How do you chose speakers based on room size?

I haven't seen a guide that discusses how to size speakers based on the room that they will be placed. What is the proper method to mate the two?
Different speaker types (dynamic/cones, panels/line sources, and electrostatics, all have different set up/room size requirements. Generally in a smallish room, for optimal set up, panels, line sources, and electrostatics will not work as well as dynamic ones and these should be of the stand mount type which reduces the distance required from speaker to ear needed to get proper integration of the multiple drivers.

You really need to feed specifics re room size, listening preferences, and set up restrictions, to get any kind of a meaningful answer. There is no meaningful 'guide' but you can get some good practical advise if you provide some more info.
An oversimplification would be:
Small room - small speaker
medium sized room - medium sized speakers
large room - large speakers



Small rooms are the most difficult. You have at least three acoustic issues in a small room:

1. Early onset of reflections (causes coloration and/or compromised imaging);

2. Worse room modal situation than in larger rooms so the bass is lumpier;

3. Often excessive room gain in the bass region (depends on many factors including speaker and listener locations).

In a very large room, the speaker's power response (summed omnidirectional response) tends to dominate the perceived tonal balance, so that matters a lot more than the on-axis response does (unless you listen nearfield), and often in a large or open-floorplan room the boundary reinforcement is insufficient in the bass region so the speaker tends to sound thin and weak. Also the higher power levels required to reach satisfying SPLs in a larger room can tax a speaker both thermally and mechanically.

I recently did a fair amount of experimenting in the course of investigating a small-room-friendly speaker system, and came to some rather ironic conclusions. For example, in order to get the radiation pattern control that gives good performance in a small room by minimizing early reflections, a physically rather large speaker is required.

Now there is a school of thought that calls for very aggressive use of absorption on the walls of a small room, and this relaxes the radiation pattern control requirement. Unfortunately this approach also eliminates beneficial late-arriving reverberant energy.

I recommend spreading out the bass sources as much as is practical regardless of room size as this smooths the in-room bass response (I can explain why if you'd like). Even a little bit of spacing can be beneficial; for instance, a two-way floorstander with the port on the rear down near the floor has the two bass sources (woofer and port) fairly far apart in two dimensions, and this will usually sound smoother than having the woofer and port displaced in only one dimension. If excess boundary reinforcement is an issue, that can often be addressed by reducing the port tuning frequency (which is easier to do than raising the tuning frequency).

For best imaging and soundstage, you want a tight driver configuration that approximates a point source in smaller room with more a more nearfield listening configuration.

Planars, line sources, etc. with larger sound emitting area can work well in larger rooms listening from farther away.

Also, larger bass drivers in general or possibly a separate sub woofer will be needed to get a fulfilling low end in larger rooms.

Also, many speakers image best with more room to breath around them (distance to walls) so never try to cram too large a speaker into any particular space.

That's the jist of it regarding guidelines I can think of.

Some vendors, like OHM Acoustics, explicitly scale their drivers up and down in size for similar optimal sound in specific room volumes that they specify on their web site..
As has already been stated, small rooms are problematic. The smaller the room, the more important that acoustic treatments become.

A few rules:

The listening position always needs to be at least 18" from the wall behind. Less than that, and the low frequencies there will smear the sound.

The distance from the speaker front to the listening position needs to be around 9' to give the sound time to integrate. Less space is OK for single driver speakers since the sound is integrated to moment it leaves the driver. This distance really depends upon the distance between the drivers, but 9' is probably safe for most speakers.

Some speakers need to be out from the wall behind. This is especially true of dipoles - planars and electrostatics. These need about 4' from the wall behind. This is so the sound coming off the back will integrate with that coming off the front.

Other speakers seem to be at their best shoved up against the wall. This seems to be the especially case with BLH designs.

Given these parameters, we can see how a small room may become a problem depending upon the speaker. If the speaker needs 4' from the wall behind, and we need 9' for integration and the listening position needs to be 1.5' from the rear wall, we have a total of 14.5'. Obviously, if we do not have that, we may have a problem.

We really cannot do anything about the 18" off the wall behind the listening position. That is a given. The options then become a). selecting speakers that can be placed close the the wall, b) using single driver speakers that require less space for integration or c). a combination of the a) and b).

I am using Klipsch Chorus II in a room that is 10.5 by 12.5'. These are 3 way speakers with a 15" bass driver. This works because these can be placed close to the wall behind. I have space for the 9' of integration and for the listening position to be 18' off the wall. My room has extensive acoustic treatments. Actually, my experience has been that once I had the room under control, whatever I put in there sounded pretty darned good. Before the treatments, it was an echo chamber.

Hope this helps.
It costs a lot less to get a great sounding system in a smaller room. Its not that complicated. Smaller speakers + lower power amp typically brings the cost down a lot (except for Magico). And fewer room treatments if you decide those are necesary.
Hi Duke,

Have you ever tried DSP as a "room" or perhaps, more appropriately - system treatment?

J Bailey, your experience with the large-format Klipsch Chorus II's in a relatively small room makes sense to me. They probably benefit from generous boundary reinforcement, and are directional enough to avoid the onslaught of early reflections that one typically is met with.

C1ferrari/Sam, regarding DSP, once in a large room (ballpark 80 feet by 120 feet) we used DSP as a "room/system treatment", and it was definitely an improvement. My speakers didn't have adequate bass output in that size room especially with the positioning we had to use, although they did have enough excursion capability to handle the EQ. A rather sophisticated prosound DSP package was used, and we spent about an hour taking measurements in a wide variety of microphone positions.

Also when Robert E. Greene (of TAS) had a pair of my bipolars in his room some time ago, he experimented with at least one DSP room-correction system (something he is quite fond of). He reported in his online forum that the DSP correction made very little change to what the speakers were doing, which he said was indicative of good in-room behavior.

Two things that DSP cannot do anything about are the loudspeaker's radiation pattern and physical limits (both thermal and mechanical). So to get the most benefit from a DSP-corrected system, in my opinion it's a good idea to start out with speakers that do a good job in those two areas.
Thanks, Duke for the erudite reply...I have a lot to learn/experience and appreciate the selflessness exhibited by you and others in our community.

Best for the New Year,
Timely topic. I've got an open plan listening area--my my living room--that is roughly 15' long and 11'3" wide with a "mostly" open wall on the longer side (that is, from the back/listening end wall, the open wallspace extends about 11-12' toward the speaker end). 7'6" ceiling. I am using B&W CDM7se floorstanders.

If there is a problem presently it is with a weaker lower end. (Duke hit the nail perfectly.) Overall positioning has been tweaked to the point where I am happy with the sound but I cannot seem to get past the bass issue. On most recordings I really don't notice (but imagine that there is still an effect that will be appreciated if the issue is corrected) while on others the lack is clearly noticeable.

We've got carpet on the floor and upholstered loveseats at both the closed side and at the listening location. I'm guessing these don't help the bass but the rest of the frequency range sound so good I'm in a quandry.

The wife and I would like to put in hardwood and to replace the loveseats (the cats are slowly shredding them) with leather but I am really nervous about "hollowing out" what is now an otherwise very rich sound (absent some degree of bass).

My speakers of choice (the next upgrade) would be the larger B&W 803D which also have the benefit of better (and additional) drivers and B&W's diamond tweeter. ( I'd been concerned that the size was a problem but Duke has suggested otherwise. Any comments on current setup or proposed changes (gear or room) would be greatly appreciated.
I always said that the more the room acoustics become a challenge. You have to try a listening triangle in that room as a starting point and choose your speaker type.
This is a great thread !

I was wondering if we could take this a step further ?

Is there some aspect of speaker build/design that one should look for in those small room/nearfield situations that would be different than the larger rooms and visa- versa ? Something that would not be placement specific .

In the larger room one will want to turn up the volume so as to pressurize the room while sitting farther away from the speakers . But in a small room one will want to turn down the volume because there is less area to pressurize and you are sitting closer the speakers .

Newbee addressed speaker types , Duke talks about spreading the bass sources and reducing the port frequency in a tight space , mapman suggests tight driver integration for small rooms and bigger drivers for large rooms . But then J Bailey speaks of single drivers for easier driver integration and uses 3 way big woofer back loaded horn speakers in his small room .

Are there some simple guidlines for design as well as size ?

Thank you .
Saki, Speaker placement (including the rooms that they might work well in) is critical for just about every speaker design.

Some folks pursue set up diligently until they have optimized it, some more than others until their significant other or their own sense of asthetics takes over, some not at all and everything in between.

Your suggestion raises the toughest and most common (I think) situation facing the majority of audiophiles. Good sound in a small room. Tough under the best of circumstances and especially so if your expectations are demanding, but to exclude placement as a consideration presumes that there is a speaker with audiophile pretensions which will sound good no matter where you put it or where you sit when you listen to it.

I don't know of such a speaker, let alone provide 'simple guidelines' or advise, apart from getting a pair of sealed enclosure cone driver monitors that can be placed near a wall or on a book shelf, a sub woofer to fill out the bottom end, and an equalizer of some sort to balance out the very uneven sound that would be likely. Not very good advise IMHO unless you don't care about things like a balanced FR at the listening position as well as a full (wide/high/deep) sound-stage.


Saki70, you have very good questions. I'm going to avoid getting too specific here because I don't want my post to cross the line and become an "ad".

Driver integration is dependent on driver vertical spacing, crossover frequency & slope, and listening distance. Briefly, the ear is poor at resolving the height of a sound source below about 1 kHz, improves dramatically between 1 kHz and 4 kHz (where it peaks), and then actually decreases a bit at higher frequencies but remains pretty good. Steep-slope crossovers give better driver integration (less vertical smearing) at close range than shallow-slope crossovers. In my experience, having a suitably low crossover frequency is more beneficial to driver integration than is close inter-driver spacing. Perhaps Clio09 will post here, as he's the one who really opened my eyes (and ears) on this subject.

Saki70, you mentioned that in a larger room we want to crank it a bit but in a smaller room we want to turn the volume down. One factor that comes into play here is the thermal modulation characteristics of the drivers. Usually the tweeter is more efficient than the woofer so it's padded down, and it normally gets a lot less power anyway. So many speakers run into the problem of the woofer's voice coil heating up more than the tweeter's voice coil, so the woofer has more thermal compression as we turn the volume knob higher. This voice coil heating is virtually instantaneous; a 100-watt transient is like touching a 100-watt soldering iron to the voice coil. Anyway, if the woofer's voice coil is heating up faster than the tweeter's it will have more thermal compression at high input levels. The designer then has to choose an input level at which the drivers are balanced relative to one another, and he will probably choose a fairly high level, let's say 90 dB/1 meter for this example. If we go to 100 dB, the tweeter will get loud a bit faster than the woofer because its thermal compression is less, so the speaker will sound a bit bright on peaks. If we go down to 60 or 70 dB, now the tweeter is softer than the woofer so the speaker sounds a bit dull and lifeless. I think this phenomenon is behind the fact that many speakers do not really "come to life" until you crank 'em up a bit.

So to sum up the preceding paragraph, it's not uncommon for a speaker's tonal balance to change with the input power level, going from dull at low levels to "just right" (the Goldilocks zone) to too bright at very high levels. If a speaker is going to work well at a wide range of power levels, either the woofer and tweeter need to have very similar thermal compression characteristics or their departure from linearity should happen at higher input power levels than we're likely to see in the home.

On a related note, low thermal compression correlates with speakers that convey emotion well. Musicians use variations in loudness to convey emotion, and it's nice if the speakers can preserve those dynamic shadings. If a speaker is compressing the peaks by 2 or 3 dB, well then ou lose emotional impact.

So anyway in order to meet the requirement that a speaker work well at low levels in a small room and also at high levels in a large room, a lot of issues have to be addressed. I think it's easier to address them with prosound drivers, but won't claim that's the only feasible approach. But large-diameter prosound woofers and high quality constant-directivity horns & waveguides combine good directional control with the ability to move a lot of air should they be called upon to do so.

I don't think it's possible to design a speaker whose characteristics in the bass region do not change significantly as its position in the room (and/or the room itself) is changed, so I think the best we can do is build in a reasonable amount of adaptability that will hopefully cover most situations.

Wow Duke.

Thanks for that explanation about varying thermal compression of drivers.

It suddenly makes a whole lot of experiences I have had listening to speakers, understandable.

What about an L shaped 12Wx19Lx8 ft ceilings with an ajoining dining room WP 7s 8s or could you sqeeze Maxx 2s in there? I do have 1 pair 16"x 48" tube traps to use.
Thanks, Halcro. There can be other reasons for the perceived tonal balance to change with level, but I think differing thermal compression characteristics among drivers is usually the main one.

Heykay, even though your 12 by 19 foot room would probably be considered "medium sized", the fact that it's open into another large room means that it's in effect a "large" room as far as the bass region goes. My opinion would be, either go with speakers "voiced" for a large room or consider using a sub with the intention of adding a little bit more energy across the bass region (rather than merely filling in below the main speakers, which is the more common usage for a sub). In many cases an opening into an adjoining room acts as a huge bass trap and can actually be beneficial, provided you can get the bass level up enough to offset the loss of bass energy.

Duke, That explains alot and makes a good case for a midrange driver that covers as much frequency range as possible.
I forgot to mention that I do have a Rel Studio III and I was using it with Sophia 1s which I just sold and was going to upgrade to the 7s or 8s but was curius about room size and Maxx 2s the height looks like it might be an issue with eight foot ceilings in room. And also on my rear right behind seating there is a long hallway that opens to bedrooms.
Duke ;

Like the others ...your explanation has cleared up a lot of things that I have noticed along the way ! Thank you .

What I was trying to get at concerning the 'guidelines' were things to look for that were specific to the size of room that the speakers are to be used in , not an all in one approach .
What design characteristics would be favorable for speakers in a small room that would not be favorable for speakers that were to be used in a large room and visa/versa ?

Thank you .
"What design characteristics would be favorable for speakers in a small room that would not be favorable for speakers that were to be used in a large room and visa/versa?"

Well this depends somewhat on where the speakers are located within the room but in my opinion in a small room you generally want the bass rolloff to start fairly high but it can be gentle. This should synergize better with the anticipated boundary reinforcement than a speaker that is "flat" down to a fairly low frequency. Conversely, in a big room you need speakers with more bass output, relatively speaking, because the room isn't going to help you out as much.

In any size room I like fairly uniform radiation patterns in the midrange and treble region. In a small room I like a fairly narrow pattern that can be aimed to minimize early sidewall reflections, but there are people who like omnis in small rooms (the reflections from an omni are likely to be spectrally correct, which is desirable). I like to have at least a 7 millisecond delay before the onset of reflections other than the floor or ceiling bounce, and that corresponds to a path length difference of about 7 feet. So something like baby Maggies located 3.5 feet in front of the wall would probably be feasible (I'd prefer 5 feet out, but we're talking about the minimums here).

In a medium or large room where we'll have a good 10 milliseconds or more before the onset of reflections from nearby walls, we can freely use speakers that have a wider pattern (dipoles, bipoles and omnis conceptually fit into this category if they can be placed far enough out into the room)). Such speakers give a greater relative level of reverberant energy in the room and in my opinon more closely approximates the sort of soundfield we experience at a live performance. Now there are competing schools of thought that object to "adding" reverberant energy via wide-pattern speakers, but that's another topic for another day.

So to recap, you usually need a lot of bass output in a big room but not nearly as much in a small room, and (in Duke's opinion anyway) wide-pattern speakers are better suited for medium or large rooms than for small rooms.
"Duke, That explains alot and makes a good case for a midrange driver that covers as much frequency range as possible. "

Consistent also with my positive experience using OHM Walsh and Triangle 2-way monitor speakers in my small room, both of which cover a wide range through a single driver I believe. Similar expererience using my 2-way Dynaudio Contour line monitors as well.

Ideally, for coherent imaging and sound, you do not want different mid and high frequency ranges to be coming from different locations. Wide range drivers and drivers located closer together physically is what is needed to a greater extent to produce this ideal geometry when listening more nearfield in a smaller room, where the ears are capable of triangulating better on the exact source of sound.

From farther away in a large room, it is less of an issue.

Basically, in smaller rooms, the best things also happen to come quite often in smaller packages.
"In a small room I like a fairly narrow pattern that can be aimed to minimize early sidewall reflections"

Duke , is this why some speakers have the driver recessed from the front face of the speaker box and others put some type of built up ring around the driver if it is mounted on the face ? Or a narrow dispersion horn usage rather than a wide dispersion horn ? Would these perhaps be design features to look for if considering a small room speaker ?

And finally , what is your take on back loaded horns as suggested by J Bailey ? And speakers like the Altec 15 and 19 , used in small rooms in the Orient , where they are slammed up against the wall behind them but also used successfully away from the back wall in a larger room such as member 'T bone' does ?

Thank you .
""In a small room I like a fairly narrow pattern that can be aimed to minimize early sidewall reflections""

For me there are two viable approaches to fitting speakers into a particular room, large or small:

1) Do everything you can to isolate the speakers from room acoustics in order to hear just the recording and not the room

2) accept the room as your particular concert venue and utilize it

In the first case, more directional speakers or external tweaks that accomplish the same thing (see the isolated location of my Triangle monitors in my second system listing) are the solution, particularly in tight or limited quarters.

In the second case, omnis or other wide dispersion designs are the ticket.

Each sounds inherently different but both are viable approaches depending on the listener's goals.

I like and utilize both approaches in different rooms in my house, but, push come to shove, I tend to prefer the wide-dispersion approach.
Saki70, I'd have to see the speaker (and preferably know its crossover frequency) to make a judgment about its radiation pattern.

The room gain you get in a small room plays right into the hands of a good back-loaded horn that exits into a corner. That's an excellent, very high bang-for-the-buck format in my opinion. For instance I don't see how I could compete with what Ed Schilling is doing in that area.

And yup, your example of big Altecs in small Asian rooms is consistent with what I'm talking about.

Mapman, I'm encouraged by how many people find success with the Ohms in a small room. The Ohms aren't just wide-pattern speakers; they are wide, uniform pattern speakers - so their reverberant field is spectrally balanced. I suspect that there is a correlation between how good they sound in a small room and how far away from the walls they are positioned. Having experimented with fairly uniform-pattern quasi-omnis, that was my conclusion: Get 'em out from the walls and they can work great in a small room. My finding was that if they can't be pulled out at least 3.5 feet into the room, then controlled-pattern monopoles work better.

Have you found a correlation between sound quality and distance from the walls with your Ohms?
Interesting thread, and timing, to me as well as we are looking at buildng a new house and in the new house my wife would like my system to not be in the living room, but rather in its own room that will also be my office. The challenge has been finding floor plans we can use (and afford) that I feel will have a room large enough, yet I really don't know what "large enough" is. Budget will play a large role in what size room can be afforded.

Another issue is windows, they are a must for asthetics but suspect not the best for sound; I also will have hardwood floors, though a throw rug will be put down.

One of my concerns is sound off the back wall and I was surprised to read the comments above where they thought 18" was sufficient. My current room has my system in the living room. The speakers, facing me, face into the kitchen/dining room, so this is the full width of the house, 30'; I clearly hear more bass if I go to that back wall. Any (stereo) room in the new house would have me much closer to the back wall.

The smaller OHMs can work surprisingly well just a foot or two out from the rear and side wall in that acoustic dampening material is used inside the can in the wall facing directions to lower output and enable closer placement to walls than would be desirable otherwise. Still I do tend to keep my 100s about 2-3 feet out from the rear wall or so.