Bass reflex port placement
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- เผยแพร่เมื่อ 2 ก.ค. 2022
- Is port placement important? If so, where exactly do we place it?
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Something I’ve always wondered but never seen tested, fantastic! I’ve seen a few of your videos randomly before but am now subbed👍🏼
Excellent video and info! Thank you.
chestii foarte utile pe canalulñ tau , raspunsuri la intrebari care chiar mi le puneamsau video cu vatelina( dampening material) la care ma gandeam ca e un mit, si cand eram mai tanar faceam tot felul de teste cu boxe de exmplu in loc de vatelina puneam polipropilen ( zapada ) chestia aia de la pachete si mi se parea ca are mai mult bass dar de fapt cred ca rasuna mai mult cutia. multumim pentru clipuri .
I can definitely hear the differences you mentioned in the speakers as far as the depth of sound field etc like they need to be in the room to tell that. But as far as the differences in a female voice, the hi-hat and the different sound of the drum, I can't definitely tell the difference
I have 2 18’s in my truck and I placed the port near the roof in the middle of the 2 seats, perfectly square port which is better than a long rectangle. 4th order bandpass
This was a good video, something ive wondered about.
It would interesting to look at port placement effects just on the front of TABAQ and Pensil type enclosure designs. These are tall, vented, enclosures with small cross sections made for 3" drivers where the speaker driver is at the top front and the port at the bottom front of the cabinet. They're almost like transmission lines and I suspect that there is a "false bass" peaking from 100 - 200 hz. Most current 3" drivers have an fs around 100 hz.
Great video, very well explained and answering exactly my question! Thanks a lot I suscribed :)
Great video been wondering about this. I am curious though about the effects of ports placed so the they fire across the face of the driver. I believed JL Audio makes one and I just saw a Gately Audio box with dual ports facing each other across the driver front. I know this would be an advanced design but would be interesting to see if there’s any advantages to it.
wow, great work. thank you very much :)
Nice box, any advantage or drawbacks to having ports facing across the woofer front?
Great one 👍
Also can u consider making a Ripole sub and a dual driver push push or push pull in subs
Cool video and channel! Subscribed!
There's a trick with standing waves that can be used to minimize the problem with port resonance. Basically you need to design the box in such way that the mouth of the port is located around a null of a standing wave that is created inside the box. The standing wave must be of the same frequency as the port self resonance freqency. I want to try it out in the future with a small full range speaker. The problem is that WinISD seems to miscalculate the port lengh and with it the port self resonance frequency.
Or a large bottom port. Basically negating most standing waves in towers, and adding to port gain depending on the height off the floor
@@Luke-qs2cg this is true you want the mouth of the port as far away from the driver as possible so the box can build pressure as the wave builds you don't want the mouth of the port right up next to the driver
@@johnnycorn7225 Generally I agree. Only one thing bothers me - port near the floor will have floor gain, can cause acoustic problems in the room like rumbling floor (depending on the flooring material) and overall incorrect boomy low freq response. Same as if we put rear ported speaker close to the wall.
@@johnnycorn7225 I dont know if you just poorly worded a certain phenomenon, but what you said sounds like bro-science
@@KompletterGeist it's really straightforward, just keep in mind I'm talking about the opening of the port on the inside of the box being as far away from the driver as possible.
The reason this is desirable is because you definitely will lose pressure if you have the ports opening too close to the driver, and that means less air flow coming out of the port and less bass.
Nothing too technical or scientific about it check out buck box designs he talks about this topic in depth.
I've been building boxes for a long time and have observed this personally.
Wait wait wait +1db gain is insignificant? A 3db gain is equivalent to a doubling of input power.
Not to mention your first measurement comparison had a lower -3db rolloff point in addition to that +1db in output, making it significantly superior.
Wich better ?
Im confused so a rear port will result in box loss?
great and awesome video! what about a port on the bottom…with proper gap btwn port and floor?
That will work. Many manufacturers opt for that placement.
does the frequency of the standing wave move up if the box is shorter? do you know the relationship between the standing wave and the height of the box, like a full wave, 1/2, or 1/4 waveleingth? thanks
I have questionable Design Idea for my car, listen...
I have a BMW E36 Sedan, the problem is, i cant just put in a ported sub that plays into the trunk because the trunk is closed of, the back seats are mounted on a solid back plate out auf aluminum.
I have a ski back wich is pretty small... So my Idea is to build a box with the port extending out of the box going OVER the Subwoofer driver itself... do you think it will work? The only other ways to build a box for this car is either a bandpass (wich i really do not want, because it will be more complex and bandpass most of the time does not sound as good as ported or closed) or a closed box with the driver sitting behind the ski bag wich I dont want either, but consider it more if ported wont work. Should i just try?
you're awesome
Thanks for the great video
Can u make a video how to measure example at 9.13 how to measure this. I have umik mic but don’t understand for to use it
take his course on Udemy
Missleading. Re-measure your floor stander, but not at nearfield. Just put it down in your room , close to a wall. Put the mic at a reasonable listener position .
Now we can talk.
1. Behind the magnet, not a good place . At higher volume you will have more port noise.
2. Difference between forward and rear firing comes from the effect of the wall behind. Basicly you can modell that as if your port would flange out drasticly.
3. Yess I em aware that this is mosly room accoustics. Argue about it only, if you listen to music keeping your ears kept at near field.
Same goes for down firing ports. They get an extention with a huge flare.
Backward and forward firing allso has phase differences at the listener position. Hence nearfield will show nothing out of that at all ever.
In a car sub it makes next to no difference , as long as the port is not choked. That is correct. The rest you say is invalid. And can be with ease tested with the setup i described.
Allso about standing waves... look , it exsists in subs too , and whit all speakers. Ever. No excuse. What you can indeed do when designing is avoiding sqaure shapes. Not ideal but you could set up your dimensions to give the desired volume , and having a ratio of the thrid root of 2 vs each other.
So A side internal is say 1 unit ,
B side internal is approx 1.256*A
C side internal is approx 1.256*B
Thatway at least the resonants will not share a harmonic and not add up.
A nother oldschool solution is to suspend in the middle of the box somen spongy dampening material. Make sure the string you use is some wool of othet type that makes no sharp sound. That will break the path of the standing wave , and allso absorb reflections.
Just some old school 60's era advice .
Would not a typical 24 db/octave low pass XO @ say 80Hz mitigate the standing wave issue or is that a natural harmonic that can't be filtered out?
It would filter the standing wave, but then you wouldn't have any midrange. It's not a subwoofer it's a mid-bass driver.
@@AudioJudgement I see. It never occurred to me that was the goal here. With a port tuning in the 30's it seemed fitting for subwoofer performance. Isn't midbass in the 80 to 400 Hz range?
There is any problem to install passive radiator which is 2 inch smaller than woofer?
Rule of thumb: displacement of pr = 2 * displacement of speaker. So the surface area * xmax of the passive radiator must be atleast twice the surface area * xmax of the speaker.
i need your help how can i send to u the pic of my box it have 2subwoofer 12 inch and tell me where i put the port and its diamter??
I have listened that sub up port back works, anyway It is not that loud the port but in a good car aucustic model like new cars 2010 and up, port and subwoofer same panel awsome
What about on top of the box? For stereo speaker gives an extra "surround".
What are the dimensions of your box and port?
Watch his video on making a speaker with only two tools.
Hi, nice video it really help me a lot but i have a question. I am building a bookshelf speaker with bass reflex box. My problem is because the speaker and space i have, and also because in my country there is no many places to buy ports i was thinking in 3D printing my own port with my customs needs. It is okey or i have to take care of something. Thanks for all!
You can just use a rectangular port. And make from whatever material you are using to make the box.
Oi, Marius. Nice to see you again. Have you read your mail past three mounth? I've send you one about some awesome discovery in crossover building i've made. Check it and lets have a talk (: