Annoying Flapping sound from S20

ttbhai

Do you know what is this sound called, and why does it happen in S20?

My speaker configurarion:
Denon x3600h with sound level at 80.
4 polk S20
4 Sony SsCSE
SVS subwoofer NSD
Polk S35

5.1.4 atmos configuration. Calibrated using audessy.

This flapping sound happens in all polk S20 during any fight or action scene having rumbling or high bass. Happens in all S20 speakers and in all the movies and is quite annoying when all 4 S20 does that during critical scenes.https://youtu.be/Irr3uIpRXiE

txcoastal1

Are your speakers set to small?
What crossover point are you using?

Clipdat

The woofer is bottoming out. Check the crossover setting for that channel and increase it to 80hz or higher.

F1nut

Take the protective plastic cover off your speakers while you're at it.

tonyb

Sure looks like they are bottoming out, which means you have something in the settings way off, or how you have them hooked up isn't right either.

More info and we can help you better. For now though, stop playing them like that or you will destroy them.

ttbhai

First of all, thank you so much for replies. My background- I am an engineer so can understand technical stuff - so , can interpret your suggestions. Though certainly not an expert in audio, yet, and learning as I go. So any thoughts or suggestions from you guys will be a great help! Thanks again!

Yes I guessed it might be something to do with cross overs and large small settings. But not sure what is the best setting.

Below is configuration (I have also attached some pics for your ref).

Speakers config:
Front: Large
Center: small
Subwoofer: 1 speaker
Surround: large ( by the way, there was no option for only rear surround in denon (i.e. without side surround), so had to select surround on side, but really speakers are placed in rear on sides angled towards me. i.e. behind sitting position. Which is an issue with Denon. I also have pioneer with different speakers and that does have flexibility of putting speakers on sides or behind me)
Front height (sony sscse as height): small
Surround dolby: small


Cross overs:
Speaker selection: individual
Front: 40 hz
Center: 80hz
Surround (rear): 40 hz
Front height: 80 hz
Surround dolby: 100 hz

Speakers/Bass:
Subwoofer mode: LFE+ Main (dont know what this means)
LPF for LFE: 150 HZ (I have set subwoofer to LFE and gain is set to 75 db as instructed by Deno during auddessy calibration). It is SVS SB12 NSD and dial starts from 30 hz)

I had read in some post that you have to select front and surround as small but thought it might be for small tiny speakers. Was thinking since these are S20, might be called large.

So I guess I will try changing the front/surround speakers to small and cross over to 80 and see if thsat makes a difference.

Though few questions:
Would that mean I am under utilizing the speakers?
Should I also change LPF for LFE to 80 HZ (from 120 selected by audyssy)?
And would that mean I would need to run audyssy calibration again?

ttbhai

Second pic

ttbhai

Last pic

F1nut

Set ALL speakers to small. Use the LFE option at 80Hz.

txcoastal1

^^^what he said

When you have a sub using LFE, and speakers are set to small...80hrz crossover, this directs the sub to handle most signals below 80hz

If you set to large all speakers full range and when watching movies especially smaller speakers will eventually blow, or you will lose a channel on your receiver.

Plenty to google about the subject...and home theater using a subwoofer

Your fronts are set at 40hz...per Polks specs for the 20's peak response is 39hz
Borderline at low volume...critical at high volume

https://www.polkaudio.com/products/s20

ttbhai

Thank you so much.

So yes, just set all to small and set LPF to lFE at 80, and the flapping (as I call it continued).

So as next step, initially moved crossovers for front/surrounding to 60 (from 40), and it improved a lot. Though still noticed slight disturbance. Though watching starwara, so not fully sure if thats noice or expected rumble from soundtrack. I think its more of disturbance than sound track.

As third step, keeping LPF for LFE still at 80, changed cross overs for front/surround from 60 to 80, and that sounds preety smooth. Below pic is where I am tending to land (flapping gone for sure, not 100% confident if at 80 instead of 60 if I am missing any rumble sound tracks).

(Fyi, also changed front height and surround dolby to 100, instead of 100 and 120, guessing, to get more height effects. Wondering if should height be at 100 (front) and 120(rear dolby) as it was, or both same either 100 or 120)

ttbhai

ttbhai

Oh right, i forgot, sub would still handle below 80. So by setting front/surround at 80, i wouldnt miss out any signal. Though question about hight crossovers still remain. 100 and 120 vs all 100 vs all 120

txcoastal1

Per the last pic your settings look correct. Run Audessey again ...turn off all fans, AC and family must be quiet..LOL...seriously works best with list or no background noise.

You be all set...keep us posted and welcome to Club Polk
Bsafe

ttbhai

Thank you so much!!!

If I run audessey again, won't it change all the crossovers back to where it had initially set them? I thought these cross overs were set by audessey to begin with.

F1nut

Think of Audyssey as the first step, which it is as it is far from perfect. The next and final step is to tweak the settings to what actually works and sounds good to you.

Out of the 3 calibration programs, Audyssey, Yamaha's YPAO and Pioneer's MCACC I've found MCACC to be the best. Still, I tweak it to my liking after running it and it's got so many tweaks it'll make your head spin.

ttbhai

Thank you.

Yes I have a pioneer LX 303 receiver as well that I am using for a smaller klipsch system, and even though its less than half price compared to denon, I love its calibration process, and I think I find it same or better sound quality compared to denon.

The biggest turn off for me in Denon is (on the top of lengthy calibration which did it wrong), is the surround speakers (it would show rear surround only as a step next after saying yes to side surround. And if I do that , at the end it would only let select 2 height speakers as I ended up wasting 2 channels for side speakers just to get to next step). On top of that during calibration it shows 7th and 8th position behind couch where nobody would ever stand.

Anyway, Really appreciate help from all of you. I think for now I am set. Will keep twiking height channel frequencies, but the main problem is solved.

So thank you so much for quick responses and help !!!

F1nut

Thanks for your follow up post.