Axiom Home Page Forums General Discussion Home Theater Iron Man 2 Blu-ray

First I swapped the speakers between the L/H and R/H channels to rule out the receiver and the problem stayed with the speaker. Then I swapped both the tweeter and midrange drivers (couldn’t be sure where exactly the sound was coming from) between the speakers and the problem stayed with the cabinet and didn’t follow the drivers. I checked for anything loose in/on the cabinet and found nothing so I emailed Axiom with the results of my troubleshooting.

Got a quick reply the it was probably a bad crossover and they would ship me a new one. Since I installed the new crossover there have been no problems.

What is the starting and ending time on the scene?

Once I had a problem with my m80's where a wicked vibration would occur at certain frequencies. I swapped speakers and it stayed with the speaker (not the L/R channel) so I thought the problem was the speaker. However, after swapping grills I noticed the problem followed the grill. After closer examination the grill appear to have some wear on one of the grill posts that was not "snapping" in and leading to vibration of the grill against the m80.

Axiom sent me a new grill and I haven't had any problems since.

Dean, very good approach, I will try the same.
Dr, I will let you know tonight the exact time of the scene.
Thanks guys.

I was just going through my BD copy of Iron Man and I think I know which scene you are talking about now. It occurs at approx 1:16. There is defintely some demanding low frequency content present in that scene and the one right after with the explosion. If you can isolate the noise to just the bottom two drivers which handle the bass reproduction on the M80's, the drivers are probably having a hard time reproducing those scenes without distortion.

If you can isolate the sounds to the entire speaker, the amp clipping the signal is more likely. I suspect it is the former and not the latter.

When you say bottom 2 drivers, you mean the 2 woofers on one speaker or the bottom woofer on both the L and R speakers?
I will need to recheck but it seamed the noise was only coming from the right channel. If it's a problem of the M80s not being able to reproduce these frequencies, shouldn't it come from both speakers? I guess a good way to find out is to swap the L&R channels.

I was referring to the bottom 2 6.5" woofers on the suspect right channel. Since you are not using a sub and are running the M80's full range I am not familiar with how low frequency content is mixed into the mains in these situations.

That particular scene at 1:16 Iron Man pans from the left to right in the sky. Swapping the L and R channels is a good idea.

The LFE channel should never be mixed into the mains when a receiver is set to no subwoofer. That's a decree from Dolby, and from what I understand it is followed by everyone.

That doesn't mean that the main channels can't have their own < 100 Hz content that will still get played. The LFE channel is designed to contain effects, like textured rumbles. While the main channels contain content sensitive information, like the sound of an explosion.

Because of this recommendation bass notes of music, no matter how low, should never be mixed on the LFE channel, because with no sub, the notes would not be heard.

OK, so I had a chance to troubleshoot my problem. I worked only with only channel on the receiver. First I connected the speaker that seemed to have the problem, and the rattling noise was there. Then I connected the other speaker, the woofers were having a hard time reproducing this scene but no rattling. It was hard to hear which woofer was creating this noise but it seemed to be the bottom one so I swapped the bottom woofer from the right to the left and the noise followed the woofer so I contacted Axiom and they're gonna send a replacement.

Now, I would love to leave my M80 set as full range but would it be safer to set them as small with a crossover set at 40Hz so they're not trying to play frequencies that they can't play properly?

The other concern that I have is that I've had these drivers for a few months and only happen to notice this problem by luck (right scene at the right volume) so it makes me wonder if I don't have other problems that I am not aware about. Is there something that I can do to test if all the drivers are working properly including woofers, mids and tweeters? Something that would have shown me this problem on day one? Thanks.

You can try some frequency sweep test tones (Google for that). They should sound smooth and not evoke odd sounds from the speakers themselves (I get odd sounds from different things in my apartment on the low frequency sweeps).