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I-tech RMS Limiter and other questions


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#1 Sidhu

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Posted 09 November 2012 - 02:47 AM

Hello!

Clarity on a few questions I would greatly appreciate. Thank you.
Situation where we are trying to Drive a single box VRX932@8ohms vs. 2@4ohms.
First.

The peak limiter are in Volts, so that would remain constant irrespective of combined load. For the VRX932 with a programmae rating of 1600w I would set them at about 110v. Correct ?

For the RMS limiter, do we need to constantly change the value to the combined load of the speakers. Say we have one box a side at 8ohms with a cont. rating of 800w, then set the RMS limiters to maybe bout 400w.

If we have two boxes a side driving the amp to a 4ohm load, but a combined wattage of 1600w, then tweak the RMS limiters to say bout 800w ?>

Is this correct ?

Regards,
Sidhu

#2 dakos

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Posted 12 November 2012 - 12:46 AM

Dear Sidhu,
Sorry for not getting back to you earlier, I was away for the weekend.
So, you can either recalculate each time you connect the speakers differently or you can create custom presets for each configuration and just switch between them. The custome presets contain much more then just limiter settings so that's a very time saving feature.
All the best
Avi

#3 Sidhu

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Posted 13 November 2012 - 06:24 AM

hello Avi!

No apologies needed. Many thanks for reverting!

So my input parameters are correct ? And I understand just making different presets.

If I am not mistaken, the iTech-HD series now input RMS limiter values also in Volts ?

Tx again!
Sidhu

#4 dakos

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Posted 13 November 2012 - 07:05 AM

Since you talked about watts value for RMS limiter settings I assumed you were talking about older non HD version of the itech, on the HD series it's simpler with volts as input. Which one do you have?

#5 Sidhu

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Posted 14 November 2012 - 06:15 AM

Oh I dont have any. but work on both Itech's and IT HD's regularly. So just wanted to get the math correct. Vendors around here dont address their limiters.

Next.

Input senitivity should be set to the console output sensitivity correct ? Or the DSP feeding the amps.
Output level on the X32 is 21dBu, and on the SC48 is 24dBu etc. This should corelate my metering up ?
If i dont have console specs available, then setting the sensitivity to 26dBu should work none the less.

On the old Itechs I have the option of maximum input of 15 or 21dBu, along with input sensitivity which has a wide range.
On the HD i have two presets for 26/32 dBu along with a custom panel which resembles that of the older Itechs.

What should these be set to ?

Basically im not understanding the input sensitivity functions and how they work. What if I have 2 amps on the same rig with different parameters ?

Tx again!
Sidhu

#6 dakos

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Posted 15 November 2012 - 02:56 PM

Dear Sidhu,
If you use the internal amps DSP the input sensitivity doesn't matter that much except for one things that come to mind, you want to incorporate the input sensitivity into the gain structure of the entire rig so nothing gets over amplified so it's clipping or amplifying too much floor noise. Other companies have different philosophy about gain matching and the itech can work with those systems as well since it has allot voltage gain settings, 149 on the NON HD version, most of them are only available using System Architect.

#7 Sidhu

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Posted 16 November 2012 - 10:11 AM

Thaks a ton again Avi!

what happens when We are not using the amps DSP. and the amps are then still running different sensitivities ? Is it akin to having the input trims at different levels ?

I dont have any amps at hand to try, so excuse my asking.

tx,
Sidhu

#8 dakos

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Posted 16 November 2012 - 10:36 AM

That depends on the philosophy of the specific vendor, I know Peavey\Crest are fanatic about this, any way it doesn't really matter which philosophy you use as long as you impliment it correctly. If you take the gain down too much so you have to push the mixer too much to compensate then obviously this is not good, you might be clipping the mixer. The other way around has other faults as well so keeping a proper gain structure is very important. Look here for more info on gain structure:
www.youtube.com/watch?v=1hwT15SSwgU
or this one:
www.youtube.com/watch?v=tornRFVtGxI

#9 Sidhu

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Posted 16 November 2012 - 11:44 PM

Tx a ton Avi!

You have been of great help!

Sidhu