QSC amplifier clipping at low volumes

[TheChick3n]

I have a QSC RMX 850 (not the 850a) and I have it set to stereo mode with channel 1 for the mids and highs and channel 2 for a subwoofer.
I do have a crossover setup correctly

So the problem occurs when there is a lot of bass playing and I try to turn it up. The signal LED is barely lighting up when the clip LED turns on and there's a major crackling noise from the speakers. Doesnt sound like 270 watts (240 watts in the manual?)

The mids and highs are a Peavey TLS 6X @ 4Ohms and the sub is a Peavey Black Widow 18" in a custom enclosure @ 8? Ohms

I'm not sure what's going on, any help or would be appreciated.
Thank you in advance.

 

[Ironsounds]

Hello... 1) Does the same thing happen without a cable and signal at the Input?
2) Switch channels out.... same thing happen?
3) Switch inputs.... same thing happen?
4) Passive or Active x-over crossover setup?
5) Try using the amp like a typical stereo Amp with a different set of speakers... same thing happen?
6) What level is your Input signals at?
7) What are you using fo drive the Amp?

Typically you want you want a High and Low mono signal input for each channel. channel 1 to be your Highs output and channel 2 your LOW output. this would be a "Active 2 way"

 

[TheChick3n]

The amp only does this with audio playing. If there are no inputs with gain set at its highest lever, all you'd hear is a soft hissing sound.
Switching the channels and inputs did the same thing.
I have an active crossover in stereo mode, but I'm only using the left output of the X-Over
Also, the TLS 6X still has its built in passive crossover.
Unfortunately, I don't have another set of speakers that can handle it's power for they are only 120 watts each..
I have the playback device playing at 100% volume going to a mixer which outputs to an EQ through a mono output.
from the EQ goes to the crossover then to the amp.
The crossover has both mids and highs on a single output.

Thank you!

 

[americanaudiophile]

It may be possible you are overloading the input of the mixer, EQ, or the amplifier. Try lowering your playback device volume Try turning the mixer output level down. Try setting the gain of the amp down.
The clip indicator may be coming on because it is detecting the input overload distortion not output distortion.

 

[Ironsounds]

Hello... The point being... What component creates the Output amp overload... try to ISOLATE... add one thing at a time.

Are you using a MP3 player headphone Stereo output to high/low/MONO level mixer input? This is improper Signal/Input/Impedence matching!!! and the result could be what you are seeing/hearing... Try a Microphone input OR LINE level Output ( Audio/Tape OUT from a Reciever ) to the Mixer Channel/Channels and see if the same thing happens.

Get the QSC manual/pdf out... there are a lot of "Dipswitch Settings" on it that need to be set for a "High/Low BIAMP" type of setup. ( the pictures are really good in it ).

1) Speakers can cause this
2) Or an Improper Impedence/High level input.
3) Or a Bad shielded/shorted input Cable.
4) Or Improper 2/3 pin Input connector/adaptor. ( Dipswitch setting for single/dual channel READ/Active input )
5) Or Dipswitch setting for Bridge/MONO/dual channel Output.
6) Or Dipswitch setting for Overload/Freq/Speaker Protection.
7) Or the Amp is Bad.

I have two QSC's and the main thing that is confusing to me is getting those small Dipswitches set right, When I have to change a Wiring situation Fast for a show.

 

[TheChick3n]

In response to Americanaudiophile:
the mixer has a headphone jack output also, and when I use me headphones, the audio sounds clean, and there are no clip LEDs Turing on at all. the EQ and crossover both have clip LEDs which are not turn in on either at the time when the amp clips. the gain on the amp is 16dB for channel 1 (mids/highs) and 18 for channel 2 (subwoofer)

To Ironsounds:
I have my playback device connected to stereo input on my mixer. I then use the mono output to connect to the EQ through XLR cables then to the left crossover input (also XLR) then you know where the mids/highs and lows go from there.
another thing is that whenever there isn't so much bass playing, I am able to get louder on mids/highs. it can't be the amp either because I was able to play full range bridge mono with no problems.
I have double checked the dip switches, they are all in the right position.
When I got the cabinet, one of the woofers had a piece of metal in between the magnet and the voice coil. the woofer does play like normal, even with an 80 watt amp that I have.

 

[Ironsounds]

Hello... It sounds like you have a BAD speaker with more "Metal/Debri" that could have "Shorted/Damaged" your voice coil windings, AND be Shorting your AMP output... AND your amp is going into "Protection Mode".... Like it should B )

 

[TheChick3n]

Hello... It sounds like you have a BAD speaker with more "Metal/Debri" that could have "Shorted/Damaged" your voice coil windings, AND be Shorting your AMP output... AND your amp is going into "Protection Mode".... Like it should B )

that seems to be the problem, and ill unplug the damaged woofer when I get a chance, but how is it that they can get louder at some points when there isn't a lit of bass? Also, if I do unplug that one woofer, is there anything that I should be careful with (other than making sure the terminals don't short)?

Thank you for your help!

 

[Ironsounds]

Hello... Unplug the wires from the AMP too?