OK !
i put both the $249 JBL and $369 Dayton ( both 18" ) into 10 cubic foot box tuned to 20 hz.
here is the efficiency of JBL:
and here is the efficiency of Dayton:
now we will average from 20 hz to 80 hz but keep in mind that energy begins to fall off starting at about 40 - 60 hz and is typically significantly down by 20 hz. so we have to give more weight to the 40-80 hz octave than to 20-40hz octave.
JBL averages out to 3% and Dayton to about 1% … so JBL is about 3 times more efficient for typical movie content - no surprise there - that’s direct result of having lower moving mass.
but is there any frequency at which Dayton is more efficient ? well yes … Dayton efficiency peak ( corresponding to impedance peak ) is at 30 hz while JBL peak ( also corresponding to impedance peak ) is at 50 hz … so at 30 hz the Dayton is more efficient than JBL … but note that peak efficiency of Dayton is less than 3% while peak efficiency of JBL is over 12% and is also wider …
but the real argument i was having with Bill Gates was which one is more efficient at low frequencies … even Bill Gates would not dispute the JBL will be more efficient at frequencies above its Fs … his argument was that because Dayton had lower Fs it would be more efficient at low frequencies …
looking at the very low frequencies i have to admit the Dayton edges out the JBL slightly there - so was i wrong ?
yes and no …
remember my contention was that prosound drivers have higher force factor … and Bill Gates argued that they cost more … so i picked a low-cost prosound driver to make things fair … well this low cost driver actually has LOWER motor force factor than the Dayton …
to be more precise JBL has a BL of 18 with Re of 5.3 ohms for a BL^2/Re motor force of 61
Dayton has a BL of 23.8 and a Re of 4.4 for a motor force of BL^2/Re of 129
so actually the Dayton has double the motor force of the JBL and that’s why below resonance it is more efficient than JBL while above resonance the JBL is more efficient due to lighter weight cone
so how did this happen ? how did a home theater driver beat a prosound driver on motor force factor ? well it comes down to price. i used one of the cheapest 18" prosound subwoofer driverss at $249 whereas the Ultimax is actually one of the higher-end 18" home theater subs at $369 …
never the less, the cheaper $249 JBL still beats the $369 Dayton on average efficiency from 20 hz to 80 hz, but it loses below 40 hz and i said it would win - so i was wrong there …
my mistake was to use wrong driver as example - i went with the 2279 simply to make a point that not all prosound drivers are expensive. however the reason the 2279 is so inexpensive is actually because it’s not a real subwoofer - it’s a woofer in subwoofer form. exactly the same motor that is on the 18" 2279 is also used by JBL on the 15" and the 12" which are both used in 2-way speakers in the SRX 800 line crossed directly to a compression tweeter.
i knew all that and still used the 2279 as example because of the low cost … and ended up overstating my case … which admittedly happens sometimes when you’re going with the “shock and awe” debating strategy …
the $249 JBL 2279 is used in the number 1 highest rated subwoofer on Sweetwater:
https://www.sweetwater.com/store/detail/SRX828SP--jbl-srx828sp-2000w-dual-18-inch-powered-subwoofer
but despite being number 1 highest rated subwoofer and a great value i still ruled it out for my personal use because i knew the 2279 was not a true subwoofer driver … instead i picked Eighteen Sound NTLW5000
https://www.eighteensound.it/en/products/lf-driver/21-0/4/21ntlw5000-4
unfortunately because the NTLW5000 is three times the price of 2279 i couldn’t use in my argument that prosound drivers are better value than Dayton and used the 2279 instead …
i was too lazy to run the numbers on 2279 and Ultimax before making a wild ass guess that 2279 will be more efficient at all frequencies … which turned out to be not the case due to relatively weak motor of the 2279 … it is one of the weakest motors found on a 18" prosound subwoofer … but then it is also one of the cheapest.
as i told Bill Gates there are no miracles here. everybody faces the same physics trade offs. the reason i assumed JBL will win is because JBL only has to optimize for physics while Dayton also has to optimize for aesthetics ( it has to have fancy looking cone whereas JBL is behind a grille ).
this fancy looking cone adds weight to the Ultimax which i assumed would handicap it enough to allow the cheaper JBL to pull ahead. and indeed it does but only above resonance frequency. below resonance frequency mass doesn’t matter - only motor force does, and the more expensive Dayton has more motor force than the cheaper JBL and as a result it pulls ahead below 40 hz in efficiency.
i made a mistake. i admit it. i am always the first to admit my mistakes. i don’t wait until somebody catches my error.
this Dayton Ultimax VS JBL 2279 comparison has turned out to be less one sided and far more interesting than i thought it would be. Dayton was crippled by the fact that it’s a Dayton but the JBL was crippled by the fact that it was just a 18" version of the 12" midbass used in SRX 812 2-way …
JBL used the same motor in the entire SRX line from the smallest 2-way to the largest subwoofer in order to also be able to use the same amplifier modules or to have similar voicing or for logistics reasons of not having to stock extra parts at the same assembly location or whatever other reasons. this is why the 18" is so cheap but also why it isn’t so great of a subwoofer.
i’m going to call the Dayton Ultimax vs JBL 2279 a draw - both drivers are heavily compromised. Bill Gates actually successfully stampeded me into making a mistake but then he failed to capitalize on it by panicking himself believing he was losing and resorting to ad hominem attacks.
there are lessons here for both sides …
but at the end of the day i learned something and Bill Gates learned nothing even though he could have potentially learned a lot but he allowed his emotions to get the better of him …