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Keystone Sub Using 18, 15, & 12 Inch Speakers
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Old 26th September 2016, 07:24 PM   #1011
zettairyouiki is offline zettairyouiki  United States
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Originally Posted by Osse View Post
What is the difference between long term power limit and True power limiter? I don't have that sophisticated limiters in my drpa+.
As you probably know, Powersoft amps are NOT cheap. I wouldn't be surprised if they have enough smarts to measure the actual power being dissipated by the voice coil despite the complex impedance and hold a long-term average for the true power. I'm imagining long term power limit would then be a rolling average of voltage output with no concern for load impedance. Could be entirely wrong though, I haven't looked into it.

Limiting by peak voltage alone is a relatively ham-handed approach to driver protection because you're pretty much guaranteed to either sacrifice peak power headroom on transients or leave your drivers vulnerable to being cooked by low crest factor material.

I'm pretty envious of the ability to set 3 separate limiters in Powersoft amps. That definitely lets you have your cake and eat it too. Maximum performance with near-guaranteed protection.

Last edited by zettairyouiki; 26th September 2016 at 07:26 PM.
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Old 26th September 2016, 07:58 PM   #1012
Osse is offline Osse  Sweden
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I can see the need for two limiters(excursion and heat buildup), but not 3? I've never blown a driver on my own systems consisting both th and FLH's with a few thousand hours of running it in various configurations and under various circumstances with only peak voltage limiter engaged.
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Old 26th September 2016, 10:31 PM   #1013
radulescu is offline radulescu  Romania
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First, yes, Powersoft amps measures in real time the active power dissipated by the voice coil and cables. It can compensate for cable impedance and increase damping up to -2Ohms .
It has a voltage limitter brick wall type and an attack release voltage. There is a white paper with their true power setting and that setting measures the real power that is consumed by the driver and can adapt the output based on that, disregarding the effects of voice coil heating .
It makes graphs with power input power output, temperature, amps,volts,you name it. They are expensive, I can't afford them but I had my subs installed in a club for half a year on a K8 and also worked with K20, K10,X8 and X4. What I can tell you is that no other amps in this world is getting even close to be as well suited for pro audio market as them. Tried Linea research ( which are wonderful) Lab grupped, Crown Itech,Crest, a clone now,none of them comes close regarding usefulness.

Regarding those Xoc with that setting, I really like the kick I get with those settings and I can stay relaxed in the long run. If I forced it a bit to squeeze 2 dB more, I would probably get them but also I would get 10% more THD and less efficiency because of power compression . And probably no one would even care. I tried with no peak limitter but the driver flapped and on transients it gave a muddy bass.so this remained. Anyway, with those true power limiters, one can see in real time an 1,5seconds average power consumption from the driver on Armonia and even playing Outerdub - Sephiroth song or Wiz Khalifa-On my level and it never got higher than 800 Watts, so it probably never engaged in half a year.
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Old 26th September 2016, 10:46 PM   #1014
zettairyouiki is offline zettairyouiki  United States
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Originally Posted by Osse View Post
I can see the need for two limiters(excursion and heat buildup), but not 3? I've never blown a driver on my own systems consisting both th and FLH's with a few thousand hours of running it in various configurations and under various circumstances with only peak voltage limiter engaged.
I'd agree that 2 should be plenty for near all practical uses, but could it perhaps make sense at least in theory to have a more generous peak limiter with a very fast attack time for the upper bandwidth of the box and a more restrictive limiter with a fractionally slower attack time for the lower bandwidth where excursion is increased? Both of them would still be quick limiters to prevent excursion mechanical damage.
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Old 27th September 2016, 07:57 AM   #1015
USRFobiwan is offline USRFobiwan
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radulescu wrote exactly the words i wanted to point out:
Quote:
I keep the gain in the amp or processor as low as it is needed and I keep my eyes on the DJs and only when the go in Over on their mixers, the limiter engages on peaks.
Some seems to think that having a limiter is the same as 'allowing' to be as loud as possible because having a limiter. However, engaging the limiter, results in over compression of sound > squashed wave-forms > more work for driver > death driver.
Limiter is to save your driver as last resort. Continuously hammering the limiter and/or allowing DJ's to push their master into the red is asking for trouble. Personally I would tell the DJ that red lights are for prostitutes and if he needs to continue playing in the red zone I would be happy to arrange a pimp for him.
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Old 27th September 2016, 07:03 PM   #1016
zettairyouiki is offline zettairyouiki  United States
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Yeah, but that's somewhat missing the point. YOU are functioning as the limiter now. And while obviously having some knowledgeable person overseeing the equipment at all times and doing the job of a limiter manually is preferable, it's not practical.

Some people are interested in idiot-proofing the subs so they are protected from any kind of possible input signal, from 40hz sinewaves to pink noise to massively clipped program material. And while it's easy to set a peak limiter so low that the amp simply can't pass enough power to cook the driver, you've just eliminated tons of headroom.

Hence why having 2 (or more) different limiters is appealing for people who have equipment being used in potentially abusive environments without wanted to constantly supervise it.

Last edited by zettairyouiki; 27th September 2016 at 07:18 PM.
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Old 28th September 2016, 12:03 AM   #1017
Zero D is offline Zero D  United Kingdom
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Originally Posted by USRFobiwan

Personally I would tell the DJ that red lights are for prostitutes
Hilarious, i'll remember to use that one in future

Unfortunately, Most DJ's don't have a clue about sound or electronics etc etc. Some think they do, but if pressed they only show themselves up about how little they Actually know. Of course they don't like being shown up & embarrassed, especially in front of other people, but that's their fault for being ignorant !

I was doing an event several weeks ago, & was behind & off to the side of the DJ off & on throughout the night to on check things. Every now & then the red peak leds kept lighting up on the mixer channels. The first few times i waited to see what he did, which was nothing. The next time it happened i moved over & pointed to the flashing red led, & advised him to reduce the channel gain. And in future when doing pre fade monitoring on the headphones etc, to make sure the level stays under the red. As not not doing so makes me & him look bad, as it negatively affects the sound. He said, "yeah i know, i just forget " Not a professional attitude is it, & sadly very typical too ! You might think they would want everything to be as good as it could be, but most don't seem to care !

As an aside, nearly all the tunes he played were mp3 from a usb stick ! I asked him after the event had finished, if he ever played higher quality wav's or cd's ? He said " sometimes, but most of what he has is mp3" ..... This is also typical these days. More proof that most are clueless, and/or don't much care !

What's really interesting, is that when we do vinyl events with old school DJ's playing, for eg club classics from the late 70's & into the 80's, we get tons of compliments from the DJ's/customers/eventers about the sound quality. At events like the mp3 one, all we get is comments about how loud it was, meaning good to them !
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Old 28th September 2016, 12:44 AM   #1018
djk is offline djk
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Use a DBX with

Program-dependent attack and release times (set the release times to one minute)
Beyond-infinity compression ratios (gets quieter as they overdrive)
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Old 28th September 2016, 10:40 AM   #1019
weltersys is offline weltersys  United States
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Originally Posted by djk View Post
Use a DBX with

Program-dependent attack and release times (set the release times to one minute)
Beyond-infinity compression ratios (gets quieter as they overdrive)
djk,

Following your above "advice" leads to frustrated DJs cranking their desks until the clipping makes it seem louder, due to the ragged additional high frequency harmonic content. The additional HF content can in turn burn out HF drivers, unless they are protected by separate long-term limiter circuits, which is often not the case with top cabinets using passive crossovers.

I hear of this happening over and over, surprised individuals having to replace expensive diaphragms they thought were "protected" by compression.

Art
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Old 28th September 2016, 10:57 AM   #1020
USRFobiwan is offline USRFobiwan
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@Zero-D. Put in your contract that DJ's should provide at least 320kb mp3 format or preferable FLAC. No youtube downloaded mp3 content. Also put in that if Low quality sound source is used, you may/can shutdown,lower volume etc to protect your equipment.

Also let the stage-manager know you want to talk to DJ's before they going on stage or (if it is a good stage-manager) let the stage-manager point out the operation of the equipment.

IMHO you really want to help the DJ / act to let the crowd enjoy the best possible sound experience.
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