Where shouldn't my sub go?

[kyleseager]

I have had a sub for about 3 weeks now and I currently have it directly behind my tv stand, which is situated in a bay window so directly in front of the wall. Now I hadn't had any problems with this until I was watching a film today and when a car crashed my dvd player stopped. Now this is almost 100% because of the vibrations from the sub, so should I be worried that the sub could be causing damage to my hifi gear? I have my amp, xbox, dvd, plasma and centre speaker all directly in front of the sub, i.e. within 20cm. Is this going to be a problem?

Cheers for any pointers.

Dammit, why can't I spell? That should obviously say sub not sib. Oops.

[recruit]

corrected

[kyleseager]

Thanks.

[kyleseager]

Anybody?

[CasDon]

I've seen a few people recommend the corner of a room, but not tucked into the corner if you get my meaning.

I used to have my sub flush along side the TV unit until two weeks ago I was watching a film lay down on the sofa with my head a the end of the room the sub is in and noticed a huge boomy difference in the base.

I've since moved it away from the unit diagonal across the corner of the room, min 6inches from each wall and the bass is far better distributed.

I think in general though its a case of what works best for you.

[kyleseager]

Thanks for the info.
The sub sounds really good where it is, I was just worried about the vibrations from the sub damaging any of the equipment. I will move it around a little tonight to see what it sounds like elsewhere away from the rest of my gear.

[CLIVEEDWARDS]

If its vibration on the floor boards you could try and isolate the sub from the floor. If however sound pressure is the problem move it before your plasma lands butter side down.

[Morb]

You could also look into isolating your dvd player i guess.

Have you eq'd your sub, or run test tones atleast to see if you have any large peaks that might have caused this to happen?

I have my sub right next to my amps, dvd player, cd player, digi box, xbox 360, center speaker, plasma and the right front speaker and have never had anything skip. My floor is wooden with huge cavities underneath them but my sub is placed ontop of a big thick piece of foam, maybe that is the reason i have no issues with mine. I do play it loud aswell on occasion.

Moving your sub about might help if it is caused by a large peak, you might even find a spot it sounds better in to boot.

[Nimby]

The AV equipment doesn't know (or care) if there is a room mode peak at the listening position.

If the sub is placed so close the equipment gets a nearfield response without room gain.

Nearfield is at a much higher level than at any reasonable distance.

Don't point the sub driver directly at the equipment if it's a front firing subwoofer. Float the sub on a slab on something soft to isolate it from the floor (if wooden). Don't bother if it's a concrete floor.

Difficult to know what else to suggest. How about a large, vertical slab of marble between the sub and the equipment rack to isolate the sub from the delicate equipment?

You need high mass to avoid sympathetic vibration in the isolating panel. What about a bit of kitchen working surface? Cheaper than marble and less brittle. Usually about 2" thick chipboard and covered in Formica. Stand it up on edge between the sub and the rack but not touching either. Choose a finish that doesn't clash with your room. Make sure it is safe when standing on edge. A strut back to the wall or window frame behind will stop it toppling. Avoid a panel altogether if you have toddlers unless you make it really safe.

[kyleseager]

Thanks for all the info guys. I will try moving the sub around first. In all fairness it has only happened the once, but if it happened once it can happen again. I think I'd rather move the sub anyway as it's hard to get to switch on and off. I originally put it where it is, not only because I liked the sound where it is, but also to hide it from the missus, but since she has spotted it now, there'sno point hiding it anymore.

It's a DF by the way if that makes any difference.

Thanks again.

[Tag user]

All I'd say from personal experience is NOT to put a sub near the other equipment . . I just cant as it has made several different dvd/cd players skip . . but then again I have probably dialed out my sub now . . nice and subtle,but when theres something for it to do,you know its being done with ease . . .also tucking a sub into corners or even boundary loading it (close to walls) can totally ruin things

[Knyght_byte]

might be worth using the old squash balls cut in half trick under the DVD player...

my PB12+ is only a couple foot from my rack of equipment, but my Denon 3910 is a sturdy beast (almost a fifth of the weight of my sub!) so i dont worry, never had any hiccups, even during Jurassic Park moments...lol

[jkharmer]

Can I just butt in (sorry), would it be better to put a sub on the opposite wall to another house (in a semi-detached house), or does it not really matter as the sub will be heard next door no matter where it is located in the listening room.

Thanks, James

[Morb]

Originally Posted by jkharmer

Can I just butt in (sorry), would it be better to put a sub on the opposite wall to another house (in a semi-detached house), or does it not really matter as the sub will be heard next door no matter where it is located in the listening room.

Thanks, James

You would think that not having it next to your party wall would be best but it is as far as i am aware more complicated. Lots of strange things happen with low bass depending on your room and other factors, and we can't forget the fact the lower bass tends to travel very easily. Maybe just have a chat with your neighbours and see how where you place it effects them next door.

Of course i could be totally wrong and it might well be better away from the party wall, but i would still suggest having a chat with your neighbours and find something that works for both of you. Who knows you might be able to run it louder than you thought.

[Nimby]

The highest sound pressure levels are always at the sub itself.

Even if there are higher bass levels against the opposite wall they will still be much lower than close to the sub itself due to the losses over the length of the room.

Mechanical vibration will also be higher at the sub than elsewhere.

I would avoid placing subwoofers or speakers against the party wall.

Get out your SPL meter and test local levels for yourself. Levels fall rapidly as you move away from your speakers or sub.

For example: In my 9 meter (27 feet) long AV room running REW test tones I set my IB to 85dB(C) at the sub mouth. This falls rapidly to only 70dB(C) within only 2 meters. Then right down to 53dB a yard from the far wall. At the wall itself there is a rise of between 3 and 6dB within an inch or two of the wall surface. I was using a Galaxy 140 SPL meter set to C-Slow. This meter is much flatter at very low frequencies than the popular RS meter.

Tones from 10 to 80Hz all followed the same pattern with slight variation in SPL towards the middle of the room. Check the "Frequency follows cursor" box in "Generator" under "Tools" in REW for a fun audio frequency generator.

Do not persist in high levels at very low frequencies for more than few seconds. You may not hit the end stops but you might fry your driver voicecoil on some subwoofers!