What is the best Port size?

In this video I go through what port size is best and why, and how to design a box around it.
TIMESTAMPS:
0:00 Introduction
1:00 - Problems with small ports
3:35 - Problems with big ports
4:46 - Conclusion
6:30 - Sources
7:21 - Discussion

[@Dakoustics]

If you wanna know what LENGTH your port should have, check out: "What is the best Port length?" kzbin.info/www/bejne/iHWodqBjf7xqn8U

[@lamarcuskennedy5974]

Thank you lol 🙏🏾

[@staLkerhu]

Dude, something is completely off here... with that calculation, a tiny *ss box with 5,45L would need a 5cm port in diameter, which makes 0 sense. What makes even LESS sense, is a 6,8cm port would match with a 10L box, while both the industry and knowledgeable DIY builders use a singular one of that size for 30+ L boxes. I don't buy this.............

[@bournelucid]

Finally the youtube algorithm suggest something i WANT to see

[@Dakoustics]

heh cheers

[@nuclearbum9858]

this is a good video

[@KevinWilliams-pi6fc]

Lol. Yup

[@surajkale1143]

😂😂😂

[@jblfreak4294]

Bro I had to look this shit up

[@jeffgreen8496]

I only watched a few of your videos yet, but so far i love them. I love how u break things down and go into depth on subjects. It really has taught me alot. Keep the videos comming and I will keep watching. Thanks for all the advice.

[@billthebass6326]

Found this video while trying to tune the port on my 2x10 Ampeg (copy) bass cabinet, 50L. Did the math, it sounds spot on. Thanks!

[@fredygump5578]

I built a 100L sub tuned to 20hz, and used a 9.9cm/ 3.875" diameter port. Then I built a second version using 2 ports that were the same 9.9cm diameter. Comparing the two, the single port design had noticeable low frequency compression @80dB+, and the THD measurement showed a peak of 10%+ from 20-30hz. The 2 port design had no compression at 80dB, and THD was 2% at 80dB. (The sub is built into a full range floor standing speaker, so I have vertical height for tubes the full length of the port.)

[@jasonneal]

The information here has been proven over and over and never fails. I’ve seen videos of these kids with these new subs with higher power and they think they need a bigger port.

[@dontrustwhiteyevery1]

Depending on the subwoofer.

[@jasonneal]

kilamanjaro Mountain yeah, not by much though. The Thiel small parameters are different from sub to sub, but as far as the box size to port size is minimal. Certain subs play better in different box tuning but for the most of it you build a box for 2 12” subs with box volume 4.25 with a slotted port of 16W/3H/22L you will be in the ballpark of a tuning of 32HZ give or take a frequency or 2.

[@dillonkoch72]

I have one DS12 EVL. In a 2.7c box I want another one though. What's the best ported box for spl I can make. ?

[@jasonneal]

Mark Godfrey it’s not the port size to the sub, it’s the box size. He even showed that 2 different manufacturers are using the same formula.

[@jasonneal]

Mark Godfrey exactly. Certain subs perform in different size boxes than others, but the formula for port area is the same

[@bradleyhauraki4965]

Finally something I actually want to watch.. Thank you

[@DJSNT]

Below are some notes I would like to make. I'm aware it is essentially a novel in length, but when you're passionate about a hobby that is just what happens. lol 1.) Xmax is normally a figure of one-way travel, not Peak-to-Peak, also not to be confused with Xmech for those who are curious. 2.) The ports themselves shouldn't generate 'wind' (Air Flow) or essentially displace air from the port volume, it usually occurs below fundamental tuning due to the rise in velocity prior to the reduction after once you've extended well below fundamental tuning. Rather the most idealistic scenario is limiting vent velocity so that the column of air within the port resonates with minimal surface/ cross-sectional area resistance which would cause turbulence. 3.) Port Area's relation to Resonance is correct, though what is largely important is driver selection, this will be covered after the next statement. There is a caveat here, where you move into the B.V.R. [Big Vent Reflex] territory. This is a hybrid between a Bass Reflex, and Quarter Wave Pipe where you're coupling the net volume, chamber length, port volume, and port length for the fundamental tuning which if done correctly will significantly increase damping apposed to an average net volume and less lengthy port than a BVR. Within Horn Response, you can view the Impulse Response, or export the Impulse Response to a .Wav file and make an audible comparison between enclosure adjustments to get a rough idea for Impulse attack, sustain, decay and release. Prior to doing so, it is best to use the Filter Wizard to set the theoretical subsonic filter and low pass filter to get a more accurate representation of the transient response. Back to the statement about driver selection mention prior. The drivers' damping factor is incredibly important for more accurate transient response achieving less of a muddy/ boomy response near tuning, though a note to make is that you have to also account for Lossy Inductance [Lossy Le] which for most mobile audio drivers impact them heavily having a rather high Le:Re ratio. The higher the inductance is in relation to the Impedance of the driver the more resonant the driver will become due to the back EMF generated by the coil. Though, 'most' Home Audio, and Professional Audio drivers feature shorting rings, pole sleeves, bifilar winding types for the coil and/or non-conductive coil formers to limit the amount of inductance present. 4.) Though a suggested 'Golden Rule' for In² per Ft³ isn't a bad start, if the program used to simulate/ design the enclosure is capable of it, keeping tabs on Group Delay, Vent Velocity, and Diaphram Displacement, keeping each as low as possible while maintaining a more linear acoustic power profile is most ideal for most applications outside of SPL. As an addendum on the topic relating back to Lossy Inductance, this will shift most mobile audio drivers largely off of what would be optimal without taking it into consideration. It isn't a perfect method but has been measured via RTA in 1/2 Space Radiation in comparison to the simulated result and from our findings, it closely follows the trace with Lossy Inductance calculated. With the additional driver resonance, the enclosure usually has to sacrifice its smaller footprint to increase the net volume, counteracting the peak above fundamental tuning that is caused by the abundance of driver resonance. This also makes many drivers fall outside of the acceptable EBP region to be 'ideal' for a bass reflex alignment, and for those shooting for a 0.707 Qtc Sealed enclosure, it can actually be impossible in some cases. Just here to clarify a few things and present some ideas that most are not aware of. I'm not trying to step on any toes, just explaining what I've gathered over the years since I have been pushing to learn as much as possible within the acoustic engineering field. At the very least it'll steer those who are less technically inclined in the right direction not to overshoot or undershoot port area either because they aren't aware of the effects, or they've been told by others to do one way or the other and end up with poor results. So for that, thank you.

[@THESUBZILLA]

DJ Slow N Throw damn what language is that!? Lol I hope I will know what your talking about one day. I’m learning as much as I can. But I love your music btw!

[@ilfaraone91]

This proves that making rebassed musinc is not as simple as it looks,you have to know every single aspect of both the driver and the enclosure. A great lesson from djsnt!

[@Hertzsogood219]

Love it DJSNT!! A comment just as accurate as his beats!

[@DJSNT]

@@THESUBZILLA Just the language of a passionate audio enthusiast. The reason music hasn't been coming out is that I'm sufficiently enthralled in enclosure engineering as Subsonic Center Enclosure Engineering. I have been producing music in the background though, should have some new videos in the future.

[@THESUBZILLA]

@@DJSNT Wow, that's awesome!! are you gonna start a box design business?! also is there a website I can find your rebassed/slowed music aswell?

[@Patata0ke]

ported enclosure sounds good on bigger speakers but I always like the passive radiators in motion also it only need less box size.

[@si12volt1]

yes there's a math to the correct port size .. I owned a custom car stereo business back in 80s 90s we built hundreds of sub boxes we called it tuning the box ..the port is crucial to the specs of the box and cubic internal air space also is crucial also depending on the speaker used

[@berniemackattack86]

You sound like you know what you are talking about bro.. Would u recommend pairing the JBL S2 1224 subwoofer with the GS PT 112 Ground shaker Box- slanted ported ?

[@CrashPCcz]

Heya. Valuable info. The technology came forward a lot, and nowadays if you know what you´re doing, and use high end drivers, you can use the port very differently. No need to optimize the port itself for best accoustical performance anymore. Golden ages. Now I can afford to optimize the port for impedance shape, for cooling, Group Delay and transient response (boomyness) and such. It is great helper to make efficient compact system now, instead of desperate need for speaker to produce any SPL at the bas region. That way I can afford to put a 21" speaker into compact 230l box, measuring 58x58x76cm including feet, handle and 100mm casters, load two into european sized car, and make quite loud gig for 150-200 people. Hope IPAL and M-force technology comes forward some more, so we increase the power density even more.

[@Dakoustics]

Yeah, M-Force looks really cool, though from what I've found its quite expensive. Would be cool to see more companies adopt a moving magnet/stationary coil system.

[@bujoun76]

This video is infinitely easier to follow than the others. Thanks!

[@seventhquarter]

... definitely one of those critical aspects, often overlooked in DIY's...

[@easternfloridacaraudio4578]

Very accurate, great detail and description. Good video bro. Keep it up.

[@ebiros2]

Below the tuning frequency, ported system acts like open back enclosure. To maintain some back pressure on the driver I find keeping port area to be 1/4 to 1/8 of the driver cone area works the best. Of course there're systems like Altec A7 where port is much bigger than the driver ( but driver has reasonably stiff suspension that supports the driver cone )

[@1-Six-dee]

I think it all depends on your goals ur driver and vehicle, if u r firing into an open cabin jt will vary then if u have it dead against a back gate

[@ASSOpid]

Yup people always forget about the vehicle which itself is an enclosure. So you should tune your box to the vehicle size.

[@Creator_Veeto_PAEACP]

@@ASSOpid finally someone mentioned it.

[@joserefe5950]

To eliminate all the above problems use a sealed baffle.

[@v3Gamingg]

can you make a video on how to design a subwoofer box?

[@KrishnaKrishna-bj7nf]

i would like to see experimentation with adjustable port size to demonstrate it, with various musics and tones. Great Video, and thank you kindly.🌺

[@CooperateMind]

Actually WinISD shows the air speed at different frequencies so you can change the diameter and check the speed so no more calculations is needed

[@Rastapapulus]

4:22 Mmmmmm~~~~~ Thank you man, I really enjoy the video. highly appreciated.

[@BaddDukk]

The primary issue with using a ratio of vent area to box volume is that it ignores the volume displacement of the cone. It doesn't take a lot of thought to see that a 6.5" woofer and a 10" woofer in the same 1cuft box might require different diameter vents. Even if driver diameter is kept constant, Xmax varies wildly from driver to driver, also affecting the total volume displaced by the cone. A better calculation would be Sv = 0.02032* Fb * Vd where Sv is the vent area in square inches, Fb is the vent tuning frequency (yes it actually makes a difference what the tuning frequency is) and Vd is the volume displaced by the cone in cubic inches (Sd x Xmax). 0.02032 is a constant that will result in a vent area to keep air speed in the vent to ~ 5% mach, or about 57feet/second. This is good for a quiet environment like in a house. In a car, and especially one where the enclosure is in a trunk, higher speeds (more chuff) can be tolerated but should not exceed about 9%mach (100fps).

[@Dakoustics]

Ah, nice to see some algebra in an example. I've had theories tuning frequency affected vent diameter, though not seeing solid examples elsewhere online. One thing to note, is tuning chokes the driver, and makes it much more difficult for it to reach Xmax at standard power, although the 0.02032 may already consider that.

[@thumpy662]

Very good video. I tend to like 12 to 13 sq" of port space when I'm tuning for deep bass 29 to 32 hz. If I'm tuning a little higher I'll shoot for 14 to 15 sq". But to each their own. It's a matter of what works for you. And just to help those out that don't know you just simply multiply width times the height of your port to get the square inch of it. If you want 12sq " of port space for example you will have a 3 inch wide by 4 inch tall port if you had 1 cubic inch of airspace in your box.

[@satishvasane6812]

Thanks brother from India

[@JaMarvelousjmar]

I've gone by the enclosure volume to determine port area but I've heard about using cone displacement as well to calculate it as well. Both can be applied and I think it all boils down to the application and skill level.

[@BARBELLS-AND-BUDS]

I've heard cone area for 4th order port area

[@FSXgta]

If you use WinISD or any other program that can estimate port velocity, try to keep it under 30 m/s (100 ft/s)

[@marthax.korver3401]

100 ft/sec is much too high! It should be no more than about 55 ft/sec. Port compression occurs well befor chuffing becomes evident.

[@FSXgta]

@@marthax.korver3401 for most people I doub't it will be a problem. Could you perhaps show some tests?

[@Grommet2007]

@@FSXgta Some actual tests.... facebook.com/DIYRM/posts/1212863525554986?hc_location=ufi

[@TimpBizkit]

I designed ported and 6th order bandpass and for a full power signal at tuning, the port velocity is usually around 25-30m/s but it will rarely see this value on music. It's basically the lowest value I could get with reasonable sized ports that fit in the box for the tunings I want. I also prefer to have port lengths and box depths less than a quarter wave of the highest frequency of the subwoofer to avoid organ pipe and back wall response anomalies.

[@Grommet2007]

For subwoofer duty, when you consider the capabilities of today's drivers, it's difficult to stick to that 1/4 wave limit and still use vent vents that are large enough to reduce compression and chuffing within the driver's linear capabilities. This is why I've shifted to using offset TLs instead of simple vented designs because with that type of design I have a lot more control over the impact of those 1/4 wave resonances. I haven't designed or built a bandpass design in a while, but the last one that I retuned was able to minimize the impact of the first 1/4 wave resonance, the result was a build that had the out of band noise around 15dB below the passband.

[@halweilbrenner9926]

I got amazing results by mounting a full range 4 ohm 5" dia. speaker in a thick cardboard tube fully sealed. Powered by a 5 watts per channel 8 track tape deck (Muntz brand).

[@kostasbeverly9713]

καλησπέρα σας να σας κάνω μία ερώτηση αν το μεγάφωνο των τοποθετούσατε ανάποδα ο μαγνήτης έξω από την κούτα είναι σωστό ή λάθος ....ευχαριστώ πολύ εκ των προτέρων

[@djijspeakerguy4628]

I have noticed this. I had a Yamaha surround speaker with two tiny ports, less than an inch wide, and 2 inches long. It had a 4 inch woofer. The issue: not tuned well. Muddy sound, port chuffing. The ports are literally cardboard tubes glued to the front particle board panel, so the ports even have a little lip on them that is smaller around than the port itself, which just makes it worse. Same thing with many Onkyo surrounds. Funny thing is, the ports on the speakers from many of the cheap “all in one units” mini stereo systems from the 90s and early 2000s (Sony, Aiwa, Jvc, etc.) are actually tuned extremely well!

[@Dakoustics]

Yeah, some can be good. Its possible they started high, and work their way down with cost cutting until consumers start to complain, possibly they were still getting good reviews. A video will be coming out soon with me complaining about typical modern ported subs if you're interested. Also, regarding the tube, it'd work as a quarter wave transmission line if you haven't heard of transmission line enclosures. Basically, they tune around: 340 / (length in metres* 4) So, for a 2 metre transmission line, it'd be 340/(2x4, or 8) which is ~42Hz.

[@djijspeakerguy4628]

@@Dakoustics I’m familiar with most of this. My favorite subwoofer is a 10 inch front firing driver with an extremely low resonance, heavy cone. It’s in a box that measures approx. 34.3x 34.3 x 38 cm on the outside. Approx. 3.8cm should be subtracted from each of these values due to wood thickness. Flared rear port measures around 7.5cm wide, 16.8cm long. It goes down to 28hz cleanly, but perhaps not super loudly. It’s great in a 3x3 meter room, but not much larger than that. Do all these measurements work out?

[@herrtrigger7220]

Anyone know if the woofer diameter matters? I have different online calculators saying one 4" port should be from 3.8" to over 100 inches to get 25hz in 8 cubic feet. They cannot all be correct. None ask about the driver itself. Is a 10" sub going to have the same response as an 18?

[@iisreallughtkingsun4360]

Thanks for this information brother. I truly know how This sound travel makes a big difference. Brace on the port. Again thank you ✌✌✌✌✊✊✊✊👍👍

[@vaportrapwave2658]

My method is to use 2 or even 4 ports, I think that this is a solution to mix pros of both methodes. It working very good. ;)

[@CoreMaster111]

I don't know if I'm wrong but when you used the vent diameter calculator you entered 60mm for Xmax which is insane because that means there is 60mm of excursion in either direction giving total of 120mm and mechanical limit would be absolutely insane. Xmax of 30mm would be much more logical.

[@Dakoustics]

yeah, derped on that one lmao, but I know of 3 subs capable of such a feat, Ground Zero GZPW 15Xmax, I've seen the MTX 22" Jackhammer do it from memory, and possibly custom Sundown Audio Team Neo 18".

[@keatonjones6115]

Thanks dude, this was incredibly informative, like most of your vids ofc!!

[@Synthematix]

Im building a 5.25" pc drive bay speaker out of styrene plastic and 2x 3w creative drivers out of a creative travelsound 400, im opting to rear port it and am going to make it rectangular as these seem to work best in my experience, the port will be exactly half the width of the enclosure. these little drivers sound absolutely beautiful with a PAM8403 5V class D amp, the amps are tiny and pack a punch, ideal for drive bays.

[@amykang472]

Long live the BOSS,finally I got what I need,god bless u

[@djijspeakerguy4628]

I like the sound of an overly long port. In fact, I mounted some tiny speaker cones at the end of some wrapping paper tubes, and it sorta sounded good! (A little echoed though.) the resonance frequency of the smaller one that I had was 58hz. I could not tell the bigger one though.

[@johnbacani2323]

I noticed this too in different port set ups that I heard

[@mohsinsheikh91]

Actually i didn't understand. Tell me if i want to make an enclosure of 1.5 cubic feet to tune it at 32 Hz. What will be the dimensions for both round ported box and slot ported box?

[@gucciflip-flopzcruz5467]

Medium ports have been good to me! “commented before I watched” thanks man I build probably 10 to 12 box’s a year an have always wondered but just used common since to keep it strong an quiet!

[@Dakoustics]

Perfectly reasonable, learning from experience is a great way to learn things you don't forget.

[@akuncrazy]

at 5:00 am I do not understand the comparison, and what is the meaning of the medium port?

[@The_secret_truth444]

I am trying to build my first subwoofer box on my own with the help of my father-in-law who is your carpenter and has the tools to do all the round do you know flares and 45s and everything else you need to get the air flowing properly I’m also looking in on how to build more complex boxes like fourth order six order stuff like that but you kept it simple which is what I need and give me information on where I can find the dimensions I need for my subwoofer thank you very much I subscribed and liked your video because it is awesome keep up the good work.

[@Dakoustics]

Cheers, good luck on your future projects!

[@The_secret_truth444]

@@Dakoustics thanks man. It’s an art in my eyes. Like geometry meets physics.

[@nomore4me286]

If the idea of a subwoofer is low bass..I would have to admit the lowest bass that I ever heard was without a doubt a sealed enclosure. I will never use a sloppy port system again but, then again I enjoy controllable, accurate bass.

[@brotharobmusic]

I had a seal enclosure that drop extremely low but as a former box builder, 4th other bandpass are the loudest and lowest sounding box there is

[@glennbeck9496]

@GudMusic4Lyfe The loudest and lowest is not the most accurate or best sounding though.

[@johnnycorn7225]

My man, preach, you can't go wrong with the same cubic feet of airspace when you double the surface, and double the power, and take the port away. It's worth the extra cost if you want maximum musicality. As a musician, I could never go back to a sloppy ported design, and yes I can hear the slop in those low tuned max spec airspace"sq" ported builds, every one of them. Ported ruins the impact and transitions of intricate drumming as well. Music needs to be right, and sealed can slam w enough power.

[@olekristianrannekleiv762]

Correct me if I'm wrong but I believe Large ports reduce compression and avoid changes in frequency response at different sound levels. The statement about large ports being boomy I believe is wrong, the enclosure size determines the sound signature of the subwoofer, the port size matters when it comes to remaining the sound signature at different sound levels.

[@Dakoustics]

If you meant large ports as in long ports, just read this. Smaller enclosures require longer ports in order to maintain the same tuning frequency, and the port covers a wider frequency range. I'm not sure about different outputs at high power depending on the frequency, as that would have something to do with power compression, and I'm not sure where the energy would be going other than mechanical stresses in the driver. If you meant large ports as in wide ports, read this. Large ports is a tad vague, larger than the ratio I mentioned, or a certain port size for a certain box size? Anyway, I've done testing, quite a bit too, different tunings, port areas, as well as watching others, (I'll also mention I forget all I say in this video and cbf rewatching it) but the general hypothesis is: if you have a larger moving mass of air, being a longer, wider port, it will store more mechanical energy whilst oscillating as a part of the resonance chamber, and this stored mechanical energy is dissipated by a decayed roll-off, which can extend tones further than the input signal, resulting in distortion. This large mass also has a rise time, so soaks up some of the initial input power before it resonates at peak amplitude, one of the reasons it's ideal for SPL. Smaller ports with a lower moving mass of air have this parasitic oscillation damped more quickly, and thus shouldn't soak up the beginning of its tuning frequency, and extend beyond the end of the tone, and in between produced an exaggerated tone as a peak. So, in essence, large port, efficient resonator, exaggerates its peak frequency and adds distortion; small port is more damped, inefficient resonator, should be more rounded.

[@olekristianrannekleiv762]

@@Dakoustics intresting answer, ill look deeper into it when i have time, you will hear from me.

[@olekristianrannekleiv762]

@@Dakoustics Latest reply ever! I forgot about this video but I have been thinking about what you said and I'm now convinced that there is indeed a benefit with smaller ports that I didn't see before, however, I have heard that a common port velocity goal is below 18m/s, what are your thoughts on this?

[@ViezeVingertjes]

I made a box container a subwoofer, all-range speakers and a pair of tweeters. I have 2 ports where air goes out/in, but the pressure from the subwoofer seems to push the all-range speakers out also. Not noticing any effect on the sound though, but would it be a massive problem those move along? If so, would just add another port to release pressure be the best option? Or would it sacrifice the bass?

[@Dakoustics]

Best option is to make chambers behind the speakers being pushed out. It can be hard to tell a difference in the sound, though if the speaker is pushed too far it could burn out. Adding another port will only change the frequency they are damaged at, not reduce it completely. Making a bigger box can help, though best way is to not use the shared air space.

[@Jeffdachefz]

Thats to get you in the ballpark. Actually ideal port area is based on xmax, power and tuning you want to model it out vs taking a blind guess based on general recommendations.

[@beerstein7137]

Good video. Also. If you go for say 3 smaller round ports instead of 2 larger round ports the 1st order port resonance goes up

[@anastasiasanchez7852]

But would it give you a longer bass hit

[@akolngto9314]

Sir just correct me if i am wrong. Example i have a total 2.75cu.ft of the box. Am i right? My port wide is 2.75” and lenght of 26”? Just correct me sir if i am wrong of my coputatuon for my width 2.75” width?

[@webflys]

What's important (and the original purpose) of a port was that it STARTS (at the back of the driver) the size of the driver, then increases in size (preferably radius) by at least 2x - by the time the channel exits (port opening). Should look like an ice cream cone : ) Listen to your small phone speakers THEN put a funnel right on the speaker and watch it get 3 times louder 👍

[@Dakoustics]

That would be a horn, which is similar to a ported speaker in essence, though is bigger, and harder to design, though is louder. Horns are like the ideal port.

[@webflys]

@@Dakoustics Almost... A horn is www.amazon.com/Klipsch-Palladium-38-F-ESP-Floorstanding-Speaker-Espresso/dp/B00M9YPM58/ref=sr_1_8?keywords=klipsch&qid=1571919788&sr=8-8 this speaker for example is rear ported. Here is the design I use kzbin.info/www/bejne/e3bLYWSGjZKkb6s

[@Turdpuncher]

Horns are for p a systems and other setups where size of an enclosure dont matter. Old record players were some of the first use this design. But it isnt by any means ideal for every audio system. Most stereos today are becoming more compact do to appeal and practicality as technology increases ,the watts per dollar becomes more and the end result is unideal ports or passive radiators being used along side longer throw speakers and alot more power at a low price. And this is only home audio im speaking of, car audio is almost the same, high xmax and gobs of power to overcome any size restraints.

[@cutrightsi]

How do you calculate your port length... im goning for spl and have read not to be any longer than 8- 10 inches ... problem is with my port area being right at 8-10 inches in winisd im getting my tuning higher than I would like?? Wanting a spl box with good bandwidth in a accord wagon

[@Dakoustics]

I've not heard of a limit for port length before, but you've got 2 options I'd recommend- If you're at or near Xmax, make the port longer. If you're not, make the enclosure volume slightly larger to get the desired tuning.

[@nicholashubbell5308]

Ok so now tell me will oversizing the port help the enclosure do better in the lows? or is that not really a question that can be answered to the length and diameter variables to follow the 16 rule?

[@Dakoustics]

Increasing area increases frequency, increasing length decreases frequency. If you double the area, to keep the same tuning you need to double the length and vice versa.

[@Zoki_and_Hes_Dogs]

You can make 3x 5-7cm small port's, if is a big port not possible to make or the sound are not that what you want. A little bit longer time to work, but the result Convincing. I'm testing it passive radiator with 3x 7.5cm ports and my reaction to the first sound was only a "WoW", it was not possible to make one big port, not enough space/distance from speaker magnet to the back side of the speaker box with the ports, in the middle not possible to make a port, but 3x small port's like triangle around the magnet.

[@agghell224]

Do we have to calculate the net volume or the volume of the box? to find the sq cm?

[@Dakoustics]

net volume, just the inside of the box, if the box is wide/flat and has thick material net and gross volumes could differ drastically

[@agghell224]

@@Dakoustics I didn't mean the outside dimensions.I was talking about the liters of the port and from the subwoofer. We have to remove them from the volume?

[@Dakoustics]

@@agghell224 subwoofer yes, port is 50/50 as technically the air inside it also compresses slightly, though I would say subtract the port volume from the box volume, better to tune too low rather than too high if it's off slightly

[@agghell224]

@@Dakoustics I m working subwoofer boxes with winisd but it s not clear the point of the volume. I always calculate the net volume of the box without the space of the port and sub, but i had to insure that from a specialist like you. Thank you for your time.

[@Boosted_Tractor]

So by the port ratio in the video I’d need 72 cubic inches of port area on a 4.5 cube box?

[@Dakoustics]

yes for rectangular/square port, can make it smaller, say 50-60 for flared round port

[@jdavibedoya]

Is there any difference between the resonance frequency of the port itself and the resonance frequency of the system (i.e., the box plus the port)? I have come across some texts that describe them as distinct frequencies. Thanks for your help!

[@panchoelliot7375]

Does the position of the speaker upright, slanted, or flat ,has an effect on the sound, especially the bass?

[@97warlock]

what about for a 2x15 Guitar cabinet??? it has 3" holes ...... 2 of them. Seems way to much air escaping, what do you think?

[@brutalbasspro]

Building a box for a customer following manufacture specs. 3.75 cubes 42” square of port space for a 15. Port seems big to me but we will see what happens.

[@tonyhunt9049]

What's the calculator link address (at 41secs) please?? I had this, but lost due to computer failure. Thanks.

[@jamegumb7298]

So say I'd want 5-8cm wide flared ports on a Celestion TF0818. What length is ideal? If I were to use dual ports, would I be correct in thinking 2 ports of 23mm or 1×30mm? Sounds wrong.

[@akuma4u]

I was told smaller ports hit wider bandwidth and have way better roll off. For example i got a 2000rms sub 35mm xmax. I was told to do 2 cubes and use 24 sq inches of port.. rectangular slot port. Would u say this is too small??

[@Dakoustics]

24"sq is fine, the only real big differences in audio happen when things double or halve, since this is 75% of what I suggest, its in the ball park, if it was 10"sq chuffing, compression might start to become more noticeable. Also depends on your tuning, lower frequencies tend to be more forgiving for smaller port surface areas. Heck, I run 4"sq per cu ft in my 17Hz tuned 6th, though its nicely flared so chuffing is never an issue.

[@akuma4u]

@@Dakoustics im gonna do a 1.75net 36hz box with 21 sq inches of flared slot port on a 2000rms sub with 30mm of xmax. Do u think this will be ok? I was told using the smaller port area will have better rolloff above and below tuning frequency and give a wider bandwidth

[@Dakoustics]

@@akuma4u It should be fine, funny thing about better roll-off below would be due to choking the port which sounds like chuffing galore, in fact I've tested boxes and under port tuning long, wide ports act like transmission lines, which have an 18dB/octave roll-off, rather than typical 24dB/octave roll-off.

[@akuma4u]

@@Dakoustics ah..well. I hope i dont hear the chuffing...this is a test box i got someone to build for me for 100 bucks..if it fails im going back to a big port like 18 to 20 sq inches a cube.. When i researched port area i found there are 3 beliefs. The 1st group told me to put as big of a port as possible to decrease velocity so at higher volume i get the most output. Im talking about 25 to 28 sq inches a cube. The 2nd group will say stick to traditional 12 to 16 a cube. The 3rd will say 10 to 12 a cube for best sq, widest bandwidth, brutal velocity and windy pressure and excellent roll off..

[@johnemanuel5593]

Please answer... I have 12 inch sub for home theatre... The box is 15*13*24 inches with sqaure port of 2.25*20.25*12.05 inches Is the port is good or not.?

[@Dakoustics]

Yep, port should be fine, although I'm basing that off the port being 20.25*2.25 inches area, and 12.05 inches depth.

[@johnemanuel5593]

@@Dakoustics yes.. Thank you sir for your reply

[@akolngto9314]

Degital design chart for the port? Is that for sound qaulity bass or spl bass?

[@abhishekdave5306]

Can i use 4ohm 30w subwoofer instead of 3ohm 10w woofer (stock) in speaker?

[@brotharobmusic]

Im old fashion, i never built a slot port. I have always use PVC pipes for my ports. The longer the port, the lower the sub will play. For 12" subs I use 3"-4" Diameter ports, for 15" subs I use 4" diameter ports and for 18" subs I use 6" diameter ports..... my ports never whistle or build up turbulence I like the video btw

[@brotharobmusic]

Best to flare them no matter what diameter size

[@Rentta]

My rule of thumb is 4" for 12", 6" for 15" and 8" for 18". All flared obviously

[@mitchellroberts7954]

diameter or radius? a 4 inch port for a 15, and 6 inch port for an 18, is absolutely ridiculous. I would never go smaller than a 6 inch port for a 15 and 8 inch port for an 18. Either you're using very low power, or drivers with low xmax, because you will get noise with a port that small on high xmax drivers on high power.

[@brotharobmusic]

@@mitchellroberts7954 you dont get wind turbulence using the sizes i explained. As mentioned, we flared them all. I hit a 153db using a single 15" DD 715 using 1300 rms with a 4" dia pvc port. No whistle of anykind. Of course all the sizes i mentioned are the minimum recommendation. Too big the sub wont pressurize like it suppose too and too little the port will whistle. Even with a small port, when the enclosure is in your trunk you hardly can tell its whistling. I have heard many systems when they pop the trunk its whistling but in the listening compartment it sound good and you can't really tell... of course if you're using a 4000 rms sub i recommend 2" bigger but for the average joe, those measurements are on point!!! every 15 or 18 doesn't need a really big port. I speak for myself but i never own a 3000rms&up subwoofer. I hope to change that and experiment

[@kennethblindheim2676]

@@brotharobmusic 153db from a 715 probably wasnt tuned very low, 4" is fine for a 40hz tune. But its too small for a 30hz tune..

[@abdelkaderelbachir3059]

Just like aiwa from the 90's and early 2000's

[@jonrengallana7764]

Yeah.. The NSX-999 mkii have two ports in one box the smaller one the bigger one which have same length and sound good about 24 yrs. and still working, listening to it.. -QUALITY SPEAKERS... AIWA

[@shyamsachin5578]

Nsx s 94...same ports

[@masaminhobimancing8938]

if i have an 18 "speaker ... how to determine the box volume and port on the speaker box ... according to the data on the speaker ... thanks

[@Zack-dk3pt]

i made a box completely ignoring the consequences of turbulence. tuned to 24hz with a small diameter 2ft long port that made a massive amount of turbulent noise. luckily for me it was in a sealed trunk and i never heard the noise allowing me to achieve stronger dampening at a low tuned frequency. i meant to tune lower but whatever i did ended up producing stronger resonance at 24hz which i was happy with nayway.

[@HarmonicResearch]

Any port makes the bass boomy. A much better design is acoustic suspension (sealed box). You can get just as low a frequency response by increasing the box size. This gives you "tighter" bass that is better controlled and not boomy. If you want a small box AND low bass, you can add a tube instead of a port. Use vacuum tubing in place of a port. Make it long enough to resonate at the low frequency you need to reinforce and fill it with fiber to dampen the resonance and seal the end. I did this to a cheap car speaker in a tube and was blown away by the tight, deep bass that resulted. The tube was about 3 feet long. A 4 foot long tube would give you lower frequency reinforcement. Several tubes could be added to taylor the system as you like.

[@seanlevifreerider9956]

What would be the best for sq?

[@iakopklein8218]

So let me know what is good small port or big port

[@OK-st9st]

I’m not the best with math, but I have 2 18” subs in a 40”x42”x33” box. And 4 4” circle ports 4” deep. Feels about 65hz but idk. How would I make it lower?

[@Dakoustics]

Appears youtube yoinked my 500 word comment so here's it abridged: check amp doesnt have subsonic, check signal has bass in it, ports coould be bigger and longer, program says it's already tuned low so wider+longer ports keep same tune but make it more efficient, and be sure your subs are good for lows, as in some PA woofers although 18"s might be just for midbass, might be worth a video on the topic

[@doublemanson]

🔴Does 16 sq inches per cubic foot also apply to aero ports, if not is there another number.

[@christhopherlasher2828]

Question this is great for sound quality and I'm not into SPL but I do you like to move hair. Can having certain size ports increase my chances of having a standing frequency in the vehicle for hair tricks? I know this might be a little vague of a question but any input would be welcomed. I would like to do it with ported boxes because I don't have spacing to do anything but I one-to-one fourth order inside of my cab

[@Dakoustics]

Bigger the car, the harder it'll be to achieve a hair trick. The main thing is moving as much air at as low frequency as possible, or at least below the tuning of the car. Cars with open windows act more like 4th orders themselves, so playing slightly below the resonance of the car is the best way to move air through a window. Standing waves are more important for SPL. Something I'd suggest, is make a ported box as big as possible. Put 2 ports into it, where it's tuned to something like 30Hz for musicality, and when you want wind plug one of the ports to tune it closer to 20Hz.

[@wyattjefferies3449]

If you email the manufacturer, they will tell you exactly what size box and port to use to get the best sound for the size speaker and amplifier you are using.... Kinda takes the guess work out of it, just saying

[@tomkocur]

Just as it was mentioned in one of the comments below, manufacturer recommendations very often lead to unnecessarily high tuning. There is no single box and port size that works the best for every kind of situation.

[@drrckhamilton]

Does this apply to 4th order bandpass boxes for cars?

[@castielhamidi8327]

hey man, love your info. I have two of bowers & wilkins ccm382, i like to make my own speakers for each side of my TV, how can i calculate how big the speaker box should be?

[@chadfowler1443]

Is this the same for normal speakers (not subwoofers)? I am building a custom bluetooth speaker and am trying to calculate the correct port length. My driver is 4" diameter, with a enclosure volume of 0.21 ft cubed and a resonant frequency of 81.4 hz

[@Dakoustics]

yeah, it should work for any tuning frequency

[@chadfowler1443]

Dakoustics awesome thanks

[@hydrolink5297]

This really helped. Thanks man!

[@chipburns4123]

For a ported box or 4th order bass reflex box 16 cubic inches is great but that number is different for other boxes like a 4th order bandpass box where you would want more like 20 sq inches of cone area.

[@dclarke2814]

if you're increasing the area of the port.. doesn't this also affect the length as well... if so what ratio?

[@Dakoustics]

surface area to length ratio should remain the same, so if you increase surface area by 25%, make the port 25% longer.

[@justinkcraig]

My subs only have (15" planet audio)13mm and (10" power acoustik) 15mm of excursion. That huge port may have been recommended because of your giant excursion # ? Though I'm mindful of subs specs I lean towards the larger port size, My rough general rule For 10s and 12s I use 4" and for 15s I use 6" ports or close combo equivalent. When building slot ported boxes I keep the general size rule in design but can be bigger or smaller depending on the so many factors . Also I prefer my built auto sub enclosures tuned around 31hz to 34hz , so my ports are a big factor . I'm currently pondering a single 15" with 2×6" ports that will be like 30+ inches long each that will be mostly external and a part of the exterior design for minimal box size(still 3+cu.ft.net.) and a unique look without skimping (I'm bored with plain old gray/black undersized generic prefabs). Let the subs breath DEEP! I'm "BRAINS over brand " in Tacoma Wa .

[@furmantucker4989]

Is the box area example before or after adding the port?

[@reeves1001]

Soooo. Ummm. What if my box doesn’t have a port?

[@tss91994]

A large or small port depends on Thiele-Small parameters of the speaker and what frequency Yuit want the box tuned to. Flared ports are always helpful.

[@SoXDYTB]

Hello , port square inches should be calculated per net internal volume or total internal volume

[@michaelangel6201]

Speakers boxes should be designed around your speaker's perimeters, and not the opposite, this information is usually found on its data sheet as Vas, FreqHz, db and EFF. There are plenty of programs where you can just plug this info in and it will give you the exact size for the FreqHz that you desire...With speakers there's no such thing as "One Size Fits All" even with the same spec' s but different manufacturers. I would recommend Thele-Smalls formula to start with an adjustable port tube and a remote controllable baffle. This is what we did back in day while living in Calli and we would blow boxes, windows and the competition apart...Literally.

[@Dakoustics]

Working on a Thiele Small vid right now, should be up in a few days.

[@michaelangel6201]

@@Dakoustics It appears, you're a person whose on top of things like a "duck on a Junebug" so I won't bore you with the minors that so many designers get wrong with either building or designing custom enclosures. Just remember sub's are more in the realm of being resonant "Air-pumps" than acoustic devices. Thanks for replying, Mike

[@Turdpuncher]

​@@michaelangel6201 why would you think they are more like air pumps? Sure 30 and below tends to get windy, but not everyone wants a fart machine. Spl realm is a totally different world . Chasing numbers is an extreme extension of audio, and while it lends some r&d to the design of modern subwoofers, it doesnt cover all the aspects of a good audio system. Your words on the use of parameters to design and tuning of ported enclosures is spot on and i agree 💯 .

[@HIGHROLLAZAUTOCLUB]

The info you got there from DD about cubic feet and port calculations. Is that before sub and port displacement or after?

[@chrisa9035]

Best advice you could give the people

[@95Sn95]

I've been doing alot of wondering about my port size I built my box with a tuned to 35/36 with 129.5ci port area (7"x18.5") for 2 American Bass XR15s on a 2k amp, the box is around 6.75cf and on the low low bass it sounds killer smooth,clean and hard hitting but the long test tone higher frequency notes I get a ton of nastyy muddy boominess that is unpleasant and uncontrolled sounding, I plugged the port and it sounded Awsome but I lost about half my output... unacceptable. I also screwed up when building my box I put the port in the center vs off to one side like the plans and took the 12" rear leg and made two 6" opposing legs but forgot to make the width half so each side leg has the same port area as main center port making my tuning 35/36 vs 29. Any input would be appreciated...

[@armandobaezpintor2776]

high, have a 18 inchs speaker of 600 RMS 1200 watts , what box is good for this bass? I¨m from México city, thanks.

[@Dakoustics]

my guess is ~150L/5 cu ft, maybe even bigger, but i can't say much more without knowing the specs, most likely 32Hz tuning would do well, purely going off a typical 18" 600w sub

[@armandobaezpintor2776]

@@Dakoustics thanks, many

[@wuensonchan48]

@@Dakoustics the speaker is the TR 18B-1200, SPL 99 , the speaker is from Canada.

[@montanaplease]

I don't care what spec the enclosure is there is "ALWAYS" going to be a compromise with it.... every single time

[@RobHTech]

Agreed. succinct. done

[@Chris_Wolfgram]

Of course round ports are more efficient, and require less sq in per cu ft. I already knew this. But you didn't say "how much smaller", so I'm still trying to figure out how many sq inches I need with my round ports in a 2.7 cu ft box ?

[@Dakoustics]

a single 6" dia port should do you well, but generally you can get away with 12" sq round aeroport per cu ft

[@kishoresolanki3576]

So, summary is big port better than small. Like 👍the video

[@jhsevs]

Have you ever done a video on port length, port shape and port placement/location?

[@nj5374]

From what I understand, port placement is not relevant due to the extreme wavelengths that travel through the port. +1 for info regarding port length tho

[@fredbradshaw3835]

I do know that ur supposed to keep ports 3-4" from any exterior walls, thats including when the port extends into the enclosure at the point the air is leaving the port. I believe also stay away 4-5" from any interior walls. Kinda rule of thumb. Port placement is kinda important. Enclosure size and quality and ur port is what makes a good sounding enclosure. Just sayin.

[@TaylaFam]

How would I find my ports displacement?

[@sMASHsound]

what is the best port lenght?

[@MickyMouseLimited]

I there is something wrong in your video on 0:27 sec. 60 mm XMax is huge number that I don't think is very popular as you describe it . This means the woofer membrane is going to be able to move over 2 inches out and 2 inches in . Can you please give an example with a speaker with this abilities that is really popular.

[@nighttow8780]

Doesn't total surface area of the diaphragm combined with x max have anything to do with port area? One website I went to said I should go with a short two and a half inch port, well another website suggests that I use a very long 6-in port. But both suggest that these ports will result in 34 Hertz tuning. How can that be? Doesn't Port area also affect tuning along with diameter and length? I have everything I need to put this sub together. But I am absolutely befuzzled by Port area. Trying to do a 1.25 Cube box tuned at 34 HZ for a single low budget 10-in sub, to be installed in a single cab pickup truck. Port area dramatically affects the external dimensions of the box. And my space is tight.

[@thedubwhisperer2157]

Rules of thumb: Start with port area equal to Sd and work backwards until it fits in the box. Port length should not exceed twice its diameter. Port should be circular with appropriate flares at both ends. Port termination should be similar at both ends to reduce port rectification. Enclosure and port size are closely interrelated and change dramatically with desired F3 and the driver TS parameters. Don't expect high efficiency at low frequencies from a small enclosure.

[@celsonudo7209]

Is it possible to devide the area of the port.

[@dont.ripfuller6587]

My girlfriend has a box with a large port and she's always saying the length does matter , can I just tell her if the port was smaller then the length wouldn't be that important because it would travel the full distance quicker and would seem like there was more there coming out then there really was eliminating the need for all this and that extra length and size and stuff well her response was to go to the neighbors and see how much sound they can get him pushing in and out of it

[@ashikreji5869]

So which is better bass

[@CharlesDowiot-qv7pp]

If you have a High power speaker usually have large Bass port lower the power less the bass port