S35 Center Channel "Popping"

south2027

Hello! I recently upgraded my home theater to digital with an Onkyo TX-NR686. I currently have a 5.0 setup (no subwoofer) with new Polk Signature S20's up front and a Signature S35 in the center (the S35 was picked out of necessity due to space constraints). My surrounds are old Philips satellites which work fine but will eventually be replaced with S15's. Thus far, I'm loving this setup with one troubling exception.

The problem that I'm having is with the S35 making alarming "popping" noises during certain low-frequency sound effects. I should note that I'm only having this problem with a particular BluRay (Star Wars: Rogue One) while listening at theater volumes (60-65) with the receiver set to the preferred DTS-HD Master mode. The issue goes away if I manually apply different audio codecs (which seem to draw back the low frequency sound effects).

I have the Onkyo's center channel crossover set to its 200 Hz max and the LFE to it's highest negative setting. It seems like the really low frequency effects shouldn't even be making it to the S35 (which is rated for as low as 53 Hz), but the "popping" persists. I also checked all of my wiring and switched out the HDMI cable running between the Onkyo and the BluRay player with no change.

I should note that the S35's "popping" happens both when I set the BluRay player's output to bitstream (allowing the Onkyo to do the decoding) or to PCM (allowing the BluRay player to do the decoding). No change at all.

Oddly, none of my other BluRays seem to cause the "popping." For instance, the S35 has zero issues with Harry Potter: Deathly Hallows Part II, which has some pretty deep low frequency effects and also uses the DTS-HD Master audio codec.

In the end, I'm trying to figure out if I have a problem with my Onkyo's center channel, the Polk S35 center speaker, or if this is simply an anomaly limited to the Rogue One BluRay (which I now avoid playing a theater sound levels out of fear of damaging the S35).

Thanks in advance for your trouble-shooting ideas.

mlistens03

First off, welcome to Club Polk!

Is it a metallic kind of clapping sound?

If so, you could be pushing it too hard and "bottoming out" the midbass drivers. This means that the speakers are moving farther than they are capable of, and the voice coilings are smacking into the back of the magnet. Be wary of this, it can cause significant damage to the drivers If continued for too long.

I don't know much about the Signatures but I'd assume they aren't designed for low bass, especially if the S35 is the slim model.

I'd cut low frequencies from the center in the menus of your receiver, and you should be good to go.

Others here are more knowledgeable and may be able to help you if there is more to this issue.

Rock on! -Micah

Clipdat

mlistens03 wrote: »

I'd cut low frequencies from the center in the menus of your receiver

Sounds like he already did that:

south2027 wrote: »

I have the Onkyo's center channel crossover set to its 200 Hz max and the LFE to it's highest negative setting. It seems like the really low frequency effects shouldn't even be making it to the S35 (which is rated for as low as 53 Hz), but the "popping" persists.

If it only happens with the one movie, I would wager that it's something about that particular disc/movie.

mlistens03

Clipdat wrote: »

mlistens03 wrote: »

I'd cut low frequencies from the center in the menus of your receiver

Sounds like he already did that:

Ah. Yes, I see that now. Sorry for filling your thread needlessly OP!

polrbehr

@Clipdat is likely correct, and it could be that particular movie; it also could be the volume level you’re listening to it.
I had a CSi30 center in a similar configuration, and there was one part of War of the Worlds (when the first walker came out from under the street) that would cause that that center to buzz like it was distorting. So it’s not unknown to happen especially with a center that has smaller drivers. And for the record I have an S35 now too.

Welcome to the Forum !

pawelmwo

Sounds like you might not have enough power to drive those speakers to those levels. That receiver is rated at 100 watts per channel into 8ohms for stereo. I'm not too familiar with how absolute volume translates to decibels on Onkyo. But I know around 80 is reference on a Denon so 60 would be -20dB. I'd recommend you set your volume to relative.Your speakers sensivity is 88dB and your receiver's power rating efficiency likely drops to around 70%-75% when you use more than two speakers. How far are you sitting from the left, right and center?

south2027

Thank you to everyone for your suggestions.

To answer pawelmwo's question, my seating position is roughly 12 feet from the S35 center, with the L&R S20's being about 14 feet away. I'm going to try setting the volume to relative per your suggestion.

The "popping" is not what I'd traditionally describe as distortion, but actually does sound like the S35's little 3" drivers are bottoming out in extreme LFE situations during the Rogue One BluRay. It's also akin to the "rattling" a torn woofer might make when being pushed a little hard.

When I purchased the Onkyo and new Polk S-series speakers, I was mostly excited to hear how Rogue One sounded, so that was the first disc I popped in. However, I've since had the opportunity to play several other LFE-intensive BluRays with DTS-HD Master mixes and have had absolutely no issues whatsoever. The S20/S35 combo up front sounds amazing and has been a massive upgrade over my prior setup.

As a result, I'm currently chalking the problem up to being an idiosyncrasy of my Rogue One BluRay. I'll let you know if I run into issues with any of my other BluRays. The Lord of the Rings BluRays are next in my queue.