Plugging rear ports of "bookshelf" speakers?

You are correct..Many ported speakers get a bloated,boomy bass when moved close to a rear wall..Plugging the port creates a quasi sealed enclosure,reducing bass output..

...and potentially altering its intended sonic signature. 

Hence why I prefer sealed designs. Easy to place them in my bedroom system- I put my ATC 7’s on cork and rubber feet directly on my 72” low dresser about a foot from the wall, and they image really well with no bloat in the bass.

Think of plugging a port as a tuning option.  The options lets achieve good bass in a variety of situations compared to a speaker that did not have a port.

@noromance is correct, you ARE altering it's sonic signature so that it sounds better in whatever location you place it in. 

Speakers aren't golden cows to be worshiped and rotate our lives around them.  If you need a speaker on a bookshelf and it sounds better plugged then do that. 

@erik_squires +1

Exactly. Speakers + Room = most of the acoustics. Optimize both and you optimist the situation.

@immatthewj 

If the speakers came with plugs (e.g. many KEF models) they are designed to be plugged so that the sound will be more balanced when you place them closer to the wall.  The KEF LS50 for example has three modes- open port, half plugged and fully plugged.  The manual specifies the best position from the wall for each mode.  More plugged = closer to wall.  

However many ported speakers are not designed to have them plugged.  Woofer suspensions are such that they can be designed for stiffness / wide open port, hybrid stiffness where they can be both ported and plugged, or very loose suspensions that require them to be sealed.  

First step is to consult your manual to see how close they recommend placing them.  You can always experiment by plugging the ports.  I tried it once with speakers not designed to be plugged and it ruined the whole sound and distorted the midrange.  

Recently bought a pair of Ascend Sierra 1 bookshelves and then bought their brand port plugs, one set open and one closed.  Need to play around with them to find the best sound....they are quite small speakers but so far are pretty impressive....driven by NAD C 375BEE.....

The New EPOS Loudspeaker model ES-7N which was released in May 2024, has the feature of a switch on the back of each speaker to allow for near-wall  or free-space placement. The EPOS Loudspeaker line-up were designed by Karl-Heinz Fink, the owner of EPOS Loudpseakers and Fink Team - currently two EPOS models available with a third model to be shipping in September 2024. The ES-7N, the smallest model in the EPOS brand, can be purchased with much less concern over speaker location. EPOS is a very well thought-out speaker brand.

The reason for plugging port is the port can muddy the bass. A bass note is first sent out the front of the speaker then a delayed signal is sent out the rear port, hits the wall and arriving slightly later to the listener. The port is also 'tuned' to add a bloat sound at a certain frequency. Much like blowing air into a wine bottle and can be tuned higher or lower depending on volume or length. A cheap way to produce bass.

It's important to understand that if you seal the rear port completely (plugged) the excursion of the driver will be negatively affected. THIS IS NOT GOOD! This imparts a restriction on the driver and reduces the overall output of the speaker including the upper bass region. Even foam plugs or socks stuffed in the port will reduce excursion. 

An old method that lets the speaker breathe is placing a bundle of straws in the port. It disrupts the tuning of the port so the cheap sounding 'one note bloat' is eliminated yet still allows for full excursion.

If you then properly integrate a subwoofer the low bass should be greatly improved. 

@avanti1960 +10

Mike

A rolled up sock is a good place to start….

I think taping a kazoo in each port is the way to go.

...then play "Romantic Mouth Harp Hits"...

Thanks for all the great input, @everybody.  The speakers did come with plugs, and for last night's session I did install them.  As per usual, I am not sure which way I like better, but I am thinking, so far, that I prefer them plugged.  Since they arev plugged, I guess I could experiment with moving them closer to the untreated wall?  The face of the speakers is at 25" presently.  Is there anything to be gained by moving them closer, besides making my small room incrementally bigger?

"Bookshelf speakers" and "too much bass" do not often exist simultaneously.

Jerry

"Bookshelf speakers" and "too much bass" do not often exist simultaneously.

"Too much" was probably not what I meant when I typed "unruly bass," @carlsbad2  .  Also, it's not that they are on a bookshelf, maybe I shouldn't have called them that.  They are 2 way monitors; regardless, you are right--they are not guilty of too much bass.

Generally proximity to the wall will cause a loss of perceived depth of the soundstage that good monitors can provide, so you gain yourself some bass at the expense of imaging.

kn

I suggest you another metod. I did it myself. 

My bookshelves don't have rear ports, instead they have passive radioators (Buchardt S400 MKII, very bassy speakers), but it doesn't mean they can be placed close to the wall, it's a bad idea.

I placed behind the speakers Basotect panels, very effective sound-absorbing porous material, and sound increased amazingly, bass became cleaner, punchy and heavy. But anyway the speakers should stand 40-50 sm from the wall.