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Author Topic: Odd ITECH limiter behavior-Or- how to set them? Users?  (Read 26578 times)

Ivan Beaver

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #50 on: August 03, 2011, 08:34:02 AM »

Well I was about to post "I dont know what your caught up on Ivan, my measurments are fine."
I was using the Tektronic Osc at work today and realised what I thought was my Peak readings were actually Peak to Peak readings. The RMS should have been right still but I will need to check everything again.

If what you have discovered is true though, I'm not real happy about it. You spend tens of thousands on amps that have DSP in them that isn't true. I dont want to have to adjust my settings after the amount of money I've spent. 100 Volt limit setting should equate to 100 Volt limit.
I hope there is a silver lining to all this.

EDIT:
No, My measurements were right the first time. I did realise at the time it was Peak to Peak. I tried higher voltage thresholds this time and I'm getting the same result, not as tight, but still very close. With music as source the Rms and peak voltages were not far from set values. They were not falling short, sometimes exceeding thresholds momentarily.

I'm not sure on the product any more though after the depth Ivan has gone and found differences. Very interested in what the Crown factory had to say.
Apparently with a limited bandwidth (such as with bi and triamped systems) the limiters are closer to what the value says.  But with full range systems, "something" is going on.

I guess they are just trying to protect us from ourselves.

Just to rule out a possible bad amp-today I going to putting values into a whole bunch of them and see what I measure on the output.  And get to play with the truly manual mode.
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Ivan Beaver
Danley Sound Labs

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Mario Roman

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #51 on: August 03, 2011, 10:17:48 AM »

Apparently with a limited bandwidth (such as with bi and triamped systems) the limiters are closer to what the value says.  But with full range systems, "something" is going on.

I guess they are just trying to protect us from ourselves.

Just to rule out a possible bad amp-today I going to putting values into a whole bunch of them and see what I measure on the output.  And get to play with the truly manual mode.

Ivan,

I'm looking forward to the results of your testing as after watching this thread since it's inception, I'm pretty sure I don't have the limiter settings in the ITech 8000 that's powering my pair of TH118's set properly. Hopefully I can figure out how to set it right after you've completed your testing. Thanks for doing the research and enlightening us.

It almost seems that running a PL380 through one of these:    http://www.eminence.com/d-fend/
would be allot less hassle than using a DSP amp. And from what I've read if their claims are true, it may provide better driver protection. Just a thought....

Mario
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Ivan Beaver

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #52 on: August 03, 2011, 10:01:55 PM »

Ivan,

I'm looking forward to the results of your testing as after watching this thread since it's inception, I'm pretty sure I don't have the limiter settings in the ITech 8000 that's powering my pair of TH118's set properly. Hopefully I can figure out how to set it right after you've completed your testing. Thanks for doing the research and enlightening us.

It almost seems that running a PL380 through one of these:    http://www.eminence.com/d-fend/
would be allot less hassle than using a DSP amp. And from what I've read if their claims are true, it may provide better driver protection. Just a thought....

Mario
We tried 3 different amplifiers with 3 different passbands and none of them came up with the correct numbers-using the  "unlocked" access that Crown gave us.

We have numnber that will work-but the voltages are a good bit off from what they should be.  BTW there were 5 audio guys there-ranging from very experienced to genius with about a decade and a have experience. We were all "stumped".

We will be going back to Crown to figure this out.

The Defender looks like a good idea-if it works without knowing it is "working".

I am supposed to get samples when they are getting close to production, to play with.  Yes it looks like a VERY good idea.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

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TJ (Tom) Cornish

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #53 on: January 16, 2014, 11:29:29 AM »

We tried 3 different amplifiers with 3 different passbands and none of them came up with the correct numbers-using the  "unlocked" access that Crown gave us.

We have numnber that will work-but the voltages are a good bit off from what they should be.  BTW there were 5 audio guys there-ranging from very experienced to genius with about a decade and a have experience. We were all "stumped".

We will be going back to Crown to figure this out.

The Defender looks like a good idea-if it works without knowing it is "working".

I am supposed to get samples when they are getting close to production, to play with.  Yes it looks like a VERY good idea.
Any update on this thread?  I'm looking for TH118 settings for ITHD12K and would love to know what was at the end of the rabbit hole.
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Tim McCulloch

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #54 on: January 16, 2014, 12:49:53 PM »

Any update on this thread?  I'm looking for TH118 settings for ITHD12K and would love to know what was at the end of the rabbit hole.

A rabbit.  Or several rabbits. ;)
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David Sturzenbecher

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #55 on: January 16, 2014, 01:05:08 PM »

A rabbit.  Or several rabbits. ;)

FWIW, I used an IT5000 on a DBH18 (one channel per driver), plugged in 62V in for the RMS limiter, and got out 63V as measured with a sine wave and a fluke meter. That was close enough for me.
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Ivan Beaver

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Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #56 on: January 16, 2014, 06:55:26 PM »

Any update on this thread?  I'm looking for TH118 settings for ITHD12K and would love to know what was at the end of the rabbit hole.
Good question.

A little while back one of the other guys was doing a setup and when he measured the output voltage it was VERY close (like within a volt or so) of what the settings said.

HOWEVER a little bit after that I used the same meter (HP400) to measure a ITECH HD that we had in the shop and it was off a fair bit.  I check my meters (I have a couple of HP400s and others) kinda often and they are reading the same-or at least close enough for me not to worry.

Not as bad as with the ones with different software-but still off-and a bit more than what Chad had measured.

Some Crown engineers told me (back when I first having issues) that the actual gain of the amp could vary by a couple of dB, and that the limiter had no reference to the output.  It was acting like a stand alone limiter in front of the amp.  Even though the block diagram says different.

So if the gain of the amp is varying a couple of dB, then that could throw off the numbers in the DSP.

So I am a firm believer in MEASUREMENT.

I have a feeling a change was made in the software (as I have heard through the grapevine that I was not the only one complaining about it)

So make of it what you will.

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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

ProSoundWeb Community

Re: Odd ITECH limiter behavior-Or- how to set them? Users?
« Reply #56 on: January 16, 2014, 06:55:26 PM »


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