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Peak limiting for driver protection
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Augusts View Drop Down
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Points: 150 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Augusts Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 11:46am
Thank you

Im sorry, it seems people are getting cranky because of my post
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Points: 6949 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 12:44pm
"I am telling you guys, the speaker hit the back plate because, the Vpeak was 141Volts for a 4ohm driver. that is 6000w"

R = 4 ohm, nominal resistance!

In real life, your speaker becomes a complex impedance that will vary with frequency. Do you understand the difference?

Some manufacturers supply an impedance curve with their products, but put the driver in a box and that changes again. The only way to find out is to measure - or get one of those modern, fancy amps that tell you!  Smile

Like I've already said, do a sweep test with a signal generator and see  what going on.
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Augusts View Drop Down
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Points: 150 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Augusts Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 12:51pm
Yes, I know it is a nominal resistance. I know what are you saying, thank you, I have recalculated the resistance to a precise 4ohms for the convenience of using treshold calculators. I think the problem could have been that I had set a too long of an attack time for the limiter. Something must have gone through the limiter.

Edited by Augusts - 28 December 2022 at 12:54pm
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Points: 979 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 1:39pm
What kind of cabinet + driver are we talking about? With some drovers its impossible to hit the backplate due to the spider limiting travel.
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Points: 3012 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 2:09pm
excursion varies with frequency. What about applying dynamic eq or sidechain compression?
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Points: 6949 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2022 at 4:21pm
Originally posted by Augusts Augusts wrote:

Yes, I know it is a nominal resistance. I know what are you saying, thank you, I have recalculated the resistance to a precise 4ohms for the convenience of using treshold calculators. I think the problem could have been that I had set a too long of an attack time for the limiter. Something must have gone through the limiter.



Ok, you obviously (now) have it under control.  Good luck!  Smile
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Elliot Thompson View Drop Down
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Points: 5069 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2022 at 9:29am
Originally posted by toastyghost toastyghost wrote:

 


I give up. You don't seem to have built a speaker in a decade and are advocating using a basic broadband SPL meter, yet you're saying I'm the one lacking in experience developing modern loudspeaker DSP presets?

I'm not even going to waste my time trying to justify myself. If you truly think I'm just blindly copy & pasting stuff then you're either deluded or intentionally trolling at this point.

Or perhaps simply don’t read what others actually post before weighing in

Good luck with your limiting, Augusts.


Yes, Give up. You do not have any experience on the issue August is facing. It's that  simple! LOL

Best Regards, 
Elliot Thompson
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Points: 5069 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2022 at 9:42am
Originally posted by smitske96 smitske96 wrote:

What kind of cabinet + driver are we talking about? With some drovers its impossible to hit the backplate due to the spider limiting travel.

Some drivers that offer dual spiders can have one fail. The end result is one driver moving stronger than the other drivers within the chain. 

Best Regards, 
Elliot Thompson
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Points: 979 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2022 at 10:57am
If you have a spider fail on you due to excursion, you are well passed the limit of something bearable to listen to.

I use peak limiting more as the max before it is going to sound crap. 
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Points: 148 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Esc4pe Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2022 at 12:27pm
Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by toastyghost toastyghost wrote:

 


I give up. You don't seem to have built a speaker in a decade and are advocating using a basic broadband SPL meter, yet you're saying I'm the one lacking in experience developing modern loudspeaker DSP presets?

I'm not even going to waste my time trying to justify myself. If you truly think I'm just blindly copy & pasting stuff then you're either deluded or intentionally trolling at this point.

Or perhaps simply don’t read what others actually post before weighing in

Good luck with your limiting, Augusts.


Yes, Give up. You do not have any experience on the issue August is facing. It's that  simple! LOL

Best Regards, 



Toasty’s posts have been an absolute godsend for me (and I’m sure countless others) while learning throughout the years. This poor attempt of trolling should be considered blasphemy as far as I’m concerned LOL

I know who I would take advice from.

My simpleminded 2 cents that no one asked for: could you take more kit to the events and run with less power instead of ragging a smaller amount and surely won’t run into this problem then? I never damage drivers and rarely use any limiting at all? To bottom out a driver is quite a task, Elliot does raise a point that they may be becoming unloaded due to improper setup maybe? 


Edited by Esc4pe - 29 December 2022 at 12:49pm
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bob4 View Drop Down
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Points: 1766 		Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 30 December 2022 at 8:15am
Interesting topic, and first of all, happy to see that August has found a practical solution to his problem! 

Originally posted by Augusts Augusts wrote:

+3db for Peak power which is as I understand a very short peak that cannot do a mechanical damage to a subwoofer because it is very short.

However, I don't understand this repeated statement of yours.

You probably refer to the impulse peaks of the full range audio signal. Your woofers are acoustically capable of playing back frequencies up to 1- 2 kHz. 
 Yes, if you played a FULL RANGE signal through your woofers,  they would roll of somewhere around 1-2 kHz. That part of the signal also contains a lot less energy in relation to the bass, and would be insignificant.

So for INPUT limiting of full range signals, your statement is correct.

But all that  is completely irrelevant to the subject of bass signal lmiting! 


In your dsp, i suppose you are using a dedicated OUTPUT limiter on the subwoofer channels output that sees a filtered bass signal only. 

That limiter only sees sub frequencies, lets say 30-120 Hz. That signal still has peaks, obviously. There is no part of that filtered signal that will be "too fast" for the woofer to follow. So you HAVE to consider the peak part of your subwoofer signal.  The waveforms will probably be quite close to a sine wave, due to the narrow bandwidth the signal will contain only a fundamental and one or two overtones (e.g. 35, 70, 105 Hz). As toasty quoted, typically 6 dB crest factor. 

I suppose that the optimum solution would be to set your rms limiters so that your subs stay within xmax most of the time, and set the peak limiter to reign in the cone somewhere between xmax and xmech, before it hits the back plate. Prevention of power conpression could also be considered.

As others suggested, reviewing the low corner of your cabs and hpf setting would probably help as well.

Frankly, you have not provided enough information. What kind of cabs?  What was your test signal in your excursion tests? Music? Bass drums/impulses? Sine waves? 

In your inquiry, you have also omitted the time constants of the limiter(s).

Toasty's replies, as always, thorough and exhaustive Clap 
Happy to learn more Embarrassed



Edited by bob4 - 30 December 2022 at 8:19am
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Pasi View Drop Down
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Points: 2730 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Pasi Quote  Post ReplyReply Direct Link To This Post Posted: 31 December 2022 at 12:11pm
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Edited by Pasi - 31 December 2022 at 12:16pm
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