Amplifying 6X9's

[Black Box]

OK guys, I need some advice. I have the following setup in the GN:
Kenwood CD Receiver KDC 217 rated at 45wx4
Door Speakers: Kenwood KFC 1368 2-ways, 2-28w RMS, 110w max, rated at 4 ohms
Rear Speakers: Kenwood KFC-6908 4-ways, 2-55w RMS, 220w max, rated at 4 ohms

I also have a set of Infinity Reference 3052cf's that were in the dash, but I had to take 'em out because 6 speakers were drawing too much power out of a 4x receiver. It was screwing up the bass after extended periods of time (this is what Crutchfield told me).

Now I want to add an amp to the rear 6x9's. How much power can I put to them? I would probably use the speaker level inputs of the amp and run the speakers off those, unless someone sugggests otherwise.

I just don't have the scratch for an amp and subwoofer right now....I will add one later. But for now I need something to boost the power of the system I have. Would 100-150w be too much power for the 6x9's? Crutchfield told me to not go over 20% of the recommended RMS rating of the speakers. Granted, I don't know too much about car audio, but that sounds kinda low to me
I was looking at the Kenwood Excelon and Kicker Impulse series amps.

TIA
Steve

 

[cturboaddict]

IS the amp a 150 watt amp or is it RMS 150 watt.

If it is RMS that is too much, if the 150 wattage is max then you would be okay. Or you could run a 100 watt max amp in 2 ohms, just make sure it is stable for that.
Personally i like the Rocksford Fosgate amps. But it is all about preference really, Unless your into competion. But back to the subject, make sure the amp has a built in crossover and also, if you want to really find out the best answer to your question, call up a reputable car stereo place and just act like you want to buy an amp from them and ask. Crutchfield has never done me wrong, they normally know what they are doing. And when you go to buy a sub, go for the JL audios- they rock so nicely. I had two 10inch w6 running off a 200 w Rocksford Fosgate and man did they rock and they sounded great with any kind of music.

 

[Black Box]

I was thinking about 100w-150w max power.
How do I wire it for 2 ohms?
Here is one of the amps I was considering:
http://www.kenwoodusa.com/product/product.jsp?productTypeId=11&productLineId=1&productId=448
Kenwood KAC-X201T

Thanks
Steve

 

[salvageV6]

The amp. link you posted is only a true 50 watt RMS amplifier.

It will work fine with your rear speakers. They are rated for that power.

Buy it. Kenwood amplifiers are nicely made.

I have been using them for 23 years now.

I personally would go for a larger amplifier using the buy once theory and it will be more in line with an upgraded system in the future.

Just my .02.

 

[Black Box]

Salvage,
I'm all for more power!
There is another one, the KAC-X301T that is rated at 100W RMS. would that be too much? It's 200Wx2 max.
Thanks
Steve

 

[mcss383]

Originally posted by salvageV6
Buy it. Kenwood amplifiers are nicely made.

I have been using them for 23 years now.

I personally would go for a larger amplifier using the buy once theory and it will be more in line with an upgraded system in the future.

Just my .02.

Ughhh, I hate kenwood....of course I had an amp of theirs that broke, sent into warrenty repair (it was there for 6 months) and then put it back in. Several months later it broke again.....

I DEFINATLY AGREE with the buy as much as you can upfront theory. I have WASTED so much money buying 'just enough' at a time to then later on upgrade. Get all you can now, it will be worth it.

 

[cturboaddict]

Just like i said.

Everyone has their own opinions. But good point made, spend the extra and get the bigger amp, you can run it harder but it wont smoke the amp.

 

[Black Box]

Cool....thanks for all the help. Time to go buy one today!
Think I'll get the X301T. That should be plenty without worrying about frying anything.

Steve

 

[salvageV6]

Steve the key to saving all the speakers and not having too much distortion is gain matching.

What you do is find the point on your volume control that the head unit power starts to distort the FRONT speakers, I would fade them full front for this test. Hopefully the power level doesn't change when you do this, I don't think it does it should simply kill the rear speakers which we want to do.

Now after the amplifier is installed try setting the gain control on the rear amplifier to max. out the rear speakers with the start of distortion at the same volume on the head unit that made the fronts just start to distort.

When it starts to sound bad both the front and rear speakers will be distorting together and neither will be severely overdriven at this point.

Chances are with this setting the rears will be way louder than the fronts with the new amplifier on them. That is a good thing. Now you can simply lower the gain control on the rear speakers some more and balance the sound that way to your liking. Now you will never overdrive the rear speakers with the new powerful amplifier. If you upgrade the rears you simply rebalance the system.

PS: I can help ya balance it when I get my coilpack back.

 

[salvageV6]

Steve, I just checked the spec's. on the 301. I didn't see where it accepts speaker level inputs????

Are you going to use a speaker to line level converter to run it?

Better double check how you will hook up the input to the amplifier. If you have line outs on the head unit I would use them.

 

[Black Box]

salvage, I did notice that about the 301, I will just have to use the line out jacks instead.

Ah, the infamous dyno-day-saving coil pack! Hey, wait a minute....maybe I can wire that into the system for a little more punch? (j/k) OK maybe not!

When is the next Wal-Mart cruise? This weekend or next weekend?
Steve

 

[cturboaddict]

What is this walmart cruise???????? Is this a inside joke or are you guys for real???

 

[salvageV6]

It's for real. Next weekend in Wallingford. Don't worry about the coil pack Steve I found another used spare when I went to the track rental.

But if you do put the thing on your stereo we can set the gains with Casper's tester.

Gotta love a stereo that is good to 5.5K.

Walmart cruise is sponsored by a Ford club open to all year performance and custom cars from what I have seen.

Starts at 5:30pm and fills up quickly usually.

 

[Black Box]

Salvage, yeah that CP tester comes in handy!

OK, I spent some money....didn't end up with either of the the Kenwoods (I guess those are old models of something). I got an MTX 4122 at Circuit City for $139.99, plus Monster Cable patch cords and amp installation kit. Here it is:
http://www.mtxaudio.com/caraudio/products/amplifiers/thunder4122.cfm

Not quite as powerful as you recommended, so I may take it out and exchange it for the 4202: http://www.mtxaudio.com/caraudio/products/amplifiers/thunder4202.cfm.
The salesman at claimed that the 4122 was about all the 6x9's could stand.

It sounds soooooo much better than it did without it. The bass is much more powerful, and it is substantially louder.

Thanks to all for your help.

Steve

 

[mcss383]

Originally posted by Black Box
The salesman at claimed that the 4122 was about all the 6x9's could stand.

That doesn't suprise me one bit. Odd as it is, most people that work at car stereo shops don't have a clue about how the gain works or why its there. Sadly most of them consider it a volume control....

 

[Black Box]

mcss383,
I can turn the gain up pretty high on the 4122 amp. Not knowing much about car stereo (I know just enough to be a danger to myself ), could you please explain what exactly the gain control does? Is it just regulating the amount of wattage going to the speakers, or is there more to it than that?

Steve

 

[zam70]

The gain contol is an INPUT level control. It is there to match the output level of the head unit to the input of the amp.

stereo tips

#1 buy as much power as you can afford
#2 cross speakers off correctly
#3 set gains correctly
#4 have all wiring up to snuff+
#5 be smart about the volume. If it is distorting TURN IT DOWN!


Follow these basic rules and you will NEVER blow a speaker. I have run as much as 1000 watts into a 100 watt speaker for years and it lived a happy life

The #1 reason a speaker blows is from user error.

 

[salvageV6]

I'd go with the 4202 it will work fine at 2 ohms or 4 ohms and nicely power your front speaker soundstage when you upgrade the system with subs., kickpanels or upgraded front speakers.

They prolly recommended it because it was an easy install with the high level inputs and auto sensing turn on feature.

Go one model up and it should be very useful in the future.

Just my .02.

 

[Black Box]

Speaking of upgrades....
Well I decided that not matter what amp I put with the 6x9's, I wasn't gonna get the bass I wanted. So I went off the deep end and bought another amp and 2 subs:
MTX 8302 amp:
http://www.mtxaudio.com/caraudio/products/amplifiers/thunder8302.cfm
Infinity 1020 10" subs:
http://www.infinitysystems.com/caraudio/product.asp?ProdId='1020W'&Ser=REF&Cat=SUB
And Q-logic box:
http://www.crutchfield.com/cgi-bin/S-rccNrfmZ5gq/ProdView.asp?s=0&c=10&g=842&I=044H6510DX&o=m&a=0

salvage, I am definitely gonna need your help! I got it all installed and turned it on, but being a newbie at car stereo, I need some help balancing the system. I ran Monster Cable patch cords from the output of the 4122 amp to the inputs or the 8302. I didn't 'bridge' anything on the outputs, just hooked up each sub to each output on the amp. Would there be any benefit to bridging? I turned the power on and noticed that bass wasn't very 'punchy' and crisp. More boomy than anything, that was kind of dissapointing. I get the distinct feeling that I'm not doing something right and don't have it adjusted correctly, so I shut it down before I popped something in the amp or the subs.
So salvage, when you have some time, maybe we can meet up and you can tell me WTF I did wrong.
Thanks
Steve

 

[Black Box]

Well I did some fine tuning to the system tonight. I switched it to a 2 ohm load and that made quite a difference....until the battery died.
I didn't get to play too much before that.

Steve