input level, and roll off

[eddthompson]

Hi, set up the bfd with rew for today, unfortunatly on an offline computer so i cant post the graphs.

First off, to get the sub output level high enough to light up the lights on the bfd, i had to set all the speakers 10db lower than usual, and the sub 10db higher, then compensate on the sub amps gain, still most of the time the only light appearing is the -40db light, will this be a problem?

I also get a roll off starting at 30hz, this is pretty steep, is it worth trying to compensate for this? or should i leave it be until i can build my own monster sub.

current equipment:
denon avc-a1se
b&w pcs8 http://www.bwspeakers.com/downloadFi...el/ACF2679.pdf
powered by a behringer ep1500.

on the specs the -3db point seems to be 35hz, so the roll off from 30hz seems about right.

on a side note, eq i get a pretty much flat responce from 30-80hz, just need to perhaps add a room curve.

edd

[brucek]

also get a roll off starting at 30hz, this is pretty steep, is it worth trying to compensate for this? or should i leave it be until i can build my own

No, the sub seems to be within spec, so throwing more voltage at your sub amp won't do anything positive for you.

still most of the time the only light appearing is the -40db light, will this be a problem?

Is this during normal listening material or when using REW? If you play a single 50Hz sine wave with REW once it's setup for measurement, does the level getting to the BFD seem better?

brucek

[eddthompson]

normal listening, with the input to the bfd from the denon.

from the laptop directly into the bfd, bypassing the denon, the green bars lit to -10 or so, about what a base heavy dvd goes to at maximum listening level, ie the opening sequence of toy story 2.

i guess ill just have to get another sub if i want to go lower, it certainly extends down to 10hz according to rew, but at about the -30db point. being a sealed sub i guess you would expect this.

edd

[brucek]

from the laptop directly into the bfd, bypassing the denon, the green bars lit to -10 or so, about what a base heavy dvd goes to at maximum listening level, ie the opening sequence of toy story 2

That's fine....

brucek

[eddthompson]

Thanks alot, ill try and post graphs at some point for reference.

Got to admit im surprised how much difference its made, sounds superb now.

edd

[eddthompson]

graphs for reference, before :



after:



this was straight into the bfd, set the roll off to 150 as there is actualy no cross over on the sub at all.

edd

[brucek]

A little confusing to look at since you changed the horizontal scaling and target between the two before and after pictures.

You didn't do anything about the peaks around 130Hz and 160Hz because this will normally be in the crossover rolled off area?

brucek

[eddthompson]

yes, i only noticed they changed after i posted them, ill fix that next time i fire up rew.

The peak at 10hz on the after was a car going pas the house.

the reciver crosses over at 80 hz (my speakers are THX specification, so pretty inflexible), when i find some longer cables ill feed the rew signal through the amp and into the bfd, then i should be able to equalise everything to a nice curve.


edd

[JohnM]

Looks like you measured with the main speakers active? If so, set the speaker type to "Full Range" rather than "Subwoofer" so you get a flat overall target (plus your house curve).

[eddthompson]

no just the subwoofer. the sub is passive and driven by one channel of an ep1500.

I connected the external soundcard directly into the input of the behringer, since there is no cross over to speak of in this chain, you could probably run all the way to several hundred hz.

when i have some longer cables, ill connect it to the reciever first, and the bfd to the recivers sub out, this will then give me a signal crossed over at 80hz.

so far its sounding very good, you cant realy tell there is a sub if you know what i mean, just better bass.

edd