Subwoofer slam vs boom

Generally speaking what causes a subwoofer to be boomy, verses crisp and "slammy"?

Does placement and room acoustics greatly affect this, or is this just a common problem with lower end subs?

Currently I am using 2 HSU VTF-3's with opposite front corner placement, with all speakers set to large. The processor supports stereo subs, kinda a moot point with all large speakers thou. The subs should be doing the least amount of work possible, i.e. I am not rolling over 7 channels into one sub.

Thanks all
I think being turned up too loud is the biggest reason for a sub sounding bad. Your subs are terrific quality, so that isn't the problem.

Move them. Try them in the same corner. Try opposite corners but moving one one of them out a little from the corner (so they're asymetrical). Turn them down a little...

They should be outstanding subs, keep trying. I doubt spending more on your sub will solve your problem. They should be plenty slammy and not boomy.
Hi Marty ... it might be corner placement. I have a REL Strata .. a very different, sub, but still a sub. It's crossed at around 30Hz with my mains. I found that corner placement sounded very very boomy, even with the gain turned right down. I now have it out in the room, quite close to my listening position, just inside the right hand speaker. Now there's no boom at all and the bass goes very deep. Now I have the gain quite well up.

Try pulling them out from the corner at least 2-3 feet into the room, just to see if some of the boom goes away. If it does you'll have to find an acceptable trade off between sound and position convenience.

I know a lot of people swear by corner placemeent, but I found that it only creates lots of boomy bass ... for quality bass the sub has to be well away from walls.
Between using the corner or not is really a setup / integration issue from my experience. Since the corner is more active, it works best from my experience to leave a gap between where the bass in the speakers ends, and where the subwoofer takes over. If the sub is not in the corner there can be some overlap of the subwoofer and the bass of the main speakers.

The boom you hear in the corner under this assumption is that fact that there is too much bass at the cut-off frequency. The subwoofer, the speakers, and the corner of the room all taken together, is producing too much bass at that frequency.

If you adjust the subwoofer well in the corner, this gap will have bass partially from the speakers and partially from the subwoofer. If integrated in this way, you won't be able to tell where the speakers end and where the subwoofer takes over (Seemless integration).
Sugarbrie ... I have to disagree from personal experience. I had the REL on very little gain, with the rolloff down at about 25Hz and it still boomed away in the corner. The only way I could get good integration, and slam without boom was to bring it into the middle of the room.
I know you also have a sub (a REL I think) so I suspect that it's something to do with my room, perhaps that it's quite small.
I thought I was cheating by using all large speakers. In hind site for a ht setup this might not be true.

What is in the .1 track? I wonder if some frequencies are not being duplicated in both the mains and subs. What I have tried to do is let each piece of equipment do its own job, and not over load one piece.

I tried the subs out in the room, still not slamming. the subs are set about +2 db over the rest. This is not too high, I hope.

Before I got deeply into this hobby, I was at a friends house, listening to his rig. I have no idea what he had for equipment, since moved away and can not ask, but he played a demo disc and WOW. Some guy coughed and it felt like someone whacked me in the chest with a 2X4.

This crisp slam is what I am after.

Thanks all

I noticed the slam in my system vastly improved when I switched to a different amp in my woofers. I used to use IRS Betas with Adcom monoblocks and they had some good bass, but then I upgraded to the IRS V, which have a 2,000 watt amp in each tower. I believe that they are digital amps. Slam galore. Since it uses the same drivers as the betas and 12 woofers vs. 8, the biggest change was the amp. When listening to a bass cascade on Without Me from Eminem's The Eminem Show, it actually felt like I was falling. And on track 3, well, there is some slam. I must put a lot of it on the amp. Of course, the speakers have to be there to be driven as well, but it isn't just the speakers or the placement.
Seantaylor....I agree it can always just be your corner compared with the rooms I have integrated. Carpeting versus hardwood floors matters also. There is no one single way that works for all, as is everything in audio. That is why I also mentioned how overlapping the roll-off has worked for me away from the corner.

No matter what the cause, if someone is using a quality sub, with too much boom, it is probably a sign of too much bass at some frequency.

Richard E. Lord (REL) from what I have read, tried to designed his subs to go in the corner as a first resort, if possible. I think many people want the sub out of site, especially in Europe.
Marty if you're after slam & dynamics without the boom; check out Tom Danley's ServoDrive ... the contrabass are killer!
The reason you have sloppy bass is probably the fact that you have so many different drivers trying to move air at low frequencies. When it comes to tight bass less is sometimes more. The less things you ask of each component, the better they can work. The first thing you should try is setting your speakers to small and allowing your subs to take over below 90hz (usually the point most preamps/av receivers are set to). You may even want to go with a single sub- the VTF-3 puts out quite a bit of bass from what i've heard. I don't know what kind of bass management capabilities your processer has but you may want to invest in outlaw audio's icbm. This will allow you to fine tune each speaker's crossover point with the subs, particularly helpful if some of your speakers produce nice bass below 90hz. Lastly, two woofers operating in phase fireing opposite each other will cancel each other out, you may want to adjust the phase of the subwoofers. Keep in mind two subs do not equal twice as much bass, the only reason you should use a second sub in a room is to account for an odd shaped room that may have some sort of acoustical imbalance (i.e. open on one end). You may even be drawing too much AC out of the wall, five speakers and two subs, plus a TV if you are watching a movie will draw a hellava lot of current. This should be easy to spot b/c your lights will flicker- turn something off!. With your equipment you should be able to loosen fillings, bowels, cement and so on, its just a matter of proper setup. Let us know how it goes-
Thanks for the help all, just pack to tinkering I reckon...

The processor has stereo sub outs, with the usual large/small speaker sizes and bass redirect and roll off. Cross points are 50,65,80,90 and so on up. The processor can be switched from one to two subs, or none.

The amp and subs share a 30amp dedicated line, with the source equipment on a 20amp dedicated line. Current "should" not be a problem, I have 200amp service to the house(renting, guess I should have asked before I installed the lines...) with an old Push-Matic circuit breaker box. New breakers for the lines.

I still am confused about the speaker settings, to me if a speaker is large, so flat to 40hz, and you set it as a large, does this speaker play stuff at 40hz, with the subs playing the same thing at 40hz? Back to what is in the .1 track.. Does this track contain the same information as in the front mains? My guess is yes, so their is no reason to have "large" speakers.

I really love the idea of the Outlaw ICBM, with the ability to tweak each speaker. I just having a hard time sticking a $250 piece of gear smack in the middle of $20k worth of electronics. The cables would all have to be unbalanced, ect. On the other hand, for $250 bucks, this is a drop in the bucket compared to the rest.

The current room does have an open corner. Stereo subs are impossible to "localize", blend in very well. Sounds silly, but it is hard to hear one sub when you have two.

opps, the subs are both in the same phase, different phases kills the bass
Hmmm i don't think you'll need an icbm, your preamp seems to have the right features. That whack in the chest feeling you are looking for occurs in the 70-80hz area. Real bass below 30 is felt in the bones more then it is heard. I'll bet your friend was using a subwoofer that didn't have as flat a responce as your subs. My first speakers were a pair of cervin vega at-12's. They could hit you in the chest like oj but really didn't put out much below 40hz. If you want a flat responce you can't have a big bump in that upper bass region. I now how have a pair of Dynaudio 1.8's which have a much better bass responce, but don't put out nearly as much slam as those old vega's. It could be that your gear is too good. You probably have a nice flat responce down to the upper teens, i bet with the right song you could crap your pants heehe. What you need to do is un-audiophile your gear a bit. Set your speakers to small, and your crossover to 80 or 90 so your subs will work that upper bass. Set the subs to max output and let it rip. Make sure there are no pets or small children nearby and then play some good old rap music or that scene fom Heat where they bust out of the bank. Those M16's should sound like a sledge. In responce to your other question, the .1 is a discrete low frequency channel movie makers use to place only low frequency information. The information on this track will only be sent to the subwoofer if one is present or 'large' in a system without a sub. When speakers are set to 'small' all information below the crossover point is redirected first to the sub, and then to any 'large' speakers. The bass management abilities of preamps and recievers varies greatly and tends to be the weakest link, but if you can choose the crossover point, you probably have a pretty good one. Having large speakers in a hometheater setup is still a good idea because all channels are full range these days (20hz-20k).
... I thought I would get kicked out of here for saying the C word(Vega's). Those were my first speakers years ago, sounds funny saying that I am 26. I still have them, the DX-9's. I tried to use these as passive subs, disconnecting the tweeters and mids, running the .1 channel straight to the subs via a Bryston 9B amp. Just did not like the result, the HSU-2 I have sounded way better. The Vegas just sounded like someone put a metal garbage can over my head and was beating on it with a rubber hammer.

I was thinking of bypassing the HSU-3's amps and running the signals through a channel on my Simaudio Titan amp(7ch). Anyone know if this idea would be worth a try? I am wondering if the Sim might have better control over the HSU drivers. No the best solution, drawing the juice out of the Sim might not be the best idea, but this thing is so dang big, I don't think it could ever run out of power.

wait a minute did you say 25k in gear? what kind of system do you have? there is noo way you can have bad bass in that neighborhood, well maybe if you lived in yellowstone. Anyway I'm 26 also, i use dynaudio contour speakers and have a harmon/kardon signature amp/preamp- don't laugh it sounds great and I can play them just about full out without a bit of strain. i don't use a sub for music and never felt the need for one. I might pick one up for home theater, but then again i've got neighbors and you know how that can be. i'm rocking dmb right now and having a keg can, what could be better? maybe that's your problem- wrong state of mind ;)
I think the room I am working in is screwing things up, alot. Next I guess I will rotate the whole mess 90 degress. See what happens.

Wrong state of mind, given. I do not use subs for music either, just with HT I want a system to grab me by the balls and wip me aroung the room. It's not that is sounds bad, I just don't know what it could sound like. I want the 2x4 whacking feeling.

I need help...:)

BOOM can be caused by room acousic problems. I have Khorns with isolated reinforced corner walls made from two inch thick very dense fiberboard. When you hit it with your closed hand, it creates a solid sounding THUD, not a BOOM.
As a result of the solid corners, the bass from these Khorns is the most realistic, undistorted bass that I have ever heard. The walls are made with two layers of drywall using insulation, sound channels, ASC isowall damp pads. The bass in the room creates a compression that crushes your chest, but once again with no BOOM. On the other hand, I resently auditioned REL subwoofers in a Tweeter soundroom. It was the worst sounding subwoofer demonstration imaginable. Not only was the subwoofer BOOMY, but everything in the room vibrated. The salesman then asked me if these are not the most musically sounding subwoofers that I ever heard. I smiled and walked out the door. Maybe REL are the most musically sounding subwoofers, but I guess I will never know. Tweeter obviously needs professional help with room acoustics.
Marty... I run two subs as well, although I probablydidn't do it the right way and just daisy chained them. I got it to sound ok, though. Before you rotate your whole room, which takes forever and might not do the trick, try just putting your subs along the walls. I mean, rotate the subs 90 degrees in the room, but leave the rest of the stuff where it is. It might help. I have one close to a corner and the other halfway down the wall. Sounds good and slams and booms at appropriate times only. Otherwise you could just mail me the HSU-2 and I'll keep it.... haha. good luck