# Low budget surround sound set up question



## Ermergerd (Oct 16, 2012)

ok so I finally have space to set up my first surround sound set up. I managed to pick up a Sony STR DG710 receiver for cheap. I mainly got it because it had HDMI inputs and it was newer than what I had.

I have a flat screen that has HDMI inputs

Being into car stereos since I was able to drive, I have car amps/subs available. I am currently converting a computer PSU into a 12v power source to power the car amp.

The problem I'm having is, is how am I supposed to use the same input on the receiver (HDMI Video 2) with the RCA cables from the car amp? Will I not be able to use the HDMI inputs on the receiver? Keep in mind this is a low budget set up and I'm using what I have available to add some bass. :help:

thanks - Josh


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## nova (Apr 30, 2006)

I'm not quite sure what you're trying to do...Why would you connect the amp to an input on the receiver?
Not sure exactly what you are working with but typically you would connect the receiver and TV via HDMI and the speakers to the receiver. If your want to add an amp it would be connected via the receiver pre-out to the amps input. The STR DG710 does not have audio pre-outs other than the sub. To connect an amp to that receiver you will need some type of line level converter. The Sony does have a subwoofer pre-out if you are only looking to add a sub powered by your car amp.


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## Ermergerd (Oct 16, 2012)

How else is the signal supposed to get from the car amp to the receiver if it isn't hooked up?

A friend of mine used a car amp/sub set up on his home theater many years ago and I thought it was a pretty cool idea. 

I completely forgot about that sub output on the back of the receiver do I'll try that


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## NBPk402 (Feb 21, 2012)

Ermergerd said:


> How else is the signal supposed to get from the car amp to the receiver if it isn't hooked up?
> 
> A friend of mine used a car amp/sub set up on his home theater many years ago and I thought it was a pretty cool idea.
> 
> I completely forgot about that sub output on the back of the receiver do I'll try that


If your receiver doesn't have preamp outs you would need to get some converters to convert the speaker terminals to low level RCAs to hook up the car stereo amp. You would not hookup the car stereo amp to an input on the receiver. The amplifier outputs go to your speakers not to an input on your receiver...if you hook it up to an input on your receiver it is wrong.


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## Lumen (May 17, 2014)

I agree with Ron and Mark. You need to give your car amp the correct signal from the receiver, not just any signal. Connecting an audio signal from an HDMI cable to an RCA cable will not work. HDMI is encoded, so you would need some sort of decoder, like an HDMI switcher with legacy (RCA) outputs. Because of HDCP copy protection, you would only get a composite signal (1 Video, 2 stereo - left & right), The LFE (sub) channel would be lost. Instead, multichannel audio would be down-mixed.


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## nova (Apr 30, 2006)

Ermergerd said:


> How else is the signal supposed to get from the car amp to the receiver if it isn't hooked up?


What signal do you have that goes from the amp to the receiver?

Your STR DG710 should be connected to the TV with an HDMI cable. 
Your receiver HDMI OUT to the television HDMI AV IN usually HDMI 1 or preferably HDMI (ARC) usually HDMI 2.
So i guess I'm a little confused as to what signal you are amplifying and sending to the receiver.


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## Chromejob (Feb 19, 2015)

Ermergerd said:


> How else is the signal supposed to get from the car amp to the receiver if it isn't hooked up?
> 
> A friend of mine used a car amp/sub set up on his home theater many years ago and I thought it was a pretty cool idea. ...


Um ... NO. 

Whatever reason he had for doing it was probably a bit misinformed, and what he ended up with is referred by old time computer folks as a "kluge." 

Unless you can tell us precisely you are trying to do with the car audio gear, I'd put it in the garage and leave it there. 

You need some kind of DVD, BD player which will no doubt connect to your Sony via HDMI IN. You can then hook the TV to the Sony the same way (HDMI OUT). These connections are digital content. Speakers next (you would've been better advised to start buying speakers for what you want, but s'okay, you can still soldier on with the AVR you bought).

IF the TV and the AVR are capable of HDMI-ARC, that's about all the cabling and amp that you need. If not, then a TOSlink or coax digital audio from the TV back to the Sony will allow you to listen to cable/broadcast TV on the HT setup. Once again, this is digital, and the car audio stuff is useless. 

Welcome to 2015. The likelihood of anything analog in your beginning HT setup is slim.  

So ... next questions?


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## willis7469 (Jan 31, 2014)

Ermergerd said:


> The problem I'm having is, is how am I supposed to use the same input on the receiver (HDMI Video 2) with the RCA cables from the car amp? Will I not be able to use the HDMI inputs on the receiver? Keep in mind this is a low budget set up and I'm using what I have available to add some bass. :help: thanks - Josh


 yep. Use the hdmi inputs. From the BD/cd player to the receiver. Then send the sub out(rca) from the receiver to your car amp. The signal goes from the receiver to the sub. Not the other way around. If your budget is zero, it'll be better than nothing. But I wonder if a real power inverter would be better.


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## Chromejob (Feb 19, 2015)

What is the car amp supposed to be doing? What is being used for a subwoofer?

I presume that a vehicle sub will not work in a home the same way, not even similarly.....


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## willis7469 (Jan 31, 2014)

Chromejob said:


> What is the car amp supposed to be doing? What is being used for a subwoofer? I presume that a vehicle sub will not work in a home the same way, not even similarly.....


 my understanding is he's powering a car sub with a car sub amp, using some left over stuff from previous builds. You presume correctly, in that it will not work the same way. The only reason anybody should do this is if they have the stuff and ZERO money. He said he wants to add some bass. It will do that, but it won't be deep, and it won't be linear. I don't think the criteria is going to be difficult to achieve.


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