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That's interesting. Looks like in this case the DSP was picking up noise wirelessly from the battery, as it was located almost right next to it. I can definitely cover the battery with a piece of soundproofing foil. But I have previously moved the amp to the backseat, far away from the battery.

With the amp powered from the battery and the car off, there's no noise unless, for example, I connect that usb dongle to an exterior power source. Like when I plug the adapter into household outlet.
But if I power the dongle from USB port on the headunit, there's no noise (that's with the car off). But when I start the car, even if dongle is powered from HU usb port, I can hear a small whine, suggesting some interference is getting into the amplifier.
That's why I'm not sure if the battery can be causing it.
I'll double check again, but when I use my phone via rca adapter to send input into the amplifier, I don't have any noise or whine.

So maybe I'll just have to settle for using my phone via 3.5mm jack to play music.

But if the battery is causing any interference, what I'd really like to know if how to test for it. I haven't heard of having interference from battery if a filter is installed, like I did in my case.
You know what I feel for you and your situation sux. 300 post and a grip of effort you have put out and no solution. I wish I could help. I say you find the quietest of all of the solutions and live with it. I would have quit a long time ago and just used headphones.
 

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c'mon man..... ^^ this is not a thing. you go find that article... let us know.
please don't post unless you have real information.

batteries themselves are quite sources of DC voltage. 🔋
Without a doubt, batteries are a great source of DC voltage. But we're not talking about voltage here... Did you even look at the post I linked to?
 

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2018 Honda Accord EXL 2.0 GB 3way doors GB40/10 centre Helix M4dsp/M6 Sundown salt MMats + more
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whoa mind blown, good link. love Motorola, btw.
so all the different currents being drawn from a battery at different rates/speeds generate noise, depending on the battery cell geometry.
this article appears to be related to cell phones and cell phone pouch LiIon batteries.

you think this applies to automotive (SLA) batteries though?
I guess it probably does ... since vanguard posted about it.
f me in the b hole. thanks for posting. i'm shocked batteries can generate EMI!

 

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Discussion Starter · #308 ·
Thanks for your contribution man! My case is definitely not simple, so something crazy like this could be the issue.

So I came back to the car, it fully charged, and now I don't hear the static in the tweeter if I have my battery tender plugged into house outlet.
I'm thinking maybe the battery is full and is not drawing power and hence it's not adding extra noise into the system.

Then I tried plugging the BT dongle power adapter into home outlet, and could here buzzing in the speaker.

Then I used a cigarette lighter in the trunk and powered the BT dongle with USB cord from cigarette lighter adapter, and there was no static or buzzing.

When I started the car, unfortunately I heard the faint whine again.

I removed speaker wires from the amplifier and tested for continuity between each speaker and battery positive and negative. All readings were infinite, do definitely there's no shorts where.

I guess I'll take it for a drive and see. Last time I thought I got rid of the whine, took the car for a drive and heard the whine.

Actually now when I first started the car, I was listening and heard no whine. But after a few seconds, I could hear the whine.

I don't know if it's something that builds up after a few seconds or what's going on.
 

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if you think the noise is being emitted by the battery, you can try a metal battery case, you would want enclose it in metal.
the resonix stuff has a layer of lead in it.

you can try aluminum foil as a test. wrap the the battery with aluminum foul, couple layers.
you can also wrap your DSP in it to shield that see if any of that helps.

if you're doing any of that though, make sure you do not short anything out.
 

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Discussion Starter · #311 ·
The way the battery sits, I don't really have a way to encose it in metal. But if you look at the picture, I can definitely throw some foil overtop and it will completely cover the battery. I don't have DSP but I can also put foil all around my amp.
I don’t have any foil sheets but this product has a layer of foam so I figure that should work?
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Right now I'm testing with BT dongle vs phone.

So I use 4 rca splitter to 3.5mm jack.
4 rca cables go to 4 amp channels, and 3.5mm jack goes either into my phone or into the USB dongle.
 

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Discussion Starter · #312 ·
I was ready to give it a go.
Added a layer of the sound insulation I linked above.
I decided to change where I was attaching positive cable for the amp. No clue if it does anytning or not, but I was attaching positive higher up on the battery clamp, where the wires from the alternator return to power the battery, and also where it has a inline battery cable fuse that disconnects the battery in case of collision. No clue if this could've caused any problems or not, as it's all on the same clamp, but I changed it as per the arrow on the screenshot.





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Then I readjusted amp gains to my phone as a source and took my gf for a ride lol. We both listened and I set the music to be as loud as possible.
Even with music on pause, there no noise, no whine, no static and no buzzing. There's a tiny bit of white noise, which is more than acceptable to be and barely audible with my ear stuck on the speaker/tweeter.

The other thing I did was to move my second amp filter.
Instead of it being as I pictured previously, between the battery and the positive cable for the amp, I moved it up the chain and installed it in between the splitter fuse (where 0 gauge wire splits to power 2 amps) and the amplifier.
So it's kinda weird in a way. I way 0 gauge wire running to the fuse where it splits, and then I have this 50amp filter going between the wire splitter and the amp.
It's funny because it's like 10 gauge wire.

My amp's manual said to install a 40 amp fuse before the amp, which I did. And the 50 amp filter seems ok then.
But then the manual for the amp says that it should be powered with a minimum of 4 gauge ofc wire. So I don't know if I did any good replacing 0 gauge wire for the speaker amp with this filter lol. It only has 10 gauge wire I believe. I don't understand these filters. Their wires are tiny. You get told to use 4 gauge or 0 gauge wires for your connections, and then they suggest you put these filters with tiny wires. Maybe it doesn't matter because it's so short?

Now last thing I want to do before declaring victory is to connect the second amp and sub.

How can I feed signal to the 2nd amp?
I have two rcs pre outs on my first amp, so I was wondering if I should use them?
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Or I can add another splitter to this splitter and have 6 rcas split from one 3.5mm jack. Is that ok? Does it matter to split the blue/red rca plugs equally or not?

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You could use your outputs of your amp or the splitters. Either will work. Or you can get a DSP that only needs 1 input to control your whole system lol 😵‍💫
 

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Discussion Starter · #314 ·
The only reason I'm not going with dsp is because I already have crossover for my speakers and tweeters in my doors. So dsp wouldn't do anything for me I think.
Unless I take apart the doors again and rewire everything.
I want to be done with this project, as you have witnessed almost first hand, it's been pretty exhausting :)
All I want is to have no interference and enjoy the car and the music. And right now I'm 100% happy with the sound, just the bass is missing.

After all I've learned, I can do full throttle on my other car, E39.
I plan on doing a ton of retrofits and upgrades on it so the car will be fully stripped and soundproofed as well.
In that case I can do helix bluetooth dsp+amp and any other components.
 

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The only reason I'm not going with dsp is because I already have crossover for my speakers and tweeters in my doors. So dsp wouldn't do anything for me I think.
Unless I take apart the doors again and rewire everything.
I want to be done with this project, as you have witnessed almost first hand, it's been pretty exhausting :)
All I want is to have no interference and enjoy the car and the music. And right now I'm 100% happy with the sound, just the bass is missing.

After all I've learned, I can do full throttle on my other car, E39.
I plan on doing a ton of retrofits and upgrades on it so the car will be fully stripped and soundproofed as well.
In that case I can do helix bluetooth dsp+amp and any other components.
You'll be fine using the output of your amp then. It's just an internal Splitter actually meant for an other amp.
 

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Installed OFC for ground and power wires going to the amp, I think the whine is gone.
Also, I used 0 gauge wires from battery and ground to the amp. I used 4 gauge to 0 gauge reducer connector to use 0 gauge wire.

Installed an extra fusebox and fused both amps at 40 amps as per manual from RD400 JL.
The new amp I bought for my speakers, RD400 JL, has a clip light to set the gains.

So after setting everything up, I don't hear the whine anymore. I think those magnets were making things worse. Power wire was probably creating a small magnetic field, and these magnets were making it worse. Who knows!
Now I do get a slight static from the speakers/tweeters when the music is paused. My gains are dialed in properly.

The static at some point got extremely bad as I was testing, and I saw that one rca cable fell out of the headunit. I put it back, and as I was wiggling the rca cables in the headunit, the static would change.
Now I'm thinking it's the rca cables causing static due to not being well grounded inside or smth. I bent the rca connectors to make them tighter, so they're super tight on the headunit plugs, but the static is still there.
I dont know how to exactly describe it, it's like a static mixed with some hissing/sheeshing and is rhythmic. It sounds like a small bird flapping its wings.
I'm thinking Monoprice rcas are not high quality cables and I heard people complain in reviews about loose connections.

I ordered Amazon basics rca cables again.
I also ordered BJC LC-1 Stereo Audio Cables.
There's so much mumbo jumbo on the internet with regards to interconnects, but I think BJC are considered no shill high quality cables. They set me back $250 but I hope a pair or BJC and Amazon rcas will allow me to figure out if the static is caused by rca cables or something else.
I have used Stinger 4000 series rca's and found them to be quite good, but, I also had to squeeze the outer ring to tighten it up a bit and open the split center pin just a hair. This might be something to try with your cables, if they have a split center pin. Both of those contacts are equally important. Very carefully use a knife to open up the center pin just a tiny bit until it fits snugly.
 

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Discussion Starter · #317 ·
Thanks! The only short cables I have are 1 male to 2 male rca. To run from one amp to the other. Can I plug the one male end into my speaker amp and connect the 2 male plugs on the other end to the sub amp, or does it have to be one for one, same colors?

I was wondering what's the point of actually having 6 channel output headunits, if you can split a single output into 6 outputs without loss of quality?
 
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