Adding new speakers/sub/amp/DSP but want to keep HEAD UNIT???

Hey guys,

Need some help. I have my 2021 Tundra completely torn apart to put in sound deadening because I am upgrading the JBL sound system with basically new everything except the head unit. Based on the HU wiring diagram it sends a R/L +/_ signal to the JBL Amp and from there the JBL amp does the rest. I am getting rid of the JBL Amp (or I would like to) and want to tap into the R/L signal coming from the Head unit. I will assume it is a low volt signal because it is pre/amp (and I haven't had a chance to check the volts yet). So has anyone tapped into that speaker wire signal from the HU and converted it to simple RCAs (via speaker wire to RCA adaptor). I need RCA inputs to go into my DSP. From my DSP I can split the signal and send it to my 5 channel amp, via additional RCA cables. Any advise will be extremely helpful...god bless.

 

I may be wrong but the Factory JBL amp controls more than you think and I do not think removing it without the headhunt being replaced is an option.
I would reach out to James Randy Taylor His email is... Tech12volt@gmail.com
He builds systems specifically for the Tundra. He has a DSP amp that he wires, tunes and sells that plugs into the factory JBL amp.
There are tons of people that have this amp and swear by it. I just bought one myself.
He also sells custom boxes, subs, and speakers too.

 

Yes, I have been reading about all the people happy with 12Volts (James's) stuff. Based on the JBL amp wiring, it looks like the amp controls the signal to each speaker and the fading properties (but I dont see anything else), and I am okay with losing fade cuz I can control that thru my DSP. I am really hoping not to use the High Inputs from the JBL amp speaker wiring and would much rather just get rid of that thing and I already have everything for my install. Thank you for your response.

 

This is from one of the pages on AutoHarnessHouse.com here: 30-pin Subaru Harman Kardon and/or Toyota JBL Amp jumper - Splice Harness to add Subwoofer

"If you are adding an amplifier to your Harman Kardon/JBL vehicle, it will be necessary to tap into the audio signals at the output of the OEM amplifier. The reason for this is that the OEM amplifier will perform volume control and equalization functions that will not normally be performed in an aftermarket amplifier. Simply put, you won't be able to control the volume in your vehicle unless both the amp and headunit are installed and working in tandem."

Like @Bergy24 said I don't think you can remove one without doing the other, or, leaving the factory amp in place to perform volume control and equalization and tapping the signal post amp.

 

Thank you Snert. I have been reading a lot of your posts today. Your comment above is very interesting. I wonder how the JBL amp knows to increase/decrease volume? I would think that it has to get some sort of increase/decrease in signal (voltage) from the head unit. I dont know enough about this stuff to even make an educated guess.... Maybe tonight I will try to get a voltage reading reading from the W/R/G/B wires coming from the HU going to the amp to see if that signal increase/decreases voltage. My wife is not gonna be happy with me buying a new head unit....

 

Yeah I'm not super familiar with the JBL systems but I've anecdotally read other user's reports regarding the head unit and amp working in tandem. I would start by doing the exact same thing and test wires with a multimeter and see if voltage changes pre-amp when turning the amp up/down. I've literally never heard of/seen that in a system before but I'm by no means an expert. Only thing I can think is that somehow the head unit is sending a volume data signal to the amp and then the amp is doing the volume up down but again, I'm no expert and that could be completely wrong. AutoHarnessHouse is very reliable though and I would trust what they say but it doesn't hurt to verify because who knows, maybe that only applies to certain years of JBL etc.

 

Yeah, I have been doing some more research after your comment, which added to what Bergy said. It does, in fact, look like the HU sends some type of digital signal that is interpreted by the amp and the only work around to delete the amp is to use a device that uses the Idatalink Maestro technology, which the RF DRS1 uses, else you can use PAC AmpPRO AP4-TY13 Aftermarket Amplifier Interface. All these interfaces are just more chances for the signal to get compromised. Man this is frustrating because I am back to just buying a new head unit. BALLS.

 

I believe the amp only controls the door and rear speakers / sub in these systems. The head unit powers the dash speakers and would still have volume functions to those channels. Keeping the head unit is a choice, most who have been down that path will tell you they ended up replacing the head unit after hitting the brick wall of mediocrity with their sound systems.

 

In a non-JBL the head unit powers the dash corners, center, and rear tweeters, but in a JBL everything flows through the amp. You might be right about the volume control though I'm not sure if the dash is independent of the rest.

Can look at the full wiring diagram here: All Years Complete Audio System Wiring Diagrams | Toyota Tundra Forum

 

What is your ultimate goal? Any reason you don't want to use the DSP amp from Tech12Volt?

 

Wireless CarPlay is one quality of life you need to have. Replace that HU.

 

There is no particular reason, except that I have already purchased a DSP that I am favorable to and believed it would work pulling the signal from the HU. I am also not a fan of the head unit...at all. The GPS is very lethargic, the screen is small, and yes carplay has spoiled me. Thus I knew that I would be replacing the HU eventually, just didn't want to do it now, even though it makes everything so much easier and will provide a better signal. I currently have the entire cab taken apart to install sound treatment, and at this point I am so frustrated that I dont want to do any of this again. So, I guess getting a new HU just makes sense, as I throw up my surrender flag . Ultimately, what I am really wanting is a better more enjoyable full quality sound for our long trips we are planning on taking, and what that means is replacing all the JBL stuff. The unfortunate part is my wife is not happy because she really doesn't care about sound quality, so she thinks this is all for not. Yet here I am, looking at 4-10hrs drives and really wanting to enjoy those hrs spent 1) being able to hear her better (thus the sound treatment) and 2) being able to hear better and fuller music. We shall see.

 

I did sound deadener extensively on my doors and rear wall, probably won’t do the roof or floor cause man, what a pita. I also made block off plates for my doors which added a lot of time. You should be in good shape and yeah unfortunate about the head unit but with a new one and a dsp you should be tip top.