[supertinu]

Originally Posted by SolidSnake

Are you sure that the high frequencies started missing , offlate only ? If yes , then its not a high level inputs issue . But if the high frequencies have been missing since the install , then its a problem with the high level inputs for sure .

No this problem happened only recently. Last few weeks. The ICE setup is probably a year old now.

Originally Posted by Sunsh!nes

This could be a issue with the Wiring or the Amp having some issue. Try changing the RCA cables by swapping them to the front and see if there is any difference.
Checking the HU is also recommended as it might also be encountering some issue.

Yes I need to spend more time debugging this. Been occupied at work and home. Only quick check i had done was plugging the rear channel HU output to front channel of the amp and still the hi freq was missing. So Amp cannot be ruled out.

[DerAlte]

Originally Posted by supertinu

... So Amp cannot be ruled out.

That is not the right way to check the amp's culpability. The right way is to swap the front and rear speaker cables - at the amp output. If the amp is at fault, the rear speakers will stop giving out hi-f. If the front speakers are at fault, even the rear feed - which one can assume was playing OK with rear speakers - will not sound right with front speakers.

[supertinu]

Originally Posted by DerAlte

I would think it is a simple issue of dry / open soldering of components in the cross-over.

Originally Posted by navin

Be careful with that. 1.5V is about half a watt in 4 ohms. Some delicate 1/2" dome tweeters can't handle even that much since it is DC.

Well gentlemen we have the root cause. It was the crossover on both sides which was the culprit and the issue was rain water. I had checked the tweeters at home and knew they were fine. Went to the installer and he opened the door pads and checked the crossover. Despite having sealed and wrapped both the crossover myself they were completely wet and in horrible state. The sound would have deteriorated gradually I guess but I didnt notice till treble disappeared. Anyways the installer didnt have crossovers only but he said that he will check with JBL office to see if their are some spares or returns lying around.

I am semiconductor HW Design Manager by profession so on the way back home it got me thinking that unless the components themselves have gone bad inside the XO, it should still be salvageable. Its just a LC filter in the end. So once i was home and thanks to Lok Sabha election holiday I spent rest of the day in operation XO cleanup and voila 90% of my sound quality is back. Their is minor imbalance between the two XO. Need to figure that one out.

Listing below the steps I did followed by pics of the XO in each stage

• Removed the XO, opening up and cleaned up the PCB with spirit

• Baked the entire PCB in a home OTG at 100-120 deg C for 20 mins to dry it out completely

• Scraped all the contacts + re did all the solder joints with a home soldering iron

• Checked all the components with a DMM, looked ok

• Refitment in the car and 3 layers of plastic insulation vs 1 earlier. Plus lots of electrical tap for sealing. Hopefully this will keep water at bay.

XO after removing from car and just dried from outside



State of affairs inside the XO. The PCB and contacts were in horrible state




Baking time, desi style judaad


PCB After the clean up and resoldering


Wire contacts all cleaned up


Since the cross over is big in size the spot it fits into the door is at the bottom. Any ideas from the forum on better placement or water insulation are welcome.

[DerAlte]

Originally Posted by supertinu

... It was the crossover on both sides which was the culprit and the issue was rain water. ... Any ideas from the forum on better placement or water insulation are welcome.

1. Apply white petroleum jelly (Vaseline) on the screw terminals after connecting. This will prevent terminal corrosion

2. Get a couple of Ziplock bags (the resealable type plastic pouches). Keeping the terminal side at the bottom, insert the XO and 1-2" of the wires into the pouch. Close the zip as far as possible, wrap the zip end over itself and tape up this end. Mount the XO pouch, wire side at the bottom, using double-sided tape to the middle metal layer of the door. Water will now drip off the XO instead of entering it.

[greenhorn]

Originally Posted by supertinu

Well gentlemen we have the root cause. It was the crossover on both sides which was the culprit

I would Like to take this opportunity to say I told you so!

Since the cross over is big in size the spot it fits into the door is at the bottom. Any ideas from the forum on better placement or water insulation are welcome.

Move it to under the kick panel, in the footwell.
http://www.mustangspecialties.net/im...93-ecm-loc.jpg

this place

[DerAlte]

Originally Posted by greenhorn

... I told you so! ...

Oh yeah? You said ...

Originally Posted by greenhorn

crossovers/tweeters might have been disconnected during service, hence not working. If your mid basses are working, then the problem is after your crossover

Originally Posted by greenhorn

... Move it to under the kick panel, in the footwell. ...

+1. I have mine mounted above the pedals on the firewall. Safely out of harm's way!

The problem is it doesn't occur to most installers, for some strange reason. Everyone puts the XO in the door cavity. If he wants to change the location now, he will fall short of cable!

[navin]

Originally Posted by supertinu

Since the cross over is big in size the spot it fits into the door is at the bottom. Any ideas from the forum on better placement or water insulation are welcome.

Originally Posted by DerAlte

+1. I have mine mounted above the pedals on the firewall. Safely out of harm's way!

Since I use DSps and Amplifiers which are in the trunk I mount my crossovers in the trunk too (behind the rear seat). Never had a problem, even after driving through 16" of water on 26/11/2005.

[supertinu]

Originally Posted by DerAlte

1. Apply white petroleum jelly (Vaseline) on the screw terminals after connecting. This will prevent terminal corrosion

Originally Posted by greenhorn

I would Like to take this opportunity to say I told you so!

Originally Posted by navin

Since I use DSps and Amplifiers which are in the trunk I mount my crossovers in the trunk too (behind the rear seat). Never had a problem, even after driving through 16" of water on 26/11/2005.

Well gentlemen as they say, life is never simple. Remember I mentioned the problem was reasonably fixed but their was a mis-match between the channels. As it turned out the delta seemed to get worse within a day and eventually treble on one of the channels was completely gone. I was back to opening both the doors and removing the crossovers. Root cause was finally the HPF filter cap which was completely off in its value. I am assuming when I baked the crossover the cap got heated and had a change in its value which helped its performance initially.

Anyways thanks to the silkscreen on the PCB when I removed the old cap, I figured its exact value 4.7uF. After some research online and link below I found that polypropylene dielectric caps are best for audio applications

http://www.chokes.com/crossovers-explained.html

Again thanks to google I found another stockist which delivered the specific 4.7uF 250V cap to my doorstep at the lowest price without charging ridiculous shipping charges despite the part being shipped from UK.
http://in.rsdelivers.com

The parts arrived yesterday. Reworked both the crossovers to avoid any mismatch on filter characteristics on both of them and after some testing fixed everything back in place. Results were great and things are back to as good as new . Along with this I changed all the wiring inside the door as well to get better quality wiring. Finally persistence has payed after almost a month since i started looking at this problem. My apt complex guys also must be wondering whats up with this guy, opening door pads every weekend

Now some pics

Old cap


Reworked PCB. Had to twist the leads since the form factor was slightly different.

[greenhorn]

next time, there are decent options in india itself
http://www.diycomponents.in/ProductD...rrent_SKU=1219

[DerAlte]

Originally Posted by supertinu

... Had to twist the leads since the form factor was slightly different. ...

Wonderful! Great job.

Originally Posted by greenhorn

next time, there are decent options in india itself ...

There is no dearth in Bangalore itself (@supertinu's location says Bangalore) - a couple of streets worth of shops (SP Lane, parallel to SJP Road; full of component shops). If one is not lazy to go there, that is!

[supertinu]

Originally Posted by greenhorn

next time, there are decent options in india itself
http://www.diycomponents.in/ProductD...rrent_SKU=1219

Thanks greenhorn, I didnt know about this particular website. Though seems like they dont stock the part that I finally ordered but I could have lived with a 100V cap as well.

Originally Posted by DerAlte

Wonderful! Great job.

There is no dearth in Bangalore itself (@supertinu's location says Bangalore) - a couple of streets worth of shops (SP Lane, parallel to SJP Road; full of component shops). If one is not lazy to go there, that is!

DeAlte you are right about my laziness to go to S P Road . I live in Marathahalli area and driving across town for 2 capacitors some how just didnt justify the effort on a precious weekend. So online ordering and doorstep delivery worked well. I do visit SP rd once a yr when I have enough items lined up to buy.