# Audible Clipping, but LED's still green/yellow.



## tyler durden (Jan 6, 2009)

I am just setting up my BFD, and having set the input level and applied REW recommended filters I am testing it out at louder volumes.

I have noticed an audible clipping noise coming from my sub, which disappears when I take the BFD out of the system.

I have not noticed the LED's going up to the red, but is it possible it is clipping without showing them?


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## Wayne A. Pflughaupt (Apr 13, 2006)

No, the BFD won't clip unless the meters hit the red. However, it could be that your sub's amplifier is clipping, or that the driver is hitting its limits (bottoming out). You have to keep in mind that equalizing places additional demands on both the driver and amplifier, so you have to have ample headroom going in.

Regards,
Wayne


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## tyler durden (Jan 6, 2009)

Thanks for the reply.

If the driver (AE AV15-X) or amp (Behringer EP2500) were reaching their limits, why do I not hear the sound when playing at higher volumes without the BFD in the system?


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## Wayne A. Pflughaupt (Apr 13, 2006)

tyler durden said:


> If the driver (AE AV15-X) or amp (Behringer EP2500) were reaching their limits, why do I not hear the sound when playing at higher volumes without the BFD in the system?


Answered in prevous post:





Wayne A. Pflughaupt said:


> You have to keep in mind that equalizing places additional demands on both the driver and amplifier, so you have to have ample headroom going in.


IOW, if you take the BFD out of the system, you remove the equalization. Therefore you now have additional headroom.

Regards,
Wayne


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## tyler durden (Jan 6, 2009)

Okay, I think I understand now, but the driver moves a lot more when playing at the high volumes without the BFD, so I assume it isn't bottoming out when the BFD is in place.

I'll check the amp, but I would have assumed that as it is running in bridged mode and giving 2400w of power, that it would be unlikely to be running out of steam!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Actually, that might be part of the problem. It's fairly well known that running an amplifier bridged into its minimum-rated load is the most strenuous and demanding of conditions that you can place on it. 

It's pretty easy to tell when a driver reaches its limits. The VC bottoms out an you hear all kinds of rude popping and/or clunking noises. The amp is a bit trickier. If you aren't seeing (or rather hearing) an indication that the driver is maxed out, try turning the volume down a bit; if the unpleasant noises you're hearing go away, then it's probably the amp that's giving you problems.

Regards,
Wayne


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## lsiberian (Mar 24, 2009)

The Behringer EP2500 is capable of driving almost any load. The driver or design may be to blame for the issue. If the driver is ported eqing must be done with caution. Or you can bottom out the driver quickly.

Check for air leaks in your sub and use silicone caulk to seal that box and the driver/box join up good. I suspect an air leak may be the cause of your problems.


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## tyler durden (Jan 6, 2009)

It's a sealed box at around 80ltrs, and I cannot feel any air leaks.

Also, if it were a leak, would the BFD make any difference? Without the BFD it can play a lot louder with no sign of problems.


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## Wayne A. Pflughaupt (Apr 13, 2006)

I don't see how the BFD would make a difference if leaks are the issue.

BTW, is this happening at your regular viewing levels, or just when you try to push things to the max?

Regards,
Wayne


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## tonyvdb (Sep 5, 2007)

It could also be that you are clipping the input of the BFD or the amp. If your input level is too hot that can also cause clipping.


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## lsiberian (Mar 24, 2009)

tonyvdb said:


> It could also be that you are clipping the input of the BFD or the amp. If your input level is too hot that can also cause clipping.


This is a good point. I don't see output as the problem here.


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## tyler durden (Jan 6, 2009)

Wayne A. Pflughaupt said:


> I don't see how the BFD would make a difference if leaks are the issue.
> 
> BTW, is this happening at your regular viewing levels, or just when you try to push things to the max?
> 
> ...


It only happens when pushing towards reference level.




tonyvdb said:


> It could also be that you are clipping the input of the BFD or the amp. If your input level is too hot that can also cause clipping.


But wouldn't that be seen in the LEDs?


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## tonyvdb (Sep 5, 2007)

tyler durden said:


> But wouldn't that be seen in the LEDs?


No, that would not show up on the LEDS of the BFD or the sub. I clipped my input of the EQs for my mains once during the Hulk all I did was back off the output level from the receiver and all was well.


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## ToBeFrank (Feb 27, 2010)

tonyvdb said:


> It could also be that you are clipping the input of the BFD or the amp. If your input level is too hot that can also cause clipping.





tyler durden said:


> But wouldn't that be seen in the LEDs?


To see if you're clipping the input, put the BFD in bypass mode. The BFD LEDs switch to showing the input level in that mode. Then play the same material at the same level as where you're having the problem.


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## Wayne A. Pflughaupt (Apr 13, 2006)

tyler durden said:


> Wayne A. Pflughaupt said:
> 
> 
> > BTW, is this happening at your regular viewing levels, or just when you try to push things to the max?
> ...


Is that a "yes" for normal viewing levels, or a "yes" for pushing things to the max?

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

tyler durden said:


> But wouldn't that be seen in the LEDs?


If you're seeing clip lights on the EP 2500, that would mean that you're overdriving its inputs. If that's the case, you can reduce the amp gains and still drive the amp to its maximum output.

Regards,
Wayne


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## brouham (Sep 3, 2009)

I vote for the input signal clipping of the BFD or amp. I had the same problem but the input clipping caused my sub amp to distort and then go into protect mode (shut down). I increased the input setting on the BFD from -10dBV to the +4dBu setting and all was fine afterwards; I was able to play the sub at very high levels without any problems.


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## tyler durden (Jan 6, 2009)

I have now sorted this issue. It was the input level that I needed to lower.

Thanks all.


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## Ricci (May 23, 2007)

Perhaps the SW pre-out is clipping heavily? Either that or as Wayne has said the amplifier is clipping or the driver is making noise due to EQ boosting.


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## soundguy2856 (Mar 20, 2008)

Anytime you use digital Eq you must account for the gain you add by first taking loss at the input. It can be a difficult task to determine dynamic headroom in a system. Try taking each section at a time. Since the clipping ceases when you bypass your EQ I sould look at the gain staging there.


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