Is a very big listening room as bad as a very small one?

[treitz3]

If one were to think that rooms do not change the acoustics (room acoustics), then the same logic would be true for changing the size of your speakers, no?

I think I speak for everyone when I say that there is a major flaw with that kind of thinking/thought process, as we all know that changing the size of your speaker (keeping everything else the same) has a major influence on the end result as to what hits your ears.

Now with that said, I have heard my system in very large, open rooms 2 stories tall and in a small 13x15 room. The acoustics of the room plays a big difference in what you hear. Not just for sound pressure either.

So, basically, my experience does not mimic that thought process.

Tom

 

[KlausR.]

In regards to "minimizing standing waves" (which is an inaccurate description) I'm referring to the Schroeder frequency changing with a bigger room. It's certainly a lot easier to achieve a better low frequency result in larger rooms compared to very small ones.

Schroeder examined the following statistical quantities of the frequency response curve of "large rooms": the rms response fluctuation, the average height of a maximum, the mean spacing of the zeros (i.e., the intersections of the response curve with the mean level), the mean spacing of the maxima, the mean rate of phase rotation per hertz, and finally the so-called frequency irregularity.

He noted the following: "It is assumed above that the number of simultaneously excited, independent modes is large enough to yield a Gaussian distribution of the sound pressure components. Practical experience has shown that the approximation of the Gaussian distribution is good for about 10 independent components of the same order of magnitude." He then presented his formula for what is called the Schroeder-frequency.

In practice this means that above a certain frequency the mode frequencies are spaced closely enough that excitation of one mode will excite also the neighbouring modes, the amplitude response becomes flatter/smoother. It has been found that the transition occurs at a frequency which Schroeder initially determined, i.e. f= 4000 ?T/V (T = RT60, V=room volume).

In a larger room you have more eigenfrequencies in the same frequency range, whether this leads to a smoother response depends on position of source and listener.

Always learn in this hobby

klaus says there’s no such thing as room acoustics.I think there is.

What I mean is that if you change position of speakers and listener you don't change the room, but you get a different response. So it's not the room but the interaction of room and speakers. It then depends where the listener is located with respect to the speakers, another interaction not depending on the (unchanged) room. A room does not have its own unique acoustics, apart from RT60 that is, since what you hear does not depend on the room, which remains strictly the same, but on the two interactions.

Klaus

 

[KlausR.]

If one were to think that rooms do not change the acoustics (room acoustics), then the same logic would be true for changing the size of your speakers, no?

I think I speak for everyone when I say that there is a major flaw with that kind of thinking/thought process, as we all know that changing the size of your speaker (keeping everything else the same) has a major influence on the end result as to what hits your ears.

Now with that said, I have heard my system in very large, open rooms 2 stories tall and in a small 13x15 room. The acoustics of the room plays a big difference in what you hear. Not just for sound pressure either.

So, basically, my experience does not mimic that thought process.

Tom

Well, I think that if you put the same drivers and Xover in a larger cabinet while keeping everything else constant (bass cabinet volume, location of drivers w.r.t each other) and place it such that the drivers are in the same location w.r.t. the room boundaries, then nothing changes. If you are concerned about cabinet edge reflections, then build a new cabinet of the same height and width, but twice the depth with an inner partition wall so that the front section is identical to the smaller cabinet.

Of course, when you put the same speakers in two different rooms, the result will (lost likely) be different, simply because on top of different RT60 you have different speaker/room interactions. When you change position of speakers and listening chair in your own room you (most likely) will get a different result, for the very same reason. The only thing the room in itself adds to the equation is reverberation, everything else is speaker/room interaction.

Klaus

 

[amhifi]

Thats quite a room and gear you got there shaki.....

You get a -6db loss of spl with the doubling of distance .. so at 8m you lose 18db of spl compared to 1m ( 6db at 2m , 12 db at 4 and 18db at 8m) .. you also get a greater drop in treble with increased distance on top of just the SPL loss ...

If for eg , your speakers are 90db efficient at 1 w , you need around 64 W to get to the same 90 db SPL at 8m..listening at a max of 100db (pretty loud) with those speakers you would need around 2000w of amp power at 8m....

I wouldnt be listening to speakers at anything more than 8m distance anyway .. I listen at about 5m

Some pics of my room in this thread , with my old G1s not my current Giya G1 Spirits

http://www.whatsbestforum.com/showt...n-Wood-Floor-and-Walls-of-Brown-Wood-Paneling

"You get a -6db loss of spl with the doubling of distance"
That is in free space from a point source - which means no reflecting surfaces in any direction. Even ground plane measurements outside have one reflecting surface. Have you ever measured your room? In my theater room, which has a significant amount of absorbing room treatment, the difference on pink noise at 1m and 2m is between 3.7 and 4 dB A-weighted. I used A-weighting to reduce the effects of low frequency room nodes. I expect in rooms with less absorbing material the difference would be closer to 3 dB.

 

[ddk]

"You get a -6db loss of spl with the doubling of distance"
That is in free space from a point source - which means no reflecting surfaces in any direction. Even ground plane measurements outside have one reflecting surface. Have you ever measured your room? In my theater room, which has a significant amount of absorbing room treatment, the difference on pink noise at 1m and 2m is between 3.7 and 4 dB A-weighted. I used A-weighting to reduce the effects of low frequency room nodes. I expect in rooms with less absorbing material the difference would be closer to 3 dB.

This is an old thread and unfortunately Rodney has passed since.

david

 

[KlausR.]

I expect in rooms with less absorbing material the difference would be closer to 3 dB.

It's approximately 3 dB.

T. J. Schultz, “Improved Relationship between Sound Power Level and Sound Pressure Level in Domestic
and Office Spaces,” Rep. 5290, American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE)

Klaus

 

[Dennis Foley]

Dear & fellow forum members,

I researched about ideal room dimensions and acoustic treatments about building a new listening room in the forum and I have plenty of information about these two subjects.

One thing I couldn't find out is the IDEAL ROOM SIZE for a full range speaker system in terms of SIZE not ratios of sides. All I could find is the ideal ratio of length x width x height of the room.

But what is the size of the perfect listening room keeping the ratios constant? I know an ideal size of the room also depends on the speaker but let's keep that constant too. A full range speaker like Wilson Alexx, Alexia or Magico S7.

I can build a room as big as 33W x 46L x 16H (feet) within the ideal ratio but is it too big for a standard full range speaker experience?

Should I restrict the room size and make it smaller to achieve more sound pressure in the room?

Is a very big room as bad as a very small room?

I don't want to end up having the perfect listening room in terms of ratios and acoustic treatment but ending up Alexias playing like a bookshelf.

I am exaggerating of course but I believe there is truth to what I am saying.

I will be grateful if you can share your wisdom about this subject with me.

Love and respect,

Cagdas

Each room size/volume/usage will have its own set of issues. If the room is small with full range usage, you will have numerous unwanted pressure issues below 100 Hz. If the room is larger, you will have to deal with reflections from boundary surfaces that increase Rt-30/60 times. There is no one size fits all or a free ride.

 

[Dennis Foley]

If one were to think that rooms do not change the acoustics (room acoustics), then the same logic would be true for changing the size of your speakers, no?

I think I speak for everyone when I say that there is a major flaw with that kind of thinking/thought process, as we all know that changing the size of your speaker (keeping everything else the same) has a major influence on the end result as to what hits your ears.

Now with that said, I have heard my system in very large, open rooms 2 stories tall and in a small 13x15 room. The acoustics of the room plays a big difference in what you hear. Not just for sound pressure either.

So, basically, my experience does not mimic that thought process.

Tom

The size/volume/usage of your room will either exaggerate or minimize the issues the room produces. Rooms only see energy. The source of the energy is not relevant. Large amounts of energy will excite large amounts of issues. All small rooms produce unwanted low-frequency energy issues. Begin your treatment focus on those lower frequencies below 100 Hz. Once those issues have been managed, move into the middle and high frequency treatment issues. Diffusion and absorption are your tools to use for ray energy treatment. Make sure you choose treatment types that have the proper rates and levels of absorption for music and voice. Music and voice are different than noise.

 

[Forecast]

The possible size of the room depends you your speaker system and your listening distance. Depending on your speaker, you will loose nearly 3db SPL per meter distance, so 10m distance can end up in 30db lost of SPL. If your speaker makes a max of 105db SPL (which is normal for many), you will have on your listening position only 75db max SPL. My home cinema has 12m and we stay at the bar, the speakers are like 10m away, many standard speakers have a real problem to make this distance .

Some Speakers are designed for large distances, for instance man Horn Speakers.

If we are talking the width of the room, I would say, cannot be enough , as you avoid side reflections.

My personal listening room is around 60sqm and is 3,1m high. There are nearly no parallel walls, but unfortunately a lot of windows, so planar speakers so not work properly.

I like rooms between 50 and 100 sqm, as you can sit close enough, without damaging the room harmony and the room is big enough for some bass.

If the rooms are bigger than 100 sqm, mostly the listening distance is getting too big and you need to look for speakers which can make that in tonal balance and time.

I added a picture of my room (still with Zingali, the hORNS will arrive tomorrow) , you can see that 60sqm will get "small" very fast, if you have some big footprint gear, like the CAT JL3 .



View attachment 41262

At first glance it seemed that what a horror, a large room, a lot of windows and only two diffusers. but after looking closer I saw and absorbing panels and bass traps and all this I would call it diffuse furniture and this huge sofa which I think also absorbs enough. it all looks very cool.