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installing two head units

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=41232
Printed Date: May 15, 2025 at 2:59 PM


Topic: installing two head units

Posted By: alw297
Subject: installing two head units
Date Posted: October 19, 2004 at 3:01 PM

Has anybody installed a second head unit piggybacked onto the existing one? I have many customers in particular UK spec Toyotas where a double DIN space is available and they ask if the original Toyota radio/cassette unit can be left working along with a new CD player underneath. I was thinking maybe the amp remote trigger could be used to switch a relay using 87a to power off the Toyota unit when the CD player is switched on. My concern is how to wire the speakers to both units. Could it be done using diodes?

Any help greatly appreciated.

BigAl

Halfords UK




Replies:

Posted By: jeffchilcott
Date Posted: October 19, 2004 at 4:44 PM
I try not to do this, but i have. I basically piggybacked all speaker connections and had the power source seperate, and fused. everything worked fine unless you tried to play both units at once.    you could use a relay to keep power only availible to only one source, I used a 3 way toggle switch so that both units couldnt see power at the same time

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place




Posted By: Ravendarat
Date Posted: October 19, 2004 at 6:43 PM

If you wanna go overboard and scare the living sh*t outta your customers you could use relays to seperate each speaker wire with a relay so it will only actually connect one set of wires at a time. When you throw a switch it would throw all the relays. Of course the look on your customers face would be pricless when he threw the switch the first time and like 10 relays started clicking around his dash. I dont see why the 3 way toggle switch wouldnt work except I dont know what kinda reprocusions could come from driving signal back through the deck that is not on. I would assume that since its off it wouldnt hurt it but like I said, I never tried.



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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer





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