Why aren't rotary subs more popular?

[@robertharker]

I attended a demonstration of a rotary sub at the 2008 AES conference in San Francisco. It was amazing. The fan is about 2 feet across. It was mounted in the doorway between to adjoining hotel rooms using the second room as a compression chamber. One benefit of rotary sub-woofers is that they have very tight, punchy low bass. The fan can grab a lot of air and shake it with very little distortion. A complete unit is about a cubic yard and can replace tens of sub-woofers. High pressure subsonic waves below 10 Hz are very disorienting. I found they induced mild virtigo. It was fun watching the CD cases migrate across the coffee table. The inventor said it was very hard finding recordings that had any meaningful signal below 10 Hz. Mostly movie sound effects. The other big problem is that it is very difficult to contain high pressure infrasonic sound. I could hear the fan from the other end of the hotel floor. I walked down the stairs and out on to different floors. I could hear it clearly one floor down. I could still hear it two floors down. I recall three floors down it finally started blending into the background noise. I suspect that movie theaters don't want the infrasonic sound of one screen to be heard in theaters two or three screens away. BTW, my personal experience is that infrasonics have to be loud to be heard (experienced). Low volumes just become part of air pressure changes that surround us every day. That is my experience, YMMV.

[@betaomega04]

I imagine a great deal of pipe organ music can go down to ~4 Hz

[@smatchimo55]

very cool. I read a similar comment somewhere else while going down the rotary rabbit hole, regarding very little content being recorded at low frequencies. One being the cannon shots in the classical song I forget the name of, some kind of overature, and various enthusiast recordings of rockets lifting off, trains going by, etc. All of which are pretty fun to demo, imo, but that's about it. Also your comment makes me realize why I so often have to adjust my car audio from track to track due to some bad tuning and choice in box by me. Trying to get down to 30hz with a little 10" in a 4 door sedan was probably a bad idea, and 60-80hz reminds me of it every day. unfortunately my door panels can't take much more than 90hz without buzzing, so low passing >60hz isnt possible.

[@HansDelbruck53]

It's vertigo (see Alfred Hitchcock).

[@bassfan71]

That's so cool. Pipe organ music would shake the hotel to the ground if he played that. I very much would like to experience listening to a rotary sub one day.

[@Athleticblacklesbian]

@@smatchimo55 2 jl 8w7s in a custom built ported 3cu foot enclosure on a jl 500/1 wpuld have given you everything you wanted. A single 13w7 on that same amp would bring the lows you want.

[@jeffbarton3353]

I heard Mazda stopped producing them because of reliability and emissions problems........oh wait

[@CullenDelmore]

Oh, how I miss adding oil when filling up at the gas station. And clearing floods in the cold.

[@jeffbarton3353]

Cullen Delmore lol mine never flooded by i do miss the whirring jet-like motor noise and the removable sunroof. Good times

[@BruceRichardsonMusic]

Hahaha. I miss mine, too. I got lucky, mine was not a problem with oil. But what I miss most is the way it cornered and had that nice balanced drift when you were pushing it to the limit. I really loved driving that car.

[@jeffbarton3353]

Bruce Richardson yep mine was an early 80s model so no power steering made it race car like in corners

[@InsideOfMyOwnMind]

I miss having the throttle stick in 1st gear and seeing the tach bury at 10+ quicker than you can blink before you shut the key off and hydrolock the motor with all that fuel on the spin down. Yes, my tach literally pointed straight south.

[@kermitthehuman]

I used to attend electronic music shows at a concert venue with a single TRW-17 rotary subwoofer. That place would take your breath away when the bass hit. Years later, another venue was structurally reinforced, and had 3 of those same systems installed. When the bass hit, a friend and I had to hang onto the stair rails, so we didn't fall down. If the outside door to the smoking area opened, then the bass would knock cigarettes right out of people's hands/mouths. Truly feeling sub bass is a whole different animal than hearing notes within our range 😁

[@user-qo7qt3wq7h]

Yo wtf you can stay more than 20mn or everyone was begging to lower the power ?

[@kermitthehuman]

@user-qo7qt3wq7h The older people did lol. The young kids absolutely loved it. I haven't been to that venue in a while, but I heard that their sound guy keeps it a bit more tame most of the time nowadays 🤷

[@gregmorris2022]

There is a fan in the ceiling of my bathroom. I've been known to "pressurize" the air in there. My wife, however, routinely fails to appreciate the musicality of these pressure waves.

[@InsideOfMyOwnMind]

I have a recording of a dinosaur belching from a Jurassic Park clip. This is a really loud wet guttural belch as you can imagine. Sometimes I play it at my work station after lunch and say "pardon me."

[@flowgangsemaudamartoz7062]

@@InsideOfMyOwnMind :D

[@biketech60]

Mine is a recirculating fan that does nothing , but it satisfied the apartment building inspectors .

[@paulstubbs7678]

Is that a 'brown' note?

[@cjpaul8571]

I met Bruce Thigpen at Rocky Mountain Audio Fest and heard his rotary subwoofer. What he did for the demo was install a temporary baffle in the passthrough door between two rooms, creating an infinite baffle. It was an amazing experience. My friend who was present for the demo had to leave the room because the ultra low frequency made him queasy.

[@MikeDS49]

Subsonics is one explanation for the belief that people can get that an area is haunted. They can't hear it, but can feel it which can cause an uneasy feeling.

[@supremebeme]

just watched some polish kid create his own rotary sub woofer and now i'm here

[@the_mister_magister]

u aint the only one

[@drummerdoingstuff5020]

I too

[@chezlunati2494]

Me also

[@CaptainMurphy627]

Same lol

[@randybehill8136]

Word...

[@rakitakhan]

Most places that have rotary subs installed first have to be inspected by a structural engineer to see if the building and foundation can handle it. If you have double or triple paned windows in your house, prepare to have the seals blown. So, they can literally have your home falling apart if not installed correctly. I'll have to be happy with my Delcoid and Monoilith subs.

[@chrisvinicombe9947]

This is fascinating I've never heard of these before.

[@tims244]

You should also check into plasma speakers

[@BASSstarlet]

i've read about "Cyclone" for automotive use back in the 90's.

[@greenpogo]

Yup me either - and I used to design speaker systems.

[@MatthijsvanDuin]

The cyclone is not a rotary woofer. It uses a motor to wave a panel back and forth, which is essentially the same as a normal speaker, even if their design is rather unusual.

[@BASSstarlet]

The "Cyclone" whom refer to was like a giant fan.

[@iismitch55]

I actually made one of these based off the design of the guy in the channel you got that picture from. It’s quite an intricate piece. It still works without a box. It’s less efficient, but it works. I wasn’t able to run it properly above 20 hz, because the forces involved will cause it to shake itself apart. That’s also why thigpen’s design includes a very expensive dampening system. I don’t remember exactly what I paid, but I bought parts new since I was following a design rather than going from scratch. I ended up with maybe $600 in it, and the base was fabricated for free.

[@iismitch55]

Here is the channel of the guy who helped me. Super nice chap! kzbin.info/door/rmcuIn2bTUXOoJ1ObODwEA

[@jeffclark5024]

I would really love to experience one. I find them fascinating however the cost, the space requirements and the fact it could literally shake my house apart is keeping me on the sidelines

[@robertromero8692]

I did experience it, at a hifi show. It was fascinating. Immense infrasonic power.

[@jeanmichaud1151]

Hi Paul, my name is Jean Michaud I'm from Québec, Canada. I love sounds systems for many years. I got my first stereo at the age of 10 and now I'm over 50. I realy love your videos, l learn a lot. I like the way you do your videos, a mix of technic, fun stories and respect. Keep the good work! 👍👍👍

[@gotham61]

Bruce and his company Eminent Technology are very much still around! In addition to the TRW 17 rotary woofer, he still makes the ET 2.5 linear air bearing tonearm, and his LFT speakers, which are planar magnetic not electrostatic.

[@RyanStone143]

I love both my sets of lft-III and original lft-8a!

[@snap-off5383]

Who are their customers?

[@snap-off5383]

Found it: The TRW-17 rotary woofer is now being used in theme park attractions, concert venues, professional audio applications and research projects.

[@imdbtruth]

This old guy is a legend 🙌

[@Acoustic_Theory]

Before watching the video, here are my impressions. I'm aware of four types of rotary subwoofer - subwoofers that convert rotary motion to air motion. The first is the Phoenix Gold Cyclone, where a rotating vane is coupled on either side to a curved waveguide that redirects the airflow forward and backward. The second is the Bruce Thigpen Rotary Woofer, which is like a fan where the blade pitch is adjusted by a voice coil motor. The third is the Servodrive method used in the Contrabass, BassTech 7, and SDL5, where a rotary servomotor is coupled through a rotary-to-linear motion converter using belts to a pair of opposing cone diaphragms. The last is the Intersonics Servo-Valve loudspeaker used in the Sonic Boom Generator, where an airflow source is coupled to a pair of output openings operating in opposite acoustic polarity through a valve where a rotating vane is driven by a servomotor. The one approach above that doesn't involve Tom Danley is the Thigpen Rotary Woofer by Eminent Technology. All the rotary woofers involving a servomotor driving a vane must rotate back and forth, so they have to fight the rotational inertia of the vane, and as a result they have limited upper frequency. The servomotor in the rotary-to-linear systems must also rotate multiple times to go through the full range of excursion (which is still mechanically limited by packaging and suspension geometry), so there is a lot of rotary inertia in the armature of the servomotor itself. Linear motor systems have similar inertia which must be overcome at high frequencies to avoid a decrease in amplitude as frequency increases. The Bruce Thigpen Rotary Woofer, being a fan, doesn't have to stop rotating and rotate in the other direction (AC rotation) - the rotation is continuous, enabling the fan to produce a "DC" air current. Its problem is its bladepass frequency, which comes from having five blades rotating at some speed. An acoustic lowpass filter is needed to absorb the bladepass frequency, and this is actually helped by having the motor spin as quickly as possible, but the motor is an AC induction motor which are commonly available in 1700-ish RPM (4 pole) and 3400-ish RPM (2 pole) variants, and higher speeds than that can't be achieved without increasing the line frequency from 60 Hz to some other value using an inverter drive. Multiply that by 5 and then divide by the number of seconds in a minute, and you have the bladepass frequency. If the bladepass frequency can be maximized, it can be effectively filtered by a smaller acoustic filter, but the size of the acoustic filter needs to be large to be effective at the bladepass frequency, and it will necessarily have a low corner frequency that also limits its upper frequency bandwidth. The advantage of moving-coil, linear-motion speakers is their very low mass, thanks to the columnar rigidity that comes from being comprised of shapes that are revolved around a central axis (the cone, voice coil former, surround, and spider), so they can have a very wide effective bandwidth, and they are not prohibitive in cost. If you think of acoustic systems as having a gain-bandwidth product (similar to ICs), you can also use acoustic filters that narrow bandwidth of your cone type drivers in order to obtain resonant gain, at the expense of bandwidth and rise time, and horn loading can be used to combine bandwidth reduction and acoustic impedance transformation to greatly increase system gain. For now, the dynamic driver with linear, permanent-magnet motor has the edge in simplicity and low cost, even when subsonic output (below the range of hearing) is necessary.

[@rotaryskratch18]

That's fascinating, I'd love to learn more. I'm an aspiring inventor, I came up with what became Serato and Traktor almost 20 years ago. Also incepted a new type of variable lift, timing, and duration camshaft and control system that I'm trying to see through to fruition, as well as other ideas. At this point I don't care about money, I just want to get a viable idea into production. Good day to you sir (3 years late).

[@Sharkie1717]

@@rotaryskratch18 I hope all goes well!

[@organicvids]

Couple a cyclone with a jbl gti comp sub and ur in heaven. Put on opposing sides of room.

[@kumoyuki]

ofc, a 10HZ horn tends to be large

[@macrotech6507]

Fantastic video. Tom Danley makes a lot of unbelievable sub bass systems(live sound) They made a subwoofer out of a shipping container called the matterhorn and they show it being built on youtube. This thing can actually modulate a mountain and be used for non explosive avalanche control. I have 2 of their TH118(tapped horn design) subs and they will choke you they hit so hard with a bass drum kik. Super efficient too. These guys are scary smart.

[@KevinWorrell]

I have a pair of TH118's as well but they don't compare at all to the TH812 which I have two of as well. The TH812 is the most musical sub I've heard of Tom Danleys. The TH812 like a lot of power, am driving them with 12k watts ea.

[@macrotech6507]

@@KevinWorrell I've seen the specs from their website. For fk sake you need a 3 phase power supply for them! LOL LOL

[@KevinWorrell]

@@macrotech6507 I run the amplifiers on a 30A 240v circuit.

[@neilw4569]

Servodrive Basstech 7, It hit over 150db,loudest sun ever.

[@macrotech6507]

@@neilw4569 I've hear/felt them. They are ridiculous!!

[@521wurlitzer]

That would be great in organ applications where there wasn't room for 32' pitch (about 16 Hz) organ pipes. Or in the case recording reproduction of the Atlantic City Convention Hall organ 64' pitch.

[@N4CR]

You can do it with very high excursion 21" and larger subs in 1-2m2 sealed enclosures. Or maaaybe a custom sub with a port. Others i've seen make giant horns. But rotary would be unbeatable..

[@drubradley8821]

Some 20 years ago, at my stereo shop, one of my product lines "Phoenix Gold" offered in pre-ordereded limited production supply, the "Typhoon", which is some what a rotary sub woofer, but was more of a reciprocal action rotor subwoofer that from the relaxed or natural or static point of the paddles or the "would be" cone, was for sure a radical thing to see, let alone, I thought it would be a good idea to have 4 of them installed in a Chevy Suburban demo display.... Ummmm, only one was actually needed, as 4 of them at full throttle, was breaking stuff on the vehicle like window glass, cash cluster, etc. How those structure of the units would not break apart themselves, I do not know. If I remember correctly, I think the maximum input power in watts, was 150 watts, with a peak of 300 watts? Running the processing active cross-overs to limit how much band width was allowed to go into them was a key factor, as if too much of too wide of a frequency spectrum they would get pretty muddy, or to say, they would get out of control and distort, but maybe a couple 5 to 10 bands worth of low frequencies for running full power, was required. At listening levels for music, you could widen the band widths from approx 5 to 300 and they would perform wonderfully, again, only at listening levels though, maybe at a yelling level, just not full wide open throttle, lol Those units had to have a compression type loading like the hatch back of an automobile, or in the corner of a room. If being run in home audio, you then needed to reduce the gain to the very lowest, as they offered a very boomy output, but, if the units were for sound quality, and to just face them towards you, in a room, as one would do with standard cone woofers, you would hear the whisping sound of the air bleeding past the paddels at lower volumes, so aiming them away from the focal point mattered, or should be indirectly mounted. Which brings up having one in my home, DON'T DO IT!!!!! ,lol... Very hard to match to the rest of the speakers output. they seem to not have the same acoustical output rise that a standard cone woofers has. Very over bearing even at lower volumes. Granted, you you are constantly rocking the house at full throttle, then yes, by all means, you are covered with one of these TYPHOONS, which were approx size to 12 inch diameter woofer, and could slide right in, if the enclosed was the correct volume for the Typoon. Now, a down side to those units, I heard stories of them being installed in the wrong sized encloseure, and they then would tear them selves apart. that never happened to me, as I didn't want to spend $800 a piece on new units, lol. they do require a large enclosure, if my memory serves me correctly. I made a coffee table that was the woofers enclosure, that didn't work, as it was just too much boom, with a massive wave length. Allow me to example, watching a movie one night, and the volume was what you would hear and feel at your typical theater, we noticed red and blue and white flashing lights through the window blinds, only to realize, our beloved police were actually standing at out front porch, banging like neck on the door, lol.... Oops!!! It was a noise complaint from my neighbors, ALL OF THEM.... and my closest neighbor lived approx a wee bit further then a half mile away or 3800 feet away. their complaint was not just the sound, but, stuff was vibrating on their shelves, lol.... I felt all bad, as I was just excited about giving the coffee table a test run, and never put any thought into the wave length that these units can achieve. I hope that none of these gets confused with the idea that these Typhoon units have a high acoustical loudness, as they are not any better or worse, rather, that the ability to control any speaker, accurately, and give the speaker clean stable power, I suppose is the idea... Please feel free to correct me... As my info is 20 years old, and have been retired from that industry for about 18 years now... Thank you for the video, I enjoyed remembering some old stories that I had forgotten about... Dru

[@Inkreptile]

Wow awesome stories! Really makes you appreciate how low and powerful these can get

[@KevinWorrell]

The Typhoon was designed by Tom Danley of danleysoundlabs when he was part of Intersonics. On my channel you can see a video of that technology in action.

[@drubradley8821]

@@KevinWorrell Right on, I shall look into that video. Thank you...

[@nickwallette6201]

The Phoenix Gold driver was called the "Cyclone." I have one, but I have never really been able to use it. They had a fairly critical engineering flaw where the magnets were essentially loose powder compacted into form, and would constantly shed particles. It would get _everywhere_ in the motor structure, which caused audible noise (often louder than the sub itself), until the entire thing eventually seized up. A couple years ago, I pulled the motor apart to see if it would still be possible to clean out the housing and maybe varnish the magnet to keep its guts intact. Then we had a particularly violent earthquake, and it fell a few feet to the ground, which cracked off a corner of the magnet. So now I have to figure out whether it's possible to epoxy(?) a magnet back together. I've had the thing since I was like 19, and it's definitely on my list of projects for "some day." If time and acts of God don't take it from me first.

[@drubradley8821]

@@nickwallette6201 Ah that is right.. the "Cyclone"... How in the heck did I get that wrong? DUHHHHH... I think it was from the GM sport SUV and sport truck names... Thank you for the correction.. I remember writing that, and had to pause for a second, and it felt weird writing "TYPHOON".. LOL.. Something was off about that name I wrote.. I feel silly now.. But, Thank you so much for taking the time to fill in the correction, not just so I don't look like a complete idiot, but, in case of others desiring to go down that rabbit hole with one of those oldie but goldie's of a speaker..

[@jstagzsr]

infinite baffle is the best way to get the best results for a rotary sub. aka put it in a window. your house is where you listen and the planet is your speaker box. i JUST watched an awesome youtube video on this subject a couple days ago. even at 1 hertz there was very noticeable air movement. even watching it in a video where you cant hear it. everything in his house was rattling and his doors were opening and closing slightly with the air movement. amazing project. I thought it was gonna be some rigged together garbage but it actually came out extremely good. i wish i could find the video to post a link so people could get a better understanding on how they work.

[@MinerMike24]

I think I just came from over there too! Here’s part 1: kzbin.info/www/bejne/hIuudKt_qq9ga68si=ogXKmPa4lY1rDXKy Absolutely wild to see, and he did it so well!

[@Yeahyeah-ic8xm]

And now he broke his house by playing 4 Hz 😂

[@JDfromWitness]

I have a couple of ContraBass ServoDrive subwoofers. Very interesting design that gets around the efficiency drop that occurs with voice coils on large cone excursion by using a low inertia DC servo motor to drive the cones. Apparently very big back in the 1980's and used by theme parks. 17-80Hz, +/-6.5dB which is pretty low. Mine came to me through a pipe organ repair and I ended up on a journey that took me back to the creator, a gentleman called Tom Danley. I was able to get them working. The reason they disappeared is the motor that was used was commonly used in large tape drive in those very old computers. Once that market died, the price of the motor skyrocketed making them unmarketable. Still, a very interesting cabinet that used two 15" pistons, and two 18" passive radiators in a "somewhat" compact cabinet. I should mention that sometimes pipe organs cheat on that last 32 foot stop due to building size limitations.

[@polygonekoma]

Recently saw a video where a dude put one up very cheap for 200 here on youtube. He basically used RC plane components to control the flaps. Go check it out

[@Graxu132]

You're talking about Daniel Fajkis just saw him before this video was recommended for me

[@polygonekoma]

YT algo does a good job. Thats how I landed here :D@@Graxu132

[@johnmarchington3146]

Thanks for explaining what a rotary sub is, Paul, because it was completely new to me. As you alluded to, I imagine the cost of setting up such a system would be enormous

[@Paulmcgowanpsaudio]

My pleasure. Thanks for watching!

[@engjds]

A guy builds on on here (YT), for about £400, because I was going to build one years ago, I still might).

[@engjds]

@@Paulmcgowanpsaudio They used these rotary subs to replicate elephant mating calls to good effect in Africa, one tried to make love to the sound van, true story.

[@SocietateaAscendenta]

YOUR VIDEOS are so Relaxing - no Graphs, no stupid Snobs snobbing about stuff and hitting you with meters and scopes.... I could go to sleep, listening tho your Videos. Thank you!

[@BillBogan]

I use tactile transducers in my couch. It gives a nice low frequency effect, cheap and easy.

[@johnclark3067]

Haven't yet but I may play around with those someday. Just vibrate what you're sitting on instead of pressurizing all the air in the room. Must be awesome for movie LFE.

[@turbojoe2]

My wife hates those! But they do add some "feeling".

[@peterzingler6221]

You do better by putting them on the floor or the walls if you have concrete walls

[@user-jh8cx4jf7u]

I do too. But I have to first eat some Taco Bell first... 💨 Only thing is it's inconsistent. 😂

[@joshpoe]

Cheapskate

[@tapemaster8252]

This is one of the best ever videos, I learned something new

[@gotham61]

I have heard the TRW17 on a couple of occasions, and it is an awesome experience. As Paul says, one problem is finding program material which goes that low, as it really doesn’t go much above 20-25hz. The installation is complex, as you have to build it between two rooms, and run it through a labyrinth to reduce the noise before it vents into the listening room.

[@HareDeLune]

gotham61 I wonder if you could use Tesla's idea of vibrating a fixed column to achieve a similar result in less space?

[@vinny142]

@@HareDeLune "Tesla's idea of vibrating a fixed column " Tesla made a claim that he could destroy a building by placing a small shaking device on it. Resonance (*not* a Tesla idea) would then cause the builkding to shake more and more violently until it fell apart. By the time Tesla made this claim he was quite mad and forgot all about dampening. The amount of energy you need to put into a building to get it to move is earth-quake level. Anything less is simply absorbed and dissipated.

[@oldfarthacks]

@@vinny142 Or we still just don't quite get what he was trying to say.

[@N4CR]

@@vinny142 'tesla was mad' lmao yeah that's why Sir William Crookes and Sir Michael Faraday highly respected him while all their scientific sellout buddies turned on Tesla? Until he disproved the current and incorrect EM theory they loved him. Strange eh!

[@turdferguson814]

@@vinny142someone has clearly not seen the Mythbusters episode where they tested the very thing you’re claiming is bunk 😉

[@TheLongjohntim]

Thank you! You just explained what I experienced after 9/11 when all the planes were grounded. The silence or the lack of sub sonic sounds created by the jets, though we may not consciously hear it, we are aware when it's no longer there. I didn't fully understand what I wasn't hearing till you talked about sub sonic sounds. Again Thank you. Perhaps you could do a video on this next year about this. It was an experience I'll never forget.

[@BenInSeattle]

Have you tried a sensory deprivation tank? I have heard they are very relaxing and I would think a large mass of water might dampen the subsonics.

[@SIedgeHammer83]

thanks for explaining rotary subs is, I don't have to google it.

[@TSC-Detroit]

Fart in a wind storm lol I'm dying here

[@MrDac0964]

Jason T 🤣🤣 i know... almost fell off my chair

[@mers5499]

Very common expression, turn off your computer and go outside.

[@InsideOfMyOwnMind]

It's not the voice coil burning that you smell.

[@kazkylheku1221]

Very common expression; I've usually heard it as "fart in a hurricane". It denotes anything that is orders of magnitude too weak to be effective in the situation.

[@james6039]

I thought that was funny also. Never heard that or a Rotory Sub before.

[@woodybob01]

It's crazy how ideas permeate the cyberspace. One video comes out on some other channel, and before you know it, there's a whole bunch of interest and new videos surrounding that idea. The modern age is truly something.

[@rcary]

That "raspberry' fart noise was about 20hz! Good job. 🤔🤔

[@mikeh2520]

Frequency Response: 1Hz : 30Hz ± 4dB Suggested Crossover: 20Hz @ 18dB/octave Sensitivity 94dB 1 watt 1 meter @10Hz Maximum Acoustic Output: >115dB between 1 and 20Hz.

[@KnowName33]

115? That's not loud at all for sub bass

[@r-phammink6492]

@@KnowName33 For 1 to 20Hz it is...

[@jimthvac100]

This is the best explanation of a rotary sub I have heard yet thanks!

[@LarsonChristopher]

Phoenix Gold used to build their Cyclone rotary car subwoofers. Thanks Paul

[@mephInc]

And they sucked. lol

[@simonlinser8286]

i learn something new every day on this channel, even if it was 4 years ago.

[@der_pinguin44]

I remember back in 2006 seeing something like this on hackaday.

[@martijn86]

Everyone who is a little interested in good sound should try to get down to 16Hz. 16Hz-16KHz is soooo satisfying 🤩

[@TomKappeln]

11Hz with 18's here ...

[@jacemelridge6595]

Recently testing my car audio system I can't hear above 16KHz, though the RTA said it was there.

[@bitrot42]

Wow, never heard of these! Still rocking a PS Audio Superlink from the early 90s. It’s my favorite DAC of all time.

[@janelleflament5455]

Eminent Tech still makes really great really cool planar speakers! Absolutely still in business!

[@Paulmcgowanpsaudio]

Great! Thanks for that update. Much appreciated.

[@ianpeck2719]

Paul, you kill me with your analogies, “Fart in a windstorm”😂😂😂

[@emo65170.]

Found my way here by way of a KPOP video. Glad I did. Hehe. Great stuff!

[@thunderhousesound1974]

I used to have a Pheonix Gold Cyclone. Its exceptional sounding as a bass enhancement device. The benefits are high sensitivity so it doesnt need a lot of power and is super flat and very smooth yet punchy at the same time. It actually gets louder as it gets lower from say 90Hz to 20Hz. They were originally marketed for car audio and eventually went into the home theatre world and never took off. The downsides are they are pretty deep and need around 3cubic feet for a sealed enclosure. So the box is a fairly big size considering the airspace and speaker size. The only other thing i could see as a downside is that you can hear the air or flaps movement if the rest of the frequency spectrum is off or low level. But its definitely an experience to hear, i mean feel under 20Hz. We used to play Telarc and listen to harmonics of the synths at 10 and 13Hz. You wouldn't hear anything but could watch my interior of my vehicle shake cyclically.

[@kencohagen4967]

I’ve never heard of one, and it sounds intriguing!

[@NoahTheFacts]

I only ever experienced one in Niagara Falls, there’s a Niagara’s Fury 4D motion theatre experience. Conventional woofers handle frequencies down to about 39 Hz, and six Eminent Technology rotary subwoofers were drilled though the floor into an electrical room below that acts as a 5,000 cubic foot box. Each motor is ⅓ horsepower, fed by custom three two-channel custom amplifiers capable of below 20 Hz content. The installation can manage 5 Hz at 125 dB, even manages 1 Hz and it is indescribable. Well, I suppose the real thing is just outside. Special microphones were used to capture the sound for the presentation.

[@sharpsbattle]

Young guy made one and posted his experience a few months ago. Pretty impressive. Channel was Daniel Fajkis. “Making the worlds most powerful subwoofer.”

[@alanfenick1103]

The first time I heard a “rotary sub” used by Hammond Organ company. The bass was incredible. I believe CBS once marketed a separate speaker for sale.

[@endrizo]

No..not the same. that is the leslie rotary speaker that uses the doppler effect

[@Msardinas86]

I must be old but this is exactly what they use in theme parks like universal studios of Orlando to create that life like experience when your riding a 3-d ride.

[@mickybee3247]

A fart in a storm is the least of concerns: Weaponised infra sound has been explored and used! I think it's somewhere between 6Hz and 12Hz that effect the stomach - nauseousness, cramps, eyeballs bouncing around, headaches and generally feeling unwell. Now pump up the volume - experience being disembowel and/or brain turning into a smoothie! Really appreciated by the neighbours! Great video, as per usual :)

[@scharkalvin]

You're talking infrasonic here. You can make a conventional woofer that will go that low, but it's crazy. A friend of mine took a Piledriver 15" driver (don't remember the model, but it had a paper cone with a pleated paper surround and a HUGE magnet), and coated the piston part of the cone with several coats of epoxy. He then poured about a half inch layer of epoxy over the dust cap. This increased the mass of the cone, which lowered the FS to UNDER 20hz. (Yes we build a large box and MEASURED the T/S parameters before and after the epoxycation). The driver was mounted in a sealed box, about 20 cubic feet (size of a REFRIDGERATOR!) made of 2x4's and 3/4" plywood, and was driven by an amplifier of over well over 100W. We tested it with an HP audio oscillator (which went down to 1hz, had to test over TWO octaves). We could FEEL the output below 20hz, all the way down to 5hz! Yes this was a ludicrous design (we made TWO of them for STEREO), but my friend had a very large room and money to burn.

[@HareDeLune]

scharkalvin Wow. Reminds me of the story a friend of mine told about helping to install some giant Klipsch horn speakers into the concrete foundation of a *house* ! I can't even imagine what they sounded like. : P

[@Zack-dk3pt]

some subs can do below 20hz without crazy modifcations or setups like my 15 inch aria b985 which successfully produces deep deep bass down to 17hz.

[@thenextstepp]

Hare deLune I work in architecture (almost an architect myself finally) and when I was first getting started I saw the plans for a similar setup. The guy had these massive concrete columns, one in each corner of his media room and they were going to be setup in a similar fashion as you described. I only wish I had paid more attention, it would be curious to see those plans after all these years.

[@james8660]

Sounds terrible. points for trying though

[@rwj1313]

Most mastering engineers will use high-pass filters to roll off frequencies below 20 -25Hz. 99% of the population don't own speakers/amplifiers that can efficiently reproduce those low frequencies. There are certainly home theater systems that have subs that can go that low but they are not very efficient at really low frequencies. I think most people will only see those kinds of low frequencies in audio used as special effects for DVD's and BluRays.

[@eiserntorsphantomoftheoper2154]

My friend hired a MMA fighter to punch him in the chest each time there's a bass note. And it's conveniently 100% wireless.

[@tenorman]

What do you do with the MMA dude when you're not listening to music or watching movies?

[@philmac7474]

Paul you are a legend, thank you for your channel.

[@TheMB2333]

There's a particular segment of the US population that I believe has them installed in their cars.

[@chrisvinicombe9947]

Michael B. Ah the bass fiends. Every country has them 😄

[@jedpetersen3806]

Phonics gold produced something similar, I think it was called the typhoon. Check it out!

[@HareDeLune]

Michael B. Naw, most of 'em just have a box of hammers that rattles around. XD

[@BoarAudio]

Jed Petersen Its called Phoenix Gold Cyclone invention of Tom Danley, never really took off, probaby because desing problems they started to rub internally, revision never made. Tom Danley has his own company now Danley Sound Labs, but he havent yet taken cyclone back to production.

[@jedpetersen3806]

Boar Production right on yeah I knew it was something like that I couldn't remember what it was called but definitely was unorthodox for the car audio industry. Good times, the 90's!😁

[@moskitoh2651]

The newer ones are build into the walls. Negative: Outside they are equally loud. But they are actually cheap and small.

[@peniku8]

Just a small correction 6:00 the correct term would be "Infrasonics". Sub-sonic is a speed ;-)

[@michaelhillpot]

I believe the military used a fairly interesting subsonic speaker for testing the effects of sonic booms. Picture an air duct bent in the shape of a doughnut. At the bottom is a blower motor circulating the air around the ring. At the top is a servo controlled vane in the middle of the airflow that directs air out the front or rear facing horn. Really interesting design.

[@FOH3663]

michael hillpot The Tom Danley design?

[@garygriffith7053]

Two companies come to mind. Intersonics and Servodrive. I heard them throughout the hall at NSCA many years ago. They were astonishing!

[@tommcqueen2840]

I use a pair of Bag End double 18" inch with their ELF-1 processor. This setup will go to 8Hz (just takes power and the Krell amp makes 2000W @ 4ohms on each), but most rooms rattle and shake much below 14. Doors rattle in the frame, ceiling tiles can vibrate, anything hung on the wall dances, etc.

[@josephs1732]

Damn. I thought he was talking about submarines

[@loyddussault5101]

I own 4 servo/drive 7's They are servo motor driven speakers set in a folded horn cabinet that uses the backs of the drivers as the forward sound source.

[@richardlandgrebe4917]

a very good way to get those "Infrasonic frequencies" are with a "Tactile Transducer". They are perfectly coupled to your furniture or floor or a riser and are solid down to few hertz. Very common in theaters but i also use mine for "Novelty" music listening. Much less expensive than a rotary sub and they are silent while at rest. The Clark Technic (Platinum) is the same transducer used by the military in flight simulators.

[@snoopyjc]

Richard Landgrebe Yeah, I have 2 bolted to my LazyBoy!

[@richardlandgrebe4917]

Joseph M Orost , well I'm not the only certifiable sonic junky after all! I also have two of the platinum exciters bolted to my dual love seat recliner and it is absolutely over the top! (But of course it should be, considering 2 of those exciters will blow a thousand dollar bill) Thanks for your comment and happy listening (and shaking) Blessings, Richard Landgrebe Power House Sound Lab

[@richardlandgrebe4917]

With two exciters there is a real cool effect that you can do by inverting the phase on one side and the effect is this (one side will thrust in the up direction and the other will thrust down ) it is great for certain action movies 🔊

[@mikedegroff7766]

These are sold for drum thrones and are called "ButtKickers"; it allows the drummer to feel the kick drum even if he can't hear it during live performances. There is another variant that is placed under stage risers that serve the same purpose for other musicians, and they are REALLY useful.

[@garyhundsrucker7771]

That explains why when I went to demonstrate how the 4×12speakers sound so much better than the one speaker I had on my guitar amplifier it didnt come across that well on the vid.It shakes the floor boards and walls in my room due to the subsonics but it only sounded a little more "hi-def" in the recording!

[@janinapalmer8368]

Wish there were more good questions like this ...

[@timtravasos2742]

I thought I'd heard of every kind of speaker. Wow!

[@mephInc]

Check out the Phoenix Gold Cyclone. It was made in the early 2000s for car audio. It was a flop right out of the gate, but it still existed.

[@alfbeef5880]

I've seen and heard a rotary sub back in 1995 it shook the whole entire store that it was in..

[@Beos_Valrah]

Amazing!

[@a64738]

A free air infinite baffle speaker system (usually with an array 8 or more 12" and and larger woofers) will do the same but will also be capable of making very high fidelity bass from extremely low to higher up in the frequency range then the rotary woofer can manage. I used to have Celestion System 6000 dipole bass consisting of four 12" woofers mounted in a open air frame. It produced beautiful bass down to 20hz and lower but just like with the infinite baffle it needed 6db pr octave boost from 70hz and down. That is why they usually have many 12" or larger woofers in system like that to keep the cone travel at a reasonable level with so much boost at low frequency. Without the back pressure in closed enclosure the woofers do not need much power to move far so they bottom out very fast even without having a giant amp to drive them. With a an infinite baffle array of 8+ woofers you need to mount them on a manifold so they cancel out the mechanical movement or you will end up shaking your house apart while wasting a lot of energy and ruining the sound fidelity (even large concrete structures starts to vibrate when so many big woofers move 1 to 2 cm in sync). That is a mistake I see many do when they make a infinite baffle array.

[@GhostSamaritan]

Do any major studios utilize those woofers?

[@drkastenbrot]

no, we dont care much for anything below 20Hz, its 40Hz+ where much of the kick starts and most of the bass is really perceived by the harmonics at 100-300Hz. The super low bass these rotary subs can produce dont seem that useful for me in the music I create but I can see how they can be extremely cool for immersion in movies.

[@Dazdigo]

Rotary subs are essentially just helicopter rotor on a fan. Helicopters adjust the blade angle while spinning. Tom Stanton goes into great detail how they work in his "Drone Helicopter Hybrid" video.

[@glennchartrand5411]

Im in my 50's and I remember seeing those things as a kid Church organs used them for the really low notes and they were pneumatically actuated.

[@SpeakerBuilder]

Thanks for the info Paul, but the main point you made in passing is, at least for me and likely for most of us, none of the music I own and listen to has low end information below 25 Hz, where my current subs reach their limit.

[@keywestjimmy]

How would one know? I can think of a few popular songs that have 30 seconds or more of subsonics that people think is dead air. And this might be true for most vinyl, however, lots of microphones pick up 15hz So subsonics are recorded, just not reproduced.

[@Bassotronics]

You don't need a huge enclosure or sub to get down lower than 20hz. For example, I have a 15" subwoofer in a ported enclosure which has 3" diameter PVC tube inside the enclosure itself. The tube is approx. 80" in length and is so long that the 'tuning' drops down into the teens. Every time I play a 15hz tone in my vehicle, the bass bobbles my head side to side. I even have the same enclosure made for two 8" subs which was my first prototype and does the same thing.

[@mephInc]

Can, and doing it efficiently, are two different things. You can run a 5hz signal through any subwoofer, but it doesn't mean that it'll do it well. Clearly, you missed the part where he was speaking about the resonant frequency of the sub.

[@Bassotronics]

Bearistopheles Of coarse, bigger subs will have more mass which equals a lower resonant frequency. But doing it at the resonant frequency helps with getting the max efficiency out of the sub, but In the end, the resonant frequency is only one particular frequency and the sub will still struggle with all other frequencies regardless if it’s and octave higher or lower. It’s all in the enclosure itself where the magic happens. There are so many variables that explaining it all would take time.

[@mephInc]

You don't need to explain. I've been building SPL setups for more than 20 years.

[@StrangeDuck]

3" port is comically small for a 15" driver unless you are giving like 100 watts or something. With your port at that length you are tuned to about 9hz you could tune to 25hz with a larger port, gain bandwidth and a ton of output. Just my .02

[@Bassotronics]

ecoots Yes, 3 inch is a little small for a 15” sub but I was satisfied with the result regardless. If I make the port wider, I would have to make the tube longer And my idea for the enclosure was to be tuned very low and as compact as possible. One day I will use 6” diameter port and a longer tube and see what happens. 😀

[@tedleaf-pk2jc]

My next project is ultra low, high spl system built into a 50 foot steel canal narrowboat. My old pair of 20 inch jbls, driven by customised Marantz amps could make big ripples, small waves. A pair of rotaries, fitted through the roof, one at each end of boat cabin.

[@noobczsk8849]

I think that these type of subs are good to have in some home cinema , because it can completely vibrate the room and the feeling from movie will be much better :o

[@bilguana11]

There was a static display at THESHOW when it was still at the Saint Tropez Las Vegas during CES (that hotel is now something else: 455 East Harmon Avenue). He was talking about putting it in the attic.

[@Gr8Passion4Music]

I also have a question and it is that why aren't ribbon speakers popular despite their slimmer dimensions? I'm subscribing, kindly make a video on that also, thanks.

[@anthonybarker9123]

If anyone finds them on the west coast near Oregon. Evergreen Aviation museam (home of the Hughes Hercules) is using one in one of the displays. It's a pretty awesome experience, and a great museum to visit.

[@DancingWheels]

We made a quick and simple haunted house. Covered the 4 car garage floor with 4 inch thick foam matts, covered with thick heavy black plastic sheet. Like walking on a giant mattress. Hung sheets of black plastic for walls. Black lights and glowy bats on strings, fans blowing, it was very disorienting! I made a 1.5 second track of a T-Rex / alligator roar slowed down to about 18 to 22 hertz. When it went through the pair of Rockford Fosgate 15" Power subs and matching 4000 watt amps, people actually just fail over! It took a few seconds for them to recover. It literally removed your ability to balance! People said it could be "felt" 5 miles away! They were drawn in like zombies to brains!

[@sky173]

Very interesting. Thanks for the info. Sounds like your describing a helicopter rotor.

[@TomKappeln]

The Bell UH 1 "flap flap flap" comes from ultrasonic at the end of the rotor blades ... But these ultrasonic (boom) waves "CREATE" Infrasonic waves !

[@galtthedestroyer]

Install a tactile sound transducer into your chair or couch. They are incredibly cheap, incredibly easy to drive, and don't disturb anyone because you have to have physical contact in order to feel it.

[@BruceRichardsonMusic]

It's interesting to read the "why would you do that" posts. Infrasonic information became relevant as digital audio reproduction became mainstream and it was possible to master recordings without the need for blanket highpass filtering. In the studio monitoring world, Bag End was the go-to for years (still is, to a degree). They use a dual integrator circuit to create an eq curve opposite a small sealed box, then throw an 8-18 Hz variable highpass filter, large cone surfaces, and high amplification against it to create a relatively flat and nonresonant bass curve. I've used those systems in my monitoring chains for years and they are astonishingly effective. I also own a couple of the series II Velodyne "Coffee Tables" with a servo-coupled proprietary amplification chain. Those are effective to 18 Hz. The Bag Ends are technically flat to 8Hz if you have a room which can accommodate sufficient cone surface (and an amp closet which can deliver enough amperage and heat dissipation to stacks and stacks of amps). Obviously these systems are not relevant to vinyl reproduction. You've got to turn them off, in fact, unless you enjoy shaking your house and subs apart with runaway feedback. And to pre-answer the question "why," the Bag End systems in particular are quite valuable in a mix/master setting for creating bass content which plays well on speakers of all capabilities. Any of these "forced infrasonic" designs requires a protection mechanism, otherwise extension/burnout failures would be rampant. Bag End uses a design which reduces the fundamental pitch as its first line of defense. I guess the simplest way to describe it would be a smart multiband compressor with enough infrasonic granularity to be effective. The system provides visual feedback when this protection is working. That aspect turns out to be the great value in a mix/master situation. When we know exactly what frequencies will cause less capable/flat designs to overextend (ported cabinets, typically), we can sculpt those particular areas very carefully--working to prevent the Bag Ends from going into "protect mode," and therefore, achieving something much more subtle than simply high-passing the problem away. This is getting into the realm of psychoacoustics--working with the brain's ability to reconstruct missing or reduced fundamental frequencies when it hears their overtones represented at the proper amplitude. This, in fact, is why we often perceive frequencies that aren't actually there when we're listening to vinyl. If the partials exist at the right amplitude and proportion, the brain will apply them to generic rumble content to create the missing or reduced fundamental! Sorry. Maybe TMI, but I thought I'd add some thoughts based on my experiences with those systems. Particularly when I'm working with content that will be played in theaters with conventional ported sub systems, having a mix/master system capable of those infrasonic frequencies allows me to anticipate problems and actually get much better results (with fewer "trash" subsonics in the final product).

[@2davydo]

This Was a great read. I remember an old retired engineer telling me that you can construct a EQ. that can augment certain frequency's Harmonics that can trick one into believing that you are hearing really deep bass with vary small drivers speakers, He said that that that was how the Famous Bose acoustic wave patent worked was by amplifying those harmonics that are multiples of the fundamental frequency.

[@the_nondrive_side]

Bag End. I forgot about that company... The ELF subs. I think they worked entirely below their resonance because that was a known rolloff rate at 12db... Then They added another filter group for a passband to get the flat frequency and such. I can't imagine it would be musical but it makes complete sense. That was sooooo long ago.

[@BruceRichardsonMusic]

Hey, David Holland...Yes, correct. The ELF-1 used a dual integrator circuit to create that opposite slope with the least possible incongruity. The tradeoff of that system was the need for lots of "cone" and wattage. But I suspect you'd be flabbergasted at how musical it is. It's extraordinarily flat. You can choose to let it go all the way to 8Hz, if you've got enough of the cone/wattage (and a room that will allow that much energy to fully develop). I had an insane amount of bass trapping in my previous room, and ran the system with four 18" drivers in four separate sealed boxes. If I can find them, I'll dig up the SMAART analysis. I was able to get the signal from 12-100 Hz nearly flat at mix levels. People who heard that system would just have me play things over and over. It's an unusual experience to hear bass that low with no discernible peaks and resonances. As good as those old Velodynes sound, the Bag End system has more dynamic punch. The ELF-1 was highly configurable, such that you could set up an RTA at the listening position and tweak in small increments to get the crossover response just right. Unfortunately, that was an expensive box to build, and they followed it with rebranded "infra" boxes that still sounded great but didn't offer anywhere near that control (and made use of more DSP versus the robustly analog design of the ELF).

[@the_nondrive_side]

@@BruceRichardsonMusic I recall the specs pretty well considering it's been over a decade and possibly closer to two. The resonance was like 160hz or something so it worked fine below with the corrected passband. Good info not TMI. I've been re-porting everything I own since forever.. my current 12" is running only 29-56hz currently but it's a cheap unit filling in a 2.1 monitoring system... I'd never need the ELF. Been on many line array system setups as a stagehand over the years and I have a thing for cardioid subwoofers... A completely different animal

[@circuitsmith]

I had a chance to talk to Mr. Thigpen soon after he started selling these. We chatted about the motor choice and issues like cogging and hum. The system really needs a passage to the outside to baffle the back wave, functioning like an infinite baffle. Perhaps it could be simply mounted in a "window" between two rooms. One suggestion I made to Bruce was a shaped duct surrounding the fan, to reduce turbulence and increase efficiency, vs just the edge of the baffle board. To see what I mean Google-Image search "ducted propeller" or look at vintage Vornado fans of the 1950s.

[@argonman1]

Rotary subwoofers are very efficient at producing low frequencies, in fact the lower the frequency, the, more efficient the become. However, because the motor (fan) spins even when there is no call for it to produce sound (neutral) while operating , there is constant amount of noise (air turbulence) generated and this is not insignificant. This is why the rotary sub is often 15 to 30 feet away from the target listening room. The long chamber is lined to absorb some of the high frequency turbulence noise and properly designed, will improve the coupling to the listening environment. Highly effective when designed well. Cheers!

[@sergeantseven4240]

They work a lot like the collective pitch found on RC helicopters, in fact i see a 5 blade collective pitch head from an RC heli on that prototype picture. Ingenious idea.

[@paulanderson79]

Or a variable geometry turbo charger.

[@skepticalgenious]

That was a great explanation of how a rotary subwoofer functions. I assume many tweaks could be done to improve the efficacy. The fan blade material could be important. I am only hyopthesising however. I also love the low bass. I want to feel it deep through my body. Not simply the surface.

[@Ywhls]

The person who explained them to me called them "open baffle" subs. Pretty crazy stuff

[@MadDragon75]

I recall one in a local high-end car audio shop a few decades ago. It had the motor at the bottom facing up and it was in a plexiglass tube. Inside that plexiglass tube what is a spiral made of plexiglass all the way to the top. I did get to hear a demo and I can understand why nobody would want to spend that much money on something that they can't even hear. But that doesn't mean it's worthless.

[@mfr58]

Hi Paul, have you come across the Graham Holiman velocity coupled infra bass speaker? A design published in the UK HiFi Answers mag, back in the 80's I think. Goes down to a few Hz. Very room dependent as it pressurises the air in the space, so all doors and windows need to be closed. I've got a set of plans somewhere at home, can use 10", 12" or 15" drivers. Never got round to building them though.

[@D3AThCAl2DS]

seems like a subwoofer in an infinite baffle

[@smil3493]

@Paul ! Hi there. I’ve been following you on youtube for a while and I thank you for all your videos. I guess I can ask my question here : I’ve been an audiophile ( At least I think i can consider myself one... ) for a while now and I’ve always wondered how different people consider an audio setup to be a good sounding one. Is there any reference method or are there any recordings that the industry uses to evaluate a system? What does PS Audio use to evaluate a prototype product ( RAC, Amp or CD Transport ) ? By the way you should come and visit Iran, It is such a beautiful place with wonderful people and many audiophiles.... Many thanks, Aram

[@bjorn_moren]

Came here to learn about rotating submarines. Novel and interesting approach to spiral through the water, I thought.

When you need the brown note.

[@FeeLtheHertZ]

I remember seeing these in action in KZbin videos back in 2009... totally forgot about these. Now that's a BLAST (HA!) from the past.. Or ceiling. Whatever.

[@Neojhun]

Oh i have read about these Fan Like contraptions. But i've never heard one in person. Would be interesting to experience.

[@TheLostBear78]

hearing a very deep low note under his speaking. Took me a bit to realise it was there. Very nice touch (Or very bad recording with a large fan running in the background) ;)

[@jeremytravis360]

I have never heard about these type of speakers before. Personally I always prefer Transmission line speakers that achieved low frequencies through a long labyrinth chamber. I built mine from a Dr Bailly design union Keff bass units. I think a company called IMF built them commercially. A nice explanation though Paul Than you.

[@mephInc]

To run a rotary woofer, you essentially need to build a transmission line. You need to cancel out the noise made by the blades themselves, and you need to be able to tune it to efficiently play the 5-20hz notes. They simply aren't cost effective for what you get out of it.

[@fsj197811]

I'm not at all an audiophile and don't have the ears for it anyway. BUT! I did find this interesting. Thank you!

[@ADR69]

These have been around for more than 20 years. Phoenix Gold made one for car audio and I always wanted one but they couldn't get super loud

[@THESUBZILLA]

so it's basically the 4k tv of the subwoofer world. we can't see as good as 4k but I still want it. we can't hear that low... but I really want one!! i want to feel the bass!

[@JeffDeWitt]

I'd never heard of these before but it rang a bell. I seemed to remember an electric organ with a rotating speaker. After doing a bit of googling I found it, it was the Leslie speaker sold to go with Hammond organs (at least at first). According to Wiki the Leslie had a rotating speaker for treble and a rotating drum under the woofer for bass. en.wikipedia.org/wiki/Leslie_speaker

[@paulstubbs7678]

A different thing altogether, nothing to do with generating very low frequencies.

[@724horndawg]

Actually kind of interested in whether this subsonic bass brings recorded music to the live feel we audiophiles are looking for?

[@HareDeLune]

Brian For certain recordings of pipe organ music I would say yes. Edit: Now I think about it, perhaps also some recordings of music by Harry Partch. For other things, I think I would have to experience it first before I would know.

[@engjds]

Problem is CD cannot go much below 20Hz, and if you use a turntable, you will be picking up the worbling of the record, even new records have slight perturbulations. So that then leaves us with mastertape, dat or something like that.

[@nickwallette6201]

@@engjds There's no reason CD audio can't store DC. But your signal chain probably has several points of AC coupling -- at least one, between the output of the audio player and the input of your amp. The -3dB point of that interface depends on the design of both, individually and together, but can be as low as a few Hz. It's generally accepted as not very useful to couple anything below 20Hz, but it's wise to design with an octave or two (or, simply an order of magnitude) between the lowest frequency of interest and the -3dB pole, just to avoid significant phase shift and to completely clear the slope of the HP filter.

[@robhughesguitar]

Infinite baffle subs can produce useful SPL down to around 10-12 hz which is plenty for me. As we go through our remodel I'll be looking at incorporating one for the theater. My 2 channel produces good output at 25 hz which is fine for me for music.

[@willm1157]

Sir you are the man!