No amp needed for mid's and high's??

[RickMar]

Hi,
Thanks for taking the time to check out this post.

I am totally confused of RMS-Ohms-Max Watts- Watts @ 2 and 4 Ohms to 2 and 4 channels etc.

Five years ago I wanted some nice sound in my SUV so I got rid of the stock cd/stereo and purchased an Alpine unit.
I had the stock speakers removed and had 4 Infinity 5"X7" reference speakers installed in the four doors.
I wanted a little bass so I had one 10" Infinity sub with box mounted in the rear.
The amp for the sub is a (2 channel) Audiobahn A4002T
Specifications
2 X 100 WATTS RMS
1 X 800 WATTS ACH POWER
800W Max, Intake Series 2-Channel Amplifier
RMS Power Output:
100 watts x 2 chan. @ 4 ohms
200 watts x 2 chan. @ 2 ohms
400 watts x 1 chan. @ 4 ohms Bridged
Max Power Output: 800 watts @ 2 ohms
Class A/B MOSFET Circuitry
PWM MOSFET Power Supply
Variable Bass Boost Control: 0-18dB @ 45Hz
Variable Low-Pass Crossover: 50-120Hz
Variable High-Pass Crossover: 50-750Hz
Signal-to-Noise Ratio: 100dB
Frequency Response: 10Hz-40kHz
Variable Subsonic Filter: 20-50Hz
THD: 0.02%
Phase Control: 0 or 180°
Input Sensitivity: 200mV-8V

The only thing the amp is used for is the bass of the sub.
Over the years I have heard some awsome sounding systems and figured I needed to get an amp for the (4) Infinity reference speakers to make the mids and highs more noticeable.
For my birthday my wife purchased a (2 channel) 800Watt Sony xm-ZR1252 amp .
I was told that the Sony was known to run HOT[/B and having 4 speakers (2 front)+(2 rear) I was informed I needed a (4 channel) amp.
I have been checking out the 4 channel amps for 3 days. And will be taking the 2 channel amp back for a refund tomorrow.
I am interested in the Kenwood KAC-X4R 1200W reference amp.

Today I stopped in to an auto sound installation store to have some questions answered about the specifications of the Kenwood KAC-X4R
(Watts @4 Ohms and Watts@2 Ohms) to the 4 speakers. I am totally lost with the technical stuff.
The sales associate listened to my system in the Mounty and after he turned down the bass to the sub...he told me I had plenty of mid's and high's and a 4channel amp. would not make much of a change in sound unless I had component speakers with (seperate tweeters) etc.
He also said that maybe that the bass was turned up all the way and it was drowning out the mid's and highs.
I thought to myself -what is the need for the sub if the bass needs to be cranked down.
Could one of you Pro's fill me in with any advice? I am looking for a nice sounding system and as you can tell I am totally confused. I can not understand why ...I need to turn down the bass to hear the mid's and high's If I do not need a 4 channel amp for the four speakers why do they sell 2 and 4 channel amps.
I am way on the "Dark Side Of The Moon" on this stuff
Any information will be appreciated.
Thank you.
Rick

 

[BrianDye]

What are your door speakers like? Are they 1 way, 2 way, 3 way? (One ways are like stock, just the speaker, 2 ways are the speaker then theres a 1-1.5" tweeter on it, 3 way is the same as a 2 way, with one more small tweeter)

The only thing an amp would do is make your speakers louder, just be sure to have a 2 or 3 way speaker, to get the crispest, highest sound. I have 3 way speakers, and 4 tweeters all around.

 

[RickMar]

Hi Brian,
Thank you for your reply, I appreciate it.
I have 2 way speakers with a small tweeter in the center.
They are Infinity Reference Speakers 5'X7".
They are almost identical to the new Infinity 6822CF reference speakers of today.
I just celebrated my 59th birthday making me kind of an "old timer"
I listen to Classic Rock - Pink Floyd, Dire Straits, Zepplin etc.
I have been looking to hear all the symbols and bells etc. in the background that seem to be weak.

Thanks again,
Rick

 

[nitro71]

I'm sure driving them with a amp would make them louder. If the speakers don't have a crossover try to find a amp that has a crossover built into it to block the bass from the 2 way speaks. I'm sure some of the audio guru's will chime in to help you more.

 

[BrianDye]

Yeah im not an audio expert by any means, but I do know alot, I have quite the setup in my 92, but I listen to rap, rock and the whole 9 yards...

If the speakers are 5 years old like your headunit, you might want to think about getting something new, also a new headunit would help, better sound processing and cd quality and all that good stuff.

I would look into a set of 3 ways, and maybe a set of 2 tweeters for your front doors, and make sure they all have crossovers, and then a nice little 4 channel amp to power it all...

 

[Anime]

The RMS/max/watts/ohms/channels thing is pretty easy, it just sounds complicated because so many companies fudge numbers to make something sound better to less educated consumers.

For most purposes, speakers have a 4 ohm impedance (resistance). You can save yourself a lot of hassle if you just worry about 4 ohms and wire your speakers/amps for 4ohms, since this is where most speakers/amps are most efficient.

Making an amp run at 2,1,etc. ohms by using 2 ohm drivers, or wiring the speakers a certain way (called series or parallel configurations), just makes the amp see that 2,1,etc ohm load. Usually, for each step (4 ohms to 2 ohms, 2 ohms to 1 ohm), the amplifier power doubles...but usually at the cost of sucking more power, the amp generating more heat, and very often making it less efficient (producing way more heat and sucking way more juice just to get twice the wattage output) Newer designs have changed this somewhat (lots of amps now run VERY cool at 2 and 1 ohm loads), but it helps illustrate the thinking behind ohms and all that.

RMS power is simply the continuous power an amp puts out, or the power a speaker can handle continuously, as in, 99% of the time. Max or peak power is the power an amp puts out or the speaker sees during the really LOUD parts of a song (each big bass thump, a really high note, etc.). Max power is typically 2 times RMS power. It's easy to get confused since a lot of companies are now using misleading specs (such as 40W RMS/160 MAX) that don't make a lot of sense when trying to match up with an amp. RMS power matters most, though. Go with that and you'll be good.


As for your setup, you can usually get away with running the speakers off the head unit or with lower power than the sub since the mids and highs don't need as much power to get the same volume level.

That said, an outboard amp usually makes at least some difference because putting the most power you can into a speaker makes it play clearer, and louder. If your speakers handle 50 watts RMS each, and your receiver is only giving them 20-25 watts RMS each, it's not pushing them to do what they are capable of. The other BIG benefit of an amplifer for the speakers (similar to that of the sub), is the ability to use a crossover to filter out certain frequencies. In the case of speakers, you filter out the frequences below 80-100Hz (whatever the subwoofer amp crossover is at), so your speakers only play everything above that. This makes the speakers play both louder and clearer because they aren't trying to reproduce bass, and all the power they are getting is going towards frequences they can do. This also means you can CRANK IT UP (but please, be safe) and have your speakers playing LOUD but very, very clear because all of the low frequences that would be distorting them are gone, and the sub is taking care of all those lows.

You may not have to get a seperate amp, though. Many new receivers have selectable "high-pass" crossovers so you can still use their internal amps and not get the distortion, and some newer receivers are high powered, putting out power similar to that of some 4-channel amplifiers. Seperate amps are still generally better.


You don't HAVE to get seperates to get the benefit of an amp. Car audio sales guys are great at talking people up into getting more gear, though. Seperates DO sound better (and handle more power) than drop-in 5x7's/6x8's, but theres a lot of wiring involved, not to mention how much more they usually cost!

If you want the benefits of an amp, go for it. You can get a good, brand name (Kenwood, JBL, Infinity, etc) 4 channel amp for your speakers. Just be sure the RMS power of the amp (per channel, at 4 ohms) isn't more than the RMS power handling of your speakers (each speaker, at 4 ohms). My guess is you'll need a 40W x 4 or 50W x 4 amp.

The Kenwood eXcelon KAC-X4R is a good amp (especially when you can get it for $200 rather than it's $599 list price), but it puts out 75-100 Watts per channel. Unless your infinity 5x7's handle 75W each (I'm thinking they don't), you would want to either get another amp to push them, or get different speakers that handle more power.