Advanced Discussion

Maybe this should be stickied... Impedance cannot be measured with a DMM. Only DCR can be measured with a single DMM, and this isn't impedance. There is no such thing as "Impedance Rise". There is an impedance curve, but this both rises and falls..... The system impedance will always be higher than the DCR of the driver under any condition. Many factors affect impedance, the biggest being the enclosure. Until you measure your complete alignment at all frequencies in it's operating range, you have no idea what the impedance is. Impedance changes do not change driver power handling, they change how much current you amplifier puts out at a given voltage.. Nobody owns a .7 …

Hey guys I remember years back, when we wanted to build a "premium" subwoofer enclosure we would use birch plywood rather than particale board. Back in the late 1980s and early 1990s we mostly used particle board, not MDF, at least not at the shops I worked at. I don't know if it was because MDF wasn't widely available, or if it was more expensive, or if we just didn't know about it. So, my question is: What are your thoughts on using birch plywood for a subwooder enclosure? How do you think the enclosure would handle flex and can you comment about its tonal qualities? What brought this question to my mind is that MDF really is not a great material for holding fasteners (…

I might mess around with this sometime this week. +.6 v would do me good The second link is for float voltage, no need for it, but hooking it up to a switch wouldn't be bad. for a shtf moment while driving. http://www.smartgaug...uk/alt_mod.html http://www.smartgaug.../alt_float.html ---------------------------------------

It's kicking my ass. Who will help me understand it better?

i made a comment on a post on facebook, and tony d'amore said he would be happy to come to SSA and talk about the amp dyno , he actually told me there would be no debate because its science , so here is the topic. where he and we may discuss .. i mean .. talk about science

Ok so I have basic knowledge of rear/front waves and all that mess. My basic question is this: I have a subwoofer enclosure with the port firing to the side and the sub firing upward. Theoretically, which way should I "point" the port to get the loudest result? I can fire it in four different ways You can look at this vid to get a good idea of how much room it has etc. So to get the least amount of canceling or whatever, what do y'all think? I will probably test all four different ways on the TL, but I am just wondering what your theories are... Thanks! PS - pic is as though you were looking down on the car. The red square is the TL mic.

I have done my reading but I still do not know enough, I want to learn how to design them and the strengths and weakness of each. I hope to design and build one of these for an RL-i 8

I see all these vids of people playing 10 or even 5 hz test tones, and i dont really understand how. If you have it tuned to 35, you set the SS at 30 give or take. Then how is it that the sub can play a 10hz tone. Doesn't the box constrict it, and wouldnt it be unable to control the sub below 30 hz or so if tuned to 35? This may sound noob as hell, i dont care lol. Thanks for reading, Mitch

So does anyone wish to share thier secrets? Only thing i've heard is use iron rod instead of wood for bracing.

Alright, so im working on a design for a new box for my NS 18. i am running a saz1500d on stock alternator and soon to be (hopefully) a new xs power battery(probably d5100) im gonna do it right at 5 cubes tuned to 35hz, so it will still be good for daily, and get me a little more spl for when i compete. so since i plan on competing as much as possible i was wondering how much port area to have. ik everybody says 12-16 but i was wondering if i should go more or less or just stick within that range. ik there are some people on here that are really smart when it comes to this subject so thanx in advance. also, is 35hz a good tuning for daily and a little bit of competing or …

Just been wondering why there is no love for them here??? Lol havent had any of their products they seem to be good and at a very good price but the curiosity is killing me at this point and decided to make this question here, wondering is there a dark history of why it seems like they arent very welcomed here in this forum???

From time to time I like to divulge information that helps people understand subwoofer performance. For this particular post I'm going to copy an article from Adire Audio on subwoofer speed. "There's a common misconception out there that heavy woofers must be "slow", and light woofers must be "fast". If a woofer A's moving mass is higher than woofer B's, then woofer A is probably going to be sloppy, or slow and inaccurate. Can't keep up with the bass line. Woofer A simply can't respond as fast as woofer B. There's also this concept that the "acceleration factor" (BL/Mms) is an indicator of woofer speed/transient response. High BL, combined with a low Mms, should give…

I have saved a little money for some wood, and still have glue, clamps and screws from my other box. I wanted to give building a T-line a try since i have heard fairly good things about them. It's just a for fun box, for my 12" visonik i got a while back. Amp and power and all that is covered, it's going in the house for now (no car til who knows when >.<). it's for music, primarily low notes in rap music. i was gonna try for a tuning of ~27-29hz. Now on to the hard part. I havent had alot of computer time recently, but in the time i have had, i couldnt find a calculator for a 1/4th wave transmission line. The specs i can give you for my sub: 250rms rated (takes dou…

hey whats up, I am learning about enclosure design and tuning and was wondering about two terms "imp rise" and "unloading". I breezed through a thread on imp rise and got some very good information. Its the unloading part that im not to clear on. I have a 15" Fi BL Loaded and think that I have damaged it due to unloading (I think). My question is how does it affect the subwoofer, what kind of damage can this do, can a recone kit fix the sub if broken due to unloading. I was having problems where my sub would cut out then cut back in for some reason as I was playing low frequencies. The amp was not clipping or going into protect as I could see all the LED's while this…

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…

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…

I'm looking into buying a 15" BTL fully loaded. My question is, can I tune my box lower than the recommended fs frequency? If I did, would it affect the sub in a bad way? Poor sound quality? Just wondering if there would be a negative effect on the sub. I think the fs frequency on the 15" BTL is 37.9. I like low frequency hip hop and want to tune my box low like 30 hz (at the lowest 25 hz). Is this not a good idea, what would be the result?

I'd like some knowledgeable input on this topic. I have been told to o-scope amps with no load but am wanting to know if any of the following i've been told is true or not. Do not have a load as the amp output from the amp could fry the oscope. Do not have a load as the reading may be off. Well, i've always o-scoped amps with no load. I've o-scoped class d and class ab amps like that with no problems. Today, i attempted to o-scope this class d amp and it got damaged immediately. I contacted the manufacturer and was told it MUST have a load on it or it will do what it did. I ask why and it is due to the amp seeing 0 ohms... Wouldnt the amp go into protect? I dont understa…

What are the advantages of lowering the temperature in the cabin to gain higher dbs. example: refrigerating the cabin to say 50f before taking a spl reading VIA portable refrigeration unit powered by a generator.

hello everyone fist post .i really need your guys help with eq and crossover setting stopped doiing spl and entered the aq seen bud never knew how difficult it will be .got an alpine 9887 dlsr6a s inthe front doors with baffles and jbl coaxil in the back running of an jl xd600/6 2 jl 10w3v3 running of an jl600/1 all active can enyone please recoment good eq and crossover settings any help will be aprecuated thanks

I thought this would be interesting since different materials have been a hot topic recently. As in: Non-pressed paper, pressed paper, pulp, plastic, wood fiber, IMPP, carbon fiber, Aluminum, Titanium, woven fiber, poly, etc... which material would be the best to use in what application etc....

a subs ability to play lower frequencies loud and well? I'm talking about around 30-40 hz. Ive been told that the big factor is in fact not the box's tuning like I thought it was, so what exactly affects the subs performance at those frequencies?

I am not running all of these at once, but I have the option of choosing any combination. I am running 2 vifa Vifa BC25SC06-04 and 2 DDC6.5"s I have a sony xm-4045, 4040 and 6020. I have a cache cloc'd, pac SNI-35, pac sni-15 and fierce FILC20V2 I just picked up an american bass ABX-3.1A crossover which I will be using to replace an older optimus 3 way crossover, and I will be using it for the mids and tweeters. I will level match (to my liking, which will leave the tweeters a little brighter than the mids) on the crossover. My question on that is what the output knob does. It doesn't show any db so I'm guessing that with the knob maxed out, it's simple not…

If you don't want to read my rant: Can someone explain how setting an amp with a DD-1 on track 5 with a 40Hz -10db can still cause me to overdrive my sub with STANDARD music. If I play my sub at 40 out of 47 volume for 1 hour, should the dustcap be warm? Hot? No change at all? 40/47 is less than the rated 1500 watts of the BL (at least at my best guess, especially at 13.8V instead of 14.4V). I want to protect my $1,000 investment in my trunk. I have had a blast with my new Fi BL 15. My head unit's "unclipped" volume is 47 out of 50, and I have never had it past 40. It is very loud, and with a 1500W RMS rating, it is probably getting 1200W at Vol. 40 hooked up to a R…

I went ahead and designed some retrofits for a pair of Bazooka wakeboard tower speakers. The crossover took some time but came out decent in the end...