Setting Limiters

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bgavin
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Re: Setting Limiters

#16 Post by bgavin »

This is the classic sound method used at the Roxy in L.A.
The PA quality really sucks for the opener, and gets slowly better until the headliner shows up.
The headliner gets loud clear sound, the openers get hind tit.

My daughter's band has opened at the Roxy for some big names, and this just plain sucks.
Especially when she can outsing the headliner any day, but can't be heard due to sand-bagged PA.
My biggest worry is that when I'm dead and gone, my wife will sell my toys for what I said I paid for them.

gdougherty
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Re: Setting Limiters

#17 Post by gdougherty »

Bill Fitzmaurice wrote:
David Carter wrote: when I turn down the amp, I can only get up to 11V before the limiter kicks in.
As it should be, since what the limiter limits its own output level, and therefore the input level to the amp. Not enough output? Turn up the amp.
BTW, there shouldn't be a S/N problem running with the amp wide open; if there is that indicates a gain structure problem elsewhere. Just because you have a high powered amp doesn't mean you have to run with its volume down low, because all amps run with roughly the same input sensitivity.
Poor gain setup, or more likely poor quality equipment. I'm ready to replace my DCX's with FX plugins in SAC. I get hiss and noise with nothing else in the signal chain besides the DCX. That's probably my problem.

gdougherty
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Re: Setting Limiters

#18 Post by gdougherty »

thijs666 wrote:http://billfitzmaurice.net/phpBB3/viewt ... x&start=18 :wink:

I can start a new topic on this (again, the old one is gone) or you can PM me :cowboy: .
Wouldn't hurt to put it in tips so it hangs around.

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thijs666
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Re: Setting Limiters

#19 Post by thijs666 »

Bill Fitzmaurice wrote:BTW, there shouldn't be a S/N problem running with the amp wide open; if there is that indicates a gain structure problem elsewhere.
That's also because your designs are so sensitive. I mean at 104 dB/W for the DR200 it would only take

1W @ 8 Ohms ~ 2,83 V
1/10th of power means 10dB less, so for 54dB a DR200 would need 1/100000 times less power -> 0.00001 W
0.00001 W @ 8 Ohms ~ 0.0089 V or


8.9 mV to produce 54dB, which is quite noticable in a silent environment. Even 44 dB (2.8 mV) is quite noticable.

Y'all keep in mind DR's can put out something in the neighbourhood of 128 dB, so that alone means 128-44 = 84dB dynamic range, with 44 dB assumed being the threshold of being able to hear noise (which it isn't in a REALLY quiet environment :!: ). Since the DCX2496 has +22 dBV output capability, the dynamic range jumps to 106 dB when your amp only needs 0dBV to be driven to it's max. The DCX has a dynamic range of 109 dB per the manual, so the needed 106 dB is almost at the max of the DCX :conf: .

I figured it would be better for me to deprive the DCX of it's +22 dBU capabilities for the sake of a lower noise threshold.

Ideally the noise threshold should be at 0 dB, meaning a dynamic range of 128 dB for the DR200's. With the power amp driven to it's max with 0 dBV and a headroom of 22 dBV of the DCX, the DCX should have a dynamic range of a staggering 150 dBV :shock: . Even 24 bits theoratically offers 'only' 144 dB dynamic range...
gdougherty wrote:
thijs666 wrote:http://billfitzmaurice.net/phpBB3/viewt ... x&start=18

I can start a new topic on this (again, the old one is gone) or you can PM me :cowboy: .
Wouldn't hurt to put it in tips so it hangs around.
I'll do that as soon as I find the time this weekend (maybe next).
BF cabs built to date:
2x T48 21" 3015LF; 1x T48 24" 2xBP102; 1x DR250 2510 loaded, cross firing; 4x DR200 Beta 8, melded array; 1x TT HL-10c; 2x WH Beta 8, melded 'array'; 3x AT 15" Tang Band W8-740P; 1x AT 15" JBL GTO1014

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lazyman
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Re: Setting Limiters

#20 Post by lazyman »

Something interesting about attack and release setting of the limiter from martin audio manual:
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JohnP.
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Re: Setting Limiters

#21 Post by JohnP. »

I don't own a DCX, so this is just a dumb newbie question...

Couldn't you set up a couple of different profiles in the limiter?
Say one limit for the amp being attenuated at 50% and another profile to limit the output of the DCX with the amp attenuated at 75% and another for the amp full on to "balance" your gain staging through the limiter and into the amp for best s/n ratio in each scenario?

Or would the best solution be to properly size the amps to max out at 50-75% of the rated power handling of the cabinets and run the amps full on and limit accordingly.

quaizywabbit
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Re: Setting Limiters

#22 Post by quaizywabbit »

i set my amp attenuators based on the clip indicators on the amp, using a test signal with the mixer setup for unity gain. Once I find that spot, i set the limiters with the attenuators in that spot.

CafSentryGnome
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Re: Setting Limiters

#23 Post by CafSentryGnome »

So how does that protect the speakers?

howarddoug1
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Re: Setting Limiters

#24 Post by howarddoug1 »

About 15 years ago a guy I knew that was a sound guy and built his own amps but didn't put any knobs on them for adjustment. I was just starting out as a DJ and getting al the information i could so I ask him why. He told me that they don't need a knob to adjust and if you have knobs turn to full open and forget about it. That if you use those knobs to turn down your speakers would work harder and make extra heat and might take out the copper windings, and that you have a mixer to control your volume and DB, it has all the knobs you need to turn and be careful with them.
He also told me to avoid Equalizer's because if you make to much of an adjustment at some DB that you will make the speaker work harder trying to get there and heat up those same copper windings. And that amps are the last thing to turn on and the first thing to turn off, so you don't pop a speaker starting up or shutting down.

Now I don't know if what he said is true or right, except for turning one last and off first, but I have followed what he told me.

I bought 12 speakers in 1996 and they are still working and not one replacement, every year I rotate the 18's top to bottom in their cabinets.

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BrentEvans
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Re: Setting Limiters

#25 Post by BrentEvans »

howarddoug1 wrote:About 15 years ago a guy I knew that was a sound guy and built his own amps but didn't put any knobs on them for adjustment. I was just starting out as a DJ and getting al the information i could so I ask him why. He told me that they don't need a knob to adjust and if you have knobs turn to full open and forget about it. That if you use those knobs to turn down your speakers would work harder and make extra heat and might take out the copper windings, and that you have a mixer to control your volume and DB, it has all the knobs you need to turn and be careful with them.
He also told me to avoid Equalizer's because if you make to much of an adjustment at some DB that you will make the speaker work harder trying to get there and heat up those same copper windings. And that amps are the last thing to turn on and the first thing to turn off, so you don't pop a speaker starting up or shutting down.

Now I don't know if what he said is true or right, except for turning one last and off first, but I have followed what he told me.

I bought 12 speakers in 1996 and they are still working and not one replacement, every year I rotate the 18's top to bottom in their cabinets.
Mostly myth based on incomplete knowledge. The volume controls on the front of your amp are input pads, they have nothing to do with output. Running wide open won't hurt anything per se, but isn't necessary and might introduce some noise in the system on some amps. They're there for level matching, mainly. EQs are necessary to equalize response, and will protect speakers from the high voltages generated in feedback loops which have a tendency to pop HF drivers.

Last on/first off is good practice.

As for reversing 18's yearly... build horns and you won't be lugging 18's any longer. :mrgreen:
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

quaizywabbit
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Re: Setting Limiters

#26 Post by quaizywabbit »

CafSentryGnome wrote:So how does that protect the speakers?
sorry, thats the starting procedure i use to keep the amp from ever clipping.

i mark where the attenuators are, and limit down from there........

osse
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Re: Setting Limiters

#27 Post by osse »

Bill Fitzmaurice wrote:
David Carter wrote: when I turn down the amp, I can only get up to 11V before the limiter kicks in.
As it should be, since what the limiter limits its own output level, and therefore the input level to the amp. Not enough output? Turn up the amp.
BTW, there shouldn't be a S/N problem running with the amp wide open; if there is that indicates a gain structure problem elsewhere. Just because you have a high powered amp doesn't mean you have to run with its volume down low, because all amps run with roughly the same input sensitivity.
How come the limiter kicks in that early when it's set for around -50v with the sine wave? The limiter in the DRPA acts the same, it's kicking in well before I set it with the sine wave when I play music throught it.

Is it becouse the voltmeter is not fast enought to catch the peaks?

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doncolga
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Re: Setting Limiters

#28 Post by doncolga »

Gregory East wrote:And he's saying he can't do it that way because his amps are too powerful for his limiter to reign in his overdriving mixer, so you'll just have to agree that blowing up speakers is bad.
I'm trying to clarify if I'm missing anything as that's what I ran into also. When I turned up my big amp all the way *and* set my mixer to meter halfway up to 0-4+, I was getting huge volts from the amp and the limiter really squashed the signal to bring the amp volts down to 48-50v. Turning the amp sensitivity down would not impact what's before it, so anytime the mixer was running 0-4+, the limiter was doing crazy gain reduction, which or course did not sound good. I chose to run off a smaller amp....320 per side into 8 ohms instead of 500.
Donny Collins
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osse
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Re: Setting Limiters

#29 Post by osse »

doncolga wrote:
Gregory East wrote:And he's saying he can't do it that way because his amps are too powerful for his limiter to reign in his overdriving mixer, so you'll just have to agree that blowing up speakers is bad.
I'm trying to clarify if I'm missing anything as that's what I ran into also. When I turned up my big amp all the way *and* set my mixer to meter halfway up to 0-4+, I was getting huge volts from the amp and the limiter really squashed the signal to bring the amp volts down to 48-50v. Turning the amp sensitivity down would not impact what's before it, so anytime the mixer was running 0-4+, the limiter was doing crazy gain reduction, which or course did not sound good. I chose to run off a smaller amp....320 per side into 8 ohms instead of 500.
320 watts? is it enought to drive the tubas with? The ipr1600 is 300 watts and it's dirt cheap nowdays... would be a good deal if it's a good match!

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doncolga
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Re: Setting Limiters

#30 Post by doncolga »

osse wrote:
doncolga wrote:
Gregory East wrote:And he's saying he can't do it that way because his amps are too powerful for his limiter to reign in his overdriving mixer, so you'll just have to agree that blowing up speakers is bad.
I'm trying to clarify if I'm missing anything as that's what I ran into also. When I turned up my big amp all the way *and* set my mixer to meter halfway up to 0-4+, I was getting huge volts from the amp and the limiter really squashed the signal to bring the amp volts down to 48-50v. Turning the amp sensitivity down would not impact what's before it, so anytime the mixer was running 0-4+, the limiter was doing crazy gain reduction, which or course did not sound good. I chose to run off a smaller amp....320 per side into 8 ohms instead of 500.
320 watts? is it enought to drive the tubas with? The ipr1600 is 300 watts and it's dirt cheap nowdays... would be a good deal if it's a good match!
I'm using a Behringer EPQ 1200 and that's into 8 ohms. http://www.behringer.com/EN/Products/EPQ1200.aspx

I'm running two Tubas off one side of the amp, so with a 4 ohm load its 600 watts and the amp runs dual mono. The amp has never clipped. One side can take the Tubas past 50 volts, so yes, it's enough. My limiter clamps at about 47 volts, but I'm careful to not push frequently over 40 volts. Once I have two more Tubas, I'll put them on the other side of the amp. :shock: I would have never guessed it either. Definitely a counter to all the marketing hype of gazzillion watt amps. If I add an amp in the future, I may go for something a little bigger, but not much. I like the idea of the amp not working too hard.
Donny Collins
Built:
Two 18" Tuba 30's 3012 LF
Two 26" Tuba 30's Lab 12
Two OmniTop 12's DL 2512 (Melded Array)
Presonus Studio One DAW
Harrison Consoles MixBus 32C DAW

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