Equalizer help speaker boom?

[cool9]

If experimenting with room placement doesn't reduce speaker boom can you use an equalizer to manipulate the bass to reduce the boom? There are only so many places you can put speakers in a room and they can only be so close to you.

(This thread discusses room nodes and resonances and the option of using a sub and equalizer.)
http://forum.ecoustics.com/bbs/messages/1/198679.html

I have Infinity Kappa 8.1 and are pretty boomy. Room is 13'x15' with high ceiling (15' at highest).

 

[michaelhigh]

Does it happen all the time or when you use your turntable only? If it's your TT then padding under it or better isolation should solve your problem. If it's another problem, placement is a good solution. If space limits your options, work within the limits and try to get some further advice. This is the best I can suggest. Good luck.

 

[cool9]

I've only had Kappa 8.1 (89 dB, 6 ohms) for a week. My Kappa 7 (88 dB, 4-6 ohms) are sealed and do not boom. Can bass woofer distortion (due to lack of power maybe) cause boomy bass? At first I stuffed the ports and it sound much better but I read that that's a bad idea because you're messing with the overall design of the drivers (damping, sensitivity, etc.) and could cause damage.

 

[Copa1934]

I wouldn't rule out the vaulted ceiling. Is there acoustic insulation on the ceiling or is it just paint/bare surface?

Damage? Maybe if you overdrive them, but I kind of doubt it. Stuffing the ports is not uncommon for many types of ported designs, but I haven't read anything about damage due to stuffing. You will change the characteristics, but if you like the results, who's to argue? They are your ears after all.

 

[cool9]

I read a thread at Audiogon where someone who stuffed the ports blew his drivers. The ceiling is regular wallboard and a triangular roof. I've used other speakers (Polk, JBL, B&W) in the room without this problem. These 8.1s are very tall (48") and have large ports. It only makes sense that stopping the airflow in the cabinet will interfere with movement of the drivers.
The bass woofer inside is completely surrounded by pieces of foam and I was told that low frequencies can go through the foam and vice versa for high frequencies. Maybe I'll lightly fill the port so some of the air can move in and out.

 

[goanlisten]

Assuming placement (which others have suggested) does not help with the boomy sound I have a few suggestions:

Ported Systems depend on air inside the box cavity as well as the spring suspension of the driver to alter the sounds and make that more pleasing to the ears (In plain simple terms). Stuffing the air cavity with foam and or other stuffing will change a woofer's frequency characteristics and thus the sound.

I'm wondering if the previous owner added foam (since your message implied you found foam) inside in an attempt to improve the sound and perhaps left it there. I would remove all the foam stuffing and see how that affects the sound. Then gradually adding a little at a time until you tune it to your taste. Also it is a good idea to tack the stuffing to the inside walls of the box, rather than place the stuffing on the bottom, which might block the air path.

Good luck to you!

 

[RichPA]

To answer the original question - yes, an EQ can help a lot, but octave-band is usually not fine enough control. You really need parametric, or at least third-octave, control for this purpose. Also, it's important to be able to adjust the two channels separately.

 

[Naptown Rob]

To answer the original question - yes, an EQ can help a lot, but octave-band is usually not fine enough control. You really need parametric, or at least third-octave, control for this purpose. Also, it's important to be able to adjust the two channels separately.

I agree.

The fact that your room is close to a cube probably isn't helping things - although that vaulted ceiling should mitigate the effects a bit. If you haven't been able to get the results you want through placement alone, there's no harm in trying a tool.
Try playing around with things in the 150 - 200 Hz neighborhood.

 

[lensman]

The booming bass you're hearing is most likely because the room boundaries and your speakers' low frequency waves are interacting to create at least one major frequency peak, if not more. Because you now have a set of ported speakers, you're dealing with two sets of low frequency resonances reacting with the room and you may also be contending with additional frequency waves below what your previous speakers could produce. I'd bet your speakers are fine.

As others have suggested, moving your speakers should come first. I've noticed moving speakers even a few inches can help. Next, you can decouple your speakers from the floor using spikes or rubber feet. This may help by reducing resonances through the floor. If those things don't work, you could try to detune your ports by making tubes of foam (perhaps 10mm thick or so) and inserting them into the ports. If this is what you did and it worked, your speakers will be fine. I wouldn't completely block the ports.

If you happen to have a graphic equalizer floating around, you can try it. But be aware that it may create new problems and not adequately fix your current one. Just as you have low frequencies that are being reinforced by your room to create the booming, you're also very likely getting dips in your bass at other frequencies as the room/wave interactions create cancellations.

A graphic EQ might help you attenuate the peak(s). But because graphic EQs have fixed frequencies they adjust, you may not be able to squarely hit the points where your bass is booming the worst. Graphic EQs also have fixed bandwith ranges around the center of the frequencies they adjust. So they can often end up attenuating both the the peaks and nearby dips in bass, creating noticeable voids.

As others have stated, Parametric EQs are the preferred solution. These allow you to set the both the center frequencies and the bandwidth range to be adjusted. This means you can much more precisely target the frequencies you need and choose bandwidths that allow you to even out your sub's bass without attenuating frequencies where the sub is weak. Here's a basic overview of what can be accomplished with a Behringer Feedback Destroyer (the most popular parametric EQ) with links to explore more: http://bfdguide.ws/