I plan on upgrading my stereo and Head Unit next month. I'm planning on purchasing the Kenwood DNX-7100 LCD GPS head unit and all of the goodies. I have a torn speaker on my front driver side so I plan on replacing the front pair (if not all) at the same time.

Here is my deal though. My F-150 came with what Ford calls the "audiophile" system. This included a subwoofer and built in amp to power it seperately. The sub is only an 8", and while that is tiny to most stereo fanatics, it provides just enough bass and hit for my tastes. So I do not plan on upgrading my sub. I also do not really want to amp my speakers...I know I should to get the best out of my system but at this present time its just not necessary.

I am leaning towards adding the Polk db571 5x7's (stocks are 5x7 and i want this to be easy). I guess my question is,

1. is the DNX7100 well equipped to power these speakers.
2. is there any decrease in quality with replacing all 4 speakers instead of just the front? (not talking rear fill, talking watts etc.)

here is some info on the head unit and speakers.

DNX7100 -
RMS Power Output - 22 Watts
Peak Output - 50 Watts
RMS power bandwitch - 20-20KHz
Preamp Voltage - 2.0 Volts
Preamp Outputs - 3 pairs

Polk DB571 speakers -
Sensitivity - 93 dB
Frequency Response - 52 - 22k Hz
RMS Power Range (Watts) - 6-60
Peak Power Handling (Watts) - 180
Impedance (Ohms) - 4




fyi - i'm a complete newb when it comes to car audio so if i left anything out or added useless info i'm sorry. Thanks for the help.

1/31/2008 12:13:27 PM

Fist, I highly recommend you get a small 4channel amp for the speakers. Something $100 and 4x35W RMS will sound a lot better than the HU powering them.

1. The Kenwood amp will power them ok, as it will only put out 18W RMS, and the speakers would be happiest at 60-100W.

2. There will be an increase in sound quality by going from factory to aftermarket.

1/31/2008 1:10:03 PM

You might want to find out if your stock stereo is already amped. one of my friends hooked his up and to his surprise he was putting an amped signal into an amp... and -68db was so loud it it hurt.

If its not amped.... you really might want to amp it... My Polk speakers are all messed up from my Kenwood head unit because (keep in mind i have a lifted jeep with loud tires and suspension) my unit would be clipping if i turned it up loud enough to enjoy the music at highway speeds...

Sure they weren't over powered but sending them a square wave signal (where the tops and bottoms of the wave are cut off due to lacking power) is just as bad for them imho.

But i'm willing to bet if your sub is amped there may be a small amp on the rest of the system too.

1/31/2008 1:58:07 PM

^yeah, that is what kind of happened to my eclipse speakers in my Jeep too.


I dont think the rest of the system in my F150 is amped. I believe it's just the sub.

1/31/2008 2:03:24 PM

I'm planning on amping mine soon with a jl 75/4

1/31/2008 3:20:18 PM

i just don't feel like amping cause i dont want to reroute my wires

1/31/2008 4:19:42 PM

ohh i know i'm dreading it too.. taking all that plastic off and running wires that actually have some gauge to them.

1/31/2008 4:26:02 PM

You only need to run an 8 guage wire kit for a modest 4 channel amp. Running speaker wire isn't that difficult, and you can grab the wire inside the cab and use the factory wires into the doors.

1/31/2008 4:31:50 PM

yeah, the more i sit and read about it the more and more i just say fuck it and think about going all the way.

hopefully my guy will give me a good price on the head unit and those accessories.

1/31/2008 5:02:09 PM

what are some trustworthy amp brands on the lower price end? I'm not looking for a Rockford Fosgate by anymeans, but I also don't want a flea market brand either.

This one looks good and i'm getting the Kenwood HU too http://www.sonicelectronix.com/item_5907_Kenwood+KAC-6402.html

2/1/2008 9:32:25 AM

I had a older kenwood KAC amp and loved it. Definately underrated, or at least the older ones were.

These are also a good amp for a cheap price:
http://www.sonicelectronix.com/item_8856_Power+Acoustik+PS4-1600.html
http://www.sonicelectronix.com/item_9176_Clif+Designs+CD4.4LE.html
http://www.sonicelectronix.com/item_8563_Kenwood+KAC-8403.html
This is a beast of an amp:
http://www.sonicelectronix.com/item_4249_Memphis+16-MCA2004.html


You may consider a 5 channel amp, and get a little more oomph out of your sub, at the same time as upgrading your speakers. Something like: (keeping from the same website)
http://www.sonicelectronix.com/item_10145_Infinity+Reference+5350a.html

2/1/2008 9:53:01 AM

what are the cons of running speakers that have a continuous RMS of 60W through an amp rated RMS 80W continuous?

2/1/2008 10:12:30 AM

I doubt you'll ever turn it up to 80w RMS you typically want your amp to go a little higher than the speakers so you can turn the speakers up to their max w/o clipping.

Basically if you're not stupid with it a bigger amp is better but if you want to see if your ears will bleed @ max volume the bigger amp does have the ability to fry the speakers.

2/1/2008 10:31:46 AM

None.
An amps power is not always max. The volume turned all the way down is 0W, and as you turn the volume up it goes up to the RMS, and then some. It is a Logorithic increase.
You can turn the amp level down, to where you are not going to damage your speakers as well.

It is always better to overpower your speakers than to underpower them. This is because when turned up, you are still sending a clean signal and are not near the extent of the amps power.
Also with good clean power, speakers can handle much more than their rated power.

Another difference, is that amps are rated with electical energy consumption, and speakers are rated by thermal handling, which are a little bit different.

If you run an amp too hard, you get a clipped signal, which is a square wave, and you are very likely to kill your amp or your speakers.

2/1/2008 10:33:40 AM

Cool, thanks for all of the info. I've never been big into car audio but am getting excited about putting a new system into the truck.

I'm sure i'll have some more questions very soon.

2/1/2008 10:46:57 AM

http://www.crutchfield.com/cgi-bin/ProdComp.asp?g=51900&s=0&c=3&cc=01&compareItems=500SPS57C2&compareItems=107DB571


comparing these two speakers, which would yall recommend?

2/2/2008 4:59:58 PM

Alpine
Greater frequency range
Greater overall power handling
Deeper mounting depth Usually leads to better linear response, though that is a very broad generalization.

Polk
Higher efficiency (93dB compared to 92dB, almost negligable)
Greater RMS power handling, though that won't matter with a good signal.

I would go with the Alpine, and have had great experiences with their R and S lines.

2/2/2008 5:58:32 PM

thanks man, i appreciate all your help. Here is my thinking though...


They are the same price, but crutchfield has the Polks as buy one get the second pair half off. saving 50 bucks... I could take that 50 and get a pair of the polk db1000 tweeters.

what do you think?

2/2/2008 6:14:21 PM

From my experience with Polk... they're good speakers but they take a good long while to mellow out (not sure what the technical term for that is...moparnum5 knows far more about this stuff than I do). The tweeters continue to be too high for my taste, but after a few months/years of use the whole system sounds a lot better as a package.
I'm pretty sure the speakers Danny has in his Jeep are the Infinity Reference series. Best speakers I've experienced yet-- although I don't have any personal experience with Alpine other than short tests, so I can't say much for the sake of comparison.

And I'm pretty sure Danny chose the Polks because they were on sale--
Looks like they don't have the exact ones on the site anymore, but they're definitely DB series.


[Edited on February 2, 2008 at 6:33 PM. Reason : more]

2/2/2008 6:25:31 PM

If you get the tweeters, you are going to need to get crossovers, or bass blockers. Otherwise, you will be sending full signal to speakers made to play over 2k hertz.
It will raise the sound stage, but if you are going that route, you need to get crossovers.

2/2/2008 7:14:04 PM

the site says that 2 in-line crossovers are included with the tweeters. Is that all i would need?

Quote :

"High-Pass Crossovers: Each in-line crossover features a 12dB/octave, 4kHz high-pass network for the tweeter. The attached input wires are 45" long and are tinned on the end. The attached output wires are 24" long and have female quick-slides on the end that plug into the wire attached to the tweeters. Electronic Tweeter Protection Circuits: Each crossover has a built-in protection circuit that guards the tweeter against accidental damage from high power. "

[Edited on February 2, 2008 at 9:15 PM. Reason : add]

2/2/2008 9:12:21 PM

bump

2/4/2008 7:53:26 AM

Yeah, that would be one way. That is a little high in the HZ range but still ok.

2/4/2008 7:57:26 AM

Yeah i was thinking about swapping all of my speakers out to jl component setups but i really don't know if i want to put that kind of money into the jeep, i mean its always going to have tire hum an suspension squeaks in the background

2/4/2008 8:20:07 AM

Not worth it IMO. Just get some cheaper components, or marine coax speakers.

2/4/2008 9:03:19 AM

^^^MaximaDrvr, explain that to me just a little bit, haha.

I was hoping it would be ok, b/c my current stock setup has 5x7's and a stock tweeter located above it. There isn't an external crossover, so i was hoping to just be able to replace both w/o one. Didn't really want componets and figured these tweeters would just give me some added clarity.

2/4/2008 9:17:27 AM

With an external crossover, most systems are set so the tweeters play above 2.5kHz. This picks up a lot more instruments, vocals, and other relatively high pitches.
The in-line high pass filters provided with those tweeters have crossover points at 4kHz. This is mostly just cymbals and other very high pitched sounds.

The high pass filters will work just fine, you are just going to be getting a full signal to your woofer in this setup as well.

Overall it isn't bad, but you would be better off with components over a coaxial speaker, and a additional tweeter. Your coaxial speaker already has a tweeter, so you may end up with a very bright if not harsh upper sound.

2/4/2008 9:37:13 AM

good point. i'll hold off on them for now i think

2/4/2008 10:17:31 AM

ok, another "If" scenario...

1. is there any sound field issues with running round speakers in the front and ovals in the rear?

If not, would getting these Polk components http://www.crutchfield.com/App/Product/Item/Main.aspx?o=v&g=399&i=107DB5251&search=polk+db&tp=12
be worth it?

and if i did that, would a 4x60 - 4x80 4 channel amp still be enough to power the system?

2/4/2008 2:11:32 PM

That is a much better option than running 5x7 all the way around.
Round speakers sound much better than oval, and distort less as well.
Manufacturers use ovals because they produce more bass (more surface area moving).

A 4x60-80W amp will still work just fine.

2/4/2008 2:13:54 PM

but having the components in the front and ovals in the rear shouldn't have any problems?



I think that's what i'll do, components in the front, 5x7's in the rear, and my small stock 8" sub to provide what bass i like.

[Edited on February 4, 2008 at 2:24 PM. Reason : add]

2/4/2008 2:15:27 PM

Nope, no problems there.

A lot of sedans run 5 1/2 or 6 1/2 round up front and 6x9 in the rear decks.

2/4/2008 2:56:30 PM

speakers are ordered.

i need some more advice on an amp. You have any experience with Power Acoustik?

I know the amp is one of the most important pieces, but i really dont want to spend 300+ right now.

Maybe I can check the pawn shops out this weekend, craigslist didn't have anything

2/4/2008 8:30:51 PM

Quote :

"It is always better to overpower your speakers than to underpower them."

Bullshit. Too little power will only cause the maximum output level to be low. Abuse and the idiot controlling the volume knob blow speakers with low powered amplifiers. If driving a speaker with low power would cause them to fail, speakers would fail every time you lower the volume on the head unit.

Plus, adding a 30x4 amp isn't going to produce a difference compared to the 22x4 internal amp the radio comes with since you have to double your power to gain a 3db difference. The stock radio will power those speakers fine unless you really want to crank it then I'd recommend at least a 75x4 amp.

2/4/2008 9:12:08 PM

^word, i got ya.

but i ordered these http://www.crutchfield.com/App/Product/Item/Main.aspx?o=v&g=399&i=107DB5251&search=polk+db&tp=12

for the front, so an amp is necessary now i believe

2/5/2008 6:53:04 AM

^it all depends on how loud you want to listen to your music. those speakers are fucking awesome. i put a set of the 6.5 db polks in my wife's car. i originally had a 100x4 amp powering all her speakers but i had to fix the amp and never put it back in because she just doesn't listen to her music that loud. i put an alpine in it with the same power rating as the radio you're getting and trust me it gets plenty loud and they sound great. before you spend the money that you didn't want to spend in the first place on an amp i'd put the radio and speakers in first to see how you like the volume. if you turn it up to the point they start distorting and it's still not loud enough then consider an amp. the speaker will not sound any different with an outboard amp, it'll just play louder.

[Edited on February 5, 2008 at 9:27 AM. Reason : -]

2/5/2008 9:27:15 AM

When it comes down to it, its always the idiot controlling the knob that blows up speakers.
But if you just use the stereo while you're driving the car and not trying to throw a block party using it.

An OVER POWERED amp will make sure that your ears will bleed in the car before any damage is done to the speakers. However having an UNDERPOWERED AMP IS NOT LIKE HAVING THE VOLUME TURNED DOWN. If you try to achieve more volume than it is capable of producing CLEANLY you will be chopping off the signal at the top and bottom of the wave sending a square wave that doesn't allow the speaker to accelerate and decelerate in a smooth manner like a typical sinusoidal signal would. It causes the speaker to jerk back and fourth making a distorted noise and possibly causing mechanical damage to the speaker.

An OVERPOWERED amp will make clean sound all the way until it starts to fry the wires in the speaker or the speaker begins to hit its maximum excursion (bottoming/topping out) but these failure modes occur at much much higher volumes than a CLIPPING failure would.

2/5/2008 10:41:55 AM

those components can handle 10-100W rms countinuous, and the rears i ordered are rated at 60W continuous.

I think a 70Wx4 like the Alpine MRP-F450 would be plenty. 2 more questions.

1. Speaker baffles worth it or not? I've read they aren't in most cases.
2. what am i looking for when adjusting the gain on an amp?

2/5/2008 10:57:22 AM

baffles are worth it if the window seals leak water inside the door. Also, if you use baffles, cut a hole in the bottom of them to keep from losing the lower frequencies while still keeping the speaker dry.

2/5/2008 11:48:23 AM

Quote :

"However having an UNDERPOWERED AMP IS NOT LIKE HAVING THE VOLUME TURNED DOWN."

yes it is. i don't care what amp you have pushing a pair of speakers whether it's 20w or 1000w, at, let's say, volume 10, the speakers are receiving the same wattage (obviously if the gain is set to match the radio's output).
you are correct in your description about what happens to speaker when it is sent a clipped signal. in layman's terms, it's called distortion which is very audible to the ear. once you hear distortion, turn the volume down some and the speakers won't blow. it actually takes a lot of abuse to blow a speaker by underpowering it. if it happened quickly, 95% of the cars on the road today would have blown speaker.

Quote :

"An OVERPOWERED amp will make clean sound all the way until it starts to fry the wires in the speaker or the speaker begins to hit its maximum excursion (bottoming/topping out) but these failure modes occur at much much higher volumes than a CLIPPING failure would."

correct. and by the time you realize you might be doing damage you've already fried the voice coils. this type of damage does happen quickly which is why it's dangerous to overpower a speaker.

2/5/2008 7:43:08 PM

Quote :

"those components can handle 10-100W rms countinuous, and the rears i ordered are rated at 60W continuous. I think a 70Wx4 like the Alpine MRP-F450 would be plenty. "

so would my rears be safe then?

2/5/2008 8:04:05 PM

yeah you should be fine since it sounds like you really don't want to jam that hard anyway. i'd still recommend just replacing the radio and speakers first just to see how you like it. it'll save you time and money if you find out it's plenty loud.

2/5/2008 8:33:26 PM

OK, so i bought the Alpine MRP-F450 amp.

70W RMS x 4 at 4ohms


slowly piecing it together...

2/6/2008 3:57:23 PM

Dude its going to sound awesome man.

you have me looking @ amps and speakers again.

2/6/2008 4:01:27 PM

haha yeah i've caught a bug.


I've got it bad too, cause i'm going to Nashville at the end of march so i want to be able to have the navi and dvd stuff all squared away for that trip.

and i talked myself more and more into it b/c since they totaled my jeep i didn't have to pay that huge deductible

2/6/2008 4:03:39 PM

Damn man.

bittersweet i guess

do you know anyone going to bonnaroo?
I really want to go this year i think led zep is supposed to be playing it.

2/6/2008 4:08:03 PM

bittersweet symphony, this life


but, nah dont know anyone going to bonaroo. know a couple going to langerado down in florida

2/6/2008 4:48:31 PM