Subwoofer Question

[RobP]

The other night my family and I were watching the Incredibles and there was one part where a rocket takes off, the bass was quick, low, and loud. My subwoofer which is a B&W ASW850, bottomed out and sounded distorted. I ended up turning the sub level down to a negative 7 on my Rotel processor to finish the movie out. To say the least I was not happy with my high dollar subwoofer. :M The next day I called my dealer and he went over my settings with me over the phone and I had everything set correctly, and even had the level lower than what he reccomended. He was shocked that it sounded like that and told me that it must not be positioned correctly and that I should move it around to find the best spot.
Now I know that placement is important to great performance from the sub ,but can it also cause cancellation to make it distort that bad?? My room size is 14 feet wide by 21 feet long. I have it positioned about four feet from the corner on the right wall facing out, the bass is really smooth on music and most movies but when it hits low fast bass notes it bottoms out. Any ideas here?? :huh:

[georgev]

Positioning is quite important and can cause that effect, however I would get your dealer to check out the sub itself. Thats a top notch sub. and should not really be doing that.
Play around with placement first, and you have a good reference(the scene from Incredibles) to use.
if the sub is not giving you any hassles with most movies, then why on this one, are the frequencies going too low, before a flaw in the sub shows up?
If playing around with placement does not solve it then contact the dealer again.

[Stevebez]

I would say the sub is faulty ... you would need a pretty hefty pulse to get a sub of that quality to bottom. It could be in my opinion ... a problem with the spider / driver , problem with the amplifier ,or it could be loose connections... or it may even be the processor. I think placement would be last on my list of possibilities, but room resonances at those low frequencies play all sorts of tricks. I would try the same passage with the sub slightly further into the corner (i.e. < 4', so try 3' then 2.5'). If it still does it with these changes then it is probably not placement. Check cabling wiring - try a different interconnect lead -you may be getting some shorting in your interconnect ... this may only show itself with a high pulse signal.

I assume this has not happened before ? What was the relative spl of the passage roughly ... VERY loud , Loud or normal movie listening?

I bet its the interconnect.

Rgds Steve.

[RobP]

Well, I re-checked my levels, purchased a new interconnect cable, and moved it around to many different places and still the same thing. One weird thing though, I switched from the "A" EQ setting which is more flat and plays lower to the "B" setting and it didnt seem to do it as much, but the SQ diminshed on this setting. I think it will be making a visit back to the dealer.

[georgev]

That would be neccessary methinks.

[miner]

Please keep us updated on dealer findings.

[RobP]

Allrighty, check this out, right before I lifted this beast of a sub to load it in my truck an idea struck me (I should have checked this in the first place! DUHHHH!! :roll: ). If the sub was bottoming under fast transients then I may have an air leak (being that this is a sealed enclosure). Well it did, the bolts that hold the woofer in were really loose. I gave them a good snuggin and bam! :P The bass cleared right up, the thing was leaking under high pressure. I am going to order a new gasket just to be safe. You guys may want to give yours a check. Im just glad that I found this out before I lugged this thing into the dealer, boy would that have been something! ops:

[junior77blue]

So, no more bottoming out??

[RobP]

No more, all cleared up. Alot tighter.

[miner]

No more, all cleared up. Alot tighter.

Nice job :T DIY repair.

[georgev]

Thx for the feedback. Well done.

[Murunga]

Great to hear SG! Enjoy that bass now! And perhaps this thread may help others too!

Murunga

[rotelian]

You paid top dollar for a excellent sub and fixed it yourself? The problem may have been small, something you could fix, but who knows what else might have gone wrong during factory assembly?

I would take it back and expect the dealer to be happy to exchange it for me.

Just me.

[RobP]

Well, sure I did, I have had my hands in many speakers over the years, alot that I have designed myself for a hobby as well as for customers.Also my time is very limited, so loading up this beast and driving 30 minutes for the dealer to fix something that I can fix myself in a few minutes would be silly. :wink:

[Stoney]

I would not consider loose speaker mounting screws a factory assembly problem unless the speakers were very recently purchased. Although it is probably something most of us would not normally think of, with humidity changes, vibration, compression of gasket material and wood all taken into consideration, I would think an ocasional tightening of the mounting screws could be taken as normal routine maintenance.
Thanks for posting the problem Soundgravy. After the posting, I went and checked my speakers and found they all needed a slight tweak. Mine are all bass reflex cabinets, so I expect no dramatic improvements, but it's nice to know everything is all snugged up. I frequently check the speaker wire binding posts also.

[Mark_C.]

I think I would take it to the dealer just to have it checked out. At least for peace of mind. Glad it's working.

[PewterTA]

This is why I like ported subs... Tends to be less of this type of thing (though I go around ever three months and tighten all the screws on all my speakers)...

Good to hear that it was a quick and simple fix. If it's play fine, there's NO reason to take it to your dealer. It's a waste of time... If you notice any other problems with it over the next few weeks, then I'd consider taking it...but not until then!

[caleb]

It's a fact that the mounting screws do work loose from time to time.

It is not a factory fault and normally just a quarter turn with an allen wrench solves the problem.

As a routine I always check mine one a year.