Fi Q 12 Ported or Fi Q 15 Sealed ?

 

Bronze Member
Username: Shopvac

Post Number: 51
Registered: Jun-10
ok guys, I have no clue when it comes to difference is sounds with respect to ported vs sealed enclosure, I have done alot of reading but never physically heard the difference in sound for these enclosure type. My question is which one would prefer and why? Suggestions would very much be appreciated.

1. Fi Q 12 Ported @ 32 Hz, 2.35 cu ft.
2. Fi Q 15 Sealed 2.5 cu ft.
I have space for up to 2.5 cu ft, Amp SAX 1200D, budget ( I can buy any one of the 2 subs), daily driving, both subs are 1000 watts rms.

Thanks,
Shopvac.
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 1
Registered: Oct-10
Sorry if this isn't new info, I don't know how much you know.

A ported box rolls off at -24dB per octave (30-40hz is an octave), while a sealed box with a Q of .707 (flat response) rolls off at -12dB per octave. Ported boxes are generally +3dB over sealed. To have the generally same output as a ported box, a sealed box needs twice the cone area (+3dB) than the ported box. If you can afford the space and power to make up for lost output than a sealed box is ideal for various music genres.

The sound a ported box tuned between 30-35hz is hard to describe. It sounds "poofier", "fatter", "wider", and it's peakier in frequency reproduction.

A sealed box sounds, depending on the driver T/S, "flat", "crisp", "quick", and maybe "airey". A lot of sealed drivers have more output below 30hz than a ported box, but not if the ported box is tuned to 30hz (than it's +3dB). The sealed box would be +12dB @ 20hz over the ported box though. This is why I liked sealed boxes for rap like DJ billy E and crazy lowlowlow bass.

Some subs you can't use in a sealed box, and some are much better than others.

With a sealed box, there are 4 things you need to determine the Q (as in QTC, as in frequency response) and the frequency roll-off. You need the driver T/S, specifically the F/S, QTS, VAS (in cubic feet, usually states in liters), and the NET box volume.

Q .4 = more bottom end, less top
Q .707 = flat response
Q .1 = less bottom end, more top

In a sealed box, the difference between different impendances (DVC 2ohm, SVC 4ohm, etc) can be huge, even though it's the same model. Some brands don't show both their D1 and D4 specs so it's hard to know what you're really going to get performance wise.

I would use the sealed 15 for mostly rock tunes. I would use the ported 12 for rap, but only if it was tuned to 30hz.

Use this:
http://www.carstereo.com/help/Articles.cfm?id=30

Fi Q 15 sealed:

DVC 1ohm
QTC = .5896
FC (roll-off) = 46.59 HZ

D2 2ohm

QTC = .604
FC = 46.16 HZ

The DVC 2ohm is by a small margin better because it's a little flatter and rolls off at a lower frequency.

Q 12 (DVC 2ohm/wires into 1 ohm) efficiency 86.3dB
Q 15 (DVC 2ohm) efficiency 89.4dB

= 3.1dB

Therefore, the Q 12 ported and the Q 15 sealed are likely to be very similiar in output, depending on the frequency the ported box is tuned to. The sealed box is -12dB @ 36.16 HZ and -24dB @ 26.16HZ.

I'd say that the ported box, if not tuned higher than 36.16 HZ, will have similiar output until 26.16 HZ, where the 15 would take over. Like I said it's ideal for lowlowlow bass.

I wouldn't choose that driver for a sealed box, I would choose any driver with an LMS motor - Soundsplinter RL-S 15, TC sounds, Eclipse SW8210 (12") / SW8010 (10"). If you can fit 0.5 cubes more space, and get an amp that does 1500W @ 2ohms (Kicker), it would be much better, and probably wouldn't be over your budget.

The Eclipse SW8210 in a sealed box models to QTC .5 / FC @ 28hz in 1.5 cubic feet, efficiency 86.5dB (+3dB for two drivers, compared to the single Q 15, is roughly the same output at 89.5dB). You also have +50 square inches of cone area. It rolls off a hell of a lot lower, so you gain a lot of output between 28-43 HZ over the Q 15. They're 750W RMS, and Eclipse recommends up to 1500W if it's totally clean power (batteries, alts, big 3, etc). They're also only $150 each from Sonicelectronix. They only come in SVC 4ohm so two would be wired into 2 ohms (kicker has an amp that does 1500 @ 2). If your amp does 500W @ 2ohms than the Q would have around the same output... just less low end. They SW's sound really tight & clean in 1.5 cubes, they're lowlow end specialists.

If you could fit 3 cubes sealed for 2 Eclipse 12's, that would be better than both the Q setups. You can't put 3000W on a Q either. Maybe later you'll want more bass but can't fit it, then you'll want to double the power (+3dB). I dunno, just throwing suggestions. I figure you're either wanting mostly SQ or you're going to forever be wanting more bass like most people.

If you're sticking with the Q series, I'd do the sealed 15 (with options) and then see how much more power over RMS it can take in 2.5 sealed.
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 2
Registered: Oct-10
I would have suggested the Soundsplinter RL-S 15" 2000W RMS/LMS motor (I'm not so sure) for 3-5 cubes sealed, but it's like a million dollars and it doesn't model that great. Reviews say its the best SQ sub hands down, it has zero distortion.

Scratch what I said about upgrading to 3000 @ 2ohms. If you want to upgrade, use a Fi BTL 12 in 2.35-2.5 cubes @ 30-35hz on 3000-3500W (the new ones are on the site now! WOO!).

https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154cc4b753488e0/s hopdata/0050_Speakers/0010_BTL/product_overview.shopscript
 

Platinum Member
Username: Rovin

1 15 = 153 DBs ...Trinidad & T...

Post Number: 16757
Registered: Jul-05
wow u sure had the sparetime to type all that ...
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 3
Registered: Oct-10
It took maybe an hour LOL!
 

Platinum Member
Username: Glasswolf

Post Number: 13998
Registered: Dec-03
All math aside, let's look at this a bit more simply.
What is the rest of your system?
Front stage and amplification for that?
Any EQing between the source and amplifiers?
What car are you using?
What sort of music do you enjoy?
What's your typical volume level?

These questions will help us offer a suggestion for the enclosure and choice of sub. Typically unless you're a hardcore SQ guy and dislike excessively high output at the low end (lots of bass) then the ported enclosure is the better suited choice in a car for most people.
 

Gold Member
Username: Skdooley

Roanoke, VA Usa

Post Number: 1266
Registered: Oct-09
Wow. That was one of the best explanations I've ever seen. Mad props to you sir.
 

Bronze Member
Username: Shopvac

Post Number: 52
Registered: Jun-10
First, I must thank Lord Huggington for that detail explanation "excellent" am sure many others have learnt from those posts ! (the best explanation I ever seen as well ) I would certainly take everything into consideration...

@ GlassWolf -->
Front stage and amplification for that? (looking at the DLS Reference MS6A, or another DSL 2 way component set, and SAX-100.4, may add mid bass driver later)

Any EQing between the source and amplifiers? (not at the moment, if you have a suggestion please say..)
What car are you using? (VW passat 2000)

What sort of music do you enjoy? (generally listen to all type, but mostly reggae)

What's your typical volume level? (hmm reasonably loud I would say)
 

Gold Member
Username: Gcs8

Atlanta, Ga

Post Number: 1533
Registered: Sep-09
best thread ever.
 

Platinum Member
Username: Glasswolf

Post Number: 14003
Registered: Dec-03
LH is correct in that the Q series isn't designed for 3Kw of power, and even a fully loaded model is only designed to handle about 1500 watts at the most. Less would be safer. While I agree that the LMS and XBL^2 motors are outstanding designs (without getting into the pros and cons of over/underhung magnet structures and so on) the Q is also very linear at high excursion, and does quite well with the high Qts option (specs not given on their site) in a sealed box. I run a single Fi Q18 sealed in my own setup, and have used the Q15 sealed with high Qts as well with a very flat response with minimal equalization.

With the power you're talking, the SS RL-P would be a better choice, ported since you would probably benefit from the accentuated low end extension. I'd tune the enclosure lower, around 28Hz with a 12" if the Fs/F3 supports that (I don't have the RLP specs in front of me right now) and you'll get great output. You could really go with a smaller sub. People have a warped idea often times of just how much power is really needed to get a lot of output. A fairly sensitive sub, in an enclosure with decent gain will have plenty of output with less power than you'd think.
I've been in the 140s with a pair of 12" subs built in 1989 in a ported enclosure powered with a single class AB Orion 280GX amp running @ 2 ohms stereo (160 watts RMS x 2). 3,000 watts is really more than you should need for any daily driver application, and the less power you have in the car, the less likely you'll be to need even more expensive upgrades to the electrical system to avoid damage to the drivers.
 

Platinum Member
Username: Glasswolf

Post Number: 14004
Registered: Dec-03
OK I got unlazy and wrote out a more thorough response to LH's post, mostly by just editing his response and adding in my own notes.

A ported box rolls off at -24dB per octave, while a sealed box with a Q of .707 (flat response) rolls off at -12dB per octave. Ported boxes are generally +3dB over sealed. To have generally the same output as a ported box, a sealed box needs twice the cone area, or double the power (either option would add +3dB). Keep in mind also that a ported enclosure requires more volume than a sealed enclosure, both in raw air volume, and for the displacement of the port (tube or slot) itself.

A ported enclosure tuned low (25-35Hz range) will sound accentuated in the deep, "feel it in your chest" frequencies, and give a richer, fuller feel to the music, whereas tuning in a higher range for more gain from the enclosure (45-65Hz range) will sound very "boomy" and a bit "hollow." A lot of rap music focuses on this range, and works well with a ported box tuned to around 45Hz, but for most musical tastes, a lower frequency is generally preferred.

The sealed enclosure is characterized by excellent transient response, good low frequency power handling, smaller box size and lower sensitivity to misaligned parameters when compared to other alignments. However, sealed enclosure systems tend to suffer from higher cutoff points and lower sensitivity than the other enclosure designs. A sealed enclosure will tend to sound more detailed and "quicker" (tracks better) due to having a lower transient delay than a ported box, but as a trade-off, you will lose the gain in output at or near the tuned frequency of a ported box. A sealed enclosure will, anechoically (meaning the response on a computer graph, and not affected by environment (the car's interior)) roll off naturally at 12dB noticeably higher than that of a ported box. However, the thing to keep in mind is a factor called "cabin gain," which modifies the response of any enclosure in a car cabin by adding gain to the enclosure's response below the transfer function, which is more or less the car's sympathetic frequency, of close to it.

The Thiele-Small specifications of a speaker will determine if the speaker is better suited to a sealed or ported enclosure, or if it's in that gray area in between that allows the speaker to work in either environment equally well.
The following are two quick ways to determine, as a starting point or rule of thumb, what enclosure is best suited to a speaker you may be considering:

Efficiency Bandwidth Product (EBP)
EBP = Fs / Qes
50 or less = best used in a sealed enclosure.
50 - 90 = flexible enclosure options.
90 or greater = best used in ported enclosure.

-OR-

Qts < 0.30 - ported
Qts = 0.30 - 0.50, use ported or sealed.
Qts > 0.50 sealed

EBP is typically the more accurate means of determining the ideal enclosure, as strictly using the Qts can be tricky, as some variables can actually affect this outcome, and mistakenly indicate the wrong type of enclosure for the speaker in question.

LH has also stated that;
With a sealed box, there are 4 things you need to determine the Q (as in QTC, as in frequency response) and the frequency roll-off. You need the driver T/S, specifically the F/S, QTS, VAS (in cubic feet, usually states in liters), and the NET box volume.

Q .4 = more bottom end, less top
Q .707 = flat response
Q .1 = less bottom end, more top

In a sealed box, the difference between impedance (DVC 2ohm, SVC 4ohm, etc) can be huge, even though it's the same model. Some brands don't show both their D1 and D4 specs so it's hard to know what you're really going to get performance wise.


Because the impedance of each coil, as well as the number of coils affects the electrical resistance to current, as well as the length of wire wound around the former in each speaker, several of the T/S parameters are affected by the coil configuration you choose. This also applies to using a DVC sub and choosing to use the coils in series, parallel, or only choosing to use a single voice coil to achieve the desired load for the amplifier being used.

I would use the sealed 15 for mostly rock tunes. I would use the ported 12 for rap, but only if it was tuned to 30hz.

LH notes below:

Use this:
http://www.carstereo.com/help/Articles.cfm?id=30

Fi Q 15 sealed:

DVC 1ohm
QTC = .5896
FC (roll-off) = 46.59 HZ

D2 2ohm

QTC = .604
FC = 46.16 HZ

The DVC 2 ohm is by a small margin better because it's a little flatter and rolls off at a lower frequency.

Q 12 (DVC 2ohm/wires into 1 ohm) efficiency 86.3dB
Q 15 (DVC 2ohm) efficiency 89.4dB

= 3.1dB

Therefore, the Q 12 ported and the Q 15 sealed are likely to be very similiar in output, depending on the frequency the ported box is tuned to. The sealed box is -12dB @ 36.16 HZ and -24dB @ 26.16HZ.

I'd say that the ported box, if not tuned higher than 36.16 HZ, will have similiar output until 26.16 HZ, where the 15 would take over. Like I said it's ideal for lowlowlow bass.

I wouldn't choose that driver for a sealed box, I would choose any driver with an LMS motor - <snipped>
If you could fit 3 cubes sealed for 2 Eclipse 12's, that would be better than both the Q setups. <snip>
If you're sticking with the Q series, I'd do the sealed 15 (with options) and then see how much more power over RMS it can take in 2.5 sealed.


The thing to keep in mind is that for a sealed box, the Q is offered with the High Qts option, which modifies the sub to work better in a sealed box. Unfortunately Fi doesn't list the actual Qts of the "High Qts" option on their website (that I've found.) This makes calculating these things a moot point until that number can be determined with any additional options figured in as well, since options like the additional spider and so on will also alter the T/S specs of the driver.
The Eclipse Ti drivers and similar models are great for small volume sealed enclosures (or at least they were the last time I was selling them some years ago.) Something to keep in mind however, that wasn't mentioned is that the choice of enclosure type and volume of said enclosure will directly affect the power handling of the driver. For example, a ported enclosure has better mechanical power handling than a sealed box. Another factor is the cooling options chosen for the Q if you go that route. The Q I'm using in my car at present is sealed, High Qts, "Cooling," "I-Heat Ring," "Extra Spider," and Dual 2 ohm coils. (run with a bridged amplifier that's 4 ohm stable bridged.) It works very well in my situation, and is getting "1200WRMS." Keep in mind also though, that a "1200 watt RMS" amplifier is rated at 1200 watts RMS on a test bench, with a resistive dummy load, and a full spectrum white noise sinput signal from a tone generator.
The reality is this: Speakers are a highly reactive load. This is especially true for a subwoofer. The enclosure you choose will also affect the impedance of the final load at any given frequency (see: Impedance Rise.) Also you're using a dynamic input source. Music isn't a test tone, and quiet passages will require far less power than louder passages and so forth, again reducing the actual amount of power consumed. Lastly, note that your volume knob won't be at 100% full volume all the time, like it was for the input signal on the test bench when the output of the amp was measured. Every time you audibly double the volume of a sound system, you're using between 6 and 10 TIMES the power from teh amplifier(s) to reach that increase. The same holds true in reverse. A 1200 watt amp will put out closer to 120 watts at half the full output (volume.) Halve that again? 12 watts. You can see how quickly your power requirements diminish as the volume gets turned down. The reality is, even at moderately loud volumes in a car, you're still probably only consuming about 50-100 watts continuously, on average. This is why you can generally use an amplifier rated for 50-60% more output than the driver(s) to which it is connected, at the given load without fear of damage to the speaker(s).

I hope some of this has helped.}
 

Gold Member
Username: Livin_loud

MW2 Addict

Post Number: 3244
Registered: Jan-06
Well, I'm pretty sure there's more good information in this thread than the whole current subwoofer section combined... and possibly every other section.

Kudos.
 

Platinum Member
Username: Glasswolf

Post Number: 14006
Registered: Dec-03
There is quite a bit of good information on this board. It's just a matter of weeding it all out from the garbage.
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 4
Registered: Oct-10
Not bad for a first post x_x

3dB isn't much, it's barely audible with nearly stock electrical - I went from a 2005 RE XXX 12 D2 in 2.2 cubes @ 36hz on 1500W @ 1ohm to two Eclipse SW8200's in 2.5 cubes sealed sharing 750W, and it technically should have been a 3dB loss but I couldn't tell a difference. Unless you have like 3-5kw, you're not going to tell the difference between 1000W-2000W. I'd say you'd need to tripple the power for it to be a nice audible gain.

You don't need much power to get loud. You can gain dB's by the install alone. Ported correctly + sealed from the trunk and whatnot + 1/0 gauge wire + big 3 + deadening, is a win with any sub & amp.

Cone area FTW.
 

Platinum Member
Username: Glasswolf

Post Number: 14008
Registered: Dec-03
Actually, you changed sub make and model, which means the entire specs of the drivers changed in addition to the change in power and number of drivers, so there's no way to know how much you gained or lost at any given volume. Especially with the change in amps and gain settings as well. The only time you can strictly say "I gained or lost 3dB" by math alone is by changing one, and only one thing in an otherwise controlled setting. Say, adding a second sub to the amplifier, or going sealed to ported for example. Your calculations wouldn't really hold up, so to speak. Sorry. +3dB is noticeable. Very noticeable. It's just not nearly double the audible volume. If you want to see what I mean, find a good home stereo system with a preamp or AV receiver that measures volume in "absolute" figures using decibels (example: Onkyo/Integra Research) and incrase the volume from, say, -60 to -63. You'll see exactly what a 3dB change should sound like.
 

Bronze Member
Username: Shopvac

Post Number: 54
Registered: Jun-10
Wow, koodos indeed !!!!

Well, I must say as a newB I dont understand everything, but I am extremely happy with the splended responses, I been waiting a while to see a thread like this, and must say thanks LH and GW for their precious time to explain.

Please guys continue if you can , all eyes on this thread !!! lol...
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 5
Registered: Oct-10
Stock electrical (00 Sunfire GT 90A alt) must make a 1500W amp put out around 1000W, so the difference I was hearing was more like 250W. There was a tiny difference, but not one to mull over. Better highs vs better lows.

I don't know what 3dB really sounds like, but I've played with HT setups that use "-" before the number, does that signify absolute numbers?

I've done a lot of calculations for popular sealed drivers in their minimum & maximum air spaces. Some noteably good ones are the RE XXX, RE MX, Eclipse SW series, and AP Axis.

Fi SSD
.7 cuft = Q .6068 @ 50.74 Hz
1.2 cuft = Q .5185 @ 43.35 Hz

Fi Q 12
1.5cf3
QTC = .4776
FC = 44.15 hz
F3 = 73.18 hz

Audiopulse Axis 12 2500W
.6cf3 = 47.37 hz
1.4cf3 = 36.31 hz

RE XXX 12 2000W
1.267cf3 = Q .707 / 36.75 hz

Soundsplinter RL-S 12 - SPL 80.5db - 2000W
2cf3 = 37.78 hz
2.5cf3 = 36.52 hz - optimal
3cf3 = 35.66 hz

SSA XCON 12 1750W
.9cf3 = 49.91 hz
1.5cf3 = 43.76 hz

SSA Icon 12 1000W
1cf3 = 47.68 hz
1.35cf3 = 43.77 hz

Soundsplinter RL-P 12D4 1000W
1.35cf3 = 41 hz

JL W7 1000W
1cf3 = 49.64 hz
1.5cf3 = 43.46 hz
2cf3 = 40 hz

Image Dynamics IDMAX 12D4 1000W
1.5 cf3 = 44.15 hz
Graph http://www.*********************/man...DMax12D4V3.pdf

Image Dynamics IDQ 12 500W
1.3725cf3 = 46.75 hz (Q .707)
Graph http://www.*********************/man...20D4%20V.3.pdf

SSA Dcon 12 300W
.9cf3 = 58.67 hz
1.2cf3 = 52.71 hz

SW8210
1 cubic foot
QTC 0.6799 (0.0271 from 0.707)
FC @ 30.04
F3 @ 31.29

1.5 cubic feet
QTC .6081
FC 26.87

2 cubic feet
QTC .5688
FC 25.13

RE MX 18
Recommended 4 cubes: QTC .8695 / FC @ 35.08 HZ
7.25 cubes: QTC .7031 / FC @ 28.37 HZ
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 6
Registered: Oct-10
How about a gigantic sealed enclosure for one 18"... like a limited IB but with a nice response?

RE XXX 18 V4
Recommended 4 cubes
Q 1.2609
FC 35.76 HZ
F3 25.96 HZ

26.1 cubes - perfect
Q .707 - perfect
FC 20.05 - perfect
F3 20.06

Imagine the lows on that thing, -12dB @ 10hz. You could wall that off in a car and just let it use the space behind it, my alero trunk is about 12 cubes (not squared) and about 12 cubes half way to the front seats. I want one for HT!

The 15 also models great.

RE XXX 15 V4
7.37 cubes
Q .7071
FC 26.96
F3 26.96
 

Platinum Member
Username: Glasswolf

Post Number: 14009
Registered: Dec-03
OK, first, I've written some papers on this topic before, but in short, a 90A alternator will be able to generally supply about 40A of current to teh audio system (if we're talking HOT ratings here and not Cold.) The other 50A usually goes to things like HVAC, ignition system, and so forth for the car itself. A 1000 watt class D amplifier is on average, about 80% efficient, so it will draw 100A of current at full output. I think you can see where this is going. On a stock electrical system, you're never going to see anywhere close to the full output of most amplifiers without sagging voltage rails and severe clipping. Now this does lead back to my earlier comments on volume versus power output, too. If you're listening to music, at reasonably loud volumes, you're still not coming remotely close to the full output of the amplifiers anyway so you may be fine with the stock alternator in that situation. 40A of current is still enough to provide up to 400 watts or so depending on the amplifiers, and that can be a lot of "loud."

As for the decibel, and a 3dB change, just look at it like this; 1 decibel is, essentially, the smallest perceptible change in volume to the human ear (this was the original definition) and while the decibel is a log scale, and not linear, you can certainly simulate it by using any radio with a volume "knob" by marking a start position at moderate volume on both knob and bezel, then turning up the colume slowly till you hear a difference, doing this 3 times, then marking the new volume knob position. Now go from first to second mark quickly, and hear the change. That's a basic idea of what a 3dB shift would be.. roughly.

I'm a big fan of the old first gen RE XXX with the XBL^2 motor. I think of the Fi Q series as a development from that subwoofer, since Scott designed both drivers, and both are made to be linear at high excursion, long throw "high output" SQ subs. Like the Alpine type X, while all three subs offer an Xmax of around 28-34mm, they are not by any means designed for SPL, or to be louder than another sub. They're designed for a superior BL curve at high output.

In regards to the large sealed box for the 18, I think at that point I'd seal off the enclosure or trunk, and make the enclosure Aperiodic. You'd lose -3dB in output, but as a trade-off, you'd get amazingly improved driver control, and masked harmonics. It's really one of the best SQ enclosures you could use. Very similar to a transmission line in it's linearity and benefits.

If you want some fun, look at a design like a large enclosure like the one below for a Tempest 15" sub:

LLT (340L -- 12 cubic feet) Tuned 12Hz
This is a large build, using a low tuning frequency and no subsonic filter. This is a design
popularized by Steve Callas of Home Theater Shack fame. It is similar in concept to an EBS
alignment and the general idea is that you use the port extremely low in frequency so that no
subsonic filter is needed. The port is of little value with output >20Hz so most of the
output is handled by the driver, rather than a combination of driver + port in most standard
ported designs. This sub goes deep, but for the 20-40Hz range, it will have less output
than a sub with a higher tuning frequency. For deep in-room response though, the only
competition is from IB subs. If you can live with the size, this is an awesome HT sub that
can plumb the depths unlike any commercial subwoofer available. It will sound less exciting,
due to the loss of output 20-40Hz but if you don't need the extra output, or can build
multiple subs (one in each corner), you can have the best of all worlds. Due to the large
enclosure size the port can also be upsized such that it won't compress as much at full
output. Since the tuning frequency is at 12Hz, most of the output is significantly lower in
SPL compared to the content above 20hz. In most cases, port chuffing is a non-issue.
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 7
Registered: Oct-10
400 watts... that makes me sad. I'm doing the electrical first next time =). My GT was stolen in 2007 but both the XXX and Visonik fried the same week so I switched them out and I still have them. I lost an Atomic APX, thank god.
 

New member
Username: Lord_huggington

Ontario Canada

Post Number: 10
Registered: Oct-10
http://www.youtube.com/watch?v=jR54NXxJSic
 

Platinum Member
Username: Glasswolf

Post Number: 14012
Registered: Dec-03
YT has to be the worst thing in the world for showing off an audio system. The audio *always* ends up terribly distorted. Anyway, I, prior to going to the single Q18, had used two first generation RE XXX 12" subs in an aperiodic enclosure in my car. I'm very familiar with them, although again, I'm more of a SQ guy than an SPL guy, so I never shot any video of the mirrors vibrating. haha

At the time I was using an Alpine F#1status 7990 CD player and DSP in place of the current Pioneer stage 4 unit I have now. I really did like the Alpine. I may even go back to using it eventually.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 865
Registered: Jul-09
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 11
Registered: Oct-10
GW, how much space is the Q18 in? Do you like it more than the XXX V3? Everybody says the Q is an upgrade in everyway, it's just hard to believe.
 

Platinum Member
Username: Glasswolf

Post Number: 14020
Registered: Dec-03
5ft^3, sealed. I like the Q quite a bit. Great detail, tracks quickly, amazing low end extension.
Scott left RE and went to Fi, at which point RE's prices jumped up and they completely changed the design of their subs.
The XXX was an XBL^2 driver. RE gave up the licensing for that technology and changed the motor structure of the sub entirely. The only thing the XXX kept, was it's name.
 

Gold Member
Username: Livin_loud

MW2 Addict

Post Number: 3245
Registered: Jan-06
I ran my D1 Q18 off a RF X7 amp, then switched over to an HDC315. while the AQ is a good driver i still regret the change in setup. the next system i put together will be sure to incorporate another Q (or two). i can't compare to a XXX since i have yet to hear one, but to this day I haven't come across a single sub setup that touches it. amazing the level of low output and how clear it plays it. had it in 7cuft @ 32hz
 

Platinum Member
Username: Glasswolf

Post Number: 14022
Registered: Dec-03
yeah for what it's worth, mine is driven with an Orion 2250SX, bridged mono @ 4 ohms @ 14.4VDC (1200WRMS)
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 866
Registered: Jul-09
Glass, im running a 15'' Q in a 4cuft box @ 35hz. While it does hit the lows nicely im thinking it can do much better. Would lowering the tuning down around 30/32hz make much of a difference or would the difference be minimal? Of course this would require building a new box so.... is it worth it?

(shopvac sorry for the thread jack)
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 12
Registered: Oct-10
Try 5 cubes @ 30hz with around 87.43 square inches of port area. It sounds like a long port though.

http://www.carstereo.com/help/Articles.cfm?id=31
 

Platinum Member
Username: Glasswolf

Post Number: 14026
Registered: Dec-03
do it. I'd tune to 28Hz, myself with a 15"
 

Gold Member
Username: Skibum12189

Cleveland

Post Number: 3267
Registered: Mar-06
WOW.

Either this forum has gotten one million times more educated since my last visit or I stumbled upon a rare (but extremely valuable) thread.

However, Mr. Shopvac, personally, I would go with the ported 12. Plain and simple. Just make sure to take the advice of the people on this forum or build the box to Fi's specs on their website.

I have had one 12 sealed, two 12's sealed, one 15 sealed, one 15 ported, and one 10 sealed. To be quite honest, the 15 was just too big. I had a TC3k and it was a BEAST, but it was just too much. Believe me, I love bass and I loved it's sound quality, but for a daily driver, you're going to want to go with the one ported 12.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 13
Registered: Oct-10
This is the norm at Canadiancaraudio.com, where I'm hesitant to say anything. People over there know way too much about car audio.

When I came over here I noticed it wasn't as number crunchy or knowledgable.

Things like port end corrections for a slot port that has the port running along one (not counting top & bottom) outside wall. Using the 12 volt's port calculator, it will say, for instance, 20" port length = 40hz, while if your port width is 6", it will act as if the port length is plus half of the port width (20+3) because it behaves as if the port is calculated along its center line, yet that calculator measures to the physical port length. It doesn't explain that, and I wonder how many people got the wrong tune?
 

Platinum Member
Username: Glasswolf

Post Number: 14028
Registered: Dec-03
a ported 12" works quite well, and I am a fan of just using one sub when I can. I just prefer to use the largest sub I can reasonably fit into the application, because having the added cone area generally gives better output at low volumes. Particularly with a sealed box. I can have the radio volume at a level that still allows a normal conversation, and still get good bass response, smooth, detailed, and not washed out. With smaller subs they just can't move the needed amount of air to get away with that, and still sound natural. At higher volumes, they do just fine. It's handy to have something like a pre-amp to let you be able to control the bottom octave output too, though... on the fly, that is.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 868
Registered: Jul-09
Id like to do 5cuft but i just dont have the room. The 4cuft box takes up every bit of space i have. So you think 4cuft @30hz would make a difference? Also the box is slot ported,is there any way to change the tuning without building another box? Id like to try it an see if i like it before i build a new one.

Heres a pic of what i have. Any thoughts?

Upload
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 14
Registered: Oct-10
30hz will make a difference. You get your lows back. Rap is no longer quiet sometimes. 5 cubes would give it better lows.

You lessen the port width. Use a calculator. What are the port dimensions?

If your rear seat folds down, I'd have the sub facing into the cabin, maybe on an angle. To get the extra space, use .75" mdf if it isn't already, use less (maybe) port width, and have it go to the back of the car. You have more than 1 cubic foot at the back there, you're using it for loading space which you wouldn't need. I'd seal it off, just think of the gain of that with 5 @ 30. If you can only use the sub when the seat is down, so what?

Is the trunk-cabin cut-out square?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 15
Registered: Oct-10
Use MDF to lessen the port width, clamp it to the outside.

What are the useable dimensions if facing the sub forewards?
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 870
Registered: Jul-09
I really couldnt tell you any dimensions off hand. I do remember the sub had to be firing up cause i didnt have enough height to fit the sub foward. I acually have to take the back seat out an slide the box into the trunk from the inside. Im sure it could go a little bigger,but not much.

The cabin cut-out is square-ish. It has angles in the top corners. Kinda hard to see in the pic

Upload


Idk,maybe I'll mess around with the port to see if i can get it where i want it. Thanks man
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 16
Registered: Oct-10
Is it just me or is your trunk floor on an angle? lol

I'd angle the box, fire everything into the cabin and seal it off for an upgrade. Until then...

Take 2" MDF and stick it into the port along the outer wall. Play with the port length too. Try not to go past 1:3 port ratio, at that point take area off the top & bottom.... or just top or bottom. You might get port noise if there is too little port area. If that Q has 30mm x-max than it needs a minimum of 93.68" of port area to reach full excursion with a 30hz tune. What do you have now?
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 872
Registered: Jul-09
Lol Yea it was at an angle(its an old pic) I took my spare tire out an mounted my amp in there an it left a gap on the one side.

Im clueless when it comes to building/figuring encloseures out. Just horrible when it comes to math in general lol. Im really not sure of the port area. I had a guy on here(bassman) build it for me
( http://dldesignz.com/) It was originally built for a dd1515 then after awhile i ended up going with a Q. When i get a chance i take some measurements an let you know.


Also just curious,how big of a box would i need to run 2 15'' Qs sealed?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 17
Registered: Oct-10
2.5-3 cubes each, depending on if you have the D1 or D2 coil. That'd be a good choice too.
 

Bronze Member
Username: Shopvac

Post Number: 55
Registered: Jun-10
Ok guys, I've decided to go with the Q 12 ported. What frequency should I tune it to?

According to fi the sub is optimal in 2.35 cu ft @ 32 Hz (enclosure cut sheets provided on their forum), would this be good or should I tune it lower? If so, what freq from 28 to 32 is recommended?

I would be building the enclosure my self, after I try to grasp and understand enclosures and tuning, lol...which is my next research/project.

A big "thank you" to all those who have contributed.
 

Bronze Member
Username: Shopvac

Post Number: 56
Registered: Jun-10
@ sean P ... all cool bud, we are here for the same purpose...
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 18
Registered: Oct-10
What are your maximum useable dimensions?

There isn't an audible difference between 30-32hz, more like every 5hz.

I would tune it to 30hz, specifically 29.9, so you can burp a 30hz tone without it unloading.

The Q 12 needs 49" of port area to reach full excursion when tuned to 30hz (29.91 tune & xmax = 49.01).

I would use 1" MDF and do a port 12.5" X 4" for 50 square inches. You need more air space because it's either going to be a super long port and/or too much port area. This is why it's easier to make boxes that work well using drivers with 20 or less mm of xmax. I would suggest the BL 12... it's just easier to get the full potential out of it.
 

Platinum Member
Username: Glasswolf

Post Number: 14033
Registered: Dec-03
"According to fi the sub is optimal in 2.35 cu ft @ 32 Hz"

answered your own question
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 19
Registered: Oct-10
It belongs in 3 cubes for a tune of 30hz, really. 48" of port area with 3 cubic feet = 16 square inches of port per cube, which is also what they recommend (even though it doesn't really matter). They don't go by calculators, and they should. Fi doesn't state that their drivers need either huge ports or huge boxes - it's marketing. You know what happends when you have too little port area and the cone tries to move at a speed faster than what the port allows it to move? Port noise, and expected lower performance. If you want a 32hz tune, you're going to only be using around 20mm of excursion at any time.

What's all this mean? Motor force > xmax.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 876
Registered: Jul-09
Ok help me out here. These are the box measurements. 3/4 mdf w/double baffle

Box width= 29''
Box height= 14''
Box top/bottom depth= 29.75''

Port width= 5''
Port height= 12.5''
Port length= 24''

I just typed in everything using the re calculator. 4.4cuft @31.25hz with 62.5'' of port area. Does this seem right to you? or is there something im missing?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 20
Registered: Oct-10
The RE calculator is bad, don't use it. I use it to give me an idea on the size of a box.

Which way is this firing? I don't know how you got 31.25 HZ, because a 24" long port with a 5" port width is going to act like it's 26.5" port length. The port length isn't 35.37" long (31.25 HZ).

http://www.the12volt.com/caraudio/boxcalcs.asp

29 x 14 x 29.75 = 6.9898 cubes / total space the box takes up

Sealed portion NET space:

Outside box width without port 29-5.75

23.25-1.5
14-1.5
29.75-2.25 (double baffle/add .75 to subtraction)

= 21.75 x 12.5 x 27.5 / 1728 (the constant) = 4.3267 cubes

The 12volt calculator says 4.32671.

Sub displacement .21 (I'm pretty sure?)

= 4.1167 NET @ 35.197 - 35.198

Port area needs 59.99" to reach full excursion, you have 62.5, which is good. Make sure you use a subsonic filter when going over the needed port area... or just always.

15.182 square inches of port area per cube, good.

Port is good. Box good. Good.

Goodbye.
 

Platinum Member
Username: Glasswolf

Post Number: 14034
Registered: Dec-03
"What's all this mean? Motor force > xmax."

heh, yeah Xmax is pretty meaningless in a ported box, since the port induces damping that restricts the travel of the cone anyway.. (cone doesn't move as much in a ported box, as it does in a sealed box.)
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 21
Registered: Oct-10
@ Sean p

You can slant the baffle easily for foreward fire. Even if you sealed it off with duct tape, particle board with leather, and dense blankets, it could be like you had 2 15's (+3dB). All of the annoying trunk rattles would go away too.

If the box height is 14", the bottom of the box needs to be 7" longer than the top, where the angled length is 15.65", the driver cut-out is 15.625", .025" over. The angle is 63.43 degrees.

Can you fit something like that?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 22
Registered: Oct-10
Xmax matters in a ported box below the tuning but that's not its intended use. The bad part is that even when drivers have a lot of xmax (RE XXX), they have lower sensitivity and require even larger ports. Their use is to be able to tune higher without losing the lows, which means you can use them in really small boxes, ported and sealed, and they excell in stupid big boxes. You get more options with lots of xmax.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 879
Registered: Jul-09
31.25hz is what the re calculator came up with so idk. The box right now is sub up with port facing the cabin. I had it facing the opposite way,but it sounds much better this way. I have maybe 3 inches of play at most to make the box longer,thats it. I cant go any bigger than 14'' of height cause my trunk opening is to small from both inside an outside.


I think maybe for now I'll mess around with the tuning on this box to see if i can get it to where i want. Then if im not satisfied maybe I'll break down an get another one. So what do i need to add to the port to get the tuning lower? Lets say 30hz?

Btw,i appreciate all the help man. thanks
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 23
Registered: Oct-10
The RE calculator is way off because of their weird end correction. The 12 volts' port calculator doesn't do any end corrections, so you have to measure from the center line of the port, and it goes on a slant up the wall, that's why you add or minus half of the port width. A physical 24" port length acts like it's 26.5" with a 5" port width. 24+2.5 = 26.5. Easy.

If you can, mount the sub after the box is in the trunk so you can get all the height out of it.

Try a 2" piece of MDF, stick that in the port (the outer wall and clamo it). It should lower it by 2-4 hz. Use the calculator.

Extra space:

5 x 27.5 x 12.5 = .9946 cubes.

You sure you don't have 5" at the back?

I wanna build this box lol
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 24
Registered: Oct-10
Nvm bout mounting the sub after the box is in the trunk... My spacial imaginations are off lol.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 882
Registered: Jul-09
LOL Nope 3'' is all i got to work with. Unless i just leave the whole backseat out? Its just a third car really,but my kids do ride in there sometimes though. I'll mess around with the port tomorrow. See if it makes any kind of difference. Thanks again
 

Bronze Member
Username: Shopvac

Post Number: 57
Registered: Jun-10
hmmm this enclosure designing is more complicated than it really looks....
 

Platinum Member
Username: Glasswolf

Post Number: 14040
Registered: Dec-03
below the tuned frequency is a bit of a moot point anyway since the driver should have a 4th order HPF set at the tuned frequency anyway to avoid the driver unloading.

shopvac; now you know why we professionals get paid to do this stuff, and why labor rates at audio shops are what they are.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 25
Registered: Oct-10
4th order HPF? Don't you mean subsonic filter?

The enclosure isn't tough to design, it's hard to keep all dimensions to within 1/4" for accurate specs.

When you add bracing, the NET space changes, then you have to make the box bigger but the bracing becomes longer too so they take up more space and then you have to adjust the NET space again, and so on. People say use 45's in the corners but I think I'd prefer a thin plastic curve that takes up a lot less space.

How do you know which ends of the box to match up? Use rabbit joints and lock the pieces together that have more force on them (I dunno if it's like that) - the baffle and the back of the box. It's nice to have something to grab onto, but with locking corners you'd kind of have to make the back and the baffle a little longer than they need to be... maybe not the front, because of the port... I dunno.

Yeah... boxes are tough to design and build.
 

Platinum Member
Username: Glasswolf

Post Number: 14043
Registered: Dec-03
>>4th order HPF? Don't you mean subsonic filter?

same thing. 24dB/octave high-pass filter @ the port frequency.
 

Bronze Member
Username: Shopvac

Post Number: 58
Registered: Jun-10
"shopvac; now you know why we professionals get paid to do this stuff, and why labor rates at audio shops are what they are."

I hear ya GW !
 

Bronze Member
Username: Shopvac

Post Number: 59
Registered: Jun-10
"it's hard to keep all dimensions to within 1/4" for accurate specs"

LH, I guess it's too many variables....
 

Platinum Member
Username: Insearchofbass

2 hifonics 2607s, 2dcSounds12xls SPL\idmax12SQ

Post Number: 15704
Registered: Jun-04
Sean p one way to save space is put two four inch aero ports in at stock length (17 inches) with 4.50 cubic feet net and youll have a 28.22 hz tuned box....and yes this will be enough port for up to 1000 watts

ps...build the box yourself this time....it will be worth more than just this build in the end

Going with this amount of port will give you tight upper bass as well as the improved lower bass
 

Platinum Member
Username: Glasswolf

Post Number: 14050
Registered: Dec-03
It's really not that hard to figure bracing and driver displacement if you know the math, and some cabinetry tricks. One simple way to figure bracing is to use a second thickness of MDF the same size as one of the box panels, then just divide it into sections to use for bracing. You already know it's dimensions as a board. Now it's just sliced up.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 26
Registered: Oct-10
^ True dat. I got 27.48 HZ with a 17" long vent though. I dunno about round ports & end corrections. This calculator is way off with slot ports.

http://www.carstereo.com/help/Articles.cfm?id=31
 

Platinum Member
Username: Insearchofbass

2 hifonics 2607s, 2dcSounds12xls SPL\idmax12SQ

Post Number: 15705
Registered: Jun-04
"True dat. I got 27.48 HZ with a 17" long vent though"

thats 2 four inch aeros....you take off an inch for the flare so you go by 16 inches

I used linear team
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 883
Registered: Jul-09
"ps...build the box yourself this time....it will be worth more than just this build in the end"


I would love to,but i just dont have the skill,patience or time to do it. I know...everyone says its easy to do,but for me its not that easy. I rather just tell someone what i want an pay them to do it,that way its done right(hopefully) and looks nice too.

So a question about changing the port width. If i do change it to 3.5'' (from 5'') to get down to 30hz wont this put me below the needed port area? Im having a hard time figuring this out,thanks again guys
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 884
Registered: Jul-09
Also... Would sealing the existing port an maybe adding aeros be an option at all? Or am i just reaching here?lol Thanks again
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 27
Registered: Oct-10
You're already below needed port area, but Fi doesn't recommend going below 12" per cube.

You can seal the existing port, but it would have to be completely sealed.

Your best option is a sealed off foreward fire 5 @ 30, unless you don't want a +4-6dB gain at half an octave lower. You could buy another Q 15 to make up for the lows... or you can seal it off from the trunk. You get the same gain. Since you don't have the space for two.... ;)

I'll convince you!
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 885
Registered: Jul-09
"or you can seal it off from the trunk. You get the same gain. Since you don't have the space for two.... ;)

I'll convince you!"


Ive been considering trying it. Do you have any pics or maybe a diagram that shows how to do it correctly ? I really woulnt even no where to begin with it.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 28
Registered: Oct-10
Easiest thing in the world.

This is what I mean, you just have to measure all of it so that I can figure an angle for the baffle, if you can't fit 15.625" height.. it atleast looks like you can. You need to square off the opening at the highest point, where those pesky corners are. For round ports, 2 6's or an 8" will do (2 6's have 6" more, no big difference). The red is filler, which is like, duct tape & blankets, designed to look cool with particle board with leather stapled to it.

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs882.snc4/71576_499457640785_600705 785_7839463_8094905_n.jpg
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 29
Registered: Oct-10
It wouldn't be a complete seal until you filled the holes in the rear-deck with expanding foam.

This is a poor box design, the ports shouldn't be directly behind the subs, the subs won't load well, although it looks cool.

http://www.diymobileaudio.com/forum/no-question-dumb-forum/91593-sealing-trunk-c abin-question-ported-box.html

The top two pics are my Alero, I was dreaming.

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs884.snc4/71756_499467890785_600705 785_7839731_5603050_n.jpg

Here's a clean one...

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs807.snc4/68764_499470265785_600705 785_7839768_6250356_n.jpg

Here's what looks like your trunk. It isn't sealed, but you get the idea - it's a 12". I believe this is Don Deezy's 152-153 dB RE MT in a neon, loudest neon in that class a couple years ago.

http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs021.ash2/34422_499471575785_600705 785_7839811_4993498_n.jpg
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 886
Registered: Jul-09
"Here's what looks like your trunk. It isn't sealed, but you get the idea - it's a 12". I believe this is Don Deezy's 152-153 dB RE MT in a neon, loudest neon in that class a couple years ago."

Thats what i have, 04 neon.

15.625" height? I can do that. With the spare tire out in the center i have more than enough space. So what happens here...the trunk is just going to act as the box? or am i build the box behind it?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 30
Registered: Oct-10
The best thing about the drivers that have an outside diamter of 15.625 with a magnet cut-out of 14.125 is that 15.625 minus 14.125 = 1.5/2 = .75", perfect for .75" MDF because it's flush. Most 10/12/18's aren't.

If you can give it some more height (15.625 + .75" on top & bottom, for 17.125") so the screws that mount the sub don't go into the adjacent MDF, that's ideal, unless you can off-rotation the sub so the screws don't. A lot of people don't do that, and just make the box the same height as the sub (imagine measuring .625" accuratly - home depot lol) . I don't like to mount the height of the box flush with the driver because if you ever put the sub in/out multiple times, you may have sloppy screw holds/holes after a couple of times. I use a thin piece of foam under the sub mount for an air-tight seal.

If you were to just make a wall and have no box behind the sub, that'd be an IB setup - don't do that. IB setups need subs designed specifically for IB setups. Trunk IB setups aren't "sealed", and it vibrates more. Imagine air moving in/out of every small hole in the trunk - never a set amount of air space, nor a perfect tune.

Therefore, you don't need to remove the spare tire because the box would be square. I've never seen the bottom of a box be cutout to be attached to a fiber-glassed spare-tire area for more space. There has to be like .5 cubes there anyways, not to mention it would require building inside the trunk, which is quite a hassle.

What are the maximum dimensions you can use? 15.625 x ? x ?

You don't "build the box behind it", you simply throw in a box through the cut-out, and since the box is nearly squaring off the opening, the front of the box acts as the wall itself. There is no "wall" building - just a sweet box. Then just throw in stuff around the sides for a seal.

http://www.reaudio.com/speaker_box/LPort_Box_Calc.html

This calc is crap, but it gives you an idea...

5.022 cubes (I didn't calc for .21 displacement) @ 30.01 HZ (tuning would be a little lower with +.75" double baffle).

width 29
height 15.625
depth 1 29
depth 2 29
thickness .75"
port width 4.5"

= 12.7125" port area per cube.

Perfect .
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 887
Registered: Jul-09
I can probly do those measurements,but what im not so sure of are my building skills. lol While id would like to make an attempt at this i just dont see it happening.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 31
Registered: Oct-10
I'll calculate for those outer dimensions and give you the cut-out dimensions for the singular pieces of MDF (home depot can cut to .000", pretty sure). You just have to glue and screw it together, needing wood glue, screws, and clamps. The extra baffle is .75 x 29 x 15.625, I'm not sure about this but you probably just glue it together.

width 29
height 15.625
depth 1 29 (29.75 total)
depth 2 29 (29.75 total)
thickness .75"
port width 4.5"

4.79158 NET @ 32.75 HZ
13.2654" of port per cube

Dunno if that sounds good....

Cuts
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs1158.snc4/150031_499663530785_6007 05785_7844195_5719408_n.jpg

or...

Port width 4.25
4.84778 NET @ 31.6712 HZ
12.3832" port area per cube

Cuts
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs011.snc4/33916_499699475785_600705 785_7845029_5481748_n.jpg

Any less port width and the port area is below 12" per cube.

If you can get the *exact* dimensions I can design you an exacter box =).
 

Bronze Member
Username: Shopvac

Post Number: 60
Registered: Jun-10
Excellent work LH, it's difficult to find this type of info anywhere....
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 32
Registered: Oct-10
Thanks. I've calculated so many boxes this month that now I do them on my cell phone calculator without writing anything down lol.

I'm currently designing the ultimate boxes for an Fi BTL 12, with tunings .1 hz below 30,31,32,33,34,35,36,37,38,39,40. Flared slot port, 45's in corners, perfect everything. I'm going to start selling them as throw-in boxes that'll fit *most* cars - the face being 16.5 x 24, the dimensions for my alero lol. It'll fit the grand prix, grand am, sunfire, neon, cavi, all those small & mid sized trunk cars.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 889
Registered: Jul-09
I'll get you some exact dimensions as soon as i can. I appreciate all the effort though man,thanks. So do you build boxs on the side or is it just a hobby?



"@ sean P ... all cool bud, we are here for the same purpose..." Yes sir we are.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 890
Registered: Jul-09
Ok here we go

H- 15.5''
L- 30''
W- 29''

If there wasnt a metal piece hanging down in the middle for the child safety belt i could do another 1.5 to maybe 2'' more in height. It doesnt look like it comes off very easily either. Thoughts?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 33
Registered: Oct-10
Kinda of late but, what's the driver displacement? I thought it was .21, it might be .19...

.125" under a flush mount? What? How thick is the carpet, .125"?

Check to see if the belt safety metal is screwed in.

The best I can come up with without going under 12" of port per cube is:

.75" MDF + .75" double baffle
29 x 30 x 15.625
port 4.18 x 14.125
4.90964 (with .21 driver displacement) NET @ 31.1024 HZ
12.0258" of port per cube

4.9 @ 31.1 is really close lol!
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 34
Registered: Oct-10
When tuned to 31.1024 HZ, 59" of port area is ideal for a driver with 18.24mm of excursion (Fi BL).

Your Q15 would hover around 18.24mm of excursion (of 28+) at any time (or atleast I think so?) because the cone is loaded more, and you should be able to use more power to get it to reach full excursion. If you get port noise than lower the power. What are you powering it with?
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 891
Registered: Jul-09
Driver displacement is .19 (28mm xmax) . That bracket is welded on,i already checked it out. Im not to sure if i want to cut it out of there or not... Im debating it.

Fi Q 15'' (D2) w/cooling an spider.
Sometimes powered with a aq1200d...
Sometimes powered with a Ed nine.1 Lol
 

Gold Member
Username: Gcs8

Atlanta, Ga

Post Number: 1570
Registered: Sep-09
FI Q 15" (D1) w/cooling and spider being run off a saz-3000D @2 ohms.

/thread jack.
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 35
Registered: Oct-10
*hits forehead*

.75" MDF + .75" double baffle
29 x 30 x 15.625
port 4.19 x 14.125 x 27.155
4.92737 (with .19 driver displacement) NET @ 31.0824 HZ
12.0112" of port per cube
Sealed portion 24.06 x 15.625 x 29.25

4.92 @ 31.08 =)
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 36
Registered: Oct-10
^ which is close enough to 5 @ 30, enough so that you can't even hear a difference.

Cut outs (RE box calculator)
http://www.reaudio.com/speaker_box/LPort_Box_Calc.html
width 29
height 15.625
depth 1 29.25
depth 2 29.25
thickness .75" MDF
port width 1 4.19
port width 2 0

Extra baffle .75 x 29 x 15.625

It says 5.154 @ 28.64, what a dumbass!

Don't bother cutting that seat thing out, there's no point. That box is purrrrrrrrfect.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 892
Registered: Jul-09
Ok,i appreciate it man. I think i may acually give this a shot. Very interested to hear the difference in sound. Question... Do you think maybe i should go with aeros instead? That may save me a little room anyway.
 

Gold Member
Username: Gcs8

Atlanta, Ga

Post Number: 1581
Registered: Sep-09
i use aero's, i like them.
 

Silver Member
Username: Jbpitt

Pittsburgh, Pa. Usa

Post Number: 893
Registered: Jul-09
Also... anybody ever try sub firing down in a trunk?
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 43
Registered: Oct-10
^ good question, I wonder if there's more kinetik energy transfer. If there isn't enough space under the subs, it might act like a crappy bandpass. Kinetik energy = surface area.

You don't need, and shouldn't want aeros, unless you want to switch port lengths for a frequency change, that way you can tune to 30hz and also the resonant frequency for SPL. 4.9 @ 31 is the same as 5 @ 30. Download 30 & 31 hz and try to tell the difference.

The main difference will be when you listen to rap, there won't be a quiet frequency anywhere (maybe less highs like 60-100hz). It will be more musical and have a "fatter" sound that takes up the whole car. If you look at a bassrace song list, the lowest ones go down to about 31hz.

DJ Billy E- Beatz 4 My Van 31hz and a jump to 41hz
The Dream - Luv You Girl 31hz
Gorilla Zoe - Hood ***** 36hz then 31hz
Young Jeezy - White Girl 32 and 53hz
T-pain and Akon- froze ( somewhere between 30-35hz constant)
LiL white- zero tolerance (30-35 hz constant)
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 44
Registered: Oct-10
Three box designs for the new BTL 12, these are all 16.5 H x 24 W x 30 D, all slide in boxes that'll fit into my Aleros cabin-trunk opening (grand am, etc) without having to break anything. 3" baffle, subs sit on 2", 1" everywhere else.

3 @ 31
2.8 @ 34
3 @ 50

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs950.snc4/74299_500705960785_600705 785_7864485_4276143_n.jpg
 

Bronze Member
Username: Lord_huggington

Ontario Canada

Post Number: 45
Registered: Oct-10
2 BTL 12's - 6 @ 34

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs985.snc4/75883_500715375785_600705 785_7864607_99438_n.jpg
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