What's the difference between a front ported loudspeaker and a rear ported speaker? And check out our newest CZcams channel / @octaverecordsanddsdst... Octave Records.
Most port designs take advantage of what is called "helmholtz resonance", much like what produces the sound in a pipe organ. By tuning the port/box/woofer combination, one can use this phenomena to produce bass notes at lower frequency and higher spl than the woofer could in a sealed box at the cost of (usually) a larger box. At least that's how I understand it.
Can we say that a studio monitors with ports gives us different bass frequencies than are actually recorded?... so treating the room or blocking the port does similar things... I use the monitors very quietly because of neighbours, so will blocking the ports take my room out of the equation?... thank you :)
G.day brother what would u recommend in my case.I want to build a low mids box for my car audio use if 6 12” should I build a ported or seal box plz note that the boxes will be facing outwards back the back door window
Every programming language has bit-shift operators. Although it's generally true that you can only take advantage of the carry bit and use circular shifts in machine language - unless the compiler is intelligent and can understand that sequences like this can be implemented with a circular-shift instruction: #define MSB_MASK 0x80000000; int Cbit, shiftreg; Cbit = shiftreg & MSB_MASK; shiftreg
Glad to see you're promoting the elac line I have a set of UF5 Towers and the UB5 bookshelves and hoping in the near future to purchase your Sprout 2 for my UB5's great job🎧🎶
I've recently been doing plenty of experimentation with ported box designs, including making my own 6th order bandpass box, and here is what I've learned about how ports behave. They are in fact in phase with the diaphragm, due to their resonance their phase is inverted, causing them to add to the air displaced. If they subtracted, there should be an output dip either side. This also causes an impedance dip, as the pressure within the box, experiences a peak caused by the added displacement. The driver moves slightly less due to the pressure, and causes an impedance dip as EMF decreases voltage being fed back to the amplifier. Efficiency is increased as power is "shifted" from moving a diaphragm with relatively high mass to a tube of air resonating, with a relatively low moving mass. Ported boxes have a steeper roll-off than sealed, as the port doesn't allow pressure to build up lower than its resonance. Low frequency air flow may come and go as it likes. It behaves sealed at higher frequencies, however only reflected waves come through. Due to bass having an inherent non-directionality associated with its creation, the speaker box is simply adding or subtracting the local air pressure around it. Phase from front to back shouldn't matter. Enclosures where it does are referred to as "dipoles". Port surface area is relative to length for tuning, possibly why front ported boxes have longer ports is due to a greater surface area attempting to eliminate "chuffing" with lower velocity airflow. As far as I'm aware passive radiators behave like ports, though without chuffing, are less efficient, and from what I can tell work better with smaller boxes than ports. Transmission line speaker enclosures work by having a set transmission line length, usually tuned to either 1/4 or 1/2 wavelength of the desired tuning frequency, feed the rear wave down a tube with said resonance. Port width is usually equal to the driver surface area and constant along the line, unless a tapering/horn loaded design is used. The effect on the air from thought experiments is like hanging a weight from a bungee cord, move your hand at the resonance of the weight, and although your hand is moving only a 1/4", the weight may be moving 1" or more. This works similarly to a ported box, though requires much more space. Generally transmission line boxes reach the lowest notes, though this may be due to them performing as dipole enclosures down low. Dipole enclosures (also from thought experiments) effectively add a springy moving mass to the driver, lowering its resonance, which improves low end. The distance between the front of the driver and the rear creates the pressure differential, and therefore sound. I kinda fell half asleep whilst writing this, so hopefully it makes sense
"They are in fact in phase with the diaphragm, due to their resonance their phase is inverted, causing them to add to the air displaced." This is not true. At the precise resonant frequency, resonators respond IN PHASE to the driving function. Thus port emissions exactly at their resonant frequency will tend to cancel the woofer front wave and produce a narrow dip (notch) in the response. Resonant systems exhibit a large shift in phase response, comparing at frequencies just below and just above resonance. Ultimately, an undamped system can exhibit nearly +/- 90 deg. phase shifts across a narrow frequency range. In the region below resonance, the port can add boost to the woofer, but at or above resonance it tends to partly cancel the woofer front wave. If you do careful response measurements at small frequency steps for a ported speaker system, you may find significantly uneven results.
He seems really nice.. and it's rare to be that humble and open as an executive (which I think he probably is) Great video and I learned a few more things. I see why closed subs has an advantage being active.
Very nice explanation.I learned many things.There are also down ported speakers like Wharfedale diamond 200 series and diamond 11 series (no chuffing noise at all)!!
The pressure inside a ported box is actually higher than a sealed. Low frequency waves actually go through the box a whole lot easier (below the tuning frequency of the enclosure, Fb.), this is called unloading. Below Fb the speaker increasingly "sees" no enclosure at all and will rolloff at ~24dB/octave. To avoid damage to a vented box with somewhat high Fb you need to highpass the frequencies below Fb as these will cause excessive excursion to the driver. Port "chuffing" can be largely avoided by simply decrease its air velocity to below 17m/s. Many use flanged ends to help alleviate this problem as well. A well designed port/enclosure will won't have these issues to any audible degree. A T/L and vented enclosure is not the same thing. Front port or rear ports really does not matter at all in a technical perspective. The wavelengths at low frequencies are so long that the port placement only amounts to a fraction of a frequency cycle's phase difference. You must have some distance (normally at least the vents diameter) between the wall and the backside of the enclosure which can lead to issues if you try to hang it on a wall or something. The main reason they place the vent at the back is to be able to save space really. Futhermore, a vented enclosure is by itself more efficient and has lower non-linear distortion than a sealed enclosure due to less excursion around Fb. This of course increases the maximum output of the driver within its voice coil thermal ratings. The only thing that a sealed enclosure is better at: as mentioned, the actual group delay/phase shift. The vent cause a phase shift in its passband which increases its group delay in these frequencies. This group delay's audibility must be seen in relation to the actual frequency. At 50Hz a full period is 20ms (1/50=.02s), while at 25Hz a full period is 40ms (1/25=.04s). With certain alignments the group delay can exceed a full period, at some point it starts to get noticable and this is what people refer to as "sloppy bass". A lot of times this issue is fixed by simply equalizing the frequency response as group delay is a derived function of the magnitude and phase response. The enclosure-inherited group delay of a vented design can be fully corrected for with FIR-based signal processing. In my opinion, the vented enclosure is usually far superior to a sealed box, especially if you got a powerful DSP / room correction. Note that not all drivers are suitable to use in vented enclosures, most high Q-drivers should be avoided for example.
I recently purchased Kali Audio front ported Studio Monitors. I used to have the Yamaha HS8's, but the 8" woofer with the rear port produced to much boomy bass as my studio is small thus my speakers are forced to be closer to the wall. The front ported Kali Audio monitors with 6.5in woofers and front port design fixed my issues perfectly. In addition they have a trim pot to compensate for speaker locations and room environments. So sometimes front is better depending on the the acoustics of your listening room.
ooh, fancy little Elac speaker, Jawhol ! I have passive radiators in the front of my 1978 Philips AH-487 speakers. It looks like a woofer membrane without the magnet and the voicecoil etc
I wish you’d do a comparison of sealed , ported , and passive radiators. I’m personally a fan of how passive radiators sound. But there’s very little information available on them
Paul, your description of how a port works is much less pornographic than Zeos Pantera's attempts to explain why that hole is there and I thank you for that. There are books dealing with loudspeaker design and I'm sure my 'accountant' will let me buy one when the time is right (hell freezing over, apparently) but until then I'll have to rely on the insights of people who actually do this stuff for a living. I look forward to the new PS Audio speaker even if I know that it will be many multiples of that Elac bookshelf you held up at the start of the vid - thanks again for the video.
Whenever you have to deal with an accountant that tells you "when hell freezes over", remember that there is a town in Norway called Hell. It's not far from Trondheim. So "when hell freezes over" is probably somewhere in late october, early november.
I actually have had 2 different surround speakers series by Psb Audio with ports and found the number of ports made a difference as well. My current speakers have 3 ports and I also have port plugs.
Every port shifts the phase by 90 degrees at its tuning frequency, no matter on which side of the enclosure it sits. If it's on the back you usually lose a few decibels in the bass because the phase shift increases due to the time it takes the sound to travel from the back to the front. Wave lengths in bass are big in comparison to the dimension of the enclosure therefore they bend around the edges (spherical radiation). But ports also let a small amount of mids pass through which is perceived as distortion. In the mids the sound waves are smaller and don't bend around the edges. Therefore they don't reach the listerner if the port of a mid-woofer is on the back. With a port on the front this distortion might lessen the sound quality. The solution: port on sides, top or bottom as near to the front as possible. The huffing and puffing noises are generated by turbulences of the air flow inside the port and on its edges. Therefore those Elac speakers have a port with round edges. If the diameter of the port is too small the air flow gets too fast and turbulences occur even on the surface of the inner wall of the tube. The cross section of the port should be at least one fifth of the effective piston area of the driver. Even better is one fourth or more but the length then might become too big for the same tuning frequency. The standing wave inside the tube becomes a problem then. Before I discovered your "Ask Paul" series I started a similar podcast in German, apart from most of my other videos being in English. Im currently translating my first few episodes into English but it takes a lot of time because they were not scripted. On many of them CZcams's automatic subtitle function didn't even work. (The German version seems to be not that good yet.) If I gathered some more subscribers from the English speaking world it would maybe motivate me to speed up my work. Source of all my knowledge: German DIY loudspeaker magazine Hobby HiFi.
When properly designed and manufactured, ported speakers can be used in two different ways: if you have the room to have your speakers out from the rear wall, as in on stands, rear ported speakers will be your best bet. If you don't have the room, and may even have to wall mount then a front ported design would be your best bet.
I have a pair of B&W 804 D3 floor standing speakers. They sit 3 feet from the back wall but are close to the side walls. I didn’t like the mid bass boom I was getting so I have now put the supplied foam bungs in the ports that are on the front of the speakers. They sound way better now. If I add a sub (or two) to extend the bass down, would I still get any bass bloat in the room, seeing as the 804s are now “sealed”? Thanks.
These feel like hanging out with your grandpa on a weekend and he's teaching you about something your parents didn't want to learn but you're super interested in
My grandfather taught me how to break the windshield on a car with a jack handle. then flip his lawyers business card at the shocked driver. He hated car horns.
Very interesting subject. Vented speakers have (as you know) been around a long time. 1960's vented systems did tend to sound "unnatural". A.N. Thiele and R.H. Small research into vented designs was used by, I think, two companies in the early 1970's. Electro Voice and Ohm Acoustics. Venting took three major types; ducted ports, passive radiators (drone cones) and transmission line (labyrinth). I auditioned and purchased Ohm model L vented systems in 1978. I still enjoy these speakers today. Old argument was... acoustic suspension speakers sounded "tighter" than vented systems. My Ohm H speakers have an 8" woofer with a 12" passive radiator and bass is tight, deep and very satisfactory. I guess the main advantage of venting speakers is to provide deeper bass in a smaller box. Perfect for teeny weeny NYC apartments.
I have audiology Grason Stadler 162 with altec 418b loudspeakers. There is a lot of clarity with highs and no mid and low range. I was wondering if I should port the sealed enclosure.
I prefer the curve of my ported subs. High at 30hz and steep roll off from 40 to 80 hz. I've spent my life chasing after perfection and to me this is as close as I can get. They lack the punch of a flatter curve, but I'll take that trade off. There is only one song I know of where my setup has an obvious lag between notes and it bothers me but I would still not trade it for anything else, especially not a sealed subwoofer. So much of this has to do with what music you listen to, and I think when people have disagreements they sometimes fail to take that into account.
I can appreciate the use-case scenario. I personally prefer using a bigger amp and more EQing to get a similar curve from a sealed enclosure. I’m sure they’re out there, but I’ve never heard a ported enclosure with good subsonic extension. Ports can create phase issues that can be very difficult to address. Of course, if power limits at a large venue are limiting, a ported enclosure would make sense.
as an electrician i think of ported speakers as LC oscillator , the port is the inductor and the box the capacitor. you may also think of a spring (box) with a weight (port) attached to it.
Ports are a way to alter the physics needed of enclosure size to produce sufficient bass. I used to own a few of the Dunlavy speakers that were all sealed boxes - no ports at all. And they had terrific bass, but they were large enclosures (not very high on the wife-acceptance scale). If you didn't mind your speakers almost as large as your refrigerator, the bass was articulate, fast, and very real, with none of the problems with ports. Still the best I've ever owned.
Would like to say love your videos I have a question that is off Q but just curious your opinion I have mainly vintage Sansui equipment my speakers are SPX 9700 and SPX 9000 do you feel bet they have the quality of today's speakers
Because you used the word "vintage:" about 45 years ago, in the early '70s, I went to the Far East courtesy of the US Navy. In Hong Kong I purchased a pair of Wharfedale. I listened to everything I could, and back then, all of the Japanese speakers were really bad. Just terrible. Their electronics were much better. Hopefully Japanese speakers are better, now. I prefer American speakers. I suggest that you simply: trust your ears! Take some, a few, of your favorite albums and Compact Disks to a good hi fi location such as Magnolia, and Hi Fi salons, if you can, and compare the sounds from the various pieces of equipment. Try to purchase the best, most pleasing sound TO YOU, that you can afford. And, keep an open mind! It's possible that your current speakers remain satisfactory and pleasing TO YOU!
Do they still make Acoustic suspension speakers where the air in the box is used as the restoring "spring"? I have some old AR speakers that used this design and while they are less efficient than other designs, they very good bass response.
What most people seem to forget is that sealed speakers also have a port. That is the driver itself. The driver's backwave will resonate and reflect back through the cone in a number of rather unpredictable ways. And that is with all the stuffing in the world too. Of course if you set a whole room aside for the speaker we are close to infinite baffle and the effect will be very small. But that is fantasy land for most speakers.
Rear ports are more picky in regards to room placement. If a rear ported speaker is placed too close to a wall, there can be either an increase in bass amplitude or a cancellation of lower frequencies due to reflections and phase alterations of the sound leaving the port. Make more room behind them, and they will have smoother bass characteristics. Front ported speakers do not experience this problem, so they can be placed closer to walls. But because the port is facing the listening space, it might be easier to hear the port noise. I've got some rear ported bookshelf speakers, and they're pretty close to a wall, so I ended up plugging their ports. Their bass sounds muuch less boomy. And the reduced bass range is being taken up by my subwoofer. It's a win-win.
Sealed has a cleaner sound but requires more power. I personally think it depends on what kind of music you listen to. I dont know. I like a sealed box for rock and metal. But if you get into the hip hop style the speaker cant react fast enough and starts to bog. If that makes any sense. Love all your videos Paul.
NTH Welding , I had an old vintage pair of Advent 3 way speakers with a 12 inch woofer, 4 inch mid and 1 1/2 inch dome tweeter, sealed. I compared them to a set of equal speakers made by Cerwin Vega, no comparison, the Vegas blew them away. but on the other hand, the Advents although took more power to run as loud had a much tighter hitting bass frequency, so I just used all four speakers in the same room. the sound was great!!!!! it really comes down to if you have tube amps or digital amps and what type of music you like.
Firstly, thank you so much for these videos. I've only just dicovered them. Now I am.going to ask a very basic and possibly, naive question. What is possibly better between a scoop bin and a rear mounted speaker. 'W Bin'??? I've owned scoop bins before, but never a rear mounted speaker. Is one better suited to a certain situation? Size of room etc.
The port has an air mass that is suspended with the airvolume inside the box. When this mass reach resonance due to the triggered soundpressure from the woofer, it starts to resonate. At resonance, the air in the port goes out when the woofer does. This will enhance the bass level. The wavelength at 50Hz is about 7 meters, so it does not matter if the port is in front or on the rear. However, at lower frequencies than the ports resonance frequency, the air in the port starts gradually to get sucked in while the woofer goes out.
Conversely to having a port. Does the sealed speaker with the compression and vacuum going with the cone operation, vacuum when out, pressure when in, actually create a quicker stop and then quicker restore of the cone and reduce vibrations as the cone goes back to its central position. Thus making the base truer to the original as it is now self controlled. Overthrow and sluggish return are now self regulated by the size of the box in relation to the cone movement.
Hi Paul, a typical tuning frequency for a port will be something like 20-40 Hz. What's the wavelength there? How does that compare to the front to back box dimension? Thanks!
Thanks for the answer! But high end my speakers are not. 15" Pyle drivers, Horn tweeters, unmarked mid range in a plywood box with a massive rear bass port. They're designed to be efficient, at 10 watts they are deafening. But, anything I can do to improve the quality that they're reproducing I will do, especially if it's as easy as measuring and cutting the existing speaker cables.
In theory, different lengths cause phase shift between left and right. Reallity is that the amount of phase shift is so small as to be undetectable. Lets do the math. Lets say your left vs right lengths differ by 5 meters. In copper, electricity travels at about 280,000,000 meters/second. The time difference of a frequency starting at the left vs the right (Time Difference Td) = 280,000,000/5 = .000000017 seconds. At a frequency of 1000 Hz the period (P) of the cycle is 1/1000 = .001. Phase Shift (Ps) = 360 * Td/P Ps=360* .000000017/.001 = .00612 degrees This Phase shift represented as a percentage would be .00612/360*100 = .0017% I highly doubt that this is detectable. If this were aubible, we would have to listen to music in precisely the center of the two speakers and have only one ear placed directly precisely in the middle. The distance between our ears would cause much greater phase shift than the 5 meter wire difference.
I prefer sealed over ported, but some ported models are great also. Rear ported designs are much better than front ports, to me anyway. Sealed just has a cleaner smoother bass and just plain sounds better I think.
Ive got a question for Paul McGowan and viewers out there. I'm building a 2x12" speaker cabinet for a 100w peavey valveking head and wondered should I port the cab? I don't really want too as it will be a closed back cab, but does and will it make a huge difference in the sound if I do? And if I put a small hole in the cab say 10-15 or 20mm for example just to let the speakers breath/move properly within the cab and not let out alot of noise will this help with speaker over all speaker perfomance and or sound? Thanks and love your videos.
Actually the port sound output is in phase in its adjusted frequency. Due to resonance of the enclosure and the "Piston mass" inside the tube. Lets say you want to adjust the bass reflex supporting frequency to 35 Hz. You got a 50 L Box, than you need a round port approx 4" width times 12" length. Big floor standing speaker. Out of the adjusted frequency the "Air Piston" in the tube can not move properly, or even not at all. The fuction of the port increased if approaching the frequ. and its decreasing if leaving. But in this case it doesnt matter in my eyes, if the port is in the front or in the back. Because the wave length at 35 Hz is 10 yarts and you got a 1' deep Speaker maybe (front to back). So the back port would be 1/30th out of phase reaching your ears. Bass is emitting nearly 360° the same around the speaker. so doesnt batter to me. A passive Butterworth Frequency cross over for example, with -6 db per octave, generates a 90° delay in Phase in the low pass way, thats nearly 4' - Bass/Mid separation at 300 Hz . However it is the commonest frequency cross over. That tears apart the exact imaging of the stage arround the crossing frequencies. Some very smart invetors and developers build speakers that wave no delay in Phase, absolutely time coherent. A giant step towards natural sound play back. cheers.
Jean Katana Above the the tuned frequency the air mass within the port cannot move freely, but below it, it can. This is one of the caveats of ported loudspeakers, below the tuning frequency, of the port, the cabinet and port offer no control over the motion of the cone. The driver unloads, excursion shoots up with falling frequency, and the output rapidly reduces.
thank you for this video, sir very informative and constructive. plus the helpful comments. an exceptionnel 'channel' free of blah. blah. if you allow.....
G.day I’m all the way from Guyana I need to know if I should use a Ported or seal box for my low mids,plz note that the boxes are facing out the car by the back side window
From personal experience... I listen nearfield with the speakers at ear level. When I had front ported speakers? When certain notes were hit, it was like sitting in front of a hair dryer set to cool. On cold nights I would get cold air blown in my face. So... rear ports have another good purpose. I prefer sealed or passive radiator speakers. More accurate sounding.
Med always comes out of ports too (but at a really low level). But it's enough to effect the med tone and make the voice sound wrong. But if the vent is at the rear of the speaker the med (from the port) is less heard. That's why I reckon most ports are rear.
Interesting subject guys... What are your thoughts on a down firing ports on stand mounted, floor standers... Any strengths in that idea? Or is that a no go area? If yes, why? I know most rear ported speakers are straight through into the speaker cabbinette, so what about a series of baffles? Would that help or just hinder air escapement? I have been wanting to design my own speakers for some time, this is why I'm asking the question... One other thought, is what about some form of diaphragm mounted within the port, thus pushing the speaker cone forward when its on it's forward travel... So, in effect, the diaphragm is charged on the backward direction of the cone, then it releases that energy on the forward direction of the cone, thus giving the cone a little help, would this be a punchier sound... Or, is that just a sealed box again... Would be interested in your thoughts on this guys... Frank...
How about top mounted ports in tower speakers. Would that help with the soundstage by "filling" that whole corner area with sound ? Just make sure nothing falls in there...
I have read all the comments on here from technical experts who are way more knowledgeable than me and a lot of it has gone straight over my head. My 804s are close to the side walls and plugging the ports has helped tremendously with a woolly low mid boomy, bloaty sound problem. I love the sound now, albeit I am losing a bit of bottom end, but the sound is way better. By plugging the port on the front of the speaker, does this turn the speaker into a sealed box? And does this make the other drivers have to work a lot harder? Is it safe? Thanks.
So my question is what is a proper preamp to amplifier to mixer hook up. I write and play music for the love of it. And just want my sound to sound live and clear. But I do have a small room size for my set up. I do share the signal with a home audio receiver.
I read a book by a Dr Bailey who produced a design for a transmission line speaker back in the 1960's It was a design taken up by IMF in the UK who produced some of his earlier designs. His latter design had a lattice of a triangular path which was, he said aimed at reducing internal cabinet resonance. Infinite baffle designs usually had to be quite large to reduce the affects of compression and vacuum within a speaker. The concept of a reflex design was to reduce the affects of compression and vacuum within a cabinet, to produce a smaller speaker and extend the bass response. The design was renowned for reducing definition due to the problems of phase cancellation. I always had a large living room so I favoured transmission line designs with a separate high quality reflex speaker, sitting on top for the quality of sound in the upper frequencies. I spent many years in the Hi Fi trade and researched a lot of designs and our company produced the JR 149 which as you might know was designed by Jim Rogers who produced the legendary LS3/5a design used by the BBC. I still have a pair of Bowers & Wilkins DM4's and a pair of Keff B139 bass units. I hope to resurrect a pair of Transmission line speakers one day. I don't like Reflex speakers because as you say they lack definition. Thank you for your informative videos. Jeremy Travis former buyer for Teletape London
If I was to just drill a hole in the front of a speaker box to make a port without putting a tube in the port, like the speaker in your video, would that help the bass to come out or would it end up causing cancellation? I'm just wondering if a port can be just a hole or does it really have to have a tube in it that's tuned?
just looked thru some comments ( about 30 + ) didn't see anyone mention ' Thiel / Small' one of if not the first computer type speaker box/ port designs.... My Koss speakers ( 1978 1020 ) Koss claimed were the first to use this development. Seemed to work, the Stereo Review mag , Sept '78 > had a comment ' response curve flat + - 2 from 20 to 5000 hz'.... (closer to an amp than most speakers, even Advents of the day.my thought.) and distortion ' among the lowest we have yet measured' PS the Koss were fairly large, the mid range 1020's 33in high, 15 wide - 10 in bass with 2 front ports. Just as a guess, ported designs seem very common today.
The main reason why the ports are at the back is the mentioned sound they (sometimes) make. It is simply an artifact from air being pressed trough a tube, the entrance of the tube act a little like a whistle. Positioning it on the back hides it a little. The phase of the ports can be adjusted by the lenght. Simpified, the volume of the air in the tube has a mass and the the air inside box acts as a spring. If you have a spring and a mass you have a resonator which is allso a low pass filter. Those of course shift the phase of the signal and the signal can be in what ever phase the designer wants it to be at a certain frequency. A second resonator close to the resonance ferquency of the driver adds some complexity to the whole system, which will not make the design process easier. The more easy (controlled) way to archive the same are passive membranes but you have less possibilities to modify the parameters.
Hi Paul. I have a pair of Roland DM-20 front ported. Because I'm curious I pulled them open and found them empty except for the built in amp. I decided to stuff them a little bit with some pillow material. These are monitor speakers used, and was wondering if filling them is OK? They sound good, especially once I took them off the floor. Should I not have stuffed them, or does it not matter? I use them for listening to music, not mixing or anything. Thanks!
Intuition tells me placement is even more important for rear ported speakers as they are "playing the room" more (back wall reflections). Same for dipoles, magnetic planar, electrostatic, open baffle, etc. True or false?
Read the second chapter of of Vance Dickason's Loudspeaker Design Cookbook. It's is the worse transient response (time delay) that is the problem. There is always a delay and the inherent inertness reveals itself with complex percussion music. Also the ported enclosure exhibits less control on the woofer especially below the port resonance.
And here I thought you were going to speak loudly about Port wine. 😄 Kali Audio purports (NPI) to have solved the port 'chuffing' issue with their front port design. You might look into that if you are curious.
a lot of times if a port is chuffing its too small of a port. this happens a lot when manufactures try to use them to boost output and keep cabinets small. The air speed should be kept as low as possible. on low power setups this isnt that hard but as you keep adding more power it becomes increasingly difficult to achieve.
I think ports can be fantastic. I have a set of Paradigm studio 100's v.2. They have a front port. My subwoofer sitting next to it is never on unless I am watching home theater. The 2 8" woofers play nearly flat down to 39Hz. That ain't bad for the size...
Whether on the front or on the rear, the port is designed the same. At low frequencies the placement is not critical, since the wavelengths are long, so it can be put on either side. At frequencies below the port resonance there is indeed an issue with anti phase and cancellation and you get a steeper roll off. At the port resonance the driver does not move as it experiences anti resonance, while the output is coming from the port alone. Finally, at higher frequencies the port becomes decoupled and the behavior is the same as for a closed box.
Ports box is more produced Louder bass than sealed box but there is delay bass frequency comes out. Sealed box is always had smaller box needed and more accurate bass than port bass
There is also an added bonus to rear ported speakers, in that it's much easier to control bass intensity. It's mostly a given that speakers are best positioned at good distance from a front wall, that is, the wall behind the speakers. However, with rear ports it's possible to use the wall to stratigically enhance lower frequency performance. That can be particularly useful with overly lightweight, or higher frequency orientated speakers.
At tuning frequency the port is at 90 degrees out of phase with the driver. At the upper resonance is where the phase is perfectly aligned between the driver and port. At the resonance below tuning freq of port they are 180 degrees out of phase and the port and driver cancels each other like a dipole. The port is basically loading the driver at tuning freq of port.
It's been my observation through the years that I prefer rear-firing ports as opposed to front firing port. IDK if the bass slams into the corner of the room behind the speaker and has more wave-length to travel or what. I was skeptical of my Kicker's Sub-box having a huge side aeroport, but it doesn't seem to effect any sound quality. so... IDK.
Most port designs take advantage of what is called "helmholtz resonance", much like what produces the sound in a pipe organ. By tuning the port/box/woofer combination, one can use this phenomena to produce bass notes at lower frequency and higher spl than the woofer could in a sealed box at the cost of (usually) a larger box. At least that's how I understand it.
Can we say that a studio monitors with ports gives us different bass frequencies than are actually recorded?... so treating the room or blocking the port does similar things... I use the monitors very quietly because of neighbours, so will blocking the ports take my room out of the equation?... thank you :)
G.day brother what would u recommend in my case.I want to build a low mids box for my car audio use if 6 12” should I build a ported or seal box plz note that the boxes will be facing outwards back the back door window
@@steve5662 the only way to take the room out of the equation is to wear headphones
@@steve5662 Your studio monitors are designed with the port in mind, blocking it will likely give you a less accurate response.
"Shift Registers" at 4:14.... Been a while since I heard that term. Paul must be an old assembly language geek ;D
dcairns61 I think most CS students can relate 😜
Every programming language has bit-shift operators. Although it's generally true that you can only take advantage of the carry bit and use circular shifts in machine language - unless the compiler is intelligent and can understand that sequences like this can be implemented with a circular-shift instruction:
#define MSB_MASK 0x80000000;
int Cbit, shiftreg;
Cbit = shiftreg & MSB_MASK;
shiftreg
and JK Flip Flops too!
These videos are awesome, I'm learning many things I've wondered about for years.
Love this channel I am learning a LOT.
A joy listening to you everyday. Thanks.
Respect a man who uses shift registers to explain something.
Glad to see you're promoting the elac line I have a set of UF5 Towers and the UB5 bookshelves and hoping in the near future to purchase your Sprout 2 for my UB5's great job🎧🎶
I've recently been doing plenty of experimentation with ported box designs, including making my own 6th order bandpass box, and here is what I've learned about how ports behave.
They are in fact in phase with the diaphragm, due to their resonance their phase is inverted, causing them to add to the air displaced. If they subtracted, there should be an output dip either side.
This also causes an impedance dip, as the pressure within the box, experiences a peak caused by the added displacement. The driver moves slightly less due to the pressure, and causes an impedance dip as EMF decreases voltage being fed back to the amplifier.
Efficiency is increased as power is "shifted" from moving a diaphragm with relatively high mass to a tube of air resonating, with a relatively low moving mass.
Ported boxes have a steeper roll-off than sealed, as the port doesn't allow pressure to build up lower than its resonance. Low frequency air flow may come and go as it likes. It behaves sealed at higher frequencies, however only reflected waves come through.
Due to bass having an inherent non-directionality associated with its creation, the speaker box is simply adding or subtracting the local air pressure around it. Phase from front to back shouldn't matter. Enclosures where it does are referred to as "dipoles".
Port surface area is relative to length for tuning, possibly why front ported boxes have longer ports is due to a greater surface area attempting to eliminate "chuffing" with lower velocity airflow.
As far as I'm aware passive radiators behave like ports, though without chuffing, are less efficient, and from what I can tell work better with smaller boxes than ports.
Transmission line speaker enclosures work by having a set transmission line length, usually tuned to either 1/4 or 1/2 wavelength of the desired tuning frequency, feed the rear wave down a tube with said resonance. Port width is usually equal to the driver surface area and constant along the line, unless a tapering/horn loaded design is used. The effect on the air from thought experiments is like hanging a weight from a bungee cord, move your hand at the resonance of the weight, and although your hand is moving only a 1/4", the weight may be moving 1" or more. This works similarly to a ported box, though requires much more space. Generally transmission line boxes reach the lowest notes, though this may be due to them performing as dipole enclosures down low.
Dipole enclosures (also from thought experiments) effectively add a springy moving mass to the driver, lowering its resonance, which improves low end. The distance between the front of the driver and the rear creates the pressure differential, and therefore sound.
I kinda fell half asleep whilst writing this, so hopefully it makes sense
I see that you answered my question about passive radiators , Thanks. I was thinking on smaller speakers like the Vanatoo T1 and T0.
Dude , your off in left field with all that.
yes, but i'm enjoying his dancing in left field too... he's giving you some insights into other ported designs...
Arghhhhh! 6th order, as long as you know the phase response will be pants!
"They are in fact in phase with the diaphragm, due to their resonance their phase is inverted, causing them to add to the air displaced."
This is not true. At the precise resonant frequency, resonators respond IN PHASE to the driving function. Thus port emissions exactly at their resonant frequency will tend to cancel the woofer front wave and produce a narrow dip (notch) in the response.
Resonant systems exhibit a large shift in phase response, comparing at frequencies just below and just above resonance. Ultimately, an undamped system can exhibit nearly +/- 90 deg. phase shifts across a narrow frequency range.
In the region below resonance, the port can add boost to the woofer, but at or above resonance it tends to partly cancel the woofer front wave. If you do careful response measurements at small frequency steps for a ported speaker system, you may find significantly uneven results.
I just listen with my ears and that determines which speakers I like. I have both ported and sealed speakers. Best of both worlds.
Thanks Paul. Also, I really like your ending music.
He seems really nice.. and it's rare to be that humble and open as an executive (which I think he probably is)
Great video and I learned a few more things.
I see why closed subs has an advantage being active.
Thanks for sharing some magic of acoustics.In phase & out of phase sound production.
Very nice explanation.I learned many things.There are also down ported speakers like Wharfedale diamond 200 series and diamond 11 series (no chuffing noise at all)!!
The pressure inside a ported box is actually higher than a sealed. Low frequency waves actually go through the box a whole lot easier (below the tuning frequency of the enclosure, Fb.), this is called unloading. Below Fb the speaker increasingly "sees" no enclosure at all and will rolloff at ~24dB/octave. To avoid damage to a vented box with somewhat high Fb you need to highpass the frequencies below Fb as these will cause excessive excursion to the driver.
Port "chuffing" can be largely avoided by simply decrease its air velocity to below 17m/s. Many use flanged ends to help alleviate this problem as well. A well designed port/enclosure will won't have these issues to any audible degree.
A T/L and vented enclosure is not the same thing. Front port or rear ports really does not matter at all in a technical perspective. The wavelengths at low frequencies are so long that the port placement only amounts to a fraction of a frequency cycle's phase difference. You must have some distance (normally at least the vents diameter) between the wall and the backside of the enclosure which can lead to issues if you try to hang it on a wall or something. The main reason they place the vent at the back is to be able to save space really.
Futhermore, a vented enclosure is by itself more efficient and has lower non-linear distortion than a sealed enclosure due to less excursion around Fb. This of course increases the maximum output of the driver within its voice coil thermal ratings.
The only thing that a sealed enclosure is better at: as mentioned, the actual group delay/phase shift. The vent cause a phase shift in its passband which increases its group delay in these frequencies. This group delay's audibility must be seen in relation to the actual frequency. At 50Hz a full period is 20ms (1/50=.02s), while at 25Hz a full period is 40ms (1/25=.04s). With certain alignments the group delay can exceed a full period, at some point it starts to get noticable and this is what people refer to as "sloppy bass".
A lot of times this issue is fixed by simply equalizing the frequency response as group delay is a derived function of the magnitude and phase response. The enclosure-inherited group delay of a vented design can be fully corrected for with FIR-based signal processing. In my opinion, the vented enclosure is usually far superior to a sealed box, especially if you got a powerful DSP / room correction. Note that not all drivers are suitable to use in vented enclosures, most high Q-drivers should be avoided for example.
Man do you know your stuff!
Thank you Mr. Paul. Nice explanation as always.
Paul I really enjoy watching your CZcams videos and the information you give. I would love to visit your factory one day!
You would be most welcome.
Very well explained, thanks for the video :)
Thanks for the detailed explanation - really informative
I recently purchased Kali Audio front ported Studio Monitors. I used to have the Yamaha HS8's, but the 8" woofer with the rear port produced to much boomy bass as my studio is small thus my speakers are forced to be closer to the wall. The front ported Kali Audio monitors with 6.5in woofers and front port design fixed my issues perfectly. In addition they have a trim pot to compensate for speaker locations and room environments. So sometimes front is better depending on the the acoustics of your listening room.
I was just trying to figure out what "that hole in the front" was, I felt like a dumbass for calling it a hole haha
ooh, fancy little Elac speaker, Jawhol ! I have passive radiators in the front of my 1978 Philips AH-487 speakers. It looks like a woofer membrane without the magnet and the voicecoil etc
I wish you’d do a comparison of sealed , ported , and passive radiators.
I’m personally a fan of how passive radiators sound. But there’s very little information available on them
Paul reminds me so much of my dad... but happier
Great explanation 👍
Paul, your description of how a port works is much less pornographic than Zeos Pantera's attempts to explain why that hole is there and I thank you for that. There are books dealing with loudspeaker design and I'm sure my 'accountant' will let me buy one when the time is right (hell freezing over, apparently) but until then I'll have to rely on the insights of people who actually do this stuff for a living. I look forward to the new PS Audio speaker even if I know that it will be many multiples of that Elac bookshelf you held up at the start of the vid - thanks again for the video.
Whenever you have to deal with an accountant that tells you "when hell freezes over", remember that there is a town in Norway called Hell. It's not far from Trondheim. So "when hell freezes over" is probably somewhere in late october, early november.
Thank you for explaining speaker operation Physics.
I actually have had 2 different surround speakers series by Psb Audio with ports and found the number of ports made a difference as well. My current speakers have 3 ports and I also have port plugs.
Every port shifts the phase by 90 degrees at its tuning frequency, no matter on which side of the enclosure it sits. If it's on the back you usually lose a few decibels in the bass because the phase shift increases due to the time it takes the sound to travel from the back to the front. Wave lengths in bass are big in comparison to the dimension of the enclosure therefore they bend around the edges (spherical radiation). But ports also let a small amount of mids pass through which is perceived as distortion. In the mids the sound waves are smaller and don't bend around the edges. Therefore they don't reach the listerner if the port of a mid-woofer is on the back. With a port on the front this distortion might lessen the sound quality. The solution: port on sides, top or bottom as near to the front as possible.
The huffing and puffing noises are generated by turbulences of the air flow inside the port and on its edges. Therefore those Elac speakers have a port with round edges. If the diameter of the port is too small the air flow gets too fast and turbulences occur even on the surface of the inner wall of the tube. The cross section of the port should be at least one fifth of the effective piston area of the driver. Even better is one fourth or more but the length then might become too big for the same tuning frequency. The standing wave inside the tube becomes a problem then.
Before I discovered your "Ask Paul" series I started a similar podcast in German, apart from most of my other videos being in English. Im currently translating my first few episodes into English but it takes a lot of time because they were not scripted. On many of them CZcams's automatic subtitle function didn't even work. (The German version seems to be not that good yet.) If I gathered some more subscribers from the English speaking world it would maybe motivate me to speed up my work.
Source of all my knowledge: German DIY loudspeaker magazine Hobby HiFi.
Thank you for that interesting comment 4 years ago, Marius 🤗
"in your little shift registers"-Paul is an iconic engineer
When properly designed and manufactured, ported speakers can be used in two different ways: if you have the room to have your speakers out from the rear wall, as in on stands, rear ported speakers will be your best bet. If you don't have the room, and may even have to wall mount then a front ported design would be your best bet.
When I eliminate the ports from the speaker box I enjoyed a lot than before .Luv u Paul . u are great .
I have a pair of B&W 804 D3 floor standing speakers. They sit 3 feet from the back wall but are close to the side walls. I didn’t like the mid bass boom I was getting so I have now put the supplied foam bungs in the ports that are on the front of the speakers. They sound way better now. If I add a sub (or two) to extend the bass down, would I still get any bass bloat in the room, seeing as the 804s are now “sealed”? Thanks.
Thanks for my learning.
These feel like hanging out with your grandpa on a weekend and he's teaching you about something your parents didn't want to learn but you're super interested in
My grandfather taught me how to break the windshield on a car with a jack handle. then flip his lawyers business card at the shocked driver. He hated car horns.
@@sansocie .....Nice guy...
What is your thought on Passive Radiators?
Very interesting subject. Vented speakers have (as you know) been around a long time. 1960's vented systems did tend to sound "unnatural". A.N. Thiele and R.H. Small research into vented designs was used by, I think, two companies in the early 1970's. Electro Voice and Ohm Acoustics. Venting took three major types; ducted ports, passive radiators (drone cones) and transmission line (labyrinth). I auditioned and purchased Ohm model L vented systems in 1978. I still enjoy these speakers today. Old argument was... acoustic suspension speakers sounded "tighter" than vented systems. My Ohm H speakers have an 8" woofer with a 12" passive radiator and bass is tight, deep and very satisfactory. I guess the main advantage of venting speakers is to provide deeper bass in a smaller box. Perfect for teeny weeny NYC apartments.
Nice video Paul. How about ported speakers vs passive radiators?
passive radiators is basicly a port simulator. But since its smaller than a port you can get small airspace and the same output
I have audiology Grason Stadler 162 with altec 418b loudspeakers. There is a lot of clarity with highs and no mid and low range. I was wondering if I should port the sealed enclosure.
I prefer the curve of my ported subs. High at 30hz and steep roll off from 40 to 80 hz. I've spent my life chasing after perfection and to me this is as close as I can get. They lack the punch of a flatter curve, but I'll take that trade off. There is only one song I know of where my setup has an obvious lag between notes and it bothers me but I would still not trade it for anything else, especially not a sealed subwoofer. So much of this has to do with what music you listen to, and I think when people have disagreements they sometimes fail to take that into account.
I can appreciate the use-case scenario. I personally prefer using a bigger amp and more EQing to get a similar curve from a sealed enclosure. I’m sure they’re out there, but I’ve never heard a ported enclosure with good subsonic extension. Ports can create phase issues that can be very difficult to address. Of course, if power limits at a large venue are limiting, a ported enclosure would make sense.
as an electrician i think of ported speakers as LC oscillator , the port is the inductor and the box the capacitor.
you may also think of a spring (box) with a weight (port) attached to it.
Ports are a way to alter the physics needed of enclosure size to produce sufficient bass. I used to own a few of the Dunlavy speakers that were all sealed boxes - no ports at all. And they had terrific bass, but they were large enclosures (not very high on the wife-acceptance scale). If you didn't mind your speakers almost as large as your refrigerator, the bass was articulate, fast, and very real, with none of the problems with ports. Still the best I've ever owned.
Would like to say love your videos I have a question that is off Q but just curious your opinion I have mainly vintage Sansui equipment my speakers are SPX 9700 and SPX 9000 do you feel bet they have the quality of today's speakers
Because you used the word "vintage:" about 45 years ago, in the early '70s, I went to the Far East courtesy of the US Navy. In Hong Kong I purchased a pair of Wharfedale. I listened to everything I could, and back then, all of the Japanese speakers were really bad. Just terrible. Their electronics were much better. Hopefully Japanese speakers are better, now. I prefer American speakers. I suggest that you simply: trust your ears! Take some, a few, of your favorite albums and Compact Disks to a good hi fi location such as Magnolia, and Hi Fi salons, if you can, and compare the sounds from the various pieces of equipment. Try to purchase the best, most pleasing sound TO YOU, that you can afford. And, keep an open mind! It's possible that your current speakers remain satisfactory and pleasing TO YOU!
Do they still make Acoustic suspension speakers where the air in the box is used as the restoring "spring"? I have some old AR speakers that used this design and while they are less efficient than other designs, they very good bass response.
I had a pair of monitor audio rs6.
They had a port at the front and one at the rear.
They were actually nice sounding speakers
What most people seem to forget is that sealed speakers also have a port.
That is the driver itself. The driver's backwave will resonate and reflect back through the cone in a number of rather unpredictable ways. And that is with all the stuffing in the world too.
Of course if you set a whole room aside for the speaker we are close to infinite baffle and the effect will be very small. But that is fantasy land for most speakers.
Rear ports are more picky in regards to room placement. If a rear ported speaker is placed too close to a wall, there can be either an increase in bass amplitude or a cancellation of lower frequencies due to reflections and phase alterations of the sound leaving the port. Make more room behind them, and they will have smoother bass characteristics. Front ported speakers do not experience this problem, so they can be placed closer to walls. But because the port is facing the listening space, it might be easier to hear the port noise. I've got some rear ported bookshelf speakers, and they're pretty close to a wall, so I ended up plugging their ports. Their bass sounds muuch less boomy. And the reduced bass range is being taken up by my subwoofer. It's a win-win.
can that port shuffle if it's made of silicone ( like KEF LS50 ) ?
Sealed has a cleaner sound but requires more power. I personally think it depends on what kind of music you listen to. I dont know. I like a sealed box for rock and metal. But if you get into the hip hop style the speaker cant react fast enough and starts to bog. If that makes any sense. Love all your videos Paul.
NTH Welding , I had an old vintage pair of Advent 3 way speakers with a 12 inch woofer, 4 inch mid and 1 1/2 inch dome tweeter, sealed.
I compared them to a set of equal speakers made by Cerwin Vega, no comparison, the Vegas blew them away. but on the other hand, the Advents although took more power to run as loud had a much tighter hitting bass frequency, so I just used all four speakers in the same room. the sound was great!!!!! it really comes down to if you have tube amps or digital amps and what type of music you like.
Firstly, thank you so much for these videos. I've only just dicovered them.
Now I am.going to ask a very basic and possibly, naive question. What is possibly better between a scoop bin and a rear mounted speaker. 'W Bin'??? I've owned scoop bins before, but never a rear mounted speaker. Is one better suited to a certain situation? Size of room etc.
The port has an air mass that is suspended with the airvolume inside the box.
When this mass reach resonance due to the triggered soundpressure from the woofer, it starts to resonate. At resonance, the air in the port goes out when the woofer does. This will enhance the bass level. The wavelength at 50Hz is about 7 meters, so it does not matter if the port is in front or on the rear.
However, at lower frequencies than the ports resonance frequency, the air in the port starts gradually to get sucked in while the woofer goes out.
Conversely to having a port. Does the sealed speaker with the compression and vacuum going with the cone operation, vacuum when out, pressure when in, actually create a quicker stop and then quicker restore of the cone and reduce vibrations as the cone goes back to its central position. Thus making the base truer to the original as it is now self controlled. Overthrow and sluggish return are now self regulated by the size of the box in relation to the cone movement.
Hi Paul, a typical tuning frequency for a port will be something like 20-40 Hz. What's the wavelength there? How does that compare to the front to back box dimension? Thanks!
Thanks for the videos! I have a question about speaker wire. Should my left and right channel have the same, short length from the amp?
Thanks for the answer! But high end my speakers are not. 15" Pyle drivers, Horn tweeters, unmarked mid range in a plywood box with a massive rear bass port. They're designed to be efficient, at 10 watts they are deafening.
But, anything I can do to improve the quality that they're reproducing I will do, especially if it's as easy as measuring and cutting the existing speaker cables.
Yes. I find if you make one speaker wire shorter your stereo image will shift toward the speaker with the shorter wire.
Not if you use adequate cable. I use 6mm to make sure.
In theory, different lengths cause phase shift between left and right. Reallity is that the amount of phase shift is so small as to be undetectable. Lets do the math. Lets say your left vs right lengths differ by 5 meters. In copper, electricity travels at about 280,000,000 meters/second. The time difference of a frequency starting at the left vs the right (Time Difference Td) = 280,000,000/5 = .000000017 seconds.
At a frequency of 1000 Hz the period (P) of the cycle is 1/1000 = .001.
Phase Shift (Ps) = 360 * Td/P Ps=360* .000000017/.001 = .00612 degrees
This Phase shift represented as a percentage would be .00612/360*100 = .0017%
I highly doubt that this is detectable. If this were aubible, we would have to listen to music in precisely the center of the two speakers and have only one ear placed directly precisely in the middle. The distance between our ears would cause much greater phase shift than the 5 meter wire difference.
I prefer sealed over ported, but some ported models are great also. Rear ported designs are much better than front ports, to me anyway. Sealed just has a cleaner smoother bass and just plain sounds better I think.
Ive got a question for Paul McGowan and viewers out there. I'm building a 2x12" speaker cabinet for a 100w peavey valveking head and wondered should I port the cab? I don't really want too as it will be a closed back cab, but does and will it make a huge difference in the sound if I do? And if I put a small hole in the cab say 10-15 or 20mm for example just to let the speakers breath/move properly within the cab and not let out alot of noise will this help with speaker over all speaker perfomance and or sound? Thanks and love your videos.
I really hope you didn't port that thing
Actually the port sound output is in phase in its adjusted frequency. Due to resonance of the enclosure and the "Piston mass" inside the tube.
Lets say you want to adjust the bass reflex supporting frequency to 35 Hz. You got a 50 L Box, than you need a round port approx 4" width times 12" length. Big floor standing speaker.
Out of the adjusted frequency the "Air Piston" in the tube can not move properly, or even not at all.
The fuction of the port increased if approaching the frequ. and its decreasing if leaving.
But in this case it doesnt matter in my eyes, if the port is in the front or in the back.
Because the wave length at 35 Hz is 10 yarts and you got a 1' deep Speaker maybe (front to back). So the back port would be 1/30th out of phase reaching your ears.
Bass is emitting nearly 360° the same around the speaker. so doesnt batter to me.
A passive Butterworth Frequency cross over for example, with -6 db per octave, generates a 90° delay in Phase in the low pass way, thats nearly 4' - Bass/Mid separation at 300 Hz . However it is the commonest frequency cross over. That tears apart the exact imaging of the stage arround the crossing frequencies.
Some very smart invetors and developers build speakers that wave no delay in Phase, absolutely time coherent. A giant step towards natural sound play back.
cheers.
Jean Katana Above the the tuned frequency the air mass within the port cannot move freely, but below it, it can.
This is one of the caveats of ported loudspeakers, below the tuning frequency, of the port, the cabinet and port offer no control over the motion of the cone. The driver unloads, excursion shoots up with falling frequency, and the output rapidly reduces.
thank you for this video, sir
very informative and constructive.
plus the helpful comments.
an exceptionnel 'channel'
free of blah. blah. if you allow.....
G.day I’m all the way from Guyana I need to know if I should use a Ported or seal box for my low mids,plz note that the boxes are facing out the car by the back side window
What is your opinion if you have one of Bi-Polar speakers?
From personal experience... I listen nearfield with the speakers at ear level. When I had front ported speakers? When certain notes were hit, it was like sitting in front of a hair dryer set to cool. On cold nights I would get cold air blown in my face. So... rear ports have another good purpose. I prefer sealed or passive radiator speakers. More accurate sounding.
Med always comes out of ports too (but at a really low level). But it's enough to effect the med tone and make the voice sound wrong. But if the vent is at the rear of the speaker the med (from the port) is less heard. That's why I reckon most ports are rear.
I really enjoy Paul's authenticity! ...spite the fact the transmission is emitting from Boulder, Colorado! Yikes!
Interesting subject guys...
What are your thoughts on a down firing ports on stand mounted, floor standers... Any strengths in that idea?
Or is that a no go area? If yes, why?
I know most rear ported speakers are straight through into the speaker cabbinette, so what about a series of baffles?
Would that help or just hinder air escapement?
I have been wanting to design my own speakers for some time, this is why I'm asking the question...
One other thought, is what about some form of diaphragm mounted within the port, thus pushing the speaker cone forward when its on it's forward travel...
So, in effect, the diaphragm is charged on the backward direction of the cone, then it releases that energy on the forward direction of the cone, thus giving the cone
a little help, would this be a punchier sound...
Or, is that just a sealed box again...
Would be interested in your thoughts on this guys...
Frank...
How about top mounted ports in tower speakers. Would that help with the soundstage by "filling" that whole corner area with sound ? Just make sure nothing falls in there...
I have read all the comments on here from technical experts who are way more knowledgeable than me and a lot of it has gone straight over my head. My 804s are close to the side walls and plugging the ports has helped tremendously with a woolly low mid boomy, bloaty sound problem. I love the sound now, albeit I am losing a bit of bottom end, but the sound is way better.
By plugging the port on the front of the speaker, does this turn the speaker into a sealed box? And does this make the other drivers have to work a lot harder? Is it safe? Thanks.
So my question is what is a proper preamp to amplifier to mixer hook up. I write and play music for the love of it. And just want my sound to sound live and clear. But I do have a small room size for my set up. I do share the signal with a home audio receiver.
Chuffing - exactly!!! I walked away from ported speakers and subs. I prefer sealed or passive radiator designs.
I read a book by a Dr Bailey who produced a design for a transmission line speaker back in the 1960's
It was a design taken up by IMF in the UK who produced some of his earlier designs. His latter design had a lattice of a triangular path which was, he said aimed at reducing internal cabinet resonance.
Infinite baffle designs usually had to be quite large to reduce the affects of compression and vacuum within a speaker.
The concept of a reflex design was to reduce the affects of compression and vacuum within a cabinet, to produce a smaller speaker and extend the bass response. The design was renowned for reducing definition due to the problems of phase cancellation. I always had a large living room so I favoured transmission line designs with a separate high quality reflex speaker, sitting on top for the quality of sound in the upper frequencies.
I spent many years in the Hi Fi trade and researched a lot of designs and our company produced the JR 149 which as you might know was designed by Jim Rogers who produced the legendary LS3/5a design used by the BBC.
I still have a pair of Bowers & Wilkins DM4's and a pair of Keff B139 bass units. I hope to resurrect a pair of Transmission line speakers one day. I don't like Reflex speakers because as you say they lack definition.
Thank you for your informative videos.
Jeremy Travis former buyer for Teletape London
Love this Channel too.Like.
I mainly listen to Metal music. What kind of sub would you recommend. Ported or Sealed?
If I was to just drill a hole in the front of a speaker box to make a port without putting a tube in the port, like the speaker in your video, would that help the bass to come out or would it end up causing cancellation?
I'm just wondering if a port can be just a hole or does it really have to have a tube in it that's tuned?
If designed properly transmission line speakers can have very low bass output though the cabinet size will have to be fairly large.
just looked thru some comments ( about 30 + ) didn't see anyone mention ' Thiel / Small' one of if not the first computer type speaker box/ port designs.... My Koss speakers ( 1978 1020 ) Koss claimed were the first to use this development. Seemed to work, the Stereo Review mag , Sept '78 > had a comment ' response curve flat + - 2 from 20 to 5000 hz'.... (closer to an amp than most speakers, even Advents of the day.my thought.) and distortion ' among the lowest we have yet measured' PS the Koss were fairly large, the mid range 1020's 33in high, 15 wide - 10 in bass with 2 front ports.
Just as a guess, ported designs seem very common today.
The main reason why the ports are at the back is the mentioned sound they (sometimes) make. It is simply an artifact from air being pressed trough a tube, the entrance of the tube act a little like a whistle. Positioning it on the back hides it a little. The phase of the ports can be adjusted by the lenght. Simpified, the volume of the air in the tube has a mass and the the air inside box acts as a spring. If you have a spring and a mass you have a resonator which is allso a low pass filter. Those of course shift the phase of the signal and the signal can be in what ever phase the designer wants it to be at a certain frequency. A second resonator close to the resonance ferquency of the driver adds some complexity to the whole system, which will not make the design process easier. The more easy (controlled) way to archive the same are passive membranes but you have less possibilities to modify the parameters.
For me there’s nothing like aperiotic ported speakers (Dutch audiolab largo pro speakers). They sound amazing!!
I want to know what's with open baffle speakers if there is no box?
Hi Paul. I have a pair of Roland DM-20 front ported. Because I'm curious I pulled them open and found them empty except for the built in amp. I decided to stuff them a little bit with some pillow material. These are monitor speakers used, and was wondering if filling them is OK? They sound good, especially once I took them off the floor. Should I not have stuffed them, or does it not matter? I use them for listening to music, not mixing or anything. Thanks!
Can enyone tell me there to find real info on: placing of bass reflex port.
(Dods it matter or not. There is allot of confusion on this)
DMC time windows have front ports. Sounds nice too.
I have a great fan of passive radiator speakers.
hahaha set that aside in your shift registers. people this is a man who knows his digital electronics.
what about dampened ported speakers ?
Intuition tells me placement is even more important for rear ported speakers as they are "playing the room" more (back wall reflections). Same for dipoles, magnetic planar, electrostatic, open baffle, etc. True or false?
Is that a frosted glass behind you?
How about the bottom ported ones?
Paul's a visionary
Is it ok to partially block my ports to cut the bass down a bit at night? I use Klipsch rear ported speakers.
What do you think of horn loaded stuff?
Read the second chapter of of Vance Dickason's Loudspeaker Design Cookbook. It's is the worse transient response (time delay) that is the problem. There is always a delay and the inherent inertness reveals itself with complex percussion music. Also the ported enclosure exhibits less control on the woofer especially below the port resonance.
And here I thought you were going to speak loudly about Port wine. 😄
Kali Audio purports (NPI) to have solved the port 'chuffing' issue with their front port design. You might look into that if you are curious.
how do I calculate optimal port dimensions (length and diameter for a round port) to gain maximum efficiency and maximum output for a given subwoofer
a lot of times if a port is chuffing its too small of a port. this happens a lot when manufactures try to use them to boost output and keep cabinets small. The air speed should be kept as low as possible. on low power setups this isnt that hard but as you keep adding more power it becomes increasingly difficult to achieve.
I think ports can be fantastic. I have a set of Paradigm studio 100's v.2. They have a front port. My subwoofer sitting next to it is never on unless I am watching home theater. The 2 8" woofers play nearly flat down to 39Hz. That ain't bad for the size...
Whether on the front or on the rear, the port is designed the same. At low frequencies the placement is not critical, since the wavelengths are long, so it can be put on either side. At frequencies below the port resonance there is indeed an issue with anti phase and cancellation and you get a steeper roll off. At the port resonance the driver does not move as it experiences anti resonance, while the output is coming from the port alone. Finally, at higher frequencies the port becomes decoupled and the behavior is the same as for a closed box.
Would an elliptical port increase the frequency range of the 3 to 5 dB bass boost?
No.
With a port having a delay time, I'd expect a peak at whatever bass frequency matches that wavelength.
Not if it's tuned correctly
Ports box is more produced Louder bass than sealed box but there is delay bass frequency comes out.
Sealed box is always had smaller box needed and more accurate bass than port bass
There is also an added bonus to rear ported speakers, in that it's much easier to control bass intensity. It's mostly a given that speakers are best positioned at good distance from a front wall, that is, the wall behind the speakers. However, with rear ports it's possible to use the wall to stratigically enhance lower frequency performance. That can be particularly useful with overly lightweight, or higher frequency orientated speakers.
At tuning frequency the port is at 90 degrees out of phase with the driver. At the upper resonance is where the phase is perfectly aligned between the driver and port. At the resonance below tuning freq of port they are 180 degrees out of phase and the port and driver cancels each other like a dipole. The port is basically loading the driver at tuning freq of port.
It's been my observation through the years that I prefer rear-firing ports as opposed to front firing port. IDK if the bass slams into the corner of the room behind the speaker and has more wave-length to travel or what. I was skeptical of my Kicker's Sub-box having a huge side aeroport, but it doesn't seem to effect any sound quality. so... IDK.