I recently tried an experiment by playing bass test tones though my system to test for room modes (for audio mixing setups). This was through Legacy Audio Aeris speakers and Wavelet (for room correction). The sound file includes sine waves from 24Hz up to 262Hz, increasing from bottom to top in one second increments. What I heard and felt was unexpected. The stereo bass did create a center phantom channel, and I could tell the bass comes from between the speakers. However, there are separate sound pressure waves, which felt very different. The sound pressure waves pressurized the room, causing all walls and ceiling to shake. It felt like my (20 ft by 16 ft) whole room was shaking apart. One thing that was interesting was that there was one frequency which seemed to be a create a null (where the sine wave was probably being cancelled out) where you don't hear the bass but hear the shaking of the walls and ceiling. The other thing that was interesting was that the volume wasn't set very high, so the volume itself didn't sound loud. If you want to hear bass, then take a listen to Yosi Horikawa's Wanderer album. The Wanderer track pushes the sub-woofers, really pressurizing the room. The feeling is very strange, as you can feel a bass wave flow up the floor through your sofa. It's like the node is moving towards you. Your ears also feel the pressurization rather than sound volume, a bit like when an airplane takes off, but your ears haven't equalized.

I am running large panel electrostats with dual subs (2.1 channel audio). I cross over the electrostats at a somewhat high 120hz. I then run L & R inputs into the subs with individual controllers so I can match level and crossover points, it works well. One song that makes stereo bass very apparent is "NWA - If It Aint Ruff"

Diffinetly want to hear that sealed vs ported sub video. Thanks guys for all the work, this was a great video. learned a lot

@PoesAcoustics

4 жыл бұрын

Sal S James said he is down. He plans to Chuck one of those SVS PB3000’s at my head.

Great video always your video turn my home theater experience to master piece

Love the thorough content.

Wow I have wondered about this for years. This is the first time hearing this.

@eduardopayton7776

2 жыл бұрын

I dont mean to be offtopic but does someone know a tool to log back into an Instagram account..? I somehow lost the login password. I would love any assistance you can give me

@andersjulius4610

2 жыл бұрын

@Eduardo Payton instablaster =)

A vote for true stereo subwoofer configuration. A thing that can't be avoided with mono is the phase cancellation that will occur at the signal level if the production contains stereo bass information, and that same problem will also occur with multiple subwoofers set up in mono. With a true stereo configuration (left/right signal to left/right subs respectively) you will get the "right" level of sub-bass every time as long as you are fine with the bass level set at the production stage. You will get stereo bass when the mix contains such information. You will avoid phase cancelations at the signal level that is meant to happen acoustically (which in turn can help create a more enveloping sound according to David Griesinger). And when the bass is already summed to mono at the production stage, it will be summed to mono acoustically anyway. There are some things to consider if home theatre, such as the LFE channel. But for stereo music.... It's a simple decision.

I'd been running dual subs in my room for some time. I had cheap subs and auditioned REL and SVS. I have since returned the better subs and bought bigger full range speakers instead. But in all cases, the subs/bass were front left and right. I had in fact been stacking my smaller tower speakers right on top of the subs. I tried running summed and stereo on the subs. I absolutely prefer stereo in this configuration. The lower frequencies will be mostly mono anyway. But even if you're crossing over at a lower frequency, you'll have energy up into frequencies you can localize, unless you're using a very steep slope on your crossover. Any built in analog solutions on your sub or stereo will tend to be 12db per octive, which isn't very steep at all. All that said, I had been stuck running my speakers in full range or high passing at 90hz on my Emotiva TA-1 that I had at the time. My cheap subs couldn't produce anything over 80hz and I didn't really notice any imaging issues, just a gap from the bass to mids.. The better subs could hit those "higher" frequencies and my stereo image degraded. Going stereo fixes the left right localization. That said, I could still tell too much that the subs were on the floor and the mids were coming out at eye level. This is why I bought Moabs instead. Moral of the story, stereo subs are good if they're near the front LR speakers, but getting your crossover point down to a reasonable level is more important. It still upsets me how few two channel systems offer any bass management at all, let alone a high pass for the mains and/or stereo subs.

Gene, it's your mic that's too quiet. You need to turn it up. I can barely hear you in my crappy car audio setup...

@Psyphonyx_Life

4 жыл бұрын

THIS ... and .. when I turn up to hear Gene ..and other voice comes in it's SOO DAMN LOUD.. omg.. compression ..or do some monitoring for the output.. this was bad.

@MaZEEZaM

4 жыл бұрын

Yes, I turned the volume up to hear Gene comfortably then ARGH my ears when Matt started talking...

hey Jean you should do a video on passive radiator subwoofers!

In most pop music, hip hop, and synthesised music you wouldn't notice. But in recording real instruments, it's not uncommon for something in the left channel to cancel out something in the right channel. Especially when you are recording something live. That could be a drum cancelling out a bass guitar, vocals cancelling out guitar, etc. It happens over the entire range, and it's usually accidental, but it's real. Consider a bass guitar that is panned left and a bass drum panned right play a similar frequency, but they are out of phase.. the sum of the two results in neither being all that audible, because they cancel eachother out. Rick Beato covers this phenomenon when using a mic for top and bottom skin of the same drum. If you don't invert the phase of one mic, the sum of the two mics results in them cancelling eachother. if you are aware of this, you account for it for X instrument. But it's difficult to determine that there's going to be a bass drum resonating at 101hz for a moment panned to one side, while a bass guitar is resonating at 103hz panned to the other side, and how that will sound when it's summed to mono. In stereo with full range monitors everything sounds fine, and then when the bass is summed into a mono sub suddenly that hit of the bass drum cancels out the guitar so both sound quieter. You almost never end up with a 180 phase shift between two instruments, but it's enough to notice.

Gene, a bit off the subject but still about subwoofers. I own a Sumiko S.5 sub that has a down firing woofer. It is on carpet. Would there be a sonic improvement if there were a plinth underneath it or would it make no difference? I see conflicting opinions on hifi forums. Thanks in advance!!!

The problem with stereo base is it sounds great when the recording has a stereo signal but when the base is all on the left side in you will not have a signal going to the right speaker.

@radiandrzgaming8708

Жыл бұрын

Fortunately, it's standard practice when mixing for the most part to place bass and kick in the center.

My left and right front speakers each have there own power sub woofer by using the electronic crossover in each power sub woofer,so the subs would be stereo (two channel).I have two more power sub woofers that just play the .1 low channel effect. The left and right surround share one power sub woofer.Bass type instruments have direction because of the higher frequency notes of the instruments. The back left and right speakers are full range.In playing moves I have a total of five power sub woofers running.All my speakers are JBL,none are small book shelf.

How do you set the phase on 4 subs placed in four corners of a rectangular room?!

How would stereo subs in the front corners, and two mono subs in the rear corners work out. I have my front LCR crossed over at 90hz. I am using two 12" subs crossed over at 90hz and 42hz (42hz per manufacturer's recommendation). My subs are 10db higher than my mains. Sounds great they match so perfectly...However, I am getting two 15" subs from the same manufacturer. These are recommended cross over set to 35hz. They are 14db higher than my mains. I really think this will work for me. The question...to set all to mono, all to stereo, or like I asked above. Also, should I cross these subs over the same as the rest of my system or, would it be better to set at 80hz?

Love all the informative videos. Question: setting up a livingroom that the wife wants to keep the room looking like a livingroom. What’s your opinion on the HSA line of subs. They are big but have really nice wood finishes. Thanks

@Bob-Fields

8 ай бұрын

Get rid of the wife. I did.

Yes ,Paul at PS audio is correct on how to hook up a subwoofer ,I show how to hook up a active subwoofer threw high input on my channel ,You get better phase matching and time alightment , I have been doing this for over 20 years for music , Back in the day we didn't have a subwoofer RCA output from our recievers and Integrated amps . Thanks for another Tech talk , awesome channel you have here

@Audioholics

4 жыл бұрын

for home theater this is usually NOT a good idea. You can get very good phase/timing using bass management in a sub/sat system if setup correctly.

@tee-jaythestereo-bargainph2120

4 жыл бұрын

@@Audioholics that's why i listed for music setup, i wasnt sure about home theater I knew the lfe is probly a must , thanks for the quick response ,Glad i found your channel . Awesome job on explaining power of amplifiers ratings on one of your previous videos thanks again !

@PoesAcoustics

4 жыл бұрын

Tee-Jay The Stereo-Bargin-File I also don’t really see why it would provide any better time alignment or phase matching (which are going to be related in this case). The problem with this approach is that it’s a lower quality and higher distortion means of signal transmission. In addition, it can risk reducing channel separation if the subwoofer hasn’t implemented the resistor pads in the high level input correctly. I’ve presented on time alignment of subs a number of times. It’s easy to measure and easy to fix. I do find that it’s commonly wrong in people’s systems, but I don’t see why the high level input would fix this. I’ve never understood this method myself, but I’ll admit having not tested it much. Maybe next time we are doing some sub testing outdoors we can bring a receiver and full range speaker and compare.

@tee-jaythestereo-bargainph2120

4 жыл бұрын

Just allows the front speakers and subwoofer to get the exact same signal From amp

i am not very experienced but i found out that a big number of voices, current reverb and balance can make a stereo sub and bass viable. The problem is phasing because low Hz is very long wave, u shall make it very clear and very balanced. Some sounds just not viable for it but i think that it is posiible and it makes the sound very deep and fulfilled if u have some time to work on it. And u have to check it on different monitoring devices

I just powered two Toby Lowman passive subs, I cut a hole in the sides and put the Jung SD 300 amp in each one , I use them as mono Right/ Left speakers. This is for HiFi listening.not home theatre…each of the amps are stereo, but I’m only plugging in to half of each amp.

Everybody all over the space for the audience needs to hear the bass whether stereo or mono. ✌🏾

So can you explain how I should set up my system if two of my subs are integrated into my towers, and my other two are independent?

@anandshah71

4 жыл бұрын

I would also like to know the same. I have a 2.2 active crossover system for music and movies how to make my existing Land R subs rumble in movies mode My music is great but movies I don’t get the crazy lows and rumble effect

Gene, run your audio through a program called Levelator to even out the levels of you and your guest. Cool video.

@Audioholics

4 жыл бұрын

Don't think you can do that for live streams but thanks.

Thank you for this. It basically put my mind at ease to whether this is worth it or not.

I got 2 subs . Set up diagonal. Svs sb4000 front left and sb3000 right rear. And running them front and back in the receiver seems to sound better than running them both mono. In mono my rear sub is too boomy. The rear sub is about 4 feet closer to me than the front sub. Not sure if I need to do something to the phase. That is set to normal on both .

If my sub is good up to 120Hz, should I still set crossover at 80Hz?

A pair of head phones with a mic would be a huge improvement! I have skipped a few videos because the volume is so low. I really like theses videos and want to hear every word.

@MaZEEZaM

4 жыл бұрын

or in this case its super unbalanced where one is WAY louder than the other which is worse in my opinion.

Matt, if it's about envelopment, have you tried Geddes' idea of decorrelating the subs with an external reverb box? Also, for most program is there a difference between "mono" and "stereo" subs? If the signal doesn't have bass phase or level variations, mixing the bass or not should not matter because it is the same anyway.

@PoesAcoustics

4 жыл бұрын

Raymond Cooke I know Geddes pretty well and I’ve never heard him talk about a reverb unit for bass before? Can you point to a reference so I can see what you are talking about? The simplest solution would be to have two subwoofers in either side of the listener with a drop ceiling. This setup absorbs the vertical mode entirely and maximizes the lateral separation. Logic 7 applies a 90 degree phase rotation to the low frequencies in one channel so that a 2 sub system has some left to right de-correlation. You can find reference to this in David’s website.

@raymondcooke5506

4 жыл бұрын

​@@PoesAcoustics here's one: www.diyaudio.com/forums/multi-way/200591-localizing-bass-7.html#post2785351

I was glad when Matt got a turn to speak.

In a room 17X 11, should both subs be in the front of the room or opposite corners?

@handroids1981

Жыл бұрын

If running two subs, then each sub should be in opposite corners. I.E. Front left and rear right.

Paul McGowan at PS Audio recommends using the speaker wire hookup (high inputs) instead of the LFE outputs for a stereo effect.

@Audioholics

4 жыл бұрын

Not the best idea for doing a home theater multi-ch setup with bass management and subwoofer level control.

@amazoidal

4 жыл бұрын

I think he was referring to stereo only.

@Audioholics

4 жыл бұрын

@@amazoidal yea that's ok for a 2CH setup IF you don't need to also bass manage your mains.

@dentman67

4 жыл бұрын

Do yourself a favor and discard at least 50% of everything you hear coming from Paul of PS Audio.

@russellborrego1689

4 жыл бұрын

@@Audioholics, you could always run the mains full range into the high level input on the subs and then active or passive high pass filter them at the mains, no? Or even simply use a passive two way that's crossed low and sending the low pass-high level to the sub and the high pass to the main, right? At least it seems right to me.

Iv got one stereo then a mono daisy chained to its amp best of both

Matt and Gene - which subwoofer do you have?

I have a hard time hearing you guys. I think your guests' microphone volume was more correctly set Gene. Thanks

@tims244

4 жыл бұрын

Maybe if they compressed the audio some more and boosted it with a limiter it would help, aswell as level matching it.

@bujoun76

4 жыл бұрын

I've actually skipped a couple of videos because the volume is so low.

@obudaifourty9

4 жыл бұрын

"Volume master" look for it :)

Ugh, Gene. Matt’s mic volume was fine. Your mic in the other hand... I have to turn up my volume way up to hear you. And because I am on max to hear you, naturally Matt is too loud.

I run buttckickers on both sides of my couch, with 2 separate amplifiers. When I tested bass music on both sides separately, I was extremely hard pressed to feel any difference on either of my sides since they're both connected to the same couch. The only big difference I felt was when they were playing the same thing simultaneously, they summed together and shook the couch 2x as hard. Looks like I'm better off with just mono bass.

Which subwoofer option will be more satisfying in a large open room with rf-7iii towers? PSA V18IPAL times 2 or one of the PSA flagship model TV36IPAL?

@Ctripp2448

4 жыл бұрын

Thomas riddell in a large open room you should go tv36ipal. Then your upgrade path will be cheaper. Then just add another tv36 down the road when funds are available.

@thomasriddell2893

4 жыл бұрын

@@Ctripp2448 I am pretty sure of my decision already but haven't pulled the trigger yet. I'm almost ready for the TV36IPAL!

@PoesAcoustics

4 жыл бұрын

Thomas riddell we can’t speak to specific subs like this. We addressed this on the video in a more general sense. If you take two identical subs and collocate then, expect to see 6dB of increased output. If you spread them apart, expect to see a more consistent response but with only 3dB of increased output. When the comparison is instead about one big sub or two smaller subs like this, things are less predictable. In any case, because a single sub is more prone to severe negative room interactions, you sometimes see more average output with two smaller subs spread around the room. This is a result of there being less deep nulls in the response. Having said all that, I love big subs. And if a sub ever overloads, it ruins the experience. It doesn’t matter if the average output is louder if at any individual frequency it is sufficiently low for you to distort it while using it.

@thomasriddell2893

4 жыл бұрын

@@PoesAcoustics I'm expecting the one large sub to give me a large goofy looking smile.

go dual or go home.... I personally have 2 different subs: 1 ported and 1 sealed, klipsch r-12sw and svs sb-2000, (which people suggest you shouldn't do) but after spending quite a bit of time configuring for my type of room it works like a charm. I set it up in a way where ported sub is supplementing the sealed one to give that higher output at 30 Hz and below where the sealed sub drops off drastically.

@ironmaiden5658

4 жыл бұрын

No, you are right. You shouldn't do that.. They should be identical. You are now running out of phase.. If you had two identical subs to compare what you have now, you would see it's not perfect at all.

@Weecka2007

4 жыл бұрын

@@ironmaiden5658 nope, it works fine, i had some testing done with REW and i'm having no problem. But it took me quite some time to set up, sort out the positioning and calibrating. It all depends on the room and i am not running out of phase, at least not what the testing shows. People keep saying you shouldn't do one or other thing, but there are so many variables in there: subs, positioning, setup, room size, room shape, furniture/items in the room... Saying something doesn't work without knowing the room setup is just WRONG!!!

@ironmaiden5658

4 жыл бұрын

@@Weecka2007 Its impossible to be working correctly I'm sorry to say. Its called physics. Sometimes we just like to convince ourselves and turn a blind eye. Your subs are moving at a different rate. Physics 101.

@ironmaiden5658

4 жыл бұрын

Weecka2007 You mentioned yourself that people suggest you shouldn’t do it. There’s a real reason why they say that, that you aren’t understanding. I’ve experimented with two different subs. Just to see for myself. That’s why I have two identical subs now.

@wa2368

4 жыл бұрын

GO EIGHT OR GO HOME. Ya never stop at 2 runt. You need 8....All those dips and nulls will be evened out sooo good. Start jumpin up and down when that cluster comes on.

I was going to run my front subs as right and left and use a down firing sub at about 4/5 back in the room. Now it sounds like that isn't going to work. If right and left isn't a thing at lower frequency then I'm thinking 1. My dream just died. 2. Hey Gene, would you like too make the greatest sounding movie ever made, this needs to be a thing. Example Die hard 4, in the tunnel a car hurtles over them from front to back. If it was done in front to back left to right it would be awesome. Talk to denon, can this be a thing and what about Atmos, dts x can they do that?

Besides the electronic channels & connections that can be varied, low frequency is not directional but this can have nothing to do with setups is why this subject should be considered. Major diff exists between acoustic/symphony vs electronic productions. VU meters can help with MIC gain.. reference.

in psychoacoustics, if you remove bass fundamental and just run higher harmonics, you can still hear bass, but since those are higher frequency you can localize bass so you can run mono subwoofer and still can hear the direction of the sound, though room pressure detection is kinda impossible even in stereo bass since the monoizing starts to happen around 80Hz.. well i am a simple DIY hobbyist from India, and i did my run on this experiment with 30 peoples and i think people can still hear stereo bass till 50Hz, if they are blind tested and are told to localize the bass note only :) 28 were able to tell stereo bass tone localization i didn't have bigger audience so i wont say that its confirm 50Hz also, the moment bass note comes with harmonic, its far easier to tell where the direction is And as always, thanks for your videos, long time viewer :)

Okay Gene!! You have some serious explaining to do. Can you please let us know, how a serious bass head like yourself, let Youthman get his hands on the Monoprice M215 sub before you...I've been watching your channel since Hugo and Butterworth were there, and this my friend does not compute. The audio and hometheater world needs the review of that sub/ product line from Audioholics!!

check your mic levels ,Gene raise up

All these comments about the audio, but what about the video? A lighting arrangement that makes Gene look a tad less sinister would be a nice touch. Love the discussions, but may have a little trouble getting to sleep tonight after this one...

Chorus is very common to add to bass guitar tracks.

Gene... try to get someone from Dirac to do a live interview on their new bass management module.

@Audioholics

4 жыл бұрын

Yes their new system sounds impressive.

I run both my powered subwoofers hi level, one hooked up to the left channel and the other to the right channel.

@tommyK7282

Жыл бұрын

But I run all my speakers set to large... I use EXT . STEREO settings on my pioneer elite with everything I play.

@tommyK7282

Жыл бұрын

I get no bass from dialog through my subwoofers.

Take your pick, ones too low or the others too high.

Did we understand right? Stereo bass doesn't help cancel out room modes?

@Audioholics

4 жыл бұрын

The only way to cancel or reduce room modes with subs is IF they are playing identical signals. Stereo bass is nonexistent in most mainstream music.

To have localized base the individual bass frequencies have to be programmed into the individual Channel in studio, practically no Studio does this.

@krane15

3 жыл бұрын

They don't do it because it doesn't matter. Humans can't localize those frequencies.

@stazorm1

3 жыл бұрын

@@krane15 I think we're arguing to different things

@krane15

3 жыл бұрын

@@stazorm1 "If a tree falls in the forest and nobody's there to hear it does it make a sound?" I don't think we are, since if you accept one, the other becomes inconsequential.

@stazorm1

3 жыл бұрын

@@krane15 Dey tuk our jerbs!!

@wadimek116

3 жыл бұрын

@@krane15 You still feel from which side bass is comming so its not that simple

Stereo bass can you compare white sound above 20khz. You can 't really hear but you are notesing it. And white the bass is a extra thing to mension, your body is listening not Only your ears.

@krane15

3 жыл бұрын

That's the only real point in adding more modules. Low frequencies aren't directional, but you can "feel" the additional sound waves/pressure. LFE more so than music.

Is james ok?

Such a shame you audio experts didn't expend any effort in balancing the sound volume of the two speakers.

I wish Gene's mic was better.

@Audioholics

4 жыл бұрын

Not the Mic, damn streaming software has no monitoring capability.

Strange to listen to video about audio and the audio on the video sux

Content is great but the volumes are just too unbalanced for me to listen to sorry :(

Gene, It sounds like you were in a null.

Bassiousness.

This whole topic seems like a big mix of contradiction. First of all, we are always told that the sub should disappear.. we should not be able to tell that the sound is coming from the subs.. but if you have a set of stereo Subs, wouldn't your theoretical purpose to be able to tell if it's coming from the left or right? Well, here comes another contradiction.. that means that the subwoofer crawl doesn't mean much at all in this situation. If you are running stereo subs and you find that the best place for your two subs are not symmetrical, then what is the point of running stereo? You would never place your left and right main speakers in different parts of the room for the "best sound" or you would lose your phantom channel. So which is it? You want to disappear? You want to be able to tell that the bass is coming from each of the left or the right? Or you want the best placement for your subs? How can you achieve all three when they contradict themselves? Sorry, this rant is not directed Audioholics - I have another situation going on and I had to vent lol. This video helped.

For Audioholics...the audio EQ between the mic volumes really sucks, pardon my French! To the point beyond listenable.

Gah damn let the man talk

Gene

so nobody should have an 18 inch sub for home theatre unless your have floor stand speakers that are 6 feet tall with dual passive 15 inch subs built in? lol

@krane15

3 жыл бұрын

You're just a bass addict. Admit it.

@MrJjburgess11

3 жыл бұрын

Some people just go nuts with their subs. I laugh when I see guys with book shelves then have 2 svs pb16s next to them . I would put that sub money into 2 nice towers first .

Gene, your voice is so soft while Matts fine. Pls get a better mic.

@Audioholics

4 жыл бұрын

The mic is fine. I switched to a Rode and didn't have time tonight to do a level check before going live.

@Audioholics

4 жыл бұрын

@@chandan6119 bring your tears here: patreon.com/audioholics

@Audioholics

4 жыл бұрын

@@chandan6119 i don't do videos for you nor do I care if you're a subscriber. Youthman and Technodad are good guys but you'll notice they don't live stream often or ever. I also never recall them offering the technical level of content we have on this channel. If you don't care for the quality of our broadcasts, don't watch. I owe you nothing. Remember that!

@barneyjones5174

4 жыл бұрын

@@Audioholics Gene,at CEDIA where your voice was strong you had the mic up to your mouth. Rode makes a nice boom arm if interested - www.rode.com/accessories/psa1

@Audioholics

4 жыл бұрын

@@chandan6119 funny how we still have MORE subscribers than every other major home theater focused YT channel, including the ones you mentioned. Let me know when you start your channel so I can come and bitch and wine about it too ;)

Dude ur mic

Can't even get the audio balanced on this video. FFS.

Gene's information was good, but the delivery was mundane.

@krane15

3 жыл бұрын

Then its a good think he wasn't telling jokes.

Gene's voice is way too low. Matt's voice is the proper volume.

Looks and sounds badly confused and misunderstood

Gene looks like he has little flames shooting out his nostrils. I think it's light reflecting off his specs but after I noticed it I couldn't shift my attention away from it.

actually Gene your volume is too low.

Considering the size of this channel, it's really the time now to invest into better camera and better mic. And some LED panel lighting. I love the content but at some point it's so painful really, so much video noise and so hard to distinguish what you are saying in so many interviews or videos. Get a xlr mic with proper interface like RME babyface.

@PoesAcoustics

4 жыл бұрын

The video noise is the camera. I’m working on a fix. My microphone setup is a lot better than you realize. It is an xlr mic. I have other mics. I wasn’t using a good interface which I can try. The problem is some of these streaming softwares don’t play nice with high end audio interfaces and fail to recognize all the inputs. I’ve had trouble. I have two LED lights on me. I actually need more lights. One reason for the exposure problem is just that the webcam can’t handle the dynamic range of a dark basement at night lit up like this. Also keep in mind they live streaming necessarily puts some limits on the bit rate of the codec we use. We are actively looking into options to improve this.

You can't even get your stereo balance right on the video!

@Audioholics

2 жыл бұрын

You can't even determine that there is no stereo balance in a mono recording in this video!

no, we can't

Audio on this video is awful. We're doing audio but can't set mics?

@Audioholics

Жыл бұрын

Check your hearing.