WIDE OPEN ROOM ENTRANCE - Consequences for bass frequencies etc? (PHOTOS within)

[MattHooper]

Hey folks,

I'd like to use my listening room for a question about acoustics.

Back in around 2009 or so I did a total reno of our living room turning it in to a dual-use Home Theater and 2 channel listening room. It wasn't an easy sell for my wife as it's the very first room you see from the hallway when entering the house, but she came around and enjoyed the results too.

I made the goal maniacally difficult by insisting the room work well for a home theater and my separate 2 channel system. So there are separate home theater speakers, stand mounted monitors L/R, a very large Center channel, and surround speakers etc.

I used to have my speakers toward the bay window side of the room, with the listening sofa opposite against what is now my projection screen wall. Having to flip the seating and 2 channel speakers 180 degrees provided some challenges, not the least that it put some more restrictions on placement of the 2 channel speakers, as they now threatened to block passage in and out of the entrance-way. Fortunately, the narrow range of placement (distance to listening sofa) that allows easy passage in and out has also been excellent for great sound.

Part of what makes the room sound excellent is that it was renoed with the input of an acoustician, so there are various strategic placements (most hidden) of acoustic treatment.

BUT...and this is the main point of the post....as you can see there is a significant open entrance area to the hallway, near the Right speaker.
The room is 13 feet wide by 15 feet deep (15 feet from the center of the screen wall to the bay window behind the listening sofa). The room opening
is 5 1/2 feet wide.

My question is: what are the likely sonic consequences for bass frequencies (or any other frequencies) in this set up, given that room opening?

How much might this room opening account for the fact I seem to get, at least subjectively, mostly smooth sound down in to the bass frequencies for any speaker I've tried in those positions, large and small?

Apparently room acoustics are pretty predictable when you are dealing with, say, a standard rectangular, closed room. They get harder to predict when you add things like those angled bay windows behind the listening sofa. They get harder to predict still (I believe) when you have a big room opening like that as well.

One reason I ask is that in all the talk of "fitting the speaker to the room" - e.g. not putting a full range floor standing speaker in a room that is too small and overloading the bass frequencies etc - it's hard to know if, in practice, I should consider my room a "small to medium sized room" or if it is in effect a "big room" in terms of what the bass frequencies see in regards to that room opening giving those frequencies "more room to breath" as it were.

I certainly did have conversations about this with the acoustician, but that was 13 years ago, hard to remember his exact replies, but I do remember he said the room opening had a significant influence.

Please weigh in with any wisdom on this subject. Thanks.

(Photos supplied are some original plan drawings, and then a few photos I snapped today :

 

[Doodski]

Lovely room. Is that a heritage house? In my experience the entrance opening will change the frequency response of the speaker. Subjectively I've noticed variations from left to right in this sort of layout. I try to keep the openings behind me when I am facing the speakers.

 

[MattHooper]

Lovely room. Is that a heritage house? In my experience the entrance opening will change the frequency response of the speaker. Subjectively I've noticed variations from left to right in this sort of layout. I try to keep the openings behind me when I am facing the speakers.

Thanks. I believe it was built around 1911 - 1920ish. I'm not sure if that meets the "heritage" designation. But certainly all the old original wood was an attraction.

As for variations from left to right, if I understand, you'd mean some sort of noticeable imbalance to the sound?

That's actually been one of the curious and surprising aspects of the performance, given one speaker is nearer the hallway AND very close to the edge of the sofa. Yet there is no imbalance that I can detect whatsoever, either in imaging or in the frequencies (e.g. bass seems even from both speakers, very well centered etc). I am able to manipulate the reflectivity of the higher frequences to a degree. I have a thick velvet cover I put over the reflective fireplace near the left speaker, when listening to music, and there is a curtain made of the same thick velvet by the wall of the right speaker, which I can use to "dial in" the reflectivity on that channel. I end up with subjectively very even sound in the upper frequencies this way. (For instance, certain tracks where an instrument or voice is panned to move from the left through to the right speaker, sounds consistant as it moves between each speaker).

 

[Soniclife]

They get harder to predict when you add things like those angled bay windows behind the listening sofa. They get harder to predict still (I believe) when you have a big room opening like that as well.

Fortunately we don't need to guess these days, we can measure.

Big room and small room speakers are concepts from the past, use EQ, it's a huge improvement at the bottom end.

 

[MattHooper]

Fortunately we don't need to guess these days, we can measure.

Big room and small room speakers are concepts from the past, use EQ, it's a huge improvement at the bottom end.

Thanks, I'm aware of that, and as I've said I'm quite happy with the sound as it is. No EQ desired. (And I did actually use room EQ when I had subwoofers for a while...didn't really sound significantly better IMO). Since I'm not going to, for instance, do a measured A/B comparison by installing and removing a temporary wall at my room entrance, I was more curious. I presume nobody can do accurate calculations based only on the room images I've supplied, so I am looking for just some general insights on the issue, some general inferences.

 

[Doodski]

Thanks. I believe it was built around 1911 - 1920ish. I'm not sure if that meets the "heritage" designation. But certainly all the old original wood was an attraction.

In Canada that would be a heritage home if one applied for status but that means it has to be kept up and that means it's resale may be tricky but not impossible; peeps are looking for such things here and they buy when they find them. I've lived in a 3 story 1886 heritage home with bay windows everywhere, a huge fireplace and large rooms with tall ceilings and it was wonderful.

As for variations from left to right, if I understand, you'd mean some sort of noticeable imbalance to the sound?

Yes, a imbalance.

That's actually been one of the curious and surprising aspects of the performance, given one speaker is nearer the hallway AND very close to the edge of the sofa. Yet there is no imbalance that I can detect whatsoever, either in imaging or in the frequencies (e.g. bass seems even from both speakers, very well centered etc). I am able to manipulate the reflectivity of the higher frequences to a degree. I have a thick velvet cover I put over the reflective fireplace near the left speaker, when listening to music, and there is a curtain made of the same thick velvet by the wall of the right speaker, which I can use to "dial in" the reflectivity on that channel. I end up with subjectively very even sound in the upper frequencies this way.

I was thinking more of the horn effect where the bass would be more prominent on one channel. One can stand in the corner and speak and hear a difference and then even face the corner and speak to get a rough idea if the acoustics vary from side to side. It can be obvious using this test method.

 

[Kvalsvoll]

My question is: what are the likely sonic consequences for bass frequencies (or any other frequencies) in this set up, given that room opening?

This opening is small enough that it is not likely to cause any problems for low frequencies.

Large open spaces, L-shaped rooms, rooms with very large openings into other rooms, often cause problems for bass due to reflected low frequency energy from the connected space. But if the opening into that space is smaller than the size of the wall, this effect is reduced.

The boundary conditions of L and R speaker will be very different, due to the missing wall section close to R speaker, but that is not a huge problem today, with speakers with controlled directivity.

The problem I see here is more practical, the speaker can not be placed so it obstructs the entrance to the room, this will limit placement options, so you may not be able to place L R speakers where you want them for best sound.

 

[MattHooper]

This opening is small enough that it is not likely to cause any problems for low frequencies.

Good. I was just as curious if there were benefits to the opening as well (e.g. stopping the bass frequencies from too much boundary effects, e.g. if the room were sealed).

Large open spaces, L-shaped rooms, rooms with very large openings into other rooms, often cause problems for bass due to reflected low frequency energy from the connected space. But if the opening into that space is smaller than the size of the wall, this effect is reduced.

The boundary conditions of L and R speaker will be very different, due to the missing wall section close to R speaker, but that is not a huge problem today, with speakers with controlled directivity.

I'm not having any noticeable issues at any frequencies, so seem to be good there. Still especially curious about the effects in the upper to lower bass frequencies - whether the room opening as it is would provide a challenge...or instead possibly mitigate some issues that might have occurred if there wasn't a room opening.

The problem I see here is more practical, the speaker can not be placed so it obstructs the entrance to the room, this will limit placement options, so you may not be able to place L R speakers where you want them for best sound.

Yes that was my original concern in re-doing the room. But as I mentioned it worked out great. I sit at the same distance I've always preferred for my speakers, but I can also pull them out further from the rear wall than I used to. The results have been the best sound I've ever had in my room (though Thiel 2.7 speakers are pictured, I've use a variety of speakers from larger Thiels, to MBL omnis, to Joseph Audio floor standing speakers and others).

 

[GD Fan]

Is the front right speaker basically up against the sectional or is that a photo illusion?

 

[MattHooper]

Is the front right speaker basically up against the sectional or is that a photo illusion?

No illusion. The right speaker is inches from the chaise end of the sofa, just as it looks in the second photo of my room.

If the grill was off you'd see the 8" woofer is above the line of the sofa firing "over" the sofa, the passive radiator below. I was surprised that there wasn't any noticable detriment to the sound (bass especially) in that position. Perhaps it speaks to the more omni-directional nature of bass frequencies (?). And perhaps the absorbant nature of the large sofa. Bass sounds super even, balanced and well focused, generally.

 

[Kvalsvoll]

Good. I was just as curious if there were benefits to the opening as well (e.g. stopping the bass frequencies from too much boundary effects, e.g. if the room were sealed).

There is a benefit in that it acts like a nearly perfect absorber, with size equal to the size of the opening.

Nearly perfect because it will radiate the reflected energy from the other room, but this sound will be reduced in level and delayed, so there are no early reflected energy from this.

If there is no annoying left-right shift in the soundstage, there is no problem.

 

[JRS]

I've owned a variety of well regarded speakers in a number of listening situations that range from very open to your typical parallelopiped (waiting for decades to use that word) and absolutely w/o a doubt prefer irregular rooms with large openings. If the floor plan is extremely open subwoofers seem darn near de riguer, but always figured that it spread out the nodes. Bear in mind that most of this experience was without much DRC, just PEQ to tame the big resonances, so I cant rule out that great bass can be achieved in a uniform space, but when looking for new digs, always looking for a situation where the back wall is absent or has big clhunks missing. I also like high ceilings so maybe it's taste for a visually open environment that is at play.

Beautiful home btw.

 

[Hipper]

Firstly I will say that if you like what you've got then that's the most important thing.

My experience though is that we think our sound is good but you soon find out it can be better. You find this by getting advice and then experimenting. You are asking for advice but you have to be aware that much advice will be based on doing things that you may not be able to do.

The ideal situation, a dedicated listening room, allows you to do the following:

1. Move the speakers and listening chair anywhere in the room.
2. Add room treatment (bass traps etc.).
3. Use DSP/EQ.
4. Use subwoofers.

You could use any or all of these, the more flexibility the better.

The first step in all this ideally will be to measure. Measuring is not perfect and should be used as a guide but it is more consistent then just listening.

As my Mum used to keep telling me (and I probably didn't take much notice!), if a job's worth doing it's worth doing well.

Your problem is of course that you have a lovely looking room and don't want to spoil it. Do you know what sort of treatment your acoustician incorporated in the room?

If you don't want to measure with a microphone you could get a test CD and just listen. There are two I'd suggest:

https://realtraps.com/test-cd.htm

This will tell you how your bass is doing.

https://www.discogs.com/release/9922972-Various-Gold-Stereo-And-Surround-Sound-Set-Up-Disc

I don't know if this is available anymore but it has channel balance tests amongst others.

There may be more modern ones that I'm not aware of.

 

[MattHooper]

Firstly I will say that if you like what you've got then that's the most important thing.

My experience though is that we think our sound is good but you soon find out it can be better. You find this by getting advice and then experimenting. You are asking for advice but you have to be aware that much advice will be based on doing things that you may not be able to do.

The ideal situation, a dedicated listening room, allows you to do the following:

1. Move the speakers and listening chair anywhere in the room.
2. Add room treatment (bass traps etc.).
3. Use DSP/EQ.
4. Use subwoofers.

You could use any or all of these, the more flexibility the better.

The first step in all this ideally will be to measure. Measuring is not perfect and should be used as a guide but it is more consistent then just listening.

As my Mum used to keep telling me (and I probably didn't take much notice!), if a job's worth doing it's worth doing well.

Your problem is of course that you have a lovely looking room and don't want to spoil it. Do you know what sort of treatment your acoustician incorporated in the room?

If you don't want to measure with a microphone you could get a test CD and just listen. There are two I'd suggest:

https://realtraps.com/test-cd.htm

This will tell you how your bass is doing.

https://www.discogs.com/release/9922972-Various-Gold-Stereo-And-Surround-Sound-Set-Up-Disc

I don't know if this is available anymore but it has channel balance tests amongst others.

There may be more modern ones that I'm not aware of.

Thank you for the reply Hipper.

I appreciate your reply. Though I am aware of all of the info you posted. As I mentioned earlier I've had subwoofers in the system, using DSP and got rid of them a while back - didn't improve the sound enough and hated the added hassle, cabling, more speakers in the room etc. I wasn't actually looking for advice for changing things as I have already worked within the limitations of the room and I'm extremely happy with the sound. (I think the job was done about as well as possible...we sweated the details heavily in designing the room, forms of trapping/bass trapping etc hidden in to room corners, ceiling areas etc - a couple installers also said it was among the most coherent sounding set ups for surround sound they'd ever heard).

As I said, it was so long ago I'd forgotten the specifics of what the acoustician explained at the time. I was mostly using my own room for a general question, curious about the pros and cons of room openings like that, especially with a speaker near the opening, in terms of bass frequency.

 

[caught gesture]

It really is a simple matter to measure your room with REW. I think that should be the starting point before any discussion on how a room sounds. It allows us, the participants in a discussion, an insight that is unavailable from just looking at photos/plans and a written description of the perceived sound. It is also really helpful to you if you are genuinely interested in how your room interacts with your equipment. If you think it sounds great and have no intention of changing anything, I’d question your need to start the thread.

 

[Willem]

Earl Geddes argues that for deep bass a room's volume is more important than its shape, and that large openings simply add to that volume, lowering the Schroeder frequency and hence the frequencies of room modes, making them less obnoxious and easier to equalize. We use our large living room with large openings with sliding doors to the dining room and my wife's study as a music room and I have been quite happy. With the double doors to the hall closed, the room is about 7000 cubic feet, but with those doors to the hall wide open it would be quite a bit larger still. I am currently planning to add one or more subwoofers to the existing one, and will measure when that is done.

 

[MattHooper]

It really is a simple matter to measure your room with REW. I think that should be the starting point before any discussion on how a room sounds. It allows us, the participants in a discussion, an insight that is unavailable from just looking at photos/plans and a written description of the perceived sound. It is also really helpful to you if you are genuinely interested in how your room interacts with your equipment. If you think it sounds great and have no intention of changing anything, I’d question your need to start the thread.

Understandable. And thanks for your advice.

However I don't have the measuring equipment (also got rid of my subwoofer/dsp stuff a while back) and since I'm happy with the sound, don't feel the need. The reason for the thread was, as stated, I wondered if there was some obvious basic principles that apply to the effect of room openings such as this - how it affects the notion of "how big your room is" in terms of bass frequencies etc. I'm not actually sure what measuring my room would do for the question anyway, since I wouldn't be doing a "with room opening/without room opening" comparison - which is why I was looking for general principles.

I've had some answers along the lines I was looking for.

 

[caught gesture]

Understandable. And thanks for your advice.

However I don't have the measuring equipment (also got rid of my subwoofer/dsp stuff a while back) and since I'm happy with the sound, don't feel the need. The reason for the thread was, as stated, I wondered if there was some obvious basic principles that apply to the effect of room openings such as this - how it affects the notion of "how big your room is" in terms of bass frequencies etc. I'm not actually sure what measuring my room would do for the question anyway, since I wouldn't be doing a "with room opening/without room opening" comparison - which is why I was looking for general principles.

I've had some answers along the lines I was looking for.

I’ve got a room with multiple openings and yet the room modes are pretty consistent to the basic dimensions of the room. @dasdoing on a thread I started directed me to a great site for figuring out the modes based on dimensions of room.

 

[MattHooper]

Excellent. Thank you caught gesture !!

 

[Axo1989]

I’ve got a room with multiple openings and yet the room modes are pretty consistent to the basic dimensions of the room. @dasdoing on a thread I started directed me to a great site for figuring out the modes based on dimensions of room.

That AMROC toool is great. I've used it as a diagnostic (along with REW's room model) and for general curiosity.

A limitation of both is the simple rectangular geometry. You can however simply enter relevant dimensions for complex/extended spaces like Matt's adjacent corridor/open hall. The lateral modes at the opening will correspond to the larger width (or length) of the combined space. As discussed, this won't dominate at the listening position. And the interactions are complex: below Schroeder, bass acts like pressure waves, whereas frequencies above act like vectors (so the Amcoustics ray-tracing tool is also fun to try). I often imagine rooms as a large speaker enclosure, with internal drivers.

There are softwares for dynamic 3D modelling, but expensive with a learning curve, so out of scope here. I'd love an acoustic plug-in for a user-friendly 3D drawing tool like SketchUp, where you could assign relevant characteristics to internal surfaces/materials, etc, but that's unlikely.