Good sound without bothering neighbours?

I'm looking into some kind of hi-fi / home cinema system that can play films and music without our irritating neighbours complaining. I'm currently using standmount speakers either side of the TV in a room corner that adjoins the party wall.

Thinking of possibly a 2.1 system where the sub is located in a room corner away from the party wall and then floorstander or standmount speakers deal with ~100Hz upwards. Am wondering about the viability of open baffle speakers close to the rear wall - maybe some kind hybrid open baffle / transmission line design which damps the midrange off the back of the driver but allows the bass through to cancel out lows behind the box.

Any thoughts inside or outside the box appreciated!

Alex
 

gtforme00

Member
2004-10-21 4:35 am
When faced with this problem in my dorm-dwelling days at college, I used open baffle speakers on my desktop. They ran full range (extremis for woofers) and I had a subwoofer that I turned on during non-quiet hours. These were only about 16" from the rear wall and they sounded good to me, but I was listening in the nearfield. I was good friends with my roommates and they helped me judge the effectiveness of my experiments. The dipole configuration definitely coupled less into adjacent rooms than the monopole configuration which preceded it.

My observation (from hearing other neighbor's noise) is that bass frequencies are the most obtrusive. This is particularly true for frequencies which are room mode or system tuning resonant. I always knew what type of alignment and tuning frequency each neighbor had by the resonance of their bass. Most had the cheap computer surround systems with a huge hump at a too high resonance frequency.

My hypothesis is that dipole bass is preferable in communal dwellings, because of the minimal excitation of room modes. Following that, a monopole configuration with low qtc is the next preferred alignment.

I wonder if a dipole subwoofer would work for you? You could easily reuse the drivers for a monopole if it didn't work out. Something like the XLS 10 you mentioned (2 of them) in a phoenix like configuration: http://www.linkwitzlab.com/builtown.htm (on the side wall away from your neighbors).

Regards,
David
 
I use dipole subwoofer in basement, and bass is still very well heard on the floor above. I think room walls amplify bass even if you are using dipoles. But still, it doesn't shake house as sealed subwoofer.
I'd suggest nearfield dipole sub, maybe placed on one side of couch or behind it, with woofer at ear level (it can be masked as funiture and you can let your wife design it :) ) With this setup you'll need a receiver with time delay adjustment.
 
Is it conceivable that some genius will eventually engineer a version of noise cancellation device/circuit for this? I remember daydreaming about just such a thing one summer in college when they were jackhammering a parking structure across the street from my apartment. They'd get started at about 7:30 am. Problem was that my bar/restaurant job wrapped around 2:30 am every night. I tried to get out of my lease. No go.

I recall laying in bed desperately imagining some small diesel powered rig on a small trailer kind of like those mobile compressers they rent. It would have disco sized transducers arrayed and would manage to basically absorb any noise created within a 40 foot perimeter of it and null it for any distance beyond that.

Someone here needs to develop this into a small amplifier sized chassis as a system component. A simple knob on the front to cancel sound propagation beyond an adjustable range. Patent it, win praise, and retire to some tropical island so that I'll have just one more thing to regret bitterly for the rest of my life.


Actually, even a rudimentary overview of this ..
http://en.wikipedia.org/wiki/Active_noise_control
..suggests that this will remain a dream for quite a while.
But anything's possible, eh?
 
Seal up any holes.
Electrical outlets in the wall, etc.
Block the hole as best you can.
Glue on sheetrock if possible, 1' x 1' or so. 3/4" thick.

It'll have to be totally fixed when you move out, but it's worth it if you can.
Even doubling up on sheetrock for the entire wall if you can.
2 or 3 layers, even better.
Mass stops sound. It even reduces bass.
 

BHTX

Member
2006-02-16 10:49 am
jacco vermeulen said:

Well there goes that idea. I've had thoughts in the back of my mind in regards to inventing devices for this since I was a teenager in junior high. Never did anything with them though, and obviously never would have. Oh well.

Anyway.. I can also attest to the effectiveness of open baffle loudspeakers. All I've tried is 2 pairs of cheapo Pyle PPA 15 woofers in a very resonant W-U type baffle that just wasn't right. However, when EQ to hell, it was ok, although it still excited room modes much more than I would have liked. But even then, there was a drastic change in the way the sound propagated through this place. Rather than being overwhelmed with sub 40Hz resonances in my bathroom, as is the case with monopole subwoofers.. I could hear things rattling in other rooms long before getting much of a resonant effect back there. Of course, anything directly behind or in front of the speakers (consider the space on the other side of your walls too) will be the loudest. But even then, with room modes being less existent, it seems to be much less severe in other rooms (but also less impact at the listening position..characteristic of dipole bass). In my small amount of experience with them, even standing up from the listening position resulted in a dramatic decrease in low frequency information, due to the cancellation above the baffle. It's far from 100% effective for neighbors, as they'll still hear it..especially when listening at higher levels. But I think from their perspective, it might be somewhat similar to significantly decreasing those bottom octaves with an EQ.. yet from your position, there's nothing really missing, especially once you're accustomed to the sound of dipole bass.

Thing with me is.. I don't particularly care for the negative effects of monopole designs in the low frequencies, yet it's what I'm accustomed to. I definitely think it'd take some getting used to dipole bass.
 
Presumably if I replace the bass output from the speakers (by highpassing them @ ~100Hz) with output from a subwoofer in the opposite room corner, thus shifting the bass source from 0.5m to 4m from the party wall the sound that gets through the wall will diminish by 18dB assuming identical frequency response?

Now obviously the response will be different, hopefully extending flatter and lower - I'm guessing lower frequencies will be more prone to going through walls, but with fletcher-munson on our side and presumably the average human more attuned to being annoying by 80Hz boom from party speakers, the situation might be improved further?

If I have the sub ~3m from the mains can I crossover at ~100Hz and have a coherent sound? For home cinema am likely to be sitting very close to the sub but for music am more likely to be equidistant from sub and mains, 3-8m down the room.

Alex
 
BHTX said:

Such devices are standard in submarines and merchant marine vessels, in particular cruise ships.
In the sound/vibration classes i had, the vibe prof. talked about the R&D of active anti-sound gear, the small commercial headgear items which have been available for years now.
At the time i had the same thought how cool it would be to be able to electronically optimise the acoustics of a room, dream on.
 
I don't think re-positioning the sub will make a lot of difference. Bass doesn't attenuate over distance as much as high frequencies.

This prob wouldn't work for music, but would be okay for HT I think. HP main speakers at 80-100Hz and use one of these on your chair for the bass - http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=299-028

Or get headphones for late night music and movies!
 

BHTX

Member
2006-02-16 10:49 am
Forget messing with the position of your subwoofer. It shouldn't help much, if any at all. In fact, I've had more than one experience where positioning a subwoofer in a corner on a wall of an adjacent room yielded less bass in that adjacent room than when it was farther away from it, which is definitely understandable.

And, IMO, don't waste your time with attempting to control this problem passively (adding mass to your walls, etc). I made this mistake in my last apartment. Didn't do me a damn bit of good. Only a major hassle when it was time to leave. And after all the time I spent redoing things before I left, I was still charged fees for it.

If you, like many people (myself included), refuse to resort to headphones (they have plenty of their own compromises, as does everything), then my suggestion is this..

1. Dipole loudspeakers. If at all possible, re-arrange your room so that the location of the main problem areas are more to the sides, top, or bottom of the speakers. As with most dipoles, you don't want them too close to a wall, and in this case, I think it'd help even more to have them farther away from any walls or large flat surfaces (except for maybe the floor, of course). If re-arranging your room isn't possible, this might all be hopeless, as I don't think dipoles will help a great deal if the annoyed neighbors are directly on the other side of the wall right behind them. If it's one main wall that's being shared, the speakers need to be perpendicular to it.

2. If you're used to your brain being rattled with sub 40 Hz bass notes, forget all about it and pretend it doesn't exist. Get yourself a ButtKicker LFE or two. I have a pair, but they're still collecting dust since I need a new couch anyway. Expect usable bass extension to 35-40 Hz at the very most and leave it at that.

3. A simple pic of your room would be great. If it's just one photo, either take it from the listening position, or try to get the entire room in the photo. If you feel funny doing that, put it on a free image hosting server for the time being, then remove it whenever you want once this thread has settled down.

4. People will offer you their thoughts/recommendations/opinions in regards to what you should do, how you should do it, and what things you should get to do it that way.

5. Do what was decided during step #4, and keep going until it's completed, taking interesting photos every now and then throughout the process so we can all come here and stare at them when we're bored.

6. If all goes well, you end up very satisfied with everything you've done and it works out ok with your neighbors at very reasonable listening levels.

7. You take even more pics of your completed work so we can all stare at it and tell you how good you did, etc.

:)
 

BHTX

Member
2006-02-16 10:49 am
Simplest affordable solution?

I'm just gonna throw this out there and see where it lands..

I haven't seen your room and don't know it's size or characteristics or anything, so this little thought might actually suck for you. Anyway, if you've ever heard a pair of planar speakers and liked them (particularly Magnepans), don't have a problem with EXTREMELY narrow dispersion of high frequencies, don't have a problem with surfaces much too large to be reproducing 16KHz+ attempting to reproduce it, phasey stuff in the higher frequencies doesn't bug the hell out of you, or if you've heard any single driver full-range loudspeakers that you liked..

..Magnepan MMG-W's are $300/pr new last time I checked, ordered directly from them, of course. Design and build a pair of simple U, H, or W frames or something of that sort (with just the right woofers!) being careful not to make them stand too tall, then mount the MMG-W's to it. Add the matching center channel speaker from them if you like (I think it might be the same price?). Place your seating position and speakers perpendicular to those neighbors, and keep your new speakers far enough away from any walls.

I have a pair of these sitting in the closet. I originally bought them to use as rear channels in a system that I now want to sell. I'll probably end up keeping these MMG-W's though.. just to play around with. I finally got around to hooking them up to an Adcom 555 MKII that I have laying around just for those kinds of purposes, simply leaned them against the very edges of my 67" DLP.. they stayed there for months. I just put them back away recently. I'm sure they would have sounded MUCH better lifted up at least a foot or more off the floor. Anyway, it sounded really good sometimes at low to moderate volume levels... as long as I didn't move my head a single inch. After a while, I started thinking of how silly it was to sit with my head in a vice.. might as well just get a good pair of headphones for the same price, could at least move my head with those. Anyway, on top of the simplicity and ease and all that.. I can't think of a better type of loudspeaker to keep mid to high frequencies focused in one location.. except for maybe horns.

Just a thought.
 

CLS

Member
2005-06-17 6:58 am
Taiwan
Normally, the mid-high frequencies penetrate through boundaries less than bass. Through closed windows and doors, neighbors usually hear muffled booms and thumps, which is annoying. Like what we hear at the doorways just outside of the theator.

I found OB bass produces far less energy off axis and conveys much less to next rooms. It does not pressurize the room. So OB systems are widely described as very naturally sounding at next rooms.

So, OB systems can be more friendly to neighbors with their relatively flat-spreading spectrum to the environment. The evenly attenuated sounds to neighberhood are much less intrusive.

Furthur, the clean trancients and excellent dynamics from OB systems can deliver very satisfying overall sound with less SPL.

And OBs are easy to build! Strongly recommend!