If a person's happy with their stereo, WTF is the difference? I know a lotta people sneer at kits like the Sony Xplod, but I actually really enjoy mine; there's no subs or amp, but it sounds okay to me. I'm pretty sure it'll sound even better when I put the other two speakers in, as well!

 

Power isn't that important.
If have an old, at its time very expensive, JBL GTi 408 component system with a max power rating of 150W RMS.
The amp has only 4x 40W and it's more than enough to deliver what I need.
Make sure the amp fits to the speakers. A titanium tweeter can sound hard, add an amplifier with the same tendency and it can be very annoying.
You have to to listen to your own preferences.
A good dealer enables you to listen several combinations.

Add a sub to fill the lower stage. There is no need for huge diameters like 12".
But a good sounding sub needs wattage.

Alpine has some good small amps like the pdx 5 with an outstanding value for the size.
It might be a bit more expensive than wally or cheapo amps, but you will enjoy in the long run for many years.

 

I'm gonna hit garage sales or craigslist when I want an amp or subs.

 

You don't need necessarily an amp with an high-in.
It's almost possible to lead out a pre-amplifier line to every factory head unit.

Most head unit use a so called amp circuit (power waffle) This chip has preamplifier inputs, you just need the modell number, the pinout of the amp circuit which can be easily found in most data sheets, and a solder iron to get the cheap job done.

I did it with my Jeep headunit too-as long as I didn't change it.


To give you an example how easy it is I show you how to find the correct connection points.

I Have taken out the integrated circuits in my headunit. They have developed to much heat and sound quality wasn't that good anyways. But they can give a good example.
This is the IC:

The so called TDA 7375. A car amplifier which can be used in 4channel or bridged in 2 channel applications and developing 2 x35W.
In my head unit it was used as a 2 channel application. This is important to know to use the right pins.




now enter the IC code TDA 7375 from the IC onto google search and find this:





On page 4, figure 2, Double bridge, you find the circuit for use as an 2 channel bridged amplifier. This is the layout, we need!
Now we can go on.
We need a left and right channel and a preamp input.
The left channel provides two possibilities- we just need one, either pin 4 or pin 5.
The same goes for the right channel: we can choose pin 11 or 12.

Now we have to find ground for both of our channels.
Pin 8 or pin 9 provide ground as marked with the flat line in the circuit. Every ground marked like that will be fine.

Now you have to buy a simple RCA stereo connector and to solder it to the pins.
Solder the wire shielding of both channels to the ground.

Voila, now you have your factory head unit with a pre out. Done in half an hour with a little knowledge.
You will be a pain in the aftermarket by being able to use your trusted factory headunit.
The funny thing about it is most dealers will tell you it is not possible to get a low output from a factory head unit.
That's simply a lie.
They want to sell you a new unit.

Just as a side hint:
In that data sheet you find the real power output ability of an integrated power amplifier. Don't get fooled by high wattages. It' simply not possible without an additional power circuit. The radio manual of this IC stated a max wattage of 4x 40w. The data sheet shows capability of 25W per channel at 10% distortion. This is completly unacceptable.

But this is common use on all headunits- no matter which brand they are.

Just remember. IC's may vary and individual search can occur!
Feel free to contact me, if difficulties occur.

Enjoy.
Michael

 

the difference between people that say thier stuff is "ok" with them is because they've never heard true 150 watts play through a 4" midrange that made you see spots because it was soo loud and clear... With all due respect, that's an amateur talking... Just to clarify that...

My OPINION(S):
My default thought was, if you are running Infinity speakers, why not Infinity amps??? I had an infinity amp once and it kicked butt... I gotta say my 100 (tested 180) watt MTX amp has lasted about 10 years now pushing two 12" subs bridged... That's gotta mean something too... I'm surely a fan of ANYTHING JL Audio has ever touched... They are high class clearity...

Brands like Sony and Rockford (and others) have multiple levels of quality... They have cheap crap and better crap, but they are "on a budget to sell more quanity" items, so the quality suffers for the $$$ spent... Look for Infinity, Alpine, US Amps, JL Audio, Harmon Karden, MB Quart, and i've never installed a bad Kenwood (but it's been years)... Like previous post, check some other forums and see what experiences people have had with each... I tend to stick to "my" brands and have for years, so use the power of the internet to research... Also, shop with Ebay and Crutchfield for good prices...

If you want clarity, you need a new head unit with pre-amp outputs... Speaker level outputs are at a lower voltage, which means more power demand to make the speakers louder... This creates distortion at a lower overall volume... Which brings up another point, Class D amps are designed to put out higher voltages (watts) with less demand than a standard (non-class D) amp... This translates to higher volume levels with less distortion... My rule of thumb is to use your external amps power instead of the volume **** to create louder music... But NEVER turn your amps up all the way... I usually turn them all the way up, then back off a quarter of the level - that's my STARTING POINT... Tune from there as needed... Also a suggestion for clearity would be "active" crossovers, which will allow fine tuning for your systems freaquencies... Some amps have minimal active x-overs, they should be fine for everyday listening...

Here's a list of things to look for in an amp for your mids/highs:
- RCA inputs (requires head unit with RCA outputs unless you use a converter)
- RMS levels as high or higher than your speakers RMS levels
- Class D is a major plus
- As said before, you will spend good money for great sound
- Take time to tune your system, every vehicle is different

Also, i'd like to know if I could get some of those mids for the same price, that was a good deal...

 

Actually, I HAVE heard the good stuff; I went to school with a bunch of 'tards that put thousands of dollars worth of sound equipment into $500 cars; I can tell a difference, but not enough to matter. I'm not gonna turn it up so loud that I can't hear my truck, anyway.

 

@dmaxtothe...

It sounds a bit strange when I read your lines.
You neither know what kind of amp is used nor what kind of speakers support the midrange.

If you are that "pro" you should know that human listening sensivity is max at the range from 300Hz up to 8kHz( mid to tweeters). Failures in that range go on you nerves real quick.
I do not participate in sound quality discussons. Neither I'm a fan of "stick with the line".

Slew rate or attenuation coefficient of an amp or simplified "control" are much more important to me than pure power.
If you are a fan of: how loud can I go- be happy with it, but accept other opinions,please.
I wouldn't claim myself as a pro- but I've seen some decent units and I know a bit ot two about electronics, and I don't compete with high dollar freaks.

But I travel long distances and want to have as much comfort as I can get.
This is not possible with that wattage monsters you find at best buy or circuit city.

 

Maybe I came off wrong, but if you can play it clear at 150db, then it will surely play clear at 20db was my point... Gives you the option... We all know sometimes alchohol plays a big role in why our system sounds like crap the next day... with a beefy system, you don't have to worry about stuff going bad on you...

I'm no PRO either, just have a few years and a few systems behind me... Sorry if anyone took my "opinions" wrong earlier!

 

Ok, lets have a look where 150db are located at and 20db...

You need ten times more wattage to increase the volume by 3db which equals in doubled volume.

This should help the OP to choose the amp size.
It is absolute useless to compare an amplifier with 4 x50watts with another one being able to deliver 4 x75 watts without knowing the parts used inside.
Electronic parts have an awful side effect. Quality costs money.
You may get easily 1000 watts for 200 bucks- you also may get easily 100 watts for 2000 bucks.
Try to avoid extremes. Neither 1000watts nor 2000bucks are the right way.

 

Look, I was just trying to help the origional post... If ya'll are gonna be smart asses, then I'm done... Dude, buy whatever these two PRO's tell you...