04 chevy tahoe sound upgrade

Let me start off by saying since this is my first post that this is a great site and very informative, been reading for the past month or so and finally need to ask a couple questions.

I'm doing a sound system upgrade for a good buddy of mine on his 2004 Tahoe w/ On-Star and Bose on board and have run into a little snag. This is what I've done so far.

Successively upgraded the head unit w/ a JVC KW-AVX720 7" DVD touchscreen. Installed GMOS-04 and  PERIPHERAL PESWIAKJC and everything works fine. He already had sub's (2 - CVR12's) and mono amp (PG Oct 15.1) so i just built a box and all that works fine.

Now he wants to upgrade the sound by adding a amp and tweeters and just use the factory Bose as mid's ya might say.  The problem is when i plug in the RCA cable into the back of the HU for the amp to the tweeters it loses the output to all the factory Bose speakers. My goal here is to retain the factory Bose speakers and add the amp/tweets. Also the amp is a 4 ch. amp and the HU only has 1 set of RCA outs (rear) for adding amps, will this be a problem? Thanks for any and all help.

Scott

On the GMOS-4, did you use the RCA outputs or the speaker outputs ?

?? Why did you do that.... anyway, if you used the RCA input for the GMOS-4 you should have plugged the JVC FRONTS & REARS into the RCA jacks provided. If your wanting to add an amp to the system to power new tweeters, you can not use the GMOS-4 to do this because it's taking the RCA inputs from the deck to use as a signal input. What you will need to do is wire in a ALO-648 and have the JVC speaker wires go to this LOC and this will free up the RCA's to go into the 4 channel amplifier. This will still allow the Bose system to have an input from the JVC deck while having an output signal go to the 4 channel amp from the JVC deck.

If no RCA outputs are available, use the Metra line output converter part #ALO-648 (SOLD SEPARATELY).

Maybe we are on different pages here.

This head unit only has a single RCA for sub amp and 1 set of rca's out for other amps. This is the output i need to use for my tweeter amp. I used the JVC harness to make all connections to the GMOS-04. Am i confused or is there a better way of doing this?

Velocity Motors wrote:

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?? Why did you do that.... anyway, if you used the RCA input for the GMOS-4 you should have plugged the JVC FRONTS & REARS into the RCA jacks provided. If your wanting to add an amp to the system to power new tweeters, you can not use the GMOS-4 to do this because it's taking the RCA inputs from the deck to use as a signal input. What you will need to do is wire in a ALO-648 and have the JVC speaker wires go to this LOC and this will free up the RCA's to go into the 4 channel amplifier. This will still allow the Bose system to have an input from the JVC deck while having an output signal go to the 4 channel amp from the JVC deck.

If no RCA outputs are available, use the Metra line output converter part #ALO-648 (SOLD SEPARATELY).

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This head unit has 4 pair of speaker wires and 3 channel preamp, 1 sub woofer preamp and 2 (right and left) RCA preamp outputs.

[url=https://www.crutchfield.com/p_105WAVX720/JVC-KW-AVX720.html?tp=20217&tab=features_and_specs]JVC KW AVX720 specs[/url]

I used the 4 pair of speaker wire from the HU to the GMOS-04 interface. I used the sub woofer preamp for the mono amp for the sub's. I have the 1 pair of RCA preamp left for the 4 channel amplifier for the tweeters. Can i do this? how? When i connect the RCA cable to the one and only preamp left i loose signal on the 4 pair of speaker wires thats used to connect to the GMOS-04. And how or will that 1 set of RCA preamp out be able to to be used for the 4 channel amp for the tweeters?

Is there anyone that has a solution to my problem? I need to add this 4 channel amp to this setup.

When you plug the RCA jacks into the deck, do you lose only the rear speakers or all speakers quit playing?

Does the GM-OS4 have an amp turn on wire to turn on the factory amp?   Check the voltage on this wire with the new amp and RCAs connected.

I have never seen a deck that would turn the speaker wires off when you connect RCA cables.  I am thinking that the remote voltage is dropping with the addition of the second amp.  This will be a simple fix with a relay if this is what is happening.

i am an idiot wrote:

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When you plug the RCA jacks into the deck, do you lose only the rear speakers or all speakers quit playing?

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All Factory speakers are lost, i keep the mono amp/subs. Which the head unit has a single ch. sub woofer out RCA.

]Does wrote:

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the GM-OS4 have an amp turn on wire to turn on the factory amp?

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Yes and i used the HU remote start wire for this, the mono and future 4 ch. amp.

]Check wrote:

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the voltage on this wire with the new amp and RCAs connected.

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This is the deal and may very well be my problem being nothing was connected to the amp RCA end. When i installed the mono amp and subs i went ahead and ran all the new 4 channel cabling to its location, The amp is not here yet, on it's way. Long story short, while i had the vehicle all apart i went ahead and connected the RCA for the new amp to the head unit to save me from having to get back into it to save some time once the new amp arrived. Thats when i lost all factory speakers so i had to unplug the RCA's. Question though, the only RCA outs i have is the 1 set on the HU that say "REAR OUT" will i be able to get the correct signal to the 4 channel amp with just the rear 2 channel signal? I will check the voltage when i get the vehicle back to install the new amp, but being the remote wire was cutting on the mono amp my thinking is that is not the problem and the fact that the remote is not even trying to power the new amp yet. Sorry for rambling, hope my explanation is not confusing?

Is it possible the amp end of the RCA cable was touching together or ground when i connected it to the HU is what caused to loose signal to the stereo signal out to the factory speakers?

]I hav wrote:

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never seen a deck that would turn the speaker wires off when you connect RCA cables.  I am thinking that the remote voltage is dropping with the addition of the second amp.  This will be a simple fix with a relay if this is what is happening.

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Actually I'll end up with 3, factory, mono and 4 ch. would it be best to add the relay on the remote signal to start all 3 amps?

Thank you very much for your response.

There will not be a lack of voltage without the amps connected.  Get a known good speaker and connect it to one channel of the radio.  Plug the RCA jacks in and see if that speaker cuts out. 

If you are not worried about being able to fade front to rear, the one set of RCA jacks along with a pair of Y adapters will work for you.

I will have the Tahoe back on Thursday of this week. I will post back my findings.

Thank you very much for your time, it's been much appreciated.