sundownz Posted December 30, 2010 Report Share Posted December 30, 2010 After getting several e-mails and calls about Sensitivity of subwoofers and seeing quite a bit of forum action regarding sensitivity I've decided to post this up... Sensitivity does not = Efficiency on a subwoofer on LOW bass. This is regarding industry standard sensitivity measured at 1khz -- this is where the spec is measure on 99.9% of speakers in the world. Hoffman's Iron Law dictates that out of sensitivity, small box size, and low-end extension you can pick two and the other suffers. In car audio, especially, you want small box and good low-end so sensitivity will typically be lower than a home audio woofer -- where you can use a large box and then have both high sensitivity and good low-end. Since we have done quite a bit of SA-8 testing recently I'll use it as an example for the rest of the discussion. Some recent SA-8 testing results to demonstrate this... measured in Sean's CRX in a box tuned in the mid 30s: SA-8 / CCAW Coil (83.42 dB 1w/1m) D2 : Frequency / Power / SPL 25 - 430 - 123.9 30 - 400 - 127.4 35 - 300 - 129.0 40 - 210 - 129.6 45 - 120 - 128.7 50 - 90 - 128.5 SA-8 / Copper Coil Stock (78.6 dB 1w/1m) D2 : 25 - 470 - 125.0 30 - 240 - 131.1 35 - 140 - 132.9 40 - 100 - 132.6 45 - 170 - 130.7 50 - 270 - 129.3 Take note low-bass fans... at 30 Hz the copper driver with nearly 5 dB less sensitivity is using 60% of the power and is 3.7 dB louder. So... which one is more EFFICIENT on sub-bass by the real definition... output per watt. The CCAW coil doesn't pull ahead in real efficiency until out of the really low sub-bass region @ 50 Hz. So... sensitivity should at least pan out in maximum SPL, right ? We put in the SPL box tuned very high and still... not as much effect as you might imagine... the CCAW coil achieved 151.0 dB @ 1310 watts and the copper 149.9 dB @ 1600 watts -- not nearly as much as one would imagine by the 5 dB sensitivity different, huh ? Even at lower power... both drivers at 250-watts we have 144.9 on the CCAW and 143.3 on the Copper -- just 1.4 dB down at 68 Hz... for a HUGE gain down low. Is the higher sensitivity driver a better choice for peak SPL ? Yep -- that extra 1.5 dB will win the show... but is it worth a nearly 5 dB loss at 30 Hz (adjusted for power difference the actual loss is about 5dB) for a daily system ? In the minds of most car audio enthusiasts that would be a HUGE "NO SIR!" ----- This testing was done in-house for my own purposes of product development and not to simply prove a point... but since the point needs to be made I have decided to share it. Product design is a balancing act... with an 8" woofer on a standard diameter spider landing you need a certain amount of stiffness to hold up to what people do to drivers in the real world. On a driver like the SA-8 by the time you get to that level of stiffness a bit of additional mass is needed to drop the FS to a reasonable level so we used a copper coil to get there. Can I soften up the CCAW driver spider a bit and help the low-end ? Sure can -- and we'll be testing that too. The sacrifice is you end up with a less mechanically rugged driver that, in terms of VAS, wants a bigger box while at the same time the bigger box further compromises mechanical power handling. In terms of the SA-8 we are working on different spider tools and so forth to try and get around some of these things. So far the combination we have is the most effective for what most people need / want. If we end up being able to improve on it without sacrificing durability then a v.2 SA-8 will be born. Quote - Jacob Fuller - Owner, Sundown Audio - Sundown Audio on FACEBOOK - Please DO NOT PM ME -- use my email address -- [email protected] Link to comment Share on other sites More sharing options...
OrionStang Posted December 30, 2010 Report Share Posted December 30, 2010 Nice info. I've wondered about this at times. Quote SMD Super Seller My Feedback Thread Link to comment Share on other sites More sharing options...
TheBetterMethod Posted December 30, 2010 Report Share Posted December 30, 2010 Great info! I'm ready to see the new SA-8. Quote 2005 Subaru Outback Wagon Pioneer 9400BH Fi Q 15, SAZ1500dV3 The first build>>> http://www.stevemead...-outback-build/ 140.9 @ 36hz Sealed on dash! REBUILT!!! 2 Fi Q 15s, 2 SAZ1500dv3 146.9 @ 39hz dBDRA certified Link to comment Share on other sites More sharing options...
LT.Smoke Posted December 30, 2010 Report Share Posted December 30, 2010 Thanks for that information Jacob it was very helpful in letting me understand more clearly about how sensitivity works Quote Team MaxRetribution Si Vis Pacem Parabellum Id rather be judged by 12 than carried by 6 Bowhunting- Life Begins and Ends at Full Draw Bowhunting Team Fatal Trajectory Hunt Team http://www.stevemeadedesigns.com/board/topic/49335-sick96vtecaccords-t-line-build/?hl=sick96vtecaccord << Accord Build http://www.stevemeadedesigns.com/board/topic/68498-smokedout08impalas-tline-build/?hl=+sick96vtecaccord << Impala T-line build Rebassed.com for all your music needs 👌 Link to comment Share on other sites More sharing options...
meade916 Posted December 30, 2010 Report Share Posted December 30, 2010 a good read.......nice one Jacob Quote All SMD products + MORE available at my store here! https://wccaraudio.com/ Subscribe to My Youtube Channel! Over 1,000,000 subscribers strong! Turn on your notifications! http://www.youtube.com/meade916 Follow My Instagram! Daily live feeds from the shop, exclusive content way before it hits my Youtube channel...and little squares with photo's in them http://www.instagram.com/meade916 The Official SMD Facebook fan Page https://www.facebook.com/SteveMeadeDesigns/ Follow my Tweet (Twitter) http://www.Twitter.com/meade916 Link to comment Share on other sites More sharing options...
kirill007 Posted December 30, 2010 Report Share Posted December 30, 2010 (edited) Finally a thread about it from a company, now i can show this link to people EDIT: Finkster what u mean? I didn't see anything that looked hard to comprehend. :s Edited December 30, 2010 by kirill007 Quote Thinking is the root of all problems... You ALWAYS get what you pay for. Link to comment Share on other sites More sharing options...
finkster Posted December 30, 2010 Report Share Posted December 30, 2010 This is probably more of a take notes session than a discussion, as there's probably only a handful of people on the site that know wtf all of this just meant, truly Quote DAT 4125------>RE XXX comps active Eclipse cd7000 I serve drunks for a living Link to comment Share on other sites More sharing options...
VOPA Posted January 5, 2011 Report Share Posted January 5, 2011 So, can we attribute the performance difference to the difference in MMS? Quote 04 Monochrome LT Chevy Tahoe -A few wires, half a speaker, some watts -All Black 6's -Paint to Match, SS Bumper, Black grills. -HID'ed and LED'ed -A few performance enhancers I have two nice subs for sale, but I am not allowed to help my fellow forum members by offering it to them for a nice price via my signature, sorry Link to comment Share on other sites More sharing options...
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