Axiom Home Page Forums General Discussion Technical Questions Iron Man 2 fluttering

sorry about that cdot2four, i didn't read your post correctly. you definetely need a sub and how big is your room that you can stand listening to movies at that volume?!? I thought me listening to movies at 50 to 60 Absolute was loud (not too loud but loud) WoW, I've got sissy volume levels next to yours!

I know it can happen cause I had the same problem as the OP a few months ago but don't really understand how it can happen! How can a driver be in distress? Specially since the OP has a dedicated amp, the M80s should have plenty of power to play whatever they can? I'm lost...

Because the driver does not have enough displacement to make the sounds it is being asked to.

It is possible to have a 6" driver produce audible sounds in the 25 Hz region, BUT ONLY if it is a very high excursion driver and it is very efficiently acoustically coupled (ie: a larg horn loaded sub )

Since the driver does not have huge excursion and it is not efficiently coupled to the air, all it can do a flap.

In that case, shouldn't the M80s (or other towers) have high pass filters below their -3dB point to avoid damaging the drivers?

Also, the OP has a sub and chooses to redirect the LFE to main + sub, in that I understand, the M80s are asked to play 20Hz and they can't. However, in may case, I have no sub so the .1 should not be played. I thought only the LFE channel would go that low, not the Front channels. Am I misunderstanding something?

The cabinet itself is an acoustic high-pass filter. But put enough power into it, and you'll still cause significant speaker movement. It's not just that the drivers can't play 20 Hz, the air in the cabinet itself will help to impede cone movement below a certain frequency, offing some protection.

There can easily be content down to 5 Hz or so recorded on digital formats. I have CDs with 5 Hz tones. Without a crossover setting those notes would come out the main speakers.

Hi bdpf,

LFE+Main settings allows both the main speakers, the M80's in this case to be set to large playing low frequency content that otherwise would be sent to the subwoofer. Now if you have the crossover of the sub set at 80hz this is the area below the subwoofer will be utilized as well. The best I can describe it as a "double bass" feature.

This is a bad idea in general for a few reasons even for floorstanders.

1) Blu-ray movies have a lot of content below 40hz with even some subsonic content with extreme dynamic range. Loudspeakers are not meant to reproduce such frequencies at reference levels even the M80's. The M80's will sound a lot cleaner and handle more power set to small crossed over to at least 40hz.

2) You have these powerful amps and by having the M80's set to large you are robbing them unecessarily of power and headroom for the mains because instead of having the subwoofer handling the bass scenes which a well designed subwoofer should do well on most occasions (that has its own amp) the speakers are drawing power as well and this is the area the current draw will be the most. The amp for the speakers will be drawing a ton of current and working harder along with the speakers because of the low impedance of the M80's in the low to lower frequencies during those scenes.
Essentially by doing this you are making your amp work harder as well as your speakers especially at loud listening levels. Set to small, use a higher crossover point, a sub and the speakers will handle more power and sound cleaner especially during dynamic passages. Your risk of damaging any of your equipment is much less as well.

Chris and Doc, Thanks for the explanation.

I thought only the LFE channel would go below that, not the FR and FL, ie if you don't have a sub they shouldn't be required to play these frequencies. I guess I am not properly understanding the difference between "regular" bass and the LFE channel.


The reason I don't have them to small is because I don't have a sub yet so I can't cross them over. Even though I rarely watch BD at very high levels, the few times that I did I thought the M80s were doing an amazing job. The only 2 scenes that I ever heard the "flapping" were in IronMan 1 when he goes to Afghanistan and enters sonic mode and in Peter Jackson and the Olympians at the beginning when Poseidon first steps to the ground. Other than that I never heard anything else wrong.

With the LFE+Main setting, the low frequency signal .1 of the main speakers set to large (M80's in this case) are produced simultaneously from those channels and the subwoofer (starting approximately where the crossover point of the sub is set at). This setting creates a "double bass" effect.

The LFE channel isn't supposed to include pre-crossed over audio. Basically if you lose the LFE, you don't lose anything important. It's for Effects: earthquakes, explosions, etc. That doesn't mean there can't be non-effect low frequency content in the mains.

It seems that many receivers when the sub is set to None, it mixes the LFE content into the mains. That used to be disallowed, but appears to be common place now.

So something you may want to try. Don't disable the sub channel in the menu, but leave the mains set to large (don't use the plus mode). That'll at least keep the LFE out of the M80s.

So, in the case of an Earthquake for example, is the rumbling part of the bass or part of the effect?