Recently I adjusted the subwoofer output level on my NAD receiver because I wasn't getting the bass output that I wanted from my EP500. So I set the level to plus 5, and adjusted the volume on the EP500. However, I found that when I adjusted the sub output on my receiver, the EP500 occasionally made this popping noise from the cone during extreme LFE tracks. I thought it was just a fault with the audio track on this particular movie, but it happened on multiple movies. Does anyone have any suggestions?

I know that it is supposed to be impossible to clip an EP500, but that sure sounds like what is happening to me. I adjusted the sub level back to 0 on my receiver and that seemed to fix the problem, but it really makes me wonder.

You could be clipping the output of the receiver. A clipped signal going into the sub will result in clipped output.

As usual, Chris is 100% correct.

If you want more output from the sub turn IT'S volume/gain control up and try to keep the avr setting near zero. If this still doesn't give you what you want it is time for multiple subs or a bigger one or both.

Or just a new location. As many will tell you, with subwoofers, it's location, location, location.

Locating the sub in a corner is another potential way to increase it's apparent output.


Have you tried the sub crawl? Maybe you are just listening in a dead spot in the room.

Did you just purchase the EP500 recently? Supposedly on the newer EP500 individuals have noted they have to increase the pre-out signal significantly on the receiver to get the output they wanted. This was never a problem with the older amp versions. Certainly having the sub pre-out level set to +5 could produce this "pop". Turn down the sub pre-out to around +1 or +2 and turn up the gain control on sub to compensate (as much as you need).

As for being impossible to clip the EP500, if you try hard enough you can get ANY sub to make unwanted sounds such as "flapping", "rattling" and "popping".

Not if the sub is DSP limited. That sub is happily running within its limits and reproducing exactly the signal fed to it.

Bolt, you can sleep well tonight knowing that the EP500 is giving you the most accurate reproduction of receiver output clipping money can buy.

To answer a few questions;

I do have a newer EP500 (Purchased in the last two months)

I know I should do the subwoofer crawl, but my placement options are extremely limited, so I didn't bother. My house is not very ideal at all for audio.

As far as the gain is concerned, I had the volume turned almost all the way up and it was barely hitting. That's why I wanted it a little louder. I think I have it at a little more than 3/4 of the way up.

If you're seating area is in a bass null, turning up the volume, or even putting a second sub in the same location will make no difference. In a null, you have reflections that put sound waves in a given frequency out of phase, so they cancel each other out. Turn the volume up on your sub and you turn up the volume on the out of phase sound wave.

If you can't move the sub, can you shift your seating a little to see if that improves the bass?

Yes bolt148. Your experience with the newer EP500 version has been consistent of individuals that have received the newer EP500 units with the re-designed amp. I hope axiom looks into this issue further. The newer amps they have designed don't seem to live up to the previous version. I would be hesitant to recommend them.

I will try that.

I thought that the built in Audyssey room correction on my NAD T747 would fix that issue?

I have noticed that the bass changes as I move throughout the room, but I was under the impression that the receiver equalizes the sub to get the best response at the current seating position.

There is nothing you can do to equalize a null because anything you apply to the signal applies equally to the out of phase wave as well.

Audyssey is a not a fix all, it only attempts to equalize what it can within it's somewhat limited range and if the Audyssey you are using is an older version, it may well be killing the sub to equalize the room. Try running the system without Audyssey.

To further the idea of moving a sub. I found that simply rotating the sub within it's normal spot can help with the way it sounds. I went from straight out 90deg. from the wall, to facing the opposite wall at 45 deg., to firing directly into the side of the couch which was the best sounding placement.