Print Page | Close Window

amp/speaker selection

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=94057
Printed Date: April 18, 2024 at 1:07 PM


Topic: amp/speaker selection

Posted By: phil mcc
Subject: amp/speaker selection
Date Posted: May 19, 2007 at 1:23 PM

< style="FONT-SIZE: 14px; FONT-FAMILY: Verdana" nd="1">Ok I am on the beg for some help!

I have a 98 Jeep Grand Cherokee Laredo which I will be shortly be giving to my son as his first car.

It had a factory head unit with four factory speakers. One of the rear speakers is dead (checked by switching it for a front and it does not work there either!). So I decided to "ice" it up a bit for him!

I put a new head unit in it which works fine, and a colleague at work gave me a new 550 watt 2-channel AMP with 4 new three way 6 3\4" speakers which will fit the Jeep. He was clearing out after his son left for college and told me to get them fitted quick before his boy comes home for them - nice!

I also have a slightly used Pioneer 12" sub in a box.

The sub is rated 800 watts peak power (150 watts nominal). The four speakers are rated 135 watts peak each (50 watts RMS).

I know I can run the sub on it's own in bridged mode on this amp. I also know I can parallel off the pairs of speakers (left and right) and use this amp for them, albeit that I would lose fade control front to back.

I have also seen a wiring diagram somewhere for using the two channels for the speakers and also bridging for the sub but this seems dodgy.

I think therefore that I need another amp. My questions are as follows:-

If I can use a 2-channel for the door speakers should I use the one I have or would I be better using that for the sub and getting another one for the speakers bearing in mind the ratings of everything?

Is the 550 watts enough to drive the 4 door speakers?

Would it need to be a four channel for the door speakers to give me the fade control back?

Will the fade even work if I am using the low level RCA output from the head unit to the amp?

If I use this amp for the door speakers, do I just need to buy another bridgable two channel amp for the sub woofer rated at up to 800 watts peak output?

Anyone know where I can find a formula for all this stuff (and the money to finish it now I started it? :-)

Thanks in advance - if you can't answer all of them at least answer some of them!!!! Cheers.




Replies:

Posted By: zhalverson
Date Posted: May 19, 2007 at 1:47 PM
phil mcc wrote:

< style="FONT-SIZE: 14px; FONT-FAMILY: Verdana" nd="1">Ok I am on the beg for some help!

I have a 98 Jeep Grand Cherokee Laredo which I will be shortly be giving to my son as his first car.

It had a factory head unit with four factory speakers. One of the rear speakers is dead (checked by switching it for a front and it does not work there either!). So I decided to "ice" it up a bit for him!

I put a new head unit in it which works fine, and a colleague at work gave me a new 550 watt 2-channel AMP with 4 new three way 6 3\4" speakers which will fit the Jeep. He was clearing out after his son left for college and told me to get them fitted quick before his boy comes home for them - nice!

I also have a slightly used Pioneer 12" sub in a box.

The sub is rated 800 watts peak power (150 watts nominal). The four speakers are rated 135 watts peak each (50 watts RMS).

I know I can run the sub on it's own in bridged mode on this amp. I also know I can parallel off the pairs of speakers (left and right) and use this amp for them, albeit that I would lose fade control front to back.

I have also seen a wiring diagram somewhere for using the two channels for the speakers and also bridging for the sub but this seems dodgy.

I think therefore that I need another amp. My questions are as follows:-

If I can use a 2-channel for the door speakers should I use the one I have or would I be better using that for the sub and getting another one for the speakers bearing in mind the ratings of everything?

Is the 550 watts enough to drive the 4 door speakers?

Would it need to be a four channel for the door speakers to give me the fade control back?

Will the fade even work if I am using the low level RCA output from the head unit to the amp?

If I use this amp for the door speakers, do I just need to buy another bridgable two channel amp for the sub woofer rated at up to 800 watts peak output?

Anyone know where I can find a formula for all this stuff (and the money to finish it now I started it? :-)

Thanks in advance - if you can't answer all of them at least answer some of them!!!! Cheers.


More information on that equipment  would be nice, i.e. make and model.  Makes it easier to tell you how it will mesh up together.

Your options as i see it are:

1) Use your headunit to power the speakers and bridge your amp to your subwoofer. We will need more info. to tell you if it's ok to bridge your particular amp with this sub...

2)  Use your amp to power your speakers in parallel and buy a seperate amp (i'd suggest a "mono" amp) to drive your subwoofer.  If you were going to do that you would need to maker sure your amp is stable running a two-ohm load on each channel.  I wouldn't do this one personally.

3)  Buy a 4-channel amp to power your speakers and use your existing amp for the subwoofer.

4) Use the 2 channel amp to power the front speaker, power the back speakers off your headunit and buy a "mono" amp for the subwoofer.

One would be the cheapest.  2 i would suggest against. 3 would work well.  4 would be good too.





Posted By: phil mcc
Date Posted: May 19, 2007 at 1:55 PM

Thanks for that mate! 

I think the head unit only kicks out 4 x 16 watts rms so would the speakers not be a little underpowered?

Looking at option 3, I can use the 550 watt amp bridged to run an 800 watt sub. If I then add a 4 channel amp what size would it need to be to power the speakers at 135 watts eack peak and 50 each normal?

If I can get that bit right I think that is the way I will go.





Posted By: zhalverson
Date Posted: May 19, 2007 at 6:21 PM
Well first of all completely ignore max power ratings as they mean practically nothing.  Look at nominal, rms, continuous or whatever power ratings name the company chooses (it will be the lower one).  So the 4-channel amp needs to be around 50 x 4 watts rms to be a good match for those speakers.  Hook those babies up and make sure the amp is ok to handle that sub bridged you should be good to go.





Print Page | Close Window