First real measurement subs, subs+main, subs+main large

i took several measurements... one for each crossover point 80,100,120, with the subs alone and with the subs+main... then i also did it with the subs+main and the l/r speakers set to large... so i was just wondering what u think of and make of my results... here are the first results of the sub by itself 80 then 100 then 120...

here is the subs and mains together with the mains set to small for 80, 100, 120...

here are the last three... with sub+main and mains set to large for 80, 100, 120...

[brucek]

I'd probably leave the crossover at 80Hz. There isn't too much difference in the response with the three crossovers and 80Hz will be the least localizable.

Your response is quite good. You could use some equalization for the peak centered around 55Hz. It would help to reduce it. Do you have a BFD?

brucek

i haven't bought one yet... i wanted to measure first to see what i had before i decided to buy one... what kind of noticable difference does equalizing ur sub make???

also when i measure the sub and main(small) together why is there that huge drop down at 80hz??? should i keep my speakers set to small?

aslo if i were to get the dsp1124 is there any good place to get one now that they are not produced anymore???

[brucek]

what kind of noticable difference does equalizing ur sub make???

Usually, when there is a hump in the 40-70Hz area it is quite overpowering and ends up sounding like what they call 'one note bass'. Think of those cars that go by and you hear that boom, boom, boom...yuk. It's quite a difference if you flatten out that low end below 80Hz.

why is there that huge drop down at 80hz???

This is a standard interaction around the crossover between the mains and sub and is usually corrected by adjusting the phase of the sub. It's nice if your sub has a variable control, but if not, use the 0/180 switch.

dsp1124 is there any good place to get one now

You can check the internet on-line stores. Most cities have music shops where they cater to bands and concerts etc., and they usually have a behringer contract. Check in the phone book for a music shop.....

brucek

thanks for all the help... i have a nht 12 sub which has a boundary eq and a phase 0/180 switch... when i get a eq and do measurments again i will try messing with those switches...

[Wayne A. Pflughaupt]

Is it located in a corner, or somewhere else?

Regards,
Wayne

[lovingdvd]

brucek wrote:

Usually, when there is a hump in the 40-70Hz area it is quite overpowering and ends up sounding like what they call 'one note bass'. Think of those cars that go by and you hear that boom, boom, boom...yuk. It's quite a difference if you flatten out that low end below 80Hz.

Yep. So much so that its what drove me to REW/BDF in the first place.

I knew nothing about bass equalization or even the need for it, until I got my sub and noticed it sounded way overbearing and muddy in deep bass scenes. Turns out that I had a nasty +15dB or so peak in the 40hz range and I'm using REW and BFD now specifically to tame this.

[Doug Plumb]

The critical band is between 100 Hz and 5 Khz. Below 100 Hz is not very important and even high Q room resonances tend not to be audible. The measurements above 100 Hz should have high Q resonances damped out or notched out.

The best way to handle room LF's is to use more than one sub, experiment with placement and phase settings.

If you can put 3 subs in its unlikely you can experiment with placement much but you can exoeriment with phase settings.

If you can take 8 shots then do this.

(1) sub1 = 0 deg sub 2 = 0 deg sub 3 = 0 deg

(2) sub1 = 0 deg sub 2 = 0 deg sub 3 = 180 deg

(3) sub1 = 0 deg sub 2 = 180 deg sub 3 = 0 deg

(4) sub1 = 0 deg sub 2 = 180 deg sub 3 = 180 deg

(5) sub1 = 180 deg sub 2 = 0 deg sub 3 = 0 deg

(6) sub1 = 180 deg sub 2 = 0 deg sub 3 = 180 deg

(7) sub1 = 180 deg sub 2 = 180 deg sub 3 = 0 deg

180 deg = reversing connections.

See which one gives you the best response.

[Doug Plumb]

Adding some absorbers like the RealTrap ones can help in the bass too.

[Doug Plumb]

Of course real sharp resonances may need to be tamed but using many subs can fix this too

[brucek]

The critical band is between 100 Hz and 5 Khz. Below 100 Hz is not very important

Yeah, anything below 100Hz doesn't respond to room treatments or traps very well unless you involve very large physical devices. At the lower frequencies (where subwoofers play the biggest role) the wavelengths involved compared to standard room dimensions are large enough that the behaviour is considered minimum phase.

This means that primary reflections (second order) from the walls, ceiling and floor arrive at the listening position anywhere in the room with a phase shift of quite a bit less than a cycle. For example a 40Hz signal has a wavelength of ~28 feet. The limit here of about 100Hz with a wavelength of ~11 feet is reasonable for equalization..... It's important in home theater to remove the peaks caused at model frequencies to avoid low bass boominess. Multiple subs is a lofty goal that has benefits, but difficult to put into practice for most people (cost, WAF, technical ability, etc). The modal response at the listening position is easily and effectively controlled by second order filters (same Q, inverse gain) designed by REW software and implemented by a BFD parametric equalizer.

brucek