base tube is 4 ohms... compatible with car electrical system

@Vyas Vishwakarma go for 10 inch as it matches power ratings

Please confirm you are looking for a 4th order bandpass design? Though if you look at the TS parameters of this subwoofer, you will find it is more tilted towards a ported design. A ported box will still give you bass louder and accurate, with peak between 20Hz to 30Hz and a smooth roll off. Below are the TS parameters of Fredo AIT8.4SM/ 8 inch subwoofer:- TS Parameters Qes 0.32 Qms 5.43 Qts 0.30 Fs 30 Hz Vas 80.59 L Electro-Mechanical Parameters:- Mms 52.1 g Cms 540.2 um/N Rms 1.808 Ns/m Re 3.8 Ohms (please check with your multimeter) BL 10.8 Tesla Metre Driver Diameter (Dd) 20.32 cms or 8 inches Sd 324.3 centimetre square Xmax 110mm or 11 cms Physical dimensions of subwoofer:- Thick (Thickness at max circumference) 0.87cms Depth 11cms (Elevated back, here it makes the difference) Magnet depth 2cms (Magnet thickness - single magnet) Magnet 12cms (outer dia) Basket dia 17.78 cms (7 inches) Outer dia 20.32 cms (8 inches) Now you can put all the above parameters in any online freeware loud speaker box calculator programme (WinIsd, WinAmp, XMPlay, DarkWave studio etc) and see the frequency response curves for different box sizes and tuning frequency. Please come back with you decision and we can help you design a box. Watch this space for more info...

You need a seperate box for both recommended subwoofers above

Fredo 8 inch DVC subwoofer will be a good deal for you. You can also go for Fredo 10 inch double magnet subwoofer. Tc....

Power supply and amplifier is inside the base tube. It is an Active base tube. Just need 12V battery connection from the car.

All credit cards are accepted by RazorPay. The payment will go through any bank which has tie up with axis bank. Before you approve the emi on your card, it will show the amount and tenure. The EMI approval is instant. Requires no documentation or phone calls with banks.

Send your mobile number. We can make it available for you. Thanks.

We are original fredo speakers manufacturer's This subwoofer is shipped brand new to the customer. It is on sale @ amazon also for more than 3 years and doing pretty good in terms of customer service & satisfaction.

If you have Fredo 8 inch Single Magnet subwoofer, you may go for either of the first 2 screenshot data which you attached with your question. If you have Fredo 8 inch DVC with you, with double magnet, you may go for the smaller box size as power requirement on amplifier is increased. Please note a bigger box enhances bass characteristics for the same subwoofer. Box size is kept slightly higher if amplifier power is inadequate/less. As you move towards more professional AV receivers/Amps, box size can be reduced by few litres for the same subwoofer size. Hope this explains.

@Ravi Kumar Rao Dear Sir, Thanks a ton for such a detailed and informative write up (with crisp pictures) for the benefit of all audio enthusiasts. Every picture shows your patience and your love & dedication for your hobby. Fredo will support you for all your future endeavors in developing audio enclosures and helping our community. Regards, A.S. Gill.

4.1 stereo audio circuit

Following is the link for Amazon listing which recommends enclosure dimensions along with all the parameters needed. https://www.amazon.in/dp/B0992J7YKR/ref=smop_skuctr_view

Do you wish to make 2 boxes or put 2 subwoofers in one box?

@nirvin kumar Fredo Speakers Retail Outlet will be available in Chennai city shortly.

@Jayant VivYou are welcome to increase volume by 13 litres approx. Consequently, a tad, lower output amplifier will give satisfactory results. Reason being, there's more air behind diaphragm and it's easy to flex it for bass. Do put your efforts for sealing the box with glue and cotton from inside. Tc....

@vijaya prabhu Voight pipe quarter wavelength design for a full range speaker is a good preposition. Following is amazon.in link for Fredo Frd8.8OCNB Full Range monitor we are currently having a discussion about. https://www.amazon.in/dp/B07T1DHJD3/ref=smop_skuctr_view Q mechanical = 3.53 Q elec = 0.76 Leading to Total Q = 0.63 Which theoretically fulfills TPQT requirement of Qts between 0.2 to 0.7, though it marginally misses the BEST recommended range between 0.4 to 0.5 It will be an excellent mid range for Studio Monitoring effect. Giving you a linear/Powerful mid range between 200Hz to 8KHz Later on when you want to experiment with a bigger, more powerful mid range, do have a look at Fredo 12 or 15inch Stage monitor. It will blow your senses and beat any Hi-Fidelity mid range Stage Monitor available in market. Following is the link for Fredo 12 inch Stage monitor https://www.fredo.in/product-page/fredo-12-inch-stage-monitor

@Sukh saab Similar circuit is used in AIT864 Dual Tower Bluetooth Home Theatre. Please refer to the product description below.

Fredo 12 inch stage monitor is excellent mid range for the frequency range specified.

Please go for a professional AV receiver, to get theatre effect. The subwoofer is really power hungry, and solid built. Choose a branded amplifier for any 12 inch or above driver. You may look at Sony (xmn-1004) or JBL as well.