PSW505 Subwoofer bottoming out?

kuntasensei

Again, from Prof. Chris Kyriakakis of Audyssey, who can explain better than me:

The most confusing part for most people is the LFE setting. Unfortunately people use LFE and Subwoofer as if they were the same thing. They are not! LFE is a separate track found only on 5.1 content. It is directed to the subwoofer speaker in addition to the bass from all the other speakers.

To add to the confusion, manufacturers offer an LFE lowpass (LPF) filter setting. They should not! During authoring of the content, the LFE track is limited to 120 Hz. So, any other setting for the LFE lowpass filter is incorrect! It should always be 120 Hz and, in fact, should not be adjustable by the user.

And another quote:

A crossover is a pair of filters that sends the high frequencies to the satellites and the low frequencies to the subwoofer. There is no such thing as a subwoofer crossover. That is often confused with the LFE filter in the AVR that only applies to the separate LFE track in 5.1 content. That filter must always be set to 120 Hz because that is how movie content is authored.

And another:

Please keep in mind that there is no such thing as a "sub crossover". A crossover is applied to the satellite and sub simultaneously and requires two filters: one that sends the high frequencies to the satellite and one that sends the low frequencies to the sub. The confusion comes because manufacturers are allowing consumers to also set the LFE filter for the subwoofer. That is a filter that only applies to the separate LFE track found in 5.1 content and not to the bass from all the speakers. It should always be set to 120 Hz because content in that track is authored up to 120 Hz.

xxmastermushxx

The OP doesn't have a choice but to have his surrounds at 120Hz, but since mixers don't typically place deep bass in the surrounds, he's probably okay.

Actually, Audyssey crossed the surround satellites over at 100Hz. When I look at the EQ Check it says the surrounds are 0Db at 63Hz. Here's pictures of the EQ check: Attachment not found.

kuntasensei

Your attachment didn't work, but it's irrelevant. The EQ check only gives you a broad picture anyway. 100Hz isn't the worst setting for surrounds, and hey... it's what you have to work with. The question is: Are you happy with the sound? Everything else is moot.

xxmastermushxx

kuntasensei wrote: »

Your attachment didn't work, but it's irrelevant. The EQ check only gives you a broad picture anyway. 100Hz isn't the worst setting for surrounds, and hey... it's what you have to work with. The question is: Are you happy with the sound? Everything else is moot.

Yeah, I'm happy with the sound. You should of heard the surrounds I had earlier, absolutely horrific.

Here's the attachment if you care to look at it: EQCheck Audyssey & Flat.pdf
Do you think I could just set the surrounds at 80Hz? Do you think it would make any improvement?

xxmastermushxx

(Sorry for double post)

I've ordered the mic/camera stand. Should be here in 2-7 days, shipped UPS ground.

kuntasensei

I wouldn't set the surrounds lower than Audyssey detected, because Audyssey actually doesn't EQ past that point. With Audyssey, you can go UP (like 40 to 80) with no problems because it just tosses out the equalization below that point... but you don't want to go down.

Again, keep in mind that those equalization checks are a very coarse representation of the equalization that Audyssey performs. MultEQ actually does hundreds of adjustments per channel.

I see that you have it in Audyssey's Flat mode. If you feel it's too bright that way, try the Audyssey curve instead. The Audyssey curve has a slight rolloff of highs to compensate for the fact that movies are mixed for larger spaces than your home theater. You may be happy with it as-is, but at least you have the option.

xxmastermushxx

I see that you have it in Audyssey's Flat mode. If you feel it's too bright that way, try the Audyssey curve instead. The Audyssey curve has a slight rolloff of highs to compensate for the fact that movies are mixed for larger spaces than your home theater. You may be happy with it as-is, but at least you have the option.

Wait...you can change it? I didn't know that, how do you do that?

kuntasensei

It should be under your Audyssey options. Denons let you pick between Audyssey (the one with the rolloff for home theaters), Audyssey Flat (flat across the board), and Audyssey Byp L/R (leaves mains unequalized).

xxmastermushxx

kuntasensei wrote: »

It should be under your Audyssey options. Denons let you pick between Audyssey (the one with the rolloff for home theaters), Audyssey Flat (flat across the board), and Audyssey Byp L/R (leaves mains unequalized).

Oh yeah, that. I have it on Audyssey, I thought you meant something different. Where did you get it that I was using Audyssey Flat?

xxmastermushxx

I was looking around at what people thought about positioning sub-woofers behind the listening position. Here's what this one guy said: http://forum.hsuresearch.com/showthread.php?t=3855&highlight=crossover

What do you think?

kuntasensei

xxmastermushxx wrote: »

Oh yeah, that. I have it on Audyssey, I thought you meant something different. Where did you get it that I was using Audyssey Flat?

Because that EQ check screen said FLAT. But then, I'm not familiar with the Denons, so I just assumed.

As to your link, everyone starts to localize bass at different points. 80Hz is just kinda' the generally accepted safe point, though it really is up to the individual's hearing.

However, you should know that when he says, "The LFE channel can contain information up to 120Hz that can get lost with a lower crossover point", that doesn't apply to you... because modern AVRs don't have this issue. Older AVRs would take the lowest crossover setting that you set and apply that as a global filter for the entire subwoofer output, meaning if you set all your channels at 80Hz, the LFE channel would be truncated at this point as well. The inclusion of a separate LPF of LFE prevents this, and modern AVRs have been redesigned so that the per-channel crossovers occur before the summation of the managed bass with the LFE channel so that we can have greater control over the LFE channel itself (i.e. level adjustment of the LFE channel compared to managed bass, LPF of LFE, etc.). When you're searching around for information about crossovers, you're going to find a lot of material that talks about the way it used to work - lowest crossover being the cutoff for LFE as well. Fortunately, this isn't the case anymore.

mystik610

kuntasensei wrote: »

If you set your mains at 120Hz and LPF of LFE at 80Hz, the 120Hz sound from the mains still reaches the subwoofer intact and changing LPF of LFE won't affect it one bit.

Makes sense actually. I've always thought the LPF of LFE corresponded with the bass being redirected to the subwoofer channel. I admit being wrong ....I was speaking primarily form experience having had a lot of issues with location, but it appears the localization I was hearing came from using an 80hz CROSSOVER Point

mystik610

xxmastermushxx wrote: »

I was looking around at what people thought about positioning sub-woofers behind the listening position. Here's what this one guy said: http://forum.hsuresearch.com/showthread.php?t=3855&highlight=crossover

What do you think?

The link you're referring to above relates to the HSU MBM-12....its a mid-bass module designed to play strongly in the 50-150hz range, and support both the subwoofer and the mains in the mid/upper bass regions. It behaves a little bit differently than a subwoofer, and given that it has a roll-off at 50hz, it technically isn't a subwoofer.

Placement behind the couch for the MBM is recommended, as it provides more of a tactile effect...chest pounding mid-bass has more impact in a nearfield position.

Those same principles won't necessarily apply in your situation...as you're primarily having problems in the lower bass regions, and since your couch appears to be in the middle of the room, placing the sub directly behind your sub could actually be detrimental. That doesn't mean you shouldn't try it...just don't apply everything you're seeing in that thread as Gospel.

That being said, the folks at HSU are very knowledgeable when it comes to bass management. It wouldn't hurt to look around their subwoofer placement and set-up section to research and get ideas.

yepimonfire

i'm late here but have something important to add, polks subs are ported, ported speakers and subs have a tuning frequency and below the tuning frequency the driver will behave as if it is out of the box, which is bad. what happens is the subs tuning frequency is probably about 23hz or so and any lower content will actually cause the driver to be uncontrolled by the box and port volume allowing it to go over its excursion limit causing a wu-wump sound as the driver "snaps" violently. one way to figure out if this is what's happening or not is to play a 15hz sine wave at your normal listening volume. if this is indeed the problem then the only way to make it stop is to get a high pass filter that cuts off all LF below 20hz.

kuntasensei

yepimonfire wrote: »

i'm late here but have something important to add, polks subs are ported, ported speakers and subs have a tuning frequency and below the tuning frequency the driver will behave as if it is out of the box, which is bad. what happens is the subs tuning frequency is probably about 23hz or so and any lower content will actually cause the driver to be uncontrolled by the box and port volume allowing it to go over its excursion limit causing a wu-wump sound as the driver "snaps" violently. one way to figure out if this is what's happening or not is to play a 15hz sine wave at your normal listening volume. if this is indeed the problem then the only way to make it stop is to get a high pass filter that cuts off all LF below 20hz.

You would think that Polk would build in a filter to the amp to prevent port-unloading at the tune of their enclosure, especially with it being slot-loaded. If they don't, then that seems to be a serious design flaw considering these subs will be used for home theater (where the expectation is 20Hz and higher and most Blu-rays seem to troll that low lately). I think once he gets a high-pass filter in place near 25Hz, his issues will probably go away. Still, it's a shame that anyone has to go to that extent.

xxmastermushxx

Because that EQ check screen said FLAT. But then, I'm not familiar with the Denons, so I just assumed.

Did you not see the other one? I had pictures of both the EQ for Audyssey, and the EQ for FLAT.

The link you're referring to above relates to the HSU MBM-12....its a mid-bass module designed to play strongly in the 50-150hz range, and support both the subwoofer and the mains in the mid/upper bass regions. It behaves a little bit differently than a subwoofer, and given that it has a roll-off at 50hz, it technically isn't a subwoofer.

Yeah, I was looking at the HSU MBM-12 on their site. Wish I had the money for some of the subs HSU offers.

i'm late here but have something important to add, polks subs are ported, ported speakers and subs have a tuning frequency and below the tuning frequency the driver will behave as if it is out of the box, which is bad. what happens is the subs tuning frequency is probably about 23hz or so and any lower content will actually cause the driver to be uncontrolled by the box and port volume allowing it to go over its excursion limit causing a wu-wump sound as the driver "snaps" violently. one way to figure out if this is what's happening or not is to play a 15hz sine wave at your normal listening volume. if this is indeed the problem then the only way to make it stop is to get a high pass filter that cuts off all LF below 20hz.

Sine waves won't do it. It has to be a movie or something similar, the Db levels of sine waves just don't hit hard enough. I played a 100-5Hz sine wave at normal levels, no bottoming out, I can't even hear the 5hz unless I REALLY turn it up.

You would think that Polk would build in a filter to the amp to prevent port-unloading at the tune of their enclosure, especially with it being slot-loaded. If they don't, then that seems to be a serious design flaw considering these subs will be used for home theater (where the expectation is 20Hz and higher and most Blu-rays seem to troll that low lately). I think once he gets a high-pass filter in place near 25Hz, his issues will probably go away. Still, it's a shame that anyone has to go to that extent.

Would you recommend I still construct a High Pass Filter then? I'm not sure if I'll be able to put the sub in a near-field position. It sounds good with DynamicEQ off, at frequency such as fifteen and below the sub-woofer does bottom out a little.

Look at these, I've been researching bass shaking devices. They shake couches, chairs, and the like simulating the lower frequencies. You've probably heard of them, if you have what do you think? :cool:

http://www.amazon.com/Aura-Sound-T2B4-Bass-Shaker/dp/B0002ZPTBI

kuntasensei

I run a Buttkicker LFE with my SVS 20-39CS+ rig. They're great... but you'd still have to filter that 505 to prevent the port noise you're hearing. I think with a filter at around 25Hz, you'd free up enough headroom for that 505 to keep up nicely, and it should keep the driver from unloading.

xxmastermushxx

kuntasensei wrote: »

I run a Buttkicker LFE with my SVS 20-39CS+ rig. They're great... but you'd still have to filter that 505 to prevent the port noise you're hearing. I think with a filter at around 25Hz, you'd free up enough headroom for that 505 to keep up nicely, and it should keep the driver from unloading.

I plan to make a High Pass Filter then.

I was looking at the ButtKicker LFE, does it really go down to 5Hz, and give you the same feeling as a 5Hz capable subwoofer?

As you know, I can't afford $400 for a Buttkicker LFE starter kit. Would the Aura Pro Bass Shakers have the same affect, even if it is only rated at 20-80Hz. I could possibly afford two in the semi-near future.

Edit: Here's another type of transducer:http://www.amazon.com/Clark-Synthesis-TST209-Tactile-Transducer/dp/B002IFEGNC/ref=cm_cr_pr_sims_t

kuntasensei

In my experience, you need several of the Aura Pro or Clark Synthesis modules to do the same thing one Buttkicker does. Keep in mind that you have to buy an amp to power them as well. They're really not meant to replace a subwoofer though... They're meant to add to them. In my case, my SVS can handle down to 18Hz. The Buttkicker just adds that extra oomph to it, basically making my carpet-on-concrete floor feel like a floating wood floor because the couch vibrates the way it would on a wood floor. And honestly, I've got mine dialed back so most people wouldn't think there's a transducer unless I told them. They'd just think my subwoofer was freakin' awesome and could move the couch (which is can on its own, but...).

xxmastermushxx

kuntasensei wrote: »

In my experience, you need several of the Aura Pro or Clark Synthesis modules to do the same thing one Buttkicker does. Keep in mind that you have to buy an amp to power them as well. They're really not meant to replace a subwoofer though... They're meant to add to them. In my case, my SVS can handle down to 18Hz. The Buttkicker just adds that extra oomph to it, basically making my carpet-on-concrete floor feel like a floating wood floor because the couch vibrates the way it would on a wood floor. And honestly, I've got mine dialed back so most people wouldn't think there's a transducer unless I told them. They'd just think my subwoofer was freakin' awesome and could move the couch (which is can on its own, but...).

I wouldn't have it replace the PSW505, but if it can go down around 15Hz, it would be able to add some more oomph. I could use my dad's stereo amp, if I can persuade him, it has 100 watts RMS per channel. If not my dad's amp, would the sub's amp be able?

yepimonfire

yepimonfire wrote: »

i'm late here but have something important to add, polks subs are ported, ported speakers and subs have a tuning frequency and below the tuning frequency the driver will behave as if it is out of the box, which is bad. what happens is the subs tuning frequency is probably about 23hz or so and any lower content will actually cause the driver to be uncontrolled by the box and port volume allowing it to go over its excursion limit causing a wu-wump sound as the driver "snaps" violently. one way to figure out if this is what's happening or not is to play a 15hz sine wave at your normal listening volume. if this is indeed the problem then the only way to make it stop is to get a high pass filter that cuts off all LF below 20hz.

i wouldnt build a HP filter, below 20hz there are alot of harmonics that really affect the overall tone of the music, even your normal music and movies have harmonics as low as 4hz, the thing is they are usually -50dB of the volume like you musics fundamentals and louder harmonics are playing at 80dB and the harmonics at 30, which is a huge difference in volume. if its just WOTW i would ignore it.

kuntasensei

yepimonfire wrote: »

i wouldnt build a HP filter, below 20hz there are alot of harmonics that really affect the overall tone of the music, even your normal music and movies have harmonics as low as 4hz, the thing is they are usually -50dB of the volume like you musics fundamentals and louder harmonics are playing at 80dB and the harmonics at 30, which is a huge difference in volume. if its just WOTW i would ignore it.

Well, the issue here is that the 505's specs look like the port is tuned for about 23-25Hz. If that's the case, anything below that with significant energy could cause it to unload. A very mild filter around the tuning point of the sub would reduce that sub-25Hz energy, protect the driver, and probably get rid of the port unloading sound that he's hearing.

His only other option, assuming that placement doesn't solve his issues, is to get a better sub.

xxmastermushxx

yepimonfire wrote: »

i wouldnt build a HP filter, below 20hz there are alot of harmonics that really affect the overall tone of the music, even your normal music and movies have harmonics as low as 4hz, the thing is they are usually -50dB of the volume like you musics fundamentals and louder harmonics are playing at 80dB and the harmonics at 30, which is a huge difference in volume. if its just WOTW i would ignore it.

But if my sub can't play below 20Hz at -15Db on my receiver (66db) without distortion, why shouldn't I use a HPF? Please explain more thoroughly, I didn't quite understand your last post.

Edit: And it's not just WOTW.

yepimonfire

go into your receivers setup and reduce the volume of the LFE, not the sub, just the LFE. in the long run i would get a second identical sub. i still don't understand why it's unloading unless your running it hot, i'm using a PSW10 and i have yet to hand it more then it can carry. and it can play it, just not at a high volume. i also doubt -15dB on your receiver is 66dB, -15dB would mean during loud scenes your getting a 70w gain on a 100wpc receiver, that louder then 66dB, maybe 66dB during normal speech.

xxmastermushxx

yepimonfire wrote: »

go into your receivers setup and reduce the volume of the LFE, not the sub, just the LFE. in the long run i would get a second identical sub. i still don't understand why it's unloading unless your running it hot, i'm using a PSW10 and i have yet to hand it more then it can carry. and it can play it, just not at a high volume. i also doubt -15dB on your receiver is 66dB, -15dB would mean during loud scenes your getting a 70w gain on a 100wpc receiver, that louder then 66dB, maybe 66dB during normal speech.

I can't reduce the volume of the LFE, just the subwoofer its self. I don't want to limit that, this thread has already gone over all of that.

No, I'm not running my sub hot.

My receiver is a Denon AVR-590 it say's at -15Db it's 66db, I didn't really believe it either, I don't know.

This thread has also gone over buying another sub, not gonna happen.

yepimonfire

ah, well is WOTW the only thing you notice it on?

xxmastermushxx

yepimonfire wrote: »

ah, well is WOTW the only thing you notice it on?

No, but it shouldn't even be bottoming out on that. If the sub can't play 4hz content why let it?

yepimonfire

good point, perhaps the sub may be defective? if not, then like others have said i would say use a mild (like first order 6dB/octave high pass) this will allow you to retain a very mild amount of -20hz audio while keeping it at bay, on a first order that means all content an octave below 20hz will be 6dB less, a 4x power decrease, it will gradually roll off steeper as content goes lower so things like 10hz are -12dB, which is an 8x power decrease.

xxmastermushxx

yepimonfire wrote: »

good point, perhaps the sub may be defective? if not, then like others have said i would say use a mild (like first order 6dB/octave high pass) this will allow you to retain a very mild amount of -20hz audio while keeping it at bay, on a first order that means all content at 20hz will be 6dB less, a 4x power decrease, it will gradually roll off steeper as content goes lower so things like 15hz are -12dB, which is an 8x power decrease.

I highly doubt the SW's defective.

I'll probably go either 6dB /octave high pass, or 12dB/octave high pass. When budget allows get some Clark Synthesis modules for the real low ends.

yepimonfire

unless its an active high pass a 12dB low pass will eat gobs of amp power.