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Suggestions for Fosgate installation....

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=9416
Printed Date: August 06, 2025 at 11:29 PM


Topic: Suggestions for Fosgate installation....

Posted By: Macovial
Subject: Suggestions for Fosgate installation....
Date Posted: February 12, 2003 at 1:42 AM

I have a Fosgate 700x 4 channel amp with 2 MTX 8000 10 inch subs. Any suggestions as to how I can get the most power out of the amp to kick those subs H A R D ? I'm not sure if I should bridge it according to the manual or just bridge it, one sub hooked to the front outputs and the other sub hooked to the rear outputs since it's a 4 channel amp. And should I wire the subs in parallel or in series?

Any help would be appreciated.

- Macovial



Replies:

Posted By: wvsquirrel
Date Posted: February 12, 2003 at 3:25 AM
need the model number of the amp or the ohms per channel.  also need the ohms of the subs

-------------
Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com




Posted By: Macovial
Date Posted: February 12, 2003 at 2:35 PM
The model number of the amp is a 700x

87.5 W X 4 @ 4 Ohms RMS
175 W X 4 @ 2 Ohms RMS
350 W X 2 @ 4 Ohms Bridged RMS

And the subs run at 4 ohms each.

Thanks,

- Macovial




Posted By: wvsquirrel
Date Posted: February 12, 2003 at 9:35 PM

I'd suggest running one sub bridged on the Left channels (left and right), and 1 bridged from the Right channels (left front / rear and right front / rear).  You don't need to worry about parallel or series because you are wiring the subs to different channels independently.  Even though they will be bridged, sub1 will never be connected to the right 2 channels, and sub2 will never be connected to the left 2 channels.  If you were running a 1 or 2 channel amp that was 2 ohm stable, then you would wire the subs in parallel giving you a 2 ohm load for maximum output.

in response to "I'm not sure if I should bridge it according to the manual or just bridge it, one sub hooked to the front outputs and the other sub hooked to the rear outputs "... I just checked the manual (page 8) for 2 channel wiring of the 700x, and bridging 1 sub to the left and 1 sub to the right is how Rockford recommends.  So I'm not really sure what you were asking because both of your scenerios (the manual vs. your description) appear to be the same

Make sure to read the notice from Rockford concerning your amp... https://www.rockfordfosgate.com/ez2/fcsscripts/ExternalFiles/Rockford/2002/Amplifiers/LIT4216_RCA4Ch_NOTICE.pdf

And this should be the manual for it as well... https://www.rockfordfosgate.com/ez2/fcsscripts/ExternalFiles/Rockford/2002/Amplifiers/MAN3771C_4ChPunch_MAN.pdf



-------------
Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com




Posted By: Macovial
Date Posted: February 12, 2003 at 10:07 PM
Excellent reply! I appreciate you doing this for me. What I meant about

in response to "I'm not sure if I should bridge it according to the manual or just bridge it, one sub hooked to the front outputs and the other sub hooked to the rear outputs "...

This is the speaker output.... (ROCKFORD RECOMMENDATION)

LR+ LR-   RR+ RR-    B+ GND     LF- LF+   RF- RF+

LR+ plus LF- = BRIDGED LEFT
RR+ plus RF- = BRIDGED RIGHT

My question is.. can this be done?

LR+ plus RR- = BRIDGED LEFT
LF- plus RF+ = BRIDGED RIGHT

posted_image - Macovial




Posted By: wvsquirrel
Date Posted: February 12, 2003 at 10:56 PM

I gotta be smok'n something 'cause my reply was incorrect.  Rockford's suggestion is bridging left and bridging right (not front and back like I said before).  Sorry 'bout that. I've already edited my last post, so it should read correctly now.

I thought that's what you were thinking, but I wasn't sure.  Actually, Rockfords suggestion is for:

LR+ plus LF- for 1 sub, and RR- plus RF+ for the other

What you're asking for is bridging Front and Back, instead of Left and Right.  It should work (their 3 channel wiring diagram shows LR+ plus RR- for 1 sub), and it should be LF- plus RF+ for the other sub.  So on that you are correct.  I'm forced to ask why you would want to do this though?  Most people running 2 subs would prefer to have balance in the subs for the stereo effect, not a fade affect.  So I would still suggest using Rockfords method of LR+ plus LF- for 1 sub, and RR- plus RF+ for the other



-------------
Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com




Posted By: Macovial
Date Posted: February 13, 2003 at 3:02 PM
I was just curious if the setup in question was possible. That's all there is to it. Asking you all this information was "doing my homework" while my amp was in delivery from Rockford Repair and now it's back in my living room, awaiting installation. Now I know what to do.

I do have ONE more question. I ordered a 1.0 Farad digital power capacitor and it did not include a resistor for charging it up. How do I charge it up and what specific resistor is it talking about in the instructions? I went to the local audio place and they mumbled something and said I could get it from Radio Shack. I couldn't actually get the exact information out of them and I am wondering if you could help me out with that as to what part I will need and instructions on how to charge that sucker up.

- Macovial

If you're deaf, it doesn't matter how loud it is!




Posted By: wvsquirrel
Date Posted: February 13, 2003 at 10:44 PM
https://www.the12volt.com/installbay/display_topic_threads.asp?ForumID=2&TopicID=3575

-------------
Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com





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