Yet Again - Limiter Settings

[yigba]

I have an old Driverack PA, a Behringer MDX2600 and a dbx266.

I want to protect Omni-Tops with Delta Pro12's and T39's with 3012LF's.

Powering the subs is a Crown XS1200 (1150 watts into 4 ohms).

Powering the O-Tops is a Crown Drivecore XLS1500 (525 watts into 4 ohms)

My mixing board is a Yamaha MG 16/4.

I've been following the various threads here on how to set the limiters but I cannot get the voltage to the proper limit in either of these amps without turning the amp sensitivity knobs down. I have to turn the XS1200 down to about 50% and the XLS to about 75% in order to get he 50 volts and 35 volt recommendations per the plans.

I am using a sine wave at 80Hz for the subs and 1000Hz for the O-Tops, and setting the channel fader to unity, bringing the signal into the board at just under clipping on the gain trim and then outputting the signal to the DriverackPA at just under clipping. So, the board is not clipping and the DriverackPA is not clipping.

What I am trying to do - and maybe this is where I am wrong - is to get the limiter to kick in when the signal going from the mixing board is just under clipping - and on this board it is at roughly unity on the main fader with this setup. That way no matter how much the board is turned up the voltage will never go higher than it's supposed to.

But when I do this with the amps input gains wide open I have to set the limiter's threshold so low that it is limiting the signal even when my mixer's main out master fader is near the bottom. And this is on both amps. I've tried the DriverackPA limiter, and the Behringer limiter at various settings. And yes I used them individually with the other one being taken out of the signal. On the Behringer I set the threshold to it's highest setting and it is still limiting the signal unless I am under -30 on the master fader. The same thing is happening with the Peak Limiter on the Behringer. Again, this is all with the amps wide open.

So far, the only way to get this to work with the mixing board without the limiter kicking in and having enough master fader movement - I can get up to -5 on the board now - is by setting the limiter with the amp gain knobs turned down as stated above - 50% on the sub amp and 75% on the O-Top amp.

So, is the signal from my board too hot and is screwing all of this up? It can go +24 dBu at it's max before clipping. I never get it that high because it would then clip the input of the DriverackPA, which only allows a +20 dBu input signal.

Lastly - should the limiter

Am I completely off base with this method? I sat there for 3 hours last night trying to go through different settings and turning down the amps was the best that I came up with. Is that ok or am I missing something? And I do the sound from the stage, so no one ever touches my stuff.

Lastly - on the Behringer limiter I have the ratio at infinity:1, the attack and release at it's fastest and the threshold at it's highest - then I adjust the threshold if needed. Then I also engage the peak limiter. All I want to do is allow the signal to come through at it's highest level without exceeding the voltage for the speakers. Should I make the ratio lower and just use the peak limiter to do this?

Sorry for rambling but this is driving me a bit nuts.

[Bruce Weldy]

Ok.....as I have the Yamaha board, the Crown amps, and the Driverack - I'll chime in.

I can't tell from your post - are you trying to run all of those devices at once? The driverack, the behringer, and the dbx? I'll assume not.

On the board, don't worry about channel gain - all that matters it the main output. Run the signal up until you hit the first yellow light. That's where you'll set the limiter so that anything above that stays at the same level.

The power amp should be all the way up. Your voltmeter should be attached to the speaker outputs of the amp with no speakers attached.

On the driverack.....first off - make sure you are in the limiter mode and not compressor. With the signal running, you should be getting a lot of volts from the amp. Start adjusting the gain on the limiter until the voltage comes down just below your desired voltage. Now, push the fader on the board all the way up into the red. The volt meter should still be reading the same. If not, you are doing something wrong.

I have done this with your exact same setup....MG board, Crown amps, and the old driverack PA. Above is exactly how I did it - and have done it several times as I've changed gear and amps. It's always worked just fine.

[yigba]

I was using the limiters - Driverack, Behringer - on their own, not altogether. And yes I was using the correct Limiter setting in the Driverack. I also tried various settings on that Behringer unit.

I was bringing the output of the Yammy board to the third yellow bar - just under clipping. This was unity on the main fader.

Why wouldn't I set the limiter to where the board maxes out just prior to clipping? Isn't this the highest point that the board can go? Or do I have it all confused?

My understanding was to set the gain structure properly first. Gain trim under clipping, individual channel at unity, master fader at unity. This basically maxes out the board just before clipping.

If I decrease the output to the first yellow bar on the board then my master fader will probably be at around -10. I want it at unity - but am I wrong in that expectation?

Thanks for the feedback - being that you had this equipment I'll try it and see how it goes. Did you use the Driverack's limiter in your system or did you have an outboard limiter?

[SirNickity]

For setting limiters, don't worry about the signal clipping from the source or mixer. I just turn everything up until increasing the gain has negligible further effect. If you want to calibrate it, you can find the just-at-clipping level and make sure your limiter engages at that point by adjusting the input gain on the Drive Rack, but it's not terribly critical. Different source material may slightly affect how the mixer inputs or master clips anyhow. Absolute output signal voltage is the only thing that matters, and the DR will ensure that, once it's set.

[Ryan A]

For setting limiters, don't worry about the signal clipping from the source or mixer. I just turn everything up until increasing the gain has negligible further effect.

Except for the fact that your mix will sound like crap due to distortion from having everything maxed out.

[Bruce Weldy]

I was using the limiters - Driverack, Behringer - on their own, not altogether. And yes I was using the correct Limiter setting in the Driverack. I also tried various settings on that Behringer unit.

I was bringing the output of the Yammy board to the third yellow bar - just under clipping. This was unity on the main fader.

Why wouldn't I set the limiter to where the board maxes out just prior to clipping? Isn't this the highest point that the board can go? Or do I have it all confused?

My understanding was to set the gain structure properly first. Gain trim under clipping, individual channel at unity, master fader at unity. This basically maxes out the board just before clipping.

If I decrease the output to the first yellow bar on the board then my master fader will probably be at around -10. I want it at unity - but am I wrong in that expectation?

Thanks for the feedback - being that you had this equipment I'll try it and see how it goes. Did you use the Driverack's limiter in your system or did you have an outboard limiter?

I use the driverack for limiting.

You are making this harder than it is. The input channel means nothing. In fact, don't even use an input channel - use the tape in. The only thing that matters is the master output. Gain structure is all about signal to noise - this is about output. Whether it's distorted or noisy doesn't change the amount of voltage that we send to the speakers.

Whether you use the first yellow bar or the third one doesn't matter....as long as it sends enough signal to get the amp to the voltage you need. It's just a reference point for you. I don't remember if the first yellow is at 0 or below....just pick the bar that is unity or 0. That way you know by sight when you are going to start hitting the limiter.

[SirNickity]

For setting limiters, don't worry about the signal clipping from the source or mixer. I just turn everything up until increasing the gain has negligible further effect.

Except for the fact that your mix will sound like crap due to distortion from having everything maxed out.

Oh for the love of..

I'm not implying he RUN it that way. Just that while you're setting the limiters, feel free to crank it to 11. Get your max level in, set the max level out, save the preset, and use the system with a modicum of common sense.

[yigba]

Just tried it again. It still doesn't let me put my master fader to zero, the amps wide open and not limit the heck out of the system even when I'm at -20 on the Master Fader. I want the limiter to kick in at only the top voltage for the speakers (and at unity on the board), not at let's say 20 volts. And that's what was happening.

So, simple work around that I figured out. In the DriverackPA you can reduce the output on each of the High and Low Crossovers. I reduced each by 8 db and voila - now the limiter kicks in with my master fader at unity, my meters on the board at the roughly the first yellow bar and amp gain knobs wide open. And it limits at roughly 50 for the lows and 35 for the highs.

Problem seemingly solved.

[Bruce Weldy]

I reduced each by 8 db and voila - now the limiter kicks in with my master fader at unity, my meters on the board at the roughly the first yellow bar and amp gain knobs wide open. And it limits at roughly 50 for the lows and 35 for the highs.

Problem seemingly solved.

Where were they set? Were they set at +8 or more? I use that to just balance out the tops and subs....the tops are always at -0- ..... the subs may get a little boost outside or a cut inside. They must have been through the roof.

[yigba]

They were both at 0 db. I'm just gonna attenuate the amp gain knobs down if I need to balance out the system. I figure the tops will need to be dialed down but I may be wrong.

I don't like any limiting happening before it should. To me it should only happen at 0 db on the master fader which (per your advice) I want to equate to one yellow bar on the mixer output meter. If I tried that without dialing back the crossover with the amp gains wide open the voltage was way over the 50 and 35 mark respectively.

I have the limiter on the driverack set on overeasy off with a threshold at around 4. If I didn't dial back the crossover output gain to -8 db the limiter would kick in at around -20 on the board. To me that is unacceptable. I want to get he most volume prior to the limiter kicking in, and want to use the unity setting on the fader as well as the unity setting on the board meter as a heads up that that's as far as the system will go. I am onstage as the lead singer and the only guitarist so I don't want to screw around with stuff mid show. A quick glance needs to tell me what is happening.

FYI - I usually never run the system near it's limit and just want this as insurance. But damnation, the limiter kicking in too early was getting me crazy as I also don't want to short change my system's volume capabilities.

[Bruce Weldy]

Something just ain't right here...

I run my 2-T39s off a bridged Crown at 1400 watts. I run my 4-OT12s off an XLS2500.....and everything works as it should.

Let's start back at the beginning....how many subs and which ones are you running? Are you bridging? If not, how many boxes per channel?

What you are describing sounds like there is way too much power for the voltage limit.

If you have that amp bridged, it will put out 3000 watts at 4 ohms. That right there would explain what's going on. May be worth your time to go back through the amp setup and make sure that you are taking the voltage reading off the correct speaker terminals and it's set up right.

Checking the manual, there is a bridge light on the front panel - it should be off. (but it could be burned out - that amp has some age on it). On the back panel, there is a normal/bridge switch located above and between the speakon connections. It should be in the up position. Then the voltmeter should be attached to the black and red terminals of channel number one.

I hope that the amp has been in bridge mode......because if it isn't - I'm about out of options.

Good luck...

[Bruce Weldy]

Well....there is one other option.

Move your test over to the XLS. Attach the sub output to it and put it in bridge mode - then see if it runs like it should. I run that exact amp in bridged mode and the limiter setup works fine with it wide open.

But, I'd check the other amp's setup out first.

[yigba]

I'm using 2 24" wide T39's with 3012LF's. I will use one on each channel of the XS1200. That amp puts out 650 watts per side into 8 ohms. And it is not bridged, it is in stereo.

Maybe I'm not explaining what is happening properly.

If I put the amp gains wide open and put the master fader to unity on the board (with one yellow bar on the output level) I can set the DriverackPA's limiter to the correct volltage. But then as I decrease the fader on the board the voltage also decreases but the limiter stays on. For example I saw on the multimeter that at -20 on the board the voltage was at roughly 18 and the limiter on the DriverackPA was still engaged. I could tell this from the amber lights on the Driverack.

I only want the limiter engaged when the voltage is at it's highest - roughly 50 volts, no?

So, I figured if the board was running too hot the answer must be to decrease the signal elsewhere. And the only place to do that without anyone being able to touch anything while ensuring that the amp gains are wide open is in the DriverackPA itself. Thus, the decrease in the crossover levels to -8 db.

I appreciate you taking the time to try and figure this out.

[byacey]

If you raise the input level until the Driverack starts to limit, and then drop the input level back by 18 db, the limiter should have released, even 1 or 2 db drop should release it. If this isn't happening, I would suggest there is a problem with your Driverack. The Behringer processor does the same thing?

Maybe you're driving the mixing board output hard into clip? Most mixers have at least 12 db of headroom over 0

Check the crossover output levels and the EQ in the driverack settings. Maybe you're adding a whole bunch of gain there.

[byacey]

I use a Driverack PA as well. I had a look at it today. With a 1Khz sine fed into one of my mixer strips, I brought the masters up until the master output meters read 0 dB. My mid high amp is run with the level controls wide open. I want my mid high boxes limited at 40 volts RMS, so I meter the output of the amplifier and adjust the High Xover level to obtain 40 volts. The limiter should be off while doing this. Ensure the meter you use is capable of true RMS measurement. I was using a HP 403B meter for the measuring, but my Fluke 87 III reads just as well.

Then when you turn the limiter on, simply adjust the threshold until the limit LEDs start to light, and you can see the voltage on the meter begin to drop as you lower the threshold. I set mine to hard limit at 39 volts.

I noticed pushing the master output up past "0" actually brings the output voltage lower than 39 volts as the limiter clamps down on the output.

Follow the same procedure for the low frequency output, but use 60Hz or so for the sine wave signal.