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View Full Version : Stereo Speaker and Amp questions????


prostar205
01-11-2007, 07:16 PM
I will be upgrading the speakers in my boat this winter. I plan on going from the stock Clarion CM1632s to four (4) JL M770-CCS for the interior and four (4) M770-TCS for the tower.

Here are my questions:

1) Can I run all 8 speakers from my Kicker KX850.4 which puts out 180W RMS per channel at 2 ohms at 12.5V?

or

2) Would it be better to run the four tower speakers from the KX850.4 (one speaker per channel) at 4 ohms. At 4 ohms, the KX850.4 puts out 90W RMS per channel.

The JLs are rating for 100W RMS at 4 ohms.

If I go with option 2, I would pick up a Kicker KX650.4 to run the four interior speakers.

I also have a Kicker KX600.1 for my 12" L5 sub.

Finally, the whole system is powered from two Blue Top Optima batteries wired in parallel.

I have a seperate battery as the "house" battery.

Thanks for your thoughts????

TX.X-30 fan
01-11-2007, 08:24 PM
Are you running a stock alternater, if so add up all the amps and make sure your alt. can output enough first. Sounds like the battery setup is fine. The stock alt. is 70 amps or so, when i was adding amplifiers we quickly ran out of juice.

nuckinfutz
01-11-2007, 09:18 PM
option 2, you should be fine.

prostar205
01-12-2007, 02:25 AM
Are you running a stock alternater, if so add up all the amps and make sure your alt. can output enough first. Sounds like the battery setup is fine. The stock alt. is 70 amps or so, when i was adding amplifiers we quickly ran out of juice.

I had the alternator upgraded to output 105A. I also upgraded all of the wiring to and from the alternator. The stock alternator on my L-18 only put out 51A. For a big block that just seems wrong.

prostar205
01-12-2007, 02:26 AM
option 2, you should be fine.

I was really hoping you would say I'd be fine with option 1.

I know running the amp at 4 ohms is better and creates less heat when compared to running it at 2 ohms.

Diesel
01-12-2007, 09:31 AM
Option 1 gives you more power/volume and the KX series can certainly handle the load. Any increase in THD is negligable in a boat at 2ohm stereo. I've done it both ways and there is no need to add an amplifier and increase draw.

prostar205
01-12-2007, 10:56 AM
Diesel -

Is it going to hurt the JL speakers to hit them with 180W RMS when they are only rated for 100W RMS at 4 ohms. Or, because I am running them at 2 ohms, does that double their RMS to 200W?

TX.X-30 fan
01-12-2007, 11:49 AM
Diesel -

Is it going to hurt the JL speakers to hit them with 180W RMS when they are only rated for 100W RMS at 4 ohms. Or, because I am running them at 2 ohms, does that double their RMS to 200W?


I think my jl separates are rated at 150 per, so 180 should not be a problem as long as its clean power with low distortion. I used the jl slash 2/300 amps to run each pair of speakers. I run 4ohm speakers (dynaudio) in my home theater opposed to the norm which is 8. The amp is 300 into 8/600 into 4, I assume its the same with car stuff.

nuckinfutz
01-12-2007, 11:53 AM
Diesel -

Is it going to hurt the JL speakers to hit them with 180W RMS when they are only rated for 100W RMS at 4 ohms. Or, because I am running them at 2 ohms, does that double their RMS to 200W?


Youll know when there getting hurt. I have stuck alot more power to lesser speakers. Its only when you get to the greater volumes that they will scream NO.

Diesel
01-12-2007, 12:07 PM
Diesel -

Is it going to hurt the JL speakers to hit them with 180W RMS when they are only rated for 100W RMS at 4 ohms. Or, because I am running them at 2 ohms, does that double their RMS to 200W?

It does not work that way. Each individual speaker will not get 180W. When wired parallel they act as one 2ohm resistor and the power is split between the two drivers at each channel.

It is much safer to overpower speakers than to underpower. The JLs will scream at 2ohm stereo and you can set your gains to protect the speakers if you are worried. A properly set up system will allow you to turn the volume up all the way and hear zero distortion.

The only reason you would want to add the additional amplifer is to have complete LRFR control of your system. Which in a boat is pretty pointless if you ask me.

prostar205
01-12-2007, 02:39 PM
The only reason you would want to add the additional amplifer is to have complete LRFR control of your system. Which in a boat is pretty pointless if you ask me.

This is exactly what I needed to hear. I guess I will use what I have and hook the JLs up and see how they sound.

One more question:

One of the tower options I am looking at is a fiberglass enclosure that uses 3 pairs of the JL M770-TSC speakers. How would I wire 3 pairs of those speakers into 2 channels of my KX850.4? If I wire three speakers in parallel, then would that drop the resistance below 2 ohms?

prostar205
02-09-2007, 01:26 AM
Bump

Bump

Bump

Diesel???? Anyone have an answer to my question regarding the correct way to wire 3 pairs of JL M770s into 2-channels of a 4-channel amp?

prostar205
02-14-2007, 03:49 PM
Another Bump.......

nuckinfutz
02-14-2007, 04:00 PM
Sorry dude, but there is no correct way to wire 6 speakers to 2 channels.

You can series them, but you will notice great volume loss as well as significant quality drop due to X-overs in series dont like each other.
the correct way... buy another 4 channel amp.


Sorry to be the bearer of bad news.

prostar205
02-14-2007, 04:07 PM
Thanks!

I have seriously thought about that.

How's your winter going?

I've been researching tower speaker options - it seems the more I research, the more confused I get.

nuckinfutz
02-14-2007, 04:45 PM
My winter is going great!

Im relocating to San Diego! No more winterizing the boat my friend!!!

Im having a hell of a time finding a good place to store the boat thats close to where I am.

prostar205
02-14-2007, 05:12 PM
Have fun is SD. It is beautiful down there.

Diesel
02-14-2007, 05:22 PM
Another Bump.......

Sorry I missed this. nfz is right.......there is no good way. You can do it but power will suffer considerably.

JBaker
02-22-2007, 04:44 PM
Option 1 gives you more power/volume and the KX series can certainly handle the load. Any increase in THD is negligable in a boat at 2ohm stereo. I've done it both ways and there is no need to add an amplifier and increase draw.

Sorry Diesel, but you are mistaken. Option 1 would not give more power/volume. Each individual speaker would actually receive less power and thus put out less volume.

Also, there is no such thing as an amplifier that can fully double its power by cutting output impedence in half. So if your amplifier runs 90W RMS at 4 ohms, it can't actually do 180W RMS at 2 ohms. Hoping for 140-150W would be more realistic.

That being said, unless you are going to absolutely CRANK it, option 1 should be just fine-especially since you have a sub. Filtering out the low end on your 4 channel will make it work a lot less.