FAQ: DTS:X Blu-ray Compatibility, Ported and Stacking Speakers

[gene]

As you could imagine, we get bombarded with questions from our reader of the site. While we can't always answer all of the emails in a timely manner, we do try to occasionally formerly answer the ones that seem most relevant to our readers in the form of an FAQ. In this FAQ, we answer questions asked by various readers about DTS:X Blu-ray compatibility, the differences between front vs rear ported speakers and the issues of speaker stacking and whether or not it should be done.

Discuss "FAQ: DTS:X Blu-ray Compatibility, Ported and Stacking Speakers" here. Read the article.

 

[Motrek]

I don't really understand the sound that comes out of a port. It seems like it can't possibly be in sync with the sound that's produced by the drivers, right? In which case it seems like you'd want to hear as little sound from the port as possible, and that means it's better for a speaker to be rear-ported, because you would hear the sound from it that much less. Please correct me if I'm wrong.

 

[Schurkey]

I don't really understand the sound that comes out of a port. It seems like it can't possibly be in sync with the sound that's produced by the drivers, right? In which case it seems like you'd want to hear as little sound from the port as possible, and that means it's better for a speaker to be rear-ported, because you would hear the sound from it that much less. Please correct me if I'm wrong.

You're not entirely wrong. Ported speakers--including the passive-radiator (PR) variation--go progressively out-of-phase as the port or PR takes over from the active drivers.

The question is whether we can hear this progressive phase problem; and if we "can" hear it, do we notice it?

First Guess: The phase problem is not especially important.

Second Guess: Some folks may be more sensitive to it than others. Like many other audio system faults, I suppose it's something that an educated/trained listener could hear, but I have no idea how a person could actively train themselves to perceive this.

Third Guess: The frequency-response degradation of plugging the port is FAR more noticeable than the phase degradation caused by the functioning port or PR.

With ports tending toward the bass end of the frequency spectrum, and bass tending to be more-or-less omnidirectional, the location of the port or PR makes less difference than a person might expect. Of course, speaker location and room treatment will have some effect--as it always does.

 

[-Jim-]

Gene,

Thanks for the opening remarks on Ported Speakers as it's amazingly timely for my situation.

Actually the "typical" ported speak shown, the Pioneer SP-BS22-LR, is the main focus for me right now. I have a home office, and do about half (sometimes more) of my workdays there. So, over time, I've been making it more comfortable by improving the sound. Originally it was just me and a Laptop with it's small tiny speakers, then onto headphones => but they made it tough to answer the telephone, so then onto discrete Speakers.

Anyway, with a little mad money, based on the overwhelmingly positive reviews I read, I recently bought a pair of Andrew Jones designed Pioneer SP-BS22-LRs which replaced some front ported speakers that I had hanging on the wall in the corners on either side of a nice large window. (My desk sits in front of all of this.) I didn't realise these Pioneers didn't have any way to mount them onto the wall, so I borrowed the brackets off the old Speakers. It wasn't until after I hung them that the light bulb went on about them being rear ported.

I did consider putting them onto my Desk, but to get them to ear height would be tricky as well, as I really didn't want them to be "that" close. (Near Field is not for me!) I considered Speaker Stands but decided to check out some speaker mounting brackets.

I ended up getting some Pyramid 4090 Hang Speaker Brackets off eBay last week for a song. I don't have them in hand yet, as there was free shipping to the lower 48 and I'm in Metro Vancouver, Canada. My Mom lives 5 minutes away from the Border, and she's picked them up from a Mail Drop (she goes across for Gas, some groceries, etc., - but a little less so now with the Canadian Dollar in the tank...) She's coming over for dinner this Sunday (Mother's Day!) and will bring the brackets with her.

Hopefully they'll do the job, and I'll hear an improvement. What do you think?

Regards,

Jim

 

[Swerd]

Speaker ports can generate some noise due to air turbulence. It usually requires high volume to hear it, and this is why most ported speakers come with the port on the back. You are much less likely to hear it that way.

Pioneer SP-BS22-LRs were reviewed by Stereophile, http://www.stereophile.com/content/pioneer-sp-bs22-lr-loudspeaker-measurements.

Their measurements show the woofer's output (blue), the port's output (red), and the summed woofer & port outputs (black). Most of the port's output is centered around the woofer's resonance frequency (about 70 Hz) where it moves the least. You can see the port's turbulence noise between 500 and 600 Hz and higher (their port measurements don't go above 1000 Hz). It's much quieter than the sound from the woofer, down by 25 dB or more, so its unlikely you'd hear that.