Plugging only one rear bass reflex port?

[Archsam]

You purchased the 105s from Nintronics? How were they to deal with?

They also sell the 106s for £999. Too much choice!

Just to follow up on Nintronics - I had to give them a second call this morning to chase up on the receipt, but having spoken to a nice lady the email arrived less than 5 minutes later. So all good and I will trust them if you decided to buy.

BTW too busy listen to music to take any more measurements will do so when I have more free time.

 

[Glasvegas]

Just to follow up on Nintronics - I had to give them a second call this morning to chase up on the receipt, but having spoken to a nice lady the email arrived less than 5 minutes later. So all good and I will trust them if you decided to buy.

BTW too busy listen to music to take any more measurements will do so when I have more free time.

Glad you got it sorted.

BTW, in one of your posts you noted that the port appears to be a cardboard tube painted black. Is that normal?

 

[Frank Dernie]

BTW, in one of your posts you noted that the port appears to be a cardboard tube painted black. Is that normal?

Yes.

 

[Rick Sykora]

Glad you got it sorted.

BTW, in one of your posts you noted that the port appears to be a cardboard tube painted black. Is that normal?

Yes, thicker cardboard tubes are easy to cut, have decent damping and glue nicely. Use them all the time.

 

[analogSurviver]

I saw earlier in this thread mentioned the use of the drinking straws in reflex ports. I have first seen such a port used by italian manufacturer CEMARK in early 80s.
https://melius.club/topic/211809-cemark-1/
https://melius.club/topic/302337-notizie-casse-cemark-mod-3/
At about the same time, Pro Ac used same/similar approch in Tablette. CEMARK succeded in obtaining a patent - commercial name IRROTAX. Those italian speakers have been quite decent indeed - and maybe I can still find the test results - measurements - from italian Suono back in the day. In the bass and particularly around the port resonant/tuning bfrequency, such ports that prevent turbulence actually measure far better for distortion than normal reflex ports. Even more than any objective mesurement s is convincing listening. A slow sweep from 20 Hz to 200 Hz is enough to cover any ported enclosure. At higher levels, normal ports produce so much higher harmonics to actually produce "vent noise" - an artefact never present in closed box. Ports using straws of varying diameter act much the same way a laminated core in transformer reduces eddy current and loss. Even at full output at the tuned frequency, "laminated" ports do not produce ( almost) any audible noise. That is in marked contrast to conventional port.
At the time, a friend bought Mission 770 - the first version, which was using a conventional port. I wrote to Mission how much these speakers can be improved trough the use of the straws in reflex tube a la IRROTAX. They never replied... - at least not in a letter. Yet, please google "Mission 770 Freedom" - which came to the market about half a year later following my letter .
Here Mission used a MUCH larger diameter "straws" - the reason being that reflex port achieves its damping trough surface. And normal straws really increase this surface who knows how many times compared to conventional empty tube - creating an overdamped system. This is the reason Mission went with as large diameter tube straws as possible - still enough "lamination" to prevent vent noise, but not way too much increased vent surface and thus damping.
For those more interested, please check Speaker Builder magazine - tons of material on ported designs.
And, as has been clearly demonstrated in this thread, "de-tuning" a reflex port can actually improve the performance in real world room. One could experiment with IRROTAX port tube to get both better frequency response as well as much lower distortion.
This is perhaps the only time at least an audiophile might regret banning the plastic straws - and indulge in "illegal" activities as far as 2020 is concerned.

 

[Vini darko]

I'm using the sock method to reduce port velocity. Works great.

 

[daftcombo]

Seems like plugging a port can sometimes extend bass?

https://community.klipsch.com/index.php?/topic/183624-plugging-rear-speaker-ports/
(with measurements)

 

[Duke]

Seems like plugging a port can sometimes extend bass?

https://community.klipsch.com/index.php?/topic/183624-plugging-rear-speaker-ports/
(with measurements)

Plugging one port (out of two) shifts the tuning frequency downward by about half an octave. So the region where the port is reinforcing the strongest is correspondingly moved downward in frequency - note the reduced output north of 32 Hz with the ports plugged (which happens to be desirable in this case, but is not always).

In the example at that link, speaker +room summed to a flatter and deeper response with one port plugged two out of three ports plugged, which lowers the tuning frequency by ballpark 7/8 of an octave. Definite improvement in that case, assuming adequate port area to prevent chuffing.

If the speaker was getting significantly less boundary reinforcement then all ports open would be the better configuration, as ports plugged would be too lean.