06RTCharger Posted August 30, 2017 Report Share Posted August 30, 2017 If i have a mid bass with a an fs parameter of 41.5 (free air), would it being in a sealed door raise or lower that at all? Or is the inner door cavity large enough to be considered free air? Reason i ask is im trying to figure out how low i will be able to tune my midbass crossover. After i find that out i can think about how high i want my subs crossover. Im thinking 55hz for the subs crossover, and 50hz for the midbass. Trying to avoid being able to hear the bass coming from the back of the car. Around 55hz should be a very omnidirectional freq right? With a midbass fs of 41.5, i should be able to safely set the xover at 50hz right? Link to comment Share on other sites More sharing options...
fmedina Posted August 30, 2017 Report Share Posted August 30, 2017 idk if this post will be a help in finding your answer. as what i understand, fs is the free air resonant frequency. so the frequency that is most audible from the characteristics of that sub/speaker. (please correct me if im wrong anyone) so now if wanting to change and/or "amplify" the frequency thats where a tuned enclosure come into play. so if i understand correctly, maybe seal up a portion of that door to encase the speaker properly and stick a small tuned port in there somewhere lol Link to comment Share on other sites More sharing options...
ShadeTreeMechanic Posted August 30, 2017 Report Share Posted August 30, 2017 The fs parameter is the resonant frequency of the driver in free air. Free air as in no baffle sitting on the table. Put it in a baffle and the resonant frequency changes. It is a little misleading. The only thing it is really used for is to calculate the 3db down point for the enclosures low end response curve. My mids have an fs of 100hz and I cross them over at 60hz no problem. The real way to set it up is to use an RTA and adjust both up and down until you have your image solidly up front with no peak or dip where they transition from sub to mid. 91 C350 Centurion conversion ( Four Door One Ton Bronco) 250A Alternator (Second Alternator Coming Soon) G65 AGM Up Front / Two G31 AGM in Back Pioneer 80PRS CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon) Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon) Link to comment Share on other sites More sharing options...
06RTCharger Posted August 31, 2017 Author Report Share Posted August 31, 2017 3 hours ago, ShadeTreeMechanic said: The fs parameter is the resonant frequency of the driver in free air. Free air as in no baffle sitting on the table. Put it in a baffle and the resonant frequency changes. It is a little misleading. The only thing it is really used for is to calculate the 3db down point for the enclosures low end response curve. My mids have an fs of 100hz and I cross them over at 60hz no problem. The real way to set it up is to use an RTA and adjust both up and down until you have your image solidly up front with no peak or dip where they transition from sub to mid. Ohh ok, i was thinking free air was like IB lol noob. So in my situation where my 8's fs is 41.5, having it in my doors sealed up decent and tuning them to as low as around 50hz would be fine? I wonder since u went way below ur fs....how low these could be tuned, 30hz lol? Just to be clear, isnt it dangerous to tune below fs? Is that considered going past the drivers ability to control the cone? Or is that something totally different? Link to comment Share on other sites More sharing options...
06RTCharger Posted August 31, 2017 Author Report Share Posted August 31, 2017 On 8/29/2017 at 4:11 PM, fmedina said: idk if this post will be a help in finding your answer. as what i understand, fs is the free air resonant frequency. so the frequency that is most audible from the characteristics of that sub/speaker. (please correct me if im wrong anyone) so now if wanting to change and/or "amplify" the frequency thats where a tuned enclosure come into play. so if i understand correctly, maybe seal up a portion of that door to encase the speaker properly and stick a small tuned port in there somewhere lol Lol that's a cool idea, just stick a lil aero port or something into the door. I wonder if anyone has ported doors. Link to comment Share on other sites More sharing options...
fmedina Posted August 31, 2017 Report Share Posted August 31, 2017 29 minutes ago, 06RTCharger said: Lol that's a cool idea, just stick a lil aero port or something into the door. I wonder if anyone has ported doors. ya ive seen some builds with ported doors. cant remember exactly which ones but theyre out there Link to comment Share on other sites More sharing options...
ShadeTreeMechanic Posted August 31, 2017 Report Share Posted August 31, 2017 7 hours ago, 06RTCharger said: Ohh ok, i was thinking free air was like IB lol noob. So in my situation where my 8's fs is 41.5, having it in my doors sealed up decent and tuning them to as low as around 50hz would be fine? I wonder since u went way below ur fs....how low these could be tuned, 30hz lol? Just to be clear, isnt it dangerous to tune below fs? Is that considered going past the drivers ability to control the cone? Or is that something totally different? The lower crossover point would be used to keep the driver from trying to play notes that might cause trouble for it or damage it. I believe that the enclosure has more to do with cone control than the build of the driver. In a ported box, the tuning frequency of the port determines how low the driver can play with good cone control. Problems happen when the driver is played below tuning. Then it is up to the suspension and sometimes it is not enough. Add more power and the problems get even worse. Its hard to say how low your speakers can play without having problems because every install is different. It is just something you will have to experiment with. I would recommend starting out around 150hz while allowing them to break in. Every week or so turn the crossover down a little and after about 6 months or so you should be around where it wants to be. My Strato Pro comps are finally at this point where the can take more and more power before they complain. I bang on them every day. 91 C350 Centurion conversion ( Four Door One Ton Bronco) 250A Alternator (Second Alternator Coming Soon) G65 AGM Up Front / Two G31 AGM in Back Pioneer 80PRS CT Sounds AT125.2 / CT Sounds 6.5 Strato Pro component Front Stage CT Sounds AT125.2 / Lanzar Pro 8" coax w/compression horn tweeter Rear Fill FSD 5000D 1/2 ohm (SoundQubed 7k Coming Soon) Two HDS315 Four Qubes Each 34hz (Two HDC3.118 and New Box Coming Soon) Link to comment Share on other sites More sharing options...
06RTCharger Posted August 31, 2017 Author Report Share Posted August 31, 2017 Alright ill try to remember that. Makes sense to have the spiders fully broken in before u know its limits. Thanks again man. Link to comment Share on other sites More sharing options...
fmedina Posted August 31, 2017 Report Share Posted August 31, 2017 Break in? Fuck it just bump them! Lol jk good luck bro Link to comment Share on other sites More sharing options...
06RTCharger Posted September 1, 2017 Author Report Share Posted September 1, 2017 14 hours ago, fmedina said: Break in? Fuck it just bump them! Lol jk good luck bro FUREAL! you dont know how bad i want to hear my system already lol it been probably over a year of collecting my equipment piece by piece. Still aint even done yet, SUPER close tho. Just one more bass amp to go, and then decide on what power supply to go with. Just a 79.8AH Lithium or xs d4900batt + xs sb1000 caps. After that i can finally focus on just putting it all together and fabricating everything. Link to comment Share on other sites More sharing options...
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