Due to a lack of vertical space I want to place my studio monitors horizontally. So I need to know if the tweeters should be on the inside or the outside when the speakers are placed on their sides.
This turned out to be more complicated than I expected. I thought I would share what I found out.
Tweeters and Woofers
Monitor speakers in a music studio are normally placed either side of the mixing desk, or maybe just either side of your computer in a home studio.
As you probably know, most studio monitor speakers have two drivers. A driver is the circular unit that produces the sound, so I’ll refer to the individual speakers in a studio monitor unit as drivers to avoid confusion.
Also, we’re talking about near-field monitors here, which are designed to be placed fairly close to the listener. You can read more about studio monitor speakers in this article.
A typical two-way unit has a larger low-frequency driver called a “woofer” (or sometimes called a “mid”), and a smaller high-frequency driver called a “tweeter”. These drivers are normally mounted in a cabinet with the tweeter above the woofer.
There probably isn’t much disagreement about whether the tweeter should be placed above the woofer.
However, if you want to position the speaker cabinets horizontally there seem to be different opinions on whether the tweeters should be on the inside or the outside of the pair.
There are arguments for and against placing tweeters on the inside or outside when studio monitor speakers are placed horizontally. The most convincing seem to support placing tweeters on the inside to produce the most accurate stereo image.
Should Studio Monitors Be Placed Horizontally at All?
As soon as I started researching the question of whether the tweeters should be on the inside or outside I started to find information on horizontal vs vertical placement.
It seems that many studio monitors are designed to be placed vertically and problems can result if you place them horizontally.
If it turned out that placing the monitors horizontally was a bad idea then I would probably have to avoid doing that and the question of tweeters inside or out would be irrelevant.
Tweeters and Woofers Located a Different Distance From Your Ears
The main problem when placing monitors horizontally is that the tweeter and woofer drivers are not the same distance from your ears.
The speaker unit normally contains a “crossover” component. This takes the audio signal coming in and splits it, with the lower frequencies going to the mid/woofer driver, and the higher frequencies going to the tweeter driver.
You can read more about this in Studio Monitor Speakers – 5 Things You Should Know About.
When monitors are placed vertically one driver is directly above the other and so they the distance between each driver and your ears is the same. This means that a proper stereo image can be produced.
When the monitors are placed horizontally one driver is further away from your ears than the other. If the tweeters are on the outside they are further way than the woofers, and if they are on they outside they are closer.
Out of Phase Sound Waves Can Produce Comb Filtering
This means the sound from the two drivers arrives in your ears at different times. I found some very complicated explanations of why this can be a problem, much of which was about phase issues to the audio signals from each driver being out of alignment.
The main problems are caused by “comb filtering”. This is where the out-of-phase sound waves produced constructive and destructive interference.
This results in cancelling out of some parts of the sound and reinforcement of others, giving the sound waves the appearance of a comb when viewed in an oscilloscope.
Placing the Monitor Speakers in a Triangle With Your Head
A lot of this didn’t make much sense in relation to the advice regarding studio monitor placement in a small studio space.
This advice suggests you have them pointing inwards so that they form two corners of an equilateral triangle, with your head forming the third corner.
Placing the monitors in this way, with the front faces pointing directly at your head, should eliminate this problem since each driver is now about the same distance from your ears.
However, if you have the monitors placed flush against a wall or the back of your desk the tweeters and woofers could still be at a different distance, so the potential problem would still be present.
Speakers Closer to Surfaces Than Intended
Other potential problems resulting from horizontal placement of monitors intended for vertical use depend on the design of the unit. For example, the drivers could end up being closer to the surface they are placed on than intended.
Being closer to surfaces can result in absorption and reflection of sound waves not intended by the designers of the speakers.
This could produce changes in the way different frequencies are delivered to your ears, leading to a less faithful representation of the sound.
One way of addressing this would be to place the monitors on stands rather than directly onto a surface.
Tweeters Inside or Outside?
There are various things that have to be considered before placing studio monitors horizontally. However, with some care regarding placement (as outlined above) problems can be avoided.
Having been satisfied that it should okay to place the monitors horizontally, the next question is whether the tweeters should be on the inside or the outside.
There seem to be different views on this, and the information is often presented as facts, which makes things even more confusing.
Arguments for Tweeters on the Outside
It’s easier for our sense of hearing to place higher-pitched sounds than lower-pitched sounds. Low-pitched sounds are less directional.
This is why people often have speaker for very low frequencies – a sub-woofer – rather than two. You can’t really tell where very low frequency sound is coming from so one speaker will often do the job.
This should mean that placing the tweeters on the outside would produce the best stereo separation, and result in the most faithful stereo image.
This is because your ears place the higher-pitched sounds much more precisely than the lower-pitched sound coming from the mid/woofer speakers located on the inside.
That’s the theory anyway.
It seems that this idea of placing the tweeters on the outside to widen the stereo image is left over from the way stereo recordings used to be produced.
This used to help with the very wide separation of voices and instruments that were employed in years gone by. In some cases instruments would be panned hard left or hard right. If you listen to old Beatles records you can really hear this.
This doesn’t work so well now that recording engineers are able to produce a much more sophisticated stereo image. This is achieved with effects like panning, compression and reverb.
Arguments for Tweeters on the Inside
Having looked at some of the pros and cons of outside tweeter placement, what about placing the tweeters on the inside?
The arguments for placing horizontal monitor speakers with the tweeters on the inside seem to focus on the accuracy of the stereo image produced. This is in contrast to the width of the stereo image with tweeters on the outside.
Since you are sitting in between the two speakers the theory is that the very directional higher-pitched sounds will be inside the less directional lower-pitched sounds coming from the mid/woofer drivers.
Should You Just Listen and See What You Prefer?
A lot of the advice I found suggested that you try a blindfold test to see which arrangement you prefer.
With a domestic stereo set-up that might be good advice. However, I think the aim with studio monitor speakers is to produce as faithful a representation of the audio signal as possible.
This is why I’m finding this so tricky. If one set-up – either tweeters inside or outside – sounds better than the other, then that could be dangerous. It’s the accuracy of the representation that is the most important thing in a recording studio.
I’m more convinced by the tweeters on the inside arguments, so I’m going to go with that. The accuracy of the stereo image and the balanced sound is more compelling, so that’s the way I’m going to go with this.