Holy sub rattle Batman!

[darien87]

Hey folks,

I've never used a sub isolator like a subdude or Auralex Gramma before, but last night I popped in the Kung Fu Panda BD just to check out the "Skadoosh" scene because Emotiva recently made a change to the bass management of the UMC-1 and some people were complaining about a lack of bass.

The scene sounded just fine but when the big bass hit happened the Logitech remote charging cradle which rests atop my Rythmik sub rattled like hell and almost fell off the sub! Does this mean I need a Gramma?

 

[adwilk]

Does this mean I need a Gramma?

There ya go...

Sounds like it might be worth a shot in your case. Those vibrations can make some nasty sounds. What kind of floor/subfloor?

 

[darien87]

There ya go...

Sounds like it might be worth a shot in your case. Those vibrations can make some nasty sounds. What kind of floor/subfloor?

Sorry, should have been more specific, carpet on concrete.

 

[adwilk]

Sorry, should have been more specific, carpet on concrete.

Hmm... Yeah, I guess it might help. Its my understanding that the (properly constructed) enclosure itself shouldn't vibrate like that on its own, but it is possible to resonate the floor in a way that would cause the enclosure to vibrate. Decoupling would certainly alleviate the issue. I know that sub has some horsepower, but thats impressive over concrete.

 

[adwilk]

Was your other sub on too???

 

[darien87]

Hmm... Yeah, I guess it might help. Its my understanding that the (properly constructed) enclosure itself shouldn't vibrate like that on its own, but it is possible to resonate the floor in a way that would cause the enclosure to vibrate. Decoupling would certainly alleviate the issue. I know that sub has some horsepower, but thats impressive over concrete.

Yeah it was crazy. I never had this happen before, but the 12" was in a different spot at the old house and didn't have anything on top of it.

Perhaps it was some kind of interaction between the 12" and the 15" that was causing the vibration but was just evidenced on the 12" who knows. Bottom line is there is some serious vibration going on there.

 

[darien87]

Was your other sub on too???

Indeed it was.

 

[j_garcia]

Gramma will not solve that problem unless you put it under the cradle. Just get some foam or something to put under the cradle and should take care of it.

 

[adwilk]

Perhaps it was some kind of interaction between the 12" and the 15" that was causing the vibration but was just evidenced on the 12" who knows.

Thats a likely scenario. Better get two grammas.

 

[darien87]

Gramma will not solve that problem unless you put it under the cradle. Just get some foam or something to put under the cradle and should take care of it.

LOL

Just picturing a big *** piece of foam on top of my sub with a charging cradle on top of it.

 

[j_garcia]

The Gramma did wonders for my previous Tempest, but doesn't do anything for the Empire and my living room is carpet over concrete too. I set all kinds of things on top of the Empire and nothing vibrates.

 

[Alex2507]

I'd be checking to see that the driver was properly fastened to the enclosure.
The enclosure vibrating that much doesn't sound right.

 

[lsiberian]

Hey folks,

I've never used a sub isolator like a subdude or Auralex Gramma before, but last night I popped in the Kung Fu Panda BD just to check out the "Skadoosh" scene because Emotiva recently made a change to the bass management of the UMC-1 and some people were complaining about a lack of bass.

The scene sounded just fine but when the big bass hit happened the Logitech remote charging cradle which rests atop my Rythmik sub rattled like hell and almost fell off the sub! Does this mean I need a Gramma?

The top of your sub is not where you place a remote.

A Gramma or subdude is to raise the sub off the boundary known as the floor and makes bass response tighter. It can certainly help absorb a rattling sub, but a low enough frequency at a high dynamic volume will shake anything and everything no matter what you do. Those are the times you cherish your beloved subwoofer. Any hope those heads of your many conquests don't come crashing down especially the ones with antlers.

 

[lsiberian]

I'd be checking to see that the driver was properly fastened to the enclosure.
The enclosure vibrating that much doesn't sound right.

I suppose it's possible, but I can assure you my sub is built like a tank and the cannon scenes in Master and Commander do vibrate things in the room if I have it cranked up.

 

[adwilk]

The top of your sub is not where you place a remote.

A Gramma or subdude is to raise the sub off the boundary known as the floor and makes bass response tighter. It can certainly help absorb a rattling sub, but a low enough frequency at a high dynamic volume will shake anything and everything no matter what you do. Those are the times you cherish your beloved subwoofer. Any hope those heads of your many conquests don't come crashing down especially the ones with antlers.

If you were to decouple sub one from the floor which is coupled to sub two, wouldn't you in theory decouple the subs from eachother? I actually don't think the rythmik would vibrate that much on its own. I also highly doubt the other sub (elsewhere) in the room would be able to vibrate the rythmik enclosure playing the same frequencies. I actually think the grammas would help. A sub enclosure should not do that.

Now, on the other hand, its possible the bass matched the resonant frequency of the cradle and shook the bujeezus out of it, rythmik enclosure standing stable...

 

[mike c]

Gramma will not solve that problem unless you put it under the cradle. Just get some foam or something to put under the cradle and should take care of it.

hmm, i had a subdude on top of my sub so i could place a fan and other stuff on top of it ... and it still vibrated the hell out of the intercom. i ended up just moving the intercom.

(no i did not put the subdude to kill vibration, but only to protect the sub's surface)

 

[annunaki]

To me this points to the enclosure itself. A well braced enclosure will be much more resistant to this effect but even the strongest constructed enclosure can rattle in such a way if the frequency is right and the output level high enough. Sheer weight can help reduce this effect.To truly eliminate this effect however, one would need to utilize a constrained layer style construction of the enclosure or cancel the force such as in a dual opposed design.

 

[jinjuku]

You could take a blanket. Fold it square and throw it under the sub. See what happens.

I had ceiling HVAC vents that rattled like crazy in LFE scenes. I simply used some foam double stick tape on them.

 

[Warpdrv]

I'll tell you - I'm not afraid of very many scenes with my subs, but that Skadoosh scene in KFP is scary and pushes the limits beyond what I have experienced with any, and I mean any other movie scene for bass - and I mean potentially damaging bass....


It has such a huge dynamic transient spike for super low bass that with enough power it will push the drivers out past their limits quickly....

My Subs don't shake with their dual opposed design making them completely inert, but the drivers go flippin crazy... Worries the hell out of me...

 

[darien87]

So I checked the bolts on the sub and a few of them weren't completely tight so I snugged them up a bit. There was one that wouldn't tighten so I think that one's stripped, but 7 of the 8 bolts are nice and tight.

For shits and giggles I tried putting a couple of foam knee pads under a couple of the legs of the Rythmik sub and played the Skadoosh scene again, viola almost no shaking of the remote cradle. Guess I'll stop by Guitar Center today and see about picking up some Gramma's.