Isobaric subwoofer box design
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- Опубликовано: 27 сен 2024
- In this video I want to explain how the isobaric loading works. Besides the theory, I am also going to make some isobaric enclosures and see how they measure, to test if the theory holds true.
Learn how to make speaker boxes, acoustical measurements and passive crossovers :
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6 different enclosure comparison : • Sealed vs Ported vs Hi...
How to measure T/S parameters : • How to measure Thiele ...
Music Credits:
"Werq" Kevin MacLeod (incompetech.com)
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Jesus. first time viewing your channel. This was one of the best videos I have ever seen. It was short, not useless chatter. It stayed on topic to the point of razor-sharp accuracy. I am blown away. Pretalk with set goals, A quick "behind the curtain" viewing of construction. Then detailed results. I am simply blown away. Thank you so very much. Wish you the best...
Easy to understand explanation, with a visual demonstration. As a 64 year old neophyte to speaker building and design this has been very helpful. Thank you!
The added benefit to isobaric clamshell coupling was to reduce deep bass distortion under higher power, aside from the supposed space savings. When a woofer reaches it's mechanical limits, assuming it's not catastrophic, the voice coil is further away from the magnetic field. When coupled, as one woofer is pulled in, the other is pushed forward. These speaker cones then worked in an acoustical coupling to control the physical extremes of voice coil travel. I've not tested that theory. I recall reading it in a speaker design book.
M&K Speakers used this idea in their subwoofers from the 1970's. There was a period of time when they were out of the market, but are now back into production. The woofers are arranged in a push-pull driver configuration in order to cancel harmonic distortion, according to the company.
I claim no special knowledge, merely reading what other designers claimed.
excatly! not only reduce distortion, and cabinetsize, but also easier to damp mid and low frequencies, since the box is so small.
M&K subwoofers are not isobaric. They even say that on their website
I’d like to see you make a 6th order isobarik band pass with as small a box as possible.
Sounds like a puzzle
Problem is the port size will make it large
Ok I'll build it been my idea for ever
I love this guy! Your videos are absolutely brilliant and very helpful for us common idiots in the audio world trying to get an understanding of it.. You have got to be the most underrated youtuber channel I've come across in my years of watching. You deserve way more credit, subscribers and recognition than you have now. Very helpful and I just wanted to say thanks for what you do for people like me coming here trying to learn.
Got that zhieeeet rite bro
Hello. Thanks for the video. This is exactly my case, as I happen to have a couple of 6.5" woofers laying around, and I would love to embrace an audio 'engineering' adventure, in a near future. My goal, would be to build two enclosures for them and use them in my home audio system, for movies and music. Obviously, i will have to cross them with a couple of mids or tweeters. I don't want them to be extremely loud (definitely not for SPL), rather I would love to take the most out of them, in terms of quality performance, and preferably that they would be able to play as low as 28/30Hz. I've been reading a lot about designing audio enclosures, but I am having a hard time chosing the "best" model that fits my needs. Between sealed, ported, transmission lines or tappered lines, 2nd to 8th order bandpass, I am just afraid of building something that won't make sense. I don't even have the TS parameters yet, and I am seriously thinking of order something like the dayton audio dats to get them, just for this project. This is how serious I am :)
Anyway, I would love to hear peoples' opinion on their own experience and how their own projects came out. Thanks.
Wow, great video! I already had an intro to the topic, but this was still very helpful. Fun build sequences as well. As others have said, I liked that it was straight to the point with no filler. Good stuff!
Awesome, really awesome!
I would love to see you design a small Bluetooth or similar speaker modeling and testing effect of passive radiators .
I have been playing around with designing a 3D printed enclosure from old JBL flip parts and I must say that your sound card T/S parameter how to video has helped a lot!
Thank you very much!
Использую изобаром в валящем проекте 150+ db
Тема хорошая. Знаю о ней лет как 8мь уже. Только год назад решил опробовать😁
Direct and to the point, you just got yourself a subscriber
Excellent video. Thanks for all the hard work.
very nice and inspiring - found your channel when had to measure TSP (which I already did several times but forgot how to do it)
and now I see you have plenty of nice videos and experiments - keep going ;)
Excellent educational video with both theory and real world results demonstrated!
Super informative video! I was just thinking to make an isobaric with 4 6.5" speakers
You are always ma number 1 teacher. 🥰
I just found your channel
It's so informative
It would have been very useful to expand on the earlier part about the voltage being across both voicecoils, when wired in parallel. Since this means that you are dissipating the same power in BOTH drivers the sensitivity of an isobarik is 3dB lower than the single driver design. There is no free lunch in this case and it’s important to understand this issue with this design method. You halve the box size but, you halve the efficiency.
Expecting more videos from u , I am following ur website from years ago
Hi, this is very cool! But do I understand it right - you gain a smaller Box but have to drive it with the double ammount of power to get the same sound pressure out of it?
Exactly
Have you or can you make a comparison between an Isobarik and a Bandpass speaker? If I am not wrong you said at the end that it was more interesting the BP over the Isobarik. So I'd like to check speaker response and other parameters, if it's possible.
I found that the sound quality in a linear (cone to magnet) to be superior to a single woofer, especially when you add sound absorbing materials to the lower portion of the box. This helps to get closer to an infinite baffle adding to the quality, just my experience. I used a 1 cu/ft for a 10" woofer and about .5 cu/ft for the upper. Good explanation.
Great video thank you. Does the inward facing drivers radiate sound into room as well? I gues they do because of the measured volume?
Yes your explanation is very clear
Your bass is faster and more accurate. Clamkshell are to be wired out of phase as to help each other push pull. In my clamshell, My 12’s are as fast as an 8 and hit low like a 15. Also I suspect that you can push it a bit harder and use a bit more amp power.After all what we are trying to do is move air without distortion. I may be being fooled, but clamshell seems to have less distortion. These to me are improvements that make it well worth doing.
Please explain the term ‘faster’ as pertains to reproducing bass frequencies.
@@whodat90 good question, I'm no expert but as he hasn't replied I'll try to answer. Speakers take time between movement of the driver for the sound to reach our ears, a problem that you can run into when tuning a speaker box is that even though a speaker may hit very low frequencies, it can start to take considerable time from the speaker moving to the sound reaching you, this usually is a problem with longer speaker ports, becuase the air takes time to travel the port. This also means that the speaker risks cancelling out its own produced frequencies. This is to do with something called speaker phase, have a look online at speaker phase if you want more info.
BEST PART IS 1:02
🤣🤣🤣
It would have been cool to see in a huge home theater box of 25 to 35 ft3, where halfling the enclosure size is YUGE difference.
Hi Marius! Thanks for the good videos and useful information! What about coaxial pro audio drivers? It Would be an interesting project
W hat if one cone from a sub is removed and the coil is directly connected to drive the Cone of the other sub?
What would be the difference?
Essentially one cone being driven on both sides by two motors
Bro, great article. I am thinking of building a small speaker for my workplace...it's what we do, ha. So being small, isobaric is a mode I am considering.
As a future project??? The Decware modified Jensen Imperial. I built two of them, utilising the cheapest of ingredients and I have never heard anything come close. I am looking forward to building a pair using decent gear. I better hurry up, I'm 58 this year and Covid has put a blocker on so much.
Great informative video! Looking forward to the next one!
Slightly off topic question, what if the speaker inside the enclosure is not connected to the amp? Does that help with the dip in response around the speaker resonant frequency? Is that better for bass response?
Awsome demonstration on the topic but I am a little bit sad sad you did not coat the outside of the MDF.
Because you do know MDF leaks air? First time i bought MDF as a kid on the country side I had to go to this furnitur manufaturing place.
They had this vacum table where you just line up som rubber in threads on the metal table, and it got a lot of holes to make vacume to keep plates in place while they cut them.
So this guy showed me; He took a pice of MDF 50X 50cm lined up the rubber for suction in that square. Then he turn on the vacum, Took a new pice of MDF ca 20X 30cm and thow it on top and said try to move it.
It was totaly impossible for me to move or push any way. It was sucked thorugh the other pice.
So a quick layer of lack or any coating would help and then the rest of the MDF give a nice damping in the enclosure.
So your measurments will be off in reagard to cabinet leak.
That is very interesting. MDF is a porous material and will have some leakage associated with it. But not something to factor in. I mean, even the speaker driver itself will leak air through the cone, but nobody accounts for that. Anyway, I still find it hard to believe what you are describing, even if they were very thin sheets (3-4 mm). I'm guessing some other phenomenon is going on which is not evident right away. If I were to make a guess ... MDF has a very smooth surface, and when you stack 2 pieces, they naturally form some sort of void between them anyway. And since the sheets are pretty heavy, it's not an easy job to separate them, even without the suction machine. So, if that machine would manage to suck out the little air that is left between the sheets, it would explain why you couldn't move them. On another note, MDF is perfectly fine for speaker boxes without any treatment. It's one of the top materials of choice.
The “k” Komes from LINN Produkts. I’ve had the LINN Isobarik Sara’s, the Isobarik DMS / PMS. (Active) and now have the Keltiks (active)
Thanks. Nicely done.
In a German hifi forum some people claimed that the magnet to magnet compound would be the best, because of the combined magnet forces. Not sure if that really makes sense.
Great video.
For a 6 1/2 inches in-ceiling home speakers, what would the dimensions be for the speaker enclosure ?
Thank you !
In-ceiling speakers don't need an enclosure. You just cut a hole in the dry-wall and mount the speaker there. They are designed to work in free air / large enclosures.
How about a coaxial horn with acoustic lenses? Digital crossover using fir filter for linear phase alignement...
Awesome channel. Thanks everything 👌👌
Subbed and i'm going to watch all your videos 🤩
Are there any speaker characteristics that would make them not-ideal for isobaric mounting?
Nope. Any speaker can be mounted in isobaric configuration.
This video is excellent but puzzling because it seems to contradict the fact that isobaric bass guitar speakers (orange smart power OBC212) and isobaric hi-fi speakers sound BIGGER than single speakers in a box.
What happens In cases like M&K and Perlisten subwoofers where the rear sub is basically infinite baffle or ported is it still isobaric? And how does it affect the response or parameters?
Nice shop. Why does it look like there are stickers on each panel of the cabinet?
Also, clamshell isobarik has the added benefit of canceling any response nonlinearities the speakers may have along the x axis.
The company which provides me with MDF has cutting services as well. So I calculate the boxes beforehand and order the panels to the exact size. The sticker contains the dimensions and panel name.
Great video!
Love this video, maybe a stupid question but, can this be applied to low mid's as well!
You can, but usually they work in small (usually sealed) enclosures. As a result the benefit in negligible and the cost is an extra driver.
This is what i am gona do.....I will subscribe ...and thums up
i like the idea of the Pioneer TS-WX70DA do you have any idea how to redesign this inclosure for better drivers?with one big woofer to get lower fq. greetings
Hmmm... great video!
You forgot to mention the only and to say the biggest advantage of isobaric boxes and drivers connected by opposite polarity and that is the cancellation of harmonic distortions
I think should explore the transmission loudspeaker
You seemed to gloss over that the brown curve (25 liter flush baffle) exibits some nasty waves blow 35 Hz. Might be worth investigating.
Nice
Nice video! Question: on the Isobaric Clamshell, are the speakers wired in parallel and are the wires between the two speakers crossed so that one is pushing and the other is pulling?
Yes
Yes, one is wired in reversed polarity.
I have an older pair of Rockford Fosgate 18 inch subwoofers I was contemplating on building the clamshell for these considering for good response they seem to need 8 ft.³ ported it at 31.5hz I believe the spec sheet calls for 4 ft.³ sealed so in theory if I was using two of these in a clam shell configuration when I knock that down to 2 ft.³ per subwoofer or make it a little larger and go with 3 ft.³ if you actually answer this I can get you the model number of the sub woofers
If you did a clam configuration and each woofer should get a 4 cubic foot enclosure you should put the one woofer inside a 2 cubic foot box. Make sure you use a thick separating ring so they have some air to share. The clam shell configuration is actually preferred due to the woofers working in tandem 180 degrees phase shifted. This will eliminate any distortion introduced by the driver itself by cancelation. I'm actually doing the same thing with 2 Kicker Comp C18A's. Kicker never made a solobaric round back then so I'm making my own. I might use 4 if sounds good or use all 4 in a normal configuration if the isobaric box doesn't impress.
what about sound quality?
Hey! I have a question: what would happen if you kept the box 100 l but added another speaker in clamshell configuration?
It will act like one speaker in a 200 liter box.
@@AudioJudgement Thank you for the reply! How would that affect the loudness? I.e. would that setup be louder than a single speaker or the same?
Not really. If you have 2 speakers and looking for loudness, you would place them normally and make them share the same enclosure. Placing them in isobaric configuration, you just make the box size requirements smaller, and only one speaker radiates sound on the outside, which is just a waste in this case.
Dont go with maths.....go with your instincts....sometimes......
In which kind of boxes we can get maximum bass
Bass reflex, 4th order bandpass, 6th order bandpass are all good candidates. Depends how you design them, because each box is a compromise between size, efficiency and bass extension.
I like it but not convinced me. So, I need the "I don't know" button...
Great job. Serious.
Thanks!
You might have som losses as reason for differenses in measurements.
if its good for my ears ,i buy it
no worry if it is isobaric or barbaric
Clamshell works best with a ported enclosure due to them being larger than sealed. Halving a large enclosure is great, but halving a smaller enclosure is a waste of time, as demonstrated in this video.
I have an interesting idea. How about I merry you you beautiful speaker freak!
😂
Isobaric also doubles power handling which can in theory gain you an extra 3 db if you double the power.
Please bear in mind that half of that power goes to a speaker which doesn't radiate sound to the exterior. Therefore you don't get any output boost.
@@AudioJudgement So how does motor force factor into spl? If you have twice the power and twice the motor force. You could also build a large enclosure and effectively double the size. So basically If you have motor motors with twice the power and an enclosure that is twice the size would it be louder?
@@MrHannible Actually BL is the same for a parallel connection. Bl^2/Re is indeed doubled. But you can't take just portions of the equation. You have to take into consideration all the factors : the speaker is twice as rigid, it has twice the moving mass etc.In the end, the isobaric configuration is more inefficient. If you give it the same power as one single speaker you will have -3 dB SPL. Only when you give it twice the power it will have the same output as one single speaker. What concerns the enclosure size : If you have 2 enclosures of the same size, one is with one speaker in normal config and the other with 2 speakers in isobaric config. Yes, the isobaric config will be louder, as long as it receives twice the power.
@@AudioJudgement Ok great now is there a way to approximate how much louder it would be in the example 1 woofer vs 2 in the same size enclosure with twice the amount of power thanks for the input.
Yeah. You can use any modeling software (like WinISD), model the response curve of each box, and compare them.
You are goood man
Super
I have this type bass in last 6 year
I'm thinking that because air (a gas) is compressible it makes for inefficient transmission of pressure between speakers, transforming pressure into heat inside the enclosure. What if the sealed space is filled with an uncompressible fluid (liquid)? What if it is pressurized gas?
What speaker burn in program do you use
You just play a test tone which is the resonant frequency of your driver. Then set the volume so the speaker moves with decent excursion. But not too much, that you feel uncomfortable that you might damage the driver.
If im going to make a cone to magnet design i would make the inner speaker move way to the back and put a port going to the front that way it would be heard loudly. like the box looks like an L Port but theres a secret speaker at the back. I will not tell anyone there's a secret speaker at the back 😆
Or it'll look like a hog scoop box with a secret speaker in the back 😁
No one really uses iso anymore... The only reason would be for a super tiny space but the more practical is show application BC no one really wants to waste money on an extra sub or show off a magnet for anything other than promotional reasons... Plus magnet to cone just looks like one speaker and is weird. The only benefit is half the box volume and decent freq response... Not twice the output...
So the smallest form factor box would be isobaric and a passive radiator hmmmmm small bluetooth speaker idea
All if these speaker configurations will get you beaten by a cop in Texas.
You remind me of the YT’r “Life of Bliss.”
Keep doing what you’re doing. Minimal but essential words that compliments what we see as opposed to adding tons of info that serves to confuse and/or overwhelm the view.
Your choice of words are clean so that I’d be ok w/a 4 year old watching! Delivery is even paced that helps the viewer overcome that English is not your first language.
You don’t waste energy “injecting” your personality into every facet of the video. I watched several of your YT, never heard any foul language.
Another YT’r injects his annoying verbiage habits so much that I stopped the vid. Another still, while informative, too much personality and profanity that makes the view longer than necessary.
Bitte in deutsch
Tak tuku be
good information, however your audio editing leaves a lot to be desired. when you have the music loud, and then you whisper to me like this video does, it makes me think you are trying to make me watch it multiple times to cheat the number of views.
Deutsch ?
C. Z z
Thing i like abour isobaric subwoofer is it can get crazy low like 28hz only using 6inch woofer 60watt inch 8ohm. Model subwoofer i use it Polytron Psw500c an old school hometheater subwoofer.The sub is crazy good at low frequency and easily can feel the hard heavy bass on your chest at low volume . The weakness isobaric is at punchy bass .
what happens when you build a box with 2 4 ohm woofers mounted with their magnets facing together but one out of face and both wired on a 2 ohm load (a sort of push pull)
You are not very specific about how you arrange the woofers. If it's an isobaric config, it will work like any other isobaric configurations mentioned in this video. If you just have 2 woofers sharing a box (as in, you can see both cones of the woofers from the outside (on the isobaric config only one woofer radiates sound to the exterior)), the fact that they are push pull, they will cancel each other out and you have a terrible subwoofer box.
@@AudioJudgement
one 4 ohm woofer in the front of the box and one 4 ohm in the back of the box so the magnets are towards each other and than wire it at 2 ohm and wire one of the woofer out of face
A carefully designed the clamshell configuration allows a smaller box, as shown in the video, but has a particular advantage in reducing odd-order harmonic distortion. This is especially true if the woofer lacks any distortion reduction features such as shorting rings or an extended pole piece.
Suppose, for example, that the motor has a simple motor with a pole piece that's flush with the front plate, and no shorting rings.
When the voice coil moves out, it moves more of its windings into an area with a weaker magnetic field. As the voice coil moves in, more windings are exposed to a stronger magnetic field.
This means that, for the same signal, the speaker sounds different when the cone is moving out than when the cone is moving in, and both are different from the signal the amplifier sent. This is what we call distortion.
If you take two of those drivers, put them in a clamshell configuration or back to back, wired out of phase, the unequal cone movements in and out will balance each other to some extent, making the sound produced more like the signal sent from the amplifier. In other words, the distortion is reduced.
If, however, the driver has an extended pole piece or, better yet, shorting rings on the pole piece, the distortion is going to be lower anyway, so the push/pull configuration may not be worth the expense.
There is still a problem with an extended pole piece in that the movement of the voice coil changes the magnetic field in the pole piece, causing distortion. The shorting rings largely shield the pole piece from these changes. So the extended pole piece will have more distortion than a well-designed driver with shorting rings, and may still benefit from the push-pull congfiguration.
In this comparison video, it would've been best to also put both speakers in the 50L box, in the clam-shell configuration, and then measure it to show the big increase in dB that is achieved at the 20Hz-60Hz range.
Series - BL doubles, Re doubles - (BL)^2/Re doubles (that of one driver)
Parallel - BL the same, Re halves - (BL)^2/Re doubles
Sd the same
Rms doubles
Что важно в изобарическом исполнении ещё снижаются искажения, звук становиться точнее.
isoberic is non-sense, except when front to front, then some improving magnet non-linearity
Basically twice the money for a smaller box
What design is M&k push and pull subwoofer?
When I set up a pair of isobarik drivers in WinISD it cuts the efficiency in half. Why is that? Does WinISD automatically assume you're connecting the drivers in series? How do I fix that?
great video ! lots of work put in it. how about the "force cancelling" features of the push push (magnet to magnet) design ?
That is not an isobaric design. You can use that in sealed or bass reflex box for example. Where you basically have a dual woofer setup but they are placed on opposite panels. And when the front one moves forward, the back one moves forward as well, but since it's on the opposite panel it moves into the other direction. In this case it cancels the vibration induced to the box. And no matter how violently the woofers move, the box will remain perfectly still.
In an isobaric design, when you place the woofers magnet to magnet, you have to wire one speaker out of phase, so they move in the same direction, so the "force cancelling" doesn't happen.
Postati si in romana va rog.
Does this mean that if you keep the same sized box you can have a lower frequency using the same box?
Depends on the exact situation (speaker specs, box size), but most of the time, yes.
Unfortunately, you do not take into account that the air in the coupling chamber also has a weight. This is the reason for the shift of the resonance frequency with larger volumes.
Thank guy🎉
1. I have been leaving comments last few days as I have been practically binge watching your videos.
2. I have been viewing audio stuff on yt fro the last 4 years and the stupid algorithm never recommended your work.
3. Awesome work, keep it up
4. Most 'audiophile' yt channels would dedicate 3 episodes to building 1 sub, showing off glossy finishes they are trying to achieve, but you explain the concept in half of the video and then quickly make 4 boxes in other half, not just in this video but also the one in which you measured 4 subs in your bmw trunk.
5. Does your dad have a wood/mdf shop? 😉
I'm using some space at my dads factory but the tools are my own. While he is in the woodworking business, none of the equipment he uses is useful for me. Except for an air compressor :)
I thing u should make open baffle speakers......Danny Richie from GR research is designing some ....seems to know what he is doing......u should try as well
They way it was explained to me back in the late 80s early 90s by the car audio rep for crunch which made an isobaric tube he said that the two speakers actually can handle more power not necessarily less space and true efficiency of a 10” crunch sub back then require a 6” gap in the clam shell between speakers never put the cone to cone with out having at least a 2” gap between them you don’t want them to touch but they didn’t ever really sound better so they only made the iso tubes a short time but great video
Not to judge but you look really tired. Im not sure if you are but, i hope you get sleep👍
Great videos man keep up the god work😀
What about facing a subwoofer in to the trunk and blocking it off and putting a hole on the backside which is facing in to the car will it still push the bass?
Can you help me to make a 8" 4th order bandpass subwoofer.pls give me a plan pls