Transmission line loudspeakers

[@Bassotronics]

I love Transmission line enclosures. I use a specially designed one for my car. Its a cardboard 18” subwoofer tube and inside that same tube is a PVC system which consists of 100” long 4” diameter tubing. It plays well down to 15Hz with authority and sounds like I had two subwoofers instead of one. For vehicles I prefer tube because they are much lighter weight, don’t require bracing and are not prone to wall vibrations like the common bulky heavy square enclosure of which you have to brace the hell out of to keep stable as well as use thick walls which all adds up to unnecessary weight.

[@MrEdsager]

I have a pair of Fried A/6's currently, and have enjoyed Irving Fried's designs for forty years! I used to receive his writings and had a phone conversation with him once. He was very strongly opinionated, and contributed in a major way to this hobby. Thanks Paul for the fine explanation of TL design.

[@sky173]

4:12 - *1000ft per second :)

[@patthewoodboy]

yep ..330m/s

[@johnmarchington3146]

A great video, Paul. Some decades ago now I had a friend who was the wood-working instructor at a local school and one Saturday we spent the day in his wood-working shop constructing a couple of transmission line cabinets based on the design by A. R. Bailey. I had bought two sets of KEF drivers, that included a pair of B139s. I remember some of the internal construction of the labyrinth was very fiddly and I was certainly grateful for the expertise of my friend in overcoming those difficulties. I was also very impressed with the results.

[@geoff37s38]

I built this design 40+ years ago. KEF B139 and T15 drivers.

[@joeythedime1838]

I own a pair of transmission line speakers, T+A CRITERION TCD 110 S. They are a bit unique as they also employ two mid-range units in the D’Appolito arrangement. They are a bit heavy at 130lbs each but they have a very nice bottom end and great voicing. Frequency range is 22 - 35000. I have a picture of the inside of the cabinet and it's amazing how long the transmission line tunnel is.

[@WorstUsernameInDaWeb]

i have no idea why youtube algorithm prefer to promote bulls*it from tiktok influencers rather than promoting great quality channel like this one. Thank you for your knowledge sir i wish you happy healthy and meaningful day for the rest of your life.

[@crazydave1996]

If I'm not mistaken a big plus from the use of a transmission line is that there is an amount of back pressure within the cabinet, meaning the woofer more or less responds as it would in a sealed box. This means you get the extended bass of a TL design but also the tighter mid frequency performance of a sealed speaker

[@ClaytonMacleod]

All ported designs control the woofer above the tuning frequency. It is below the tuning frequency where it becomes a floppy mess.

[@randomtube8226]

As much as I like transmission line enclosures. I like the tapped horn design more. Almost sounded like that was what was being talked about with the tuned in line phase. But I also really enjoy a good passive radiator enclosure. The amount of sound you can get out of a tight space is nice. I would really like Chris to take the time to explain this subject.

[@tomlademann2521]

tapped horn is essentially a tl, just with the woofer not facing directly outwards...

[@larrycooper7249]

Now I am convinced. I cannot watch anymore of Paul's Hyperbole. One should watch this channel for entertainment purposes only (1 foot per second)!

[@paulredding5347]

That is all he provides. Full disclosure I do own PS equipment and love it.

[@davidfromamerica1871]

I watch this channel for the questions asked and the Audiophile comments. Yes I read all the comments and replies. The true reason for this channel is for marketing purposes. Paul is in business to sell his audio equipment. Paul knows how to market his company using the largest potential marketing audience in the World. .KZbin. ✅ How Paul markets his products line is his business. Paul owns his own company, runs his own business. My only interest in this channel are the Audiophiles emotional psychological aspects of the experience of being locked up in the Asylum with them.

[@stimpy1226]

I met Irving Fried once when I was younger. He thought his speakers were better than everyone else's. His design concept was brilliant in retrospect.

[@Antoon55]

If sound travels one foot per second I can run faster than sound :)

[@bluefalcon69]

Thanks for mentioning Bud Fried. I'm using a 35 year old set of his 12" subwoofers and love them.

[@The4Crawler]

I still have and use the pair of TL speakers I designed and built in 1980. I replaced the original 8" drivers with some 10" TL specific drivers from SpeakerLab and have had to re-foam them about 9 years ago. They do use a lot of wood to make, I think I used 4 or 5 sheets of particle board for the pair. I spent a lot of time tuning them up. Also hand wound all the crossover inductors.

[@gt4viking789]

Hi Paul, is it fair to say that you are not really selling The Transmission Line principle here telling us, that speed travels at 1foot/second 😂 I’m a very happy owner of British made PMC Fact 12 speakers with an internal duct of 3 metres, which means that a low frequency note should be exciting the port by 10 seconds. I think your 1 foot reference could be a nice approximation to the speed per 1000th/second for sound. The only reason I believe that only a very few companies produce transmission line speakers is the complexity of getting them right. They deliver a tight,fast and ‘out of the box’ bass experience, which once you’ve heard is very difficult to match with any other speaker design. You are a great guy Paul and I always love to watch your videos 👍🏼 Greetings from the UK, Peter.

[@scottwolf8633]

The Mass of the air in the line couples to the Mass of the cone, lowering the Fs, while the pressure differentials between the outside air and line act as a restoring force. The classical superposition of line and cone add low frequency information. In a correctly implemented T-Line, as characteristically, "Tight, fast, clean", low end.

[@kellygrant4964]

Love my Meadowlark Kestrels.. transmission line. Once well placed they are astounding not only with the base but soundstage. I would have a hard time replacing them for sure. Pure joy for over 20 years of listening to the music they produce.

[@robertmoi8400]

Hi Paul, I love your channel, informative and you value our time by creating short and straight-to-the-point videos. My understanding of how ports works differ from your explanation though. From my understanding, the port only allows the speakers back wave to escape the cabinet below the tuning frequency that's why there is a steep roll-off below the tuning frequency. At the tuning frequency, the air inside the port resonates creating a sound that is always in phase with the front wave/speaker sound. I am unsure whether the air inside the port resonates due to pressure inside the cabinet or the back wave of the speaker. Above the tuning frequency, the air inside the port acts as a barrier for the sound waves to escape the cabinet/air inside the port is not triggered to resonate. Passive radiators should work similarly but tuned using a passive radiator cone weight instead of port air volume.

[@BoredSilly666]

Your a correct Robert, Paul at times shows his lack of knowledge of speaker design, although he does say it at the start. He didnt even mention the acoustic absorption inside at different thicknesses to filter out the mids so as your correctly say its the back wave Low Freequency that only escapes in phase out the port. Sheeps wool used to be used, these days its a different density of foam and thickness and different parts of the Line. I would have a pair of PMC BB6XD or something similar over a PS Audio Pair all day long. What annoys me is half the comments lap it up thinking Paul is so knowledgeable and correct when really that was a poor explanation with half the facts missing. I really like Pauls videos and watch most but sometimes hes way off the mark.

[@johndough8115]

Somewhere along my Journey, I believe I had heard that these long tube designs, were to create a way to simulate a much larger speaker box size. Think of a PVC tube. If you hung a 1ft long tube up.. and a 7ft tube next to it... if you hit both with a rubber mallet.. the longer tube will sound bassier. While vibration and air movement are different things... the air volume, does in fact matter, in producing deeper bass sounds... with these Ported "Trumpet" speaker boxes. That said, while a Ported speaker can produce lower bass potentials.. the bass they create is highly "Artificial" sounding bass. Its not what the studio intended you to hear... Not even close to it. Where as a sealed speaker, will reveal the actual sounds that you were meant to hear. Passive radiators, do in fact do an excellent job of creating extra bass thump, without the typical distortions, of a tuned port. The downside of a passive, is that they will not give you much bass at lower volume levels... and when cranked to very high volume levels, might be a bit too much bass. Their "Excitement" levels, are based on the woofers levels, and the "Weights" on the passives. You can deal with this... by adding an EQ to your system. You can pump up the bass levels to get your passives excited at lower volume levels... or you can reduce your bass levels... to keep the passives from being Too-Excited at those higher volume levels. Sealed speakers, have a sort of curve of their own. The bass is good at low to mid volume levels... but it REALLY POPS, at mid-high to very-high volume levels. The more power you feed them.. the more punchy and deep of a response, that you will get. From my experience... Ported speakers sound OK at lower to mid volume levels. Anything mid-high to very-high... and you get worse and worse sound output... as that artificial sounding bass tone, distorts and muddies the music. Each design has its own Positives and Negatives. Personally, I can no longer stand Ported speakers, at all. Once you hear a high quality Sealed speaker... and hear how natural bass is supposed to sound... you can never go back.

[@wilcalint]

How, or does, the "PVC tube" control the natural resonance of the speaker? If at all?

[@johndough8115]

@@wilcalint I do not know the technical meaning behind Resonance. That said, I dont believe it factors in. Your voice sounds deeper, when passing through a very long tube. And a shorter tube, will not be as bassy sounding. Remember, a Tuned port... acts like a sort of trumpet. When you blow enough air out of it... its designed to produce a certain bass TONE / Frequency. That tone, will always be the exact same tone... no matter what the speaker is actually playing... which is why its bass sounds "Artificial". A transmission line, is essentially just a ported speaker... but with a longer snaking pathway. Using that longer path, allows for a deeper bass tone response... and maybe a bit more energy... but its still just a glorified artificial-Bass-Horn. I believe PVC itself, has a potential to leak sound, and to vibrate... which I believe falls under the term Resonance. However, you could make the tube out of any dense material.. and it will function the same way. Its just a long tube with a tuned horn (flared port).

[@wilcalint]

@@johndough8115 "I do not know the technical meaning behind Resonance" Proper speaker design is all about controlling Resonance. Do note that speaker design goes all the way back into the emergence of the movie "talkies". The tirst movie theaters with "talking" movies emerged in the early 1930's. So the math and design for speakers goes all the way back into the 1920's.

[@vsalasarcr]

Greetings, I wish a happy new year to all of you.

[@D1N02]

I have some speakers that are a-periodic that is a bass port that is heavily dampened. I don't think it lets out a lot of air, it function more as pressure reducer making the box seem larger to the drivers. Cabinet still very stuffed. Really an intermediate between a closed box and a ported design.

[@BartholomewSmutz]

Is the Klipsch Folded Horn design in the Klipschorn speakers an example of a transmission line speaker?

[@scaryperson27]

I thought the whole point of a passive radiator was that it was supposed to act like a port and that it is out of phase. By the time the The air compressed by the woofer drives a passive, the inertia of the weight of the cone on the passive is delayed in its movement. You tune them lower by adding more weight thus making them move further and further behind the original waveform produced by the woofer. I am not an expert so I may be misunderstanding something

[@jked7463]

Hate to say it, but this in not your clearest explanation. The transmission line length is such that the out of phase rear output is now in phase with the front of the driver, but only for wavelengths that length of transmission line (and their harmonics). Fuzz is added to slow the speed of air in the line to shorten the line and widen the effective range and smooth out the response.

[@sudd3660]

you can not get extra bass for free, so only open baffle or sealed box is pure woofer output. there some new options like cardioid vents in the cabinet but i do not have enough information on it yet. passive radiators, bassreflex, transmission line all have drawbacks. sealed box with dsp i think is the best option, its small, goes low, easy to build and design. and none of the drawbacks.

[@morbidmanmusic]

Sealed vs baffle have different bass responses... theory blown.

[@sudd3660]

@@morbidmanmusic different do not mean worse, generally open baffle have less bass extension, but it does not compromise on sound quality.

[@PSA78]

Boosting bass with DSP typically add a delay as well, FIR might get around that.

[@sudd3660]

@@PSA78 yea, that delay is present in most cases, i definitely noticed that when doing narrow band adjustments. less of an issue in bass region, and having separate delay adjustment between drivers or subwoofers. FIR has less phase issues but adds processing delay as far as i understand how that works.

[@analogkid4557]

The draw back is, lower output and more distortion.

[@geoff37s38]

I built TL speakers 40 years ago based on a design by Dr. A R Bailey. I used KEF drivers and long fibre wool filling. They sounded excellent but not very efficient. The transmission line absorbs most of the energy from the rear of the driver and does not cause undesirable back pressure or resonances. Not much output reaches the port, only very low frequencies. Large boxes and a bit difficult to make, but worth the effort.

[@juststuff5216]

I've only been building t-lines exclusively since 1991, but the biggest misnome I find is stuffing them to the gills with damping, which IMO might help with harmonics, but kills them in terms of efficiency, which is why I'd rather design the enclosure properly from the start!

[@geddylee501]

Used to have a pair of TDL Studio 0.5's, worked brilliantly in a medium sized room, I'm all for them

[@Oystein87]

In short: Passive radiator and bass port is basicly the same prinsiple in a different wrapping that can bring slightly different results. And the air in a bassport actually comes into phase in the freq range it is designed for regardless if it is transmission or not. There is a fun video about it but don't remember the channel.

[@wilcalint]

"In short" All speakers have a natural resonance point. Lets say 45hz. How do, or do not, passive radiators or bass ports help control, or not, that natural resonance?

[@Oystein87]

@@wilcalint Tuning

[@wilcalint]

@@Oystein87 "Tuning" and at what frequency are you "tuning" for?

[@wilcalint]

@@Oystein87 This is a VERY fun subject as it really has to do with all the ways a speaker cabinet controls the resonance, at Q, of a speaker, or not. Ask a speaker sales man what the speaker port is for. You'll get a 1000 different answers.

[@Oystein87]

@@wilcalint That depends of the goal you want to achieve. And is it a sub or a floorspeaker etc. I know all this.. 1000 different answers? Not if it is a real speaker salesman.. A salesman that knows his job even only at the most basic level knows what the bassport is for.

[@joelowens5211]

We used to build transmission lines for sub boxes in car audio. Made right the bass can be incredible. It can throw off lots of volume and air with deep notes but also takes awhile to build and takes up a lot of space. It doesn't typically have great separation with quick punch bass notes like a sealed enclosure. So you would need to look at space for your room and what kind of music you mostly listen to and the kind of sound you are trying to achieve. There was a professor at GA Tech ( Dr. Leach ) who students swore by building his speaker cabinets. If you Google you can find the old info if interested in building your own box. The loudspeaker design cookbook is an oldie but a goodie also to read.

[@f430ferrari5]

Nice but with cheap wattage power and small size of Class D amps pretty sure sealed boxes are dominating now. It’s all about SPL and moving hair and even organs these days in car audio. 😂 I’ve given up on car audio since my car got broken into in the early 90’s. It’s not worth it. In the old days there used to be wattage class and it was much different. I think it was something as follows: 1-25 26-75 75-150 151-250 251-500 501 and up Many used to have a Rockford Fosgate Punch 150 for SPL. I believe the starting wattage class of today is 500w? 🤣. Insane. Sound quality isn’t great either. All about loudness. Sound quality in car audio seems to have lost its way. My experience with building woofer boxes is that sealed enclosure was the least headache. Any friends that took the time to build ported and even like 4th order or 6th order never sounded good to me or the sealed still sounded better. Back to home audio, I don’t see these transmission lines as worth it. Too expensive and too much hours put into internal cabinet design. All my home speakers have ports. Subwoofer is push pull design M&K Miller & Kreisel. I just say wow. The experts know what they are doing. I also believe quality power amps are a must. They make many speakers sound great.

[@myronhelton4441]

@@f430ferrari5 is way too expensive. How can a transmission line speaker that sounds better be too expensine if it will last a lifetime? LOL!

[@mahabkhatib9377]

Happy New Year Paul!

[@budgetaudiophilelife-long5461]

THANKS FOR EXPLAINING THIS…PAUL 🤗💚💚💚

[@wilcalint]

He didn't, but it sounded great didn't it?

[@davewin1792]

@@wilcalint He put it in layman terms. Enlighten us Bill with your knowledge.

[@juststuff5216]

@@wilcalint Well, he addressed the phase issues the BR has, and how TL's get around that. But I've been building t-lines since 1991, and I hear a lot of misnome's around t-lines. I put a few designs up on my channel

[@JohnOBryan]

I miss seeing the IRSV's :(

[@Hammersmash3dFace]

I've build a Zyklop-Sub 2 from HobbyHifi Magazine. Transmissionline with intern Helmholzabsorber and Aluminium Chassi. It was much fun to build and looks amazing inside.

[@mnfv77]

Thanks for all your knowledge Paul

[@jamesstanley7263]

I mean, there’s a bit of a difference between a Bose transmission line and my old PMC Fact 12’s

[@Phloored]

Yes, id say so!

[@steenstube]

The phase cancellation below the tuning frequency is the same for a port and s passive radiator, BUT the passive radiator has much lower Q which makes the puls response better (but also reduce the output) And you can tuve the passive radiators Q by designing the surround properly.

[@wishusknight3009]

Mass of the PR will also have an impact on performance. Not only that, but where that mass is placed too.

[@steenstube]

@@wishusknight3009 Yes, the mass and the compliance of the surroung and the cabinet volume determines the resonance frequency, as I recall the calculation

[@warpspeed9877]

Actually a properly built TL speaker gets much more and much better quality bass from either ported or with passive radiator designs. It just gets too big and heavy and is fairly difficult to construct and tune. It's made this way so as all the rear sound radiation emanating from the woofer is directed through a tuned long tube that projects in the room the ultra low frequencies in phase with the sound wave that is coming from the front of the woofer. This way you get less coloration and low bass that is fast and articulated. I get 20 Hz in room from a single 10" woofer or 16Hz from a 12" woofer...without any digital manipulation.

[@wilcalint]

How do TL loudspeakers control the natural resonance of the speaker? Nor not?

[@warpspeed9877]

@@wilcalint two ways: careful selection of tube length with regards to the woofer's fs and appropriate stuffing of the tube with sound absorbing/velocity reducing material.

[@wilcalint]

@@warpspeed9877 Agreed, but, what is all of that do? What speaker parameters are being controlled by the "tube", "passive radiator", transmission line length? BTW, IMO PS Audio speaker designer "Chris" is very very smart using those custom designed passive radiators in the FR30.

[@wilcalint]

@@warpspeed9877 Lemme explain this as best I can as it was explained to me. Take a lets say 4lb weight. Attach a spring to the weight and pick up the other end of the spring with your right hand. Now move your hand up and down with the weight suspended off the ground. Modify the spring ( tube, transmission line, port ) such that when you move your hand up and down the weight does not move ( resonate ).

[@BoredSilly666]

PMC and Kerr Acoustics are the Kings of Transmission Line. Your viewers should read all about the them as that was a very poor description of how they work. You missed half the details out and didnt even explain how it uses the Backwave pressure. I see a lot of DIY comments , it takes decades of learning the fine tuning of the inner cabinet absorption at different points to make this successful and no doubt half the DIY'ers will not achieve this. Done properly they blow PS Audio speakers out the water.

[@wilcalint]

All loudspeakers resonate. And almost always at one specific frequency. Lets say an 8in "woofer" resonates the most at 65Hz. And how efficient it resonates, power in vs acoustic energy out, lets call that "Q". So a big output peak at 65Hz. How do you control, or smooth that out, and make its acoustic output flatter? How does a vented, non-vented, bass reflex, transmission-line, passive radiator or whatever enclosures do that? Or don't they? Get out your slide rule and start here. Thiele/Small parameters: en.wikipedia.org/wiki/Thiele/Small_parameters

[@jasonme3557]

that was a great question and your answer did clear up some of my own.

[@michelcouture7026]

First time I have a good explanation! Tanks

[@jaakimheinola8705]

Hi Paul! Love to watch your video's again. Me being a DIY speaker builder, it is so exciting and challenging way to build a pair of speakers that it is something to do. So I have my own TL project on the way and it has been a great journey so far. BTW there is couple of fancy modeling softwares available to predict the performance of TL. I am very curious to see and hear how they will come to life in the end of the day.

[@ryanschipp8513]

Paul..here ya go, Sound is a sensation created in the human brain in response to sensory inputs from the inner ear. The speed of sound through the atmosphere is a constant that depends on the daily temperature. On a standard day at sea level static conditions, the speed of sound is about 760 mph, or 1100 feet/second

[@dap777754]

That sounds right to me. Not sure what Paul was thinking, or trying to express.

[@ryanschipp8513]

Paul, you should have left this one for Chris. You struggled mightily. I own sealed, traditional port, and transmission line...yes, all three. All sound great. So no, when you say bass radiator is " a better way to do it", that's not necessarily true. It's how its engineered and implemented. Not sure if anyone has told you...but when you do these videos and act as if everything PS Audio does is "better" it makes your company look bad. It's just too much of it that you do. There is so much competition out there now in Hifi. You are better off toning it down a bit.

[@Coneman3]

Simple solution: choose best options then no conflict of interest.

[@Hondaguru1122]

I love Pats 90’s-early 2000’s Meadowlark Audio loudspeakers. All were transmission line/first order crossovers. Amazing work for the price and times.

[@ronniefranks4351]

I have a pair of the original Kestrels. A lot of speaker for the money and quite nice woodworking and finishing.

[@Hondaguru1122]

@@ronniefranks4351 I do also! Still original everything. Luckily, I got a brand new matching pair in the original boxes a few years ago. The woofers are easily replaceable with a VIFA/Scan speak/PEERLESS. The tweeter is the issue

[@ronniefranks4351]

@@Hondaguru1122 Luckily, mine are still perfect. Hope they stay that way.

[@wilcalint]

All loudspeakers resonate at a specific frequency ( ie 65hz ). They are most efficient at putting acoustic energy into a space at that resonate frequency. So if you tunnel the back output waves of a speaker into a transmission line cabinet such that the acoustic waves off the back of the speaker would come down the transmission line, flip their phase, and then out into the room wouldn't that just make the speaker even more louder, even more efficient and less flat, at the speakers resonate frequency?

[@BoredSilly666]

PMC speakers are used in some of the best studios in the world and been used to produce 100's of best selling albums. PMC BB6 XBD-A or PMC QB-1 A for example. They will blow your PS Audio speakers out the water. That was a very poor description of a Transmission Line missing out half the technical reasons why they are so good.

[@Coneman3]

TL probably less common because they take a lot of making.

[@joedeegan3870]

I was a Fried dealer. I think I carried the A2 which was not a Transmission line but was a good speaker.

[@ultum4tegunz]

What fancy speakers is he standing next too ? Those must cost a fortune 🔮..😂 2:37

[@atcaleb]

Happy New Year PS family! Sound travels about a 1/4 mile a second, not 1 foot a second. I'm sure the internet would give exact distance at given temp and humidity and height above sea level. I can't remember for sure but in water the speed is either much faster or slower but its been too long since I studied these things... but I do remember 1/4 mile per second in air.

[@tactileslut]

For fun: at what frequency is the sound wave one foot away from the driver exactly in phase with it?

[@atcaleb]

@@tactileslut ask Google what frequency has a 1 foot wavelength. I haven't a clue. Speed of sound doesn't change with frequency.

[@dap777754]

Believe sound in water travels faster.

[@gtrguyinaz]

I owned infinity WTLC… speakers… they were great in 1975…. They has 360 degrees Walsh tweeter…

[@tommygun5vsrocky]

Steve Eberbach owner and designer of DCM speakers From (1974-1999) alsol worked for NASA super smart guy he really understood Transmission speakers he made a modified Transmission line speaker which took up less space then the original design of Transmission line. In the 90's he had the famous DCM Time Window Sevens which he called Rear Port Hybrid Cambered Transmission line and I own DCM Time Frame TFv10.0's which are the Modified Transmission line Steve called them. Later unfortunately in end of the 90's he sold the company to Mitek know for brand MTX they did make a nice DCM speaker trying to bring the old DCM transmission line back but not all the same DCM design those which did not help. The speaker for the new company was DCM TFE200 which i own as well great speaker for the price that used transmission line but Mitek did not do much with DCM and sold it again now its really dead and not a audio product company anymore. Pretty sad its like Thiel Audio just sold and killed off the company to nothing. I am so glad PS audio made it over time. Oh side note DCM tw7 and TFv10.0 go down to 20hz on the TFv 10in woofer with transmission line and 25hz on the Tw7 9in with transmission line.

[@frankkniseley9951]

I still have my DCM TF 600s I bought new in 92...they still sound great

[@Alvedrotten]

One foot per second 😂

[@mikecampbell5856]

I learned something today. Thanks!

[@wilcalint]

Ya think so, or was it all BS

[@paulredding5347]

Didn't learn about the speed of sound.

[@wilcalint]

In a Transmission Line Cabinet design what determines the length of the transmission line? Is the end of the transmission line ported, or not?

[@crackyflipside]

The end of the line is usually ported to the front, but you can also leave the line sealed to behave like a sealed box to eliminate air spring effect. For rough starting point you get the speed of sound (343m/s) divided by resonant frequency of the driver, then take that number and divide by 4 to find the quarter-wavelength. Then you play with the length, position of the driver on the line, cross-section area of the line, and stuffing until you get a good looking frequency response using something like HornResp to model the response.

[@harleyn3089]

You said "sound travels about 1 foot per second". It's actually 1 foot per millisecond, or 1000 feet per second, depending on altitude and air pressure.

[@Paulmcgowanpsaudio]

Yup. Few decimal points off there! Thanks. Duh. I foot per second is crazy talk!

[@Reflectiveness]

The natives are growing restless. 😜

[@davidfromamerica1871]

It’s all a snake oil salesman con to get you to part with your money to the tune of tens of thousands of dollars, often hundreds of thousands of dollars. The snake oil salesmen con is you cannot fill a room in a house with music unless you spend a astonishing amount of money. People with more money than common sense buy into this snake oil sales business as long as they can keep finding gullible people.

[@madds6678]

You don’t see many transmission line speakers these days ? I think PMC & Spendor may beg to differ

[@boshaznip]

Good explanation, but not quite entirely correct. Ported loudspeakers have the sounds coming out of the port in phase with the driver within its correct operating range. The combination of the box volume and port diameter and duct length form a resonant cavity that works as a Helmholtz resonator, centered around the tuning frequency. It works much the same way as blowing across the top of a bottle and when you get it right, it will resonate. If you change the amount of liquid in the bottle, it changes the pitch. When the driver excites the air inside the box at the tuning frequency, this resonance causes the air mass within the port to act as a spring of sorts, such that it inverts the phase so that as it emanates from the port, it is in phase with the driver. As the driver cone moves out, the air is moving out of the port. This causes a reduction of pressure inside the box, and once the the reduction in pressure overcomes the inertia of the air flowing out of the port, the airflow within the port now begins moving back into the box, while at the same time the cone of the driver starts to move back in towards the box. This causes a spike in internal pressure, and the reverse happens and the cycle continues. This is why at the tuning frequency of a ported speaker, the cone movement will actually be much less than in a sealed box, as it has much greater acoustic load applied to it, which is why drivers suitable for ported boxes need much stronger motor assemblies, and this is how they can generate more bass. Once you go below the tuning frequency of the port, then the air movement becomes out of phase with the driver, and it becomes unloaded. This is when it flaps around and moves uncontrolled because it has lost the damping force from the cabinet. The passive radiators behave in the exact same way as a port, except instead they are a sealed diaphragm and the mass and compliance of the moving components take the place of the air mass within the port duct. The passive radiator still has a tuning frequency, and if going too far below that will still unload the main driver, however to less of a degree as the mechanical resistance of the radiators suspension will stay fixed and still give some resistance. Also, another benefit of the passive radiators is because it is sealed, you don't get any air chuffing noises caused by turbulence commonly associated with port tubes, which is made worse from hard 90 degree corners or sharp edges. Transmission lines, as Paul mentioned, are also a way to allow the rear wave of the driver to exit in phase with the front of the driver. The main difference is that ported cabinets and passive radiators are reactive tuned systems centered around a tuning frequency, whereas T-lines are simply a form of mechanical delay, typically set to 1/4 of the wavelength of the drivers natural resonant frequency. The ideal cross sectional area for a T-line is equal to the radiating area of the cone. And by not being a reactive tuned mass, the driver doesn't get any substantial acoustic loading from the T-line, so can move much more naturally and giving a more faithful reproduction of the input signal and the exiting wave has less distortion as it is not the result of a resonant tuning with greater pressures. As mentioned, the biggest reason T-lines are not commonly used is the physical size that they can occupy when designed and built well, plus the additional cost involved, but they can be exceptionally good performers when done correctly.

[@n.lyndley.9889]

Someone who actually knows what they’re talking about, and not just spouting a misinformed opinion. Thank you.

[@gotham61]

@4.14 “sound travels at 1ft per second” HUH???

[@RoderikvanReekum]

B&W Dm 2a Amazing bass for a small woofer but a bit to much around 40Hz.

[@ThinkingBetter]

Ideally the sound waves follow the signal and the bass stops and starts as quickly as the signal. That’s the idea behind the servo subwoofer in a sealed box. It’s sad that few companies master this much more challenging bass perfection technology.

[@DanielJackson-f4t]

I own a pair of transmission line Meadowlark Heron Hot Rods, first generation, and will never sell them. Bass clarity and extension is most impressive.

[@ahnenpost5237]

Needs to be added: first transmissonlines ever constructed used not the described principle. The principle then was to cancel out all the sound, that was radiated into the box while not affecting the resonance frequency of the speaker, that only rises a little bit with this type while a lot more in closed or vented, because the compliance of the enclosed air-volume adds to the one inherent one in the drivers suspension. Result is more bass in the lowest range right above the significant lower resonance frequency compared to vented or closed enclosure. Today`s transmissionlines do not get the back fired sound perfectly into phase, there is still phase shift of about a quarter wavelength adding to the direct radiated soundpressure, but smearing the pulse because of beeing off phase a bit. The intention today is alike the intention of vented enclosures: use a resonance to first delay the sound propagation such that the outcomimg sound adds to the one fired to the front (90 degrees off in in both) and second to use the resonance to even enhance the strength of the "reflected" (e.g. inward radiated soundenergy) at this decent resonance frequency "filling" the hole right above the drivers resonance frequency. The advantage is a significant gain at the low end but a drawback in pulse response attack and a much greater size of the enclosure. The line furthermore introduces several higher order resonances of the line adding to the sound waht is not intended and is hard (impossible) to prevent.

[@davidshepherd728]

4:10: "sound travels at about 1 foot per second"!

[@ubza1234]

Lol ports are only out of phase below the tuned frequency of the port. At the frequency, there is a 180° phase delay (not phase inversion, but the result is pretty close) and above the tuned frequency, the mass of the air is too high/heavy for the input pressure from the driver to exit directly out of the port. A combination of the air mass and the springyness of the air mean couplings is poor. A little bit of air movement does exit, but not much. I implore you to play with a slinky. Bounce out above resonance, below resonance and at resonance. Notice the directions the slinky is moving in your hands, vs the other end. Then everything makes sense, I promise you ☺ you've said ports work out of phase a few times Paul and it's not entirely true 😉 While there are many advantages of passive radiators over port, this fundamental is just as true in both. A passive radiator works exactly the same as a port, but I a different form, that is too say, in a port, the weight is the air in the port and the spring is the air in the port as well as the air in the enclosure, while with a passive radiator, the weight is the cone assembly, and the spring is the soft parts and the air inside the enclosure. The mass and rigidity of the cone assembly can filter a little extra high frequencies, but the principles of operations are the same, including the phase relationships below fs, at fs, and above fs. Transmission lines can definitely have a lot more phase issues, because unlike a port, which essentially cuts high frequencies, boosts and phase delays at resonance, and passes all frequencies below resonance, (which is our of phase to the front of the driver) a transmission line passes all frequencies (it filters a little of the highs but far less then a ported enclosure) however, the length of the transmission line is thus that by the time the sound has made it through the labyrinth, the sound is in phase with the front of the driver, but only at a single frequency. As you go above and below that frequency the combined sound wave becomes more and more out of phase. This means a wider boost in theory, but eventually there will be frequencies that don't line up at all, then you rang a harmonic that does line up, then one that doesn't, etc. That's not ideal. One of the advantages of this design is that the driver is completely unloaded, similar to an open baffle, meaning higher sensitivity and dynamics/"fastness" with the compromise of the above mentioned phase issues, enclosure size and complexity, as well as no resonance related boost at the tuned frequency of the transmission line, only the combination of the two waves which I think is around 3db from memory vs 6-9db of a port. Every design is a compromise haha

[@trutmaasfull]

It’s all about that bass, no treble…🥵🥳😱🥳

[@davidfromamerica1871]

When I am in a cheap motel. The sound of the bed headboard in the room next to me is banging up against the wall in rhythm, the girl screaming her head off. Which sounds am I hearing first. .?? I wrestled with this technical question for decades. Only a true Audiophile would know what pounding rhythm he should apply to the wall in his response. Should you pound on the wall in between the screaming and the headboard banging..?? How loud should you yell through the wall as you are pounding your fist on the wall into a bloody piece of meat..

[@edd2771]

Haven’t watched yet but prediction- Paul doesn’t make them, so he’ll say he doesn’t like them.

[@jamesstanley7263]

😂

[@PSA78]

I'm not sure why he would make something that he doesn't like. 😄

[@jvandekant]

The topic is about why he doesn’t want to make them

[@stephenstevens6573]

As predicted...he did explain the differences between the basic types of bass management, but of course insists that the design that they use is superior. Only thing is, by his very explanation he kind of tells on himself by explaining the complexity of the cabinet design in a transmission line speaker. Comes down to the expense of doing that. Boils down to the fact that the manufacturer cannot pass along that extra expense on direct competition with the design that they use. He says superior, I'm guessing that it's more a case of less lucrative (no hate. That's what he's in business for)

[@edd2771]

@@jvandekant No, the topic is the following question: What makes transmission line speakers unique and rarely used? Paul comes close to saying if cost were no object they would be the best way to port a speaker, but then defaults to a passive radiator being better for reasons unexplained (except for the astounding coincidence that the FR 30 uses them). It would be nice, but admittedly surprising (given the man is an audio salesman of his own designs), to be just a bit more transparent. But he did the same not quite honest thing with open baffle speakers recently, and has done so with various circuitry architectures in the past, hence my (accurate) prediction. Good day.

[@martinjandijkstra3205]

There are more unique features. Important one is lack of compression compared to a small bassreflex tube.

[@ford1546]

doesn't a sport work as a push pull system where 2 speakers are mounted together front to front but one speaker is a bass port???? with a bass port, you will ALWAYS get air noise!

[@Curi0u50ne]

…I would think it is used a lot today especially in the do it yourself scene who are achieving a build that shops would charge an arm and a leg for…..for a fraction of that price and the self satisfaction of achievement 😅

[@wilcalint]

The best transmission line subwoofer I ever heard was called "The Coffin". That due to the fact that it was about the same dimensions of a coffin. It had a pair of 8in KEF oval drivers in it. Anyone remember that?

[@stevesmyth4982]

I built The Coffin from 1" thick MDF and used two of the updated KEF B139 drivers (150 Watt, longer excursion) and filled it with 20 pounds of long fibre sheep's wool. It sits in a bay window behind four pairs of vertically stacked Quad ESL 57s that hang on chains attached to the ceiling, it sounds great but my lady friend said it's unaesthetic.

[@wilcalint]

@stevesmyth4982 That's why it was nicked named "The Coffin". Super deep bass.

[@larrycooper7249]

1 foot per second...What!!!!!!!!!!!!!!!!!!!!!

[@D800Lover]

_"Sound travels around one foot per second."_ Ahem... I refrain from correcting that... leave that to others... [Edit: 1087 feet/second]

[@amail1111]

Obviously Paul doesn't know that much about various bass loadings/ports, etc. but hopefully he knows more about making money.

[@Pentenfi]

Hmm I wonder why he appears to know so little about the physics of loudspeakers. I mean, bassreflex is a Helmholtz resonator and the physicsis is not that complicated. Getting into the details, yes, but for a rough understanding...

[@Coneman3]

As usual money demands simplicity more than SQ.

[@geoff37s38]

“Sound travels 1 foot per second”. So if someone speaks to you across a room 15 feet away we hear their voice delayed 15 seconds after their mouth starts moving? Hilarious. Paul ain’t no engineer.

[@mahabkhatib9377]

1087 ft / sec

[@richardsmith2721]

Only in Japan. I have seen several movies like that where the voices don't match the mouth.

[@AmazonasBiotop]

He clearly misspoke. But the speed of sound is impacted by temperature and air pressure. So maybe it is very cold and with very low air pressure there Paul are.. 🤣🥰

[@richardsmith2721]

I'm no engineer, but maybe he was referring to bass frequencies?

[@wilcalint]

Pauls explanation was totally in outer space. But it sounded great didn't it?

[@TherealBobFaith]

one foot per second bass w/ 2 subs biwired onto the front loudspeaker. need 3 more subs

[@florianhofmann7553]

nah just get proper big speakers with 15 or 18 inch woofers and drive them with a class A amp. My REL sub doesn´t hold a candle against that.

[@crossoverchef]

short answer = because they are too big.

[@gtric1466]

Speaker upside down

[@Justin-fy7xk]

Ports fart too much. Passive radiator is the way to go.

[@robertmitchell6015]

Well explained

[@ryanschipp8513]

Are you serious?

[@robertmitchell6015]

Sarcasm