these variations significant enough to really make the amp give less power to the driver because overall it's impedance end's up over the rated impedance?

How does this factor make the amp have a hard time pushing the driver? It's sayed that these variations can start torturing the amp.

[g'bye, Dick Rees]

This factor of changing impedance of a driver, does it variate from a driver to a driver? Is it anywhere in the specs? And how is it related to frequency?

Well, Danley publish a graph of impedance:frequency.  I suspect few others do although they might furnish info upon request.  Here's a link:

http://www.danleysoundlabs.com/danley/wp-content/uploads/2012/04/TH-118-spec-sheet.jpg

[ProSoundWeb Community]