audio help

[napkinthief]

first of all does anyone know a website where i can learn about setting up my own system i know the basics, headunit to an amp then amp to subs, spread the wiring from both sides of the car to block interference, and the right size box is the only way to get good sound out of a sub

1 is it a problem is the amp has more watts than the subs combined
2 is a 2 channel sub not good enough for 4 subs
3 how many watts is enough for a good thump but i dont need crazy window shattering sound

 

[Chuckster]

http://www.bcae1.com/

A plethora of information there.

 

[gsx951]

1 is it a problem is the amp has more watts than the subs combined
No problem and actually it's what you want.


2 is a 2 channel sub not good enough for 4 subs
You can configure wiring in many ways to arrive at an impedance the amp will be happy with. http://www.rockfordfosgate.com/rftech/wiringwizard.asp


3 how many watts is enough for a good thump but i dont need crazy window shattering sound
This depends on the efficiency of the sub. A sub that is 90db or better needs just a modest amp but one that's only 85db will require much more power. Keep efficiency in mind when shopping. I run a single 12" dual voice coil speaker with a 1985 Punch 150 amp and it's all that I need.
http://imagedynamicsusa.com/tech_page.php?name=IDQ12D2 V.2&type=sub&id=idq

Here's a great place to lurk and learn: http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi

 

[napkinthief]

ok nice, and about power caps....1 farad = 100 or 1000 watts? my friend has a 1200 watt amp and 2 300 watt subs with a 1 farad cap, but his lights still flicker is it because the amp takes 1200 watts?

 

[gsx951]

Go back to the link that I posted and search Richard Clark's column. Rich was a big proponent of caps back in the days of Autosound 2000 and the GNX but has backed away.
Most caps aren't fast enough to be effective at all because of internal resistance.

 

[drivemusicnow]

First.. Caps do nothing. Unless you spend a LOT of money on a slow release capacitor (which are not typically the ones sold on car audio websites) they don't do shit. So don't worry about it.. the only way to get your lights to not flicker is to have an alternator that can produce however much current the car needs+whatever you're audio is pulling at the low RPMs..

Second. Box has to be built to the subwoofer specs.

Third do more research before you buy any component of a car audio system.
You're considering 4 subs for some reason.. and unless you're really just trying to get your bling on, thats retarded. A Single GOOD 12 in a ported box (CORRECTLY BUILT) will produce MUCH cleaner, MUCH louder bass then 4 mediocre or crappy subs. plus it will usually take up less weight, use less power, and be more efficient overall

Fourth, as far as sub and amp power recommendations go you need to understand how subs and amps are rated. Cheaper subs and amps are rated at PEAK power ratings. This is basically a bullshit made up number that is usually double of the "RMS" or your "constant" power rating. basically a number given at peak power is twice as large as the number you want to consider. SO if your sub is rated for 400 watts peak power. it really only wants 200 watts. if your amp is rated at 1200 watts peak power, its really only putting out 600.
However it gets more complicated. These power ratings are at specific resistance loads, in ohms. If you amp is rated 1200 peak power at 1 ohm, and your sub is only a 4 ohm single voicecoil, then you are taking that 1200 dividing by two to get your RMS power, then dividing by 4 to get the power that it would actually send through the sub. leaving you with 150 watts pushing that sub.
Different wiring setups with multiple subs, or dual voicecoils can change this around a bit. I'd suggest going to crutchfield to see their wiring setup guides.

As far as CHANNELS go, a channel is left/right. because bass tones are mono directional, you don't need stereo channels for subwoofers. so depending on the amp you can sometime "bridge" the two channels together to provide one, higher powered channel. Some can do this, some can't. If you can bridge the amp (this time lets pretend its a 400 watts by 2 channel amp peak power) and you have 4 subs all with 4 ohm voice coils. then you have to make sure you won't blow your amp up. Because you are wiring multiple subs together, you have options as far as what your "End resistance" will be. if you wire them all in series, overall resistance will be 1 ohm. if you wire them 2 series of 2 parallel, then your resistance will be 4 ohms.

Depending again, on what type of amplifier you have, it will have a limit to how "low" the overall resistance can be. usually on a 2 channel bridgeable amp, it is a 2 ohm limit. therefor you would have to wire the subs in a 2+2 fashion, and end up with a resistance of 4 ohms.

So you take that 4 ohms, and that 400x2 amp and you do some math.
divide your 400 peak by 2 to get 200 watts by 2 of RMS power
take your 200 watts per channel and combine them, so you get 400 watts by one channel,
and depending on what resistance the original power (most likely 4 ohms) you divide by the difference between what the amp is rated at, and how much resistance the subs are actually wired to. In this case, if the amp is rated at 4 ohms, and the subs are wired to 4 ohms, you divide by one, and end up with 400 watts to all 4 subs, or 100 watts per sub.

blah that took forever... hopefully it helped.

Oh and www.bcae1.com is an amazing reference site. and you should spend a lot of time on it and car audio forums before making any purchases.

 

[gsx951]

but his lights still flicker is it because the amp takes 1200 watts?

The DSM alternator is only good for 90 amps..... My little PPI A600 will draw 94amps at full load.
A stock charging system can't hope to keep up with 1200 watts.
That's really the thrust of my "keep your system efficient." argument, you can easly build a system that will require an expensive H/O alternator and multiple batteries.

 

[napkinthief]

wow thats a great write up, would make a nice sticky or an article in the guides. yea i started reading that site last night lots of info, but its good i learned about the ohms and stuff and the caps are useless.

as a dsmer what kind of alternator options do i have?

also, if i get an amp that is enough for more than 1 sub, than get 1 sub now and more later on if i feel the sound is not enough, would there any issues or would i just have to change the wiring around?

 

[timm98gst]

http://www.caraudiohelp.com/

 

[Attack Eagle]

1 is it a problem is the amp has more watts than the subs combined
No problem and actually it's what you want.


2 is a 2 channel sub not good enough for 4 subs
You can configure wiring in many ways to arrive at an impedance the amp will be happy with. http://www.rockfordfosgate.com/rftech/wiringwizard.asp

Just remember that if your subs are rated for example for 200w RMS each, then you need an amp that will provide 800W RMS at the impedence you wind up with.

YOu might for example get 800W at 1 ohm at the amp, but then each sub would only get 1/4 of that power... In this case you would want 4 ohm single coils or 8 omh dual coils,
wire the 8 ohms in parallel so you wind up at 4 ohms per sub, then wire all 4 in parallel to wind up with 1 ohm.

 

[gsx951]

wow thats a great write up, would make a nice sticky or an article in the guides. yea i started reading that site last night lots of info, but its good i learned about the ohms and stuff and the caps are useless.

as a dsmer what kind of alternator options do i have?

also, if i get an amp that is enough for more than 1 sub, than get 1 sub now and more later on if i feel the sound is not enough, would there any issues or would i just have to change the wiring around?

Search around for vendors, the H/O alternators are nutty expensive. You can also get stock units beefed up by your local re-builder-check the phone book.
Your best bet is to plan things out and be rational in system design. You can put together a loud ass system and still run a stock alternator. Remember speaker efficiency is key here. Those numbers in the speaker spec. sheet are very important. A sub that's rated at 87db is going to need TWICE the amp power to play as loud as a 90db speaker!
You can endlessly reconfigure your wiring as your system grows but as it's been suggested, a single 12" will really get the job done.
Continue to read and then develop your system plan.

 

[napkinthief]

Ok I just picked up a 12" Sony Xplod XS-L1236 off ebay for 35$.
300W RMS, 900 max
89 dB
1 cu ft sealed box
4 ohm independance
link

I will be making my own box because I do have very decent skills in wood working. Going to pickup some MDF right now.The box recommended is 1 cu ft, so if the board is 3/4 the dimensions should be 12 3/4 inches each width height and length

now I need an amp, but I will probably be looking to expand the system later on, should I get an amp that pushes 300 rms right now, and then just get another sub and amp later on, or spend the $ on a 600 rms amp

 

[napkinthief]

also if i bridge an amp down to 1 ohm for 800 watts and the sub is 300 watts would i only be getting 200 watts from the amp (800 / 4 ohms)?

 

[drivemusicnow]

If the amp is a 2 channel amp, that has PEAK power ratings of 400 watts per two channels then if you were to bridge it, you'd be getting an actual 400 watts at 2 ohms (usually)
The sub is 4 ohms, so you'd only be getting 200 watts of that power to the sub.

If you have a 800 wats peak power MONO amp then you're sending 400 watts RMS at whatever resistance load it the amp specifies. if its "800 watts at 1 ohm) then you would only actually be getting 100 watts to the sub.

 

[gsx951]

If the amp is a 2 channel amp, that has PEAK power ratings of 400 watts per two channels then if you were to bridge it, you'd be getting an actual 400 watts at 2 ohms (usually)
The sub is 4 ohms, so you'd only be getting 200 watts of that power to the sub.

If you have a 800 wats peak power MONO amp then you're sending 400 watts RMS at whatever resistance load it the amp specifies. if its "800 watts at 1 ohm) then you would only actually be getting 100 watts to the sub.

There in lies the beauty of DVC.

 

[Attack Eagle]

Ok I just picked up a 12" Sony Xplod XS-L1236 off ebay for 35$.
300W RMS, 900 max
89 dB
1 cu ft sealed box
4 ohm independance
link

I will be making my own box because I do have very decent skills in wood working. Going to pickup some MDF right now.The box recommended is 1 cu ft, so if the board is 3/4 the dimensions should be 12 3/4 inches each width height and length

now I need an amp, but I will probably be looking to expand the system later on, should I get an amp that pushes 300 rms right now, and then just get another sub and amp later on, or spend the $ on a 600 rms amp

If you get an amp that pushes 300w rms @ 4 ohms, when you add another 4 ohm sub you will drop to 2 ohms and get 600 w/2 so still 300w each .

 

[gsx951]

If you get an amp that pushes 300w rms @ 4 ohms, when you add another 4 ohm sub you will drop to 2 ohms and get 600 w/2 so still 300w each .

Feel free to correct me if I am wrong but in a parallel circuit, wouldn't there be 600w across all of the drivers?

 

[TSIMonsteR]

like stated above, your sub is 4ohms, so get an amp that is 3 or 400wrms @ 4 ohms and when you add another 4ohm sub to that same channel, your amp will only see a 2 ohm resistance, therefore you'll get 400wrms to each sub due to less resistance.

http://www.cardomain.com/item/SONXSL121P5 and click on subwoofer wiring guide link.

check that out, it will show you how to wire almost any sub to an amp.

Based on what I have read, and since you already have a sony sub, an amp like this would suite you well. (you could find it on ebay)

http://www.cardomain.com/item/SONXMD6000GTX

 

[Attack Eagle]

Feel free to correct me if I am wrong but in a parallel circuit, wouldn't there be 600w across all of the drivers?

Right, from the amp's perspective acrossthe entire load there woudl be 600watts, but if the drivers were of equal impedance and identical drivers (impedence changes with excusrsion IRL) then they would each recieve an identical amount, ie 1/2 or 300 w

 

[Winky]

i have always been told to have about the same wattage as you do rms in your speakers with the amp.... maybe a little bit more.

i've seen this guy with 3 mojo memphis audio subs in his car and didnt shatter .... although his roof did shake. (so much power)


oh yea crutchfield.com has tutorials on various things... best bet in my opinion is to do a search on google


yea ask more if you need more (i probably didn't help but thought you'd like to know this anyways)

 

[DROOPY209]

I will be making my own box because I do have very decent skills in wood working. Going to pickup some MDF right now.The box recommended is 1 cu ft, so if the board is 3/4 the dimensions should be 12 3/4 inches each width height and length

keep in mind your subwoofer is also gunna take up some space inside that box.
might wanna make the box a lil bit bigger to compensate for the space the speaker will take up.

 

[Winky]

or invert the speaker.... one or the other

 

[Winky]

or invert the speaker.... speaker inverted = less space needed... and it will sound the same i promise

 

[DROOPY209]

i have always been told to have about the same wattage as you do rms in your speakers with the amp.... maybe a little bit more.

Sorry but thats not true pal, it depends how efficient the amplifier makes the power.
65% efficiency is not good at all.


I have a MMATS 12" 600 watt rms in a ported box tuned to 33Hz with a old school rockford fosgate amp with 1 channel rated at 200 watts rms.

Ask anyone that has heard it personally, it hits, and it hits HARD!

you dont need a lot of watts to be loud. you need clean efficient wants and a very well designed box.

 

[DROOPY209]

or invert the speaker.... speaker inverted = less space needed... and it will sound the same i promise

Keep in mind that you will have to wire the subwoofer speaker leads backwards, as the subwoofer will be pushing the air inside of the box when it should be at its excursion outwards into atmosphere. your bass will be off.

people will be able to see your cool sub, and stuff in your trunk will be hiting your sub, especially small metallic objects will eventually get trapped in the subwoofers cone, seen that happen many many times to people.