chio987

now i know this isn't EXACTLY 3rd gen but it is audio...so please gimme a hand with this...and if it must be closed can someone let me know of a good audio forum...i used to use carstereos.org (S.I.N.) but it seems to have died down alot

I have an Alpine Type R SWR-1522D (i think, i don't think it's the 1542D) anyway, i was looking at the owners manual and this is what it says and it seemed odd to me

optimum sealed box

Ex box dimensions-------------------------16.5 x 16.5 x 15
gross internal volume----------------------1.75*3ft
net internal volume-------------------------1.625*3ft

optimum vented box

Ex box dimensions--------------------------19.5 x 16.5 x 20
gross internal volume-----------------------2.9*3ft
vent area-------------------------------------22.5*2in (15" x1.5")
vent displacement---------------------------0.51*3ft
Net internal volume-------------------------2.25*3ft
F3, ripple, Fb (not sure what this is)-----27Hz, 2.7 dB, 30Hz

i used to have an old RF 15 (from like 96) and it had a 3 cft sealed box....should this sub really be a 1.75???

http://www.alpine-usa.com/images/pro..._SWR-1522D.pdf

so here is the box that the sub is in now...to me it seems like it's too big idunno....sry about the port size, i don't know for sure how deep it goes

thaforce

If you took that woofer to a pro audio shop, they would use those specs to make an enclosure for you. That is the airspace that speaker needs to perform at that volume level in that frequency range.

If you are looking to hit a specific frequency note with the woofer you can play with the airspace, but for broadrange overall performance, its best to stick with mfgr specs.

chio987

i'm 90% sure that i got the port size...i bought the sub and amp from a pro audio shop and had them put it in (i didn't feel like dealing with it...too busy) and he said that the box was a little small but the one he wanted to use wouldn't fit....idunno...seems kind of fishy

Gummie

If you hadn't said it wasn't going in a thirdgen how would we know any better?

ICIXSound.COM Community. Not a big carstereos.org fan myself. Just a lot of opinionated fanboys throwing their ideas around with no real information to back them up IMO. Sure, there are some good users but a lot of threads get trashed by people who have no idea what they’re talking about.

The #### Alpine naming system is pretty easy. The first two numbers are the speaker size (15 in your case). The third number is coil impedance. The fourth number represents the number of coils. If you want to find out which you have take a multimeter to one of the coils and check its resistance.

As for the box, here's what they recommend vs ideal.



Their number isn't that far off from ideal. What really matters is Qtc of the system; that is how the woofer moves. The lower the Q the sloppier the driver will be, the higher the tighter. A Qtc of .71 is considered ideal and honestly their box probably won't sound that bad compared to an ideal box. Odds are marketing chose that number. There's been a push for smaller boxes that joe shmoe can fit in their car without loosing much space. Would you like to have to build a 2.4 ft^3 box or a 1.75 ft^3 box if you had limited trunk space?

Their vented box is more of the same:



The yellow is the more traditional box alignment where one tries to achieve a flat response and the red is Alpine's box, which will give you a nice little boost in output while not allowing you to play as low. They’re also trying to avoid recommending a 5.5 cube behemoth of a box once you get port displacement factored in. In this case I would side more strongly against the alpine box.

You have to know the port length This will literally make or break your box as it determines what frequency your box is tuned to. Saying something like this is like saying my cam has .5" or lift but you have no idea what the duration or timing is. Ask whoever made the box or check with whoever you bought it from and get back to us.

edit - took too long typing. Making another reply

chio987

i'll just have to take the sub out of the box and then know for sure and then i'll also know for sure if it's the 1542 or 22.... i was supposed to get the 12in but they were on back order for a few weeks so they cut me a deal to go with the 15 so i didn't really know too much about it...anyway, so if i'm understanding this, their sealed is close to what it should be but the vented is small and the box i have is closer?


P.S. altho it's been a while, u're box build was awsome and helped alot with the fiberglass box for my GF's S10 and my eventual glass box for my bird

Gummie

Completely untrue. Manufacturer spec boxes are generally too small for a woofer. This is to try to sell more woofers if the deciding factor for someone is space. If someone needs trunk space (or has a truck) and doesn't really know what's going on they will most likely buy from whatever company recommends the smallest box. No reputable shop will use them when designing a box. They will use winISD (what I'm using for my pictures), bass box pro, or the likes to derive the proper box from the t/s parameters of the woofer.

It doesn't seem fishy to me at all. Boxes tend to get big when you're dealing with drivers this size.

Working backwards I derived the following info about your box:

Total volume = 3.803 cubes (assuming 1" thick MDF based on your port)
port displacement = .859 cubes
adjusted volume = 2.944 cubes (3.273 cubes w/ .75" MDF)
port size = 2.5 x 16.5, which puts port area at 41.25 in^2
port length = 36 inces

I plotted both the 1" thick MDF and the .75" MDF versions for your viewing pleasure.



To the eye this looks fairly similar to the Alpine spec box in terms of response. There's actually an alignment along these lines that's fairly common called BB4. The box I'm considering ideal is a QB3. To each his own I guess but I wouldn’t have built that kind of box unless you’re into boomy style of music (rap, dance, etc).

You don't have to take the sub out of the box, just measure the resistance at the box. If it's 1 ohm then you have 2 ohm coils wired in parallel. If it's 2 ohms then you have 4 ohm coils wired in parallel. Either way isn’t going to impact the way the woofer behaves much, if at all.

To clarify about Alpine’s boxes vs boxes I would recommend:

Sealed – Alpine’s box is too small

Ported – Alpine’s box is aligned BB4 style. This produces a peek in output, which makes your system louder in the peak’s frequency range. This is a good thing if you like music that doesn’t have a technical bass line (again rap, dance, etc) or if you’re trying to compete in terms of output, but it’s not a good thing if you’re a metal head.

Your ported box – While your box is physically larger than Alpine’s it shares the same general response so what I said above applies here. If you made your port longer (and thus tuned the box lower) it would flatten out your response a pretty good amount.

Do you not like the way your box sounds or are you just trying to double check what the shop did for you? If you’re happy then why change it? If you’re not then post again and I will try to help you fix it.

Incidentally, from what I’ve heard Type-R’s sound horrible ported.

Thanks for the kind words I really need to get back and bondo/carpet the box so the thread will probably be coming back up to the top sometime in the relatively near future. Money has been going elsewhere since then so I haven’t had a chance to finish it up.

Stealthy-One

I agree with what Gummi said, ported my Type R sounds like azz. I wasnt happy with it at all. then I made a sealed box and it sounds SO much better. granted its a 10" and running on about 350W RMS but it still is plenty for my car.

Jim85IROC

iTrader: (2)

There's no reason that a particular sub will sound so bad in one alignment and so good in another unless the sub's parameters are such that you simply can't get a flat frequency response with one type or the other, which isn't the case with this sub.

I think it's reputation for sounding bad in a ported box is due to Alpine's box suggestion. The bump centered at 45hz is going to give this a bit of a one-note type of sound, although the bump is only about 2-3dB, which is less than I'd expect in a box that small. If you build the 5 cube box and tune it to 20hz, I think you'll find that the sub sounds a lot more realistic than it does with Alpine's suggested box. If you need a box that small, I'd drop the tuning frequency to about 22hz. That smooths out the bump, and still gives you an F3 of 30hz, which is lower than anything you'll hear from popular music anyway. The drawback to this alignment is that the port is going to be insanely long, but you should be able to fit it into a 2 cube box if you use an elbow.

Another reason why ported alignments don't always sound the best is that in a car, you have a lot of cabin gain that will nicely augment a sub with a smooth low frequency rolloff like you generally get from sealed boxes. Use something like this alpine that's flat to 20hz in a ported box, and once you put it into the car, it gets VERY bottom heavy, which can make it sound bloated, thick, slow, or some other commonly used adjective. For this reason, most people prefer sealed alignments in cars, especially with bigger subs. It has nothing to do with the sub's ability, but just the massive amount of gain you get at low frequencies in a tiny space like your car.

chio987

well the reason i opened up the manual was bcuz i did want to try and go with a smaller box, that's when i noticed how small their boxes were. when i bought the sub, like i sed it was suppose to be a 12, so i maybe thought that the guy just rushed some random box in just to try and get the job done. the last main thing is that when i start to turn it up the sub starts to pop and sounds bad, but it sounds great at low vol. idunno it's the amp and HU rn't setup right or if the amp i have is too small (is was supposed to be for the 12in) but they sed it would be enough for the 15....another thing is that i hear ALOT of people say how caps r a waste of money but i was talking to someone one time who went thru school for electronics and builds circuit boards and **** sed the i should be using atleast a 1 farad (the way he explained it made sense and my lights dim when i turn it up) maybe later tonight i'll post a vid of what i'm talking about...i'll just need to find a good song it happens on

EDIT: i just went out and checked the ohms at the terminals and it was showing 3.8....i even added a pic of what it shows just to be sure...it did jump up to 4.4 but it stays at 3.8

Stealthy-One

ok, you have one sub and are thinking about getting a Cap so that your lights dont dim, is that right? well let me try to explain something here.... when your sub hits and demands a lot out of the amp there is a huge draw on your cars electronic system hence the lights dim. You with me there? ok, so now you add a cap. now when the bass hits the amp sucks mass ammounts from the cap, which in tern STILL sucks a huge ammount from your cars electronic system. I understand using caps with multiple amps, batterys and HUGE ammonts of poewer, but not on a single sub.

Do a quick search for the "Big Three" Basically they are just small upgrades you do to your cars wiring under the hood to help out the electronics... Alternator to batt positive, Batt neg to block, Batt neg to chassi. upgread these wires with 4G or better and it sshould help out a bunch.

i have a 400W amp and a 100W amp. I had the disco lights effect with heavy bass aswell. After I did the Big Three It went away.

If you still want a cap, I have a stinger 1Farad cap in my shed Ill sell you. 20 bucks +shipping.

Gummie

I was thinking about tacking cabin gain into my post but it was already getting too long without it. Thanks for adding that in though.

You have 2 ohm coils wired in series to 4 ohms. That's slightly odd a dual 4 ohm sub would most likely have been a better choice for you if your amp can’t handle a 1 ohm load. What amp are you running out of curiosity? Also, that popping noise could be a number of things. It could be that the sub is bottoming out if you don't have a subsonic filter. It could also be the amplifier clipping from an improperly set gain.

The number of subs doesn't matter at all. The only thing that matters is the amount of amplification. Caps will fix dimming by smoothing out the spikes in current pull, there's no argument about that. They are, however, a band-aid solution for a weak electrical system, I don't care what anyone has to say about this. Even if you're running a huge system there's no need for a single cap if your have a strong enough electrical system.

I agree 100%

https://www.thirdgen.org/forums/car-...t-keep-up.html

Upgrade your grounds. Search the big three. It will cost you about $10 and will be well worth your time.

Stealthy-One

Gummie, I was kinda referring to the competition vehicles with 10 subs 20 amps and caps to smooth it all out.

Jim85IROC

iTrader: (2)

A capacitor can still be beneficial in a lot of systems (regardless of the number of amplifiers), but it is still absolutely necessary to do the big 3 first.

Gummie

I know, just giving you a hard time

chio987

here's the amp i'm using
Alpine Electronics of America, Inc.

EDIT: i'm going back thru to make sure i'm understanding everything...i know some basic info about car audio but not near what u guys know...i'm not sure about the ohms setup and stuff like that

Gummie

That sub is a horrible choice for your amp and vice versa (this is directed at the shop and not at you - take no offense). I wouldn't say that your amp is completely up to the challenge of pushing your 15" Type-R. It would be one thing if the shop was somewhat intelligent and sold you a dual 4 ohm sub, that way you could wire the amp down to 2 ohms and get 600 watts out of it but as it stands you're only getting 400 watts. Not that the 200 watts is going to make that much of a difference but still.

There are two reasons I asked about the amp. The first was to see what its output was to see if there was the possibility that you were pushing it too far and thus clipping the signal, which might explain the popping sound you're hearing. Who set the gain and are you sure it’s set right? The second reason I asked was to find out if you have a subsonic filter or not (some people bridge two channel amps for their substage and thus don't have a SSF). If I had to bet I would say that your SSF is currently defeated. Set it to 30 Hz. Once your sub tries to produce frequencies below the tuning frequency of the box its suspension can unload because the box is no longer controlling the cone’s excursion. This can cause over excursion, which is obviously bad.

The “ohms stuff” is pretty easy. The numbers reflect the speaker’s impedance/resistance. This determines what load you can wire to your amp. Ideally you want to match your speakers to your amp both in output (can the amp produce the amount of power needed) and in terms of load (is your amp 1 ohm stable, 2 ohm stable, etc). In this case since your amp isn’t 1 ohms stable the dual 2 ohm sub was a bad choice because the only ways you can wire it are for a 1 ohm load or a 4 ohm load. A dual 4 ohm sub would be much more idea because you could wire it down to 2 ohms, which your amp can handle, and that would give you access to more power.

Post up if you have any questions. Someone will answer them I’m sure.

chio987

sounds to me like i was right about this shop...they were just trying to get whatever they could just to keep the sale...i was even willing to go with the M-1005 amp with the 15 if it would be better...altho i have to look on the good side (if u can call it good) is i paid for the 12in, they ate the rest

ya...where do i go from here? switch the sub...maybe the SWR-1242 with my amp? go with a different amp? or sell both the amp and sub and go with something completely different....can't say i'm not pissed off about this, i'm not going back to that dam shop.

chio987

i think i get it...my amp is running at 400 watts at 4 ohm at 14.4v
1.i doubt my car runs at 14.4, more around 13.8 (am i right on that...does it matter?)
2.my sub should have 350 MORE watts running to it.

not sure if i'm understanding this CORRECTLY but either way my sub is underpowered and shouldn't be using this amp...i think

Gummie

[QUOTE=chio987;3077504]sounds to me like i was right about this shop...they were just trying to get whatever they could just to keep the sale...i was even willing to go with the M-1005 amp with the 15 if it would be better...altho i have to look on the good side (if u can call it good) is i paid for the 12in, they ate the rest[quote]

True, but you still probably would have been overpaying on the 12" anyway. They’re not quite as bad as you’re making them out to be – they didn’t try to sell you on a bigger amp.

Keep the sub. It's a decent sub and there's no real reason to replace it.

Before you do anything, do what I outlined in the previous post: check to make sure that your gain is set correctly and set the SSF so that your sub isn't going to bottom out.

After that try to fix your box by tuning it lower (all you need to do is make the port longer). Tuning your box lower will flatten out that bump in your response nicely. If you’re still not happy try another box before you buy another amp. This is by far the cheapest route.

14.4 vs 13.8 isn't going to make a huge difference but it will make a small impact. Regardless, your sub is underpowered. This won't make it sound bad, it just means that it won't be able to play to its full potential, which might not be a bad thing depending on your tastes (but it sounds like you want more). The only reason why I asked in the first place was to see if someone might have turned the gain up to compensate for the amp’s output, which is causing the amp to clip because it’s getting pushed too far.

Again, before you do anything check the gain and set the SSF. You shouldn’t have any weird noises coming from any of your speakers under any circumstances.

chio987

i checked out the settings on the amp and here they r

subsonic filter............15Hz
LP slope....................12dB
LP filter.....................110Hz
gain..........................0.1v
bass eq.....................+10

Gummie

Your subsonic filter is set wrong. It should be set to the tuning frequency of the box, which is around 30 Hz.

LP slope/filter are fine.

Your gain hasn't been touched. You might want to try adjusting this; it will give more output at a given volume. Here's a link that will explain how to set your gain correctly: http://icixsound.com/vb/showthread.php?t=27819

Turn down bass boost or just turn it off all together. It's just a fairly narrow boost in output that's generally around 65 Hz. Not what I would call ideal if you want a nice sounding system. Sure, you will loose some output but you should make up for it with your gain set correctly, not to mention everything should sound a good deal better.

chio987

after a quick read it looks like my setup and my goal is the same as thiers...400watts at 4 ohm= 40 volts...i see that all the bass and eq's should be set at 0 but on my HU (alpine CDA-9847 i believe) it has a subwoofer setting 0-15...should that be all the way up or down?

Gummie

Down is the norm but I'm going to say up in the case of Alpines and the like that actually change the voltage of the subwoofer preout instead of just boosting the bass.

chio987

well i adjusted the gains today and the higher the gain # the less bass there was....anyway, i ended up with a 0.3v gain at 40 volts...thanks for all the help

Gummie

Not a problem. The dial is a little misleading - the numbers around the gain **** are labeled for preout voltage. That is a deck with 7 volt preouts would theoretically line up with the 7 volt mark, 5v deck with the 5v mark, etc.