Axiom Home Page Forums General Discussion Home Theater Subwoofer POP

I'm hoping someone can tell me why this happens. There is a LOUD POP coming from my sub. In the past in only happened once during a movie. Today i played around with the sub and wanted to see how high it could go. I out the trim on almost max.... Usually I have it at 9' o'clock. Anyways I was playing far cry 2 and every so aften when i threw a granade the sub would pop very loud. This isn't how i normally run the sub so I guess it's not a huge issue, but I am curious if it's damaging the sub to run it that high? Also this did happen once before when I had the sub trim at 9' o'clock. It's the new ep350 by the way.

Thanks in advance.

You are driving the sub into clipping, that's the "pop" you are hearing.............over excursion of the driver. You WILL ruin the driver if it continues.

Thanks I will make sure not to drive it that hard again. It did happen once during normal use however, which worries me.

Your playing games? Computer or Game System? If computer it might be your sound card is crap, not sure.. Should be no reason why you would max out your sub volume, unless you don't have things calibrated on the receiver correctly.

on the ps3. I just wanted to see how loud it could go that's all. I only played that way for 30 seconds or so until i heard the pop. My walls shook too.

My 350's are calibrated to the rest of my speakers, around 75dB using the receivers test noise. I've played very very low subwoofer test tones from youtube at very loud levels, clear, low, and no pop.

Now you have me worried. I've had the same sub about 2 months and have noticed on a couple of movies a high pitched squeak from the sub during a couple of high LFE scenes. No, there are no animals inside. I could reproduce it on those scenes. I was running it at the 10 o'clock position so while it was at a high volume I don't think it was really up too loud. I hope this is not an ongoing issue as it sounds great for music but it sounded really bad when it occurred during the movies.

Wow guys, not sure. Both my 350's up front are about 1 o'clock, and my 600 in the back is at 6 o'clock, receiver at 0dB. Now my room is very large so that could play a part in my settings. I've never experienced any strange noises for any movies.

Their input levels might be clipping as well..

Could you explain what you mean by this to a noob like me?

I too was able to reproduce this effect during a particular scene in a movie. At first I thought it was there from the source, but it wasn't.

Mark can you elaborate? What do you mean clipping from the source? What could cause this? I am using the 2809ci to drive the speakers by the way.

The input signal from the game could just be too hot during those scenes and the receiver ends up clipping the signal to protect itself.

Listener - one more elaboration on Mark/Jay's posts. (I think) what they're both saying is that the sound is recorded into the game at an extremely high level compared to the rest of the sound and because of the big dynamic range (volume difference between soft and loud sounds), even if you are listening to the normal game sound at moderate levels, when this particular sound comes through, it is at such a high level that the receiver has clips (makes that sound you're hearing) to protect itself.

I see. So does this mean that it would prevent the subwoofer from damaging itself?

its your input source i bet, not the sub... but that doesn't mean it can't be good on your sub.

I know the dsp in the 500 basically won't allow harmful signals to pass to the driver and I would assume the 350 is the same way. It, very eloquently, will trim back the signal instead of just clipping it.

I have had times when my input source gets a bit scrambled (digital decoding) and a bunch of loud and unpleasant noise outputs a high volume... that may be your problem also.

Nope, the 350 has no DSP. What goes in comes out.

If it's popping like that, it doesn't sound good to me.

Hi Listener,

As kcarlile has pointed out, the EP350 does not have a DSP, so it is possible to overdrive the woofer, in which case, the voice coil will hit the magnet structure at the back of the driver when its excursion is too great. Sometimes that will make a noticeable "snap" sound.

There could be any number of reasons for what you are hearing. It does sound like some type of clipping somewhere in the amplifier chain rather than over-excursion of the 350's driver. It's a very robust driver, the same as the EP500's, but without the DSP circuit I suppose it would be possible to overdrive it.

What I described above (the voice coil hitting the magnet) is a nasty mechanical sound and when you hear it, turn down the level immediately so no damage will ensue.

Regards,
Alan

Thank you Alan and every one else who responded. This should not be a problem going forward since I will not be turning up the dial on the sub that high again. I do have to say that when I did this it produced almost "wall shattering" bass. I liked it. I liked it a lot. If I wanted to be able to reproduce this safely I guess that means upgrading to the ep500.... or perhaps the 600 or 800....

EP800, the lower extension is what really gets things shaking.


I sure love spending other people's money

Listener, there is no reason you can't run your sub a little hot, just not cranked all the way up.... I would calibrate it with the other speakers, say 75dB, using the receiver or other test tones. Then, bump it up a few dB's until your satisfied..

I set all 3 of my subs, one at a time with the others off, to the same as my other speakers. Then once they are all on, combined are about 5dB's above the other speakers.