Can You Stack Bookshelf Speakers?

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Can You Stack Bookshelf Speakers?


Can you stack bookshelf speakers? It’s a good question really, and might even be one you’ve pondered at some point or another.

But is it actually something that’s viable or that even makes sense?

Let’s find out.

Can You Stack Bookshelf Speakers?

Yes you can technically stack bookshelf speakers, though it’s generally not a great idea. While it may initially save space and even offer a volume boost of 6 decibels — interference, sound wave cancellation, even comb filtering/lobbing can occur. The exception is when dealing with 3D object based audio, since dedicated speaker modules should be placed atop front soundstage speakers.


Reasons Someone Would Want To Stack Bookshelf Speakers

To Save Space

One reason why someone may want to stack their speakers is they’re simply pressed for space.

Home theaters obviously vary in size since every room is different, but if there’s not a lot of space to work with, then you might feel the need to stack your speakers to save some space.

This of course depends on their size since doing this with say, a tower speaker, may not be realistic.


They Believe They’ll Get Better Output

Another reason someone may try to stack their speakers is they’re of the belief that because they’re using more speakers in tandem, that they’ll get better output overall.

Surprisingly that’s actually true, but we’ll touch on this aspect in a bit.

While I could see why someone would be tempted to do this, it doesn’t take into account the potential drawbacks it could cause.

More isn’t always better, and in this case, there may even be a few caveats to using them simultaneously in this way.


Where Did Idea Of Stacking Speakers Come From?

The earliest account of speakers being stacked came from a pair of speakers called the Large Advent Loudspeaker that many regard as one of the greatest speakers ever created.

Henry Kloss founded the Advent Corporations and launched the pair of loudspeakers  in 1969 with nearly instant feverish acclaim from the masses.

His original goal was to build a projection television however this eventually progressed into him developing the first pair of these iconic speakers (which would later be introduced in the smaller variant)

In spring of 1973, a publication called The Absolute Sound first talked about what became known as the Double Advent System.

This basically entailed stacking a pair of the speakers atop one another, tweeter to tweeter, as a way to enhance the overall sound quality.

This was something completely unheard of at the time, however this configuration would later go on to gain illustrious praise from audio publications & the public alike.

Even to this day, these are one of the very few speakers recommended as both a single pair and a stacked pair due to their impeccable sound quality.

These speakers are basically where the idea of stacking speakers comes from in a nutshell.

However unlike most speakers, these actually improved when used in doubles.


Are There Any Issues With Stacking Bookshelf Speakers?

So what happens when you actually decide to stack bookshelf speakers?

Well besides the fact that it’s definitely not something that’s recommended, you can run into all sorts of issues when it comes to the audio quality.



One such issue you might encounter is lobbing.

Lobbing is basically when the same sound arrives at the listener’s ears at slightly different times in close proximity to each other.

This can cause certain sound waves to cancel each other out while others get reinforced and peak.

So when you place a speaker on top of another, you lose varying levels of fidelity in the quality of the audio.


Comb Filtering

Comb filtering while similar to the lobbing, is basically how the listener perceives the sound at a certain axis.

Think of it like the result of lobbing.

Various wave cancellations and peaks cause the audio to seem uneven and distracting.

These dips in frequencies also resembles a comb on the frequency chart (hence the name)

When placing 2 speakers on top of one another, it’s likely you might experience some form of comb filtering depending on your room.


Worse Off Axis Performance

Similar to what what happens when you use 2 bookshelf speakers for a center speaker, stacking 2 speakers atop one another would give listeners off axis a generally worse experience.

Due to inconsistencies in the output, listeners off to the side would likely experience peaks and dips in volume that would really not provide a pleasant experience.

This would become more apparent in side sweeps when the sound pans from left to right, where you would almost notice holes in the sound.


Can You Avoid Problems With Stacking Speakers?

So with all of this being said, is there anything you can do to mitigate any of these problems.

Again I wouldn’t really recommend it, however if you’re determined to still try then there are a few things you should keep in mind.

One thing to remember is an old adage in speaker placement that certainly applies here.

The speed of sound divided by the center to center distance equals the highest frequency that both speakers should play together.

Placed at about 1/4 the wavelength distance, the speakers shouldn’t entirely cancel each other out.

In other words, taking the speed of sound in inches, and dividing that number by the distance between one driver on your bookshelf speaker and the other should give you an idea of what frequency you’ll run into issues.

The resulting number denotes this.

You could also place the top speaker upside down on the bottom one so that that waves aren’t interacting with each other negatively.

This special configuration, a D’Appolito configuration, helps to mitigate these pitfalls.


Is There Any Benefit To Stacking Speakers?

Surprisingly there is actually one benefit to stacking speakers that comes in the form of a volume boost.

In fact when placed together, there tends to be a 6 decibel volume boost that occurs.

However considering the actual quality of sound can degrade, it’s not really a worthy tradeoff.


Multidimensional Sound Through Speaker Modules

There is one application where speakers can be stacked and that’s when using speaker modules.

These modules are specialized speakers designed to sit on top of your front speakers.

Their primary purpose is to reflect sound waves off the walls to your ears to provide an almost 3D sound field around you.

They typically utilize object based sound formats like Dolby Atmos & DTS:X, and are a respectable substitute for actual ceiling affixed Atmos speakers.

The Klipsch R-41SA are a good pair in this case.


Final Thoughts

So to summarize, while you can technically stack speakers, it’s probably not a good idea.

You’re better off either substituting with larger speakers if your concern is proper volume output, or using an extra pair of height speakers angled downward towards the listening area.

But there’s always the off chance that it actually sounds decent so you’ll have to see how everything interacts with your particular room.

That’s all for now though.

Until next time, make it easy, keep it simple!

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