# BFD 1124 Low Frequency Noise - 2 subs



## Bigdaddy999 (Nov 12, 2006)

Hi all. Need some suggestions on how to track down a problem in my rig. Pre-Pro / runnign a pair of matched subs using line-level connections.

The subs are wired as follows:

Anthem AVM 20 Pre-Processor LFE (sub) - out split to L & R channels on the BFD.
RCA-> Phono plug inputs

RCA-outs to the subs

BFD filters set using REW and programmed to lock both channels together.

Problem 1

What I've noticed is this. When I have ANY source playing (even something like choral or piano with minimal low end), once I reach a certain volume, there is a continuous very low frequency noise (not a 60hz hum - more like 20hz rumble) in both channels. I can feel it on the woofer drivers, and can hear/feel it if they're really cranked up. Both channels show the green LED's at level 1, if that makes sense. If I eliminate the filters on the BFD, it goes away completely, and the lights go out, along with the noise. Same behavior on any presets I have set up.

I'm thinking that this is a problem within the BFD someplace, but wasn't sure where to start looking.


Problem 2

Also - and this is probably a separate issue, when the In/Out switch is dark, I get different readings on the LED levels, but if solid green or flashing, they're locked together. Is that normal?


Thanks for any suggestions.


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## Dale Rasco (Apr 11, 2009)

I had an issue with something similar and when I turned off the 1124, the noise went away. I was able to identify the problem rather quickly as being a grounding issue with my new rack. I had forgotten to ground the metal rack when I installed it a couple of weeks ago so once I did that, the problem was gone. 
A couple of questions:

Does the problem continue when the 1124 is off?
Does it happen in both subs?
What type of power conditioner are you using?


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## Bigdaddy999 (Nov 12, 2006)

Good morning.

Does the problem continue when the 1124 is off?
Does it happen in both subs?
What type of power conditioner are you using?

Respectfully, the sub output is zero when the 1124 is off.
Yes - both subs rumble or neither.
Power conditioner is a Belkin PureAV PF60

Thanks!


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