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Author Topic: Users of dbx venu360 could use some help with the limiters  (Read 1159 times)

Jay Michael Tetz

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Users of dbx venu360 could use some help with the limiters
« on: August 06, 2019, 11:05:21 pm »

Greetings all.  After a decade of using self powered cabinets I have moved into running some passive subs and tops. I am admittedly on the learning curve with passive gear so looking for some guidance.  I am running Danley SH-46 tops with Josh Ricci designed Skram subwoofers using B&C 21SW152 4 ohm drivers.  I am running 2 subs per channel 2 ohm load off of a powersoft k10 amplifier. Music is predominately prerecorded electronic music, from bassy stuff to techno and trance.

 I am currently working on dialing in my limiters for my sub channels.  I have manually set my gain structure as recommended in the DBX literature. Considering the 2000 watt rms rating of the drivers I have calculated a max voltage of 89.44 volts. From my reading so far I have heard it said that I should measure voltage across the + - terminals of my amplifier with load disconnected and processing off while sending perhaps a 60hz sine wave signal through the amp.  I can then adjust the threshold of the limiter until I get less than 89 volts.   

Questions.

1.  I imagine I should set it even lower than 89 volts to ensure some safety wiggle room, any recommendations on a value?

2. As I am running a 2 ohm load with 2 drivers in parallel do I still use 89 volts as my max target? I think it should be the same, but not 100%!

3. Every article, resource I have read so far discusses quite a bit about how to set attack, release, hold etc but the venu360 has other settings like overeasy and overshoot that I am not finding much conclusive info on.

So far I have my attack set at 7ms.  I have read that good settings for attack can be between 4ms and 10ms.  It sound like one should use values closer to 4ms for amps that are working near their limits, or towards 10ms for amps with lots of headroom. 7ms seemed a happy medium? Thoughts?

I have seen it stated that using 2x or 4x the attack value for release should be followed, however the venu360 gives release settings in dB/s's.  The only info I have found on this seems to say faster is better, a suggestion of 100dB/s was given, so that's what I have it currently set at.

The venu360 has a setting for hold, this is a setting that is confusing me, not really sure what to use here? 

That leaves me with the Overshoot and Overeasy settings.   I am currently using an Overeasy value of 5 and and Overshoot value of 3.0db as it was mentioned in the gain structure set up instructions of the manual.

There is also the option to set the limiter in auto mode, which turns off the ability to set attack, hold, and release values.  I have not ever tried this setting.

I also have peak stop plus set to on.

If any users of the Venu360 could care to comment, or critique my settings or reasoning's I would greatly appreciate it.

Thank you 



Michael Thompson

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #1 on: August 07, 2019, 02:03:23 am »

1. Depends how safe you want to be...

2. Yes, still the same voltage, but twice the current.

3. Overeasy is just the compressors knee adjustment.  If you raise this setting it the "limiter" will threshold becomes lower, but the compression ratio gradually increases until your target amount, which in the case of this limiter would theoretically be infinity:1.  I'd probably leave is hard knee, but this is really to taste.

Overshoot is like another limiter in the chain and is set to a higher level.

In practice you would use the "limiter" to control RMS values.  Some peaks will get by because of the attack time.  That time depends how fast the voice coil heats up.  For a sub I'd say 30ms or so if it's your only limiter, but if you have a second limiter like the "overshoot" function you can go much longer on the attack of the RMS limiter.
 Then you set the second limiter (overshoot in this case) to avoid over excursion of your drivers.

I would adjust "hold" to 2x-4x your attack time and adjust release to taste.  You could leave hold at 0 and adjust the release time longer, but release time is defined differently for different manufactures.  In this case they take the more scientific approach and actually define a slope, but the slope would have to be pretty shallow to be effective if you don't use the hold time.  Like less than 10db/s I'd say.

I'm not sure about Auto mode, but in on most processors it will look at your crossover frequency and then determine time constants based on that.

Hope that helps some
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Mike Caldwell

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #2 on: August 07, 2019, 10:16:28 pm »

Here's a link to a Powersoft paper on limiters that's a good read with good info.

http://www.powersoft-audio.com/en/docman/804-how-to-setup-limiters?path=

Kevin Maxwell

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #3 on: August 08, 2019, 09:29:58 am »

Why are  you using the DBX360 to do the limiting and not the built in limiting in the K10?
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David Allred

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #4 on: August 08, 2019, 11:43:36 am »


The venu360 has a setting for hold, this is a setting that is confusing me, not really sure what to use here? 


I also have peak stop plus set to on.


Thank you

Hold - is to avoid "chatter" by assigning a time required to remain "clamped" before release can begin.  Hold set to 20ms... a single 5ms burst over setting... limiter will be latched for 25ms (5+20HT) and then begin the release.   Hold set for 20ms... a 5ms over burst...  followed by a 10ms reduction... followed by a 5ms over burst... limiter will be latched for 40ms (5+10+5+20HT) and then begin the release.

Peak Stop Plus (ON) = peak limiting
Peak Stop Plus (OFF) = RMS limiting
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Art Welter

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #5 on: August 08, 2019, 01:26:53 pm »

I am running Danley SH-46 tops with Josh Ricci designed Skram subwoofers using B&C 21SW152 4 ohm drivers.  I am running 2 subs per channel 2 ohm load off of a powersoft k10 amplifier. Music is predominately prerecorded electronic music, from bassy stuff to techno and trance.

Considering the 2000 watt rms rating of the drivers I have calculated a max voltage of 89.44 volts.   

Questions.

1.  I imagine I should set it even lower than 89 volts to ensure some safety wiggle room, any recommendations on a value?
2. As I am running a 2 ohm load with 2 drivers in parallel do I still use 89 volts as my max target? I think it should be the same, but not 100%!
3. Every article, resource I have read so far discusses quite a bit about how to set attack, release, hold etc but the venu360 has other settings like overeasy and overshoot that I am not finding much conclusive info on.
4. If any users of the Venu360 could care to comment, or critique my settings or reasoning's I would greatly appreciate it.

Thank you
Jay,

Josh Ricci, radulescu_paul_mircea and others have already provided great information prior to your questions here.
http://data-bass.ipbhost.com/topic/771-burnt-a-costly-drivers-coil-with-a-pricey-ampfollowup-and-prevention-of-costly-mistakes/

I'll take another swing-
1. The B&C 21SW152-4 can easily take 4000 watt peaks, around 126 volts.
2. If the amp delivers the voltage into the load, it does not matter whether there are 1 or 10 drivers.
3. When using a single limiter, the attack, release, hold etc. can be used to compromise between peak and RMS settings.
4. Playing predominately prerecorded electronic music, which often has bass with 3 dB(or even less) dynamic range, you seem to be missing the "elephant in the room"- average power. The average level for a driver like the B&C 21SW152-4 should probably be in the 400 watt range (10 dB less than it's peak rating!), only 40 volts or so to avoid cooking the voice coil.
Fortunately, between the Powersoft k10 and the Venu360 you have plenty of options available that won't require sacrificing peak potential for long term heat management.

Have fun on the 8/15/19 weekend, keep those driver's magnets below the boiling point of water ;^).

Art
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Ivan Beaver

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Re: Users of dbx venu360 could use some help with the limiters
« Reply #6 on: August 08, 2019, 03:37:18 pm »

Jay,

Josh Ricci, radulescu_paul_mircea and others have already provided great information prior to your questions here.
http://data-bass.ipbhost.com/topic/771-burnt-a-costly-drivers-coil-with-a-pricey-ampfollowup-and-prevention-of-costly-mistakes/

I'll take another swing-
1. The B&C 21SW152-4 can easily take 4000 watt peaks, around 126 volts.
2. If the amp delivers the voltage into the load, it does not matter whether there are 1 or 10 drivers.
3. When using a single limiter, the attack, release, hold etc. can be used to compromise between peak and RMS settings.
4. Playing predominately prerecorded electronic music, which often has bass with 3 dB(or even less) dynamic range, you seem to be missing the "elephant in the room"- average power. The average level for a driver like the B&C 21SW152-4 should probably be in the 400 watt range (10 dB less than it's peak rating!), only 40 volts or so to avoid cooking the voice coil.
Fortunately, between the Powersoft k10 and the Venu360 you have plenty of options available that won't require sacrificing peak potential for long term heat management.

Have fun on the 8/15/19 weekend, keep those driver's magnets below the boiling point of water ;^).

Art
Here is my "quick go to" for thermal limiter settings.

That driver is rated for 2000 watts @ 4 ohms, which is 89.5V.

My "go to" is 6dB lower, or 1/2 the voltage., so 45V.

So only 0.5dB higher than Arts 40V.

Of course B&C rates the power at the referenced to the minimum impedance, not the "nominal" impedance.  So they get a little bit higher rating than nominal, based on the drive voltage.

So if they used the nominal impedance, the wattage rating would be lower, and therefore the limiter setting would be lower, closer to Art's number.

It "all depends" on how you calculate it------------
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Ivan Beaver
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Re: Users of dbx venu360 could use some help with the limiters
« Reply #6 on: August 08, 2019, 03:37:18 pm »


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