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Power amp cutting out. Why?

Posted: Tue Feb 12, 2013 4:46 pm
by CT
Equipment being used.
TLAH Pro 8 ohms x 2
T48 15LF loaded
QSC RMX1850 DCX2494
BEHRINGER Mixer
15 band EQ

The amp clips constantly and cuts out intermittently at high volume with singers and keyboard in a church setting even though the mixer is not clipping. If the mixer is turned down to prevent the amp from clipping the overall volume will be too low. Any ideas as to how to solve this problem?

Re: Power amp cutting out. Why?

Posted: Tue Feb 12, 2013 4:57 pm
by Ryan A
There could be a short in one of the speaker cables or cabs?

Re: Power amp cutting out. Why?

Posted: Tue Feb 12, 2013 7:35 pm
by Bas Gooiker
Without clipping the output of the mixer, your output gain from it could well be to high for your amp and clip it.

Could still be asking to much of your setup. I dont know how big the church is, but the 300w into your titan might not be enough to fill a big room.

Re: Power amp cutting out. Why?

Posted: Tue Feb 12, 2013 11:02 pm
by Grant Bunter
Bas Gooiker wrote:Without clipping the output of the mixer, your output gain from it could well be to high for your amp and clip it.
+1
Also, if you increased the output and input gains on the DCX in order to balance the TLAH's with the T48, set them all back to 0 and use the limiter on the TLAH output channel to balance instead. This also frees up the CPU somewhat in the DCX. As does removing any EQ and using your 15 band for that job.
Bas Gooiker wrote:Could still be asking to much of your setup. I dont know how big the church is, but the 300w into your titan might not be enough to fill a big room.
50V @ 10 ohms = 250W, so 300 should be ample. I can't see a church wanting a T48 at war volume, but if there is only one and the church is large, I can see your point.

Re: Power amp cutting out. Why?

Posted: Tue Feb 12, 2013 11:05 pm
by BrentEvans
Grant Bunter wrote:I can't see a church wanting a T48 at war volume, but if there is only one and the church is large, I can see your point.
Never underestimate what can happen in church. :shock:

Re: Power amp cutting out. Why?

Posted: Wed Feb 13, 2013 10:28 am
by Zack Brock
CT wrote:Equipment being used.
TLAH Pro 8 ohms x 2
T48 15LF loaded
QSC RMX1850 DCX2494
(...)
The amp clips constantly and cuts out intermittently at high volume with singers and keyboard in a church setting even though the mixer is not clipping.
Which side is clipping and cutting out? I assume you are using one channel of the RMX1850 for tops and one for subs?

Re: Power amp cutting out. Why?

Posted: Mon Feb 25, 2013 9:03 am
by CT
Zarunning ngock wrote:
CT wrote:Equipmentlookingking used.
TLAH Pro 8 ohms x 2
T48 15LF loaded
QSC RMX1850 DCX2494
(...)
The amp clips constantly and cuts out intermittently at high volume with singers and keyboard in a church setting even though the mixer is not clipping.
Which side is clipping and cutting out? I assume you are using one channel of the RMX1850 for tops and one for subs?
The side. running the tops is clipping. After looking at the setup closely it appears that I was driving the amp inputs with too much levels from the EQ.

Re: Power amp cutting out. Why?

Posted: Mon Feb 25, 2013 7:26 pm
by Gauss
I discovered that on my Crown XTi1000, when I clip my sub output, the top output distorts through my top speakers. The top channel is not clipping. Weird. I have no idea if the sub is distorting, the Titan doesn't sound any different and I don't expect any of the noises to be able to come through the folds.

Re: Power amp cutting out. Why?

Posted: Mon Feb 25, 2013 7:36 pm
by Bill Fitzmaurice
Gauss wrote:I discovered that on my Crown XTi1000, when I clip my sub output, the top output distorts through my top speakers.
Probably the power supply is hitting its limits, and that reduces headroom in the other channel as well.

Re: Power amp cutting out. Why?

Posted: Tue Feb 26, 2013 6:29 am
by Bas Gooiker
Did you check the wiring on the Tlah? The resistance load of the array?