rockford’s 3 channel from 2channel amp?

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=19234
Printed Date: May 19, 2024 at 5:08 AM

Topic: rockford’s 3 channel from 2channel amp?

Posted By: Ketel22
Subject: rockford’s 3 channel from 2channel amp?
Date Posted: September 23, 2003 at 8:59 PM

https://www.rockfordfosgate.com/rftech/library/2000/3_Amplifiers/MAN2616A_PowerAmp_MAN.pdf

can any body explain what is trying to be done on page 20 of the manual? and also the ohm load that would be on each channel?

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Replies:

Posted By: bberman1
Date Posted: September 23, 2003 at 9:22 PM

They are running a tri mode configuration; here is a good tutorial https://www.eatel.net/~amptech/elecdisc/trimode.htm

Posted By: Ketel22
Date Posted: September 23, 2003 at 11:04 PM

thanks for the link im still lost though. I am using the rockford 1000a 2channel amp if i hooked my three infinity kappa's 12.1 to the amp would one of the subs have a greater rms from the amp than the other two? what would the total load be on each channel if the subs a svc 4ohm?

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Posted By: Sweekster
Date Posted: September 24, 2003 at 9:49 AM

In that setup they are running two speaker from two channels and then one speaker from both channels (bridged). It's kinda like using the amp to power 2 6x9 speakers and running a sub from both side. It would (for example) drop the load on the 6x9's to 2 ohm and keep the sub at 4 ohms since you're using the positive on one channel and the negative on the other to run the sub. In other words, its like running a sub in bridged mode but you also add a speaker to each channel.

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Posted By: wvsquirrel
Date Posted: September 24, 2003 at 2:03 PM

Just remember to keep a minimum of a 2ohm load on the stereo channels, and 4ohm on the bridge

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Squirrel
"No more Cpt. Kirk chit chat"
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Posted By: Ketel22
Date Posted: September 24, 2003 at 8:51 PM

thank you squirrel i can understand that

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Posted By: wvsquirrel
Date Posted: September 25, 2003 at 11:45 AM

no prob

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

Posted By: the12volt
Date Posted: September 25, 2003 at 12:40 PM

Impedance is relative to frequency. The diagram doesn't show the impedance of the stereo speakers nor does it show the impedance for the speaker wired in mono, it only shows the lowest recommended speaker impedance for each. If all speakers had a nominal impedance of 4 ohms and the high pass and low pass frequencies for each filter were the same, for example 80Hz, the amplifier would see a 4 ohm load per channel from 80Hz and up and a 2 ohm load per channel from 80Hz and down. If the low pass frequency for the speaker wired in mono was 100Hz and the high pass frequency for the speakers wired in stereo were 80Hz, the amplifier would see a 1.33 ohm load per channel between 80Hz and 100Hz, and from 100Hz and above it would see a 4 ohm load per channel, and at 80Hz and below it would see a 2 ohm load per channel. Obviously if the amplifier is not stable below 2 ohms per channel then overlapping crossover points in this configuration using all 4 ohm speakers would not be recommended.

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