Has anyone tried these things? I've got an l-shaped room and a 50hz standing wave that only occurs in one corner as follows: Code: +------------------------+ | X X A| | | | | | | | o | | +---------------+ | | | | X = spkrs, A = damn corner o = me | | +--------+ The sound from the left speaker is not affected by the corner (A), but the right speaker is. The only position I can get that does not cause this mode is if i move the speakers out till they are 1/3 in room and I sit 1/3 from the wall.. which is not practical for marital harmony! Are any of these products likely to help?
here's my 2p worth, Consider firing the speakers down thelengthof the room, at 90degrees to your current position. I realise that this may be difficult but you show now obstructions on the sketch. If this is not posible, you could try the following. Make ceratain there is at least 18" behind the speaker and the same from the corner. I would considermoving the whole system three feet to the left getting the speaker out the corner. If this is impractical, you need to remove the wall boundary reflections that occur in the room corner [you know this !] To do it is more difficult. Next time you decorate add a layer of sound absorbant material to the wall, like the thin wall insulation you can get that goes under the wall paper. Next try and put some heavy drapes across the end of the room . Specifically in the problem corner, allow enough room behind them to be able to site a bass trap. I saw the ideal thin in Ikea on my last viisit. You can get a bolster cushion thatabout 25cm in diameter and one meter in length, you could stack two off these on end then secure them to the wall in the corner. For domestic harmony you would need to do the other corner too. Alter the position of the Hifi so that the speakers are each side the corner firing into the room at 45 degrees. Last resorts, move to a more ideal location, or alter the room shape.I know easier said than done.
It's a common problem. I have ended up sitting 1/3rd into the room. The speakers are not too far from the wall. I filled the space behind the sofa by installing bookcases.
That would mean not being able to walk out of the house . There's a full length sliding door across that whole right hand wall. Opening the door cures the problem immediately mind you, but next door will kill me. Speakers are 40cm out (16"), and already 1m (> 3') out from the right hand corner. FWIW, a guy from ASC is coming out to "measure & quote". I'm planning on putting a bass trap on the errant corners and maybe some other panels on the first reflection point.
It's a very common problem, although I think the sliding door makes it harder than usual to cure. 50hz is a very low frequency and its just not going to work using curtains or some soft partial board under the wallpaper. To absorb a 50hz wave you would need a material with a depth of around 4.8feet. So that's not very practical. This is the principal that tube traps work on so you could do it, but the diameter of the tube would need to be around 4.8feet to work well. 2.4feet could work, but its going to be less efficient. My suggestion would be a membrane panel trap (as always!). You can make them with a thick MDF panel on the back if you don't want to mess up the wall. Then you can just hang it or lean it or whatever. If your room looks like this.... then this would be my suggestion. Sorry for the big pic I got carried away drawing it Blue prints for construction, you want to be looking at the 'Deep Bass Trap' The depth determines the frequency absorbed - Trap Plans - Deep Bass Trap Note that the one I suggest is 5" deep not 4" like in the plans. Other than that you could try EQ. The main problem with this would be that the EQ is only ever right at one place in the room. If you move about it will be completely wrong. It might be worth a go though, before you go and start DIY'ing. Check out the Behringer DEQ2496 That should give you some food for thought
yogus, if you do resort to going down the eq route, IIRC, the deq has both a digi coax in/out, which would allow you to hook a dac to its output. In theory, as all the eq is done in the digital domain, and u use your own dac, there shouldn't be too much of a compromise on sound? Some folks have bunged one of these deqs in just to experience a greater control of the sound. You could argue that if room acoustics plays a really significant part in what anyones system ultimately sounds like, then eq has a role Of course, audiophiles will be falling out their comfy armchairs at the mere thought Though, the deq wouldn't be that great for a TT as u would have to resort to using its own internal dac. Also, you'd be adding a couple of extra boxes if u don't use a dac already. Weigh this up against living with a bass trap in your living room... Might be worth checking out http://www.diyaudio.com/ as there are a few happy users of the deq I believe hth ps. tenson, nice artwork!
Yes Sanj is right, the DEQ can be used purely in digital mode so that you take the digital output from your CD player, go through the DEQ and then onto your nice DAC. It can also be used as the DAC itself. As well, it can take an analog input by sampling it, processing and then re-constructing it to an analog signal. This is a review of the old version - DEQ8024 Review It is basically the same but the new one has slightly more features and uses a better DAC. In my experience using it in analog mode.. it works as long as you only use it to EQ frequency's below 100hz, however it does add a graininess and takes away some of the detail with its only 'very good' DAC's. In pure digital pass through mode I bet it would add nothing to the sound apart from the EQ. Bass traps are still better. They also solve time delay problems that cause smearing.
If you'd put a little more info in the post originaly I could have save a lot of effert............ thanks !! Big no no puting speakers up against glass especially for there first reflection. I'd try and use ther other end of the room if posible.
Can you put the speakers into the middle of that wall well away from the glass door but before you reach the 'L'?
All Thanks for the help. I'm probably going to go down the bass trap route, either ASC or a home-made job. I'm not a good DIY'er, but I know a dude who builds membrane traps. (Problem his, he will kill me, b/c I bought my speakers from some other shop rather than him!! ) Spoke to a guy at ASC and he reckons a full round trap with built in helmholtz resonator would do the trick. About 500AUD (200 GBP) in a choice of colours . Either that or a flat panel trap in the corner. Zanash: sorry not providing all the info, and thanks for the help. I'll probably have to use an absorbtion panel of some kind to cure the early reflection on the side. Alternatively, I can always put some piece of furniture in front of the glass. It's difficult to reorient the speakers anywhere else, and I know the smearing/combfiltering from the glass will have to be fixed at some stage. Alex S: the room is a combined lounge/living, so I have to live with using that corner, otherwise I'd be listening from part of the kitchen . I might look into deq, but I would need space to put it (i've run out of shelf space!). TBH, ever since I got my new spkrs, (PMC FB1), the situation has improved a lot more than when I had mission 782s. My wife doesn't know what I'm complaining about!! FWIW,here's piccy of the room. Tenson has got it very close to accurate, although he's added an extra driver.. (PMC OB1?).
Yogus, I don't have your particular problem since I inhabit a large concrete box but I've invested quite a bit in RPG traps, absorbers and diffusors all to great effect. You could ring Acoustic GRG on 01303 230 962 and have a chat with Brian Moule. They also deal with a very helpful Acoustician called Jay whose number I don't have to hand. RPG products are not cheap but they work! I know people want to spend money on boxes but from my experience I'm sure that a good 1K amp with 1K acoustic treatment would produce a far better sound than a good 2K amp, for example. Nonetheless, its not easy to convince the rest of the family; sadly, bass traps that really work tend to be unsightly beasts. Also, and hopefully without being offensive, a look at your system says to me 'potential bass problems'. Alex
Hah... I live in Oz, so that won't help too much!! :MILD: None taken, but you'd be surprised. The room is bigger than average, with 4m ceilings, and about 7.5m X 3.8m. Its the 3.8m length coinciding with 4m that probably gives the 50Hz mode. The floorboards don't help either. It's only noticeable with the odd recording here and there. But it's always at the back of my mind!!! The bigger PMCs actually load the room far, far, far more evenly than my Mission 782s, which don't go anywhere near as deep, and the former times much better too. The TLs rolloff very slowly in the LF region, so theoretically they tend to excite room modes less. I would almost describe its LF presentation as a bit lean at times, since the 782s could be a bit plummy in its mid->upper bass.
Hi You floorboards are really looking great, I can see why you like them. I also have wooden floors, and they are to good music reproduction what Busted are to rock music. My suggestion would be take the wife shopping for a very large rug. It looks great over a wooden floor, and will help the sound no end if its big enough. You can put extra layers underneath the rug - I use sound absorbant compressed paper available from B&Q. I also use bass traps as described above, but would suggest getting two, not just the one. I would also look at alternative speaker positionings like... 1) moving the speakers further into the central part of the room and away from the corner 2) as below (left hand corner of room) __________________________ i . . . . . x i i i i i x . . . . you i Dont know if you've tried those already?
The rug is on my wife's plans for decorating. We've got a dodgy old rug, and it actually improves the sound quite a bit, but more so with the midrange (reduce echo flutter) and tames down the treble quite a bit. bottleneck: is that a mistake, or am i sitting right next to the left speaker? BTW, the left hand side of the room is actually the entrance!! (mere details right? ) PHP: +-----------------------+ Entrance Living w | Dining w w= window | |wwwwwwwwwwwwwwww+ | Kitchen +----+ Modern open lounge/dining areas are anathema to good stereo reproduction.
aaah, I see. Kind of scoobies any alternative speaker placement. Id go with the rugs on floor, behind you, bass traps behind the speakers route. Know what you mean about modern homes... damn architects hides for not designing a listening room ! Chris
That would limit my access to the trapdoor containing my booze . Anyway, repositioned my speakers a lot closer together and toed them in quite a bit more. The mode is much, much less distracting now. Imaging is also better with more focus, although the soundstage is a little smaller. Also, the partial culprit might be my Alpha 9CDP. In comparison, with my DVD player, its a little too warm in the bass. Although leading edge definition is OK, there is quite a bit of overhang in comparison. The Arcam *hits all over my DVD player in imaging, dynamics and all round musicality though.
That corner where the CD rack is looks ideal for some RPG Modex corner bass traps. Or a much cheaper DIY version.
