advice on audio setup

[michaljerzy86]

so as it is right now, it looks like i'll be getting a set of components for the front, while leaving the rears. i'll be adding an amp as well as a sub
so what i need advice on, is how many channels does the amp need? would it need 3 or do the tweeters need a channel as well, making it need 5 channels?
also...how do i tell how many watts i need from the amp and what role do ohms play?

[Aitch]

1) Your best bet for a flexible amp is a 4-channel setup. Most are ready to go in a 2+1 setup which is what you will be running.

2) The tweeters don't need an extra channel. The front two amp channels power the whole front stage (one channel per side) and the signal is split by the front component crossovers to the mid-range speakers and the tweeters. On a single-amp setup there is no need to power the tweeters separately.

3) Most components are going to be 4-ohms. This is the electrical resistance of the speaker system. At lower resistances, an amp can usually provide more power (and the speakers can handle more). There are a few speaker manufacturers who use 2-ohm speakers as well, check when you're shopping.

3a) This is a benefit to the 4-channel amplifier. When buying the amp you have to consider the power levels of the channels for the fronts (at 2 or 4 ohms) as well as what the rear channel power level is when bridged (i.e. the sub is run on both rear channels at once). When you bridge the rear channels they are almost always run at 4-ohms (make sure your sub is configured to run at this resistance) and aren't stable at 2-ohms. However the front channels are unbridged, and free to run at either 2 or 4-ohms, depending on your front speaker choice. Again, great flexibility.

4) Now you're beginning to see how many factors you have to consider when designing your system, even with basic components. Your best bet is to figure out what power range you want to be in for either your sub or components, then find an amp that matches that range, and then finally match the remaining part (components or sub) to the other half of the amp. Don't be afraid to get some power in there, but by no means does it have to be extremely high.

My example: I'm running Alpine Type-X 6.5" front components (soon to be replaced) rated at 75WRMS I believe, and an Image Dynamics ID12 sub rated at 200W RMS. Currently they are a little underpowered by an Alpine MRP-F300 4-channel amp (50W RMS @ 4ohms to the fronts and 150W RMS bridged @ 4ohms to the sub). Ideally I'd like a bit more power there but in real life, the system is capable of playing louder than I want 95% of the time, cleanly. So overwhelming power is not always necessary.

Happy hunting!

[michaljerzy86]

awesome info, you're a good help!
so how would an 8'' sound compared to a 10''?
cause i'm thinking of just getting a stealthbox for the carjack and it'll only fit an 8''

[Aitch]

Well I know that the difference between a 10 and a 12 is usually that the 10 is a more crisp sound while the 12 feels like it has more power behind it. If you don't feel you need to really feel the bass in your gut then I think an 8 would suffice. I had a 10 in my first car and it did pretty well but I like having the 12 when you've got the space available. Its all personal preference.

[michaljerzy86]

alright so lets say i get the 4 channel amp, a sub and some comp's up front. i know i need an loc to connect it to the factory hu but after all of this am i still only going to be stuck with the bass and treble +/- 6 options? i know there are processors but this is already getting pricey.

[Mty Mous]

alright so lets say i get the 4 channel amp, a sub and some comp's up front. i know i need an loc to connect it to the factory hu but after all of this am i still only going to be stuck with the bass and treble +/- 6 options? i know there are processors but this is already getting pricey.


As for amps, yes I agree with Aitch's idea of going 4-channel, but if you can find a 5-channel amp, it'll really go a long way, especially if you plan to bi-amp your components (this means running seperate amplified channels to your tweeters and midrange speakers up-front) or if you decide you're rears aren't loud enough off the deck's power, and you wanna amp them too.
You can do all that while still having a dedicated sub channel with decent power.
One amp that comes to mind would be something like the Alpine PDX-5. Its a bit pricey, but if you're thinking about a sub enclosure that hides in the jack's compartment, the I'm assuming you'll wanna occupy minimum amounts of room, and the PDX-5 is pretty darn small! :)

Anyways, just throwing another idea out there for ya.

As for sound processing ... what kind of budget are you planning on spending on that? That would aid in what kind of solution you should look at.

[mdass52]

If you're going to go with a 5 channel amp, I would not suggest the PDX-5. It lacks in the sub channel. Go with something like the fosgate power 1000. It has more then doubel the power to your subs. I'll be upgrading to one of those in the near future. The PDX-5 is smaller and is more efficient but it all depends on what type of bass you're looking for as Aitch said.

[forbidden]

You are far better of going to a interface adaptor over a loc in this situation. The worst thing in the world you can do is mess with the bass control and have it affect all speakers in the system. A interface adaptor, like the Audio Control LC6i is going to provide you a dedicated sub out with a dedicated level control for it. This is going to allow you to fine tune the level of bass response separate from the main speakers.

Your choice on amp is going to be limited by a number of factors. Power you think you need, space, budget for example. A 5 channel amp is a ideal amp for a person who is looking for a good system that is not going to rip his ears off. Boston Acoustics makes a great 5 channel amp, Eclipse used to as well. Lots of options to consider but I would want way more info before I settled in on anything as a solid recommendation.

[Aitch]

Although a 5-channel amp has even more flexibility, considering you are looking at an 8" sub I wouldn't expect you're looking to separately power your front mids and tweeters. So I still would look at 4-channel amps (and there are more options on this front, probably a bit more economical as well).

Forbidden is right about the LOC. While they are a great inexpensive option, not being able to adjust the bass control without affecting all components can be a pain. I lucked out and found an older MTX crossover, which had speaker level inputs (fed from the headunit) and then outputs both signals for front and rear independantly. The head unit bass control can still affect the sub level, but I have a remote gain knob that equals things out. However, now that I've got things set I don't mess with the head unit bass controls much, just the sub control.