Do i need a Beringer Feedback Destroyer ?

[jonnyv]

Below is a graph of my rel q100 sub taken using spl meter.

Its been a while since i took any readings, and the first readings ive taken in my new house.

Im thinking of getting a BFD and wondered what people thought of my graph and how to improve it with a BFD ?

I can see that most frequencies need to be dropped by 15db for 16hz and 22db for 36hz etc...

Readings taken at reference level 00 on amp previously set to 75db on all channels, test with sub only.

[chrisgeary]

firstly i would suggest taking measurements at -30db or -25db rather than 0 as 0 ought to be too high to be firing sine waves into your sub. it is possible to burn out voice coils with sine waves. i typically get readings between 75 and 85db.

secondly, it would be helpful if you could measure all the way to 160hz to give us some idea of the rest of your room response.

thirdly, purely based on what i see in that graph, i would say yes, buy a BFD and
cut 12db @ 40hz approx bandwidth 5.
cut 10-15db @ 80hz approx bandwidth 5.

i suspect, though, that once we see what is going on above 80hz, that these suggestions will be largely invalid. either way, a BFD is going to help you out for sure.

Chris

[IronGiant]

I had just the same problem, a BFD sorted it, see post 49 in this thread

RELinquished finished

blue before and purple after BFD and a granite slab on top

Dave

[jonnyv]

Thanks for the replys..I may concider buying one in that case.

dos it make that much of a difference to the sound of the subwoofer ?

[IronGiant]

Definitely, my peaks at 40 and 80 dominated everything, I had to run the sub at such a low volume to minimize boominess caused by those peaks I got very few low frequency effects at all. If I recall correctly I did similar to what chris suggested and the wobbles higher up dissapeared without needing anything extra.

Dave

[Mr Incredible]

I personally like the flat green curve for all my sources, movies and music. The sub sounds more controlled, tight and very little colouration in its reproduction. Without the BFD the sub sounded over bearing, boomy and loose in the lower frequencies.

It is worth the investment and time to set it up right!