Advanced Discussion

I want to make sure I calculate this correctly because apparently i am slightly off, either that or other manufacturers are off. When calculating port length, let's say it says to use 26" long and you are, for example, using 12.56sq in of port which is for a 4" diameter port. Radius is 2" I thought to calculate slot port length was to take the 26" depth and subtract from that the sqin radius by converting the sqin value to a circle then finding the radius, which in this case is 2". That would then make the length 24" but when looking at manufacturer's giving you specs like a baby, either their calculations are wrong or i have been told wrong! So, what do i need to know to…

Hey all , I've got this AA mayhem 15 inch dual 2 ohms wired to 1 ohm , now BBpro6 tells me that the minimum impedance under load will be 2,05 ohms in the box its playing in , is this what the amp will see or will the amp still see the Re of 0,7 ? thanks in advance .

Hey guys, just wondering what your input was about passive radiator boxes used in car set-ups??? I used to have a set-up of 2 12" VMax(the red older surround version) with 2 AE speaker 1050g PR's and its lows were pretty amazing. However, I had to have a pretty large box to utilize them like I did. Are there any advantages to me trying to use these PR's in say a SQ set-up or are there better alternatives out there? Let me know what your thoughts are! thanks

I have been building boxes for sometime and I notice that a lot of boxes have the same concept but are built a little different. When I build a ported box for two subs I normally direct the air out of the front (depending on the application) of the enclosure with a divider between both chambers. I have seen some enclosures with no divider coming out of the front, just a big hole. Does adding or taking away a divider give off a different sound? I also add one in the middle just to make the box more rigid. I am building two ported boxes for a van. Would it be better to port it in the front like I have been doing or to go another way. I would think that by porting it out the…

2007 Honda Accord Pioneer 80PRS Sundown SAZ1500 Fully Loaded 12in FI BL 2.5 cu ft box after displacement tuned to 34 hz All 0g wire and Shruiken 1500 extra batt plus yellowtop up front The FS of the sub is 39.8 and i was wondering if there was any relationship between fs and box tuning? My main goal is SPL but I will use it as a daily driver so i dont want the sound quality to go to shit.

So, what is the cause of "moving air"? There are two possibilities in my mind that I think would create this. #1. Air Displacement from the motion of the moving cone of the subwoofer. #2. Actual pressure (sound waves) moving the air inside of the car. In scenario #1 the key to moving the most air would be to have the most cone area, the most excursion of the subwoofers and to have a sealed box (ports have an opening in them so technically a port would help the equalization of air pressure inside of the car) This would also explain why Randy Kubek pretty much has a mobile wind tunnel because he has always ran sealed boxes. ( for reference) In scenario#2, there is much …

hey guys i have a quick question. what is the benifit of tuning your box closer to the res. freq of the car instead of to the sub? in spl competitions?

Hi everyone, new guy here. I'm a mechanical engineering student/intern at the moment and have had a passion in audio for nearly a decade now. I took it upon myself to design an enclosure for a pair of Demon 10"s for my civic hatch. I'm pretty happy with the punchiness, but the lower end is lacking pretty significantly and sounds "blown out" or "not really there" instead of "deep". I'm hoping to get some insight on where I went wrong with my design. As you can see, this is a non-traditional enclosure where the port effectively shares 4 walls with the enclosure on the outer sides. The design was done this way to maintain a specific outer dimension that fits like a glove in …

I guess I'm being really optmistic here, but are there any pieces of software (free, would be nice ) that accurately model horn-loaded speakers in room? I'm trying to model efficiency gains from different types of enclosures, and most modeling software comes painfully short... All the research I've done on horns doesn't give actual numbers for efficiency gains; of course, most of that is room/placement dependent, but some general guidelines would be nice to go on...

Hey guys. I used to have a nifty little excel sheet based off of JL's equation, but my computer died and poof went that. Does ANYONE have this document? The original was removed by the poster. Please help me out here guys. That thing was the key to me making any enclosure. Thanks!

I've noticed that a lot of people suffer from the same misconceptions about the same topics in the world of car audio. This seems a befitting place to dispell those myths. Amplifiers Amplifiers do not magically create power. They simply convert existing power from your car's electrical system (amperage and voltage) to amplify a source feed (usually RCA or Line Level input). Just because your amplifier says it puts out "1000w RMS" doesn't always mean that your electrical system will put out enough power to actually achieve this rated power. In fact, 9 times out of 10, it won't. Even if your electrical system will support the amplifier's needs, it isn't constantly putting o…

I have a pair of 8 ohm MJ18s. I am designing a Zobel for them at the moment and cannot find the published Le of these anywhere. I also don't have access to my Suncor LCR meter at the moment.... Does anyone know off-hand what it is?

I'm confused as to how a subwoofer can have a Resonant Frequency of say 18 hz, but a frequency response that only goes down to 25 hz. If the sub only responds to 25 hz, how can you know the fs is lower than that. The new Soundstream T5's are an example of this. I just don't understand. -C

My HU it a JVC AVX830. I have the option to change the q on my lows and mids in the eq. Now I've noticed when I change the q to a lower setting the speakers seem to play "louder". What does this do? Is this based off the qts of the driver? How should it be adjusted. Right now I can't seem to get the tuning right. It either sounds hollow and muffled or the highs drown out the words. Could someone enlighten me?

I actually have a few questions. I have two different box ides. If I build a box with the sub facing UP, and fire the port into the car, will i lose spl? And as well, if i build a box with the Sub facing UP, and the port facing up, will I have a greater, or same as the bass response from firing the sub to the rear of the trunk. In other words, will facing the port in a different direction then the sub, affect the spl factor of the sub.

Feel free to post links on how to fiberglass.....stay on topic please....below are a compilation from various members from caraudio.com http://web.njit.edu/%7Ecas1383/proj/main/ http://www.sounddomain.com/id/the1wagsjlguy http://chris.pfharlock.com/glass/ http://www.caraudioresources.net/technical.html http://www.sounddomain.com/member_p...?page_id=338498 http://www.sounddomain.com/id/jeep98 http://web.njit.edu/~cas1383/glassing/ http://www.geocities.com/stevebang2000/car-audio.html http://www.eatel.net/~amptech/elecdisc/fibrglas.htm http://www.sounddomain.com/id/goddyd4me http://www.carsound.com/cgi-bin/ubb...int=;DaysPrune= http://chris.pfharlock.com/glass/ http://www…

So Ive been looking at numbers, maybe im way off. its .078ohms/1000ft ohms/1ft ------------ 12v 14v------------ 12v Amps--- 14v Amps 1-/0 0.00078 ------------ 12v 14v------------ 15384.61538--- 17948.71795------------ 205.1282051 205A is at 75ft which is close to 250likemost charts say with the 1ft values are high as hell though. This looks more reasonable. 1/-0 ------------ Ohms ------------ ------------ Amps 350A ------------ 12-- 14 ------------ ------------ 12-- 14 50ft ------------ 0.034285714---- 0.04 ------------ 350-- 350 25ft ------------ 0.017142857---- 0.02 ------------ 700-- 700 12.5f…

I dont compete. My last 3 systems were with the port on the right hand side. But I like the design of the center port and it will also help with loading issues. Will it sound different with the port being in the center since im used to it being on the right. These are the 2 im looking at heres one heres the one i really liked

Well since ascendant has slashed the price on the Assasin more than likely assasins will be in my GF's moms truck and my GF's car. For my GF's car if a wicked one just wont work the way i want it to this is my idea...Transmisison line in a false floor. I have a few questions though, Would it be a good idea to put the speakers (probably two assasin 10's) 1/3 down the line to eliminate harmonics from the transmission line? Ive read death stories about improperly designed transmission lines ending up sounding more like organs than SQ enclsoures because of harmonics . Also, Does anyone know of a formula for how much X ammount of stuffing will dampen the sound of speed X a…

In ported enclosure, if you were to use PVC or Aero ports of different sizes tuned to different fequencies what would be the end result? Would the tuning frequency of the box be based off of the total port area or how would that exacly work? J

looking for a box design to fit behind seat of s10 that is the right cubic feet for a sundown sa8 top of box can be 5 inches deep and bottom can be 7 inches deep anyone got any designs ?looking for sealed

I was thinking about speaker and amplifier resistence with all these RMS threads and Iron laws going around........I remember once checking the ohms of my driver which was a dual 2 ohm driver.......it was 2.12 ohm in the box and 1.97 out of the box...........when the sub was hooked up to the amp (amp shut off and no music) the resistence was like 2.75 or 3 ohms............why would this be? J

My buddy recently bought a 94 Cadillac Seville, and the radio wiring was so ghetto rigged so he went to rewire everything. While wiring, something shorted and now his instrument cluster will not work at all. We pulled the dash apart and tested the power leads and the would get power right before the fuse blew and all the accessories worked fine without issues. So we figured theres a short in the factory wiring. We bypassed all the factory wiring and and gave it constant power right off the ignition and fused it the same as the factory fuse size. Still blowin fuses. The problems arose when messing with the factory radio. The radio would cut out at medium volumes. We took a…

Hey everyone, I posted a thread a while ago about trying to work out the ports for an enclosure for my sub. I've spent alot of time deciding whether or not to go with a ported or sealed enclosure. I've decided to go for a sealed enclosure instead. I've been using Bass Box Pro to try and design an enclosure and I'm getting a bit frustrated Here are the specs of the sub: 15” Electrical Q Value -Qes: 0.58 Mechanical Q Value -Qms: 3.62 Total Speaker Q Value -Qts: 0.501 Free Air Resonance -Fs: 19.10 Hz Equivalent Compliance -Vas: 207.0 liters One-Way, Linear Excursion -Xmax: 54 mm Efficiency -SPL 1W/1m: 85.81 dB SPL Effective Piston Area -Sd: 810 cm^2 DC Resistance -Re: 4.2 o…

So i've been searching a few different places, but I don't THINK im finding the answer I need ... The question is this(I've been pondering about it for a while) ... If you have a mono channel amplifer, and have 2 DVC subwoofers(wired how you need) .. how much does the amplifier send to each woofer? how do you go about figuring this out? If you have 2 subwoofers rated for 500RMS and a MONO Amplifier for 1000 watts RMS, how do you know each sub is getting 500 watts ? How does the amplifier split up the power(I guess)?