Finaly A Start In The Right Direction...

[MaddoxBay]

Here is a little refresher...

http://caraudiotalk.com/forum//index.php?s...l=dcr+impedance

I should be picking up four of the Tangband's this weekend... Finnaly

NOMINAL IMPEDANCE 4ohm
DCR IMPEDANCE 3.2 ohm
SENSITIVITY 1W/1m 84 dB
FREQUENCY RESPONSE 28-1K Hz
FREE AIR RESONANCE 28 Hz
VOICE COIL DIAMETER 50 mm
AIR GAP HEIGHT 8 mm
RATED POWER INPUT 120 W
MAXIMUM POWER INPUT 230 W
FORCE FACTOR, BL 13.35 TM
MAGNET WEIGHT (50oz) 1427 g
MOVING MASS 95 g
FERRO FLUID ENHANCED No
SUSPENSION COMPL. 333 MN -1
EFFEC.PISTON AREA 0.022 m2
LEVC 3.1811mH
Zo 113.9893ohm
LEVC 3.1811mH
Zo 113.9893ohm
X-max 12 mm
Vas 23 Litr.
Qts 0.30
Qms 10.53
Qes 0.30



I have a Lanzar Opti 1000.1D that I can run them on. I do want to go ported but this is in my daily driver (Pontiac Sunfire) so I still need a trunk.

I would like to be able to get the four in there but i need some help moldeling up a box for these subs. I was thinking 2cuft tuned to 35hz as geolemon suggested. I need to know the port lenght and port area. Building the enclousher wont be a problem but I need all the assistance i can get with the design.

Thanks,

MaddoxBay

P.S. Is DCR IMPEDANCE of 3.2 ohm what you would read on a DMM?

[geolemon]

Sounds like fun!

And yes, DCR is what you'd read on an ohmmeter... just the actual resistive component. It might not be exactly 3.2, but it'll be close.

[MaddoxBay]

Thanks geolemon,

They are reading 3.6 – 3.8 ohms.

The build quality is a lot better that I ever imagined for the price of these subs. I am already impressed with them and I haven’t even played them yet. All the pictures that I have seen of the sub just doesnt do it justice.

Four of these should do well for me. I am trying to figure a way to mount the box to the rear deck and fire them up through the deck and port them through the deck.



thanks

[geolemon]

If you do that, you might be best off completely sealing the trunk from your cabin...
You'll gain 'cabin gain' (no pun intended), and also help eliminate any possibility of cancellations, due to reflected energy going into and back out of the trunk, cancelling against the direct-pathlength sound energy. Sound travels in every direction.

[MaddoxBay]

I don’t think that will be a problem sealing off the trunk. An extra increase in cabin gain was what I was shooting for.

I would like to get the most out of the eights as I could and still sound good.

I have already deadened the trunk some and will deaden the deck like crazy along with the doors.

[MaddoxBay]

What should the air velocity for 35 Hz be if porting straight into the cabin to keep from hearing noise?

[geolemon]

The bigger the ports you can run, the better.
The bigger the port opening area, the lower the risk of port noise.

The actual number varies between software programs... but be a little conservative, if you can.

[MaddoxBay]

In order to get a decent port area I am getting a port length that is hard to work into my plan. I would like to use all four of the subs but if I can’t work this out I might have to cut back to 2 or 3 subs.

Is it possible to stuff a port with a known amount of wool or poly fill to reduce the port length?

Will this make the port act as if it were longer due to the increase in friction?

[MaddoxBay]

Can you check my numbers on WinISD…


4 TB 8’s in a 2 cuft chamber tuned to 29.80 Hz on 400 watts.

3 – 3” ports 29.63” each

Box dimensions: 34.5” (w) x 11.5” (h) x 14.5” (d), after sub and port displacement 2 cuft.


The highest group delay is 20.157ms @ 27.45 Hz. From there it rolls off quick.
The highest port velocity is 21.287m/s peak @ 26.19 Hz.

The Transfer Function Magnitude isn’t flat but a wide curve. -3dB is @ 36.84 Hz. Will the increase in cabin gain help?



Any other thoughts or suggestions?

Would I be better with a 35 Hz tuning?

[fugyaself]

Yes you can stuff a port with poly. Just make sure you have both ends covered with chicken wire or something to hold it in. I havent really seen any calculations or known figures on how much to use to change tuning. Kind of hard to do due to the unlimited sizes of ports you can use to get the same tuning.