Home room measurements

[tengiz]

By room measurements, I mean the characteristics of the room that are independent - or mostly independent - of the speakers.

Picture this: the room is already set up, furniture and all. I know where the speakers and listening spot will go. The goal is to preserve the layout and design first - then pick gear that fits.

So how do I measure the room in a way that helps me choose speakers that’ll actually work well in this specific setup?

We already have solid, measurement-based speaker rankings - directivity, off-axis response, and so on. But in-room response predictions still seem based on simplified models - maybe not a spherical room in a vacuum, but close enough.

They’re grounded in real data, sure, but how well do they handle real-world spaces? Most rooms are far from ideal - full of furniture, odd shapes, slanted ceilings, asymmetrical openings, random nooks. That’s what people are actually dealing with.

So is there anything that can take a real room, run some measurements, and suggest speakers likely to work well in that space?

It’s physically doable. The real question is whether a reasonably skilled DIY-er can pull it off without too much cost or hassle. I know one way to approach it - I’ve done something similar before, just not for room acoustics. But honestly, it’s probably overkill for this kind of use. You’d need specialized hardware and a pretty niche skill set to build it from scratch at home.

Just wondering if anything new has emerged on this front.

 

[DVDdoug]

Of course you need speakers and a microphone to measure a room. The mic can be calibrated but as far as I know there is no calibrated speaker and if there is you probably can't get your hands on it.

and suggest speakers likely to work well in that space?

A better speaker almost always works better than an inferior speaker in any room

 

[Holmz]

…
They’re grounded in real data, sure, but how well do they handle real-world spaces? Most rooms are far from ideal - full of furniture, odd shapes, slanted ceilings, asymmetrical openings, random nooks. That’s what people are actually dealing with.
…

Most of the stuff in a room helps.

 

[tengiz]

Most of the stuff in a room helps.

Right. But it's not always the case.

A better speaker almost always works better than an inferior speaker in any room

One thing I’ve noticed - totally expected, of course - while experimenting with different speakers: woofers or ports at different heights, orientations, etc. can excite different room modes, which may noticeably affect the room response in the modal range at the listening position. That alone can be a deciding factor between speakers that look nearly identical based on Spinorama data.

 

[Holmz]

Right. But it's not always the case.


One thing I’ve noticed - totally expected, of course - while experimenting with different speakers: woofers or ports at different heights, orientations, etc. can excite different room modes, which may noticeably affect the room response in the modal range at the listening position. That alone can be a deciding factor between speakers that look nearly identical based on Spinorama data.

Bookshelves, plants, sofas, people etc., all tend to help the room acoustics.

 

[witwald]

By room measurements, I mean the characteristics of the room that are independent - or mostly independent - of the speakers.

Picture this: the room is already set up, furniture and all. I know where the speakers and listening spot will go. The goal is to preserve the layout and design first - then pick gear that fits.

So how do I measure the room in a way that helps me choose speakers that’ll actually work well in this specific setup?

@tengiz Can you please provide an annotated diagram of your room and its layout? Ideally in 3D, but a 2D layout would be much better than nothing. At the moment, we are all flying blind here, so to speak, except of course for you. The more information that you can provide, the better, as it always helps.

 

[witwald]

One thing I’ve noticed - totally expected, of course - while experimenting with different speakers: woofers or ports at different heights, orientations, etc. can excite different room modes, which may noticeably affect the room response in the modal range at the listening position. That alone can be a deciding factor between speakers that look nearly identical based on Spinorama data.

With respect to the last sentence, I'm not really sure why that would be the case, as the Spinorama data tacitly embodies all of the interactions between the different radiating surfaces. Maybe you can explain further?

 

[tengiz]

Bookshelves, plants, sofas, people etc., all tend to help the room acoustics.

Sure, but rooms can also have floor-to-ceiling hardwood panels, large glass windows, brick walls, etc. - in other words, large reflective surfaces that no amount of furniture or other objects can offset easily. I have a room like that in my house. In the picture here I experimented with KEF R5 Meta, I wanted to see if one of the best speakers according to Spinorama would perform well. They didn't.

There’s a brick wall opposite the window in the center, and a wide opening on the right, just outside the frame. I’ve got in-ceiling speakers in this room - old 2-way Parasounds. Overall, even they actually sound better than the KEFs - despite the KEFs, as expected, produced much better imaging, it was totally out of balance, because the reflections/reverb don’t match the imaging at all.

 

[tengiz]

Can you please provide an annotated diagram of your room and its layout? Ideally in 3D, but a 2D layout would be much better than nothing. At the moment, we are all flying blind here, so to speak, except of course for you. The more information that you can provide, the better, as it always helps.

See my previous post for some basic info about the room - I only used it to illustrate a point. Just to clarify, it’s not my dedicated listening room.

My actual media room was designed and built as such when the house was constructed. I spent a lot of time and effort making sure it had proper acoustic treatment. It works well, and basically any reasonable speaker I’ve tried in there has also worked well after EQ-ing the modal range.

With respect to the last sentence, I'm not really sure why that would be the case, as the Spinorama data tacitly embodies all of the interactions between the different radiating surfaces. Maybe you can explain further?

I’ve noticed that the KEF R5 Meta and Martin Logan Vista or Ethos produce different frequency responses in the modal region. The difference isn’t huge, but it’s very consistent. Since I measure all the speakers in the exact same locations, my guess is that it has to do with woofer height. The KEF’s woofers are around 1.7' and 3' off the floor, while the Martin Logans place theirs basically right at floor level.

Thank you.

 

[tengiz]

This is Vista (red trace) and KEF (blue trace - clearly very different shape of the response between 80 and 200Hz.

And this is the Vista and Ethos (yellow trace) - they basically match up to 300Hz. The difference in overall level is due to the Ethos having a powered woofer, and the slope below 100 Hz comes from the low-frequency gain being set to -10 dB during the measurement.

 

[Holmz]

Sure, but rooms can also have floor-to-ceiling hardwood panels, large glass windows, brick walls, etc. - in other words, large reflective surfaces that no amount of furniture or other objects can offset easily. I have a room like that in my house. In the picture here I experimented with KEF R5 Meta, I wanted to see if one of the best speakers according to Spinorama would perform well. They didn't.

View attachment 466299

There’s a brick wall opposite the window in the center, and a wide opening on the right, just outside the frame. I’ve got in-ceiling speakers in this room - old 2-way Parasounds. Overall, even they actually sound better than the KEFs - despite the KEFs, as expected, produced much better imaging, it was totally out of balance, because the reflections/reverb don’t match the imaging at all.

Great - is that your room then?

 

[tengiz]

Great - is that your room then?

Yes, one of them. But it clearly is not suitable for listening with decent fidelity when paired with otherwise fantastic floorstanding speakers with dynamic transducers.

 

[Keith_W]

Your room is gorgeous!

Anyway, to answer your question - about the only characteristic of the room that can be measured independently of speakers is the noise floor, and even that changes depending on ambient noise. The RT60 and other reverb measurements are only interpretable at high frequencies. Anything below a certain frequency is specific to the location of the microphone and speakers and thus have poor repeatability. The pattern of room modes will remain the same for any speakers/subs in the same location and microphone position, but the specifics will change depending on speakers and especially with DSP.

Anyway, you appear to have a speaker with normal directivity (KEF) and narrow directivity (Martin Logan). In your opinion, which speakers work better for you in your room?

 

[DanielT]

Sure, but rooms can also have floor-to-ceiling hardwood panels, large glass windows, brick walls, etc. - in other words, large reflective surfaces that no amount of furniture or other objects can offset easily. I have a room like that in my house. In the picture here I experimented with KEF R5 Meta, I wanted to see if one of the best speakers according to Spinorama would perform well. They didn't.

View attachment 466299

There’s a brick wall opposite the window in the center, and a wide opening on the right, just outside the frame. I’ve got in-ceiling speakers in this room - old 2-way Parasounds. Overall, even they actually sound better than the KEFs - despite the KEFs, as expected, produced much better imaging, it was totally out of balance, because the reflections/reverb don’t match the imaging at all.

Nice room and view. I don't really understand regarding your picture. Where is your listening position? On one of the sofas? The KEF R5 Meta speakers where they are placed now, how are they directed? Towards the large window (I'm guessing that's not the case but it's hard to tell from the picture) or with the back of them towards that window?

Where do you have the in-wall speakers, which you like the sound from, placed and directed towards?

Have you tried squeezing the speakers into the corners, there by the wall by the big window? Pros and cons, sound-wise, of doing that, but you can still test it while you're at it. You like sound from speakers mounted into the wall, so who knows if it would appeal to you with speakers placed in the corners.
I have tested corner placed speakers myself. Advantage bass headroom for EQ but a very annoying disadvantage of being able to localize the sound coming from the speakers. It is the worst sound I know when that happens, so no corner speakers for me. BUT those were my experiences in my room. Doesn't have to be that way for you.

Have you tried fixing that peak at about 70 Hz? I had a similar one at 80 Hz. I filed it down via EQ and the sound became much better. Such an operation would possibly, probably, make it easier to concentrate on your other challenges. Than hearing the annoying bass peak, that is.

 

[DanielT]

My actual media room was designed and built as such when the house was constructed. I spent a lot of time and effort making sure it had proper acoustic treatment. It works well, and basically any reasonable speaker I’ve tried in there has also worked well after EQ-ing the modal range.

Aha, so you have EQ, but it was in another room. Okay then we don't need to talk about EQ and its benefits and so on because you have that part covered.

 

[Holmz]

Yes, one of them. But it clearly is not suitable for listening with decent fidelity when paired with otherwise fantastic floorstanding speakers with dynamic transducers.

I’d chuck a couple plants in there.

 

[tengiz]

Your room is gorgeous!

Anyway, to answer your question - about the only characteristic of the room that can be measured independently of speakers is the noise floor, and even that changes depending on ambient noise. The RT60 and other reverb measurements are only interpretable at high frequencies. Anything below a certain frequency is specific to the location of the microphone and speakers and thus have poor repeatability. The pattern of room modes will remain the same for any speakers/subs in the same location and microphone position, but the specifics will change depending on speakers and especially with DSP.

Anyway, you appear to have a speaker with normal directivity (KEF) and narrow directivity (Martin Logan). In your opinion, which speakers work better for you in your room?

RT60 - doesn’t it also depend on the speakers as well? I mean, at the very least, the directivity should have some effect, especially if the walls, ceiling, and floor have significantly different/variable absorption or reflection properties. I could imagine a measurement that, for specific locations of the future speakers and the listening spot, would capture the characteristics of the room that are complementary to the directivity of the speakers - the directivity of the room, if you will - and then try to predict which speaker directivity pattern would work better.

About the repeatability of the low-frequency response - doesn’t the same go for speakers? I mean, you can take an otherwise perfect speaker with a flat anechoic response, place it in a real room, and that flatness is just gone in the modal region. Still, we value those speaker measurements.

The answer to your question is easy - narrow directivity does win hands down in this room, as I’m sure you’d expect. But it still doesn’t sound good. Yes, the view is great, and I really wanted to have a second listening location in the house in this room. But alas, it just doesn’t work for that purpose.

 

[tengiz]

Nice room and view. I don't really understand regarding your picture. Where is your listening position? On one of the sofas? The KEF R5 Meta speakers where they are placed now, how are they directed? Towards the large window (I'm guessing that's not the case but it's hard to tell from the picture) or with the back of them towards that window?

Where do you have the in-wall speakers, which you like the sound from, placed and directed towards?

Have you tried squeezing the speakers into the corners, there by the wall by the big window? Pros and cons, sound-wise, of doing that, but you can still test it while you're at it. You like sound from speakers mounted into the wall, so who knows if it would appeal to you with speakers placed in the corners.
I have tested corner placed speakers myself. Advantage bass headroom for EQ but a very annoying disadvantage of being able to localize the sound coming from the speakers. It is the worst sound I know when that happens, so no corner speakers for me. BUT those were my experiences in my room. Doesn't have to be that way for you.

Have you tried fixing that peak at about 70 Hz? I had a similar one at 80 Hz. I filed it down via EQ and the sound became much better. Such an operation would possibly, probably, make it easier to concentrate on your other challenges. Than hearing the annoying bass peak, that is.

The "listening position" during this exercise was roughly where the picture was taken from. And again, just to underscore it - I gave up on using this room for quality listening years ago. The location of the windows and the orientation of the house more or less dictate where the listening position should be visually or aesthetically, which means there’s no way to fix the strong first reflections without acoustic treatment.

Applying any acoustic treatment to wooden panels? That was a no-go for me

Her's the picture of the in-celinig speakers:

As I said - it’s an old 2-way Parasound pair. They don’t produce spectacular imaging or particularly impressive frequency response, but they sound balanced. There’s no disconnect between the imaging and the reverb or reflections.

 

[DanielT]

The "listening position" during this exercise was roughly where the picture was taken from. And again, just to underscore it - I gave up on using this room for quality listening years ago. The location of the windows and the orientation of the house more or less dictate where the listening position should be visually or aesthetically, which means there’s no way to fix the strong first reflections without acoustic treatment.

Applying any acoustic treatment to wooden panels? That was a no-go for me

Her's the picture of the in-celinig speakers:
View attachment 466388

As I said - it’s an old 2-way Parasound pair. They don’t produce spectacular imaging or particularly impressive frequency response, but they sound balanced. There’s no disconnect between the imaging and the reverb or reflections.

What do you think about replacing the old 2-way Parasounds with some better in-celinig speakers?

If it can be done without too many mounting problems?

 

[tengiz]

What do you think about replacing the old 2-way Parasounds with some better in-celinig speakers?

If it can be done without too many mounting problems?

There’s easy access to the attic above this room. It’s unfinished, and there’s no floor directly above the speakers, so they’re actually pretty straightforward to replace - they’re fully exposed from above. There’s also plenty of space to install larger speakers if needed. I’ve spent some time looking into possible replacements, but the real question is how to choose speakers that would actually work well in this room and in that particular ceiling location. I know KEF makes architectural models with their coaxial drivers, but would it even make sense to install something that advanced so close to the corners? Plus, the ones that I looked at are not sealed, so they assume the enclosure created by the in-wall installation. This is not my case - I would need to add some box or something.

Edit: I mean, this is one of those cases where you really do want to have a pretty good idea before cutting into walls or the ceiling - unlike floor-standing speakers, which you can just move on from if they don’t work out.