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sir would you be generous enough to help me diagnose the problem or can guide me to a link which provides some insight for this problem.
i have 2 amps and today i disconnected one and found that the sound comes from all speakers .the two amps have different power cable .the 2 channel amp gets its rca from the aux out of gto 1004 .both amps have a common earth point

I am going to assume this.....

1. HU is connected to JBL 1004,
   
2. pass through channels of the JBL 1004 are connected to the a 2 channel sony amp which feeds the rear 2 speakers.
   
3. JBL 1004 is used to power subwoofer (2 channels bridged) and front speakers.

a. the aux out on the JBL has been provided so that a second amp can be used for the front speakers. Options like using the JBL 1004 for the front speakers (by using the HPF) and a monoblock for the sub or using the 1004 for a sub (using the LPF and bridging both channels) and a stereo amp for the front.

b. you obviously have an install issue. Either way electrical noise from the engine systems is entering the audio system. Since solution to these problems are not easily got over the internet (one has to hear and test various solutions) it is best to take your system to a good installer. In my expereicne, out of every 10 installers I have come across only 2 or 3 are really competent. You need to find one that is close to where you live/work and that is competent - word of mouth is your best option for this.

c. one of the best ways to tackle such issues is to undo the whole wiring. Then connect just one amp (say the JBL 1004). Connect front speaker, test. Connect rear speakers, test. Connect second amp and subwoofer, test. Between 2 tests make only one change so you can determine which component is the problem.

thanks navin sir. your assumptions are 100% right.do you think the connections should be changed so that the 2 channel supply the front compos or should i continue it with this way only.

i will go for the c option as i dont know any good installer in ludhiana.

i am also thinking of changing my hu for a one with 3 rca out .will changing that will also cause the noise to go away. as i am going for kenwood 7043 bt hu.

noise coming into audio does it happen from rca ,power cable or faulty earthing .generally which one is at fault

Sadly your best amp is the JBL 1004 (both in abiltiy to swing volts and sound quality). The Sony should be used for only your rear speakers like you have done.

One option is to temparirinly use the Sony for the sub and switch it for a monoblock when you have the funds.

If you are in Ludhiana why not contact LBM (he's in the Punjab too). I am sure there are good installers in Ludhiana.

a 3 RCA HU will allow you to connect all 4 amps directly to the HU. Yes it will reduce the number of connections and ground loops that you can run into but it is not a cure all. Install quality still needs to be good.

NAVIN sir yesterday i removed the rca for rear speakers. removed the ground and the fuse of the sony amp .now the gto 1004 was running only the comp still there was noise.

i cant connect sony to the bass tube of jbl as it will not be able to power the bass tube.funds are not a prob (some advantages of being a doctor) BUT i dont think i will need more bass than i have with the gto.

i think lbm is in faridabad not in punjab even then i will contact him .thanks again

Ok lets start with this...

HU to front speakers with no amps. Is there still any noise? If not then try a new set of RCA wire or borrow some from a friend. The noise is either coming from the HU or RCA wire. So before you start upgrading components lets eliminate the noise first.

Assuming the noise part is resolved....

I agree that 2 bridged channels of the GTO 1004 will provide enough watts to power the bass tube. THat is what I was hinting at. Your JBL amp is better than the Sony in not only clean sound but also in the ability to swing volts. Sadly the way the front channel pass though of the GTO 1004 is configured it expects that the front channels will be used to either power a sub (and the pass through amp will power the components) or components (in which case the pass though amp will power the sub).

Using the pass though to power the rear is not an expected use of the amp.

The options you have are....
a. Get a monoblock for the sub. A monoblock not only gives you more power but more essentially offers better control of the sub's heavy cone. Think of this way the subwoofer is a MACK truck, the components are a Ferrari. Now if you drive a MACK truck with a a Ferrari's engine it will work but a MACK trunk's engine (aka monoblock) will be more suitable.

b. Get a HU with 3 pre outs and subwoofer control. I would recommend the Kenwood 994 (993 replacement) as it also has blue tooth built in and as a doctor you might need to use a bluetooth connection from your mobile so you can take and make calls via the stereo. If you do not need this feature the Pioneer 7200/7250 or on a budget the JVC 815/816 are also decent options.

You can ofcourse do both a. and b. :D and be a victim of the thread below.
http://www.team-bhp.com/forum/ask-gu...ing-forum.html

:eek: Navin, he is a PPO (like PIO) from Freedabad, Harryanna!
:Shockked: Highly unlikely!

navin sir i dont know about 993 kenwood but i plan to get 7043bt unit of kenwood with bluetooth and 3 rca outs.

in ludhiana what i have seen are there are fitters not installers. they just fit the parts no cohasiveness is there.

i installed my gto1004 in patiala at authorised jbl dealer .he is a better installer cos he had mentioned that there might be some noise as he had earlier fitted a palio .what he did was that the right channel was going to front components and the left channel to the sub .there was no noise but may be in my enthusiasm didnt note the noise. when i came home i swapped the connection to make it a proper stereo sound. the noise is audible at very low levels like 8-9 on hu as the volume is increased the noise drowns and u cannot appreciate it at all.

any good installers visiting punjab kindly visit ludhiana ur dinner and drinks are on me .if i can get a free consultation lol

RCA, possible, but again if the earthing is good noise in RCA will only be from passing vehicles without good earthing, like autorickshaws, old scooters etc. Power cable is usually not at fault.

In your case, it is quite likely a bad earthing contact. What you could try doing:
* Get a copper washer brazed at the seat-belt bottom bolt location. The inner dia of the copper washer should be slightly larger than the bolt size (otherwise you will not be able to put the seat-belt bolt back). Use acid to clean the body around the bolt hole before brazing the washer
* Get the amp earthing cable to this point, clean the exposed end well, and terminate using a crimp lug
* Put the crimp lug first to the copper washer, then the seat belt plate, then the original steel washer, and then tighten bolt on to this.

Is not Ludhiana a large city? I was given to believe that Punjab is India's richest state and there are more Mercedes in Punjab that any other state in India (incl Delhi).

Wow there actually is a town called Patiala! Things you learn on TBHP.

Rupinder your amp has 4 channels. Front (Right and Left) and Rear (Right and Left). What your installer should have done to start with is to bridge (convert 2 stereo channels into 1 mono channel) the front channels and send them to the sub and use the rear (in stereo mode) for the fronts. If he did not do this find a better installer. Sadly sitting in Bangalore (DA) or Mumbai (me) we cant help much from here that is why I suggested LBM becuase he is a lot closer.

Suffice to say that you ahve 2 seperate problems
1. Install issues. Which is letting in noise
2. Flexibility of controlling the subwoofer levels etc. which you can reslove by getting a HU with subwoofer outputs and controls.

Lets first solve the first part.

Navin Ji I am just 300 kms near to him !!!

As far as cities go, I thought that credit went to Kolhapur.

:eek:

akdich barobar. marathit mhan aahe ki kolhapural mhasi peksha jaast mercedes aahet.

"there is a saying in marathi colloquially put, there are more mercedes cars in kolhapur than the number of buffaloes"... apun to ekdum aisaich bambaiya ka fan hai!!:uncontrol

navin sir what he did was . there was one rca out from my hu. he took y splitter and thus got 2 separate inputs for front and rear. then he fed the components from the front out and bridged the rear out to the sub . as the bass boost option is with rear out
what i didnt like was that he made both front and rear mono cos the front components were the right channel and the sub was fed by the left channel which i changed so that the front channels are stereo but that resulted in the sub also being given a stereo out .how can i make front to have stereo and sub mono .kindly guide me in the connection

There was one RCA out or one PAIR of RCA out? Ideally there needs to be ONE PAIR of RCA out to even attempt stereo sound. To drive the subwoofer in mono all one needs to do is use the bridge connections for the rear channel.

By splitting the HU out and then sending the outputs of both part of the splitter to the same amp there is a huge chance of making a ground loop and all 4 channels in the 1004 probably share a common ground.

For your initial tests ignore the Y splitter. Run the HU directly to the front channels of the amp and connect the front speakers to these 2 channels (no sub, sony amp or rear speakers). Now see if there is noise. If this works we'll introduce the next level of complexity.