my first amp, i am a dummy. vehicle is 2001 Dodge Ram 1500 pickup, 2 door regular cab, w/o chrysler infinity system. i have aleady replaced the factory unit w/ a pioneer DEH-2800MP, which is 26w rms, 40 peak.

the truck has provisions for 4 speakers, (2) 6x9 in doors, and (2) 5 1/4 in rear cab area. its a regular cab, and a small area. there are no speakers in the rear, and i had planned to leave it that way, and just install an amp and a pair of 6x9's, no subwoofer.

planning on a 2 channel amp. i will use amp installation kit for power wire, fuse, rca's, and probably will run new speaker wires.

my goal is to get good clean sound at normal volume levels. i'm 50 years old and a little hard of hearing, but i don't intend to rattle windows or impress the neighbors.

now my questions.

1. how do i match amp and speakers. and how, if at all, do i consider the head unit (26w rms). is this the right combination ?
for speakers rated at 40w rms, such as pioneer, would i need to use a small amp, such as 50w rms x 2 @ 4ohm.

for speakers rated for higher 75w rms, such as rockford p1694c, could/should i use a bigger amp like 60-75w rms x 2 ?

is there any downside to over-amp'ing ? such as, if i found a bigger amp cheap, like a 100w rms x 2 @ 4ohm, and used it with lower wattage speakers 40-75, and kept the volume level and/or gain turned down to normal listening levels, would it work out ok ?

2. are there any other problems with over-amping, such as excess heat, or faster battery drain ?

3. if you turn down the gain, does it reduce heat and reduce battery drain, or does it remain the same ?

4. what should i expect in terms of battery drain ?

educate me please. thanks, doug

 

First off, the DEH-2800MP is only 22W RMS. But that won't even matter because you amping the only 2 speakers your gonna have with an external amplifier, correct? Because of that, you're not using the headunits internal amplifier, so the 22W RMS means nothing. What you want to look for when using an external amplifier is the headuits pre-out voltage rating, which in the 2800mp's case is 2.2V, which isn't great, but it isn't terrible either, it's a very average output voltage, so you should be all set.

Now for matching speakers to an amplifier. In general, you can run ANY amp on ANY speakers. It's all in how you set them up. You could run a 1000W amp on your 65W 6X9's. The amp will work less, and therfore produce a cleaner output to the speakers, but there is a point where the additional power is wrthless, 1000W would be extreme overkill. When running an amp that is too small, as long as you set the gains right, and the amplifier is not clipping, the output can still be very clean, but you won't get as much output as you may like. The speakers can handle more than the amplifier can cleanly supply. The problem with underpowering, is people try to get the most out of the amplifier to get their desired output from the speakers, and end up turning the gain too high, getting a clipped output, and damaging the speakers. Surprisingly, people tend to kill speakers more from an amp that's too small, than from an amp that's too big. In both cases, even with the smaller amp, "overpowering" is what kills the speakers. But that's a little more complicated to explain and meaningless to your situation.

So in short, pick an amplifier with an RMS rating very close, or even a little more, (to than the RMS rating of the speakers your trying to drive. At the same impedence rating (4ohm) If you find a larger amp for cheap, by all means get it. It will only benefit you. Just make sure the ratings are in RMS, preferably "Continuous" RMS, not peak.

 

Oh yeah, and with an amplifier that size, battery draw won't be much of an issue, especially with the vehicle running.

 

[blockquote]First off, the DEH-2800MP is only 22W RMS. But that won't even matter because you amping the only 2 speakers your gonna have with an external amplifier, correct?First off, the DEH-2800MP is only 22W RMS. But that won't even matter because you amping the only 2 speakers your gonna have with an external amplifier, correct?
[/blockquote]
you are correct, 22w rms, not 26, my mistake.
yes i will operate only 2 speakers, both amp'ed, and none directly from the head unit.
( i did not understand that that the rca's were low-level, and unpowered from the head, and therefore irrelevent to the discussion. i told you i was dummy. thanks for that.)

ok, so i understand that its bad to underpower the speakers, but that its ok to overpower the speakers within reason, but it becomes a waste of money.

now what about the battery when the truck is sitting there not running, with the amp on and playing. what should i expect, and does a larger amp (75-100w rms x 2 @ 4ohm) suck the battery down faster than a 50-60w ? and how long are we talking about assuming a good battery. 1 hr ? 2 hr? 4hr ?

 

A 100x2 amp should be able to play at moderate-medium volume for 1-2 hours given a decent battery. It depends on the battery really, there can be a huge difference between cranking amps and that is what you want to look at. CA is measured at a given voltage for the amount of one hour if i'm not mistaken, the higher the number the better.

 

ca is how many amps the battery puts out at 32 degrees F....cca is at 0 degrees...nothing to do with voltage....if you want to play your stereo for a long time get an optima yellow top...i ran 4 12 inch subs each at 1000 watts, powered by a 5000 watt amplifier for around 2.5 to 3 hours....with a small amp like the one you plan on buying...you can probably last around 2 or so hours with a stock battery...but mind you it all depends on how old the battery is...also..your stereo will be slightly louder while the vehicle is running becuase it's getting 14.4 volts instead of 12.6 volts

 

Since most batteries dont list the reserve capacity minutes (RCM), CA is the next best alternative to look at when comparing batteries. And voltage does matter immensely, that is one central part to his question. If the voltage dips to low, his truck will not start.

Back on point, you should be fine if your battery you have now is decent.