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XTI 4002 limiter setting


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#1 debzdoodle

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Posted 26 July 2013 - 04:20 PM

I am never really sure where to set my limiters and was hoping I could get some help?????.

I have been using my XTI4002 in stereo for my 2 SRX 715s. I'd like to have the option of using the amp bridged into 4 ohms on occasion when I need just a little more headroom (this has only happened once -we play small venues).
I use a DRPA also. What limiter settings should I use to protect my speakers increasing from 650w per side to 1600w per side (in theory)?

DBX DRPA+
2 x XLS2000 (bridged) - SRX718
1 x XTI 4002   - SRX715 (mid)
1 x Carvin HT760 - SRX715 (horns)

Thank you in advance !!!!

#2 dakos

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Posted 27 July 2013 - 07:24 AM

Since the XTi2 has only one limiter per channel you can either protect from Peak OR RMS wattage OR against clipping, not all, so what we do to trick the amp into doing RMS and Peak is first choose an amp that has about the maximum wattage rating as the Peak rating of our speakers, by choosing correctly we're indirectly, so long as we don't clip the amp, is setting sort of a Peak limiter, now we need to set the actual limiter as an RMS limiter.

The RMS setting is done like explained in the following link:
http://forums.prosou...hp?topic=5229.0
Avi

#3 debzdoodle

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Posted 29 July 2013 - 02:53 PM

Thank you for the response Dakos. However, I am not understanding the formula used here:

The XTI takes dBfs units and not dB or dBu, dBfs units are relative to the amps max power, the maximum power output of the XTI is 650W, that equals 0 dBfs. Your speakers are continuous (RMS) 250W (pgm 500W, peak 1000W), from here it's just a plain dB ratio formula, you get:
10 X Log(P1/P2)=10XLog(250/650)= -4.15 dBfs.

The last part doesn't make sense to me even using the OP amp ratings. I tried the math but cannot get the same result. I need gentle guidance !!!

#4 dakos

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Posted 30 July 2013 - 04:51 AM

The 715s woofer is able to take 3200W Peak but the Xti 4002 can "only" make 1600W per driver, so we don't need to worry about peak power (as long as you don't clip the amp which is still possible when configuring the limiter as an RMS limiter). For continuous power I would recommend limiting to about 250W per driver or even less (but I'll show you how to calculate using these numbers), that's 500W total from the amp.

So using our formula with the current numbers:
10 X Log(P1/P2)=10XLog(500/3200)= -8.02 dBfs.
That's the number you enter the amp.

If you're still having trouble, let me know...
Avi

#5 itech6k

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Posted 30 July 2013 - 04:49 PM

View Postdakos, on 30 July 2013 - 04:51 AM, said:

The 715s woofer is able to take 3200W Peak but the Xti 4002 can "only" make 1600W per driver, so we don't need to worry about peak power (as long as you don't clip the amp which is still possible when configuring the limiter as an RMS limiter). For continuous power I would recommend limiting to about 250W per driver or even less (but I'll show you how to calculate using these numbers), that's 500W total from the amp.

So using our formula with the current numbers:
10 X Log(P1/P2)=10XLog(500/3200)= -8.02 dBfs.
That's the number you enter the amp.

If you're still having trouble, let me know...
Avi

What attack and release times would you use for average power protection?

I just bought a couple xti2's and am in the process working on the limiters.

#6 dakos

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Posted 31 July 2013 - 03:21 PM

I don't understand the way your whole rig is connected nor why you have so many amps nor why you bought more new ones or why you chose XTi, if you want post your entire rigs topology and I'll see if everything is set up properly.

Back to our issue, a good starting point is a 1 second attack and 6 second release.
Avi