Hello, and welcome to Ask the Expert. My name is Christopher, and I'm your host. Today we're gonna talk about your room, the acoustics in it, and what you can do to improve your performance. And to help us out, we have a real expert here. Kristoffer, can you start by telling a little bit about yourself? - Yes, my name is Kristoffer and I'm an acoustic engineer here at Dynaudio and I work on a branch of different products. And you're going to talk about room acoustics today, and that's a fairly broad, difficult, super interesting topic. - So it's not something that we're gonna cover like really quickly? - No. - It's a long discussion. - It's a long discussion, and it's based on subjective opinions and objective means. - Well, if it's a long discussion I think that we should just jump straight into it and get started. - Yeah. - Kristoffer, our first question, that's from Domey, and Domey asked if you have a small room and you wanted a big hi-fi system in it, would that be a problem? - Yep, good question. Let me start with the room and not the speakers, because it's actually the room itself that is the problem, it's not the speakers. - Okay. - Whether you have a small room or if you have a big room you have the same set of problems, it's the same set of acoustic parameters in the room. We often talk about room modes as being the most prominent problem, it's in the bass region, and this is what you pick up when you move around the room. You can have suddenly a lot of bass, and other places in the room you have no base at all, and that's the same in a small room and it's the same in a big room. In the small room, these room modes are higher up in frequency, and they are spaced further apart. So if you have a room mode, let's say, at 60 hertz, then you have the second mode in that dimension at 120 hertz so every mode is spaced 60 hertz apart. In a bigger room you have a lower mode, so the first mode could be at 30 hertz then you have the second mode at 60 hertz, and 90 and so on, so you have 30 hertz spacing between each mode. - Okay. - Which in the end give you a more even frequency response in the low... - Because they're closer together. - Because they're closer together. So in the smaller room you have a more uneven, or you can have a more uneven frequency response in the room so that's actually a problem in the smaller room compared to the bigger room. - Okay. - So, if you put a small speaker or a big speaker in any of these room, you are going to excite these room modes given that the speaker can play low enough in frequency. - And you're talking about that, the room modes are higher in frequency in the smaller room, so even if you put smaller speakers into it that don't go as far down in frequency range, you're actually still going to excite them, right? - Yeah, because if you, depending on the room size, if let's say the first mode is at 60 hertz I guess all bookshelf small speakers today play at 60 hertz or even 40 hertz, so we are still going to excite these room modes whether you put a big speaker or a small speaker. - And have those problems. - And have the same problems. So it's not the speaker itself that is the problem it's actually the room. - Okay. - So you'll need to treat the room, and it's... - That's a whole different game right. - It's a different ball game, yeah, and it's not dependent on the speaker itself. - And I guess that's a different problem for the smaller room, right? Because you have, you are limited in space so you don't have room to put in bookshelves with a lot of books in the back and all that stuff. - Exactly, and if you wanna deal with the room modes, which is a low frequency mode, you need a bass trap or you'll need a panel absorber, you need something with a physical dimension that could be difficult to actually place in the smaller room. - Yeah. - Another problem with the smaller room compared to the big room, and this is, again, independent of the speaker size, is the actual placement of the speaker in the room and the stereo experience that the listener get, simply because you play around with the energy ratio between the direct sound from the loudspeaker and the reflected sounds. - Okay, and that's because the walls are close, or... - Exactly, yeah, so the distance between the listener position and the walls are shorter in the small room, which give you a different energy ratio and also a different timing ratio, so the timing between the direct sound and the reflective sound is different from the bigger room. - Okay. - And it might compromise the stereo listening experience. - So that would be the problem that the stereo image gets compromised because of the reflections off the walls? - It could be a problem, yes. - Okay, so if we are to sum up... - To sum up you can put in any size speaker in any size room... - And it'll work. - Yes. Depending on the room. - Depending on the room. Thank you. - Welcome. - Kristoffer, we actually suggested some topics that people could vote on and say, well, we really want to hear you talk about this, and the most popular one was actually what can I do to improve the acoustics in my room. So, is there anything I can do? - Yes, there is probably tons of ways you can treat your room, actually, and it's specific for the room. Any room has different problems. Some of the problems are more general as we have talked about earlier about the small room and the big room, they kind of share the same problems but at different frequency ranges. But all room has problems and to some extent all problems can be solved. But you need to look into the problem in your specific room, you need to target the problem correctly to treat it. - So there's no one thing you can do that solves everything. - No, no, but I read somewhere on the Internet that some people tend to say the more the merrier, so the more treatment you put in, now I'm talking about low frequency range so that could be bass traps. The more bass traps you put in, better. - Okay. - That's one way of looking at it. It might not solve all the problems, but it at least deals with some of the more prominent problems which are these low frequency room modes. Let's take an example. - Yeah. - Because this is becoming really general at the moment. Imagine you have a normal living room. - Yes. - It could be let's say four meters wide, six meters long, three meters high. That's a nice space for listening and living in. Bare walls, brick walls, concrete walls, something that is hard. You can easily imagine that a hard surface reflects a lot of sound, and it reflects, again, dependent a bit on the room size, low frequencies, mid frequencies, and high frequencies. So in that room without any treatment, any furniture or carpets or anything, you probably have a very long broadband reverberation. - Okay. - And reverberation is one problem, if you have too much reverberation in your room it smears the sound. - Yeah. - So you lose all the clarity, you lose the definition in your listening experience. - Okay. So that's one problem, reverberation. Reverberation in the mid frequencies and the high frequencies are fairly easy to deal with. - Okay. - Because we are talking high frequencies, that's the same as small wavelength and it's all the matter of wavelength versus the physical object you put in to solve the problem. - So the longer the wavelength is, the harder it is to solve? - Not necessarily, but you just need something that is physically bigger. - Okay. - It needs to be comparable to the wavelength. - So that's why bass traps are usually rather big. - Yeah. - Yeah. - And I'm talking in general terms here still. So the mid frequency and high frequency reverberation, you can deal with with the porous absorbers, foam that you put up, carpet, a couch can also help, even drapes at the back wall, for instance, can help minimize the reverberation or at least decrease the reverberation time broadband. But you also have in this fairly big room with these hard reflecting surfaces, you also have some reverberation issues at the low end. - Yeah. - To deal with reverberation we need to absorb the sound power in these frequency areas that you have the problem, so you need absorption, and that's just, as I said before, you can use porous materials like foam, furniture to absorb the high and mid frequency energy, but then you need the bass traps or panel absorbers to absorb the energy of the low frequency. - Okay. - So when we're talking reverberation time we are talking about absorption to lower the energy in the room. That's one thing. Another thing you need to treat in that room is your, or maybe you need to treat it. Again, it's becoming a bit subjectively here whether you like, for instance, to have a very prominent early reflection. - Okay. - So early reflection is the first reflection, so you have your speakers, listening position so we get the direct sound from the speakers then you have the first reflection either from the wall or the floor. - Okay. - Some people tend to have a very prominent first reflection because it helps to clarify the listening experience, to, for instance, place instruments in the room... - So you get a better stereo image. - Yeah. Some people prefer less prominent early reflections so you could put a carpet on the floor where you would have the first reflection. You could also put some damping or absorbers or diffusers on the walls that either just absorb the first reflection, then you're changing the ratio, the energy ratio between the direct sound and the first reflections. By using diffusers you keep the energy in the room but you scatter the energy, you make it less distinct, so to say. - Okay. - But you keep the reverberation time, the energy is intact. The spaciousness is different. - Okay. - Then we have, in rooms we have the room modes. A room mode is a reflection at a lower frequency. So in order to even out the frequency response in the low frequency, you need to deal with these room modes and the way to do it is actually to make sure there is no reflection, for instance from the back wall, that can be the tricky part. - Okay. - The bass traps is working as an absorber at low frequency, so it sucks out the energy so there is, the reflection has decreased, and when you decrease or minimize the reflection you don't have such a prominent room mode, and when you don't have the prominent room modes you even out the frequency response. - Okay. - Next up, there's a lot of topics to talk about here actually. - Yeah, because I'm starting to regret that I said that, is there just one thing I can do, because it sounds like there's a ton of things. - There's a plethora of things you can do. - Yeah. - You also have to look at modal ringing in your room. So if you, for instance if you measure your room and there's actually a quite nice freeware that you can use for measuring your room, the acoustics in your room. You can look at the, it's called decay time in the room versus frequency. So you do a measurement of your room and you get what is called a waterfall plot. - A waterfall plot? - Yeah, It's like a 3D plot so you have, on one axis you have frequency going from low frequency to high frequency and then you have a time axis as well. So what happens to your frequency response in time, and if you have these modal ringing in your room you will get these very prominent like peaks going in time sort of a resonant in your room. So your room has some resonance frequencies, where the room resonates longer than it does for other frequencies. - Okay. - For instance, in some rooms you talk about that the bass is sounding like a one note bass. All the bass you put in the room, even though the bass player's playing, it all sounds like the same note. - Okay. - That could be because you have this modal ringing in your room. So no matter what you play bass-wise in the room, you always excite these ringing or the resonances in the room. - So it's actually the room that makes it sound like one note? - Yes. - Okay. - And the speaker itself can also, if it's a poorly designed speaker it can do it the same. But it's often, most often it's the room that is actually giving it this one note feeling. And to deal with these modal ringing in your room, you also need bass traps. - Okay, so more bass traps. - More bass traps. Bass traps is a good thing. - So they better have a big room out there so they can fill in a lot of them, yeah. - Then you can also have a room that is too dead. It's overly treated, maybe you have soft walls, you have a insanely thick carpet on your floor, you have a lot of furniture. It's a soft room. It's not anechoic, but it's semi-anechoic so it's really becoming like this dense muffled room, and you need to live it up again a bit. And then you can put in deflectors or diffusers that scatter the sound around in there, actually giving it a bit more reverberance. - Or remove the really thick carpet. - Or remove the really thick carpet, yeah. So, every room has its own problem and you need to treat it individually... - And there's different solutions for each problem. - Yeah. - Yeah. - So yeah, unfortunately there's not like a, one solution to solve all problems. - No? - No. - But I guess that we've been talking rather generally with one specific case and obviously it's not everyone who's watching that has a four by six by three room. Is there anything, I know you were talking earlier about, before we started filming, about some resources online? - Yes, that's one of the good things about this problem is that it's widely accepted that the room acoustically has a lot of inherent problems, so there's a lot of nice resources on the website. - Okay. - I can mention, there's a page called realtraps.com which has a very pragmatic approach to how to measure your room using the freeware software and how to solve each problem. - Okay. So people can actually dive into their own specific case and start getting practical with these resources and try to solve some of the issues that they have? - Yeah. - Okay, and I know you're gonna give me a list that I can put in the show notes below the video, so you guys can just start watching even more video about this and hopefully solve some of the problems that you have in your rooms. Perfect. - Good. - We've been talking a little bit about room treatment in general and Nicholas actually posted a really good question in the comments, and he was wondering if you can talk a little bit about diffusion versus absorption, and some of the successes, the techniques, and failures with regard to that. - Yeah. Both diffusers and absorbers deal with reflections in your room. Absorbers decrease the energy in the room, so you're also lowering your reverberation time. - Yeah. - You can also decrease your modal ringing while diffusers keep the energy in the room, but scatters the reflections to make the reflections in the room less coherent. - Okay. - So that's kinda the summary of the two. - Pretty clear distinction between the two. - Yeah. - Yeah. So, how would you actually use, let's say, a diffuser in your room? - I think we need a case here to explain it better. So, everyone here has tried walking into a room, clap your hands... - I've done that, yeah. - And get an impression of the room. You get an impression of the reverberation time, is it a church or is it your living room, for instance? That's a very different distinction between these room just by clapping your hands. Sometimes you also notice these flutter echoes. - Yeah? - And that's a reflection that is going back and forward between two surfaces, and that flutter echo is a reflection in the room. And in order to treat that you could put in a diffuser. So when the reflection hits the diffuser, the reflection is scattered in the room and then you don't have the prominent reflection going back and forth. So you take the energy from the sound wave hitting the diffuser, but you spread the energy in the room. - So you lose the kind of ringing you get when they bounce back and forth from between the two walls? - Yeah. - Yeah. And when you clap, and I know we did it before we started to shoot this video, so, it's something everybody does, right? Is it every frequency range, is it the entire frequency range that you excite, or... - Nope. I don't know how low it goes in frequency, but it's the mid to the high frequencies you excite using the clap. So if you have a room mode, you don't excite the room mode if we're talking 40, 50, 60 hertz, you don't excite it using the clap. So if you wanna measure or get an impression of your low frequency problems in your room, then you need some measuring software that can actually play these... - The clap won't work. - The clap won't work. - No. - But it will give you an impression at least, but it doesn't fulfill... - The whole frequency range. - No. - I'm asking because it leads to a question that Santanu asked about bass diffusers, and obviously if it's for bass it's a bit lower in frequency, and if the clap only excites, you know, the mid to highs, you was talking about you have to do some real measurement to find out how the room actually performs in that frequency range. And if you do find out, what can you do about it with a bass diffuser? - The bass diffuser works similar as a mid to high frequency diffuser, but it needs to be bigger because we are talking low frequency so we're talking really long wavelength. Imagine 20 hertz, a full wavelength is 17 meters. - That's pretty long, that's a big room. - Yeah, that's a big room, but you don't need the 17 meters to deal with the problem. But just to give you an impression that we are talking like massive dimensions here, so the lower in frequency, the bigger the diffuser or the absorber for that matter. So, but the bass diffuser works in the same way as a mid to high frequency diffuser. It's about making the reflection less coherent in the room so it kind of scatters the energy around the room. You keep the energy, the low frequency energy is kept, but it's scattered in the room. You often find these bass diffusers in bigger recording studios, for instance, where you really need to know how is my room performing when I do the mix. Also, concert halls you have bass diffusers, maybe accidentally actually. Maybe the balcony, or the walls, or the seating... - Act like one. - Act like a, yeah. - Because I was thinking that you were talking about really big dimensions, so it's probably not something that you would have in a regular living room or listening room, Is it they're simply too big? - Yeah, and quite often in the normal listening space you would actually like to absorb the low frequency energy, you would like to decrease the reflection rather than just scatter it around for the low frequency. - Okay. - Yeah. - So, no bass diffusers, or rarely no bass diffusers in a normal living room, and diffusers for scattering the energy, absorbers for removing it. - Removing it, yeah. Yeah. - Good. Thanks! The next question, Kristoffer, is one of the topics that we suggested. It's, which frequencies are affected by walls and corners? - In theory, all frequencies are affected by the wall and the corner. - Okay. - It's just a matter of the material the wall and the corner's made of. So let's say it's a rigid corner, brick wall, all frequencies are reflected. - Yeah. With that said, in practical... - With that said, in practical set ups where we have a loudspeaker, the loudspeaker is not playing all frequencies in all directions. - Okay. - So the tweeter playing in the high frequencies is directional. - Yeah. - So it only plays sound in one direction. - Yeah. - This is the direction, this is the corner. - So, won't be affected. - It won't be affected the same way as the bass, because the bass is omnidirectional. It plays in all directions. So imagine you place your speaker in a corner, the tweeter plays in the listening direction and the bass plays in all directions. So the bass sound is reflected by your surface, and thrown back at you. - And what does that mean, what happens when the bass region is thrown back at you? - What happens at the listener position, so your experience will be more bass. - Okay. - But it's not just more bass, it can be over-exaggerated, boomy bass, so way too much bass, and you also, depending on the room and the speaker, you lose the tightness in the bass, it becomes blurred and way too much. So that's the problem, that's what happens when you take a speaker and put it in the corner. - And put into, yeah. And I guess that if we were to turn the speaker around and have the tweeter face the wall, it would still reflect even though it's directional because, well, it's facing... - Yeah, it's facing the wall, so the tweeter is reflected back at you. - But, if I wanted to actually try and solve the problem with the over-exaggerated, boomy bass, what would I do? - The easy solution, depending on the room size, is to take the speakers, move them away from the corner or the walls. - So that's pretty easy. Is there a kind of rule of thumb as to how far away from the wall? - Again, it depends on how low in frequency you would like to play. - Yeah. - So let's say your speaker plays down to 40 hertz. - Yeah. - A 40 hertz wavelength is around 10 meters. Half of that... - Half of it? - Is 5 meters, so in theory if you place the speakers 5 meters from the corner, you're good to go. - I guess that will be pretty difficult for most people. - That's pretty difficult. - Yeah. - So what would you, again in practical terms what would you recommend people do? - In normal conditions, and the rule of thumb is half to a full meter... - Okay. - From the wall and corner. - I think that's what most people can do. - Another solution to the problem, talking about the Contour series, we actually provide these foam plugs. - Okay. - And there's also a foam sleeve that you can put in the port which dampens the output of the port a bit. So even though you place it, let's say, not optimal in the corner or against a wall you can lower the low frequency output a bit. - Because the plug takes some of the energy out of the bass region? - Yes. - Yes. - Yeah. - So, if you can, move the speakers 50 centimeters to a meter away from the wall and that would take care of most... - Yes, yes. - Perfect. Kristoffer, one of the things that people wanted to hear us talk about is the RoomAdapt feature. It's a brand new feature that's in our music family of speakers, and I know that you actually designed it, so I think you're the perfect person to guide us through it and answer the simple question, what is RoomAdapt and how does it work? - Yeah. Just to clarify it, I designed part of it. - Okay. - As part of a team of course, in Dynaudio and in China, as well. RoomAdapt, it deals with the problem we are having when we put the speaker up against the wall or in the corner. - Yeah. - Where we get this over-exaggerated, boomy bass. So that's kinda the problem that RoomAdapt targets, and it's called Adapt because it is doing this adaptively. - Okay. - So if you as a user take the speaker and move it, the system automatically adapts to the new position in the room. - And I don't have to do anything about it, I just put it in a new place. - Yep, exactly. - Okay. - And it's simple, there's a built-in microphone. The microphone listens to the speaker, the system, it knows what it's playing, and it records what it gets in. In case you put it up against a corner, you have this power increase at low frequencies, this is registered by the system which then applies a set of filters to compensate for this. - Okay. So you're saying it compensates, are we basically just saying okay, you're in a corner now, so let's cut off some of the bass. - That's one way to put it, but it's not that simple, it's not just a simple high-pass filter where you cut off some bass. Dependent on the position relative to the corner, so the distance from the speaker to the corner or to the walls dictate a specific, let's say, call it a frequency response. You have some reflections that cancel each other out at that position, which gives some notches in your frequency response, and these notches and dips, peaks, have been modeled in the system and it's taken care of, so it's not just a simple high-pass filter, it's more like a complex high-pass filter. - And just for me to get this straight, is it some kind of settings that then are put into place when the microphone registers that, okay, I'm this close to the wall, or this far into the corner, or... - Yeah, we are working with, we call them zones. So whether, we have a wall zone, and when you're out of the zone it's called free field, no filters are applied. When you're in the zone, the wall zone, we apply the wall filters - Yeah... and we also have a corner zone. - That takes care of all of those frequencies that are getting messed up, so to speak. - Yeah, and it's only the low frequencies. As we talked about just before the low frequencies are omni-directional, so these are the primarily frequencies that are reflected by the walls and the corner, whereas the high frequencies, the mid to high frequencies are more directional. So the RoomAdapt changes the frequency response or the sound power of the system at low frequencies, up to around 500 hertz. - Okay. But, again, just for me to get this straight because I think it sounds pretty amazing that I can just as a user take my speaker and you said it adapts actively to wherever I put it. So I'm just gonna go and put it into the corner and then it just registers, because of the microphone sending out the music, the speaker sending out music and the microphone listening in, it automatically adapts to that corner, and if I have a party and I say okay, now I wanna move it into the middle of the room, I don't have to do anything, right, it just... - You don't have to do anything but moving the speaker into the middle of the room. - And it'll just figure out that now I'm here and I'm gonna adjust my settings? - Yeah, exactly. - That's pretty smart. - Yes, pretty smart. - So, yeah, don't have to do anything, not even press a button. - Nope. - Okay, well that's one way to take care of the room, I guess. - It's one way to deal with the speaker position in the room. - Okay. - So it doesn't fix any room related problems. If you have room modes in your room, you still have room modes, even though you use RoomAdapt. - And I guess that's where Adapt comes from. - Yeah, but you take care of the position of the speaker in the room. - So if, let's say that I do have a pair of music speakers at home and they're listening in, RoomAdapt is on, would it help to put in even more room treatment into the room? - If you have some problems, acoustical problems in your room before you put the music in there you still have the problems afterwards. - Okay. - So you should still deal with those problems. So, again, if you have some prominent room modes, low frequency room modes in your room, you need to treat those as room modes, and that's an acoustical treatment problem. - As we've just spent a lot of time... - As we just spent a lot of time discussing, yeah. - So to sum up RoomAdapt, I guess it's a automatic adaptive function that just makes sure that your music sounds the best possible way when you put it wherever you do. - Yeah, it's about clarity and definition in the low frequency region. And if you have this boomy, over-exaggerated bass because you put your speaker in a corner, then you lose the clarity, you lose the definition. By applying the RoomAdapt you can call it an EQ. You sort out your clarity again and your perception of the music just becomes clearer. - And you do it in a really easy way. - Super easy. - Perfect. Kristoffer, we're out of questions. So, there's only one thing left to do, and that's thank you for taking time out of your busy schedule to join us. - You're welcome. - And also, thank all of you not only for watching this long episode but for providing us with some really great topics to talk about. So, thanks, and see you next time.