I was hoping to get some advice on the limiter settings for a Crown XTI-4002. I have upgraded to this amp from a xls2500 drivecore and am yet to try it in a live environment. The amp and speaker specs are listed below.
Crown XTI 4002 - Running 650w @ 8 ohms
2x FOH - Yamaha R115 8 ohm- pgm 500w, peak 1000w
I am thinking about putting the peakx limiter setting to maybe -1 or -2db due to the poweramp being a slightly highter wattage than the speakers. Would this be the right thing to do, or would it be okay just to run it at full 650w? I won't be there for the night but I believe the bands will be playing rock genre.
Thank you for your advice
Note that even when setting the limiters correctly, you only protect the speakers against thermal overload and that works only for the biggest driver in the cab. To also try and protect it against mechanical overload you need to also set the High Pass filter in the amp to the correct setting in accordance with your speaker specific frequency response (-3dB point).
If P is the power limit in watts, Z is the driver's nominal impedance in ohms, and G is the amplifier gain in dB (not dBu!), the limiter threshold in dBu is just 10*log(P*Z/0.6)-G
The XTI takes dBfs
units and not dB or dBu, dBfs units are always negative, in relation to the amps max power, the maximum power output of the XTI at 8 ohms 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
One more note, that we didn't take power compression into account, only LF driver damage. If you want to protect against that as well, you need to further limit your speakers to 1/2-1/4 of the RMS spec, that's 65-125W (I know it sound allot but try it).
10XLog(P1/P2)=10XLog(65/650)= -10 dBfs