So I had decided to get a sealed box for my Infinity Perfect 12 for the tight bass, but some guy at an audio shop (off Atlantic) said I can get the same accuracy from a vented if it was tuned right.
offered to make me a custom one for $75 ($50 for sealed). The price is right, and it'll fit my car perfectly.

is he right about the vented thing...it can be as tight as sealed?

8/21/2005 1:01:11 PM

I don't believe it can be as accurate.

8/21/2005 5:06:14 PM

the ported that i've heard seem a little more sloppy than sealed. but those weren't custom built. it doesn't seem like you could get the same tight response with ported if only b/c air is always escaping. see if he can let you listen to one he's built before and judge for yourself.

8/21/2005 6:15:12 PM

... at certain frequencies

you were right to go with sealed

8/21/2005 7:02:12 PM

yea he's right, generally though if u port it and tune to the right frequency u'll lose a little tightness should still be there and u'll gain a few decibles. but i wouldn't pay 50$ for a sealed box and id' only pay $75 if he wraped the box in leather or something go buy ur self a sheet of mdf and some screws and build both see what u like best. shouldn't take too long.
better yet check this out
http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic&f=11&t=069930#000000


[Edited on August 21, 2005 at 7:32 PM. Reason : .]

8/21/2005 7:13:55 PM

After I get back from mowing I'll address this topic. And my answer will be the authority.

8/21/2005 7:48:35 PM

8/21/2005 10:12:02 PM

from other posts he has made on the subject he seems to know his shit

8/21/2005 10:13:16 PM

State409c does know a little about car audio but he aint the fucking wizard and his answer won't be the authority.

8/21/2005 10:36:58 PM

well its been over 3 hrs, so its obvious that cutting grass isn't one of his "authority" areas

8/21/2005 10:50:33 PM

In general a sealed enclosure will be easier to construct to play "accurate" in the average case, but we have several other constraints like the specific driver and it's parameters, how big a box you can tolerate, what kind of music you listen to and then you have the car gain itself. I like to just design a box that is flat and worry about the car gain later (eqs are lovely). Then decide how much space you can give up and from here depending on what type of music you like should determine the box.

I thought I was remembering right that perfect subs like ported boxes better but hopefully you still have the two different inserts for tweaking the Q. I'll summarize the 3 different cases you have (lowQ, midQ, and no insert) and what the optimum ported and sealed box will do.

LowQ

Sealed box of about .72 cu ft with a lower F3 of about 50hz. You will have some car gain below this but overall you aren't going to be able to play the lowest of lows very well with this box. It should be pretty tight though. You could go up to 1cu ft and it would tighten it up ever more at the sacrifice of even more low end capability.

Ported box of about 1.25 cu ft tuned to 29hz will get you to about about 35hz for your F3 point. This is pretty good and will probably be pretty tight all the way up to about 85% of the subs power handling. You can play around with the tuning frequency and box size(bigger) to get it to play a little lower at the sacrifice of a little bit of output.

MidQ
A 2.62 cu ft box will get you down to around 30hz. Not bad, but you pay for it with box size. You could go down to 1.5 cu ft but you start losing the tightness fast and the box will only play down to around 35hz now. You gain a little bit of output from here up to about 80hz.

A 5.5cu ft box gets you down to 18hz. I doubt you have this kind of trunk space. A 1.75cu ft box and a tuning frequency of 23hz will give you about a 1db bump in the output from about 35hz to ~90hz and will play down to 28hz. This box will probably be a little sloppier then the ported box of the lowQ insert

No insert

Optimum sealed box of ~8cu ft. A 2 cu ft box will get you down to 30hz, and give you a bump in the output similar to the ported box just mentioned. In fact, they will sound very similar.

Optimum ported of 12cu ft tuned to 14hz. There really isn't much you can do in the way of a ported box that is going to sound very musical in this case.

If it were me, I'd go with the lowQ insert and the ported box or the midQ insert and the sealed larger box if you can afford the space.

PM me if you have any more questions.



[Edited on August 21, 2005 at 10:57 PM. Reason : i showered, went to the grocery store, and had dinner too]

8/21/2005 10:56:57 PM

bttt

8/22/2005 9:47:18 PM

Do they make preamps that can be mounted in the dash that allow you to specifically adjust the power being sent to the sub?

8/23/2005 8:37:22 AM

haha, what website did you pull that off of...

good info for real though, although a little impractical considering anything ~4'^3 is impractical in a car (your recommendation reflected this...)

ported box tuned to below the resonant freq will be rather linear and extend the low end performance, b/c your tuning below the resonant freq you DEFFINITLY need a low pass filter on the amp in order to not damage the sub, (lots of factors but lets say its control mechanism don't like being operated in this stage).

a professionally built custom fit box for $75 is a pretty good deal... for all the time, effort, materials that it would take me to build you one thats pretty much exactly what it would be worth. (and it'll probably turn out a little better considering he does it ALL the time)

8/23/2005 8:40:43 AM

Quote :

"haha, what website did you pull that off of... "

mybrain.org

I also think it's pretty hilarious when I make a cocky comment, get two haters because of it, then completely and utterly destroy any type of follow up they could make in regards to said comment. Where you guys at?

8/23/2005 9:08:37 AM

no mention of bandpass boxes, I'm disappointed

8/23/2005 10:08:12 AM

i never said i knew more than you about it. but you dont have to be a dick about it.

ps. i dont spend my life on this board.

8/23/2005 10:17:23 AM

Your reaction says a lot about you.

If someone had a Vdub question, and you made the exact reply I did, you best believe I am not going to give you a rolleyes post. Who gives a shit if someone is cocky about what they are good at. It would be different if I were tearing someone down in the process and I'll readily recognize I have done that before, but not in this case, and your rolleye was more or less unwarranted Sometimes it takes being a dick to get your point across and in the realm of car audio where entirely too many people think they "know it", this rule is a good one to go by.

8/23/2005 10:38:56 AM

i cannot personally claim to have heard a ported box com anywhere close to the clarity of a sealed box. i've heard a few bandpasses come very close, but never a ported.

8/23/2005 12:37:28 PM

Were those bandpasses custom made for the application?

8/23/2005 1:15:39 PM

if any one is interested, i have 4 JL Audio 12W3V2D4s (that's 12", W3, version 2, dual 4 ohm voice coil) and an orion extreme 800.4 amp for sale in the classifieds.

8/23/2005 3:30:06 PM

yes, they were custom made. iirc i saw them at the nopi/minitruckin nats @ pigeon forge back in like '02. i'm sure somethings have changed and methods have gotten better, but i was around car stereos alot back in hs and the above statement is from observing everything from amatuers to professionals to factory cars from most of the major automotive audio manufacturers, cars competing for sound quality to spl competitors. as a general rule, if you wanted to win quality you went with sealed, to win spl you went bandpass or ported.

8/23/2005 4:41:25 PM

Fundamentally, a properly designed sealed, ported, and even a bandpass box will sound nearly equal to all but the most discerning ears given the driver is mated correctly.

The problem with your statement is, clarity and SPL don't go hand in hand. I have a hard time understanding how you have heard bandpasses having more clarity than ported boxes, unless you are talking about in an SPL situation, which just doesn't make a lot of sense, it is a non issue.

I meant to mention in my last long post that for my most recent box I wanted to really experiment with a ported design and see how low I could make my 10 play (a w3). I constructed I think a ~2 cu ft box with 2 ports (to reduce port noise) tuned to about 22hz with an F3 near 18hz. In general, I am pretty happy with how low it plays. I have a few tracks that you can feel a guttural mostly inaudible rumble that I don't remember being able to detect with my last sealed box and this same sub. It does feel a little bit less tight than an appropriately sized sealed box but overall I'll take the ability to get lows like a 12" of similar box size as a sealed 12" but with the ability to play a little higher in the frequency range (which eases my power and speaker requirement for my mids).

8/23/2005 5:02:01 PM

big bandpass boxes are the shit, for LFE reinforcement

I have 2 15$ 12"s in a 4th order box tuned for 9.6dB of gain, that rattles the vinyl siding on the house on 400 watts

8/23/2005 5:09:18 PM

bandpasses don't tend to have the same muddyness in the bass as ported boxes unless they improperly tuned.

Quote :

"The problem with your statement is, clarity and SPL don't go hand in hand."

umm... that was what i was saying. if you want it to sound clearest and most accurate then you have a sealed box built, if you want to take to an spl competition you either go with a bandpass or ported.

[Edited on August 23, 2005 at 5:30 PM. Reason : ]

8/23/2005 5:29:46 PM

Quote :

"i cannot personally claim to have heard a ported box com anywhere close to the clarity of a sealed box. i've heard a few bandpasses come very close, but never a ported."

Yea but you stated you have heard a bandpass box come close, then later said bandpass is what you use for SPL, do you see the conflict?

And I am sure you are aware of a bandpass being a sealed box firing into a ported. I realize the comparison to a plain ported isn't 1:1 but if you build a bandpass with an extremely flat and wide passband it will look and sound almost identical to a ported. The reason you probably think they are more clear is the range and rolloff is so limited that dumb users driving ported too hard and dumb box builders making high tuning frequencies generates shitty sounding bass. It is a painful misconception across both car and home audio that a ported box creates muddy bass. Overall though, it is easier to fuck up a bandpass box setup and I am still relatively surprised you have heard good setups.

Quote :

"big bandpass boxes are the shit, for LFE reinforcement I have 2 15$ 12"s in a 4th order box tuned for 9.6dB of gain, that rattles the vinyl siding on the house on 400 watts"

What is the upper and lower F3 range on this? Do you enjoy one note bass?

[Edited on August 23, 2005 at 5:58 PM. Reason : x]

8/23/2005 5:56:07 PM

key word LFE reinforcement

f3l=26Hz f3h=54Hz if I recall correctly, also in that configuration a second sub rolled in above the 9.6dB point so the system wasn't really that peaky

8/25/2005 4:21:55 AM

Quote :

"a professionally built custom fit box for $75 is a pretty good deal"

For that price it ain't going to be a tuned box...just some mdf cut to fit the inside of your trunk a little better.

8/25/2005 5:47:43 AM

I know installers in charlotte that would build custom boxes for that cheap if they liked you and were pretty bored... of course that place is no longer in business

8/25/2005 6:18:14 AM

^^^ Me thinks you are lying out your ass.

8/25/2005 7:31:48 AM

fair enough



[Edited on August 25, 2005 at 8:30 AM. Reason : and before you start crying about continuity the pics are from different times]

8/25/2005 8:22:08 AM

i was meaning a hell of a lot closer than the ported boxes i've seen, like i said tho, this was 3 years and some change ago so my memory may be a little off and they may have been ported and i got my shit backwards, but i do remember that the most accurate subs heard and made mental note of were always in sealed boxes, usually in factory vehicles. i remember memphis audio and rockford fosgate had some great show vehicles back in the day. jl had a sweet expedition with several 12" in the cargo area that sounded pretty damn good as well.

8/25/2005 8:24:03 AM

Quote :

"f3l=26Hz f3h=54Hz if I recall correctly, also in that configuration a second sub rolled in above the 9.6dB point so the system wasn't really that peaky"

What is the second sub? You might not be lying, but you are starting to seem like an idiot.

8/26/2005 8:10:10 AM