Powered Sub Question

[David]

I should probably go over to the a/v forums, but I know there are some folks on here who know their stuff. In our remodeled kitchen, I buried four excellent flush-mounted Boston Acoustics speakers. I've run the sub wire to a custom wooden cabin that's about 30" tall, 42" wide, and 24" deep.

 

To save a little money, I used a sub I had lying around: Anthony Gallo, downward-firing.

 

It's all powered off a good Onkyo 7+1 in a 5.1 environment.

 

Anyway, the sub sounds terrible. Gallo makes great stuff, but either it's gone bad or the physical environment is bad. I was just going to replace the sub and then it dawned on me that maybe the placement itself is the problem, given that there's a largely static air mass in the cabinet.

 

I should probably just move the sub out of the cabinet, next to it, and see if that helps, but I figured I'd ask the experts. If we were talking about throttle bodies and air box dimensions and stuff, I might know what I'm talking about, but here I'm clueless.

 

So, is the sub bad and I just need to replace it?

 

Or, have I violated some rule of the universe by not letting the cabinet breath?

[Allen Rowand]

Move the sub. Low frequency is heavily affected by boundary conditions, i.e. walls. My thought is that you're getting all kinds of phase cancellation/reinforcement by having the sub inside a cabinet which is making it sound bad.

 

If I'm wrong, at least you'll know the sub is bad

 

Allen

[VinnyR11]

Did you or a carpenter build the "custom" box that the sub is in, or are you using the sub mounted in the box/cabinet as designed by Gallo? With a powered sub, placement isn't all that critical, other than some need to be a few inches from a wall; however, you can not simply stick a good bass subwoofer in a box that is not designed specifically for that speaker. It will most likely sound like garbage.

 

With bass, the cabinet is equally or more important than the speaker. At any volume, you have to move a lot of air with bass, and the boxes that sound best are very well designed. I've used great speakers in bad boxes that sound like crap, and decent-good speakers in great boxes that sound terrific.

 

If it's in Gallo's box, and it's not buzzing like a bad cone or driver, did you check your crossover setting? That's a common problem source.

 

Does the bass sound flat, rattly, boomy? What specifically is wrong. Could be anything from a shot cone or driver, bad amp, bad crossover, to a bad cabinet design. I know you've done it already, but triple check the connections and setting on your Onkyo. If the all the mechanicals and set-up check out, I'm betting it's the custom cab.

[David]

Thanks, guys. It's a custom build cabinet:

 

 

The sub is in the OEM enclosure (round, bottom shelf, toward the back left):

 

 

Here are the flush-mount ceiling speakers:

 

 

After reading your replies, I'm thinking that two things are bad. The sub probably is (yes, crossover setting is good). But the placement, too.

 

I think I'll put the sub from my office setup (Mirage, Omni S-10) in the kitchen, just to the outside of the cabinet, and see how it sounds. It should sound terrific with those wood floors.

 

Then, maybe I can find a $200-300 side-firing sub and cut a hole in the side of the cabinet and cover it with black material so that it's not terribly noticeable.

 

That sound like a plan?

[Lone_RT_rider]

Man David, with your constant quest to conquer new and exciting things....I was kind of hoping this thread was about this .....

 

 

 

[David]

Me too. That sounds like a lot more fun!

 

Remember putting Alka-Seltzer in discarded 35mm plastic film containers, using a needle to make a hole, and then using it as a submarine in the bathtub?

[Lone_RT_rider]

I remember those, but we had the K-mart supplied versions similar to these....

[Jake]

I think I'll put the sub from my office setup (Mirage, Omni S-10) in the kitchen, just to the outside of the cabinet, and see how it sounds. It should sound terrific with those wood floors.

 

Then, maybe I can find a $200-300 side-firing sub and cut a hole in the side of the cabinet and cover it with black material so that it's not terribly noticeable.

 

That sound like a plan?

 

With your remodel, I'm having a hard time visualizing where that is. Definitely relocate the sub outside the cabinet. You don't want it touching anything that vibrates (are those Riedel wine glasses?!?). If aesthetically tolerable, place the sub in a corner of the room, nearest where you will be sitting, then tweak the placement from there using your favorite listening material (I recommend Psycho Killer from Stop Making Sense). Also, run your SPL calibration thingy to optimize the EQ. If no good, try hooking up a second sub just for a test to see if you need two. I'm guessing your remodel has created a fairly wide open space, difficult for subwoofers.

 

Do not cut a hole in that cabinet to place a sub in there - there's no undo button on that deal! Also, your sub might be ported, so all you will create is a muddy, rattling mess. Cabinets hold wine glasses, not subs. Yes, I can hear Julie from here regarding the SO acceptance factor on all of this.

 

You can always go for an in-floor or in-wall mounted sealed sub. Velodyne and Paradigm make 'em, along with others I suppose.

[David]

Jake, in the remodel we took out that long weight-bearing wall. The combined room is now 18x26' (9' ceilings). You can see the black cabinet between the two bay windows, about two-thirds of the way across the picture, in line with the hanging light that is turned on. You can see one of the four ceiling speakers on the right. BTW, there's no way I'm running new wire.

 

 

And yes, Julie said to tell you that "she agrees with Jake about cutting the cabinet."

 

[i know this is a crappy picture, but the iPhone can be turned into a cool panorama tool with a piece of software called Pano from the iTunes store.]

[VinnyR11]

Thanks, guys. It's a custom build cabinet:

 

 

The sub is in the OEM enclosure (round, bottom shelf, toward the back left):

 

 

Looking at your photo, one thing comes to mind.

 

Don't do that.

 

Moving the sub out of the cabinet is mandatory. Sounds like you're heading in the right direction. Do not cut any holes in the cab. It's not made for a sub and the sub shouldn't be there.

 

I disagree that you'll need to add a second sub. The room isn't that big, and sub frequencies carry much better than highs. That's why you usually hear way too much bass when you're standing outside of a club. Just tailor the sound of your sub so that it's neutral throughout the room.

 

With subs, less is often more. The primary bass frequencies should be coming through your primary front speakers. The sub only adds the deep bottom coloration, and instruments will sound more natural with a properly adjusted sub. Many people use way too much sub for true sound reproduction, so start out with lower settings.

 

 

[vizhip]

+1

 

Regards -

-Bob

[Jake]

The room looks beautiful! Nicely done.

 

Given the dimensions, you have 4,212 cubic feet of space - that's about twice the area for a typical listening room for which most subwoofers are designed. Therefore, a two subwoofer solution may be optimal, particularly as your general sitting area is in the middle of the room. Bass frequencies are typically more prominent along the walls. I know this is not your primary listening room therefore two subs are unlikely, but you are up against a challenge with all that space.

 

To clarify, subwoofer frequencies do not carry easier than highs. They are, however, less directional which is why placement is not as critical for proper imaging & soundstage. One's ears can easily discern when and from where a high frequency tone reaches them, less so with low frequencies. Also, a subwoofer is a very inefficient means to making sound, which is why most of them are powered with substantial dedicated amplifiers. What one hears when standing outside a nightclub is the sound pressure escaping the room - as the club is in effect one big speaker enclosure. You hear mostly bass because the tweeters and mids aren't pointed at you. Go into the club (closer to the speakers), and the boomy bass tightens up and becomes music.

 

I'd try placement right under the center bay window by the table (sorry Julie!). With your particular sub, you can keep the amp part in the cabinet, and just move the speaker enclosure, minimizing the wires. Stick a plant on it for looks!

[VinnyR11]

The room looks beautiful! Nicely done.

 

Given the dimensions, you have 4,212 cubic feet of space - that's about twice the area for a typical listening room for which most subwoofers are designed. Therefore, a two subwoofer solution may be optimal, particularly as your general sitting area is in the middle of the room. Bass frequencies are typically more prominent along the walls. I know this is not your primary listening room therefore two subs are unlikely, but you are up against a challenge with all that space.

 

To clarify, subwoofer frequencies do not carry easier than highs. They are, however, less directional which is why placement is not as critical for proper imaging & soundstage. One's ears can easily discern when and from where a high frequency tone reaches them, less so with low frequencies. Also, a subwoofer is a very inefficient means to making sound, which is why most of them are powered with substantial dedicated amplifiers. What one hears when standing outside a nightclub is the sound pressure escaping the room - as the club is in effect one big speaker enclosure. You hear mostly bass because the tweeters and mids aren't pointed at you. Go into the club (closer to the speakers), and the boomy bass tightens up and becomes music.

 

I'd try placement right under the center bay window by the table (sorry Julie!). With your particular sub, you can keep the amp part in the cabinet, and just move the speaker enclosure, minimizing the wires. Stick a plant on it for looks!

 

 

Good points, although I'd still suggest 2 subs are one too many for room with this system. Without a very different speaker set-up, in this room, one sub should be plenty, but that's why you get 10 techs to set up a system and you'll get 10 different systems. And the only one that's right is the one you like listening too the most.

 

You're 100% right about the bass sound travel, it's primarily diffraction that cause the lower bass to sound (or appear) louder vs. the highs, but I'd suggest that the effect is usually the same. I could have been more specific, but I was trying to use layman's terms to get across the effect. There is almost always something in the way, so the effect is the same.

 

When you stand on stage or next to a stage inside a large club with people (or stuff) in it and then walk away, the bass "carries" more. It is very noticeable. In most any room, there is always something in the way of the sound, and the bass comes through more the further from the stage you are.

 

I also understand your point about directionality outside a club; however, point all the speakers at a far wall, stand outside that wall and the bass comes through the most. It is probably for a host of reasons, (perhaps it sets up oscillation in the material better?) but the effect is there.

 

Just a point about low frequencies...

"Diffraction of sound waves is commonly observed; we notice sound diffracting around corners or through door openings, allowing us to hear others who are speaking to us from adjacent rooms. Many forest-dwelling birds take advantage of the diffractive ability of long-wavelength sound waves. Owls for instance are able to communicate across long distances due to the fact that their long-wavelength hoots are able to diffract around forest trees and carry farther than the short-wavelength tweets of song birds. Low-pitched (long wavelength) sounds always carry further than high pitched (short wavelength) sounds"

 

 

[Ken H.]

Me too. That sounds like a lot more fun!

 

Remember putting Alka-Seltzer in discarded 35mm plastic film containers, using a needle to make a hole, and then using it as a submarine in the bathtub?

Talk about hijacking your own thread!

 

ISFA the sound system - 7.1 baby, 7.1!

[David]

Yes, this receiver is a 7.1 receiver, but I only wanted four speakers in the ceiling.

[David]

Well, an update is in order. It turns out that several things were wrong, which explains why the process took me 1.5 hours.

 

1) Sub in the cabinet was definitely a problem. It now no longer sounds like a $1,200 Civic with a $4,000 audio system in it. I was relieved to know that the sub is actually not bad, but is in fact terrific. Good, because I didn't want to get another one.

 

2) Rewiring to treat each pair as the front A/B ended up much better than treating one pair as the surround set.

 

3) The audio for the four speakers in the ceiling needed to be calibrated further to boost the treble.

 

It now sounds like a concert hall. Thanks, folks!