unpocoloco

I think I've finally pieced together what I want to get. Thanks to all who have been following my threads and helping me out along the way. I know that whatever I get, it likely won't change for many, many years (heck just finding the time to look took me over a year!), so that's why it's really important that I get this right the first time. Given budget constraints of course (and size constraints...I refuse to sacrifice trunk space, as I need what I've got. Them's the brakes!). Definitely made the choosing harder, but I think in the end it'll be worth it.

So, I've decided I like the JBL GTO637 6.5" 3-way speakers ($120 from most places, $87 at woofersetc?? WTF?!). These would replace my front 6x8's. I shudder to think how much the install is going to cost on these guys, though. I don't know how much work will be needed to fit these 6.5" speaks into the former 6x8 spot. Any guesses?

unpocoloco

Next, the rears. I eliminated the Kappa series after a couple of listens. They are great speakers, don't get me wrong! However, I think by themselves they do not have enough bass. Pair them up with a sub of any sort and they'd be the speakers to go with. Since I'm not getting a sub...

It then was a battle between the JBL GTO937 6x9" 3-ways ($150) or the Focal 690CA1 2-ways ($199). Again, both are very nice speakers. So I don't think I can really go wrong either way. After going back to the store one last time for a comparison listen, I felt that the JBL's sounded better on some songs, and the Focal sounded better on others. Generally I liked the JBL's a tad more however.

Since it is so close, I'm giving the tie to the JBL's for a few reasons. One, some say it's better to stick with the same brand of speakers. I don't give this a whole lot of weight...I'm going to go with whatever sounds better, personally. But more importantly, two - they have the same impedance as the fronts I want (2 ohms). If I don't have to worry about mismatching impedances and fiddling with gains to compensate (a lot!), so much the better. And finally, three, they are $50 cheaper. More like $90 if I use woofersetc. What is the DEAL with that place? Is that for real?

unpocoloco

Finally, the amp. How much power do I need here? I am a little confused.
JBL GTO637's: 60W RMS
JBL GTO937's: 100W RMS

Therefore, if I got a 4 channel amp that put out 90Wx4 (at 2 ohms) that should be plenty, right?

Could someone explain how the amp is putting out MORE power at a lower impedance? (It provides 60Wx4 at 4 ohms) Since power is directly related to resistance, I'd expect half the ohmage to yield half the power. I'd expect the amount of current an amp can put out to be constant. I guess this is where I must be mistaken, but this is strange to me.

lurch519

think of resistance like weight in your car. the more weight you have in the car, the slower it is.

WikkedOne

you have it right unp. power IS directly related to resistance... but the resistance is in the speaker not the amp. So if you can push 60 watts through a 4 ohm speaker. it is obviously going to be easier to push more power if the speaker isn't resisting as much. and of course if you were to run 8 ohm speakers you would get more resistance and therefor less power.



good luck on the install let us know how it goes

jstkilntim

You are looking at it the wrong way. An amplifier is designed to safely supply its highest rated power at its lowest recommended resistance (say 2 ohms). That is the amp you are buying. You aren't buying an amp rated at a low power that can double it's power at a lower resistance.

An amplifier's output is limited to it's input (say 14 volts). Most amplifiers are designed to put out a specific voltage at a specific voltage input and speaker impedence to get their power rating. If you double your resistance and output voltage stays the same, amperage (and power) go down.

For the "techinically advanced" people out there, I know there are amps that do change their output voltage, and the engineering of amps is way more involved than I make it seem, but I was trying to keep this simple and understandable to most.

unpocoloco

I guess I'm still hung up on P = IV = I^2*R.

As Wikkid said though, I might be confusing resistance of the speaker w/that of the amp. So if I look at it THIS way...decrease the impedance of the system, keep the voltage constant...I goes up...bingo, more power. I can buy that!

So, if I have an amp that puts out 90Wx4 is that going to be okay with a speaker rated at 60W RMS?

jstkilntim

As long as it is a quality speaker and a quality amp, you will be fine. Adjust the gain so that there no distortion at your maximum listening level and you will have sweet music at normal listening levels.