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Hoffman's Iron law, if its new to you and your an audiophile, bass head or audio anything you need to grasp this information. its like a law of physics, in that equation there is size, efficiency and low frequency extension and you can have two any two but the third component will be the opposite of what you would want. so if you want loud/efficient and small it will not play low, if you want low and loud then the subwoofer and or enclosure will have to be very large, if you want small size components and low frequency extension than it will not be very efficient or in other words it will require a lot of power to make it happen. this is why car speakers are much less efficient than most pa speakers, impedance matching is part of this equation but save that for another post. people often talk about slow subs or fast subs, like that faster subs play kick drums better and slower subs are better for rap/hiphop music and actually that is all true, speed is frequency or rate of osculation and rock music tends to be based off of higher bass frequencies where EDM, Rap an d hiphop tend to operate at lower frequencies so slower subs or more correctly subs with lower resonant frequencies which play slower really do better for the low frequency bass typically 45hz and down. and typical rock which usually does not play below 45hz can use a faster subwoofer and excel in that range. now for the kick drum issue well that snap is often striking clear up into the 5-7khz range and if your system has a muddy kick drum sound its usually a phasing issue with the drivers not coupling across xover areas and not a slow subwoofer issue. Driver sensitivity does matter and plays a huge role in how things preform and if you understand what's going on its a parameter that matters. Car subs will always be less efficient than pa sub because of Hoffman's Iron law. next important thing to learn from this is that sadly the sensitivity spec provided with the T/S parameters is miss-informative or miss-leading. what is somewhat useful is a spectrum analysis graph and therefore a frequency sweep at the standard ground level 1w/1m. that paints a better picture, seeing as with out it you don't know where on the spectrum is that peak sensitivity occurring. with a graph you can see what the driver will do and the response is pretty linier as power increases excluding enclosure behaviors of course.
Thank you for this. The law helps explain my teenage sub setup in my head. The teenage setup was a 12" 94 dB sensitive 4 ohm sub that was in an oversized box and I loved the sound. Thinking about recreating a similar setup over 20 years later.
I’ve been a die hard bass head ever since I was 13-14 yrs old and I’m 37 yrs old now and your videos are really inquisitive and are extremely informative and i look forward to your uploads just to gain that much more insight I think that’s why I love this life style so much is that it’s constantly evolving and new products are always coming out and I’m down to do whatever it takes to squeeze the SPL teet to gain a dB or get that better sound quality and your videos help so thank you very much and keep that amazing content coming !!!
Great content! I think the last time I contemplated using sensitivity as a deciding factor on a purchase, was when I was buying some components to be ran off deck power in the wifeys car. Overall, it proved my theory correct of getting louder on Low power. Keep up the great content; it’s always a pleasure to see your brain in action.🧠🔈🔈
I appreciate your videos so much! All the time and knowledge you contribute to the field is invaluable. Tuesdays are one of my favorite days because of Tech Stuff and I look forward to it every week. It's nice to see someone (you) who puts forth EVIDENCE of things that most others just spout off about with no factual basis. Thanks for everything you do Sean!!!
First subwoofer you tested to me, sounds cleaner then the second sub in this test. Just confirms what I had in the past. Kicker round Comps. 12” 96dB moving 12.5 cubic feet per woofer.
So what your sayins is to not worry about sensitivity spec and buy a currently on sale banhammer or lowballer and make some noise!!!! But seriously... it's great that you are covering the actual rules to the games and not just " this is the new ish because its got blah blah blah". Keep up the good work sir!
most sensitivity tests are done with the mic in front of the cone, with the front and back waves separated with a baffle. LOTS of variables in this test left unaccounted for it to be conclusive proof that sensitivity doesn't matter.
I do see where you're coming from, as is the a reason for installing the sub in a baffle. That second 8 had the mic pointing almost directly at the basket mounting point.
I'm with you, the mic should be infront of the speaker, especially here when the subs are placed in the same place but they are different sized, resulting in the bigger subs being closer to the microphone. So there is one variable added here. Also non of these speakers probably play perfectly linear so that's why we see between the 10w and 20w less or more db, instead of exactly 3db. It's good information but we can't take it because of the added variables.
As I mentioned in the video, I won't argue, but I still state when they're all done the same way it doesn't matter, and if you watched the last half of the video they were all in enclosures, eliminating those factors with the same results.
If all other parameters were equal, and the only difference was sensitivity, what would the results show? This is less a disproving that sensitivity matters and more proving that other factors contribute to overall output.
Hey man love these tech Tuesday videos! These are so helpful in learning more about this great hobby! Do you think you could do one about building enclosures. Specifically focused around tuning your enclosure to the proper frequency for specific woofers??
I've had that requested before, the tricky part being I like to have visuals to explain so I'd have to have access to some things I don't have access to right this moment, like bandpass boxes.
EMF Audio cool! It would be a very helpful video in the future if you can swing it. Your good at explaining this Material. Most box building videos on the internet are not very clear when projecting useful info.
If you had to pick 2 8” subs from American bass HD, 6:03 VFL, SSA F8l or ampere audio rve 2.5 which would be best in your honest professional opinion? I love the channel by the way
Although I agree that sensitivity ratings are not as consistent as most of us have thought of, the main take away here is that higher sensitivity rating still gives you a better guide of the average effeciency of each sub. It still holds a merit that you will have a better chance of having a more efficient sub when the rate is higher although should not necessarily be counted as the only source of data.
When you're talking about a 4-5 dB difference in sensitivity and the lower rating being louder in reality, that proves it means nothing in any capacity. You can't pick and choose when it applies. If it shouldn't be the only source of data that proves it doesn't mean what you think it means. Science is factual or it isn't.
How would this effect if all subs you tested were new out the box? Think numbers be way different? Used subs had its chance to loosen up there for be easier to get more output/ volume over the new sub?
The problems I would encounter with that is I would have to be exactly 1 meter away and be able to precisely apply 1 watt, not 1.5, not 1.8, not 1.2, 1.0. The jig being setup, less critical, but the power would be an issue, which is why I mentioned the reason in doing the 3 higher power levels. Also, the numbers used aren't "manufacturer numbers", they were all taken using the same equipment just prior to the test so any play time was not a factor. None of the subs can be purchased as they sat, 4 were custom builds and 1 is a prototype with minor changes to production.
@@EMFAudio Yeah you're right, I first thought about doing it at 6 watts and then calculating down but that would be way too complicated and unreliable..
Maybe its because of the logarithmic philosophy of how an amount of decibel increases. Slight changes to the rating might not mean so much that it causes some inconsistensies in spl results. Maybe if the sub sensitiity would go beyond 88 to 90, we may see some significant data confirming the logarithmic law when dealing with db's.
Sensitivity is sensitivity, it doesn't change with power applied. Gains from power following the logarithm can show inconsistencies from other factors being introduced.
The most accurate way to test this would be two use two drivers that have roughly the same T/S parameters other than “sensitivity” and use them in the same enclosure and measured it with a Dayton Mic, or REW software or equivalent . Also ...these tests are best done outside at 1meter or in a controlled chamber with the mic at speaker cone level.
Hi Sean and thanks for the long waited video! One question: I got a bass horn design in Hornresp, and no matter what driver I put into the simulation, (after a little bit adjustment) I always get a pretty similar curve trend. the two drivers I played with the most were GroundZero 15 Xmax and GroundZero 18 SPL. While the 18SPL claims a 10dB advantage over the 15Xmax, they show nearly identical curves on the sim, with the 15Xmax performing 3dB louder at lower frequencies. I'd doubted the sim results until your video proved it right. The question being, do you recommend any of the two drivers mentioned above for a bass horn(tuned way low to 20's and maybe even 10's)? I personally like the 15Xmax because of its high mechanical capabilities, high input power and strong aluminum cone.
There are 3 big factors between those two subs that is probably why it's saying what it's saying. First, displacement. The 15 is less cone area but according to them (who is known to inflate specs, especially Xmax) has over double the Xmax. Depending on power applied, the 15 may have more actual displacement, and certainly may help on low end extension. Second, Qts. One is significantly lower than the other, which will lead to being more peaky (likely the reason behind the findings). Third, Fs. There is a good sized gap in Fs, especially down low. Coupled with the Qts that can have a large impact on it's ability to play lower, better. As I have also proven before though, those simulations might be completely wrong from reality.
What exactly do spiders do? You touched on this a little bit but can you elaborate a bit? If im going to underpower a sub am I better off with more or less spiders for spl? Thanks.
I did an earlier video on what all the parts do but the basics is it holds the coil where it's supposed to in the gap. There are extremes to your example but generally for under powering you may want less stiffness (notice I didn't say less spiders) to get a better result. If you go too loose you lose output though. It's a balance of stiffness and displacement.
This is silly: 1) You aren't measuring in freespace, and actually getting higher energy recordings than the sensitivity equations allow for BECAUSE THEY'RE SUPPOSED TO BE IN FREE SPACE = YOU'RE MEASURING REFLECTED SOUND 2) You can't use the same box for different drivers and call it fair. You need to match the FS/porting/whatever your enclosures parameters are to the driver and use a SIMILAR enclosure. 3) What you have proven is that a vehicle is a very inaccurate place to reproduce low frequency.
1) They're all tested in the same exact conditions against each other, that's what a proper test is. We were not testing for a test spec against a manufacturer rating. As long as the only variable is the driver, the test is valid. 2) How can the enclosure be similar if you're using the magical absolute specific box for each driver? Again, the proper way to test things is to have 1 variable. When you change the environment (enclosure) you change the results. 3) You're saying car audio products don't belong in a car. What you've completely missed from this entire video is the point. It's said that a higher sensitivity sub IS louder, no matter what, every time. You look at the specs, you pick the one with the highest sensitivity, it's louder. That's exactly what this video was showing is or is not the case. Testing in free air was to confirm against parameters as both are done in free air, then enclosure testing to validate against free air.
Yes awesome, do you rebuild them , I have 12 15s , they all still work but I imagine they are getting tired, probably need the magnets re-magnetized, they are 20 years old , new spiders , and maybe coils that can handle more power , I currently have 4 hcca 15s in a ported enclosure being driven by an Orion hcca 8k , I am afraid to give them full power cause of their age , if you do rebuilds let me know how I can get more information, thanks and great video again I try to watch them all
I rebuild all kinds of things. Magnets generally don't lose magnetism unless they're exposed to extreme heat. Spiders and surrounds can definitely get wore out though. I think you'll like tomorrow's video.
I get argumentative people telling me all the time that the only thing that matters is "POWER" as they're running 8k-10k full bridge amps and cooking their subs. I belive that there's more to a system than just power and I include the fs, rms, sensitivity, hz range, BL factor, mmd specs, cone area and xmax. Then take into consideration the amp specs and quality and the box specs and quality all for what I'm trying to do. Personally I don't go around bumping test tones while I drive so to me power isn't everything nether is having my box as loud as possible at a tiny frequency window lol
Yeah sometimes. I have a pair of Boston Acoustics 10.4LF's. Sensitivity is "typically" measured at 1 watt/1 meter. For some reason... They measured the 10.4LF at 1 watt/1 foot or something like that. Made the sensitivity number look good coming in at 96.2 db if I remember correctly. You'd see that number and if you didn't know the typical standard, you'd think it was a louder sub. Great sub in spite of the way they measured it. I have a pair myself and if you want SQ Boston Acoustics (at least their older stuff) is worth the look. I love those subs.
Are you seeing how higher the sens rating the higher frequency it could play (higher inductance frequency), higher sens having higher FH in other words higher frequency roll off, and a sharper/steeper low end roll off!
It all depends on what frequency you want to play. More and or stiffer spiders equal less output in lower notes, but higher in the higher notes. Basically only good for SPL range. At least in my opinion I don't buy a 12 inch sub to play 70hz lol.
You are correct, but the sensitivity number is regarded as efficiency, meaning it IS definitively louder. Yes it might be more efficient but only in a specific bandwidth that might not be what you're using it for.
All I am really saying is when you start putting extra and/or super stiff spiders on a sub to keep it from bottoming out, then you are pushing higher power to move the sub..... I mean I would upgrade from a 4 cylinder to a V8 car just to ride the brakes constantly while accelerating. The whole point for a subwoofer is to move up and down, not just be a big heat sink to brag about how much power they handle without catching on fire.
If you're putting more or stiffer spiders on a sub to keep it from bottoming out, you should stop building subs and stop installing. What you're saying is every sub should be floppy so you can do 160's on 200 watts. There is WAY more to it than just moving up and down. A properly designed sub adjusts many aspects to fit a power handling, you don't start from a spider stiffness.
Lower sensitivity= more power to make same DB if I'm not mistaken. But also low watt subs have higher BD and high watt subs have lower DB. But say 90 db 200 watt sub and 80 db 1000 watt sub... which would have higher output in a sealed enclosure that takes the same spec size box? Same speaker size too
@@EMFAudio I did... maybe I didn't properly convey my question. I'm not a fucking scientist like you assholes.... maybe you should learn a little humility and respect before commenting instead of not!
I don't think you're following what I'm asking. A speaker is not just loud or not. The application of where it's being used determines that. What's loud on a meter at a high frequency won't be loud at low frequencies to the ear. What is loud in one box won't be loud in another box. You have to know the conditions of use before being able to make any determining factors on a sub.
@@EMFAudio sooo, my use case would be 25 to 35 hz doors open, playing to a crowd brazillian style. but, not high punchy pa bass. lowsssssssss, like dj rustical rebassed and slowed. when i buy speakers, firstly i check through the data sheet to check bl and the freq response graph to see where the speaker is happy at, and use that to short list. and then, i go in and demo the short list to hear how they perform, against each other. i was wondering, if there if there are parameters to watch on the spec sheet, to determine which sub MIGHT be better at certain freqs, than others, if u put them in the same tuned enclosure.
I would rather use 1 watt-1 meter, rather than 2.83 volts, because 2.83 volts means you will pass 4 times more wattage into a 2 Ohm driver, than into an 8 Ohm driver.(as if it matters) The only thing the sensitivity rating might be relevant, is if you're listening to elevator music... in an elevator! That's about the only time I would expect a driver to be run at 1 watt or less. In a car, with all the road rumble, and the fact that we are talking about subwoofers, I don't think you would even hear anything less than about 40 watts. Our subwoofer system has a separate volume control for the sub. The curious thing is, that when going down the road, it almost seems like it isn't even working until we increase the level about 12 db. If we don't touch anything, and park the car with the engine off, we play it again,(same song, same settings) the bass is all you hear. We knock that 12 db off again, and it sounds "balanced" again. This just exactly verifies your point, in a real car, (Chevy Suburban), going down a real road, "cranking real tunes".
Your example about driving vs parked would make for a GREAT video, if I found a vehicle worthy (or timing) for doing such a video. All of mine I couldn't do a before and after explanation.
sensitivity matters in different types of drivers imho youre testing this on subs where it doesnt matter much. shoulda added something like an old stroker or old soundstream spl160 or maybe an acoustic elegance driver in the mix and i bet youd see that with those style of drivers it matters quite a bit more than it does with the style of drivers common nowadays. its kind of a mass vs compliance controlled issue it matters more for one style than the other.
The same result will happen, it's science. Even when you compare mids there is the point to be made that in many cases the louder speaker doesn't sound as good.
Can you make a video to let us know how to choose one subwoofer over another based off of performance and not a brand name? I understand that sensitivity isn't a factor, but what figure is most important for us "Shade Tree Audio" guys to look at?
@@kidsavage86 It could. Opening up the rear deck would help if you can. DO NOT just cut the whole thing out, but removing rear speakers will help as a starting point if you have them there to remove.
@@EMFAudio do u guyz make boxes like a 4th order ported into the car custom specs ill buy if so in eny they want 900 bucks for a box alone n i own the subs and amp already
@@kidsavage86 There is a reason they want $900 for that box. There is a lot of material and it takes a ton of time to do that. We don't do customer boxes. I don't have the time and I refuse to ship one. Some giant contraption like that would be impossible to do on anything less than a pallet which would cost a few hundred bucks in shipping.
given a set amount of power, the higher sensitivity woofer tends to be louder. if you're running a low power setup, and want the most bang for your buck, you'll generally want a higher sensitivity driver.
@@EMFAudio so is sensitivity the same as efficiency? If I have a 600w RMS woofer with 92 db 1w/1m sensitivity vs a 2400w RMS woofer with an 86db sensitivity, wouldn't it stand to reason that the 600w woofer will be louder up to its mechanic limits, where at that point the 2400w woofer would continue to get louder. That's all I'm saying
@@wadehensley5005 What I'm saying is watch the video. The results were basically the same at all 3 power levels in free air indicating that doesn't matter. Yes mechanical limits are another story but the argument is definitively higher number is that much louder, always, at any power.
sensitivity matters for spl but if u want the ultra low shakes with low frequency only big bulky highly not sensitive subs mainly due to materials used with massive power to boot can achieve this. I have 2 x lms18 5400 ultras that eat 3.5 each np with no sweat and 2 x 18 bms pa drivers filling in the rest quite comfortably running at 250watts. with everything is compromise and scale. The BMS can out out same SPL as the ultras. Even with the power difference. But it's at what frequency and with any ported enclosure is a tradeoff for speed and accuracy. Sealed is and always will be the most accurate soundstage.
It would neat to see a comparison A car audio subwoofer vs Pro Audio subwoofer at 30 meters away "98 Feet" same wattage same size subwoofer 18" or 21" I have a pair of PA subwoofers in my house they are loud as can be in a big room. My Kove Armageddon's 15's don't feel as loud as my PA speakers do with 4X the wattage. Hell the loudest cars back in the 1990's use a PA subwoofer called the Cerwin Vega Stroker. Originally meant for the movie back in the 1970's called earthquake. It's a theater subwoofer that needed a gigantic box in the realm of 12 to 14 cubic foot box for each 18" I like pro audio subwoofers they just have that hard hitting bass drum effect to them. I never heard a car audio subwoofer ever do that! When I play rock thru my car subwoofer's it sucks My JL Audio 15W4's are crap, "sealed enclosure" Earthquake 15's Sealed Enclosure" Crap, Kove Audio Armageddon Z series 15's "ported enclosure tuned to 32 hz" Crap Atomic Audio "sealed enclosre" Crap I said screw it and bought some PA subwoofer drivers for my truck ported it tuned to 29 hz it freaking kicks some major butt with rock/metal music does okay with rap and R&B too. "long bass notes" I should post a video of PA speakers hitting low notes in a vehicle.
I mentioned in the video with the 8's, the 80 dB sub is louder than the 83 dB sub with more power on it. I've made several subs where that spec wasn't actually louder.
@@2010HarleyDynaFXD You are correct in saying that you don't get a hard hitting drum beat with the car audio drivers. They are not designed for that. They are designed for ultra low frequency and for that requires large amounts of excursion and very high power. PA drivers are a lot more musical and don't push no where near as much air but the tradeoff is no ground shaking lows. My system is designed for hi fidelity music listening in a big room. The car subs are best with a sealed enclosure for accuracy and punch low down. Yes some spl is lost but theres always a compromise. To cover the range completely I use 2 x18 pa drivers in the speaker enclosure coupled with 2 x 18 car audio subs sealed. The results are amazing to say the least. Sounds I have never heard before its crazy.... Get both ftw.
@@EMFAudio The sensitivity is measured at 1 watt. Upon delivering several times that it very well be that things change. Upon my experience lower sensitivity drivers require a lot more power for the same spl but as in my case it scales so if I feed enough power (3500 watts into 4ohms in my case) then these easily push more spl than the higher sensitivity driver but far more power is required.... Higher sensitivity drives are generally not designed to push as much air as lower ones. Sensitivity depends on the make up of the sub and materials. lighter materials, less spiders etc is higher sensitivity. Lower sensitivity is heavier materials as in my case a super rigid suspension, thick rubber surround and titanium cone. The difference here is all about how much more power is needed for lower sensitivity but this will also dig deeper than than the higher sensitivity...Tradeoffs..
no it isnt. xmax is only potential output. SD and efficiency are more important parameters to look at if you're not building a 80k watt air pump spl box on wheels.
I agree, since I like sealed boxes. Since you don't have the phase shift of a port to phase with the front of the cone, you need more excursion to get the same output from the same size driver. I just ordered a "Lowballer" 12, to replace the original driver in a subwoofer used for home theater. I'm blocking the port, and just feeding the driver more power, but I needed the extra cone excursion, to extend the lows from 30 Hz down to (hopefully) below 20 Hz. I have to seal the box, because that would be too far below the tuned frequency of the port. To maintain loudness, you need to double cone excursion for each octave you go down.(cutting the frequency in half) At the super low frequencies, there's "no replacement for displacement".
Say you have a power limitation. Like in my hybrid vehicle. More than about 600w is not an option. So a higher sensitivity sub rated at the same power is going to be beneficial to my application
I always wanted to see an EV stereo build that used aluminum honeycomb panels for the sub and efficient speakers and amps. It always seemed like a fascinating project to me.
I find it more hilarious that people cant recognize apples to apples comparison to get information that let's you know you might be over thinking certain specs
I'm not sure how you get to that conclusion. In any case of any age saying this or that is louder than this or that will depend on the application. Generally speaking, newer equipment is louder and sounds better.
@@ruikazane5123 You just referenced what this video proves invalid and no, they DIDN'T play lows like subs today. "Low" bass then was 35 hz. I have "bass music" from that era that mostly plays 45 hz and up.
No No No ... This i s all wrong ! Sensitivity says what kind of sub it is . For SPL you would want a pissed off sub that will scream loud ! And for blues , maybe a sad one.. :P
This test has so many flaws lol . Sensitivy does matter . Not as the ONLY parameter to look at , but it does for effeciency aspect... if you put the Same size driver with the same T/S paramenters(VAS, Xmax, QTS) in the Same Enclosure and (same port etc.) and the only difference was their Sensitivity , the higher sensitivity would be louder . Its basic speaker physics.
Did you take into account how much current ?. 30 watts could be 12 volts, 240 volts massive difference. 1 amp to 10 amp massive difference. Did u take into account the current draw from the amplifier ? because amps are important than watts. If your reading says 30 watts at 1amp or ac voltage amp the difference can be 10 fold. You don't measure current which is essential lol
This is totally incorrect. Yes, current is what matters, but because of Ohm's law, if you know any two of power, current, voltage, or resistance, you can find the other two. They're multicolinear. Two speakers with equal sensitivity will be equally loud in their pass band at one watt, whether it's 1 amp and 1 volt or one kA and one millivolt. Sensitivity is based on power, which is what he's comparing.
As mentioned, Ohms law is why that doesn't matter. The amperage will be dictated by the impedance, that doesn't matter because I'm testing the same wattage to the same wattage. So if I wanted to do it completely wrong I'd be measuring amperage. There is a reason power classes go off of watts and not amps.
@@kenhaze5230 speakers are rated as nominal impedance. Kef reference 205 for example has an 8 ohm impedance but will lower to 3.2 ohm under certain loads. if the amp cannot drive such low impedance there you have the problem. That's why many people have high current amps to power those speakers. High power subs require even higher current.
Actually, all the specs exist because you can tell a lot about how it will act in an enclosure, when viewed as a whole. You can't focus and make decisions on 1 spec alone. The RMS rating is actually more pointless than the other specs in the car audio world as there is no standard for rating them. RMS ratings are a number listed by the manufacturer using whatever method they chose, be it actual testing, or marketing, or something else.
