Front Ported v. Rear Ported Speakers

What is the functional difference between these designs? Thank you in advance/
You can place the front ported speaker closer to the rear wall.
Read This!
If I plug the ports on a ported speaker, will that change the sound characteristics to be more like that of a sealed box? Or is it not advisable because of all the other design considerations, i.e. cabinet shape, crossover, woofer attachment and etc.?

This kind of makes sense now that I think about it. These trade offs must have been at the heart (or close to it) of the design philosophy of M&K; sealed boxes in combination with a sub and bass management. Perhaps it isn't surprising that my search of a replacement for my S-85s includes the NHT Classic Three, also a sealed box.

Don_c55, thanks for posting the link.
FWIW, I plugged my ports (EgglestonWorks Fontaines, dual rear ports) and raised the crossover points on my subs. It did seem to improve the clarity of the upper mids and HFs somewhat, but I lost too much of the "meat" of the sound to keep them this way. After all, they were specifically designed to operate with open ports. I suspect any critically designed speaker with ports would sound better left open, as intended. My unscientific $.02. As always, try it yourself and see. It is a free and easily reversed tweak, unless you stuff too far and your socks (or whatever) fall inside.
Thanks Rockadanny for sharing your experience. I think I might give it a try and play around with plugging the ports. I think I'm also going to purchase a couple room treatment panels and play around with them too.
In general, front ports should do better closer to walls in theory, but a lot regarding best sound in any case depends on room acoustics and other factors case by case. So its quite possible in some cases rear porting could work best.

The most common truism about speakers is that soundstage depth is almost inevitably compromised when placed closer to the front wall. Second most common is that bass levels will usually be higher as well.

So you can see that specifics case by case will determine what works best, even if certain general trends apply.

Also most good ported speakers are designed to work best in general with ports open to extent designed, but again, obstructing port to various degrees can be a useful tweak in some cases nonetheless.

BEst to make decisions based on what you or some other knowledgable resource most familiar with your situation thinks, will work best in general, but be prepared to think our of the box as needed from there in order to get best results.
My first prototype speakers were front-ported, but I switched to rear-ported. Here's why:

1) If unwanted midrange energy emerges from the ports, it will be farthest possible from the listener, and thus less likely to be audible.

2) It is desirable to spread out the low-frequency sources as much as is feasible in as many dimensions as possible. With a rear-facing port that's at a different height from the woofer cone, once the speaker is toed-in, the two low-frequency sources (woofer and port) are at a different distance from the room boundaries in all three dimensions.

3) If port-plugging is an option, we have less visual disturbance if the port is on the back.

4) If a rear-facing port is tuned with boundary reinforcement in mind, there is no detriment from its being on the rear of the cabinet. Audio Note proved this; my imitation of their approach is sincere flattery.

I recall one time delivering a pair of rear-ported speakers to a customer. They replaced a pair of well-respected front-ported transmission line speakers. One of the first things the new owner commented on was that the in-room bass was smoother. I think this is because, with the speakers toed-in as recommended, the room-mode-smoothing effect of staggering the bass sources in all three dimensions had enough of an influence to be audible.

I love the way Duke thinks.

Damn, I would love to hear a pair of his speakers someday!
Duke has acquired a lot of knowledge over the years that he has judiciously applied to his speaker designs. I find my Jazz Modules offer all the benefits of the Audio Note AN-E speakers I once lusted after without the disadvantages, namely having to place the speakers close to the wall. I have never had a problem setting up my speakers and getting a very smooth bass response or even tonal balance going on 6 years and 3 rooms.

Attending and exhibiting at audio shows has allowed me to listen to some highly acclaimed [and high priced] speakers. I have even fallen for a couple, like the Cessaro horns I just heard at CES. However, when I get home and listen to the music pouring out of my Jazz Modules I realize life is not so bad and my speakers more than hold their own, at a fraction of the cost.

Disclaimer, first a happy customer, now a proud dealer for Audiokinesis.
There are too many design issues making major contributions to the quality of sound, or lack thereof, to fixate on the port position and gain any insight of how the speaker will sound. Listen to music on the speaker, don't prejudge it by one aspect like port position.
Agree with Kidman.

Duke is a fantastic out of the box thinker, especially when it comes to considering dispersion and soundstage related design considerations, delivering value, and other things, and an exception, but I do think that in general most rear ported speakers are designed to work best in genral further away from the front wall whereas most front ported or sealed designs tend to work better closer to front wall.

So worth keeping in mind, but not a hard rule that will always prove true.

Bass response will be a big determining factor. Proximity to walls in most cases results to more bass re-inforcement regardless of design.

Distance to walls in general helps with soundstage and imaging. How much will vary depending on many factors, dispersion characteristics being one of the bigger determining factors.

Most every speaker will sound different close to front wall versus further away. Which is better depends...on a lot of things. GOtta listen and compare to know for sure in each case. Always be willing to tweak and change something when needed. What changes need not always be the gear itself.