[ibo]

Hey all, I could def. use some help here. Searched but nothing helps so far. I recently upgraded to VP's HIFI upgrade. Upon concluding the install, I noticed a subtle but noticeable hiss (white noise?) coming from the tweeters. The level of hiss does not increase with volume.

Here are the steps I took to troubleshoot the issue.

1. Change ground location from rear fender well to battery/chassis ground behind the rear bumper plastic trim.

- No change.

2. Adjust gain on amp (first tried ARC mini and then tried JL XD600/6).

- Hiss increases and decreases with gain adjustment but even at minimum gain, the hiss is still noticeable.

3. Unplug RCA plugs.

- Hiss is gone.

4. Plug in ipod with RCA adapter.

- Hiss is not present, bliss.

5. Changed the ARC mini back to stock HIFI amp.

- Hiss is gone. I have to point out that even before the upgrade, I could hear a very VERY quiet hiss through stock amp/tweeter if I put my ear one inch from the tweeter. I've always just thought that this was normal. With new speakers and stock amp, the same QUIET QUIET hiss is there, which is significantly more quiet than the new ARC mini.


At this point, I've troubleshooted with VP plenty of times via phone and he graciously sent me a JL XD600/6 with new harness to test with.

6. Replaced amp with new JL XD600/6.

- Same hiss as with the ARC mini amp.

At this point I'm kind of stumped. I can use any help or suggestions that yall may supply. I'm starting to wonder if my head unit is crazy noisy and I've read somewhere online about audio vs chassis ground which confused me quite a bit. Any pointers will be appreciated. Thanks guys!

[kmarei]

Did you try another RCA cable?
Ideally a good quality one

[ibo]

Originally Posted by kmarei

Did you try another RCA cable?
Ideally a good quality one

Well, I've tried 2 different Technic harnesses from VP. Unfortunately both harnesses have the exact same issue. If so many people are using Technic's harness with no issues, I'm fairly sure that shouldn't be the culprit, especially not on two different harnesses.

[kmarei]

Originally Posted by ibo

Well, I've tried 2 different Technic harnesses from VP. Unfortunately both harnesses have the exact same issue. If so many people are using Technic's harness with no issues, I'm fairly sure that shouldn't be the culprit, especially not on two different harnesses.

But technics harness has female RCAs
I mean the male RCA cable that fits into those, that goes to the amp(s)

[ibo]

Originally Posted by kmarei

But technics harness has female RCAs
I mean the male RCA cable that fits into those, that goes to the amp(s)

Thanks for clarifying this! I read in several places about the female RCA's, but the ones I received from VP are both male. I figured perhaps the newer harnesses have male ends, but now that you point this out, I suppose Ken may have cut the female heads and soldered the males on himself.

However, the current harnesses in my possession have a total length of RCA cable from the harness attachment point to the end of the RCA plugs that is only about 6-7 inches or so. I'm not sure how such a short run of cable can induce so much hiss.

[VP Electricity]

Sigh. Technic changed the harness in the last production run to male RCA. I thought they were getting a little longer but no such luck.

The stock amp is relatively flat from around 3K to 20K, so it *ought* to play any hiss present without attenuation:



But you also pulled the foam out from in front of the tweeters, yes? The stock tweeters would have louder hiss now as well, wouldn't they?

Did you say on the phone that one side was louder than the other? If you swap the RCA, does it move?

I'm worried that it's the HU too. Have not run into this before...

[ibo]

Originally Posted by VP Electricity

But you also pulled the foam out from in front of the tweeters, yes? The stock tweeters would have louder hiss now as well, wouldn't they?

I didn't pull out any foam in front of the tweeters. Was I suppose to? I just removed the backing foam, removed the stock tweeter, installed the new tweeter, and then replaced the backing foam.

Originally Posted by VP Electricity

Did you say on the phone that one side was louder than the other? If you swap the RCA, does it move?

Nope, I didn't say that one side was louder than the other. I just mentioned that without rear speakers for fill, I find myself panning the audio a little to the right side to balance the perception of left and right volume when sitting in the driver's seat (left side speakers are closer to the driver, thus seem louder). If I moved my head to in between the driver and the passenger seat, I wouldn't have to pan the audio.

Originally Posted by VP Electricity

I'm worried that it's the HU too. Have not run into this before...

I really hope it isn't, but if it is indeed the front head unit wouldn't the new tweeters hiss with the OEM amp as well?

[VP Electricity]

Taking the foam sheet out can help with detail.

Just installed this exact system twice this week, but with Morel Dotechs instead of Virtus (from the last batch they had). No hiss.

The iPod into the amp(s) sounds fine, so it's not the Virtus tweeter or crossover set up wrong.

Any difference from different sources?

[ibo]

Originally Posted by VP Electricity

Taking the foam sheet out can help with detail.

Just installed this exact system twice this week, but with Morel Dotechs instead of Virtus (from the last batch they had). No hiss.

The iPod into the amp(s) sounds fine, so it's not the Virtus tweeter or crossover set up wrong.

Any difference from different sources?

No difference. I specifically tested all the sources possible (CIC hard drive, radio, ipod, DVD) with the volume all the way down to 0 or just muted. The same hiss is present.

[udm328i]

sorry about your hiss, and sorry about this
but how do I tighten this speaker directly next to side view mirror, it seems a little loose

[dmatre]

I've noticed that my system also has a VERY SLIGHT amount of tweeter hiss when the car is powered on.

BUT ... with the car running, there's enough ambient noise that the hiss is undetectable, so I don't feel that it's a problem at all (for me). I can't hear the hiss if idling in the garage, so you can bet that on the road it's a non-issue as well.

On my system, the hiss is definitely proportional to the gain, but I've got the gains rather low, so that resolves that issue. (The system will still get uncomfortably loud with the gains set low)

Is your hiss bad enough to hear it if the car's running? Or are you checking it with the car powered up but not running?

[Technic]

Originally Posted by ibo

Thanks for clarifying this! I read in several places about the female RCA's, but the ones I received from VP are both male. I figured perhaps the newer harnesses have male ends, but now that you point this out, I suppose Ken may have cut the female heads and soldered the males on himself.

However, the current harnesses in my possession have a total length of RCA cable from the harness attachment point to the end of the RCA plugs that is only about 6-7 inches or so. I'm not sure how such a short run of cable can induce so much hiss.

The last version of the HiFi harness has male ends as it is now dedicated to XD600/6 installs in the OEM amp location due to most customer requests.



If according to you there was a "QUIET, QUIET" hiss when the OEM amp was plugged in then you will have an increase of such hiss when a more powerful aftermarket amp is plugged in if the chassis ground is used. That is what you are having now, apparently.

My suggestion is to remove the OEM HU, unplug the Quadralock in the back, and take a close look at pin 12 (ground). Make sure that the radio pins and the Quadralock pins are having a solid contact without any wiggling.

[JohanW]

Originally Posted by dmatre

I've noticed that my system also has a VERY SLIGHT amount of tweeter hiss when the car is powered on.

BUT ... with the car running, there's enough ambient noise that the hiss is undetectable, so I don't feel that it's a problem at all (for me). I can't hear the hiss if idling in the garage, so you can bet that on the road it's a non-issue as well.

On my system, the hiss is definitely proportional to the gain, but I've got the gains rather low, so that resolves that issue. (The system will still get uncomfortably loud with the gains set low)

Is your hiss bad enough to hear it if the car's running? Or are you checking it with the car powered up but not running?

I have the same problem as you. Not noticeable when the engine is running and proportional to the amp gain. Increasing the volume of the head unit doesn't increase to volume of the noise except when the HU volume is very near its max.

If the volume of the HU is zero there will be no noise at all but it's enough to increase the volume one click for the noise to appear.

No noise if a smart phone is connected directly to the amp.

I have the relay from technics harness very close to my rca-cables. Could the relay cause any interference?

[ibo]

Originally Posted by dmatre

Is your hiss bad enough to hear it if the car's running? Or are you checking it with the car powered up but not running?

I'm doing the latter, which makes any sort of hiss much more apparent. Like you said, when the car is running, with engine and road noise, the hissing pretty much gets drowned out. But with the ignition off, it's a slap in the face

Originally Posted by Technic

If according to you there was a "QUIET, QUIET" hiss when the OEM amp was plugged in then you will have an increase of such hiss when a more powerful aftermarket amp is plugged in if the chassis ground is used. That is what you are having now, apparently.

My suggestion is to remove the OEM HU, unplug the Quadralock in the back, and take a close look at pin 12 (ground). Make sure that the radio pins and the Quadralock pins are having a solid contact without any wiggling.

Thanks for chiming in. I was worried I'd have to remove the HU. Sigh...I guess I'll have to tackle that when I have the time, just to be completely sure. How hard is this to do?

[ibo]

Does anyone know where the HIFI head unit is grounded? I know of two audio ground points, one on the rear of the driver rear fender well and one on the front of the same fender well.

[taibanl]

Originally Posted by ibo

Does anyone know where the HIFI head unit is grounded? I know of two audio ground points, one on the rear of the driver rear fender well and one on the front of the same fender well.

I have a base HU that is grounded back at the fenderwell so I suspect HiFi is also grounded there. Do you have a brown cable that says audio running from the front of the car to the fwd part of the fenderwell ground point?

[JohanW]

If the noise are present over the complete frequency band it doesn't sound like a ground loop problem (correct me if I'm wrong).
If you have a grounding problem it's very common that the pitch change with the engine rpm.

There are several threads about the same issue but I haven't read one with a solution.

I don't know if spectrum analyzer for a smart phone could be used to find out the fourier transform of the noise.
I think I will try that to know if it's white noise.

[ibo]

Originally Posted by JohanW

I have the relay from technics harness very close to my rca-cables. Could the relay cause any interference?

Just FYI, I tested both harnesses in my possession, one with the relay and one without. While the relay itself produces a single "click" sound when the remote signal is sent from the head unit (expected, as it is a relay), I did not hear any interference caused by it's inclusion nor proximity from the RCA's.

[balu4k]

Hi, Any solutions to this hissing problem. I have the same exact problem after the JL xd600/6 install, i hear the noticeably hiss from my mids even when the HU is off ( ignition on ) or even when HU is playing CD at volume zero. I don't hear the Hiss if i disconnect the RCA's. Mine is HIFI system on E92 2009 model. I even hear the hiss even after lowering the input gain, but the hiss sound is little less but still noticeable.

[ctuna]

No hiss on my JL its grounded on the battery.
04 wire all the way to the battery lugs . Theoretically
it shouldn't make a difference as long as you have a low resistance
ground but my kit came that way(equal length power and ground) and it works. I didn't here anything when I was running the stock speakers alone
on it either. Gains are not set high on the Morels and are zero on the rear stock speakers.