[supertinu]

Dear Experts. I am facing an issue with the ICE setup in my car offlate and need your advices on possible root causes.

First the setup. I have a Ford Figo with stock HU retained.
AMP - Ground Zero 4-Ch Amp Model no - GZIA 4115HPX with in built Hi-Low converter for the stock HU
Front Speakers - Infinity Reference Series Components 6830CS, 8x6 inch ovals as per door size
Rear Speakers - Stock OEM
Sub - Ground Zero 10 inch, sealed enclosure

Front components run on 2 CH of the amp fed by the HU. Sub runs on the other 2 CH of the Sub fed by the rear channel of the HU. The rear door speakers are again directly fed from rear channel of the HU.

Offlately I started to feel that the sound stage has moved to the rear. Upon close inspection realized that there was no high freq reproduction coming from the tweeters in the front. This is common to both the front tweeters. I am getting more treble from rear stock speakers. To get more idea i swapped the Hi inputs going into the amp. Again same result, no high freq. By this way, i am concluding that

- HU is probably ok, since the rear channel treble is fine
- Amp cannot be ruled out since the rear channel input is fine on the hi side and still no HF output on CH1/2
- Something wrong with the components, crossover or tweeter. But i find it low probability since how can it happen together on both sides, I never listen at high volumes.

Experts, please give me ideas as to how i can debug this more and identify the source of the problem. Last option ofcourse is to take it to the installer when i can find the time. Attaching a pic below of the Amp's input side setup. Ch1/2 are front components and Ch3/4 are for sub.

[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

[Epic]

Hi Supertinu,

There can be various reasons for this:

- Issue with the crossovers
- Issue with the tweeters themselves
- Issue with the RCA cable. However, this would affect the mids too
- Issue with the amp's front channel. But again this would affect the mids too.

I remember facing an issue with my right tweeter in my car where the sound had diminished. It had not totally gone off but reduced drastically. On interchanging the left tweeter with the right, it sounded fine which ruled out a connection, amp or cross over issue. The issue was obviously with the tweeter. On having it sent for repairs, it was concluded that apparently some sort of glue used in the tweeter had melted due to heat as my tweeter are placed on the dashboard. The glue was restored and tweeter was back to original.

However, the puzzling thing here in your case is that both tweeters seem to have lost their sound together which is certain to be a (loose) connection issue.

I would recommend interchanging the front speaker connections with the rear and see if the rear are performing like they should. This would narrow down the the reasons for the issue.

[navin]

Originally Posted by supertinu

Experts, please give me ideas as to how i can debug this more and identify the source of the problem.

Originally Posted by Epic

- Issue with the crossovers
- Issue with the tweeters themselves.

Tweeters can die due to various reasons. More common is over excursion than over heating itself.

The simplest method would be to measure the impedance of the tweeters and see if they are in the 3-4 ohms range. If they are not they might show "open" aka infinite impedance which means the tweeters coils might be blown.

This can happen if by accident some short term peak (maybe the system was left on when the car was turned off and when the car was turned back on there was a lot of energy sent to the tweeters) damaged the tweeters.

[DerAlte]

I would think it is a simple issue of dry / open soldering of components in the cross-over. This is usually the most likely cause. The other cause could be blown tweeters - sincerely hope not.

Open the XOs, and check with a magnifying glass. Shake the components and check which is loose.

[supertinu]

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

I doubt that since the mid range speakers are working fine. Its only the tweeters and the crossver is inside the door hence not accessible.

Originally Posted by navin

Tweeters can die due to various reasons. More common is over excursion than over heating itself.

The simplest method would be to measure the impedance of the tweeters and see if they are in the 3-4 ohms range. If they are not they might show "open" aka infinite impedance which means the tweeters coils might be blown.

This can happen if by accident some short term peak (maybe the system was left on when the car was turned off and when the car was turned back on there was a lot of energy sent to the tweeters) damaged the tweeters.

Good point about the impedance. I have a DMM handy to check that. Thats the easiest thing to start with.

Originally Posted by DerAlte

I would think it is a simple issue of dry / open soldering of components in the cross-over. This is usually the most likely cause. The other cause could be blown tweeters - sincerely hope not.

Open the XOs, and check with a magnifying glass. Shake the components and check which is loose.

My suspicion is gradually moving towards blown tweeters though I cant figure how. If it was a soldering issue, then both the crossovers wont fail together. Back of my mind suspect is that my car cleaning boys might have listened to some loud music during inside cleaning and blown it. Will update once i check the impedance.

[greenhorn]

Originally Posted by supertinu

I doubt that since the mid range speakers are working fine. Its only the tweeters and the crossver is inside the door hence not accessible.

For any sort of work that involves removing the dashboard/A pillars/plastic panels under the dashboard, there is a strong chance the wires going from the Door to the A pillar might get cut/disconnected.

Also, stupid question, Is the Ch1/2 XO set to LPF by any chance? doesnt look so from the pic, but still to be sure

[supertinu]

Originally Posted by greenhorn

For any sort of work that involves removing the dashboard/A pillars/plastic panels under the dashboard, there is a strong chance the wires going from the Door to the A pillar might get cut/disconnected.

Also, stupid question, Is the Ch1/2 XO set to LPF by any chance? doesnt look so from the pic, but still to be sure

Yea, there was no work done in the interiors that can lead to wires getting pulled. Its a relatively new car ~2yrs.

The Ch1/2 are set to HPF. I even moved the crossover switch to see if there was a contact issue but didnt seem like.

[SolidSnake]

Seems to be an issue with high level inputs. Check with a good installer in your city

[DerAlte]

Originally Posted by supertinu

... My suspicion is gradually moving towards blown tweeters though I cant figure how. ...

If you don't have a DMM, there is a simple check to see if the tweeters are blown.

Take a penlight battery (1.5V) and connect to the (disconnected) tweeter wires. If the tweeter is not blown, it will make a tik-tik sound on connection / disconnection.

[navin]

Originally Posted by supertinu

.My suspicion is gradually moving towards blown tweeters though I cant figure how...

Originally Posted by DerAlte

Take a penlight battery (1.5V) and connect to the (disconnected) tweeter wires. If the tweeter is not blown, it will make a tik-tik sound on connection / disconnection.

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. Usually car tweeters sold in moderately priced car stereos are like this 1/2" dome with a 4.7/3.3uf cap in series basically making a 1st order at say 8-10k! yes just open and see!

[supertinu]

Originally Posted by DerAlte

If you don't have a DMM, there is a simple check to see if the tweeters are blown.

Take a penlight battery (1.5V) and connect to the (disconnected) tweeter wires. If the tweeter is not blown, it will make a tik-tik sound on connection / disconnection.

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. Usually car tweeters sold in moderately priced car stereos are like this 1/2" dome with a 4.7/3.3uf cap in series basically making a 1st order at say 8-10k! yes just open and see!

Thanks for the inputs DerAlte and Navin. I am going to check the tweeters coming weekend. Couldnt do it this passed weekend as my 6 wk old daughter has been keeping me occupied . She goes to her maternal grand parents place this week, will give me some free time on the weekend to tinker around. Will keep the forum updated on the findings.

[supertinu]

Originally Posted by SolidSnake

Seems to be an issue with high level inputs. Check with a good installer in your city

Missed your post earlier. How do you think this is a high level input issue?

[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 .

[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.