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ok.. here it goes.. if i had an head unit with 52x4 rms... and i'm planning to buy an amp... i have component infinities at the front(605cs) and at the back infinity 652i...now my question is.. if you are buying an amp do you just add the watts that the hu makes to the amp? for ex. my hu gives 52x4 and the amp i'm buying is 50x2(and i buy 2 of those amps-for the front and back) so if your speakers recommended watts is 2-90 watts... is this enough or do i have to buy a 90 watt amp? i'm sorry i'm a newbie at i.c.e. .... i hope someone understands what i'm trying to say.

 
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you don't have to push your speakers to the max ratings....... but the higher the watt the better and louder sound you'll get.....

when u hook up an amp...... the power b/w the HU and amp are not added up...... there won't be power used from the HU..... rather all power straight from the amp...... so in ur case..... it'd be 50watts per channel......

 
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thanks!
but what happens if i hook up the speakers(2-90 watts) to a 100 wat amp?

 
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are your sure the headunit is 52 rms per channel, i think that peak, and no u dont have to buy a 90 watts amp for it

 
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oh yeah.. my bad! i mean 23 rms!

ok.. but if i get a good deal(100 watt amp) can i buy it or will i just f%ck up my components?

 
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Ooooh ... young grasshopper ..... haha .... lol

I will try to help you understand the concepts and not to generalize too much. Here goes ....

Your HU has two types of outputs RCA and High Power.

RCA's are only for hooking up amplifiers. This is a low level signal, like 1/5 of a watt or something. Your amplifier takes this signal and amplifies it to whatever the potential of the amp is ... say 100 watts. You then hook up your speakers to the amp.

High Power is for hooking up speakers directly. This signal will be the 50 watts per channel the HU is rated for. The internal amplifier in the HU powers the speakers.

Now you can use any combination of these outputs to power speakers. Personally I use the front RCAs for my fronts and sub .... and use rear HU power directly for my rears.

My Deck Outputs, 50x4, 3 RCAs (front, rear, sub)
50x2 front:not used
50x2 rear: hooked to rears directly
Front RCA: to amp, then amp to front speakers
Rear RCA: not used
Sub RCA: to amp, then amp to subwoofer

Here is the kicker that will answer your question about what amplifier power you can get.

RCAs come in different powers and are rated in volts. Most cheap decks are 2v. Good ones are 4v or 5v. I have even seen some go as high as 8v. Likewise your amplifier will have a rating on the RCA voltage it can handle. You need to mentally compute to match them. You do this with the gain ****.

Example of the where your amp will output max power of 100 watts:
HU is 4v output. Amp is 2v. Here your HU can overdrive the amp. In this situation you should never have the gain past about 50%.
HU is 5v output. Amp is 4v. Here your HU can overdrive the amp. In this situation you should never have the gain past about 80%.
HU is 4v output. Amp is 4v. Here your HU and the amp match. In this situation you can have the gain up full.

This is also the same **** that will determine the max wattage the amp will output when driven. It is bad to overdrive the amplifier because you can cause the amp to try to output more power than it is rated for. So in the first two examples above if you turned up the gains even more you could fry the amp.

You can further tweak the gain lower to set the approximate wattage to the speaker if needed. So if your speakers are 80 watts and you get a 100 watt amp ...... you need to back off 20 watts or so.

Here are some examples:
HU is 4v output. Amp is 2v. Amp maxes out w/ gain at 50%. Back gains off to about 40%.
HU is 5v output. Amp is 4v. Amp maxes out w/ gain at 80%. Back gains off to about 65%-70%.
HU is 4v output. Amp is 4v. Amp maxes out w/ gain at 100% Back gains off to 80%.

By now you have the knowledge on how to get the most power to your speakers from an amp following all the wattage and voltage parameters you need to take into account. The last step is to maybe turn down the gains a bit more to balance the system out.

Example in my car:
Sub amp: 800 watts
Subwoofer: 1,500 watts
Gain can easily be at 100%

Front amp: 70 watts
Fronts: 170 watts
Gain can easily be at 100%

In reality I can have both my gains at 100% .... the problem is that the fronts are screaming before the sub even wakes up. So I backed my gain off for the fronts to about 65%. Now when I turn up the volume the fronts and the sub balance out.

In a perfect work you want to set all this and have the system balance out right when the volume **** on the HU is at about 80% of max volume.

My HU goes to 62 ..... so realistically the signal starts to get strained at about 54 or so. So this is the number I tweaked it all to max out at ....

Getting the idea yet ?????

 
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and that 23 rms is some dirty power, so after distortion, and after considering it all, youll probably never get more than 14 per channel out of that headunit

 
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thanks! ok.. so what amp do you guys recommend? i have infinity 605cs components and for the rear infinity 652i. i just want to power up my front speakers(maybe later the rears). i plan to put a small sub later... i need my trunk space. so my headunit has 2.0 preamp volts. what do you guys recommend?

 
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I have a Kicker 150.2, thats about 35x2 @ 4 ohms ..... more than I need on my Diamond Components.

Anything reputable brand amplifier in the 35 to 120 watt range would work well ....

Common Reliable Brands
Orion
Earthquake
Pioneer
Diamond
Eclipse
Kicker
Hifonics
Kenwood
MMats
Rockford
Xtant
Zapco
Sounstream
JL Audio
Alpine
MTX
JBL

 
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You say you're going to be getting a small sub later, you could get a 4 channel amp and have two channels powering the front and then the other two channels bridged to the sub.

 
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thanks joe, nice info. what i dont understand is how to match up rms/peak of subs to output of amp. and the ohms thing confuses me too. any webpages would be helpful if you dont want to explain it. like ferio, i am a newbie as well

 
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RMS is the average ..... Peak is the main number you wanna focus on ..... but its still just a number.

If you have a 400 watt speaker and a 450 watt amp you will be fine. Overall its about keeping that gain **** under control.

Ohms is resistance. The lower the resistance the easier it is to push the speaker.

If you have a 4 ohm sub and a 2 ohm sub ...... the 2 ohm sub is theoretically twice as easy to drive as the 4 ohm. When speakers are easier to drive amps tend to use more current .... therefor output more power to that speaker.

Now amplifiers are all rated differently. Most typical amps will put out more power into a 2 ohm load than into a 4 ohm load. Others can't handle 2 ohms loads at all. Others are stable to even 1 or 1/2 ohm ... wow. The lower the resistance, the more current the amp will try to output. You will never see an amp stable at 0 ohms because that is basically a dead short.

This is how amps can get fried ..... hook up speakers w/ too low a resistance, the amp uses more current than it should, outputs more power than it should, amp gets way way too hot and BOOM .... one toasted amplifier w/ smoke rolling out. Amps are dumb and just try to drive what speakers you hook up to them.

A speaker can't change its resistance .... it just is what it is. But the wiring is what determines the resistance the amp see's. Parallel wiring cuts the overall resistance, series adds all the resistances. JL audio has a good website laying this out.

Using a amp with these rating ...
100x1 @ 4 ohms
150x1 @ 2 ohms
200x1 @ 1 ohms

Some examples:
one 4 ohm sub, amp puts out 100 watts to that sub
two 4 ohm subs in parallel, the amp sees 2 ohms and puts out 150 watts, 75 watts to each sub
two 4 ohm subs in series, amp sees 8 ohms and puts out 50 watts, 25 to each
four 4 ohm subs in parallel, the amp sees 1 ohm and puts out 200 watts, 50 to each sub
four 4 ohm subs in combo of series and parallel, amp sees 4 ohms, 100 watts, 25 to each

one 2 ohm sub, sub gets 150 watts
two 2 ohm subs in parallel, amp sees 1 ohm and puts out 200 watts, 100 to each sub
four 2 ohm subs in parallel, amp sees 1/2 ohm and puts out 300 + watts, amp go BOOM
four 2 ohm subs in series, amp sees 8 ohms and puts out 50 watts, each gets about 12
four 2 ohm subs in combo of series and parallel, amp sees 2 ohms and puts out 150 watts, 35 to each sub

one 1 ohm sub, sub gets 200 watts
two 1 ohm subs in parallel, amp sees 1/2 ohm and puts out 300+ watts, amp go BOOM
two 1 ohm subs in series, amp sees 2 ohms and puts out 150 watts, each gets 75 watts
four 1 ohm subs in parallel, amp sees 1/4 ohms and puts out 400+ watts, amp go BOOM
four 1 ohm subs in series, amp sees 4 ohms and puts out 100 watts, each gets 25 watts
four 1 ohm subs in a combo of series and parallel, amp sees 1 ohm and puts out 200 watts, 50 to each sub

So you need to pay attention and get what works best for your configuration and what the amp can handle.

If you had this amp ...
100x1 @ 4 ohms
200x1 @ 2 ohms

You would want to get something that give the most power into 2 ohms ......
1) one 2 ohm sub (direct 200 watts)
2) two 4 ohm subs (parallel, 100 watts each)
3) two 1 ohm subs (series, 100 watts each)

Not power into 4 ohms ....
1) one 4 ohm sub (direct 100 watts)
2) two 2 ohm subs (series, 50 to each)

Get the idea ?????

 
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YES! Thank you. now shopping around will be much easier. very nice thread