Amp & Speakers (exeeding power ratings)

[sonofalesbian]

I've just bought myself an amplifier (AH2400) rated 1200W a channel @ 4Ohms. My current set up is 2 Otops loaded with the delta 12 driver rated at 400W, and some homemade bassbins (soon to be replaced by T30's) rated 300W each. I plan on putting the tops on one side and the bass bins on the other side.
I don't currently own a limiter, what do i need to be wary of when doing this as each channel of the amp can put out more power than is needed for the speakers? If i turn up the volume knob half way, would this be putting half of the max power the channel can provide through the speakers?
Also i have read that you can use a multi meter to set a limit but cannot find the thread, could anyone direct me?

[sonofalesbian]

Also i have read that you can use a multi meter to set a limit but cannot find the thread, could anyone direct me?

found it. (for anybody else wanting it - http://billfitzmaurice.info/forum/viewt ... p?f=6&t=12)

[Bill Fitzmaurice]

If i turn up the volume knob half way, would this be putting half of the max power the channel can provide through the speakers?
?

No. The only way to protect your drivers is with a limiter.

[sonofalesbian]

ok, im aware my speakers will not be fully protected, but are there any precautions i can take to reduce the risk whilst i dont have a limiter?

george

[Bill Fitzmaurice]

ok, im aware my speakers will not be fully protected, but are there any precautions i can take to reduce the risk whilst i dont have a limiter?

george

With tops you'll hear distortion well below the danger point, but with folded horn subs you will not. Get a limiter, it will cost you less than blown drivers.

[sonofalesbian]

i get the hint, a limiter is on the top of the shopping list.

[Zack Brock]

You could take the precaution of not playing your speakers until you buy a limiter and set it properly

[Landl.livesound]

You could take the precaution of not playing your speakers until you buy a limiter and set it properly

Or not leaving them in your garage, cause then the rodents might get to them. So you might want to put them in your room and keep them lifted off the floor to keep them completely safe.



In all seriousness, a fast-acting peak limiter is not the right tool for the job in protecting speaker cabs in 99% of cases.


Take Care!
Phil

[Turntablist]

In all seriousness, a fast-acting peak limiter is not the right tool for the job in protecting speaker cabs in 99% of cases.

Because?

[Landl.livesound]

If i turn up the volume knob half way, would this be putting half of the max power the channel can provide through the speakers?
?

No. The only way to protect your drivers is with a limiter.

Hey Bill,


I would say that, that is not a complete statement as there are also several others (better) ways to protect drivers being:

(a) Being a smart operator and not turn up the rig past the point that it can take
(b) Knowing the limits of your system so you know the point of (a)
(c) Using robust designs/drivers
(d) Bring enough rig for the gig


99% of cases of failure are due to operator error, so I would say it might be more effective to put a limiter on the operator and not squash the dynamics out of the program material with a quick acting limiter.


To quote someone else recently in a limiter thread; "Turn the $hit down"

It will solve a lot of problems.


Take Care!
Phil

[Zack Brock]

I can appreciate advice that Instructs one to be cautious and smart. Only problem there with your advice Phil is in tradional speaker cabs you can hear distortion and turn it down. In horn subs you can't so you could easily blow drivers and not even realize until you see magic smoke and hear no more bass.

And why is a peak limiter not effective?

One thing to help out the original poster - the volume knobs on a power amp are input attenuators, not output adjuster. So even with the amp vol knob turned half way down the amp can be inadvertantly driven to its full output power with the right high input voltage from a mixer.

[Landl.livesound]

In all seriousness, a fast-acting peak limiter is not the right tool for the job in protecting speaker cabs in 99% of cases.

Because?

Your main enemy is the long term thermal heating power not the quick peaks that a peak limiter catches. What that kind of limiter will actually do is *raise* the average level and therefore get you closer to burning out the VC.

As Bill has said most of these drivers are robust enough to take peaks much higher than the continuous level it is rated for (As a driver should be). And from what I have gathered, Bill does not recommend amps capable of mechanically damaging most of the drivers he uses, as the amp will start to clip first. So the main enemy then becomes the heating power behind all this that will burn out the VC.


Another good quote that I had just read so it was fresh in my mind:

"You can't use technology to solve a people problem." and along with "Turn the $hit down."




Take Care!
Phil


P.S. That should solve a lot of problems unless you have some long term slow acting limiters, *then* you can do a much better job at protecting the VC's in the drivers.

[Landl.livesound]

I can appreciate advice that Instructs one to be cautious and smart. Only problem there with your advice Phil is in tradional speaker cabs you can hear distortion and turn it down. In horn subs you can't so you could easily blow drivers and not even realize until you see magic smoke and hear no more bass.

And why is a peak limiter not effective?

One thing to help out the original poster - the volume knobs on a power amp are input attenuators, not output adjuster. So even with the amp vol knob turned half way down the amp can be inadvertantly driven to its full output power with the right high input voltage from a mixer.

Hey Zack,

Pretty much the peak limiter is not the right too for the job because your main enemy is the heating power, like I mention to Turntablist above. A peak limiter will only raise the heating power when it starts to actually do something.


Here is a decent article going through some things:

http://campuspa.com/downloads/Loudspeak ... entals.pdf


Take Care!
Phil

[Zack Brock]

All it takes is a brief transient peak of a miisecond in length to cook a driver.

Properly set, peak limiters are effective in preventing this. And a properly set peak limiter is not going to squash your dynamics, whereas an RMS limiter would (essentially just an RMS compressor in that mode).

[Bill Fitzmaurice]

[

Here is a decent article going through some things:

http://campuspa.com/downloads/Loudspeak ... entals.pdf


Take Care!
Phil

Nothing in that article bears the slightest bearing on the reasons why limiting, as well as high-pass filtering, must be used with folded horn subwoofers. This does explain the reasons why, and that's why it's included in the plans and as a sticky here on the forum:
http://billfitzmaurice.info/forum/viewt ... ?f=1&t=698