Audio help

[billybunter]

Hi to everyone, this is my first post on this site. I just have a few questions that im hoping that some people can answer for me as it will help me a great deal.

I'm just going to do a Audio install in my car (focus hatchback) and I thought I would come on here and ask the question to make sure Im not going wrong anywhere.

My plan.....

custom sub box (not doing this my self but im having it made by a carpeter i know) not sure if I should get a ported one made or not??..

2 * 15" subs.....Fli subs each 400rms peak power 1200 each

specs;

* 15" FLI subwoofer

* RMS Power: 400 watts

* Peak Power: 1200 watts

* Sensitivity: 90db

* Frequency Response: 20 - 850 Hz

* Impedance: 4 Ohm

* Mounting Diameter: 350 mm

1 * KENWOOD KAC 9104D MONO 1channel car amp amplifier 1800W ( To power the subs )

specs;

# Rated power (4 ohm, 20 ~ 200 Hz, 0.5% THD) @ 14,4V : 500W RMS

# Rated power (2 ohm, 100Hz, 0,9% THD) @ 14,4V : 900W RMS

# Rated power (1 ohm, 100Hz, 1,0% THD) @ 14,4V : over 900W RMS

# Maximum output power @ 14,4V : 1800W

# Aluminium Die-cast heat-sink with Aluminium dress-plate

# Power MOSFET Switching Power Supply

# 1 ohm load capability

# Gold plated RCA Line in & output

# Gold plated terminals

# Plug-type Speaker Level Input

# Dual Mono Drive

# Copper EE-Core Power Transformer

# Toröidal Noise Suppression Filter

# Ground Isolation Circuit

# Variable built in low-pass filter (24 dB/oct.): 50 ~ 200 Hz

# Infrasonic filter (18dB/oct.): 0/15/25 Hz

# Variable Bass Boost (Variable gain): 40Hz, 0 ~ 18 dB

# Variable input sensitivity: 0.2 ~ 5V

1 * Fli Loaded 900s 900 4 Channel 900w ( to power 2 sets of 5*7's)

specs;

Type: 4/3/2 Channel.

Class: AB.

4 Ohm Stereo: 4 x 100W RMS.

2 Ohm Stereo: 4 x 115W RMS.

4 Ohm Mono: 2 x 225 RMS.

2 Ohm Mono: N/A.

Max Power: 900W.

Frequency Response: 20Hz-20KHz.

SNR: 92dB.

THD: 0.2%

Bass Boost: 0-12dB.

HPF: 45Hz-300Hz.

LPF: 45Hz-300Hz.

Input: 2 or 4 Channel.

2 * door speakers Top spec with 90db sensitivity and a massive 300W (150w rms) power output

1 * 2000w Amplifier Wiring Kit

1 * car stereo 2.0 digital power capacitor cap

1 * 5 Meter Clear OFC Speaker Cable 2.5mm2 14 Gauge wires (Got told to use these on the subs)

1 * Pioneer p910bt headunit

My questions are;

I know what size of sub box I need but should I have it ported or just enclosed? if so what sort of size should it be?

For this sort of setup would I neew to upgrade my alternator? (I have stock)

I also got told that I should wire my subs as follows;

possitive from amp to possitive sub 1, negative from sub 1 to possitive sub 2, then negative from sub 2 to negative amp....is this the best way?

How could I find out what sort of gains I should put up on the amps without damaging the speakers or amps?

With the wiring kit I mentioned above I will be wiring it two a splitter with fuses in so i can wire both amps from there....what sort of fuses should I use in the splitter and what size wires should be used to connect each amp?

I have done a setup before But I want to make sure that Im doing it correctly and the best way. If I have missed anything then if you could let me know that would be great.

As I have said I have done an install before but I still feel like a total newbie.

I know I have thrown alot of information in but I tried to cover everything so sorry if most of it is no use...

Thanks in advance for any help thrown my way....

[crazyfrazz09]

first step- dont but that 2.0 cap its a waste of time if you need more on tap gat a 2nd battery and upgrade the one under the hood. and this will help with your wireing http://www.the12volt.com/caraudio/woofer_configurations.asp?Q=2&I=41 find out what size wire your amp will accept and use that from your distrobution block (splitter) to the amps and run 1/0 from your front battery to your back one. this will allow you to be able to upgrade later when you go bigger!

[sven6977]

Stock alt will probably be fine, maybe do the big three.

for the wiring, you wanna run it parallel, not series (which is what you described) parallel is hooking the positive (+) from amp to first sub, then the + from the first sub to the +of second sub, then the negative (-) from amp to - of sub one, then the - of sub one to - of sub 2. This way, you will end up with a total load of 2ohms. That way your amp is putting out 900W which is just over the total Watts needed for your subs (100W over).

To find the gain you need on the amp, first don't use any bass boost, it distorts the signal and often causes clipping IMO. Second, hookup the main power and ground lines to your amp and the remote wire so it turns on. Then use a multimeter and set it to AC and attach the leads from the multimeter to the speaker outs on your amp. On your head-unit you should play a test tone track that loops a tone anywhere from 40-60Hz. (theres a lot of debate about whats the best frequency to use). To find the correct voltage you need your multimeter to show, you use ohm's law to calculate the numbers. (I=V/R)

however, you change the equation so that you get I*V=V^2/R or W=V^2/R, then alter it so you get sqrt(800W*2Ohms)=Voltage needed=40V. So what you do is adjust the "gain" or "level" knob (i dunno what it will be labeled on your particular unit) until your multimeter reads that number.

OR

You could just set it by ear. Adjust your gain until your hear some clipping then back it off until you don't hear clipping anymore lol

As Per the fuses, The way I understand it is that you want the fuses in between each electrical component to be just a little greater than the fuses used in the device. So say you have one amp that uses a 100A fuse and the second one uses a 60A, you would wanna use maybe 200A in between the two amps and the battery. However I'm not positive about that. (Someone Correct me if I'm wrong).

Next time though, try not to write a book.

[billybunter]

first step- dont but that 2.0 cap its a waste of time if you need more on tap gat a 2nd battery and upgrade the one under the hood. and this will help with your wireing http://www.the12volt.com/caraudio/woofer_configurations.asp?Q=2&I=41 find out what size wire your amp will accept and use that from your distrobution block (splitter) to the amps and run 1/0 from your front battery to your back one. this will allow you to be able to upgrade later when you go bigger!

Right, cheers for the info. I will get a second battery and use that one to power my amps and stuff. Ill sell the 2.0 cap.

Can you hellp with the other questions.....quite interested about the port hole

[billybunter]

Next time though, try not to write a book.

Ha ha ha,yeah that is noted just wanted to make sure I didnt leave anything out that was needed.

Thanks alot for your help guys.

[sven6977]

Ha ha ha,yeah that is noted just wanted to make sure I didnt leave anything out that was needed.

Thanks alot for your help guys.

no problem, If you want more info on the ported versus sealed, you should check out the Subwoofers/Enclosures section of the forum. linky

[billybunter]

what sort of battery should i get?

never done this before..I guess i would get two one for the boot and one for the front..

[crazyfrazz09]

you have a few options here. you can buy some of the ones that have sections here on this site and get bigger than you need (so if you upgrade down the road you wont need to worry) or go buy a few bigger batteries from your local auto parts place.

[billybunter]

you have a few options here. you can buy some of the ones that have sections here on this site and get bigger than you need (so if you upgrade down the road you wont need to worry) or go buy a few bigger batteries from your local auto parts place.

Well cool, ill have a look in to that. considering im in the UK i wont be using the link. it would cost me more.

thanks for helping the limey :-)

[crazyfrazz09]

lol, no problem mate