Noise only when Engine is running (Buzzing sound - increase with gain boost)
 

Thank you so much for sorting out my problems in the other thread. I have this current setting now.


I have a 2 way component system setup (2 tweeters and 2 woofers), a Joying HU, a 600Watt Amp + a 400Watt standalone Sub. I run the power wire on the right and audio cables in the middle.

I ran a 4 gauge power cable to the amp, another 10 gauge cable tapped into that for the 400watt sub. 10 gauge ground cable into the ground slot on the Amp + 4 gauge ground cable from that same slot into the ground of the car (bolt of the car passenger seat). I sanded and cleaned the bolt slot before I bolted it down.

https://images-na.ssl-images-amazon....AC_SL1500_.jpg

However, there is this buzzing sound only when the engine is running. It increases when I increased the boost/gain on the amp. It does not change with the RPM of the engine.

I tried grounding the ground cables (both left + right audio output from the HU) onto the HU chassis (there is no RCA cables in the setup). But when I do this, there is no buzz but there is also no sounds. I then tried grouding the Ground cable of the HU itself onto the chassis but there is no changes (buzzing and sound still there).



I tried different ground spots as well but no change. I have no other solutions. Prior to installing the 400watt standalone sub today, the buzzing was very minimal. But it has doubled since the addition of the sub.



This is what I am using.



Rockville SS8P 400 Watt Slim Under-Seat Powered Car/Truck Subwoofer Sub+Amp Kit
https://images-na.ssl-images-amazon....AC_SL1500_.jpg


Planet Audio AC600.2 2 Channel Car Amplifier - 600 Watts, Full Range, Class A/B, 2-4 Ohm Stable, Mosfet Power Supply,

Bridgeable

https://images-na.ssl-images-amazon....AC_SL1500_.jpg

The HIGH LEVEL INPUT. I did not ground the middle wire. When I tried to ground to the chassis (same ground point as the 4 gauge wire), the buzz gets very bad. Should I ground this wire back to the HU or HU chassis?

Thank you for your time.

Possibly alternator/regulator noise. If so, the noise is coming in on the power, not the ground or the audio inputs. You can buy/make a noise filter that goes on the input power to the equipment.

Might be a faulty audio cable(s) that is not adequately shielded.

Edit: Another possibility is that the speaker wires are acting as antennae. Keep them (and all other wiring) as short as possible.

Have you considered trying the use of the low level outputs from the Joying head unit
coax (sub) and phono (R & L) for connection to the subwoofer amp and two channel amp?

I am an audiophile (5.1), not a car audiophile but I believe this would be my preferred connection method.

A few things:

1) If the buzzing/noise (interference) was there before, adding another amp just amplified it (no pun intended).

2) You can't ground the audio outputs, each speaker has a +/- that needs to be connected to complete the series. You removed it, didn't complete the series, and thus lost sound (not sure how that would work if you grounded both the input on the speaker side and the output on the headunit/amp side, but never been tempted to find out). That being said: I'd replace them with good quality RCAs from the headunit to the amps.

3) Check your grounds and their distance. I've always been taught that grounds should be as short as possible. Where are your amps located? If they're somewhere in the trunk, and you're running your ground to a seat, that's a pretty long distance. Also, I'd ground each amp to a different point.

4) If you're going to run your amps off of the same cable, use a power distribution block to separate them. For example: I only have a single amp, but my compressor and crossover require power as well; so I have a 0 gauge (fused, forgot the size) from the battery to the distro block, then a 4 gauge (fused) to the amp; and two 8/10 gauge cables (each, fused) to the compressor and the crossover. Each has a different ground. The only thing that is shared is the remote/signal wire from the headunit to the amp which then feeds the crossover.

My advice would be to trace the initial source of interference. I'm sure BigAudioFanat or RonRizz will chime in later as both of them are leagues ahead of me knowledge-wise.

They both have a lot of experience with modern systems and have been very helpful to others. Although the basics haven't changed over the years, some of the details have (we never had to worry about such things as LOCs back in the Good Old Days).

I placed the armp (it's quite small) right under the passenger seat. So the ground cable is about 1ft in length. I used a 4 gauge cable for power and ground even though 8 gauge is adequate for the amount of RMS (100watt RMS constant, 300 RMS max). The sub itself has only 100 watt RMS. So the 4 gauge should be adequate for a total of 200watt RMS max.

I have never used the RCA inputs. I will try that today as I have 2 pairs of RCAs.

I am also considering ground loop. There is a ground bolt on the chassis under the kick plate of the passenger side. Maybe move the ground point to here? This however will lengthen the ground cable to about 3-4ft.

I have no idea where the source of interference is. When I remove the high level input from the HU to the amp, there is no sound and thus no buzzing. Therefore, it's probably somewhere from the HU to the high input of the amp?

What's the different between Low Level (RCA) vs High Level (audio +/- cable)?

I have turned the gain all the way down but it's still there. As is now, I can't use any gain at all.

Thank you for your time.

Edit: Just ordered 3 RCA to 3RCA. The Sub(Coax) will be with a Y-splitter to the Sub as it accepts 2 channels. Also ordered a ground noise isolator just in case for the RCA.

First off you're using too small of a power wire (10 gauge) to power your sub amp needs to be at least 8 gauge.

Second, your grounding location did you grind off the paint and expose bare metal? Have you tried a different grounding location?

The sound you're hearing is alternator wine. With those brand of amps their noise floor is very high so they re much more sensitive to dirty power. Yes I'm calling them cheap.

Where did you ground your head unit at? Any bare metal behind the head unit is okay just do not use the black wire in the factory adapter harness it doesn't go anywhere. This can cause noise.

Does the noise disappear when you unplug the RCA's from the head unit? If this is the case the noise is coming from the head unit and you need to work on it's ground. If it doesn't go away try unplugging the rca's from the amps. If the noise goes away move the rca's to the other side of the car. If you're using high input go to rca's

The difference between high level input and rca's you're letting the amp do the amplification where as high level the signal is already amped from the head unit and the amp has to filter it down to low level in order to use it.

Regarding amp's location, I sanded down the bolt and the seat metal. I will try grounding it behind the kick plate today.

I don't have RCA yet but when I removed the high level input, there is no sound and the buzz disappears.

As for the HU, there is no specific ground cable. I used the harness. I also tried connecting the GND cable from the harness to the HU chassis but this has no effect. This is all using high level input.

I am aware of the need of grounding the HU if case using the RCA's. Yes, the amp is quite cheap. it was only $60.

- Regarding ground of the HU. Do I cut the GND wire and try to ground to the chassis? Or I tap a wire from the HU chassis connect to the car chassis?

That black cable in the head units harness should ONLY be going to a metal chassis somewhere behind the head unit not to the rca's.

Swap to RCA's

Why use RCA (consumer line level) vs high-level?
RCA cables are shielded whereas high-level is seldom shielded.
Amps usually use a resistor network to drop the high-level signal to the 1 VP-P that consumer line level uses. Give the amp what it wants.

So just to clarify, I cut the GND cable from the harness and ground it to the metal chassis? instead of it going into the factory harness?

I ordered some dual shielded RCA. In the mean time, I will try the cheap RCA's I have lying around.

Yep, nissan's don't have a factory ground the adapter harness you bought with the black wire is only for Subaru

https://pisces.bbystatic.com/image2/...0;maxWidth=550

I am using the included joying harness. It has a GND cable here. Are you saying when this harness connect to the factory harness. It goes no where? if so why the HU still works?

https://www.joyingauto.com/pub/media...n_blog/3-7.jpg

But thank you for answering all my questions.

Most radios have multiple ground paths - the wiring connector, the radio chassis where it bolts to dash, antenna connection, etc.

Switched out to RCA ($9). The buzzing from the HU and the Amp is completely gone. I can finally use the gain boost from the amp. Cut the 2 grounds cable of the HU to the harness. The thick black wire doesn't go anywhere. I grounded them both to the frame.

There is a very small buzz (even when either RCA's end are unplugged), it's very faint, can't hear when the music is even at volume 1, you can only hear if you kind of try to listen for it. I have no idea where this comes from. Only when engine is on.

Thank you everyone for your help!!!