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[eric lenasbunt]

I'm changing our sub amp configuration to 2 itech9000hd, each running 3 EAW SB750 subs. So each channel will run 3 woofers at 2.7ohms. I need help finding the limiter magic number to keep these from blowing up. Anyone point me in the right direction?

[Ivan Beaver]

I'm changing our sub amp configuration to 2 itech9000hd, each running 3 EAW SB750 subs. So each channel will run 3 woofers at 2.7ohms. I need help finding the limiter magic number to keep these from blowing up. Anyone point me in the right direction?

There is no magic number.  There are a lot of "it depends".

Asking for a single number is like me asking you how fast you drive.

Unless you drive a single speed ALL THE TIME, the answer will depend on the type of road and the conditions of the road.

One set of numbers will ensure you don't blow them up, but you will ALSO not be able to get maximum performance out of them.  And vice versa.

[Brian Jojade]

Exactly what Ivan said.

The 2 extremes for limiter settings are setting where they are impossible to blow up, and the setting so that you can get the maximum possible output out of the speakers.

Setting for ultimate protection against an idiot operator (or DJ) would mean setting the limiter to 1/2 RMS power. - A full square wave is double the power of RMS power, so that's you're absolute protection point. Yeah, it's hard to achieve full square wave, but some DJs really try hard.

Now, with a normal operator, you can lift the limiters to allow full RMS power. If you don't drive dead balls into distortion you'll be fine.  For EDM music that has long sustained notes, this is very good practice, as you will be running at full RMS for enough time that more can cause damage.

For live or very dynamic music, you can get a lot more out of the system for those short bits without risk of damage, if your operator is cautious.  Peak power is often listed as 4X RMS power.  Speakers can handle that peak for very short periods, such as the kick of a drum, as long as the overall average remains below RMS power.

So, with those scenarios, you have to decide which point you want to set the limiter at.  In any case, if at any point during the show, you actually HIT the limiter on the amp, you simply didn't bring enough rig for the gig.  Limiters are there for protection against mistakes.  Kind of like having the air bag in your car. It's there to save you, but you don't want it going off at every stop sign.

[eric lenasbunt]

There is no magic number.  There are a lot of "it depends".

Asking for a single number is like me asking you how fast you drive.

Unless you drive a single speed ALL THE TIME, the answer will depend on the type of road and the conditions of the road.

One set of numbers will ensure you don't blow them up, but you will ALSO not be able to get maximum performance out of them.  And vice versa.

Completely fair Ivan. So where should I start? I typically set it and play with it until it is clamping down just before clip. Then back it off of it's sitting in limit all the time under normal use.

What's a better way to do it?

[eric lenasbunt]

Exactly what Ivan said.

The 2 extremes for limiter settings are setting where they are impossible to blow up, and the setting so that you can get the maximum possible output out of the speakers.

Setting for ultimate protection against an idiot operator (or DJ) would mean setting the limiter to 1/2 RMS power. - A full square wave is double the power of RMS power, so that's you're absolute protection point. Yeah, it's hard to achieve full square wave, but some DJs really try hard.

Now, with a normal operator, you can lift the limiters to allow full RMS power. If you don't drive dead balls into distortion you'll be fine.  For EDM music that has long sustained notes, this is very good practice, as you will be running at full RMS for enough time that more can cause damage.

For live or very dynamic music, you can get a lot more out of the system for those short bits without risk of damage, if your operator is cautious.  Peak power is often listed as 4X RMS power.  Speakers can handle that peak for very short periods, such as the kick of a drum, as long as the overall average remains below RMS power.

So, with those scenarios, you have to decide which point you want to set the limiter at.  In any case, if at any point during the show, you actually HIT the limiter on the amp, you simply didn't bring enough rig for the gig.  Limiters are there for protection against mistakes.  Kind of like having the air bag in your car. It's there to save you, but you don't want it going off at every stop sign.

Thanks Brian, that's helpful. I usually set them so they only come on and egregious levels. So far that has worked for us but now that I'm adding some more power I'm a little afraid I might let some smoke out.

[Ivan Beaver]

Completely fair Ivan. So where should I start? I typically set it and play with it until it is clamping down just before clip. Then back it off of it's sitting in limit all the time under normal use.

What's a better way to do it?

YES- calculate and measure wins EVERYDAY over guessing

I don't know what sort of adjustments you have on the amp, but I would start with a continuous limiter set for the continuous rating of the cabinets

Since the cabinets are 1700W @ 4 ohms, that would be 82V.

I would run the thermal around 1/3rd power (I used to say 1/2  power but have changed my mind on this with certain music style) with a attack around 3 seconds.

This would be around 50 volts

That should be a good starting point.

But if you want to be able to "bury the limiters" I suggest going to 1/4 power.

[David Sturzenbecher]

http://adn.harmanpro.com/site_elements/resources/856_1425410621/ITech_HD_LevelMax_Limiter_Readme_File_original.pdf


Sent from my iPhone using Tapatalk

[Mark Wilkinson]

http://adn.harmanpro.com/site_elements/resources/856_1425410621/ITech_HD_LevelMax_Limiter_Readme_File_original.pdf


Sent from my iPhone using Tapatalk

Separate RMS, peak, and thermal...very nice

[Ivan Beaver]

Separate RMS, peak, and thermal...very nice

So if he sticks with my earlier recommendation and then sets the peak for double the continuous (not program) he should be fine

[Luke Geis]

Without going into the super technical watt into volts equations and duty times, there is an easy way to do the job.

It starts with knowing how well you are powering the subs to begin with. In a perfect world you could in theory power the subs at their continuous rating for nearly ever. For EDM it is ideal to power the subs at their continuous rating. Under normal conditions you should never have a problem if that is the case. If you design the system to surpass the needs, then it is really hard to hurt things.

I for one do not like limiters setup for protection per se, as I feel a well designed system should have enough headroom that going into limiting won't be an issue. In your case three subs will handle 4,800 watts of continuous power. Your amp at a 2.7 ohm load will produce 4,200 watts. So the amp is nearly perfect for the subs in terms of continuous power. Just don't clip the amp. The new software in the amp is pretty good and has some easy settings you can use, or you can go crazy if you'd like. In this case a simple -3db limiter would probably work just fine. This would introduce limiting when the signal is 3db away from clipping in the amp. When you see the little red lights blink, you are done and only turning down the signal will help. Because the  amps are about perfect in this configuration with these speakers, you will likely see red blinky lights before any damage to the speakers can occur. The speakers peak power rating is 6,400 watts each! You are currently not even meeting the speakers combined continuous rating when ran as you have described. For EDM what you are doing is PERFECT. You can run the amps up to clipping all day long and the speakers will be fine. If you set a basic -3db limiter you will never ever be able to produce enough wattage out of the amp to do any harm to the speakers. Just follow the rules, if you see blinky red lights, you need to make them not blink.

As an aside, many amps these days have the clip lights blink when audible distortion is occurring. Many times this is 3db before actual clipping occurs. So when the lights flicker, you still have 3db to go. It is when the lights is solid red that you know you have met the end of the road.

According to my rough calculations you should be able to produce around 147db+ at 1 meter if you have all 12 subs running with the amps little red blinky lights going. This is the likely real world SPL you could achieve, so calculate for distance loss and you will have a good idea of what you are looking at. If think you will be heard and I don't think you will hurt the speakers.

[ProSoundWeb Community]