# Defective BFD, or Input Level too low?



## Guest (Feb 6, 2008)

I've gone through 2 complete calibration sessions with the same results --- my before and after measurements are identical. The BFD has no affect. (Note: While trying to debug this issue I made some drastic changes to filter settings to see if I could force any kind of a change. Nothing changed.)

One consistent parameter is that I have a low level to the BFD --- no more than 2 LED's light up at maximum listening levels. Is it possible that the BFD will bypass it's internals with too low of a level?

Is there a simple test to see if the BFD is defective?

Thanks in advance for any help...............


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## brucek (Apr 11, 2006)

> Is it possible that the BFD will bypass it's internals with too low of a level?


Nope...



> Is there a simple test to see if the BFD is defective?


Sure.
1. Feed a single 50Hz SINE WAVE from REW Signal Generator and observe the VU LED as to which channel it is using. Hear the tone in your system.

2. Ensure the IN/OUT LED is solid green.

3. Select Program 4 (it's as good as any). Select filter #1 and use mode PA and ensure the filter#1 LED lights up to show it's active. (Be sure it's active on the channel you're using left or right or both)

4. Select 50 Hz (not .50 KHz). Select BW of 10.

5. Adjust the GAIN down to -48dB and hear the tone go very low in volume. To store the filter double click the flashing store button (not that you want to though).

brucek


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## Guest (Feb 7, 2008)

Thanks. OK, I have verified that the BFD is working.

I started with your 80Hz filter I found in another thread. Here's my results with my sub's xover set at 75 hz and 150 hz. My receiver's sub xover is set to 60 with front speakers set to large. Please note that all speakers except for the sub were off for these tests. 

Where do you think I should go from here? I'm concerned about the 100-200hz hash because it does show up at higher levels when all speakers are on. I ran sweeps with the receivers xover set to 80 and 100 with simliar results.

Thanks in advance...................


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## brucek (Apr 11, 2006)

Note: When you post graphs, use a vertical scale of 45dB-105db and a horizontal scale of 15Hz-200Hz 



> my sub's xover set at 75 hz and 150 hz. My receiver's sub xover is set to 60 with front speakers set to large.


You have a very bad situation there. You *never* use the subs own crossover when you are using bass management in the receiver. So, for starters, either disable (some subs offer this option) or dial your crossover in the subwoofer itself as maximum clockwise as possible, so it's not in the mix.

Next, set your mains to small. It doesn't matter how 'large' you feel they are, you must set them to small to take advantage of the intent of bass management. 

Then set you receivers subwoofer crossover to 80Hz for a start. Then when you do a measurement of the sub and mains, they will usually combine nicely and you can play a bit with the subs phase control to get the best transition at the crossover region.

See the pic below... this is what happens when you set the sub and mains crossover the same. The red line shows the combined output of the crossover area. Yes, that's a system made in heaven, but you can come close. BTW, your sub response is quite good.










brucek


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