Amp questions

Hey all, new poster but have purused the forums for a cpl years. I finally bit the bullet and decided to upgrade my non JBL, dbl cab stereo system. I'm about half way through, am now realizing I may have needed to spend just a bit more time in the researching phase but oh well.

Atm I have kenwood ddx419 HU, alpine type R 6.5 comps in the front and 6.5 coaxials in the back. HU was purchased and installed at one local store in San Diego-600ish dollars, and speakers at another 600ish. Ack, next time I'm buying separately and installing myself. My next step is an arc audio 12, w/ mr.marv enclosure, raamaudio dampening, and a yet to be named amp for the sub and the components.

My research into amps hasn't gotten me very far, if anything just more confused (btw amp is going under driver seat). I believe I want to be around 75wx2, and whatever it pumps out to sub.

I know my alpines are 4 ohm, not sure about my sub yet. When I read specs on amps it gives ratings in 2/4 ohms. Which leads to first question, can an amp push 4,&2ohm speakers at the same time or does the amp get set to a certain ohm setting and you have to match your speakers to that?

Easy one... Where do I ground my amp?

Another, what should I be looking for, are class d amps better? Is a bass knob good to have? What type of pricing should I be looking for? Are there brands I should stay away from? Do I need to run 2 sets of rca cables?

I may have more questions later but if anyone can help me out with some of these that I came up with while window shopping today it'd be appreciated. I really don't want to be super impulsive and spend 400 bucks on an amp if one that is 150 will accomplish the same thing, I'm not an audiophile just like a clean sound that doesn't make me want to drive around with mute on all the time.


Thanks, sorry for the long un-organized post

 

I am not quiet as technical as some of the guru's on here but I will try to help you out. First question, your amp sees the load that is put on it. (1)4 ohm sub will pull 4 ohms from an 1 channel(mono) or 2 ch (bridged) amp. If you have (1) 2 ohm speaker it will draw a 2 ohm load from the amp. If you have a 4 ohm Dual voice coil sub it means it has two sets of connections and acts like 2 single voice coil sub woofers and when wired will either put a 2 ohm load or an 8 ohm load on a mono(1 ch)amp(series or parallel)

You want to stick with a class d for your sub amp, class a&b for front channels(if you want to put an amp to your front speakers).

2nd question. Ground to one of the bolts going into metal chasis(seatbelt bolt, ect.) I screwed my own ground to the metal floor after sanding paint off (with self tapping screw).

Bass knob is must Bass goes up and down with differnt songs, this offers a really easy way to control it,well worth the money.

Suggestion, you might want to go ahead and research/invest in a 5 channel amp while your thinking about buying one. This will run all 4 front speakers and sub. I have MRX-V60(newer version is V70) from Alpine. This will make the speakers you purchased already really sing. The amp is 50x4to the fronts and sub channel is 200x1@ 4ohm 300x1 @2 ohm. I picked up the amp for 207 on amazon.Has crossovers on all channels and subsonic filter for the sub that cant reproduce all the lows. Go ahead and run 4 ga to the amp. this will give you room for future upgrades wihtout running a new power line from your battery. They make a few subs that are powered(amp built into sub enclosure) also. kicker, sound ordinance, focal to name a few if you want to go the easier already packaged route. Hope this helped

 

BE VERY CAREFUL when you mount your amplifier under your driver seat. Its what I did, but the Yaw Sensor is located right near where you will probably want to put one of the four screws to secure your amp. I made the unfortunate mistake of drilling straight through it when securing my amp. I didn't know what I had done until after everything was finished and there was a light on my dash that would not go away. Took me a couple days to go through all the possible problems, but then I finally found a diagram of the truck's interior and noticed that the sensor it right under the seat close to the center console, right where I drilled. It's like a $550 sensor, but luckily I found one on ebay for much less and I installed it and everything worked out ok. Just make sure your check before you drill, don't want to make the same mistake I did.

For choosing your amp, I would make sure that you have an amp dedicate to your subs alone. I don't have any experience using an amp with subs and component speakers, but I think its something you should try to avoid if you can. Class D amps are what most people use for subs because they are more efficient but, compared to Class A & B, they have worse sound quality (which doesn't matter with subs because they are bass, not high frequency). When looking for an amp make sure the RMS of the amp on the ohm value for your subs is equal, give or take a little, to the total RMS of the subs. I like it to be a little more than my subs can handle because I like to know that I am getting the most out of what I paid for. Most amps come with bass knobs so don't worry about it too much, right know I'm looking into a wireless one from Best Buy because I don't like all the wire from it. Best ground from under the drivers seat, like Beach said, is one of the sanded down seat bolts.

Now, I am running two Kicker CVR 10" at 2-ohm 400 watt RMS each with a Hifonix Brutus BRZ1200 Class D amp. At 2-ohm my amp runs 900 watts RMS and my subs can take 800 watts combined RMS, so they are a little over powered. But that's ok because I don't run them on full power all the time, but can if I want.

For choosing your amp it can run you any where from $75 to $350, depending on quality and how much power you are looking for. The Hifonics Brutus I have is really good, but I would stay away from the other types of Hifonics because I have heard they are pretty unreliable. Another thing is don't cheap out on the amp, it really does determine how well the subs preform. Here is a link that helps explain amps and help you choose one:
http://www.crutchfield.com/Learn/reviews/20030722/subwoofer_power.html
Other than that, you can choose which sub you are getting and how many on Sonicelectronics.com and they will give you a list of amps that are in the ball park of what you need:
http://www.sonicelectronix.com/Matching-Subwoofers-Amps

Good luck and let us know how it goes.

 

Never get what you think you are out of an amp unless you calculate total impedance rise.