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Experiment with using car amplifier and sub in home theater.

Dr.Lakshay

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#1
Hi,
Sometime back I got this idea of trying out my car audio setup (amplifier and subwoofer) in my home theater with my Sony avr.
So I recently bought a 12v 50 amps smps to power the amp.
I set everything up and the most annoying thing is happening.
There is a continuous hum in the subwoofer. I tried changing the rca wire, the power outlet but no resolution found.
One peculiar thing is that there is no hum when no rca leads are attached. But as soon as I attach rca leads to the rca input of the amplifier, the hum starts.
If anyone knows any resolution to this problem please help me out.

Thanks and regards
Lakshay Goel
 
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arj

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#3
Maybe its a ground loop ? can you connect a wire between the metal case of both of the RCAs ? that worked for me when using my SUT
 

Dr.Lakshay

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#4
Maybe its a ground loop ? can you connect a wire between the metal case of both of the RCAs ? that worked for me when using my SUT
By between both the rca do you mean connecting both the ends of the rca, ie avr and amplifier end?
 

reubensm

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#5
What arj meant was to connect one end of a wire to the metal casing of the amp ensuring that electrical contact is made. The other end is to be connected to the ground of the RCAs on the amplifier side.
 

Dr.Lakshay

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#8
Looks like a ground loop. Use an isolation transformer.
If it was ground loop shouldn't it disappear if I use the same socket for both my avr and the sub amp? Because it doesn't disappear if I do so.
Also the hum is present even if the AVR is turned off and only the sub amp is on. But as soon as I remove the rca cable the hum stops.
 

Kannan

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#10
Is your AVR power plug 3-pin or 2-pin
 
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edjamesx

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#11
Hi,
Sometime back I got this idea of trying out my car audio setup (amplifier and subwoofer) in my home theater with my Sony avr.
So I recently bought a 12v 50 amps smps to power the amp.
I set everything up and the most annoying thing is happening.
There is a continuous hum in the subwoofer. I tried changing the rca wire, the power outlet but no resolution found.
One peculiar thing is that there is no hum when no rca leads are attached. But as soon as I attach rca leads to the rca input of the amplifier, the hum starts.
If anyone knows any resolution to this problem please help me out.

Thanks and regards
Lakshay Goel
Try connecting RCA from other sources instead of AVR. Was Sub working fine from your car setup ?. Anything damaged while transporting?
 

Dr.Lakshay

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#12
Is your AVR power plug 3-pin or 2-pin
The AVR power plug is 2 pin. I am using it with a step down transformer.
Try connecting RCA from other sources instead of AVR. Was Sub working fine from your car setup ?. Anything damaged while transporting?
Will try rca from other sources. Sub was working fine in the car. No damage in transporting. I will try my other car amp too just to check.
The RCA cable is completing the ground loop. This problem is fairly.well.documented. Bit of googling should help.
That was my first approach. And there were some suggestions like flipping the plug, using same socket for avr and amp. Trying other sockets in house. I tried them and it didn't help. So came to the forum for further help so that if someone might have faced the same issue could guide me.
Could you please explain me in layman's words what "rca cable is completing the ground loop" means?
 

Kannan

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#13
The AVR power plug is 2 pin. I am using it with a step down transformer.
I presume you are using a 3-pin power connector on your 220 to 12 volt power converter.
It will have a connection each for line, neutral and earth in its 220 section.
All the three should be appropriately wired to your mains socket.

Now see if there us a separate earth connector on the rear of the AVR.
If yes, then connect a wire between that and the earth connector in the 220 to 12 volt converter.
If not, then connect a wire from the earth on the 220 to 12 converter to anywhere on the body of the AVR (you can even tighten it to any of the screws.

It should take care of the humming if the earth in your house in pukka
 

Dr.Lakshay

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#14
I presume you are using a 3-pin power connector on your 220 to 12 volt power converter.
It will have a connection each for line, neutral and earth in its 220 section.
All the three should be appropriately wired to your mains socket.

Now see if there us a separate earth connector on the rear of the AVR.
If yes, then connect a wire between that and the earth connector in the 220 to 12 volt converter.
If not, then connect a wire from the earth on the 220 to 12 converter to anywhere on the body of the AVR (you can even tighten it to any of the screws.

It should take care of the humming if the earth in your house in pukka
Thanks a lot sir. Will try it out and update.
 

Dr.Lakshay

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#16
Hello everyone. Thanks for your feedback.
I got a replacement for the smps and also I changed the amplifier to my other car amplifier. Now I don't know if the problem was with the amp or the smps but it has been completely resolved and I am enjoying the subwoofer now. I do not intend to try that amp as this is the amp I will be using for long term in this setup.
I didn't have to do anything extra. Like grounding the AVR or the rca.
 

Dr.Lakshay

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#18
Could you please share some pics of the subwoofer, the amp and the SMPS..
Sure will do.
I just have the pics of smps. Will put em up right now.
Will upload the whole setup in some time. It's a little clumsy right now. Will have to clean it up.
 

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Dr.Lakshay

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#20
I hope you bought the 30amp model. Also set the output to 13.2 volts
It's 50amp model. Have set it to 13.75. IMG-20181028-WA0074.jpg
It can go upto 14.75 but I don't want to take it to that as I fear to damage the smps.
It is bloody cheap as compared to meanwell. It cost me 2200rs.
 
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