Cars Resonant Frequency.

[Ray]

Just shrink the last one a bit.

1.6 max.

[hawkei67]

So does this one look right? Would it hit harder than the current old-a$$ radio shack csw-800 8" subs in the sealed box? I hope I am understanding the results currectly, that is my main problem. The maximum Normalized amplitude Response was 8.24dB at 33.76Hz with a gradual drop to the 3dB point of the HF end which was at about 54Hz and the 0.97dB started at 71.17Hz on the HF end and stayed pretty much close to that level throughout the rest of the HF band, while on the LF end it drops rapidly from it's peak of 8.24dB at 33.76Hz to it's F3 ending around 15.64Hz and continues to drop sharply from then on down. The Custom Amplitude Response shows a maximum dB level of 117.2dB at 33.76Hz. The cone displacement and vent velocity look pretty good too. By the way, I can shorten the vent down to a diameter of 3 inches and a length of 9.33 inches and the box still tuned to 32Hz with the same dB results on the Normalized and Custom Amplitude Response screens while the Cone displacement and Vent Air Velocity are still at a safe level if need be. You let me know what you thin of this one and if it is worth the effort and material.

Driver Properties

Name: db10 (4 ohm)

Type: Standard one-way driver

Company: Polk Audio

Comment: DB Series

No. of Drivers = 1

Fs = 26.7 Hz

Qms = 4.91

Vas = 44.9 liters

Cms = 0.24 mm/N

Mms = 148 g

Rms = 5.058 kg/s

Xmax = 8.7 mm

Xmech = 25.4 mm

P-Dia = 215 mm

Sd = 363 sq.cm

P-Vd = 0.316 liters

Qes = 0.409

Re = 3.7 ohms

Z = 4 ohms

BL = 15 Tm

Pe = 300 watts

Qts = 0.376

no = 0.201 %

1-W SPL = 85 dB

2.83-V SPL = 88.54 dB

-----------------------------------------

Box Properties

Name:

Type: Vented Box

Shape: Prism, square

Vb = 1.57 cu.ft

Fb = 32 Hz

F3 = 15.64 Hz

Fill = none

No. of Vents = 1

Vent shape = round

Vent ends = two flush

Dv = 4 in

Lv = 18.14 in

[Ray]

That one is the winner..

Still use the 4"....dont shrink down to the 3"

Sure its worth the material

Go build it

[hawkei67]

Good deal, now the question of the sub placement and vent placement. Should the vent go on the same side as the sub? Is 18.14" a little to long for the 19" depth, (it will only be 7/8" of space between the back wall on the inside of the box and the end of the vent) is that safe with excellent pounding bass and no problems?. The reason I ask about the vent length and where to place it is the fact that I read somewhere else that your port should be the same distance from any walls as the diameter of the port (that would be 4 inches from any wall) and if I place the sub on the same portion of the box as the vent then isn't there a rule of thumb that the sub should be so far away from any ports depending on the port diameter? I would like to have the sub in the center of a 14 x 14 portion of the box, that would give me 2" space between the outer edges of the sub and the walls of the box (is that right?). It is 14" Height x 19" Wide x 14" Depth. Where should I place the sub and where will the front of the sub be facing? Where should the vent be placed being as long as it is, should the vent be facing toward the passenger area or the rear of the trunk or up toward the rear deck where the 5x7's are or out one of the sides facing toward one of the fenderwells? Thank once again for all the help and being patient with me. This is very appreciated. Do you think this will be a better box, sound good, hit hard with some good vibration than the 2 current Radio Shack 8" CSW-800's that are in a sealed box in my car?

[TeamHT]

I'm really sorry, I stopped reading and paying attention when you said "the amp is turned up about 3/4 of the way"

[Ray]

You need to go look at build logs for a day

[blownengine]

I'm really sorry, I stopped reading and paying attention when you said "the amp is turned up about 3/4 of the way"

I stopped reading when I saw that every one of his posts were like 4 page essays

[hawkei67]

lol at blownengine, I know I go a little overboard with my posts but I just want you guys/gals to know what I am see-ing on the response graphs. My posts do seem a bit retarded, now that I look back at them, by mentioning every little detail. Once again sorry about that...lol.

[hawkei67]

I know this is a lot more downscale than what you guys/gals are used to designing, building and testing (no where near the wattage or quality/quantity of subs or exotically designed) for competition or regular daily driving tuning. And yes I do go way overboard on the information, but that is just how I am and I apologize for that. All I really want is just a better (better sounding bass, hardest hit possible) box for maybe a different sub which I have laying around that is a little bigger than the 8's and has better power handling capability - Polk Audio db104 10" 4 Ohm(hardly any use on it at all, practically still brand new) or maybe the old cheap radio shack 8"s using the same radio/amp but better and harder hitting bass with some descent vibration. I know this seems so simple that an idiot could do it to a lot of you guys/gals but for a newbie like me it is a lot harder for me than it is for you all, so please just bare with me. I love this site and love looking at the other designs and builds but I have no understanding of how you all came up with such beautiful and awesome box's. I would just like a simple hard hitting but great sounding box better than what I believe I have now using the materials I have at hand and radio/amp with only having to pay for the MDF cutout one time. Thank you all for the help and may God Bless each and every one of you!

[kr15]

Ray is a very respected car audio figure in our region, his info is probley on point as it gets when it comes to box design..take his advice without reservation