making a harness line output to low rca
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=138378
Printed Date: May 09, 2025 at 9:27 AM
Topic: making a harness line output to low rca
Posted By: gtr86
Subject: making a harness line output to low rca
Date Posted: January 30, 2015 at 1:51 PM
Making a harness, Line output to Low RCA levels into an amp. I have a standard 50 Watt head unit and wanting the values of the resistors to reduce the input safely into a RCA Low Level input for an amp.
Replies:
Posted By: tonanzith
Date Posted: January 30, 2015 at 2:13 PM
Just curious why not pick up a loc 80 or equivalent?
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Gary Sather
Posted By: oldspark
Date Posted: January 30, 2015 at 4:01 PM
Read up on resistive voltage dividers. (A series resistance x times the amp input's impedance where x is the desired reduction ratio. EG - 15-fold reduction into 10k inputs means a 150k resistor.)
Posted By: gtr86
Date Posted: January 31, 2015 at 3:29 PM
150K resistor at what wattage?
Posted By: oldspark
Date Posted: January 31, 2015 at 4:29 PM
Any Wattage. It'll be so small it doesn't matter.
NOTE that I am NOT saying a 150k resistor - that is an example only which is for speaker outputs to low signal levels, not line outs (which IM-inexperienced-O should be low enough anyway).
You have not given sufficient info for an answer. But FYI, the worst case Wattage for a 150k assuming 50W into 8 Ohms is ~3mW so even a 1/8W (125mW) resistor is more than enough. And it would be even less if dropping a Line Output.
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