Science of Sound: Loudspeaker Enclosures 

It depends on the kind of enclosure you're using. The derivation is beyond the scope of this video. The goal here is to illuminate the capabilities and tradeoffs.

@@ElectronicswithProfessorFiore Thanks. Will stay tuned!

Thiele and Small, et al. published their work in the 1970s. There were many professional level woofers in the 100 watt+ region back then. In fact, I recall designing some vented PA subs circa 1981 that used 18" Gauss drivers with dual spiders, 4" VC, handled 400 W RMS, and had an efficiency of 2%. I used a computer program that I wrote (for a DEC VAX 11-780!) to model it using the TS equations. The design was a complete success. (Side note: That program was reworked and ported to the Commodore Amiga PC in the late 1980s, and sold as "SpeakerSim"; the first product that my company, dissidents, produced). When it comes to skepticism, I am generally not confident of claims of continuous power dissipation of several kilowatts. At least not in terms of useful dissipation. By that, I mean that it is easy to get a driver to withstand that power, but is it being used effectively?

@@ElectronicswithProfessorFiore well I personally feel that a 100lb sub rated at 5k RMS with a voice coil that is 8 layers and 100mm tall winding height and ways over a pound for just the coil windings and has 5 to 8 extremely thick spiders stacked together is in no way regardless of the application it is being used in it well never be as efficient as a same diameter 400 watt RMS speaker there's just no way so I agree with you there Now why do they make 100LB subs? Because if the power is available but the space is limited and the goal is maximum DB's then efficiency is outweighed ( no pun intended) by power handling and the ability to move more air (some 100lb subs can have 100 to 120mm of usable peak to peak throw ) and so with a limited space (a vehicle) and a goal of highest DB's you can put as many 400 watt subs in the vehicle as you want but the vehicle that has the 100lb subs (assuming box specs are correct for each vehicle and application the extremely inefficient super heavy behemoth subs will reach a higher decibel level solely on the principle that lack of efficiency can be made up for in raw power handling and air displacement so the end result being a higher decibel level than the vehicle with lower wattage subs despite the 1/2 or 1/4 percent efficiency LOL But I question the way we because how can the computer read the specs of a sub that's so stiff you can stand on it and it takes 800 watts RMS to even see the cone start to move so how can it tell the FS and all the other parameters feeding it 2.8v/1watt? I just don't understand how it's getting trick feedback from such a small signal in comparison to the thing receiving the signal And to your rebuttal by saying you built some boxes that did great I will say this I've been making my own boxes for about 15yrs and I've never used the TS parameters to calculate what size box in tuning frequency to use and I have a reputation for how good my box is sound and side by side my box is 10 to sound better get lower and play louder than boxes supposedly designed for the specific speaker sometimes and especially they sound a million times better than a q power or a pro box that you can buy online those things are just trash So my point being that it's a fairly generic situation making a speaker box yes if you have a specific goal then that can require some unique design but generally speaking there's a pretty broad band of usability just like all humans seem to wear clothes eat food and sleeping houses there are a few that don't but the majority do.

@@SheikhN-bible-syndrome First off, you cite a driver with 1/4% efficiency. I would much rather have a 2% efficient driver (like that Gauss) that handles 400 W than one with 1/4% efficiency that handles 2 kW. Why? Well, from the first one I can get 8 acoustic watts with a 400 W input, and the second delivers only 5 acoustic watts yet requires 2000 watts to do so. And don't forget, you need to account for that increased input power, plus the heat that will be generated. Second item, you are suggesting that the parameters change under load, e.g., that a measurement of Fs at one watt will not be accurate for higher SPLs. What you're really claiming here is that the transducer is wildly non-linear. If that is the case, that's not a driver you want to use in the first place. Granted, some non-linearity is expected when the transducer gets near its thermal or mechanical limits, but if you find that Fs has shifted from say, 30 Hz to 45 Hz when moving from 1 W to 100 W, you're looking at a transducer that probably belongs in the dust bin. Third, I am not saying that it is not possible to design a system without using TS parameters. Of course you can, and it's possible to get good results, too. But the TS system makes things easy(er) because now we're applying well-established electrical circuit analysis techniques to an electro-mechanical system. Speaking as an electrical engineer, I like that, but if you have found some other methods that work for you, great.

@@ElectronicswithProfessorFiore I think your missing my point and I pulled that 1/4% out of my you know. > was just using an extreme as an example. that gauss speaker you had only has a xmax of I think 3mm if I'm not mistaken and will sound great on just 100 watts I can see a DATS v3 being able to read it's parameters but my point is I can't see it being able to read a 100lb sub that you can't even see the cone move when it does a sweep test and the cone doesn't seem to move at all despite being able to move 4" so then how can it tell things like fs as well as thermal limits /tech? I just can't see that being possible and that's probably the opinion of whoever came up with the Klippel test where they feed the speaker however much is needed to bring it to it's limits

@@SheikhN-bible-syndrome If I recall correctly, that Gauss driver was an 18" designed for professional PA and had an Xmax of around 25 mm, but that's beside the point. Please correct me if I am misinterpreting your statements, but it appears that your argument boils down to "TS parameters measured at low input powers are not accurate when compared to those same parameters measured at much higher input powers". If that is the case, then effectively you are arguing that the transducer under test is not particularly linear across its operating range. A non-linear transducer, by definition, is one that will produce considerable distortion. No one wants that, and reputable manufacturers try to avoid that where possible. Granted, it is true that non-linearities will become more apparent as the transducer is pushed to its thermal and mechanical extremes, but that's not where we operate the device normally (if we did, we'd have to conclude that the system design was subpar- as I'd often tell my students, no one wants to be hanging from a 200 pound test rope if they weigh 195 pounds). Regarding Klippel, I believe the major goal of the Klippel NFS was to perform tests without the need of an anechoic chamber (although it can do other things as well).